Abstract: In accordance with the present invention, the control over a high- speed non-linear actuator is improved by linearizing the relationship between the actuating impetus and the feedback control signal via a method that employs the separate and concurrent control of the static and dynamic characteristics of the device without resorting to the use of force-feedback or field-strength feedback. The resonant frequency of the plunger of the actuator is manipulated during operation such as to maintain it at a substantially fixed optimal value. The method is particularly advantageous in devices where space is at a premium and force-feedback or field-strength feedback mechanisms are difficult to implement.

Abstract: The present invention is a method to generate alignable orthogonal images from non-orthogonal scans in a double-sided digital-offset-press arrangement by shifting the image data in the multi-channel modulators in a direction and rate that keeps the images orthogonal. The image data is shifted parallel to the cylinder axes and the amount of shift per cylinder rotation equals the distance the multi-channel modulators move relative to their respective cylinders per rotation of the relevant cylinder. This prevents “parallelogram” type distortion in the images and maintains the orthogonality of the original images, thereby allowing the images on the opposing sides of the printing medium to be aligned. The shift can be done continuously or in discrete steps. The invention is also extendable to two-dimensional modulators such as deformable mirror devices (DMD) and liquid crystal light valves (LCLV).

Abstract: A photosensitive printing element is used for preparing flexographic printing plates. The photosensitive printing element comprises (a) a support and especially a flexible support, (b) a photopolymerizable layer comprising an elastomeric composition sensitive to non-infrared actinic radiation, said layer being soluble, swellable or dispersible in a liquid developer prior to exposure to said non-infrared actinic radiation, and (c) at least one layer comprising a radiation-sensitive imaging layer, such as an infrared radiation sensitive thermographic material that provides excellent image density (e.g., greater than 3.0) at least in the electromagnetic region of said non-infrared radiation sensitivity and preferably in both the visible and ultraviolet regions of the electromagnetic spectrum upon exposure to infrared laser radiation and thermal development. Imaging of the imaging layer (e.g.

Abstract: An apparatus for removing slip sheets from printing plates has two concentric cylinders that are mutually rotatable about a common axis. Suction exerted via two elongated slots separates a deformable sheet from a relatively rigid object to which it is adhered. The deformable sheet is drawn into a recess presented by the two aligned slots. The concentric cylinders are then rotated to grip the deformable sheet between opposing edges of the slots.

Abstract: A method and apparatus are provided for the removal of laser ablation byproducts generated in the imaging of laser sensitive media. In accordance with the invention, the byproducts are generated when a laser sensitive media is imaged with a laser. At least two sources of fluid flow are directed toward the imaging area and are oriented such that a substantial component of the bias of one source is anti-parallel with that of the other. These two fluid flow sources are operative to direct the ablation byproducts away from the imaging area, where they are collected by a sink, to which fluid moves. The sink removes the ablation byproducts from the vicinity of the laser sensitive media.

Abstract: A retainer for holding a printing plate to the cylindrical surface of a vacuum drum has a curved surface which conforms to and seals against the cylindrical surface of the drum. The retainer is held in place by pressure differential. An edge portion of a printing plate is received below a lip which extends along the retainer. The retainer is light in weight and therefore does not significantly unbalance the drum even if it is not always in the same position on the drum. The retainer is also inexpensive to manufacture and less likely than prior art clamps to cause damage if it fails.

Abstract: A light valve which can be fabricated as an array of individually addressable micromachined linear mirror reflective light valves is disclosed. Each light valve may comprise a metallized silicon nitride ribbon situated above a micromachined cavity. Incident light is reflected by the ribbons. The reflected beam travels into an optical collecting system. The ribbons may be caused to deform into the micromachined cavities by the application of electrical signals. Only a small area on the ribbons is required to be reflective. The deformation causes light reflected by the deformed ribbon to be substantially collimated. The collimated reflected light can be directed through a slit and focussed on a spot to record a data element on a recording surface. A light valve array according to the invention may be used for various data recording applications including exposing printing plates, printed circuit boards, silicon wafers, masks for making semiconductor devices, optical data storage systems and the like.

Abstract: An exposure system for liquid photopolymer printing plates has a small movable illumination source. The illumination source moves to expose all of a photopolymer object, such as a printing plate being exposed. The area covered by the light source can be adjusted to match the area of the printing plate. The system does not require a large uniform source of illumination. The collimation of the light source is variable. This permits control over the cross sectional profile of exposed features in the photopolymer. Preferably a flat horizontal glass plate supported by air pressure supports the photopolymer being exposed. An optical sensor and a control system are used in preferred embodiments to keep the plate flat by controlling air pressure in an enclosure beneath the plate.

Abstract: A method and apparatus for a fault tolerant recording system using a pair of laser diode arrays is disclosed. Two monolithic laser diode arrays made of individually addressable diodes are used to record parallel tracks on a recording surface. A pair diodes, (one diode from each array) are assigned to each track, but only one diode (the primary diode) is activated. In the case where the primary diode fails, the secondary diode is activated. Digital delays are employed to synchronize the data from the two diode arrays in order to align the written marks on the recording surface.

Abstract: A device can expose both lithographic printing plates and color proofing materials using the same thermal exposure head. The color proofer mode uses four or more donor sheets and transfers a dye onto a receiver sheet. In order to automate the process, the donor sheets are packaged in a box containing the different donor sheets and receiver sheets in the order they are used by the proofer. The proofer picks up the sheets using a vacuum supply and exposes them.

Abstract: In a computer-to-plate system, printing plates are loaded from their shipping container onto a drum, where they are exposed by a laser. As the plates are packed with paper sheets between them, a paper removal system followed by a capacitance probe is used. The capacitance probe detects any paper remaining on the front or back of the plate. The plate is gravity loaded onto the drum and is resting on two contact points identical in position to the contact points of plate punching equipment. The orthogonal edge of the plate is detected electronically, in order to fully register the image to the plate. Magnetic clamps hold the plate to the imaging drum.

Abstract: A loading table for flexographic printing plates is disclosed wherein pneumatic suction is employed to secure the printing plate to the loading table and pneumatic pressure is employed to reduce the friction when conveying the printing plate from the loading table to an imaging cylinder. The loading table comprises a plurality of openings connected to a reversible pump. Pneumatic suction or pressure from the pump is transferred to the printing plate via the openings in the loading table. While immobilized on the loading table with pneumatic suction, the flexographic plates can be prepared for imaging by peeling the protective coating from the active layer. The coupling of the plate to the loading table surface facilitates such preparatory steps without excessive handling of the plate. After preparation, the pneumatic pressure is reversed and a thin layer of air is created underneath the plate reducing the friction and permitting simple transfer of the plate to an imaging cylinder for further processing.

Abstract: The exposure time of high data rate single spot laser scanner can be extended by the use of Time Domain Integration (TDI) mode imaging to expose thermographic materials. Many thermographic materials, such as thermal printing plates, can not be properly exposed in single spot scanners such as internal drum scanners, due to the shortness of the exposure time of a single spot, but can be exposed by the extended exposure time of TDI scanning. The Scophony effect can also be used as a method of TDI.

Abstract: A method for controlling the color density of colorant transferred to a substrate involves creating tiny gap areas in the coverage of the colorant. The method is useful in producing color proofs of halftone images. The gap areas are typically much smaller than a screen dot in a halftone image. The method permits the generation of a proof which has the same sizes of screen dots as will appear in the final printed image while operating in the saturation portion of the transfer function for the colorant being used. Suitable gap areas may be provided by pulsing a laser used to transfer colorant from a donor to a substrate. The method does not require the use of a variable power laser and therefore is more stable than previous proofing methods.

Abstract: A mask for exposing flexographic plates contains, besides the standard binary image, areas shaded with a partially light absorbing layer. This partial light absorbance changes the exposure in certain areas and optimizes exposure separately for each different part of the image. The mask can be a separate film or integral to the plate. The required absorbance can be automatically computed when the mask is being generated. The invention is particularly useful with thermal films, as thermal films do not have to trade off edge sharpness and gray levels.

Abstract: The traditional trade-off between performance and shelf-life of processless thermal printing plates can be eliminated by using reactive chemicals which are mixed during (or just prior to) application to the plate and imaged shortly thereafter. The utility of high power thermal exposure heads combined with the advantages of mixing two reactive chemicals, allows the generation of high performance processless thermal printing plates on-site, effectively eliminating the requirements of shelf-life and robustness. Furthermore, the process of mixing the reactive chemicals is ideally suited for on-press imaging.

Abstract: The holding of metal printing plates on a rotating drum using vacuum is greatly improved by bending at least one edge of the plate with a curvature approximately matching the drum curvature. Plate can be bent back to flat shape after unloading.

Abstract: A microlens for a multiple emitter laser diode consists of narrow slices cut out from molded aspheric lenses. Each slice is mounted in front of one emitter and the slice position is adjusted in the cross-emitter direction to have all emitter images aligned in a straight line, thus compensating for any lack of straightness in the multiple emitter diode.

Abstract: When exposing thermally imageable materials using a multi-channel exposure head, an overlap of at least one channel is used to avoid a visible border at the point where one group of channels, written at the same time, meets a second group of channels. The overlapped area is written twice with identical data.

Abstract: The exposure time of high data rate single spot laser scanner can be extended by the use of Time Domain Integration (TDI) mode imaging to expose thermographic materials. Many thermographic materials, such as thermal printing plates, can not be properly exposed in single spot scanners such as internal drum scanners, due to the shortness of the exposure time of a single spot, but can be exposed by the extended exposure time of TDI scanning. The Scophony effect can also be used as a method of TDI.