EP1039345A2 - Method for subtitling cinematographic films, especially on polyester based support - Google Patents

Abstract

Cleaning of cine films which have been subtitled by laser etching, by impinging a jet of steam and/or hot air onto the emulsion immediately after the etching procedure. Procedure for subtitling cinematographic films comprises etching graphical elements or text onto polyester or other film by means of a laser beam impinging on the film in the zone to be marked, wherein in a first stage etching is carried out using a laser beam with a rate of displacement of 1-200 (10-60) cm/sec and a power of 100 milliwatt - 20 (1-10) watt at the surface of the film, the ratio V/P between the rate of displacement in cm/second and the power at the level of the film in watts being 2-10 cm/second watt, and in a second stage the etched film is subjected to a finishing treatment to render the laser-etched zones of the subtitle transparent, using a jet of steam and/or hot air.

Description

Subject of the invention

The present invention relates to a method of subtitling of cinematographic films, in particular of the type polyester and triacetate, by a laser beam, in it showing a route corresponding to the subtitle to engrave.

State of the art

In documents GB-2036369-A and EP-0537068-B1, it has been proposed to carry out subtitling using a laser beam by first causing a transformation of the emulsion in the etched areas and in then subjecting the engraved film to a treatment corresponding to an area cleaning treatment engraved.

The cleaning treatment can be carried out by making a second pass of the laser beam in the same areas to be engraved with the film, in particular GB-2036369-A.

In the second of the documents cited, we also proposes that the cleaning treatment of the areas engraved is done by contact with a washing bath.

The second document proposes, in a first step, to carry out an engraving operation laser by applying a laser beam whose movement speed at the film level is between 1 cm / s and 200 cm / s and the power at the film level is between 100 milliwatt and 20 watt, the V / P ratio between the speed of movement expressed in cm / s and the film level power expressed in watts being understood between 10 and 30 and high enough for the beam laser performs a complete transformation of the emulsion in the engraved areas, causing heating, softening and dislocation of the emulsion without completely eliminate this emulsion transformed; and in a second step, to submit the engraved film with a treatment for cleaning the engraved areas ensuring elimination in the film areas previously marked by the low laser beam power, heated emulsion particles and dislocated by the laser beam thus revealing transparent subtitles.

It should be recalled that the V / P ratio is a way of expressing for a defined width of the line etched by the laser beam on the film, the reverse of the total energy applied per unit area.

The different practitioners of subtitling by laser beam have developed operating techniques which their own, especially for the choice of the V / P ratio depending on the nature of the emulsion support film. Some proceed in a single pass of the laser beam. Others offer a double operation or an operation multiple. In the latter process, the etching step limits the energy applied to the gelatin surface to unrealistic values and generally too weak, which leave variable colorations in the background of the subtitles according to the content of the image.

• la bordure noire autour de la lettre est enlevée, ce qui rend le sous-titre illisible sur les fonds clairs;
• suivant le contenu de l'image, et donc du niveau d'absorption de l'énergie du laser, les sous-titres placés dans des zones les plus sombres de l'image deviennent très transparents et à la limite éblouissants lors de la projection;
• la mise en contact avec un bain de lavage nécessite une machine supplémentaire équipée d'une armoire de séchage très importante, la gélatine étant très hygroscopique. Cette machine a un coût, de même que le personnel qui devra charger, surveiller, décharger et entretenir cette machine dite de "rewashing". Elle va également consommer de l'eau et le séchage va exiger une consommation appréciable d'électricité;
• de plus, un traitement de ce type engendre certains risques : griffures, séchage insuffisant avec comme conséquence le risque d'adhérence de la gélatine d'une spire contre le support de la spire précédente ou suivante lors de l'enroulement, ce qui détruirait la copie.

The cleaning step which follows the etching can be brought into contact with a washing bath, which brings many drawbacks, among which there may be mentioned:

• the black border around the letter is removed, making the subtitle illegible on light backgrounds;
• depending on the content of the image, and therefore on the level of absorption of the laser energy, the subtitles placed in the darkest areas of the image become very transparent and, in the end, dazzling during projection;
• contacting a washing bath requires an additional machine equipped with a very large drying cabinet, the gelatin being very hygroscopic. This machine has a cost, as well as the personnel who will have to load, monitor, unload and maintain this machine called "rewashing". It will also consume water and drying will require an appreciable consumption of electricity;
• in addition, a treatment of this type generates certain risks: scratches, insufficient drying with as a consequence the risk of adhesion of the gelatin of a turn against the support of the previous or next turn during winding, which would destroy the copy.

The appearance of polyester as a support has caused new difficulties that weren't known or rarely encountered for triacetate cellulose. This new medium is indeed more sensitive in the heat.

So we tried to use inputs reduced energy in the case of double passage or multiple passes or other measures to obtain satisfactory results, in particular by combining two laser beam passages with washing.

It should also be noted that in a way general, given the low energy efficiency of the laser source, the actual power consumption is a high multiple of the energy used for proper etching said. There is therefore a practical interest in reducing the energy consumed.

Aims of the invention

The invention generally aims to improve the conditions of subtitling in order to obtain better qualitative results, especially on support polyester.

It also aims to offer more economical operating conditions than solutions recommended by the cited state of the art.

Character-defining elements of the invention

According to the present invention, the aims are obtained by a film subtitling process cinematographic, according to which we engrave elements graphics or texts on a motion picture film from the polyester or other type using a laser beam traveling on the film the area to be marked and according to which, in a first step, we proceed to an operation of laser engraving by applying a laser beam whose film speed is between 1 cm / s and 200 cm / s and the power at level of the film is between 100 milliwatt and 20 watt, the total etching energy expressed by the V / P ratio between the speed of movement expressed in cm / s and the film level power expressed in watts being understood between 2 and 10 cm / s watt, and in a second step, we subjects the etched film to a finish treatment of the areas which have been etched by the laser beam, leaving appear transparent subtitles, using a jet of steam and / or hot air.

Description of a preferred embodiment of the invention

The present invention makes it possible to remedy the disadvantages of prior art solutions. She is presented as a two-step process.

It can be done using a separate processing machine for each step, namely a laser engraving unit for the first step and a separate unit consisting of a steam generator and / or hot humid air projecting water vapor and / or air hot humid on the film combined with a drying cabinet appropriate which can be small since the film is barely wet.

The two steps can however also take place almost simultaneously, on the same machine (essentially formed by the engraving unit laser), thereby saving energy, time, labor and a rewashing machine.

The process produces subtitles of best quality. Indeed, it leaves a black border around the letters, which greatly improves the ease for reading subtitles on clear backgrounds. Subtitles whose transparency is more regular (i.e. which no longer exhibit untimely coloring depending on the background of the image) are no longer as shiny on black backgrounds and no longer dazzle the viewer.

For the execution of the process, the first step is a laser engraving step obtained by the displacement of a laser spot focused on gelatin. The engraving can be done in one, two or more than two passes.

According to a preferred embodiment of the invention, the writing speed of the etching spot is between 10 and 60 cm / s, but this speed can increase significantly when passing a line to the other when the engraving is interrupted, in order to decrease the total execution time per image.

The power of the laser beam at the gelatin is preferably between 1 and 10 w.

The total energy of the etching operation in single pass or multiple pass, expressed by the V / P ratio, is between 2 and 10 cm / s.watt. This energy must be sufficient to completely transform the emulsion in carbonaceous residues eliminable by the device which will be described below, but not too high to prevent heat from processing gelatin does not affect the support of the film.

In a second step, the emulsion previously transformed into carbonaceous residues is subject to a jet of steam and / or hot humid air.

If you wish, you can do this use a device placed on the advance mechanism frame by frame of the engraving unit. If hot air and wet is used, it will advantageously be heated to a temperature between 20 and 100 ° C, the humidity of this air being between 50 and 100%.

The humid hot air supply pipe is preferably reheated so as to avoid any condensation and projection of droplets and advantageously, can be provided with a net whose propeller goes up towards the source of humid air, so also avoid the projection of water droplets on the film.

The advantage of using humid air is that the gelatin remains practically dry and the film can be rolled up immediately, without problems, and without additional operation. For more security, we can, if desired, blow dry hot air immediately after the humid air.

In addition, we can also provide a suction system for residues blown by the device described above.

The invention will be described in more detail in reference to the diagram of an installation such as shown in the accompanying figures.

Brief description of the figures

Figure 1 shows a schematic view a first type of installation suitable for setting up practice of the invention in which laser engraving and the finishing treatment is carried out in the same machine.

Figure 2 shows a view of a subtitle obtained by the process, under the conditions of Example 1, before (lower image) and after (image superior) treatment with moist air.

Figure 3 shows a variant of execution using a laser engraving unit and a separate unit for finishing treatment.

In Figure 1, a installation comprising the usual constituent elements for laser subtitling.

Laser engraving equipment 1 emits a laser beam to burn text on film 3 coming from a winder-unwinder system (defiler) 5. The film is guided and driven to a mechanism frame by frame 9.

Conventionally, the mechanism of image by image advancement comprises a drum 11 and four rollers 13. The film is entrained between the drum 11 and the two upper rollers 13 then returned, image by image, in front of an exhibition window 15. She then returns between the drum 11 and the two rollers lower 13 to finally return to the system rewinder-unwinder 5.

Conventionally, during a first step of writing the subtitles by laser beam, the spot laser is derived in X and Y and controlled in intensity "everything or nothing "by an acousto-optic modulator, all under the control of a computer.

The speed of the writing spot at the film is between 10 and 60 cm / s, and the power of the laser spot at film level is between 1 and 10 watt.

The diameter of the writing spot is included between 30 and 100 µm.

The writing of the subtitle can be done in single, double or multi-pass depending on the hardness of the gelatin and the total etching energy at the emulsion is limited between 2 and 10 cm / s.watt.

According to the invention, a second step, which can be called revelation of the subtitle, is produced by a device 17 mounted immediately after the exposure window 15.

This device blows moist air, de-oiled and dusted, on gelatin. The temperature of this air is between 20 and 100 ° C and its degree humidity between 50 and 100%.

The humid air supply line can have a diameter of 4 mm and carries a net whose propeller goes up towards the humid air source, in order to avoid that water droplets are sprayed onto the gelatin. This tubing may include an electrical resistance which also heats this air.

Before winding, we blow air hot and dry on film 3 by passing it in front one or more blowing heads 21, which ensures a perfect drying which prevents moisture from remaining harmful in gelatin.

The device 23 preferably comprises a air extraction device containing residues carbonaceous and therefore ensures both drying and the suction of these residues which can be separated by filtration.

An air conditioning unit 23 provides the supply of devices 17 and 21. The air injected by the device 17 is of course moistened before its use.

The technique is also applicable to a finishing treatment based on the use of steam of water.

According to the variant shown in FIG. 3, the film etched by a laser beam as it passes between a take-up reel 31 and a take-up reel 33 pass in front of a jet of steam or hot humid air 35 product by a steam or hot air generator 37 before enter a separate drying cabinet 39.

The principle of the invention is applicable to all types of supports (triacetate, polyester) and all film formats (16, 35 or 70 mm).

We can use a diode laser called semiconductor laser with a power of 5 watt. Such laser could be placed directly in the housing deflection.

The invention will be described in more detail in reference to embodiments illustrated by following examples.

Example 1

AGFA CP 20 film (polyester base) is engraved in double pass with a writing speed of 25 cm / s per pass in an installation like this illustrated in figure 1.

The power of the laser - semiconductor is 2.6 watts at the film level.

The diameter of the laser spot is set at 65 µm and the total etching energy corresponds to a V / P ratio 5 cm / s.watt.

The air used is at a temperature of 37 ° C. The humidity is 90%. The diameter of the tubing blowing air is 4 mm, the distance from the film being 20 mm.

We can provide a reverse pitch thread going up towards the source of humid air to avoid condensation in droplets towards the film.

If we compare with a rewashing machine conventional, which runs at 30 m / min, the time saved for the complete operation of subtitling is 30 min per coil of 600 m.

According to the invention, a black border is obtained surrounding the letters of the engraved text.

Generally, the subtitles are easier to read in light areas than is not the case with conventional techniques.

Example 2

A film engraved using a laser beam is subjected during its circulation between a coil debtor 31 and a take-up reel 33 for a few seconds to a steam jet at 100 ° C. He is sent then directly into the volume drying cabinet 39 reduced and at a lower temperature compared to what is usual for so-called classic "rewashing" machines.

Claims (13)

Film subtitling process cinematographic, according to which we engrave elements graphics or texts on a motion picture film from the polyester or other type using a laser beam traveling on the film the area to be marked and according to which, in a first step, we proceed to an operation of laser engraving by applying a laser beam whose film speed is between 1 cm / s and 200 cm / s and the power at level of the film is between 100 milliwatt and 20 watt, the V / P ratio between the speed of movement expressed in cm / s and the power at the film level expressed in watt being between 2 and 10 cm / s watt, and in a second step, the etched film is subjected to a finishing treatment areas that have been etched by the laser beam, revealing transparent subtitles, characterized in that the finishing treatment is carried out using a jet of steam and / or hot air. Method according to claim 1, characterized in that the first step is a step of laser engraving by moving a focused laser spot on gelatin, the etching being carried out in one, two or more than two passes. Method according to claim 2, characterized in that the writing speed of the spot of engraving is between 10 and 60 cm / s. Method according to any one of previous claims, characterized in that the laser beam power at the gelatin is between 1 and 10 W. Method according to any one of previous claims, characterized in that the energy total of the engraving operation in single pass or in multiple pass, expressed as the V / P ratio, is included between 2 and 10 cm / s watt. Method according to any one of Claims 1 to 5, characterized in that the gelatin previously transformed into carbonaceous residues in the first stage is subjected in a second stage to a jet steam and / or hot humid air using a device placed on the frame advance mechanism of the engraving unit. Method according to any one of claims 1 to 5, characterized in that one uses a finishing processing unit separate from the film engraving. Method according to any one of previous claims, characterized in that uses a humid air jet heated to a temperature between 20 and 100 ° C, the humidity of this air being between 50 and 100%. Method according to claim 6 or 7, characterized in that hot, dry air is blown over the film immediately after the action of the air jet hot humid. Method according to claim 8 or 9, characterized in that a heating of hot humid air just before it gets on the gelatin in order to avoid condensation in droplets. Method according to any one of previous claims, characterized in that vacuum the residues blown by the jet of steam and / or hot humid air or the air jet of drying. Application of the method according to one any of the preceding claims when engraving subtitles on all types of media (triacetate, polyester) and all film formats (16, 35 or 70 mm). Etched products obtained by the process of any of claims 1 to 11, characterized by a black border surrounding the letters of the engraved text and better readability in light areas.

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