US3409363A - Machine for the automatic reproduction of prints using a photosensitive process - Google Patents

Description

Nov. 5, 1968 e. MATTHAES 3,409,363 MACHINE FOR THE AUTOMATIC REPRODUCTION OF PRINTS USING A PHOTOSENSITIVE PROCESS Filed March 9, 1965 2 Sheets-Sheet 1 h h W 22 J GOTTFR/ED MAT THAE$ INVENTOR.

Nov. 5, 1968 G. MATTHAES MACHINE FOR THE AUTOMATIC REPRODUCTION OF PRIN USING A PHOTOSENSITIVE PROCESS Filed March 9, 1965 2 Sheets-Sheet 2 INVENTOR. GOTTFR/ED MATT/MES United States Patent ABSTRACT OF THE DISCLOSURE A machine for automatically reproducing prints using a photosensitive process employing an upright member having radially extending arms which rotate about the upright member as well as move vertically. A plurality of work stations are arranged radially around the upright member and include a coating station and first and second photographing stations where a plate is suspended from one of the arms. At this location the plate is lowered to the coating station to be coated with a photosensitive substance and then lowered into the first and second photographing stations to have both faces printed.

The present invention pertains to the formation of an image on a plain metallic surface and more particularly to the formation of such images for use in producing printed circuit plates.

The image must be resistant to acids in order to ensure the protection of a portion of the metal during the chemical etching producing the desired image.

Several methods for the formation of such images are known, such as silk screen printing, off-set processing and photosensitive printing. The latter method has the advantage of a more clear and precise reproduction; however, photosensitive printing has previously been performed by hand, and involves the following operations:

Cleaning of the metallic surface;

Applying a photosensitive coating on the cleaned lic surface;

Drying the photosensitive coating;

Sensitizing the photosensitive coating my means of a photographic negative and ultraviolet light;

Developing the unsensitized portion of the coating;

"- Coloring the coating for greater visibility; and

Water washing and drying.

Although the precision obtained by photosensitive printing is great, it has not been utilized to any great extent beo ause of the expenditure of workmanship necessary to perform the aforesaid operations.

Attempts have been made to construct an automatic machine-capable of fulfilling the above operations on a single transportation line through individual working stations; however, these machines have not enjoyed any favorable success due to their systems of transportation, and their inability to obtain the formation of the image for precise reproduction within the restricted tolerances, which is the advantage of photosensitive printing.

Accordingly, it is an object of the present invention to construct a machine for automatically reproducing prints using a photosensitive process by utilizing a roundabout structure.

Another object of the present invention is to construct a machine for automatically reproducing prints using a photosensitive process in the form. of a roundabout having rigid, radially disposed supporting arms, each one of which supports a suspending device to receive the plates to be printed.

One important feature of the present invention is that the suspending device, in cooperation with guide means metal- 'ice on a photographic chamber, ensurses the precise position if the plates to be printed within the photographic cham- The suspending device further serves to ease loading and unloading operations, which can be performed by an operator standing beyond the circle defined by the radially disposed arms of the roundabout.

Another important feature of the present invention is the provision of means for the regulation and control of the position of glass plates, on which photographic negatives are fixed, to ensure the coincidence of the position of the photographic negatives with the image desired on the plate to be printed.

Another feature of the present invention is the provision of apparatus for applying a photosensitive coating on the plate to be printed, so as to obtain a photosensitivepoating of'thin and uniform thickness which is required for good quality reproduction.

Other objects and advanages of the present invention will become apparent from the following description of a preferred embodiment of the present invention as shown in the drawings in which:

FIG.'1 is a top view of a machine according to the present invention;

FIG. 2 is a side view of parts of the machine of FIG. 1;

FIG. 3 is a side view of a suspending device for use in the present invention and i FIG. 4 is a schematic view of apparatus for ensuring the exact positioning of the plate to be printed.

The present invention is constructed in the form of a roundabout with, for instance, eight radial arms B which rotate around a central upright C. These arms may be lowered to vessels situated underneath the arms. Working stations are arranged beneath the arms radially around central upright C. The number of treatment vessels may be greater than, less'than or equal to the number of radial arms B. In FIG. 1 there are shown the following stations of treatment:

1unloading the printed plates 2-loading the plates to be printed 3cleaning the plates to be printed 4coating the plate with photosensitive substance 5--drying by infrared rays 6-cooling 7-first photocamera 8--second photocamera 9-developing the plates 10-coloring the plates 11-washing the plates 12drying the plates.

, As pointed out above, an important feature of the present invention is the device for suspending the plates, the purpose of which is to precisely dispose the plates within the photographic cameras in order to ensure the exact positioning of the plates to be printed with respect to the glass plates bearing the negatives.

The suspending device is illustrated in FIG. 3, and comprises a supporting plate 13 suspended from the radial arm B by means of two lateral springs 14-14 and a central pivot 15 engaged in 16. The position of supporting plate 13 is adjustable vertically by means of a screw 17 and horizontally by means of a screw 18.

Further, the suspending device cooperates with photographic cameras 7 and 8, to exactly position the plates by means of two operating surfaces 19-19 which rest on two prisms 2040 on the cameras. Springs 14-14 together with pivot 15 allow supporting plate 13 to be set in an exact horizontal position during while resting of surface 19-19', on prisms 20-20.

The plates to be printed are suspended on supporting plates 13 by means of a strip 21, which is provided with hooks 22 for suspending plates L to be printed. Strip 21 is introduced into and drawn back laterally on supporting plate 13 so that the loading and unloading of the plates to be printed may be performed by the operator while remaining outside the circle formed by radially disposed arms B of the roundabout.

. A thin, uniform coat of photosensitive substance or photoresist is applied to plate L at the station 4 which includes a vessel 33, into which the plate to be printed is in. troduced as shown in FIG. 2. After this introduction, an electrically driven pump 35 fills the vessel with photoresist until the plate to be printed is submerged. At this time, the pump 35 is stopped and a discharge valve 36 is opened to allow the photoresist to flow into a tank 38 lodged beneath the vessel. The viscosity of the coating substance and its fast discharge into tank 38 determine the desired thickness of the coating on the plate to be printed, and this thickness is controllable at will.

The photoresist must be absolutely free from dust and solid particles since their presence wouldcause imperfections in the print, and the machine of the present invention is therefore equipped with a photosensitive coating station wherein the plates are dipped into a vessel which is then filled with photoresist. After the photoresist has reached a predetermined level, a variable valve is opened, and the resist exits slowly into a tank below the vessel. The surface tension of the photoresist will leave a thin film on the plate and droplets will be drawn away.

Design of the valve and shape of the vessel may be chosen so that the exit speed of the liquid is such that the layer of the resist is equal at any level of the plate.

The resist should exit quickly at the beginning and slower when the level of the resist has reached the lower part of the plate where a thicker layer has been formed by the retreating resist on the plate.

While flowing to the main tank the resist passes a filter where all impurities are eliminated, and a perfect print without pinholes can be achieved.

After the plates have left the coating station, the pump or similar devices transport the resist back to the container to coat the next plate. An exact control system and a large overflow insure accurate maintenance of the resist level.

Dipcoating of the plates applies a layer of resist on both sides so that the plates can be printed in two successive photoprinting stations.

Within the photographic cameras 7 and 8, one of which serves to print one face of the plate L and the other one to print the opposite face of the same plate, glass plates 34 bearing negatives 24 to be reproduced onto plates L are contained as shown in FIG. 4.

Within each of cameras 7 and 8 apparatus is provided to ensure'the precise positioning of the plate L to be printed with respect to glass plate 31 bearing the nega tive 24. This apparatus is illustrated in FIG. 4 and comprises a frame 26, whereon a flexible sheet 23 is fixed, made, for instance, of rubber. Frame 26 also has pivots or pins 27 attached thereto, and rubber sheet 23 has a mouth 32 communicating with a vacuum pump 33 and a mouth communicating with a contact vacuum meter 29. The plate to be printed is indicated at 30 in FIG. 4. An electric switch 25 is connected in series between a source of electricity 40 and vacuum pump 33, and source 40 is also connected in series between actinic lamps 28 and vacuum meter 29.

The operation of the apparatus is such that after plate 30 has been lowered into one of the cameras 7 or 8, frame 26 and glass plate 31 are displaced in the directions indicated by the arrows by any conventional means, not shown. Pin 27 will pass through holes in-the plates 30 and 31 in order to precisely position the plates With respect to each other. When pins 27 have passed through the holes of both plates, electric switch 25 closes which starts vacuum pump 33. Due to the vacuum within the photographic chamber formed by frame 26, sheet 23 and plate 31, plate 30 is pressed against glass plate 31.

For precision printing and reproducing the position of plate 30 with respect to negative 24 on glass plate 31, it is necessary that pins 27, provided for reference purposes, allow plate 30 liberty of movement. To this end, pins 27 close electric switch 25 to start vacuum pump 33 only when both plates have assumed their exact position, in other words, when the pins have traversed both plates.

It is also important that lamps 28 do not light the plates before they are pressed against one another in good order. To this end, a contact vacuum meter 29 is provided, which closes a switch to permit lighting of lamps 28 only when the vacuum within the photographic chamber'is sufficient to ensure the indispensable contacting o-fboth plates.

The other working stations of the roundabout are known and do not require particular description.

Since the present invention is subject to many variations, modifications and changes in detail, it is intended that all matter contained in the specification or shown on the drawings shall be interpreted as illustrative and not in a limiting sense.

What I claim is:

1. In a machine for the automatic reproduction of prints using a photosensitive process and constructed in the form of a roundabout, the combination comprising an upright member, a plurality of arms radially disposed from said upright member, means connecting said plurality of arms with said upright member so that said arms are rotatable about said upright member and vertically movable, a plurality of working stations located beneath said arms and radially around said upright member, and a plurality of suspending means each attached to one of said plurality of arms and adapted to support a plate to be printed and each of said plurality of suspending means including a supporting plate, horizontal adjusting means connected with said supporting plate, and vertical adjusting means including a central pivot connected with said supporting plate.

2. The invention as recited in claim 1 wherein each of said plurality of suspending means includes a strip attached to said supporting plate having hooks suspended therefrom to hold the plate to be printed.

3. The invention as recited in claim 1 wherein one of said plurality of working stations is for coating the plates to be printed with a photosensitive substance and includes a vessel, a tank disposed beneath said vessel, a pump for transferring the photosensitive substance from said tank to said vessel and valve means for draining the photosensitive substance into said tank from said vessel Whereby a plate to be printed may be coated by lowering its associated arm and suspending means to dip the plate into the vessel and then withdrawing the plate.

4. The invention as recited in claim 1 wherein said plurality of working stations includes a first photographic means for printing'one face of the plate to be printed and a second photographic means for printing another face of the plate to be printed.

5. The invention as recited in claim 1 wherein said plurality of working stations includes photographic means having a glass plate with reference holes therein adapted to have a negative aflixed thereto, a frame with reference pins thereon, and a flexible material attached to said frame whereby the insertion of the reference pins of said frame through reference holes in the plate to be printed and the reference holes in said glass plate assure the exact positioning of the plate to be printed with respect to said glass plate.

6. The invention as recited in claim 5 wherein said photographic means includes a vacuum pump and said flexible material has a mouth connected to said vacuum pump whereby said pump is energized after said reference pins have been inserted through the reference holes 5 6 in said glass plate to secure the position of the plate to References Cited be printed.

7. The invention as recited in claim 6 wherein said UNITED SFFATES PATENTS photographic means includes lighting means, vacuum 3,319,556 5/1967 Flore 9573 sensing means connected with said flexible material and 5 FOREIGN PATENTS means connecting said lighting means With said vacuum sensing means whereby said lighting means is energized 12118 4/1933 Austraha' after said vacuum sensing means senses a suflicient vacu- NORTON ANSHER Primary Emmi-"en um to assure that the plate be printed is firmly pressed against the glass plate. R. A. WINTERCORN, Assistant Examiner.

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