Abstract: The durability of negative working lithographic plates is enhanced by post-exposure to a wavelength, or a range of wavelengths, effective to promote further addition polymerization and/or cross-linking reactions. Preferably, the electromagnetic energy used for post-exposure comprises a principal wave length not greater than 300 nanometers.

Abstract: A conveyor conveys first and second plates to an exposure station. First and second laser imagers mounted at the exposure station above the support generate first and second laser beams adapted to sweep over the first and second plates, respectively. A mechanism effects simultaneous relative movement between the first laser imager and the first plate and between the second laser imager and the second plate. A computer system receives source image data corresponding to first and second source images, which correspond to first and second print images to be formed on the first and second plates, respectively. The computer system generates a first set of electrical signals corresponding to the first source image which are provided to the first laser imager, and generates a second set of electrical signals corresponding to the second source image which are provided to the second laser imager.

Abstract: Apparatus for subjecting photosensitive letterpress lithographic plates to a pre-exposure operation and then to a main exposure operation. The apparatus includes a support for supporting a letterpress plate at a pre-exposure station, a pre-exposure system for pre-exposing a plate on the support, an infeed conveyor system for conveying a pre-exposed plate from the pre-exposure station to a main exposure station, a main exposure system at the main exposure station for exposing a pre-exposed plate, and an outfeed conveyor system for conveying a plate away from the main exposure station.

Abstract: This invention relates to a novel photosensitive element comprising: a support having a surface; a photosensitive layer on the surface; and a transparent, protective coating on the photosensitive layer. The photosensitive layer comprises a composition of an ethylenically unsaturated compound and a photo-initiator, and is capable of photo-initiated addition polymerization. The PVA-based protective coating is substantially impermeable to atmospheric oxygen. In accordance with this invention, it has been discovered that photo-speed in a photosensitive element is substantially enhanced if this coating contains a acid, and especially if the coating exhibits an acidic pH, preferably less than about 5.5. The protective coating preferably also contains a second polymer which imparts surface hardness and scratch resistance to the protective coating. The coating may further contain a plasticizer to impart flexibility and inhibit cracking and snow-flaking.

Abstract: A system for generating from unimaged plates a plurality of exposed lithographic plates to be provided to a press for use in printing. The system is for use with a film exposer for exposing a negative which includes an identifying code identifying the negative. An exposing station has a first reader for reading the identifying code and has an exposer for exposing a number of unimaged plates to generate an image thereon from the exposed negative. The number of exposed plates corresponds to the identifying code read by the reader. A bending station has a second reader for reading the identifying code on the exposed plates and has an optical punch bender for bending the exposed plates in accordance with information corresponding to the identifying code.

Abstract: Apparatus for exposing photosensitized plates to light through films. The apparatus has an infeed end, an outfeed end forward of the infeed end, opposite sides, an exposure station forward of the infeed end at which a plate is exposed to light through a film, and a carriage for carrying plates and films in a forward direction from a loading station at the infeed end of the machine to the exposure station. The apparatus includes a support for supporting a stack of plates at one side of the apparatus generally adjacent the infeed end of the apparatus. A conveyor system conveys a plate in side-to-side direction with respect to the apparatus from the one side of the apparatus to the loading station. A transfer mechanism removes a top plate from the stack of plates and transfers it to the conveyor system for conveyance to the loading station.

Abstract: Lithographic plates have an identifying folio and an image thereon. The image corresponds to a print image to be printed on sheet material such as newspaper stock. An image camera optically examines the identifying folios of each of the lithographic plates to ascertain folio information, and optically examines the images of each of the lithographic plates to ascertain image information including registration information and exposure information. A CPU records in an the electronic memory the ascertained folio information of the identifying folio of each lithographic plate and records in the electronic memory the corresponding ascertained image information of the image of each lithographic plate. An operator using a keyboard can access the image information of a particular plate recorded in the electronic memory by reference to the corresponding recorded folio information for the particular plate whereby the folio information and the image information are cross-referenced.

Abstract: Apparatus for bending a lithographic plate having an image thereon, comprising an inspection system for (a) inspecting a plate held on a table at an inspection station, (b) determining the extent to which the plate needs to be adjusted relative to a predetermined reference position, and (c) generating a signal indicative of any such adjustment. A first positioning mechanism responsive to the signal automatically moves the table to position a plate on the table for a bending operation.

Abstract: Method of and apparatus for punching and bending a lithographic plate to match a particular press so that when the plate is subsequently mounted on that particular press, it is oriented to print a properly positioned image on a print surface.

Abstract: Automated apparatus and method for exposing lithographic plates to light through films and masks. The method involves placing a plate, film and mask at an exposure station in superposed relation to one another with the film overlying the plate and the mask overlying the film, exposing the plate to light through the mask and film at the exposure station, raising the mask off the film to a raised position, gripping the film and moving it relative to the plate to expose a portion of the plate therebelow, gripping the exposed portion of the plate, gripping the mask in its raised position, moving the film, plate and mask forwardly while so gripped to a discharge station, and releasing the film, plate and mask at the discharge station.

Abstract: Apparatus for exposing photosensitized plates to light through films, having a window movable up and down at an exposure station adapted to grip a film after an exposure of a plate and to lift the film away from the plate, plates and films being fed in under its raised window from a loading station, films being discharged from the bottom of the raised window to a tray located above the loading system in a position wherein it does not interfere with manual loading of plates and films in the apparatus.

Abstract: A method of automatically inspecting an exposed and bent lithographic plate having an image thereon to determine whether the image is in proper registration relative to the plate. The plate has front, rear, and opposite side edges.

Abstract: A waste water cleaning system for use with apparatus for processing exposed lithographic plates, the processing apparatus receiving wash water for use in the processing. The cleaning system includes a centrifuge for removing contaminants from waste water from the processing apparatus, the centrifuge having an inlet for receiving waste water from the processing apparatus and an outlet for discharging the cleaned water. The cleaning system also includes means for carrying the waste water from the processing apparatus to the inlet. The cleaning system further includes control means for controlling the operation of the processing apparatus and the centrifuge. The control means includes means for starting the centrifuge and means for starting the flow of wash water into the processing apparatus a first predetermined time after the start of the centrifuge.

Abstract: A method of and apparatus for exposing boards which are photosensitive on both sides, for production of printed circuits on both sides, to light through films on both sides in which a lower film, a board, and an upper film in registered position on a light-transmitting platen are pressed down by a window and exposed to light on both sides through the platen and window, the window, gripping the upper film, is raised, the exposed board is removed, another board to be exposed is applied to the lower film on the platen, the window is lowered to apply the upper film to the new board, and the procedure repeated.

Abstract: An apparatus for and method of exposing lithographic plates to light through films in which plates are brought into an exposure station for exposure alternately on first and second platens, each movable from a loading position outside the exposure station to an exposure position.

Abstract: An apparatus for exposing boards which are photosensitive on both sides, for production of printed circuits on both sides, to light through films on both sides in which a lower film, a board, and an upper film in registered position on a light-transmitting platen are pressed down by a window and exposed to light on both sides through the platen and window. A pair of registration pins are adjustably positioned in spaced relation along an edge of the platen and corresponding holes in the boards are used to align the boards and films for exposure. The pins are spaced as widely apart as possible to provide maximum registration between boards of varying sizes and films.

Abstract: Apparatus for exposing lithographic plates to light through a film, e.g. a negative, adapted for exposing one plate to light through a film or a plurality of plates to light through a film, having a first carriage with vacuum grippers for picking up a plate and a negative from each of two side-by-side plate stacks and two side-by-side negative stacks, the carriage being adapted to carry the picked-up plates and negatives to an exposure station and deposit them in registration on a platen at the exposure station for exposure of the plates to light through the negatives and through a window movable up and down at the exposure station, the window having vacuum grooves for raising the negatives, the apparatus further having a second carriage with vacuum grippers for gripping the plates exposed at the exposure station and negatives raised with the window and carrying the exposed plates and the films away from the platen and the window and out of the exposure station.

Abstract: Apparatus for processing lithographic plates after they have been exposed and developed having a system for feeding plates forward one after another in a predetermined path with the exposed and developed face of the plate facing up, a heating system for heating each plate as it travels along said path, a system for blowing air on each plate to cool it, a system for spraying water on and scrubbing the upper face of each plate for washing it, and a system for delivering preservative onto and rubbing it over the upper face of each plate.

Abstract: A method of increasing the strength, abrasion resistance, solvent resistance, and press life of a lithographic image comprising a layer of light-reacted light sensitive material and an outer layer comprising an epoxy resin overlying the light-reacted layer. In the method, the surface of the outer layer is contacted and wetted with an aqueous solution comprising a least about 7% by weight of a boron trifluoride-amine complex. Solvent is evaporated from the solution on the surface to deposit dry boron trifluoride-amine complex on the outer layer and the outer layer is heated in the presence of the complex to cross-link the epoxy resin and form a hard, tough, abrasion-resistant, solvent-resistant and wear-resistant epoxy resin layer at the outside of the image. Further included in the invention are a curing composition adapted for topical application to a lithographic image in carrying out the method of the invention and a planographic printing plate produced thereby.

Abstract: A base plate adapted to be coated with a light-sensitive diazo resin, and a lithographic plate which may be prepared therefrom. The base plate includes a substrate comprising a metal support and having a water-wettable, hydrophilic surface. Over the substrate and in direct contact with the surface is a layer comprising an oleophilic ink-receptive organic resin adapted to receive a light-sensitive coating comprising a diazo resin sensitizer. The oleophilic resin layer is permeable to the sensitizer so that it may penetrate substantially through the resin layer to establish sufficient contiguity between the diazo resin and the substrate so that both the light-sensitive coating and the organic resin layer become anchored to the substrate in the areas of exposure when the light-sensitive coating is exposed to light. Methods of preparing the base plate and lithographic plate are also disclosed.