US2600469A - Exposure apparatus for photographic contact printing on rotary cylinders - Google Patents

Description

June 17, 1952 T P. c. BREUERS ET AL 2,600,469

HICS CONTACT ER EXPOSURE APPARATUS FOR PHOTOGRAP PRINTING ON ROTARY CYLIND Filed Aug. 31, 1948 //v VE/V rags Patented June 17, 1952 UNITED STATES PATENT OFFICE EXPOSURE APPARATUS FOR PHOTO- GRAPHIC CONTACT PRINTING N ROTARY CYLINDERS Application August 31, 1948, Serial No. 47,004 In the Netherlands September 3, 1947 16 Claims. 1

The invention relates to an exposure apparatus for photographic contact printing on a translucent (i. e., light pervious or transparent) cylinder rotatingabout a light source, whichcylinder is provided with a devicefor keeping the leading end of the original under control. An apparatus as broadly referred to in those terms is known already.

With the known apparatus the device for keeping the leading end of the original under control consists of a mechanically operatin pincer or gripping device. In practice this gripping device presents some drawbacks. One of these consists in that interruptions are very apt to occur. A second drawback-is that it takes up much space on the cylinder circumference, this space being lost to exposure, which results in loss of paper. A third drawback is that operation (to introduce or apply the original and/or to replace a preceding by a fresh original) becomes dlfilCLllt with apparatus in which alarge part of the cylinder circumference is used for exposure, so that only a small zone is left in which the manipulations of introduction and removal (application and discharge) can be eifected.

A fourth drawback consists in that in holding the paper a pincer or grippin device sometimes creates lag (bulging spaces) in the original, for example at one or more of the edges, as a result of which the copies will be less sharp.

With the known apparatus the original is properly held, irrespective of whether it is pressed against the cylinder by the light-sensitive material or not. This renders the apparatus suitable for making more than one copy of the same original in immediate succession. In fact, it is for this very case that a holding device is required in order to hold the original on the cylinder, after it has passed through the zone of contact with exposed paper, until it comes into contact again with fresh unexposed paper. However, the mechanically operatin pincer or grippingdevice of the known apparatus is by no means capable of bringing the leading end of the original within its reach, i. e. attracting it.

In the same way, during removal of the-original (after exposure) this device simply releases it, but it does not contribute in any way to the actual-discharge movement of the original.

This removal of an original enveloping a cylinder calls for another diliicult manipulation. For this purpose use is frequently made of lifting devices, for example in'the form of a brush. These do not operate in a reliable manner. Besides, they cannot replace the holding device.

This invention makes it possible to satisfy all the requirements at the same time and meet the existing drawbacks. It provides a universal apparatus with which it is possible to make both large series of copies of one and the same original in succession and smaller numbers of copies of different originals, and even series of copies of several originals in succession.

An apparatus according to the invention operates in a very reliable manner and requires little expert attendance. Nevertheless it is very simple. For this purpose, according to the invention the cylinder body is provided with air ducts opening into the exterior surface of the cylinder and connected to an air-displacement system.

It has been found that with such a device the original can be held sufiiciently firmly on the cylinder (by suction) through the range where the original is not pressed against the cylinder by the material to be exposed (i. e. between the points-of removal and of introduction of this material; naturally it is also sufficient when the suction is restricted to this range) without any practically detrimental displacement, i. e. shifting of this original on the cylinder, taking place during the cylinder rotation. With the apparatus according to the invention registering of the original with the cylinder remains in practice sufficiently exact, even aftera large number of revolutions, to permit the (e. g. electrical) synchronization of additional operations, such as cutting, folding and the like to be controlled from the cylinder.

According to the invention the air ducts may communicate periodically .or continuously at the inner wall of the cylinder with a stationary air chamber connected with the air-displacement system.

With the known apparatus above referred to the holding device there used can be controlled automatically. For this, however, relatively complicated, vulnerable equipment requiring upkeep (lubrication) is necessary. With an apparatus according to the invention such automatic control is very simple. In fact, according to the invention the air-displacement system may .be controlled (naturally in a very simple and reliable manner) dependent on the cylinder rotation, either by interruption of the air-displacement (connecting and disconnecting) or by changing overfrom pressure to vacuum or conversely (from suction to blowing).

In the drawing an embodiment of the invention is illustrated diagrammatically in cross-section following the path of the material to be exposed.

In the drawing, I is a rotatable glass cylinder containing the tubular lamp 2.

A web 3 of the material to be exposed, e. g. di azotype paper, is passed from the bobbin 4 with the aid of the drawing roller 5 at the end of the exposure apparatus, via the rollers 5 and I, over the long arc on either side of the radii 8 and 5 around the exposure cylinder I and the sheetlike original I3 on the latter, and subsequently over the rollers I I and I2 in the direction of the arrows. Cylinder I and original It also move in the direction of the arrows.

After having passed the drawing roller 5, the web may be cut into pieces of the desired length by knives I3, whereupon the pieces are developed in developing apparatus I4, dried, deposited at I5 and folded, if necessary.

A braking arrangement I 6 on the bobbin 4 creates tension in the light-sensitive web, thus bringing about the applying pressure between the latter and the cylinder I. Consequently, the original I0, wherever it may be turning in the longer stretch on either side of the radii 8 and 9, is pressed against the cylinder under the tension of the web 3. Now if several copies of the same original are to be made successively, the original should be able to pass through the shorter stretch between the radii 8 and 9. If it passed through without being controlled further, however, the leading end of the original would be able to lift itself from the cylinder face, and in consequence of this the leading edge of the original (and at the same time the whole of the original) would undergo a slight displacement (shifting) when this leading edge entered again between web and cylinder at 8. In practice this is often the case. With a larger number of revolutions (a large number of copies of the same original) a slight displacement per revolution would result in a large total displacement of the original.

As has been described above, displacement of the original is undersirable (for example because the synchronism between the cylinder I and the copies is lost). In the apparatus according to the invention the displacement is obviated with the aid of a suction air current on the leading end of the original in the stretch of the small are between the radii 9 and 8. This suction current is maintined in this stretch by a row of air ducts I1 parallel to the axis and forming suction apertures or orifices in the outer wall, these ducts connecting the outer wall of the cylinder with its inner wall, where they open into a stationary air chamber I8, which fits into the inner wall of the cylinder. Thus, as the ducts pass over the chamber I8, which extends at either side over part of the span in which web 3 applies tension, suction is obtained through a somewhat larger distance than the stretch of the smaller are between the radii 9 and B. Suction on the leading edge of the original to bridge this stretch is quite sufficient to obviate displacement of the original.

The leading marginal strip of the original exactly covers the row of suction orifices. The row of ducts may, of course, be replaced by a single, for example, a slotlike channel, by a row of ducts having a common slotlike suction orifice in the outer surface, or the like. Nor is it necessary, of course, for the air passage to lead to the inner wall, it may also lead to the outer edges or ends of the cylinder.

When the desired number of copies of a given original has been made, the air suction may be interrupted and the original may be removed by hand from the cylinder. For practical operation, however, it is more convenient to change the suction current into a blowing-air current, which strips the original ofi the cylinder. The original then may pass, for example via a guide I9 and with the aid of blowing-air at 20, to a receptacle 2I into which the copied originals are discharged successively.

In the meantime the part of the cylinder surface which held the leading margin of the removed original becomes available promptly upon passing radius 9 to take hold of a fresh original. This can be applied to it by hand by putting the leading margin of the fresh original within reach of the air-ducts at I! or, as has been illustrated in the drawing, it can be applied mechanically. For that purpose a shield or backward guide extension 22 is provided having an underneath abutment 24 to prevent premature delivery of the fresh original 25, and having openings 23 back of the abutment through which a disc roller 28 carrying fingers or lips 21 may descend at a desired moment to press the leading edge of the fresh original 25 beyond the abutment 24. As described more in detail below this action can take place synchronously with the cylinder rotation. When the leading edge has been displaced from abutment 24 the original 25 rests under the pressure of fingers 21 on the moving light-sensitive web 3; so that it is carried along by the web underneath the abutment 24 to cylinder I, being guided toward a position between the cylinder surface and the web on roller I by means of a guide 22. The finger 21 is swingable laterally on its supporting roller 26 to move free of the displaced sheet as the web advances the sheet onward.

With correct synchronization of the coming into operation of the said apply device, the leading edge of the original will cover the air ducts exactly. This and similar applying devices are capable of working so accurately that no special abutment is required on the cylinder. However, if the original is introduced by hand, it is of advantage to provide an abutment 28 on or in the cylinder near the air ducts II.

In the drawing, cylinder I need not be driven; it is drawn along sufficiently by web 3, which is moved continuously by roller 5. Synchronization of operations such as the removal and introduction of originals, may then be controlled by the cylinder itself (for example by means of electric contacts), while other operations, such as cutting at I3, may also be controlled by the cylinder. In this connection it is essential to prevent displacement of the original, as made possible according to the present invention, when the original is to remain on the cylinder during a number of revolutions for the successive making of a large number of copies.

The apparatus according to the drawing may also be used for making a series of single copies of a number of originals, say 30 of them, in such a way that it delivers the copies in the order of the originals. To this end the apparatus is operated as follows:

The 30 originals (numbered 1-30) lie ready in the correct order. The mechanism with which the cylinder I controls the introduction mechanism 22, 23, 24, 26, 21 during its rotation is so adjusted that with every revolution of cylinder I one original is placed with its leading end within reach of the mouth of the air ducts Ii. The operation is started with original No. 30 and this is placed in the position of original 25 in the 7. In a photographic contact printing apparatus, a hollow light pervious exposure cylinder rotatable about a light source therewithin to move its outer surface and sheet material thereon through an exposing path from a fixed sheet applying zone to a fixed sheet removal zone and then through a shorter return path spanning said zones, radial air ducts through the body of the cylinder opening at said surface and distributed thereon in a line substantially parallel to its axis, and airdisplacement means including a stationary air chamber fitting the inner surface of the cylinder and communicating with said line of air ducts only as the same moves through said return path.

8. In a photographic contact printing apparatus, a light pervious exposure cylinder rotatable about a light source therewithin to move its outer surface through an exposing path over most of its circumference, between closely spaced sheet applying and sheet removal zones at said surface, and then through a return path spanning said zones, means extending into said applying zone for leading a sheet to said surface therein, means respectively for leading a continuous flexible web to said surface at the applying zone and for withdrawing the Web under tension at said removal zone, the web passing about said surface under tension and pressing against it so that the web and cylinder move together through said exposing path for exposure of a sheet therebetween, air duct means in the light pervious body of the cylinder opening to said surface and distributed thereon along a generating line thereof, and an air displacement system communicating with said duct means at least as the same move in said return path for applying either suction or air pressure through the duct means to the leading margin of a sheet in said return path.

9. In a photographic contact printing apparatus, a light pervious exposure cylinder rotatable about a light source therewithin to move its outer surface through an exposing path over most of its circumference, between fixed sheet applying and sheet removal zones at said surface, and then through a shorter return path spanning said zones, a Web guide adjacent said surface at each of said zones, means respectively for supplying a continuous web of light-sensitive printing material to the applying zone web guide and for withdrawing the web under tension from the removal zone web guide, the web passing from the applying zone web guide about said surface through said exposing path and thence over the removal zone web guide to said withdrawing means and pressing against said surface so that the cylinder is rotated by movement of the web, air duct means in the light pervious body of the cylinder opening to said surface and arranged thereon along a generating line at a limited circumferential part thereof, and an air displacement system including means for applying through said duct means as the same move in said return path either suction to hold the leading margin of. a sheet to said surface or air pressure to blow such margin from said surface.

10. In an apparatus as described in claim 9, a sheet guide extending into said applying zone in spaced relation to said web guide, a stop ahead of said sheet guide and over a portion of said web approaching the cylinder to abut the lead-' ing edge of a sheet passed toward said zone, and

. from said stop and into contact with said a sheet displacing device movable to depress such web portion so that the latter will advance the displaced sheet beneath said stop to the cylinder.

11. An apparatus as described in claim 9, said displacing device comprising finger means depending from and swingable laterally on a support so that the displaced sheet may advance without restriction from said device.

12. An apparatus as described in claim 9, and a sheet guide extending from said removal zone and spaced from the web guide therein in position to engage said leading margin when it is blown from the cylinder surface and then direct the sheet away from said surface as the cylinder continues rotating.

13. An apparatus as described in claim 12, and air projection means associated with said sheet guide for blowing a released sheet thereon to a collection point.

14. In a photographic contact printing apparatus comprising a light pervious exposure cylinder rotatable about a light source therewithin for exposure of sheet material about its outer surface, means respectively for supplying a web of light sensitive printing material to and for withdrawing the web under tension from the outer surface of said cylinder, said means being operative to rotate the cylinder by movement of the web and being arranged so that the web extends about said surface between the said means through an exposing path covering most of the circumference of said surface, there being a gap at said surface between portions of the web approaching and leaving the same, air duct means in the light pervious body of the cylinder opening to said surface and distributed thereon along a generating line thereof, and an air displacement system including means for applying suction through said duct means to the leading margin of a sheet on said surface as the duct means and such margin move through said gap.

15. An apparatus as described inclaim 10, said air displacement system including means for applying compressed air through said duct means as they move in said gap so as to blow the leading margin of an exposed sheet away from said surface. s

16. In a photographic contact printing apparatus, a light pervious exposure cylinder rotatable about a light source therewithin and of a size to hold but a single original sheet entrained about its outer surface, means for delivering a web of light-sensitive printing material against said surface at a fixed sheet applying zone and means for withdrawing the web under tension from said surface at a fixed sheet removal zone near said applying zone, the web passing about said surface in the longer path between said zones and said means holding it taut against said surface so that movement of the web rotates the cylinder, means in said applying zone for guiding the leading margin of a sheet to the cylinder between said surface and the approachingweb portion so that the sheet may be entrained and exposed about the cylinder between it and the web by movement of the web, guide means in said removal zone spaced from said surface and from the departing web portion to engage and lead away from the cylinder the leading margin of an exposed sheet, and means including elements on a generating line of said surface operative as such line moves in the shorter path between said zone either to hold the leading margin of a sheet on said surface out of engagement with said guide means, for repeated exposure of the sheet, or to eject such margin into engagement with drawing. When the apparatus is operating, the said original is introduced at the correct moment in the above-mentioned place on the rotating cylinder. The original now passes through the long stretch between the radii 8 and 9 in the direction of the arrows in a position essentially corresponding to that of the original I0 illustrated in the drawing. As soon as original No. 30 has been introduced, the next original (No. 29) is put in readiness at 25. During the introduction the duct 12 may be caused to act as a suction device. When the leading end of original No. 30 approaches the radius 9, the apparatus will be automatically switched over to blowing and, when passing radius 9, the leading end of original No. 30 is lifted off the cylinder 1 by the blowing and passes along the screen IS, the blower 20 to the place of discharge 2!.

If desired, the apparatus is now again switched over to suction, and when passing radius 8 the original No. 29 which had already been put in readiness is taken along. Thus the originals Nos. 28, 27 etc. are treated successively and the copies thereof are found in the same order on web 3; in this order they are out at [3 and discharged at [5. If, after the introduction of original 1, the copying is repeated in the same order a number of stacks of copies in the order of the originals, with No. l on top, is obtained at l5.

When thus an edition of several sheets is made,

the operation of the apparatus has to meet high reliability requirements. The apparatus according to the invention is capable of satisfying these.

The invention is not limited to the apparatus according to the drawing. It is, for example, posy sible to operate with sheets of light-sensitive material instead of with a web of such material. In that case, as in British patent specification No. 501,103 an endless conveyor-belt runs around part of the cylinder circumference in order to ensure the contact necessary for the copying (applying apron). This conveyor-belt takes along the cylinder or the cylinder itself is driven. In that case, for example, an automatic sheet supply for light sensitive sheets may act synchronously with the rotation of the cylinder, while for the rest such an apparatus is capable of performing any of the operations already described.

An embodiment of this invention is disclosed.

in connection with further new structures and combinations for automatically exposing originals in succession, in our copending application Serial No. 52,922, filed October 5, 1948.

What we claim is:

1. In a photographic contact printing apparatus, a rotatable light pervious cylinder to contain a light source for exposure of sheet material on the cylinder, air duct means in the light pervious body of the cylinder opening to its outer surface and distributed thereon along a generating line at a limited circumferential part thereof, and an air displacement system to communicate with said duct means including means for applying suction therethrough to hold to said surface the leading margin of a sheet to be exposed thereon at least while said duct means moves through a minor portion of its path of rotation.

2. In a photographic contact printing apparatus, a light pervious exposure cylinder rotatable about a light source therewithin, air duct means in the light pervious body of the cylinder opening to its outer surface and arranged thereon along a generating line at a limited circumferential part thereof, and an air displacement system including an air passageway communicating with said duct means at least as the same turn in a minor part of the path of rotation of said surface for applying either suction or air pressure through the passageway and the duct means to the leading margin of a sheet in said minor part of said path.

3. An apparatus as described in claim 2, said surface being recessed at said duct means so as to present an abutment fixed adjacent thereto for positioning the leading edge of a sheet being applied to the cylinder.

4. In a photographic contact printing apparatus comprising a light pervious exposure cylinder rotatable about a light source therewithin, means respectively for leading an original and light-sensitive sheet material to the outer circumferential surface of the cylinder, means separate from the cylinder for pressing the original and said material closely together and against said surface over a major part of its path of rotation and for moving the pressed materials and said surface together in such part for exposure about the light source, air duct means in the light pervious body of the cylinder opening to said surface and extending thereon along a line substantially parallel to its axis, and an air displacement system including a stationary air passage communicating with said air ducts at least as they move in the remainder of said path for applying either suction or air pressure through the air ducts to the leading margin of an original therein.

5. In a photographic contact printing apparatus comprising a light pervious exposure cylinder rotatable about a light source therewithin for exposure of sheet material entrained over its outer surface, fixed sheet applying and sheet removal zones in closely spaced relation at said surface, means respectively for applying a flexible web to said surface at said applying zone and for removing the web at said removal zone, the web passing about said surface between said zones and moving with it therebetween through an exposing path spanning most of the circumference of said surface, there being a gap at said surface for the ingress and egress of sheets between web portions respectively approaching and leaving said surface, air duct means in the light pervious body of said cylinder opening to said surface and distributed thereon along a generating line at a limited circumferential part thereof, and an air displacement system including an air passageway communicating with said duct means at least as the same move through said gap for applying either suction or air pressure through the duct means to the leading margin of a sheet in said gap.

6. In a photographic contact printing apparatus, a light pervious exposure cylinder rotatable about a light source therewithin to move its outer surface through an exposing path over most of its circumference, from a fixed sheet applying zone to a fixed sheet removal zone, and then through a shorter return path spanning said zones, air duct means in the light pervious body of the cylinder opening to said surface and distributed thereon along a generating line at a limited circumferential part thereof, and an air displacement system including an air passageway communicating with said duct means at least as the same move through said return path and means for applying suction through said passageway and said duct means to the leading margin of a sheet in said return path.

said guide means, the last recited means including air duct means in the body of said cylinder opening to said surface along said generating line and an air displacement system including means for applying either suction or air pressure through said duct means.

THEO PIERRE CHRETIEN BREUERS.

THEODOOR HILLEBRAND LINTHOUT.

REFERENCES CITED The following references are of record in the file of this patent:

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