US 3903541 A
This invention relates to a dispensing apparatus for lithographic developer comprising bar means adapted to extend across a printing plate to be developed, slot means in the bottom of said bar means, means for supplying developer under pressure to said slot means, and means for reciprocating said bar means transversely to the direction of plate travel.
Claims available in
Description (OCR text may contain errors)
NJ. 07871; Robert C. Graham, 10 Pierson Ln., Florham Park, NJ. 07932 July 27, 1971 (Under Rule 47) Appl. No: 166,474
 References Cited UNITED STATES PATENTS 2.677.320 5/1954 Coughlin 95/89 R United States Patent 1191 1111 3,903,541 Von Meister et al. Sept. 2, 1975  APPARATUS FOR PROCESSING PRINTING 2,956,494 10/1960 Tyler et a1 118/410 UX PLATES PRECOATED ON ONE SIDE ONLY 3,066,047 11/1962 Mahoney 118/120 X 3,081,687 3/1963 Takats 95/89 R  Inventors: Frederick W. Von Meister, WlllOW 3,338,149 8/1967 Hemery 95/89 R Ave., Peapack, NJ. 07977; Eugene 3,354,807 11/1967 Homer 95/89 R X J. Gaisser, Jr., 2 Circle Ten, Sparta, 3,593,641 7 1971 Adams et a1 118/120 x Primary Examiner-Richard L. Moses Attorney, Agent, or F irm-James E. Bryan and means for reciprocating said bar means transversely to the direction of plate travel.
ABSTRACT 4 Claims, 3 Drawing Figures DEVELOPER SUPPLY LINE DEVELOPER SUPPLY RECIPROCATOR 38 SHAFT J/VOLLME REGULATOR SPREADER BLADE PHETZTETESEP EH75 3 903541 SHEET 2 U? 3 FIG. 2
8 TRANSPORT ROLLS DEVELOPER PLATE TRAVEL RECIPROCATOR SHAFT E SUPPORT HEAD RAIL INVENTORS FREDERICK W. von MEISTER ENE J. GAISSER, JR.
R ERT C. GRAHAM ATTORNEY PATENTEU 2W5 3.963 541 SEZCET 3 OF 3 DEVELOPER SUPPLY LINE RECIPROCATOR 38 SHAFT SPRING IIII 1 1 INVEN FREDERICK W. von MEI EUGEEE J GAlSSER,J
ROB c. GRAHAM A TORNEY APPARATUS FOR PROCESSING PRINTING PLATES PRECOATED ON ONE SIDE ONLY This invention relates to an apparatus for processing a printing plate precoated on one side only, and more particularly relates to a dispensing apparatus for lithographic developer.
It has long been known in the lithographic industry that a subtractive presensitized offset printing plate may be developed by what is known as the hand developing process. In this process the carrier, which is usually a thin sheet of aluminum, is first coated by the manufacturer with a light-sensitive coating usually containing, among other things, one or more resins, and the plate is then sold in the presensitized condition to the customer.
The customer exposes the printing plate through a stencil to a source of strong light, such as a carbon are for example. The lightsensitive coating when subjected to such a light is converted in such a manner that, after development, the image areas are retained on the plate surface and the non-image areas are removed. After development, for example by rubbing a developing agent into the surface of the plate by means of a sponge, the plate may be fixed and/or washed and, finally. a coating of gum arabic or similar material is applied to the surface of the plate to protect the image free areas thereof. The plate is then ready for the printing press.
More specifically, where this hand developing process is employed to produce a printing plate, the following procedure is generally followed: From a typewritten setup or makeup, equivalent to the material to be printed and provided in any desired manner including typed articles. pictures of various kinds of art work of different sizes, and the like, all assembled onto a suitable cardboard or other support, a master is prepared in the conventional manner. The image of the master is then transferred onto the sensitized printing member, such as is described above, by a suitable exposure means.
The printing member thus prepared is then subjected to a developing operation using the chemistry prescribed by the manufacturer of the printing member. This chemistry" is worked into the exposed coating by hand rubbing, for example with a sponge, until the nonimage areas are subtracted or removed from the carrier leaving an exact replica of the image on the plate carrier. The printing member is then fixed and/or washed and a solution of gum arabic, or a similar solution, is applied to the plate surface, resulting in a printing plate which is ready for the press.
The disadvantages of hand development of offset printing plates are numerous. The process is slow and expensive. Uniformity of pressure in applying the de veloping solution to remove the undesired coating is almost impossible to attain and exposure to the developing solution is uneven. Thus, defective printing often results from an inadequate development or underdevelopment of an area or from applying varying pressure by hand, which may adversely affect the desired printing image. Drying of the developer on certain portions of the plate before it can be rubbed in to remove the undesired coating also may leave a residue on the plate. A further difficulty with the hand method is in the application of the developing solution. It is presently the practice of the craftman to pour a quantity of developer onto a developing sponge or pad and onto the center of the plate, which quantity is supposedly sufficient to process the plate, and the craftman then works his sponge from that reservoir. This procedure may lead to a high degree of contamination of the processing fluids by the removed photosensitive coating as well as a change in the chemistry of the fluid because of evaporation, which will, in turn, either reduce the efficiency of the chemistry, resulting in incomplete removal of the undesired coating in highly critical areas of halftones, or increase its potency resulting in image attack.
The present invention overcomes the difficulties associated with conventional hand developing of a plate coated on one side only by providing a novel dispensing apparatus for lithographic developer. The dispensing apparatus avoids changes in the processing solutions by a unique method of metering the processing fluids in controlled quantities onto the plate surface without damaging the plate surface, rendering it possible to economically use the processing solutions only once, and without smearing or dragging used solutions into fresh solutions or onto adjacent plate areas.
Prior to the present invention, there was no successful way to deposit a minimum amount of fluid automatically onto a printing plate for a one-time use of such fluid so that a machine operation was economical. Attempts were made to process plates by recirculating the fluids through conventional spraying systems onto the surface of the plate and by dipping the plate into tanks of fluids, but it has been characteristic of many such fluids to become prematurely weakened by unavoidable aeration or by contamination of spent material from the non-image areas, resulting in a short period of time in an unusable solution. Further, when only small quantities of fluid are required to process a plate, such as one ounce of fluid per square foot of plate surface, it is essential to hold fluid consumption at this level in order to avoid extra costs.
The problem of metering small quantities of fluid over a large surface area is effectively overcome by the novel dispensing apparatus of the present invention. In the novel apparatus, fluid is pumped under pressure into a manifold, which may have a width of about one inch and a height of about one-half inch. On the bottom of the manifold a plurality of apertures dispense the fluid, under pressure created by a pump, into a second bar which has a width of about one inch and a length corresponding to the width of the machine. The bottom bar contains a slot which may have a width of about 1/16 inch, for example. The bar is made of plastic so that it does not scratch the surface of the plate in contact therewith. The entire assembly is spring-loaded and rests on a backup plate made of hard rubber.
When the processing apparatus is actuated, a pair of nip rolls transport a plate into a developing station and between the backup plate and the dispensing apparatus. The pump pressure forces a quantity of developer into the slot in the dispensing apparatus and, since there is a backup plate facing and in contact with the spring-loaded bar of the dispensing apparatus, the slot in the bar fills with developer prior to the entrance of the plate and causes a slight rising of the entire assembly, by about 0.015 inch. with little or no outflow of the developer. This rise, in turn, allows the plate to enter between the bar and the backup plate without actually contacting the dispensing apparatus.
As the moving plate receives fluid developer from the slot in the bar and carries the developer away, the developer is constantly replaced from the manifold as a result of the pressure of the pump supplying developer from the reservoir. Simultaneously, this continuing feed of developer maintains the dispensing assembly above the surface of the plate to be developed and the inverted menicus created dispenses a minimum coating of developer, regulated by the pressure of the feed pump, uniformly upon the plate.
After passing the developing station, a reciprocating rubber squeegee assures that the developer is adequately rubbed into the surface of the plate. By proper composition of the developer, the action thereof can be made rather rapid so that shortly thereafter it can be squeegeed off and drained away into a waste disposal by a pair of squeegee rolls.
A second application of developer, if required, may be applied in a similar mechanism. A third similar mechanism can be employed to apply a fixing solution, if necessary, for the proper preparation of the plate. This may be combined with a rubbing action of a piece of velour-like material reciprocating transversely to the direction of plate travel at a rate of about 175 strokes per minute. in a stroke of about one-half inch. The plate then enters a washing station and a lacquering station, if required, followed by a second washing or gumming station before exiting from the apparatus as a completed plate ready for the printing press or for further work prior to going to the printing press.
The invention will be further illustrated by reference to the accompanying drawings in which FIG. I is a schematic view of a processing line for processing printing plates precoated on one side only,
FIG. 2 is a perspective view of a portion of the processing line of FIG. 1 showing the developer dispensing apparatus, and
FIG. 3 is a sectional view taken on line 33 of FIG. 2 and looking in the direction of the arrows.
Referring to FIG. I, a planographic printing plate sensitized on one side and imaged by exposure to a desired master is inserted into the processing line at the point of the arrow 2. The inserted plate passes over the trigger mechanism 4 and thus actuates the entire processing line, i.e., the feed rolls as well as all transportsqueegee rolls begin rotating. Simultaneously, pumps connected to the various chemical supply tanks, not shown, begin operating and dispensing chemistry as required. Also the developer dispensing apparatuses or heads as well as the rinse-scrubber head begin reciproeating.
The plate passes through a pair of feed rolls 6, which rolls pass the plate between the first developer dispens ing head 8 and its associated support rail 10, and a controlled amount of developer at a controlled temperature is dispensed from the developer dispensing head 8 onto the plate surface and carried away. This amount can be regulated by adjusting the pressure in the developer supply line by setting a bypass, not shown, and a volume regulator which will be described below in connection with FIG. 3.
Inasmuch as the entire developer dispensing head reciprocates, and since the dispensing head has a spreader blade 12 attached thereto, chemistry is evenly spread over the entire surface of the plate and adequately and completely rubbed into the surface of the plate coating.
The plate then passes through a first set of transportsqueegee rolls 14 which rolls transport the plate into the second developer dispensing assembly 16 having an associated backup plate 18. The construction of the second developer dispensing assembly 16 and its associated backup plate 18 is identical with the construction of the first developer dispensing head 8 and its associated backup plate 10.
The second developer dispensing head reapplies a fresh amount of developer solution in the same manner as the first developer dispensing head 8. With this arrangement, a rapid and thorough development of the plate is obtained inasmuch as the "chemistry" is previously adjusted to process the exposed image within the time allowed by the speed of the plate travel and the distance between each set of rolls.
The plate then reaches a second pair of transportsqueegee rolls 20 which remove all excess developer and, in turn, propel the plate under the rinse-scrubber head 22 which removes residual developer from the plate before it enters the third transport-squeegee roll assembly 24. The latter rolls advance the plate under the gum dispensing tube 26 and into the transportsqueegee rolls 28, which latter move the plate between the air dryer tubes 30 and into the exit rolls 32 which, in turn, propel the developed, gummed and dried planographic printing plate out of the processing line ready to be mounted on a press.
Referring to FIG. 2, a plate 34 is shown as it passes between the feed rolls 6 and under the first developer dispensing head 8. As will be seen from FIG. 2, developer is supplied through the developer line 36 and the dispensing head is reciprocated transversely to the direction of plate travel by means of the reciprocator shaft 38.
The dispensing head is shown in more detail in FIG. 3. The dispensing head includes the bottom bar 40 which abuts against the hard rubber surface 42 of the backup plate 10 when no plate is received between the two. The bottom bar 40 has a slot 44 therein which extends across the length of the bottom bar 40 but not completely to the ends thereof, so that developer pumped into the slot cannot run out of the ends thereof. The developer is supplied to the slot 44 by means of the passage 46 which connects to the reservoir 48 in the manifold 50. The reservoir 48 is connected to the developer supply line 36 by means of a bore in the rod 52. The rod 52 slides freely in the supporting bracket 54, to which the reciprocator shaft 38 is connected by the machine screws 56, and the entire assembly is reciprocated by the shaft 38 connected to a reciprocating apparatus, not shown.
The bar 40, which may be made of plastic, is biased against the surface of the plate 34 by means of the spring 58 and any degree of pressure desired may be obtained by balancing the spring pressure against the pressure of the developer supplied to the slot 44.
The volume of developer supplied to the slot 44 may be regulated by the developer supply volume regulator 60 having a hand wheel 62 thereon. The supply volume regulator is of conventional construction and, accordingly, will not be further described.
The entire processing line is enclosed in a housing, not shown.
The processing line is intended to be used with fresh chemistry at all times, i.e., there is no recirculation. By so doing, all parameters are maintained constant and since, in addition, the temperature of the developer is controlled to within 5F., processing of printing plates is predictable and reproducible.
It will be obvious to those skilled in the art that many modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.
What is claimed is:
l. A dispensing apparatus for lithographic processing fluids, comprising; bar means adapted to extend across a printing plate to be processed, having a single outlet means comprising a slot in that side of said bar means facing said plate to be processed and an inlet means in fluid communication with said outlet means, mounted to move perpendicular to the surface of said plate to be processed and normally biased toward the side of said plate to be processed; means for supplying processing fluid, under pressure sufficient to overcome the biasing of said bar means and move said bar means away from the surface of said plate to be processed; and means for reciprocating said bar means transversely to the direction of travel of said plate to be processed.
2. A dispensing apparatus according to claim 1 including spring means biasing said bar means toward a plate to be developed.
3. A dispensing apparatus according to claim 1 including spreader blade means secured to said bar means.
4. A dispensing apparatus in accordance with claim 1 wherein the bar means is biased toward the plate to be processed by means of a spring.
UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,903,541
DATED September 2, 1975 I INVENTOR(S) Frederick W. von Meister and Eugene J. Gaisser, Ir.
It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below: I
Item the name of. the third inventor, i.e. Robert C.
Graham, 10 Pierson Lane, Ptorham Park, New Jersey 07932 should be deleted.
Signed and Sealed this Arrest:
RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner of Parents and Trademarks UNITED STATES PATENT OFFICE CERTIFICATE OF coRREcrr PATENT NO. I 3,903,541
DATED September 2, 1975 v INVENTOR(S) Frederick W. von Meister and Eugene I. Gaisser, Ir.
It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below: a t
Item the name ofjthe third inventor, i.e. Robert C. Graham, 10 Pierson Lane, Plorham Park, New Iersey 07932 should be deleted.
gigned and gcafied A nest:
RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner nj'larents and Trademarks