WO1995015841A1 - Machine for making objects by selectively photopolymerising layered liquids or powders - Google Patents

Machine for making objects by selectively photopolymerising layered liquids or powders Download PDF

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Publication number
WO1995015841A1
WO1995015841A1 PCT/FR1993/001218 FR9301218W WO9515841A1 WO 1995015841 A1 WO1995015841 A1 WO 1995015841A1 FR 9301218 W FR9301218 W FR 9301218W WO 9515841 A1 WO9515841 A1 WO 9515841A1
Authority
WO
WIPO (PCT)
Prior art keywords
mask
active
machine according
liquid
stereolithography machine
Prior art date
Application number
PCT/FR1993/001218
Other languages
French (fr)
Inventor
Lucas Goreta
Original Assignee
Finab Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to FR9207158A priority Critical patent/FR2692053A1/en
Priority claimed from FR9207158A external-priority patent/FR2692053A1/en
Application filed by Finab Limited filed Critical Finab Limited
Priority to PCT/FR1993/001218 priority patent/WO1995015841A1/en
Publication of WO1995015841A1 publication Critical patent/WO1995015841A1/en

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Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70216—Mask projection systems
    • G03F7/70283—Mask effects on the imaging process
    • G03F7/70291—Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
    • B29C64/10—Processes of additive manufacturing
    • B29C64/106—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material
    • B29C64/124—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material using layers of liquid which are selectively solidified
    • B29C64/129—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material using layers of liquid which are selectively solidified characterised by the energy source therefor, e.g. by global irradiation combined with a mask
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/0037—Production of three-dimensional images
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/20—Exposure; Apparatus therefor
    • G03F7/2002—Exposure; Apparatus therefor with visible light or UV light, through an original having an opaque pattern on a transparent support, e.g. film printing, projection printing; by reflection of visible or UV light from an original such as a printed image
    • G03F7/2012—Exposure; Apparatus therefor with visible light or UV light, through an original having an opaque pattern on a transparent support, e.g. film printing, projection printing; by reflection of visible or UV light from an original such as a printed image using liquid photohardening compositions, e.g. for the production of reliefs such as flexographic plates or stamps
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70416—2.5D lithography

Definitions

  • the invention relates to a machine for manufacturing three-dimensional objects, generally prototype parts, by selective photopolymerization of liquids or powders by layers.
  • CAD computer aided design
  • the laser is generally controlled so as to solidify only part of the part to be produced (by drawing for example braces), in order to create a "load-bearing" structure, the rest of the resin then being solidified in a so-called "Post Curing” oven, with simple ultraviolet lamps.
  • a layer has been fully illuminated by the laser, all the parts of the liquid resin thus exposed have started a polymerization reaction.
  • a squeegee system comes to equalize the surface, the plate on which the workpiece is placed goes down one step in the liquid (not equal to the thickness of the layer to be solidified, i.e. generally 0.1 0.2 mm). The process is repeated until the complete production of the piece.
  • Direct connection via an interface to a surface or volume CAD file.
  • the aim of the invention is therefore to create an improved machine for manufacturing objects by selective photopolymerization of liquids or powders in layers, allowing much faster execution of these objects, avoiding some of the principles of existing machines mentioned above.
  • the stereolithography machine which it concerns uses, instead of the point method "laser” mentioned above, an "active” mask and a source of insolation of the liquid or the powder behind this mask.
  • It can be an ultraviolet source for the photopolymerizable resins currently available, or a source of other wavelength suitable for other resins that one would like to harden, or an active emissive source , such as video screens or laser diodes or plasma discharge tubes.
  • an active emissive source such as video screens or laser diodes or plasma discharge tubes.
  • the general principle applied is as follows: In order to solidify a layer of liquid, a mask is created. This mask represents the layer to be solidified.
  • the transparent part of the mask lets pass the photons of wavelength adapted to the resin which one wishes, to polymerize (wavelength ultraviolet in general, but being able to be different according to the resins used as indigué above
  • the photons which will touch the photopolymerizable liquid will allow the chemical reaction allowing the change of state "liquid / solid” .
  • the dark part of the mask prevents the passage of photons and therefore avoids solidification of the liquid in the corresponding area.
  • This mask is associated with an optical focusing device, exactly like a slide projector or overhead projector (Fresnel lens), each mask being in itself a kind of slide. This makes it possible to have a clear image on the surface of the liquid and to solidify only what must be.
  • the proposed stereolithography machine uses, according to the first aspect of the invention here considered, so-called “active” masks in the sense that they are directly activated by a computer and electronic system, to modify their state according to the layers to solidify.
  • So "active" masks can be emissive video screens, crystal devices liquids absorbing part of the radiation emitted by an ultraviolet or other source (devices of the liquid crystal screen or liquid crystal array type), or laser diode devices or emissive plasma discharge tubes (also of the laser diode screen type or plasma discharge tubes, or diode array or tube type).
  • this displays a direct image of the parts to be solidified (light part) and the parts not to solidify (opaque part of the screen).
  • the photons emitted by the screen must be adapted in frequency and intensity to the light-curing characteristics of the light-curing liquid resins used.
  • laser diodes placed in arrays it suffices to sweep the surface of the liquid by displacement of the array of diodes, by controlling their illumination in order to reconstitute the image necessary for the desired polymerization, these diodes having to work at wavelengths compatible with the photopolymerization characteristics of the photopolymerizable liquid resins used.
  • the "active" mask is a device of the liquid crystal screen type
  • this device is backlit by an ultraviolet lamp or a series of ultraviolet lamps, in the case of resins sensitive to ultraviolet radiation (or other type of lamp, depending on the resins used).
  • the radiation is focused by an optical device on the photopolymerizable resin, initially liquid.
  • a complete polymerization takes place at once of the entire desired surface, to form a complete layer.
  • the liquid crystal device itself is made up of several successive screens.
  • a single "active" mask of this type does not offer a contrast greater than 70% between the parts left transparent and those supposed to be opaque to radiation.
  • the transparent part representing a very weak attenuation of intensity (except general attenuation due to the use of the diaphragm) compared to the opaque parts, one obtains 89% of attenuation on the opaque parts compared to the transparent parts, with two screens, and 97% with three screens, which is in both cases sufficient to obtain a selective polymerization, as desired.
  • a liquid crystal device and conventional projection optics can be used, or more specifically, materials more transparent to more distant ultraviolet rays such as quartz may be used.
  • a diode or tube array can have several hundred or thousands of such diodes or tubes, like the arrays used in laser printers.
  • the diodes or tubes are arranged in a line, and the strip is controlled to display one line of image at a time, thus illuminating the resin along a line, either directly or with focusing by an optical device in order to increase the precision.
  • the bar is moved step by step, by translation or rotation, and the complete image of the layer to be solidified is transmitted to this bar, line by line, in synchronism with its movement of translation or rotation.
  • the image of each layer is transmitted at one time, without any movement.
  • the display modification of each layer is done directly, by controlling the "active" mask by means of a computer device, without mechanical manipulation.
  • the machine according to the invention making it possible to solidify the successive layers, can remain analogous to existing machines; in particular, the part being manufactured can rest on a slaved plate, movable vertically, which descends step by step into the liquid as and when said part is formed.
  • this principle requires a stabilization time of the liquid (a few seconds) between the solidification of two successive layers, and the passage of a squeegee to equalize the surface.
  • the window, forming a projection screen is initially positioned at the bottom of the tank filled with liquid resin, at a height just equal to the thickness of the first layer to be solidified (for example: 0.1 mm).
  • the "active" mask such as a video screen or liquid crystal device or laser diode device or plasma discharge tubes, displays the image of the first complete layer (or line in the case of diode arrays or the like).
  • the light source then turns on, with an intensity and a duration of lighting depending on the type of resin used, for example in the manner of a "flash" or a shutter system, which solidifies the first layer, which will become the bottom layer of the object.
  • the window is then raised by a height corresponding to the thickness of a layer (for example: 0.1 mm), the gap between this window and the first solidified layer remaining filled with liquid by the effect of the pressure. , without the need for leveling.
  • the mask displays the image of the second layer to be solidified, the light source again sends its radiation to solidify this second layer, and so on until the complete object is obtained.
  • the window is raised to the full height of the part to be manufactured, and the “active” mask device has finished its work, the formed part still being completely submerged in the liquid.
  • a plate fitted with lifting means initially located at the bottom of the tank, rises the finished part, fully solidified. This part is then removed from the tray, rinsed with an adequate solvent and made available.
  • the sizes of the objects that can be manufactured using the stereolithography machine according to the invention are not particularly limited, the optimum being between volumes of 300 mm per cube for the smallest machines, and standard machines of 600 to 1000 mm cube. Larger sizes are possible, possibly by multiplying the "active" masks or by moving a single mask, or, more judiciously, by successively illuminating several parts or zones of the object to be manufactured, using only a single fixed mask but combined with a special optical device, in particular with several mirrors, some of which are mobile, to selectively direct the radiation towards the different parts or zones of the object being manufactured.
  • this optical device With regard to precision and manufacturing, this is entirely linked to the precision of the lighting element, namely liquid crystal cell or pixel of the video screen, or even laser diode or discharge tube, multiplied by the magnification factor of the optical device.
  • This optical device also makes it possible to illuminate different parts of the surface to be solidified, and this in several times (example: a square of 30 centimeters on one side can be lit by nine successive "flashes” each covering a square of 10 cm on one side ; and in this case, the precision will be that of the 10 cm square side).
  • the precision of each point is: 200/1000 mm, that is: 0.2 mm for a magnification factor of 1 and 0.1 mm for a magnification factor of 1/2 (image reduction by a factor of 2).
  • this precision will be of the same order, according to the arrangement of the elements on the strip (in general from 300 to 600 points per inch, that is to say: 25.1 mm for 300 to 600 points); the direct precision with magnification factor of 1 is therefore 25.1 / 300 to 25.1 / 600, that is: 0.085 to 0.043 mm.
  • the precision of the stereolithography machines currently supplied by the various manufacturers is no better than 0.2 mm on small objects.
  • the machines currently available offer speeds of the order of a solidified layer every 40 seconds in average, this time being due, on the one hand, to the scanning speed of the laser, and on the other hand to the waiting time between layers (stabilization of the liquid and passage of the squeegee as explained above).
  • the machine object of the invention eliminates the time of laser tracing, the stabilization of the liquid and the passage of the squeegee.
  • the manufacturing time per layer can go to 2 seconds, for a polymerization of 0.1 mm deep, which makes it possible to produce an object 10 cm high, whatever its length, its width, and its average thickness, in 2000 seconds, or about 35 minutes.
  • the machine object of the invention is of a relatively low cost price, compared to the current costs of stereolithography machines, and it can affect the design offices of companies, even of small size, manufacturing objects in the following industrial fields: automotive, aeronautics, household appliances, engineering, IT, electricity, electromechanics, electronics, telephony, packaging, glass products, sports equipment, toys, eyewear, medical equipment ...
  • FIG. 2 is a block diagram of the stereolithography machine object of the invention, with its intended variants
  • Figure 3 is a schematic view illustrating various modes of design envisaged of an "active" or “passive” mask, in connection with the invention
  • Figure 4 is a vertical sectional view of a machine with mask based on liquid crystal screen
  • Figure 5 is a perspective view of a mask machine based on a liquid crystal array
  • Figure 6 illustrates a first possibility of po ⁇ sitioning the liquid crystal device of Figure 5
  • Figure 7 illustrates a second possibility of po ⁇ sitioning the liquid crystal device of Figure 5
  • Figure 8 is a perspective view of a mask machine based on a laser diode array or plasma discharge tubes
  • Figures 9 and 10 illustrate two possibilities for positioning the device with laser diodes or tubes of Figure 8;
  • Figure 11 is a vertical sectional view of a machine according to the invention with glass plunged into the resin tank;
  • Figure 12 shows a variant of the machine of Figure 11
  • Figure 13 is a perspective view showing a machine designed to produce large objects.
  • FIG. 2 which is a block diagram common to all the embodiments of the invention, 8 designates the light source, used with an "active" mask 9 of the liquid crystal screen type, or with a mask “active” 10 of the liquid crystal strip type.
  • 11 denotes an "active" mask of the video screen type
  • 12 denotes an “active” mask constituted by a device with laser diodes or plasma discharge tubes (in the form of a screen or strips), the latter "active masks”.
  • “It and 12 constituting by themselves the light source, therefore not requiring the intervention of the separate light source 8.
  • an optical focusing device 13 is interposed, which projects 1 • image of the mask on a window 14.
  • the tank 5 includes a tank bottom plate 15, movable vertically, which is actuated at the end of the process to take out the manufactured part (here not shown).
  • the assembly 16 comprising the possible light source 8, the "active" mask 9, 10, 11 or 12, the focusing optics 13 and the window 14 constitutes a vertically movable part, partially sinking into the tank 5.
  • the sub-assembly 17, constituted by the focusing device 13 and the window 14, is immersed (during operation) in the liquid resin 4 contained in the tank 5.
  • the mask makes it possible to define the part of the resin which must be solidified, in the tank 5, to form a horizontal layer of the object to be produced.
  • the image of this part, as it appears on a screen 18, is indicated in black at the top right of FIG. 3.
  • the various possible methods for solidifying selectively and in layers, the photopolymerizable resin, contained in the tank 5, are designated by the Roman numerals I to VI:
  • FIG. 4 shows, in more detail, a machine according to the invention with an "active" mask based on a liquid crystal screen, arranged horizontally.
  • a diffuser 23 Between the light source 8 and a first liquid crystal screen 9a is interposed a diffuser 23 ensuring a uniform distribution of the light.
  • a second liquid crystal screen 9b is also provided here, located below the first.
  • a first diaphragm 24 and a first focusing optic 25 Between the two liquid crystal screens 9a and 9b are disposed a first diaphragm 24 and a first focusing optic 25. Under the lower liquid crystal screen 9b are arranged a second diaphragm 26 and a second focusing optic 27. All these components are supported by the same frame 28.
  • a plate 14 made of glass or other material transparent to the wavelengths of the radiation used is secured to a sealed box 29, sinking into the liquid resin 4 contained in the tank 5.
  • the focusing optic 27 projects the image, formed by the two liquid crystal screens 9a and 9b, onto the window 14, with the possibility of enlarging or reducing this image.
  • the window 14 is raised.
  • the object formed is itself wound up, and extracted from the resin which has remained liquid, by displacement of the tank bottom plate 15.
  • FIG. 5 shows a machine with an "active" mask based on a liquid crystal strip, comprising a device 30 movable horizontally above the tank 5 according to arrow F, the device 30 comprising, in a manner analogous to 1 • previous example: the source light 8, a means 23 for uniform distribution of light, a first strip of liquid crystals 10a, a diaphragm system 24, a focusing lens system 25 and a second strip of liquid crystals 10b.
  • Horizontal guide rails 31 allow the translation of this device 30, over the entire useful length of the tank 5, to form "line by line” each layer of solidified resin, a device electronically controlled by the display of the line, controlling the translation of the device 30.
  • the "active mask” constituted by the device 30 previously detailed is placed directly in a sealed box 29 with transparent plate 14 at the bottom, which plunges into the resin 4 contained in the tank 5.
  • the device 30 based on a strip of liquid crystals is located outside of the tank 5, behind a focusing optic 13 of the "zoom" type with horizontal optical axis, a mirror 22 reflecting the image on the glass 14 of the waterproof box 29 which dips into the resin 4 contained in the tank 5.
  • FIGS. 8, 9 and 10 correspond respectively to FIGS. 5, 6 and 7, but illustrate a machine with an "active" mask based on a device with laser diodes or plasma discharge tubes, here more particularly a strip 12 of laser diodes or tubes. to discharge.
  • the assembly 32 constituted by the bar 12 and by the associated focusing optic 13 is movable in translation horizontally along the arrow F, along guide rails 31, over the useful length of the tank 5 containing the liquid resin 4.
  • FIGS. 9 and 10 illustrate the possibilities of positioning the assembly 32, that is to say in a sealed box 29 immersed in the resin 4, either externally with the interposition of a focusing optic 13 of the "zoom" type and of a deflection mirror 22.
  • FIG. 11 shows, more precisely, a machine according to the invention with window 14 forming the bottom of a sealed box 29 immersed in the resin 4, the “active” mask device (of any of the types previously described) being located outside, and forming an image which a focusing optic 13 and a deflection mirror 22 make it possible to project onto the submerged glass 14, rising gradually as the successive layers of the part 7 during manufacture.
  • FIG. 12 shows a variant without deflection mirror, but retaining a sealed box 29 with window 14 plunging into the tank 5 of photopolymerizable resin 4.
  • FIG. 13 represents a machine allowing large objects to be produced, the reference 7 designating the part already made of such a part, for example of great length, made in a tank 5 of elongated shape, filled with resin .
  • the “active” mask device for example with light source 8, liquid crystal screen 9, and focusing optic 13, is arranged externally.
  • a set of several mirrors 22a, 22b, 22c, some of which are pivotally mounted, makes it possible to send the images of the "active" mask alternately on several adjacent parts of the glass 14, therefore in different adjacent zones of the part being formed 7 , so as to produce the complete part by successively illuminating several parts into which each layer is divided.

Abstract

A stereolithography machine using an 'active' mask directly controlled by a computer device as a source for selectively photopolymerising liquid or powdered resins in order to produce three-dimensional objects on the basis of computer data. The 'active' mask enabling an entire resin layer to be cured in a single step is particularly a liquid crystal device (9, 10) combined with a light source (8), an emissive video screen (11) or a laser diode or discharge tube device (12). An image of the mask may be projected through a focusing lens (13) onto a sheet member (14) immersed in a vessel (5) filled with liquid resin (4).

Description

"Machine de fabrication d'objets par photopolymérisation sélective de liquides ou poudres par couches" "Machine for manufacturing objects by selective photopolymerization of liquids or powders by layers"
L'invention concerne une machine pour la fabrication d'objets tridimensionnels, généralement des pièces prototypes, par photopolymérisation sélective de liquides ou poudres par couches.The invention relates to a machine for manufacturing three-dimensional objects, generally prototype parts, by selective photopolymerization of liquids or powders by layers.
La notion de prototypage rapide par solidification d'une couche de résine liquide ou une poudre, dénommée par le terme "stéréolithographie", est apparue dans le milieu des années 1980, comme une nouvelle méthode de fabrication d'objets à partir de fichiers informatiques dits de conception assistée par ordinateur (CAO) . Cette technologie permet de réaliser les objets définis en CAO en mode surfacigue ou volumigue directement dans une résine photopolymérisable, sans usinage, par solidification d'un liquide ou d'une poudre.The concept of rapid prototyping by solidification of a layer of liquid resin or a powder, called by the term "stereolithography", appeared in the mid-1980s, as a new method of manufacturing objects from so-called computer files computer aided design (CAD). This technology allows objects defined in CAD to be produced in surface or volume mode directly in a photopolymerizable resin, without machining, by solidification of a liquid or a powder.
En matière de stéréolithographie, il existe aujourd'hui plusieurs systèmes permettant la solidification par couches successives de résines solides ou liquides, ou encore la création d'un objet par dépôt d'une couche de matériau fondu.In terms of stereolithography, there are today several systems allowing solidification by successive layers of solid or liquid resins, or even the creation of an object by depositing a layer of molten material.
Le système actuellement le plus répandu dans le monde est conçu et fonctionne comme suit : Par l'utilisation d'une source ultraviolette focalisée en un seul point, en pratique un laser, on polymérise par couches successives (grâce à un plateau descendant dans la résine liquide) et de manière sélective, une partie d'une résine photopolymérisable. Le laser, piloté par deux miroirs eux-mêmes asservis par un système informatique, balaye la surface du liquide avec une vitesse de traçage dépendant des miroirs de déviation. Le temps de traçage complet d'une couche est donc dépendant de la surface à solidifier. De plus le laser est en général piloté de façon à ne solidifier qu'une partie de la pièce à réaliser (en dessinant par exemple des croisillons), afin de créer une structure "portante", le reste de la résine étant ensuite solidifiée dans un four dit de "Post Curing", avec de simples lampes à ultraviolets. Lorsqu'une couche a été entièrement éclairée par le laser, toutes les parties de la résine liguide ainsi exposées ont amorcé une réaction de polymérisation. Ensuite, un système de raclette vient égaliser la surface, le plateau sur lequel est posée la pièce en cours de fabrication descend d'un pas dans le liquide (pas égal à l'épaisseur de couche à solidifier, soit en général de 0,1 à 0,2 mm). Le processus se répète ainsi jusqu'à la complète réalisation de la pièce. La figure 1 du dessin annexé rappelle le principe d'une telle machine : la y désigne le laser, lb le rayon laser, 2 un jeu de miroirs permettant d'orienter le rayon laser (en direction longitudinale et transversale d'un plan horizontal, 3 la raclette mobile en translation au-dessus de la surface de la résine liguide photopolymérisable 4 contenue dans une cuve 5, et 6 désigne le plateau descendant dans le liquide au fur et à mesure de la confection de la pièce 7 en cours de fabrication. Les avantages de cette technique par rapport aux méthodes classiques de réalisation d'objets (usinage par commande numérigue entre autres) sont les suivants : - Suppression de la nécessité de créer des parcours d'outil.The currently most widespread system in the world is designed and works as follows: By the use of an ultraviolet source focused at a single point, in practice a laser, we polymerize in successive layers (thanks to a plate descending in the resin liquid) and selectively, part of a photopolymerizable resin. The laser, controlled by two mirrors themselves controlled by a computer system, scans the surface of the liquid with a tracing speed depending on the deflection mirrors. The complete tracing time of a layer is therefore dependent on the surface to be solidified. In addition, the laser is generally controlled so as to solidify only part of the part to be produced (by drawing for example braces), in order to create a "load-bearing" structure, the rest of the resin then being solidified in a so-called "Post Curing" oven, with simple ultraviolet lamps. When a layer has been fully illuminated by the laser, all the parts of the liquid resin thus exposed have started a polymerization reaction. Then, a squeegee system comes to equalize the surface, the plate on which the workpiece is placed goes down one step in the liquid (not equal to the thickness of the layer to be solidified, i.e. generally 0.1 0.2 mm). The process is repeated until the complete production of the piece. FIG. 1 of the appended drawing recalls the principle of such a machine: the y designates the laser, lb the laser beam, 2 a set of mirrors making it possible to orient the laser beam (in the longitudinal and transverse direction of a horizontal plane, 3 the squeegee movable in translation above the surface of the light-curing resin 4 contained in a tank 5, and 6 designates the plate descending into the liquid as and when the part 7 is made during manufacture. The advantages of this technique compared to conventional methods of producing objects (machining by numerical control, among others) are as follows: - Elimination of the need to create tool paths.
Création complète de l'objet (intérieur et extérieur) simultanément.Complete creation of the object (interior and exterior) simultaneously.
- Capacité de réaliser d'un seul tenant des pièces non directement usinables.- Ability to produce parts that are not directly machinable in one piece.
- Rapidité relative de réalisation des pièces.- Relative speed of production of parts.
Connexion directe, via une interface à un fichier CAO surfacique ou volumique.Direct connection, via an interface to a surface or volume CAD file.
- Réalisation des pièces dans une résine spécifique. Comme déjà indiqué plus haut, cette technologie est actuellement largement diffusée dans le monde, auprès de nombreux utilisateurs, et pratiquement tous les fournisseurs de logiciels de conception assistée par ordinateur de type surfacique ou volumique disposent de l'interface adéquate, dénommmée interface "STL". Toutefois, ce procédé connu comporte encore des insuffisances. En particulier, la vitesse d'exécution des pièces est limitée, d'une part en raison de leur réalisation "point par point" (balayage laser) , et d'autre part en raison du principe utilisé de descente progressive de la pièce (portée par un plateau) en cours de fabrication, impliquant des temps intermédiaires de déplacement de cette pièce et d'attente de stabilisation de la surface du liquide, après chaque déplacement élémentaire de la pièce qui crée inévitablement des remous.- Production of parts in a specific resin. As already indicated above, this technology is currently widely distributed around the world, to many users, and practically all the suppliers of computer-aided design software of surface or volume type have the appropriate interface, called "STL" interface. . However, this known method still has shortcomings. In particular, the speed of execution of the parts is limited, on the one hand because of their "point by point" realization (laser scanning), and on the other hand because of the principle used for progressive descent of the part (range by a plate) during manufacture, implying intermediate times of movement of this part and waiting for stabilization of the surface of the liquid, after each elementary movement of the part which inevitably creates eddies.
Le but de 1'invention est donc de créer une machine perfectionnée de fabrication d'objets par photopolymérisation sélective de liquides ou poudres par couches, permettant une exécution beaucoup plus rapide de ces objets, en évitant certains des principes des machines existantes rappelées précédemment.The aim of the invention is therefore to create an improved machine for manufacturing objects by selective photopolymerization of liquids or powders in layers, allowing much faster execution of these objects, avoiding some of the principles of existing machines mentioned above.
Selon un premier aspect de la présente invention, la machine de stéréolithographie gu'elle concerne utilise, en lieu et place de la méthode ponctuelle "laser" rappelée ci-dessus, un masgue "actif" et une source d'insolation du liquide ou de la poudre située derrière ce masque. Il peut s'agir d'une source ultraviolette pour les résines photopolymérisables actuellement disponibles, ou d'une source d'autre longueur d'onde adaptée à d'autres résines que l'on souhaiterait durcir, ou encore d'une source active émissive, du type écran vidéo ou diodes laser ou tubes à décharge plasma. Dans tous les cas, le principe général appliqué est le suivant : Afin de solidifier une couche de liquide, on crée un masque. Ce masque représente la couche à solidifier. Plus particulièrement, la partie transparente du masque laisse passer les photons de longueur d'onde adaptée à la résine que l'on désire, polymeriser (longueur d'onde ultraviolette en général, mais pouvant être différente suivant les résines employées comme indigué ci-dessus. Les photons qui toucheront le liquide photopolymérisable vont permettre la réaction chimique permettant le changement d'état "liquide / solide". La partie sombre du masque empêche le passage des photons et donc évite la solidification du liguide dans la zone correspondante.According to a first aspect of the present invention, the stereolithography machine which it concerns uses, instead of the point method "laser" mentioned above, an "active" mask and a source of insolation of the liquid or the powder behind this mask. It can be an ultraviolet source for the photopolymerizable resins currently available, or a source of other wavelength suitable for other resins that one would like to harden, or an active emissive source , such as video screens or laser diodes or plasma discharge tubes. In all cases, the general principle applied is as follows: In order to solidify a layer of liquid, a mask is created. This mask represents the layer to be solidified. More particularly, the transparent part of the mask lets pass the photons of wavelength adapted to the resin which one wishes, to polymerize (wavelength ultraviolet in general, but being able to be different according to the resins used as indigué above The photons which will touch the photopolymerizable liquid will allow the chemical reaction allowing the change of state "liquid / solid" .The dark part of the mask prevents the passage of photons and therefore avoids solidification of the liquid in the corresponding area.
A ce masque est associé un dispositif de focalisation optique, exactement comme un projecteur de diapositives ou rétroprojecteur (lentille de Fresnel) , chaque masque étant en lui-même une sorte de diapositive. Cela permet d'avoir une image nette à la surface du liguide et de ne solidifier que ce qui doit l'être.This mask is associated with an optical focusing device, exactly like a slide projector or overhead projector (Fresnel lens), each mask being in itself a kind of slide. This makes it possible to have a clear image on the surface of the liquid and to solidify only what must be.
Différents types de masques sont envisageables, néanmoins, pour être compatible avec les vitesses de travail envisagées ainsi gue pour la souplesse du procédé, tout en les mentionnant, on ne retiendra pas les masgues de type : photographique, électrostatique par dépôt de couche de toner sur une vitre, traçage sur film transparent, traceur ou phototraceur, ces types de masques étant qualifiés de "statiques" ou "passifs" puisqu'il faut une intervention supplémentaire sur chaque masque pour le modifier (photographie à développer, toner à effacer puis redéposer, traçage d'un film par traceurs de différents types) . Au contraire, la machine de stéréolithographie proposée utilise, selon le premier aspect de l'invention ici considéré, des masques dits "actifs" en ce sens qu'ils sont directement activés par un système informatique et électronique, pour modifier leur état en fonction des couches à solidifier. Ainsi les masques "actifs" peuvent être des écrans vidéo émissifs, des dispositifs à cristaux liquides absorbant une partie du rayonnement émis par une source ultraviolette ou autre (dispositifs du type écran à cristaux liquides ou barrette de cristaux liquides) , ou des dispositifs à diodes laser ou tubes à décharge plasma émissifs (eux aussi du type écran à diodes laser ou tubes à décharge plasma, ou du type barrette de diodes ou tubes) .Different types of masks are possible, however, to be compatible with the working speeds envisaged as well as for the flexibility of the process, while mentioning them, we will not retain masgues of the type: photographic, electrostatic by depositing a layer of toner on a window pane, tracing on transparent film, plotter or phototracer, these types of masks being qualified as "static" or "passive" since it requires an additional intervention on each mask to modify it (photograph to be developed, toner to be erased then redeposited, tracing of a film by tracers of different types). On the contrary, the proposed stereolithography machine uses, according to the first aspect of the invention here considered, so-called "active" masks in the sense that they are directly activated by a computer and electronic system, to modify their state according to the layers to solidify. So "active" masks can be emissive video screens, crystal devices liquids absorbing part of the radiation emitted by an ultraviolet or other source (devices of the liquid crystal screen or liquid crystal array type), or laser diode devices or emissive plasma discharge tubes (also of the laser diode screen type or plasma discharge tubes, or diode array or tube type).
Ces masques "actifs" sont plus rapides que les masques qualifiés précédemment de "passifs", puisqu'ils sont pilotés directement et forment une image animée, dont les configurations successives correspondent aux couches successives à solidifier. Plus particulièrement :These "active" masks are faster than the masks previously described as "passive", since they are controlled directly and form an animated image, the successive configurations of which correspond to the successive layers to be solidified. More specifically:
Dans le cas de l'écran vidéo, celui-ci affiche une image directe des parties à solidifier (partie lumineuse) et des parties à ne pas solidifier (partie opaque de l'écran). Il est nécessaire que les photons émis par l'écran soit adaptés en fréquence et en intensité aux caractéristiques de photopolymérisation des résines liquides photopolymérisables utilisées. De même, dans le cas de diodes laser mises en barrettes, il suffit de balayer la surface du liquide par déplacement de la barrette de diodes, en pilotant leur éclairement afin de reconstituer 1'image nécessaire à la polymérisation souhaitée, ces diodes devant travailler à des longueurs d'onde compatibles avec les caractéristigues de photopolymérisation des résines liquides photopolymérisables utilisées.In the case of the video screen, this displays a direct image of the parts to be solidified (light part) and the parts not to solidify (opaque part of the screen). The photons emitted by the screen must be adapted in frequency and intensity to the light-curing characteristics of the light-curing liquid resins used. Likewise, in the case of laser diodes placed in arrays, it suffices to sweep the surface of the liquid by displacement of the array of diodes, by controlling their illumination in order to reconstitute the image necessary for the desired polymerization, these diodes having to work at wavelengths compatible with the photopolymerization characteristics of the photopolymerizable liquid resins used.
Dans tous les cas, on obtient une solidification rapide d'une couche, soit en solidifiant en une seule opération la totalité de la couche (cas de l'écran), soit en la solidifiant au cours d'un seul mouvement de balayage par translation ou rotation (cas de la barrette de diodes). En outre, le passage d'une couche à la suivante s'effectue instantanément, du point de vue du masque, par un pilotage de ce masque "actif". La conjugaison de ces particularités procure une grande rapidité d'exécution. Les écrans vidéo actuels, quels que soit leur définition, ont une faible composante ultraviolette, ce qui reste peu praticable en égard à 1'état actuel d'avancement des résines photopolymérisables, mais pourront néanmoins être utilisés, en tant que masques "actifs", pour toute résine se polymérisant à une longueur d'onde pouvant être émise par ce type d'écran, actuellement ou dans le futur. On peut envisager des écrans vidéo noir et blanc ou couleur. Lorsque le masque "actif" est un dispositif du type écran à cristaux liquides, ce dispositif est rétroéclairé par une lampe ultraviolette ou une série de lampes ultraviolettes, dans le cas de résines sensibles au rayonnement ultraviolet (ou autre type de lampe, en fonction des résines utilisées) . Le rayonnement est focalisé par un dispositif optique sur la résine photopolymérisable, initialement liquide. Comme dans le cas précédent de l'écran vidéo, il se produit une polymérisation totale et en une seule fois de toute la surface désirée, pour former une couche complète.In all cases, a rapid solidification of a layer is obtained, either by solidifying the entire layer in a single operation (case of the screen), or by solidifying it during a single translational sweeping movement. or rotation (case of the diode array). In addition, the transition from one layer to the next takes place instantaneously, from the point of view of the mask, by controlling this "active" mask. The combination of these features provides great speed of execution. Current video screens, whatever their definition, have a weak ultraviolet component, which remains impractical in view of the current state of progress of photopolymerizable resins, but can nevertheless be used, as "active" masks, for any resin polymerizing at a wavelength that can be emitted by this type of screen, currently or in the future. We can consider black and white or color video screens. When the "active" mask is a device of the liquid crystal screen type, this device is backlit by an ultraviolet lamp or a series of ultraviolet lamps, in the case of resins sensitive to ultraviolet radiation (or other type of lamp, depending on the resins used). The radiation is focused by an optical device on the photopolymerizable resin, initially liquid. As in the previous case of the video screen, a complete polymerization takes place at once of the entire desired surface, to form a complete layer.
Avantageusement, le dispositif à cristaux liquides est lui-même constitué de plusieurs écrans successifs. En effet, un seul masque "actif" de ce type n'offre pas un contraste supérieur à 70 % entre les parties laissées transparentes et celles censées être opaques au rayonnement. Pour augmenter de façon sensible le contraste entre les parties opagues et transparentes à la lumière ultraviolette ou autre, on monte donc au minimum deux écrans, et de préférence trois écrans à cristaux liquides l'un derrière l'autre, avec des optiques de focalisation entre eux ainsi que des diaphragmes. La partie transparente représentant une atténuation d'intensité très faible (sauf atténuation générale due à l'usage du diaphragme) par rapport aux parties opagues, on obtient 89 % d'atténuation sur les parties opaques par rapport aux parties transparentes, avec deux écrans, et 97 % avec trois écrans, ce qui est dans les deux cas suffisant pour obtenir une polymérisation sélective, telle que souhaitée.Advantageously, the liquid crystal device itself is made up of several successive screens. Indeed, a single "active" mask of this type does not offer a contrast greater than 70% between the parts left transparent and those supposed to be opaque to radiation. To significantly increase the contrast between the opaque and transparent parts to ultraviolet or other light, we therefore mount at least two screens, and preferably three liquid crystal screens one behind the other, with focusing optics between them as well as diaphragms. The transparent part representing a very weak attenuation of intensity (except general attenuation due to the use of the diaphragm) compared to the opaque parts, one obtains 89% of attenuation on the opaque parts compared to the transparent parts, with two screens, and 97% with three screens, which is in both cases sufficient to obtain a selective polymerization, as desired.
Le principe est le même dans le cas de l'utilisation de barrettes de cristaux liquides au lieu d'écrans. Des diaphragmes permettent alors d'affiner à la fois le contraste et la précision en augmentant la profondeur de champ.The principle is the same when using liquid crystal strips instead of screens. Diaphragms then make it possible to refine both the contrast and the precision by increasing the depth of field.
Suivant les longueurs d'onde utilisées, un dispositif à cristaux liquides et une optique classique de projection peuvent être utilisés, ou plus spécifiquement on pourra utiliser des matériaux transparents à l'ultraviolet plus lointain comme le quartz.Depending on the wavelengths used, a liquid crystal device and conventional projection optics can be used, or more specifically, materials more transparent to more distant ultraviolet rays such as quartz may be used.
Dans le cas de barrettes de diodes laser ou de barrettes de tubes à décharge plasma, une barrette de diodes ou tubes peut comporter plusieurs centaines ou milliers de diodes ou tubes de ce genre, à la manière des barrettes utilisées dans les imprimantes laser. Les diodes ou tubes sont disposées en ligne, et la barrette est commandée pour afficher une ligne d'image à la fois, éclairant ainsi la résine selon une ligne, soit directement, soit avec focalisation par un dispositif optique afin d'augmenter la précision. La barrette est déplacée pas à pas, par translation ou rotation, et l'image complète de la couche à solidifier est transmise à cette barrette, ligne par ligne, en synchronisme avec son mouvement de translation ou de rotation.In the case of laser diode arrays or plasma discharge tube arrays, a diode or tube array can have several hundred or thousands of such diodes or tubes, like the arrays used in laser printers. The diodes or tubes are arranged in a line, and the strip is controlled to display one line of image at a time, thus illuminating the resin along a line, either directly or with focusing by an optical device in order to increase the precision. The bar is moved step by step, by translation or rotation, and the complete image of the layer to be solidified is transmitted to this bar, line by line, in synchronism with its movement of translation or rotation.
Dans le cas d'un écran à diodes laser ou à tubes à décharge plasma, l'écran étant de dimensions définies supérieures à celles des couches à solidifier, l'image de chaque couche est transmise en une seule fois, sans aucun mouvement.In the case of a screen with laser diodes or with plasma discharge tubes, the screen being of defined dimensions greater than those of the layers to be solidified, the image of each layer is transmitted at one time, without any movement.
Dans tous les cas, la modification d'affichage de chaque couche se fait directement, par pilotage du masque "actif" au moyen d'un dispositif informatique, sans manipulation mécanique. Pour le reste, la machine selon l'invention, permettant de solidifier les couches successives, peut rester analogue à des machines existantes ; en particulier, la pièce en cours de fabrication peut reposer sur un plateau asservi, mobile verticalement, qui descend pas à pas dans le liquide au fur et à mesure de la formation de ladite pièce. Néanmoins, ce principe nécessite un temps de stabilisation du liquide (de quelques secondes) entre la solidification de deux couches successives, et le passage d'une raclette pour égaliser la surface.In all cases, the display modification of each layer is done directly, by controlling the "active" mask by means of a computer device, without mechanical manipulation. For the rest, the machine according to the invention, making it possible to solidify the successive layers, can remain analogous to existing machines; in particular, the part being manufactured can rest on a slaved plate, movable vertically, which descends step by step into the liquid as and when said part is formed. However, this principle requires a stabilization time of the liquid (a few seconds) between the solidification of two successive layers, and the passage of a squeegee to equalize the surface.
Afin d'augmenter la vitesse de fabrication de l'objet, il est proposé, selon un second aspect de la présente invention, de disposer l'image projetée par le masque "actif" et le dispositif optique non pas à la surface du liquide, mais à la surface d'une vitre en quartz ou autre matériau transparent aux longueurs d'onde utilisées, la vitre étant immergée dans le liquide et remontée au fur et à mesure de la formation de 1*objet à réaliser. On supprime ainsi le plateau descendant, le problème de stabilisation de la surface du liquide et le raclage, d'où une augmentation supplémentaire de la rapidité d'exécution des pièces, s'accompagnant en outre d'une simplification mécanique de la machine. En particulier, le liquide étant directement en contact avec la vitre, il n'y a pas de possibilité de vaguelettes à la surface du liquide, et tout problème d'effet de capillarité sur les parties nouvellement solidifiées est éliminé par construction, puisque tout reste dans le liquide.In order to increase the speed of manufacture of the object, it is proposed, according to a second aspect of the present invention, to have the image projected by the “active” mask and the optical device not on the surface of the liquid, but on the surface of a window made of quartz or other material transparent to the wavelengths used, the window being immersed in the liquid and raised as the object to be produced is formed. This eliminates the descending plate, the problem of stabilization of the surface of the liquid and the scraping, hence an additional increase in the speed of execution of the parts, further accompanied by a mechanical simplification of the machine. In particular, the liquid being directly in contact with the glass, there is no possibility of wavelets on the surface of the liquid, and any problem of capillary effect on the newly solidified parts is eliminated by construction, since everything remains in the liquid.
La machine complète, intégrant ce second aspect de l'invention, fonctionne comme suit :The complete machine, incorporating this second aspect of the invention, operates as follows:
La vitre, formant un écran de projection est positionnée initialement au fond de la cuve remplie de résine liquide, à une hauteur juste égale à l'épaisseur de la première couche à solidifier (par exemple : 0,1 mm). Le masque "actif", tel qu'écran vidéo ou dispositif à cristaux liquides ou dispositif à diodes laser ou tubes à décharge plasma, affiche l'image de la première couche complète (ou ligne dans le cas des barrettes de diodes ou autres). La source lumineuse s'allume alors, avec une intensité et une durée d'éclairage dépendant du type de résine utilisée, par exemple à la manière d'un "flash" ou d'un système à obturateur, ce qui solidifie la première couche, laquelle deviendra la couche inférieure de l'objet.The window, forming a projection screen is initially positioned at the bottom of the tank filled with liquid resin, at a height just equal to the thickness of the first layer to be solidified (for example: 0.1 mm). The "active" mask, such as a video screen or liquid crystal device or laser diode device or plasma discharge tubes, displays the image of the first complete layer (or line in the case of diode arrays or the like). The light source then turns on, with an intensity and a duration of lighting depending on the type of resin used, for example in the manner of a "flash" or a shutter system, which solidifies the first layer, which will become the bottom layer of the object.
La vitre est alors remontée d'une hauteur correspondant à l'épaisseur d'une couche (par exemple : 0,1 mm) , 1'interstice entre cette vitre et la première couche solidifiée restant rempli de liquide par l'effet de la pression, sans nécessité d'un nivellement. Le masque affiche alors l'image de la deuxième couche à solidifier, la source lumineuse envoie de nouvau son rayonnement pour solidifier cette deuxième couche, et ainsi de suite jusgu'à obtention de l'objet complet. En fin de processus, la vitre est remontée de la hauteur totale de la pièce à fabriquer, et le dispositif à masque "actif" a terminé son travail, la pièce formée se trouvant encore totalement immergée dans le liquide. Un plateau muni de moyens élévateurs, situé initialement au fond de la cuve, remonte la pièce terminée, entièrement solidifiée. Cette pièce est ensuite enlevée du plateau, rincée par un solvant adéquat et rendue disponible.The window is then raised by a height corresponding to the thickness of a layer (for example: 0.1 mm), the gap between this window and the first solidified layer remaining filled with liquid by the effect of the pressure. , without the need for leveling. The mask then displays the image of the second layer to be solidified, the light source again sends its radiation to solidify this second layer, and so on until the complete object is obtained. At the end of the process, the window is raised to the full height of the part to be manufactured, and the “active” mask device has finished its work, the formed part still being completely submerged in the liquid. A plate fitted with lifting means, initially located at the bottom of the tank, rises the finished part, fully solidified. This part is then removed from the tray, rinsed with an adequate solvent and made available.
Les tailles des objets fabricables au moyen de la machine de stéréolithographie selon 1' invention ne sont pas particulièrement limitées, l'optimum se situant entre des volumes de 300 mm au cube pour les plus petites machines, et des machines standard de 600 à 1000 mm au cube. Des tailles plus grandes sont envisageables, éventuellement en multipliant les masques "actifs" ou en déplaçant un masque unique, ou encore, plus judicieusement, en éclairant successivement plusieurs parties ou zones de l'objet à fabriquer, en n'utilisant qu'un seul masque fixe mais combiné avec un dispositif optique spécial, notamment à plusieurs miroirs dont certains sont mobiles, pour diriger sélectivement le rayonnement vers les différentes parties ou zones de l'objet en cours de fabrication.The sizes of the objects that can be manufactured using the stereolithography machine according to the invention are not particularly limited, the optimum being between volumes of 300 mm per cube for the smallest machines, and standard machines of 600 to 1000 mm cube. Larger sizes are possible, possibly by multiplying the "active" masks or by moving a single mask, or, more judiciously, by successively illuminating several parts or zones of the object to be manufactured, using only a single fixed mask but combined with a special optical device, in particular with several mirrors, some of which are mobile, to selectively direct the radiation towards the different parts or zones of the object being manufactured.
En ce qui concerne la précision et la fabrication, celle-ci est entièrement liée à la précision de l'élément d'éclairement, à savoir cellule de cristaux liquides ou pixel de l'écran vidéo, ou encore diode laser ou tube à décharge, multipliée par le facteur de grandissement du dispositif optigue. Ce dispositif optique permet par ailleurs d'éclairer différentes parties de la surface à solidifier, et ce en plusieurs fois (exemple : un carré de 30 centimètres de côté peut être éclairé par neuf "flashes" successifs couvrant chacun un carré de 10 cm de côté ; et dans ce cas, la précision sera celle du carré de 10 cm de côté) . Dans le cas d'un écran à cristaux liquides de 1000 points par 1000, et de 200 mm de côté, la précision de chaque point est de : 200/1000 mm, soit : 0,2 mm pour un facteur de grandissement de 1 et 0,1 mm pour un facteur de grandissement de 1/2 (réduction de 1'image d•un facteur 2) .With regard to precision and manufacturing, this is entirely linked to the precision of the lighting element, namely liquid crystal cell or pixel of the video screen, or even laser diode or discharge tube, multiplied by the magnification factor of the optical device. This optical device also makes it possible to illuminate different parts of the surface to be solidified, and this in several times (example: a square of 30 centimeters on one side can be lit by nine successive "flashes" each covering a square of 10 cm on one side ; and in this case, the precision will be that of the 10 cm square side). In the case of a liquid crystal display of 1000 points by 1000, and 200 mm on a side, the precision of each point is: 200/1000 mm, that is: 0.2 mm for a magnification factor of 1 and 0.1 mm for a magnification factor of 1/2 (image reduction by a factor of 2).
Dans le cas d'une barrette de cristaux liquides, de diodes ou de tubes à décharge, cette précision sera de même ordre, suivant la disposition des éléments sur la barrette (en général de 300 à 600 points par pouce, soit : 25,1 mm pour 300 à 600 points) ; la précision directe avec facteur de grandissement de 1 est donc de 25,1/300 à 25,1/600 soit : 0,085 à 0,043 mm. En comparaison, la précision des machines de stéréolithographie actuellement fournies par les différents constructeurs n'est pas meilleure que 0,2 mm sur des objets de petite taille.In the case of a strip of liquid crystals, diodes or discharge tubes, this precision will be of the same order, according to the arrangement of the elements on the strip (in general from 300 to 600 points per inch, that is to say: 25.1 mm for 300 to 600 points); the direct precision with magnification factor of 1 is therefore 25.1 / 300 to 25.1 / 600, that is: 0.085 to 0.043 mm. In comparison, the precision of the stereolithography machines currently supplied by the various manufacturers is no better than 0.2 mm on small objects.
En ce qui concerne la vitesse de travail, les machines actuellement disponibles offrent des vitesses de l'ordre d'une couche solidifiée toutes les 40 secondes en moyenne, ce temps étant dû, d'une part, à la vitesse de balayage du laser, et d'autre part au temps d'attente entre couches (stabilisation du liquide et passage de la raclette comme expliqué plus haut) . La machine objet de l'invention élimine le temps de traçage laser, la stabilisation du liquide et le passage de la raclette. Il en résulte que le temps de fabrication par couche peut passer à 2 secondes, pour une polymérisation de 0,1 mm de profondeur, ce qui permet de réaliser un objet de 10 cm de haut, quelles que soient sa longueur, sa largeur, et son épaisseur moyenne, en 2000 secondes, soit 35 minutes environ.Regarding the working speed, the machines currently available offer speeds of the order of a solidified layer every 40 seconds in average, this time being due, on the one hand, to the scanning speed of the laser, and on the other hand to the waiting time between layers (stabilization of the liquid and passage of the squeegee as explained above). The machine object of the invention eliminates the time of laser tracing, the stabilization of the liquid and the passage of the squeegee. As a result, the manufacturing time per layer can go to 2 seconds, for a polymerization of 0.1 mm deep, which makes it possible to produce an object 10 cm high, whatever its length, its width, and its average thickness, in 2000 seconds, or about 35 minutes.
De plus, la machine objet de l'invention est d'un prix de revient relativement bas, comparé aux coûts actuels des machines de stéréolithographie, et elle peut toucher les bureaux d'étude des entreprises, même de petite taille, fabriquant des objets dans les domaines industriels suivants : automobile, aéronautique, électroménager, ingénierie, informatique, électricité, électromécanique, électronique, téléphonie, emballage, produits verriers, matériel de sport, jouets, lunetterie, matériel médical...In addition, the machine object of the invention is of a relatively low cost price, compared to the current costs of stereolithography machines, and it can affect the design offices of companies, even of small size, manufacturing objects in the following industrial fields: automotive, aeronautics, household appliances, engineering, IT, electricity, electromechanics, electronics, telephony, packaging, glass products, sports equipment, toys, eyewear, medical equipment ...
De toute façon, l'invention sera mieux comprise à l'aide de la description qui suit, en référence au dessin schématique annexé représentant, à titre d'exemples non limitatifs, quelques modes de réalisation de cette machine de fabrication d'objets par photopolymérisation sélective de liquides ou poudres par couches :In any case, the invention will be better understood with the aid of the description which follows, with reference to the appended diagrammatic drawing representing, by way of nonlimiting examples, some embodiments of this machine for manufacturing objects by photopolymerization selective liquids or powders by layers:
Figure 2 est un schéma de principe synoptique de la machine de stéréolithographie objet de l'invention, avec ses variantes prévues ;Figure 2 is a block diagram of the stereolithography machine object of the invention, with its intended variants;
Figure 3 est une vue schématique illustrant divers modes de conception envisagés d'un masgue "actif" ou "passif", en liaison avec l'invention ; Figure 4 est une vue en coupe verticale d'une machine avec masque à base d'écran à cristaux liquides ; Figure 5 est une vue en perspective d'une machine à masque à base de barrette de cristaux liquides ;Figure 3 is a schematic view illustrating various modes of design envisaged of an "active" or "passive" mask, in connection with the invention; Figure 4 is a vertical sectional view of a machine with mask based on liquid crystal screen; Figure 5 is a perspective view of a mask machine based on a liquid crystal array;
Figure 6 illustre une première possibilité de po¬ sitionnement du dispositif à cristaux liquides de figure 5; Figure 7 illustre une seconde possibilité de po¬ sitionnement du dispositif à cristaux liquides de figure 5; Figure 8 est une vue en perspective d'une machine à masque à base de barrette de diodes laser ou tubes à décharge plasma ; Figures 9 et 10 illustrent deux possibilités de positionnement du dispositif à diodes laser ou tubes de figure 8 ;Figure 6 illustrates a first possibility of po¬ sitioning the liquid crystal device of Figure 5 ; Figure 7 illustrates a second possibility of po¬ sitioning the liquid crystal device of Figure 5 ; Figure 8 is a perspective view of a mask machine based on a laser diode array or plasma discharge tubes; Figures 9 and 10 illustrate two possibilities for positioning the device with laser diodes or tubes of Figure 8;
Figure 11 est une vue en coupe verticale d'une machine selon 1'invention avec vitre plongée dans la cuve de résine ;Figure 11 is a vertical sectional view of a machine according to the invention with glass plunged into the resin tank;
Figure 12 montre une variante de la machine de figure 11 ;Figure 12 shows a variant of the machine of Figure 11;
Figure 13 est une vue en perspective, représentant une machine conçue pour réaliser des objets de grande taille.Figure 13 is a perspective view showing a machine designed to produce large objects.
Sur la figure 2, qui est un schéma de principe commun à toutes les formes de réalisation de l'invention, 8 désigne la source d'éclairage, utilisée avec un masque "actif" 9 du type écran à cristaux liquides, ou avec un masque "actif" 10 du type barrette de cristaux liquides. En variante, 11 désigne un masque "actif" du type écran vidéo, et 12 un masque "actif" constitué par un dispositif à diodes laser ou tubes à décharge plasma (sous forme d'écran ou de barrettes), ces derniers masques "actifs" il et 12 constituant par eux-mêmes la source d'éclairage, donc ne nécessitant pas 1'intervention de la source d'éclairage séparée 8.In FIG. 2, which is a block diagram common to all the embodiments of the invention, 8 designates the light source, used with an "active" mask 9 of the liquid crystal screen type, or with a mask "active" 10 of the liquid crystal strip type. As a variant, 11 denotes an "active" mask of the video screen type, and 12 denotes an "active" mask constituted by a device with laser diodes or plasma discharge tubes (in the form of a screen or strips), the latter "active masks". "It and 12 constituting by themselves the light source, therefore not requiring the intervention of the separate light source 8.
Entre le masque "actif" 9,10,11 ou 12, d'une part, et la cuve 5 contenant la résine liquide photopolymérisable 4, d'autre part, est interposé un dispositif de focalisation optique 13, qui projette 1•image du masque sur une vitre 14. La cuve 5 comporte un plateau de fond de cuve 15, mobile verticalement, qui est actionné en fin de processus pour sortir la pièce fabriquée (ici non représentée) . L'ensemble 16 comprenant l'éventuelle source d'éclairage 8, le masque "actif" 9,10,11 ou 12, l'optique de focalisation 13 et la vitre 14 constitue une partie mobile verticalement, s'enfonçant partiellement dans la cuve 5. Le sous-ensemble 17, constitué par le dispositif de focalisation 13 et la vitre 14, est immergé (en cours de fonctionnement) dans la résine liquide 4 contenue dans la cuve 5.Between the “active” mask 9, 10, 11 or 12, on the one hand, and the tank 5 containing the photopolymerizable liquid resin 4, on the other hand, an optical focusing device 13 is interposed, which projects 1 • image of the mask on a window 14. The tank 5 includes a tank bottom plate 15, movable vertically, which is actuated at the end of the process to take out the manufactured part (here not shown). The assembly 16 comprising the possible light source 8, the "active" mask 9, 10, 11 or 12, the focusing optics 13 and the window 14 constitutes a vertically movable part, partially sinking into the tank 5. The sub-assembly 17, constituted by the focusing device 13 and the window 14, is immersed (during operation) in the liquid resin 4 contained in the tank 5.
Comme 1'illustre en complément la figure 3, le masque permet de définir la partie de la résine qui doit être solidifiée, dans la cuve 5, pour former une couche horizontale de l'objet à réaliser. L'image de cette partie, telle qu'elle apparaît sur un écran 18, est indiquée en noir en haut et à droite de la figure 3. Les différents procédés envisageables pour solidifier de façon sélective et par couches, la résine photopolymérisable, contenue dans la cuve 5, sont désignés par les chiffres romains I à VI :As illustrated in FIG. 3 in addition, the mask makes it possible to define the part of the resin which must be solidified, in the tank 5, to form a horizontal layer of the object to be produced. The image of this part, as it appears on a screen 18, is indicated in black at the top right of FIG. 3. The various possible methods for solidifying selectively and in layers, the photopolymerizable resin, contained in the tank 5, are designated by the Roman numerals I to VI:
(I) - Poudre déposée électrostatiquement sur un support transparent 19 par un dispositif 20 (masque "passif" non retenu par la présente invention) .(I) - Powder electrostatically deposited on a transparent support 19 by a device 20 ("passive" mask not retained by the present invention).
(II) - Diapositive ou film 21 interposé entre la source d'éclairage 8 et l'optique de focalisation 13 (autre genre de masque "passif" non retenu par la présente invention) . (III) - Dispositif à cristaux liquides, notamment écran à cristaux liquides 9 constituant un masque "actif".(II) - Slide or film 21 interposed between the light source 8 and the focusing optics 13 (another kind of "passive" mask not retained by the present invention). (III) - Liquid crystal device, in particular liquid crystal screen 9 constituting an "active" mask.
(IV) - Ecran vidéo 11 constituant un autre genre de masque "actif", incorporant sa source lumineuse.(IV) - Video screen 11 constituting another kind of "active" mask, incorporating its light source.
(V) - Dispositif à diodes laser ou tubes à décharge plasma 12. (VI) - Dispositif utilisant l'un des masques(V) - Device with laser diodes or plasma discharge tubes 12. (VI) - Device using one of the masks
"actifs" précédents 9,11 ou 12, mais disposé dans un plan vertical et non pas horizontal, et associé à au moins un miroir de renvoi 22, selon une disposition qui sera décrite plus en détail ci-après."active" preceding 9, 11 or 12, but arranged in a vertical plane and not horizontal, and associated with at least one deflection mirror 22, according to an arrangement which will be described in more detail below.
La figure 4 représente, plus en détail, une machine conforme à l'invention avec masque "actif" à base d'écran à cristaux liquides , disposé horizontalement. Entre la source lumineuse 8 et un premier écran à cristaux liquides 9a est interposé un diffuseur 23 assurant une répartition uniforme de la lumière. Il est encore prévu, ici, un deuxième écran à cristaux liquides 9b, situé au- dessous du premier. Entre les deux écrans à cristaux liquides 9a et 9b sont disposés un premier diaphragme 24 et une première optique de focalisation 25. Sous l'écran à cristaux liquides inférieur 9b sont disposés un second diaphragme 26 et une seconde optigue de focalisation 27. Tous ces composants sont supportés par une même monture 28. Une plaque 14 en verre ou autre matériau transparent aux longueurs d'ondes du rayonnement utilisé est solidaire d'un caisson étanche 29, s'enfonçant dans la résine liquide 4 contenue dans la cuve 5. L'optique de focalisation 27 projette l'image, formée par les deux écrans à cristaux liquides 9a et 9b, sur la vitre 14, avec possibilité d'agrandissement ou de réduction de cette image. Au fur et à mesure de la formation des couches de résine solidifiée, la vitre 14 est remontée. En fin de fabrication, l'objet formé est lui-même remonté, et extrait de la résine restée liquide, par déplacement du plateau de fond de cuve 15.FIG. 4 shows, in more detail, a machine according to the invention with an "active" mask based on a liquid crystal screen, arranged horizontally. Between the light source 8 and a first liquid crystal screen 9a is interposed a diffuser 23 ensuring a uniform distribution of the light. A second liquid crystal screen 9b is also provided here, located below the first. Between the two liquid crystal screens 9a and 9b are disposed a first diaphragm 24 and a first focusing optic 25. Under the lower liquid crystal screen 9b are arranged a second diaphragm 26 and a second focusing optic 27. All these components are supported by the same frame 28. A plate 14 made of glass or other material transparent to the wavelengths of the radiation used is secured to a sealed box 29, sinking into the liquid resin 4 contained in the tank 5. The focusing optic 27 projects the image, formed by the two liquid crystal screens 9a and 9b, onto the window 14, with the possibility of enlarging or reducing this image. As the solidified resin layers are formed, the window 14 is raised. At the end of manufacture, the object formed is itself wound up, and extracted from the resin which has remained liquid, by displacement of the tank bottom plate 15.
La figure 5 montre une machine avec masque "actif" à base de barrette à cristaux liquides, comportant un dispositif 30 mobile horizontalement au-dessus de la cuve 5 selon la flèche F, le dispositif 30 comprenant, d'une manière analogue à 1•exemple précédent : la source lumineuse 8, un moyen 23 de répartition uniforme de la lumière, une première barrette de cristaux liquides 10a, un système diaphragme 24, un système de lentilles de focalisation 25 et une seconde barrette de cristaux liquides 10b. Des rails de guidage horizontaux 31 permettent la translation de ce dispositif 30, sur toute la longueur utile de la cuve 5, pour former "ligne par ligne" chaque couche de résine solidifiée, un dispositif asservi électroniquement à l'affichage de la ligne, pilotant la translation du dispositif 30.FIG. 5 shows a machine with an "active" mask based on a liquid crystal strip, comprising a device 30 movable horizontally above the tank 5 according to arrow F, the device 30 comprising, in a manner analogous to 1 • previous example: the source light 8, a means 23 for uniform distribution of light, a first strip of liquid crystals 10a, a diaphragm system 24, a focusing lens system 25 and a second strip of liquid crystals 10b. Horizontal guide rails 31 allow the translation of this device 30, over the entire useful length of the tank 5, to form "line by line" each layer of solidified resin, a device electronically controlled by the display of the line, controlling the translation of the device 30.
Selon une première possibilité de positionnement, illustrée par la figure 6, le "masgue actif" constitué par le dispositif 30 précédemment détaillé est disposé directement dans un caisson étanche 29 avec plaque transparente 14 au fond, qui plonge dans la résine 4 contenue dans la cuve 5.According to a first possibility of positioning, illustrated by FIG. 6, the "active mask" constituted by the device 30 previously detailed is placed directly in a sealed box 29 with transparent plate 14 at the bottom, which plunges into the resin 4 contained in the tank 5.
Selon une autre possibilité de positionnement illustrée par la figure 7, le dispositif 30 à base de barrette de cristaux liguides est situé à l'extérieur de la cuve 5, derrière une optigue de focalisation 13 de type "zoom" avec axe optique horizontal, un miroir 22 renvoyant l'image sur la vitre 14 du caisson étanche 29 gui plonge dans la résine 4 contenue dans la cuve 5.According to another possibility of positioning illustrated in FIG. 7, the device 30 based on a strip of liquid crystals is located outside of the tank 5, behind a focusing optic 13 of the "zoom" type with horizontal optical axis, a mirror 22 reflecting the image on the glass 14 of the waterproof box 29 which dips into the resin 4 contained in the tank 5.
Les figures 8,9 et 10 correspondent respectivement aux figures 5,6 et 7, mais illustrent une machine avec masque "actif" à base de dispositif à diodes laser ou tubes à décharge plasma, ici plus particulièrement une barrette 12 de diodes laser ou tubes à décharge. L'ensemble 32 constitué par la barrette 12 et par l'optique de focalisation associée 13 est mobile en translation horizontalement selon la flèche F, le long de rails de guidage 31, sur la longueur utile de la cuve 5 contenant la résine liquide 4.FIGS. 8, 9 and 10 correspond respectively to FIGS. 5, 6 and 7, but illustrate a machine with an "active" mask based on a device with laser diodes or plasma discharge tubes, here more particularly a strip 12 of laser diodes or tubes. to discharge. The assembly 32 constituted by the bar 12 and by the associated focusing optic 13 is movable in translation horizontally along the arrow F, along guide rails 31, over the useful length of the tank 5 containing the liquid resin 4.
Comme précédemment, les figures 9 et 10 illustrent les possibilités de positionnement de l'ensemble 32, soit dans un caisson étanche 29 plongeant dans la résine 4, soit extérieurement avec interposition d'une optique de focalisation 13 de type "zoom" et d'un miroir de renvoi 22.As before, FIGS. 9 and 10 illustrate the possibilities of positioning the assembly 32, that is to say in a sealed box 29 immersed in the resin 4, either externally with the interposition of a focusing optic 13 of the "zoom" type and of a deflection mirror 22.
La figure 11 montre, de façon plus précise, une machine conforme à 1'invention avec vitre 14 formant le fond d'un caisson étanche 29 plongé dans la résine 4, le dispositif à masque "actif" (de l'un quelconque des types précédemment décrits) étant situé à l'extérieur, et formant une image qu'une optique de focalisation 13 et un miroir de renvoi 22 permettent de projeter sur la vitre immergée 14, remontant au fur et à mesure de la solidification des couches successives de la pièce 7 en cours de fabrication.FIG. 11 shows, more precisely, a machine according to the invention with window 14 forming the bottom of a sealed box 29 immersed in the resin 4, the “active” mask device (of any of the types previously described) being located outside, and forming an image which a focusing optic 13 and a deflection mirror 22 make it possible to project onto the submerged glass 14, rising gradually as the successive layers of the part 7 during manufacture.
La figure 12 montre une variante sans miroir de renvoi, mais conservant un caisson étanche 29 avec vitre 14 plongeant dans la cuve 5 de résine photopolymérisable 4.FIG. 12 shows a variant without deflection mirror, but retaining a sealed box 29 with window 14 plunging into the tank 5 of photopolymerizable resin 4.
Enfin, la figure 13 représente une machine permettant la réalisation d'objets de grande taille, le repère 7 désignant la partie déjà réalisée d'une telle pièce, par exemple de grande longueur, fabriquée dans une cuve 5 de forme allongée, remplie de résine. Un caisson étanche 29 avec vitre 14, de forme correspondante, plonge dans la cuve 5. Le dispositif à masque "actif", par exemple avec source lumineuse 8, écran à cristaux liquides 9, et optique de focalisation 13, est disposé extérieurement. Un jeu de plusieurs miroirs 22a, 22b, 22c, dont certains sont montés pivotants, permet de renvoyer alternativement les images du masque "actif" sur plusieurs parties adjacentes de la vitre 14, donc dans différentes zones adjacentes de la pièce en cours de formation 7, de manière à réaliser la pièce complète en éclairant successivement plusieurs parties en lesquelles chaque couche est divisée. Finally, FIG. 13 represents a machine allowing large objects to be produced, the reference 7 designating the part already made of such a part, for example of great length, made in a tank 5 of elongated shape, filled with resin . A watertight box 29 with window 14, of corresponding shape, plunges into the tank 5. The “active” mask device, for example with light source 8, liquid crystal screen 9, and focusing optic 13, is arranged externally. A set of several mirrors 22a, 22b, 22c, some of which are pivotally mounted, makes it possible to send the images of the "active" mask alternately on several adjacent parts of the glass 14, therefore in different adjacent zones of the part being formed 7 , so as to produce the complete part by successively illuminating several parts into which each layer is divided.

Claims

REVENDICATIONS
1. Machine de fabrication d'objets tridimensionnels par photopolymérisation sélective de liquides ou poudres par couches, dite machine de "stéréolithographie", permettant de solidifier par couches successives une résine photopolymérisable (4) liquide ou en poudre contenue dans une cuve (5) , à partir de fichiers informatiques, caractérisée en ce qu'elle comprend au moins un masque "actif" (9,10,11,12) directement activé par un système informatique et électronique, ce masque "actif" émettant, ou laissant passer sélectivement, un rayonnement lumineux de longueur d'onde adaptée à la résine à polymeriser, en affichant une image correspondant à une couche complète à solidifier ou à une ligne de cette couche.1. Machine for manufacturing three-dimensional objects by selective photopolymerization of liquids or powders by layers, known as a "stereolithography" machine, making it possible to solidify by successive layers a photopolymerizable resin (4) liquid or powder contained in a tank (5), from computer files, characterized in that it comprises at least one "active" mask (9,10,11,12) directly activated by a computer and electronic system, this "active" mask emitting, or letting pass selectively, light radiation of wavelength adapted to the resin to be polymerized, by displaying an image corresponding to a complete layer to be solidified or to a line of this layer.
2. Machine de stéréolithographie selon la revendication 1, caractérisée en ce que le masque "actif" est un dispositif à cristaux liquides (9,10) , absorbant une partie du rayonnement émis par une source lumineuse (8).2. Stereolithography machine according to claim 1, characterized in that the "active" mask is a liquid crystal device (9,10), absorbing part of the radiation emitted by a light source (8).
3. Machine de stéréolithographie selon la revendication 2, caractérisée en ce que le masque "actif" est constitué par au moins un écran à cristaux liquides (9 ; 9a,9b) . 3. Stereolithography machine according to claim 2, characterized in that the "active" mask consists of at least one liquid crystal screen (9; 9a, 9b).
4. Machine de stéréolithographie selon la revendication 2, caractérisée en ce que le masque "actif" est constitué par au moins une barrette de cristaux liquides (10 ; 10a, 10b), montée mobile en translation (flèche F) ou en rotation. 4. Stereolithography machine according to claim 2, characterized in that the "active" mask consists of at least one strip of liquid crystals (10; 10a, 10b), mounted movable in translation (arrow F) or in rotation.
5. Machine de stéréolithographie selon la revendication 3 ou 4, caractérisée en ce que le masque "actif" comprend au moins deux écrans à cristaux liquides (9a,9b) ou au moins deux barrettes de cristaux liquides (10a, 10b) disposés l'un derrière l'autre, des optiques de focalisation (25,27) ainsi que des diaphragmes (24,26) étant disposés entre ces écrans ou barrettes successifs (9a,9b ; 10a,10b) .5. Stereolithography machine according to claim 3 or 4, characterized in that the "active" mask comprises at least two liquid crystal screens (9a, 9b) or at least two bars of liquid crystals (10a, 10b) arranged on the one behind the other, focusing optics (25,27) as well as diaphragms (24,26) being arranged between these successive screens or bars (9a, 9b; 10a, 10b).
6. Machine de stéréolithographie selon la revendication 1, caractérisée en ce que le masque "actif" est un écran vidéo émissif (11) .6. Stereolithography machine according to claim 1, characterized in that the "active" mask is an emissive video screen (11).
7. Machine de stéréolithographie selon la revendication 1, caractérisée en ce que le masque "actif" est un dispositif à diodes laser ou à tubes à décharge plasma (12) . 7. Stereolithography machine according to claim 1, characterized in that the "active" mask is a device with laser diodes or plasma discharge tubes (12).
8. Machine de stéréolithographie selon la revendication 7, caractérisée en ce que le masque "actif" (12) est constitué par un écran à diodes laser ou à tubes de décharge plasma.8. Stereolithography machine according to claim 7, characterized in that the "active" mask (12) consists of a screen with laser diodes or plasma discharge tubes.
9. Machine de stéréolithographie selon la revendication 7, caractérisée en ce que le masque "actif"9. stereolithography machine according to claim 7, characterized in that the "active" mask
(12) est constitué par une barrette de diodes laser ou de tubes à décharge plasma, montée mobile en translation (flèche F) ou en rotation.(12) consists of a strip of laser diodes or plasma discharge tubes, mounted movable in translation (arrow F) or in rotation.
10. Machine de stéréolithographie selon l'une quelconque des revendications l à 9, caractérisée en ce qu'au masque "actif" (9,10,11,12) est associé un dispositif optique (13) de focalisation de l'image sur une plaque ou vitre (14) transparente au rayonnement utilisé, ladite plaque ou vitre (14) étant immergée dans la résine liquide (4) et remontée au fur et à mesure de la formation de l'objet à réaliser (7).10. Stereolithography machine according to any one of claims l to 9, characterized in that the "active" mask (9,10,11,12) is associated with an optical device (13) for focusing the image on a plate or window (14) transparent to the radiation used, said plate or window (14) being immersed in the liquid resin (4) and reassembled as the object to be produced (7) is formed.
11. Machine de stéréolithographie selon la revendication 10, caractérisée en ce que le dispositif (30, 32) à masque "actif" est positionné dans ou sur un caisson étanche (29) , dont la plaque ou vitre précitée11. Stereolithography machine according to claim 10, characterized in that the device (30, 32) with an "active" mask is positioned in or on a sealed box (29), the aforementioned plate or window
(14) constitue le fond.(14) constitutes the background.
12. Machine de stéréolithographie selon la revendication 10, caractérisée en ce que le dispositif (30,32) à masque "actif" est positionné extérieurement, une optique de focalisation (13) et au moins un miroir (22 ; 22a,22b,22c) étant prévus pour renvoyer l'image de ce dispositif à masgue "actif" sur la plaque ou vitre (14) du fond du caisson étanche (29) .12. Stereolithography machine according to claim 10, characterized in that the device (30,32) with an "active" mask is positioned externally, a focusing optic (13) and at least one mirror (22; 22a, 22b, 22c ) being intended to return the image of this "active" masked device on the plate or window (14) at the bottom of the sealed box (29).
13. Machine de stéréolithographie selon la revendication 12, caractérisée en ce gue pour la réalisation d'objets de grande taille, elle comprend un masque "actif" unique associé à un jeu de plusieurs miroirs (22a,22b,22c) , dont certains sont montés mobiles, permettant de diriger sélectivement le rayonnement vers différentes parties ou zones de l'objet (7) en cours de fabrication. 13. stereolithography machine according to claim 12, characterized in that for the production of large objects, it comprises a single "active" mask associated with a set of several mirrors (22a, 22b, 22c), some of which are mobile mounted, allowing to selectively direct the radiation towards different parts or zones of the object (7) during manufacture.
PCT/FR1993/001218 1992-06-05 1993-12-09 Machine for making objects by selectively photopolymerising layered liquids or powders WO1995015841A1 (en)

Priority Applications (2)

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FR9207158A FR2692053A1 (en) 1992-06-05 1992-06-05 Model prodn. by selective photopolymerisation of liq. or powder - using active liq. crystal mask or active light source controlled by computer instead of controlled movement focused laser
PCT/FR1993/001218 WO1995015841A1 (en) 1992-06-05 1993-12-09 Machine for making objects by selectively photopolymerising layered liquids or powders

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FR9207158A FR2692053A1 (en) 1992-06-05 1992-06-05 Model prodn. by selective photopolymerisation of liq. or powder - using active liq. crystal mask or active light source controlled by computer instead of controlled movement focused laser
PCT/FR1993/001218 WO1995015841A1 (en) 1992-06-05 1993-12-09 Machine for making objects by selectively photopolymerising layered liquids or powders

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