CA1215570A

CA1215570A - Exposure device

Info

Publication number: CA1215570A
Application number: CA000441073A
Authority: CA
Inventors: Klaus-Peter Schoen; Klaus Schmitt
Original assignee: Hoechst AG
Current assignee: Hoechst AG
Priority date: 1982-11-22
Filing date: 1983-11-14
Publication date: 1986-12-23
Also published as: EP0109634B1; EP0109634A1; JPS59102238A; AU561850B2; DE3369008D1; DE3243144A1; AU2153983A

Abstract

Abstract of the Disclosure Disclosed is an exposure device which is mounted on a base and in-cludes two exposure lamp arrangements with shutters, as well as a movable mounting support and a stationary mounting support. The movable mounting support is adapted for being displaced between side walls by means of two compressed air cylinders. Positioning elements, which are swivelled upward, have end faces which contact stop faces at the back of a frame of the movable mounting support, when the positioning elements adopt a horizontal position.
A motor is provided for driving drive rollers. Positioning pins which are engaged by springs are extended by the action of compressed air cylinders, in order to adjust masters provided with register perforations, on glass plates of the frames and to accommodate a plate which is to be exposed. A vacuum pump is connected with suction means, which are arranged in the frames. Thus the present invention provides an exposure device which renders it possible to obtain perfect exposure of two photosensitively coated sides of a vertically arranged plate, while preventing air pockets from forming between the two sides of the plate and the masters pressed against them, and which allows uncom-plicated changing of masters.

Description

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The presen-t invention relates to an exposure device for plates carrying photosensitive coatings. The exposure device comprises frame elements which can be separated from each other and moved into contact with each other and are vertically mounted on a base. Between the -frame elements, the plate which is to be exposed and at least one master are arranged and pressed to-gether during the exposure process while, at the same time, a vacuum is pulled. The exposure device further comprises at least one exposure lamp arrangement.
German li-tility Model No. 1,940,812 discloses vacuum printing devices, for example, vacuum printing frames, for exposing photosensitive plates~ films or the like, which are used in the production of relief printing forms. A
vacuum printing device of that kind has a mounting plate provided with two separate aperture systems in the upper surface thereof. One of these systems is connected with a vacuum source and the other with an air-inlet controlling valve. During exposure, the photosensitive plate and a master lying on top are held in contact with the aperture systems by means of a vacuum cover film and are thus hermetically sealed against the surrounding atmosphere. The photopolymerizable plate and a transparent master lying on top, for example~
a photographic negative, a positive or a matrix, are mounted on the flat vacuum printing frame, comprising a supporting frame and the mounting plate fastened in the frame. The mounting plate is supported either in a horizon-tal or in a vertical position. The light source used for exposure emits light having a high ultraviolet fraction, such as, for example, an arc lamp.
The vacuum printing device is designed such that air can only enter into one of the two aperture systems through the air-inlet controlling valve and escapes through the other system towards the vacuum source. As a result, a gentle stream of air is produced between the surface of the unexposed plate and the S~O

matte surface of the master held in contact therewlth, so that the photo-sensitive plate is supplied with the oxygen required for reducing the sensitiv-ity of its upper layer.
In the above-described device, simultaneous exposure of both sides of the photosensitive plate is impossible and is not intended, since the plate carries a photosensitive coating on one side only and there is, only one light source for exposure.
In German Auslegeschrift No. 1,154,351 a copying device is described, which includes an evacuatable housing made of a flexible material and accommodating an original which is to be copied and a photosensitive element in superposed arrangement. The housing is open at one end and is tightly sealed by a transparent plate resting on a gasket which runs around its upper edge. A screen and a transparent air bag of an elastic air-tight material are arranged above the photosensitive element. When the copying device is evacuat-ed, the air bag is extended by the air contained therein and is forced against the underside of the transparent plate and against the screen, thus exerting pressure upon the screen and the photosensitive element. The air which is present between the original and the photosensitive element is pressed outwards, so that creases do not form when the photosensitive element contacts the original. As soon as the evacuation process is completed, exposure is carried out by means of a commercial light source. Just as in the case of the afore-described prior-art device, this copying device only allows exposure of one side of the photosensitive element.
For the production of photoresist images according to United States Patent No. 3,547,730, a support plate is coated with a photoresist material on both sides thereof and is then introduced into an exposure device, which comprises two rectangular frames arranged opposite to each other, transparent ~S51~

pressure plates -to which image-bearing transparencies are attached and radiation sources, for example, arcs. One of the frames is equipped wi-th pins which engage in holes in the opposite frame, in order to obtain an exact adjustment of the transparencies and the coated support plate. At the four corners of the Erames, four springs are provided, which surround pull rods and keep the frames at a dis-tance from each other. Solenoids actuate the pu]l rods against spring pressure, thus causing the frames to contact each other -tightly for the exposure process. During exposure, the transparencies are forced against the photosensitive resist material by mechanical pressure exerted by -the pressure plates, which are pressed together by means of the solenoids. Evacuation of the exposure device is not provided for and, consequently, it may be possible that air pockets, which impair the image quality, are formed between the individual transparency and the photoresist layer.
The present invention provides an exposure device which renders possible a perfect exposure of the two photosensitively coated sides of a vertically arranged plate, while preventing air pockets from forming between the two sides of the plate and the masters pressed against them and which allows uncomplicated changing of masters.
According to the invention, there is provided an exposure device for plates carrying photosensi-tive coa-tings, comprising frame elements which can be separated from each other and moved into contact with each other and are vertically mounted on a base and between which a plate which is to be exposed and at leas-t one master are arranged and pressed together during the exposure ~SS~7~

process while, at the same time, a vacuum is applied, and further comprising at least one exposure lamp arrangement, wherein one of the frame elements is designed as a stationary mounting support and the other frame element comprises a mounting support which is movable in relation to the stationary mounting support, wherein exposure lamp arrangements are disposed on either side of and at a distance from the pushed-together mounting supports, which are connected with a vacuum pump, wherein a motor and pairs of sprockets and gear wheels which are, in each case, mounted on a common shaf-t, are arranged on a lower crossbar of the stationary mounting support on the side facing an adjacent one of the exposure lamp arrangemen-ts and wherein the motor drives the gear wheels by means oE an endless driving chain which is guided over the sprockets.
Each mounting support comprises a planar glass plate in a frame and each frame has suction means which are spaced around its circumference and are connected with the vacuum pump.
The movable mounting support is appropriately displaced on guide means and two compressed-air cylinders are connected with the frame of the movable mounting support and with stationary side walls, between which the movable mounting support can be moved forward and backward.
The invention offers the advantages that handling o:E the masters is facili-tated, imperfections on the exposed plate surfaces are almost entirely precluded, the masters and the plate which is to be exposed on both sides are adjusted to an exact position and the masters can quickly be exchanged.
Below, -the invention is explained in de-tail with ~::., - 4 -5'7~

reference -to an embodiment of the exposure clevice shown in -the accompanying clrawings.
Figure 1 is a diagrammatic -total view in section of the exposure device according to the invention, Figure 2 is a diagrammatic sectional view oE mounting supports of the exposure device acco:rding -to Figure 1, which are separated from each other, Figure 3 is a sectional view of the mounting supports according to Figure 2, which are brought -together, so as to form a gap between them, Figure 4 is a perspective view showing the back of the movable mounting support which has been moved forward in the direction of the stationary mounting support, and Figure 5 is a perspective view showing the back of the stationary mounting support.

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The diagrammatic sectiona] view of Figure 1 shows an exposure device 1 which includes a base 29, a left-halld and a right-hancl exposure lamp arrange-ment 5 and 5', a movable mounting support 2 and a stationary mounting sup-port 11. The exposure lamp arrangements 5 and 5' are stationarily arranged at the ends of the base plate of the base 29. Each exposure lamp arrangement is e~uipped with a shutter 28 and 28l and a lamp emitting light in a spectral region which is adapted to the photosensitive coating on a plate 12 which is to be exposed.
The movable mounting support 2 is carried by side walls 15 and 15' and on the inside of each side wall two guides for rails 3 are attached, as can be seen from the perspective view of Figure 4, so that the mounting sup-port 2 can be moved forward and backward. For displacing the mounting support 2, two compressed-air cylinders 4 and 4' are provided, which are connected with the stationary side walls 15 and 15l and also with the frame 24 of the mounting support 2. When the compressed-air cylinders 4 and ~' are actuated, tl1e movable mounting support 2 is pushed forward in the direction of the stationary mounting support 11 or pulled back again, in a direction away from the stationary mounting support.
Each of the mounting supports 2 and ll has a planar glass plate 23 and 23l in a frame 24 and 24' and is connected with a vacuum pump 22. Around the circumference of each frame 24 and 24' suction devices 7, 7l, 7l- ... are arranged, which are linked up with the vacuum pump 22 via common vacuum lines 31 and 31' (Figures 1 and 4).
For reasons of clarity, the vacuum lines are not shown in Figure 5.
The guides for rails 3 on the inside of each side wall 15 and 15' are arranged above and below the respective compressed-air cylinder ~ and 4'.
Figure l depicts the position in which the two mounting supports 2 S'7~
and 11, have been pushed together and a plate which is to be exposed on both sides, for example, a printing plate or a circuit board 12, is in contact with masters 9 and 9'.
For adjusting and positioning the masters 9 and 9', the stationary mounting support 11 is equipped with positioning pins 6, 6', 6" .... which are passed through the frame 24' of the stationary mounting support 11 and are connected with compressed-air cylinders 14, 14', 14" .. The positioning pins 6, 6', 6" , ... are disposed close to the lower edge of the upper cross-bar of the frame 24' of the mounting support 11 and the compressed-air cylinders 14, 14', 14" , ... are arranged on a level with the positioning pins, at the back of the stationary mounting support 11~ i.e. on the side facing the exposure lamp arrangement 5'. The positioning pins 6, 6', 6" , ... are engaged by springs 19, 19', 19" , ..., for example, compression springs, which push the positioning pins back when the compressed-air cylinders 14, 14', 14'', ... are in the pressureless sta-te, so that the pointed ends of the positioning pins do not extend beyond the glass plate 23' of the stationary mounting support 11. Instead of compression springs, it is also possible to use tension springs which retract the positioning pins. The movable mounting support 2 is provided with adjusting pins 10 and 10' which engage in corres-ponding adjusting holes 18 and 18' in the stationary mounting support 11, and adjust the two mounting supports with respect to each other before they are moved into contact with each other by the compressed-air cylinders 4 and 4'.
As can be seen from Figure 5, a motor 16 and pairs of sprockets 30, 30', 30" , ... and gear wheels 20, 20', 20" , ... which are, in each case, mounted on a common shaft, are arranged on the lower crossbar of the station-ary mounting support 11 on the side facing the exposure lamp arrangement 5'.
The motor 16 drives an endless driving chain 17 which is guided over the -~ 6 --~L2~S~

sprockets 30, 30', 30" , ... The gear wheels 20, 20', 20" , ... mate with further gear wheels 21, 21', 21" , ... mowlted on shafts which pass through the frame 24' of -the mounting support 11. At the front of the mounting support 11, these shafts carry drive rollers 8, 8', 8" , ... which serve to transport the plate 12 which is to be exposed into the loading gap d formed between the two mounting supports in the loading position of the exposure device 1, as shown in Figure 3.
A retractable sensor 13 is arranged on the frame 24' of the stationary mounting support 11 on the side facing the plate 12. Upon actuation by the plate 12, the sensor disconnects a coupling, which is not shown, between the motor 16 and the sprockets 30, 30', 30" , ... or the driving chain 17, respec-tively, in order to stop the drive rollers 8, 8', 8" , ... and thus arrest and position the plate 12 between the mounting supports 2 and 11.
Two swivelling positioning elements 25 and 25', having the shape of latches, are pivotally mounted on the movable mounting support 2. The end faces 26 and 26' of the positioning elements 25 and 25' act as stops and are contacted by stop faces 27 and 27' on the frame 24 of *he movable mounting support 2~ when the exposure device 1 is in the loading position (Figure 3), in which a plate 12 is inserted into the loading gap d. In the loading posi-tion, the positioning elements 25 and 25' extend horizontally, whereas they are swivelled upward in the inserting position for the masters. In order to position the two mounting supports for the supply of plates, it is also possible to use pressure cylinders, the piston rods of which act as stops.
In the text which follows, the opera*ion of the exposure device 1 is explained in detail.
Figure 2 is a diagrammatic view showing the two mountlng supports i5~3

2 and ll in the inserting position for the masters 9 and 9'. The movable mounting support 2 is displaced to -the extreme left-hand position by the two compressed-air cylinders ~ and ~'. The two masters 9 and 9', which are separated from each other by paper inserts, are simultaneously pushed onto the positioning pins 6, 6', 6" , ... of the stationary mounting support 11 and, for this purpose, the masters 9 and 9' are provided with suitable register perforations for the positioning pins. In this position, the positioning elements 25 and 25' are swivelled upward. Immediately before the two mounting supports 2 and 11 are pressed together, they are adjusted with respect to each other by the adjusting pins 10 and 10', which are attached to the movable mounting support 2 and engage in the corresponding holes 18 and 18' of the stationary mounting support 11.
Then the compressed-air cylinders 4 and 4' are actuated in order to move the mounting support 2 in the direction of the stationary mounting support 11 and the two supports are pressed together. As a result, the air which is entrapped between -the frames 24 and 24' escapes and the masters lie flat on the glass plates 23 and 23'. By means of the suction devices 7, 7', 7'', the masters 9 and 9' are then sucked to the glass plates 23 and 23' of the mounting supports. The positioning elements 25 and 25' are swivelled to a horizontal position. The mounting support 2 is then retracted from the station-ary mounting support 11 by means of the compressed-air cylinders 4 and 4', - to such an extent that the so-called loading gap d, which has a width of about 6 to 8 mm, is formed. In this position of the two mounting supports 2 and 11, which is diagrammaticlly shown in Figure 3, the paper inserts are removed.
The plate 12 which is to be exposed is then conveyed sideways, into the gap d, by the drive rollers 8, 8', 8" , ... The sensor 13, for example, a light barrier operating by reflection or a stop switch, disconnects 1~55~7~

the motor coupling, as mentioned above, thus stopping the drive rollers 8, 8', 8~, ... and terminating the transport of the plate 12. The plate 12 which has register perforations in its upper part is accommodated and adjusted by the positioning pins 6, 6', 6" , ... which are extended by the action of the compressed-air cylinders 14, 14', 14" , ...
The exposure device 1 is now in its exposing position, as shown in Figure 1, with the masters 9 and 9' being in contact with the two sides of the plate 12 which is to be exposed. The plate is exposed by briefly opening the shutters 28 and 28' of the exposure lamp arrangements 5 and 5'.
After exposure, the mounting support 2 returns to the loading position and the positioning pins 6, 6', 6" , ... as well as the sensor 13 are retracted into the frame 24' of the mounting support 11. The plate 12 which is now exposed on both sides is discharged from the exposure device 1 by the drive rollers 8, 8', 8" , ... and the device is then ready for exposure of a fresh plate 12.
If the next plate 12 is to be exposed in contact with the same masters 9 and 9', the latter remain adjusted in their positions by the vacuum applied to the devices 7, 7', 7" , ..., during the following loading operation.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An exposure device for plates carrying photosensitive coatings, comprising frame elements which can be separated from each other and moved into contact with each other and are vertically mounted on a base and between which a plate which is to be exposed and at least one master are arranged and pressed together during the exposure process while, at the same time, a vacuum is applied, and further comprising at least one exposure lamp arrangement, wherein one of the frame elements is designed as a stationary mounting support and the other frame element comprises a mounting support which is movable in relation to the stationary mounting support, wherein exposure lamp arrangements are disposed on either side of and at a distance from the pushed-together mounting supports, which are connected with a vacuum pump, wherein a motor and pairs of sprockets and gear wheels which are, in each case, mounted on a common shaft, are arranged on a lower crossbar of the stationary mounting support on the side facing an adjacent one of the exposure lamp arrangements and wherein the motor drives the gear wheels by means of an endless driving chain which is guided over the sprockets.

2. An exposure device as claimed in claim 1, wherein each of the mounting supports comprises a planar glass plate in a frame and each frame has suction means which are spaced around its circumference and are connected with the vacuum pump.

3. An exposure device as claimed in claim 1, wherein the movable mounting support is displaced on guide means and two compressed air cylinders are connected with the frame of the movable mounting support and with stationary side walls between which the movable mounting support can be moved forward and backward.

4. An exposure device as claimed in claim 3, wherein a guide means is arranged above and below each compressed air cylinder on the inside of the side walls.

5. An exposure device as claimed in claim 1, wherein the stationary mounting support is provided with positioning pins for positioning the masters and accommodating the plate and the positioning pins are extended by means of compressed air cylinders.

6. An exposure device as claimed in claim 5, wherein the positioning pins are passed through the stationary mounting support close to a lower edge of an upper crossbeam thereof, the compressed air cylinders are arranged on a level with the positioning pins on the side facing an adjacent one of the exposure lamp arrangements and the positioning pins are engaged by tension springs, which retract the positioning pins when the compressed air cylinders are in the pressureless state.

7. An exposure device as claimed in claim 1, 2 or 3, wherein adjusting pins are present on the movable mounting support, which engage in corresponding adjusting holes in the stationary mounting support before the mounting supports are pressed together and thus adjust the mounting supports to an exact position with respect to each other.

8. An exposure device as claimed in claim 1, wherein the gear wheels, driven by the motor, are mating with further gear wheels mounted on shafts which pass through the mounting support and carry drive rollers on the other side of the mounting support, for transporting a plate into an open loading gap between the two mounting supports.

9. An exposure device as claimed in claim 8, wherein a retractable sensor is arranged on the frame of the stationary support on the side facing the plate, which sensor disconnects a coupling between the motor and the driving chain when it is actuated by the plate and thus stops the rotation of the drive rollers.

10. An exposure device as claimed in claim 1, wherein elements are pivotally mounted on the movable mounting support, the end faces of which act as stops which are contacted by stop faces on the stationary frame, when the exposure device is in a loading position, in which the plate is inserted into a loading gap and the elements are in a horizontal position.