Controller for spark discharge imaging
OwnerJohn F. Kline, Frank G. Pensavecchia +2inventors
InventorsJohn F. Kline, Frank G. Pensavecchia, Stephen M. LaPonsey, Richard A. Williams
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Abstract
An apparatus and method for controlling discharge devices used to image a planographic printing plate are disclosed. Imaging information is stored in a first memory while discharge correction data is stored in a second memory. The correction data is used to vary the intervals between imaging discharges to compensate for error between the sensed position of the printing plate with respect to a writing head and the actual position. Printing artifacts are visually minimized by staggering the imaging devices used to produce separation plates.
Claims25
An apparatus for controlling discharges which are used to form an image on a printing surface, said printing surface being mounted on a rotatable cylinder, said apparatus comprising:
- sensing means, coupled to the cylinder, for generating a signal indicative of the angular position of the cylinder;
- discharge means for selectively producing image spots on the printing surface;
- means for providing relative motion between the cylinder and the discharge means to effect a scan of the printing surface by the discharge means;
- means, coupled to the discharge means, for storing image information, representing the image to be formed on the printing surface, and offset information;
- and
- controlling means, coupled to the sensing means, the discharge means and the storing means, for enabling the storing means to transmit image information to the discharge means, to thereby generate discharges that produce an array of image spots corresponding to the image information on selected points of the printing surface, said controlling means including means for varying, in response to the offset information, the intervals between discharges to different physical locations on said printing surface.
An apparatus for imaging on a press including a plate cylinder and a lithographic plate having a printing surface, said apparatus comprising:
- mounting means for mounting said plate on said cylinder;
- discharge means for effecting discharges between an imaging device communicated with said printing surface and selected points thereon;
- means for providing relative motion between the cylinder and the discharge means to effect a scan of the printing surface by the discharge means;
- and
- controlling means responsive to image information specifying the locations on the cylinder at which discharges are to occur, position information specifying the location of the discharge means relative to the cylinder, and correction data specifying offsets to the position data, the controlling means being operatively coupled to the discharge means such that the discharges occur in response to the image data at selected positions on the printing surface as specified by the offset position data, thereby directly producing on the lithographic plate an array of image spots suitable for reproduction that corresponds to the image represented by the image information.
An imaging and printing system including a cylinder and a lithographic plate having a printing surface, said system comprising:
- sensing means, coupled to the cylinder, for generating position information indicative of the angular position of the cylinder;
- discharge means for producing an array of image spots on the printing surface, said discharge means being responsive to a discharge control signal;
- a computer for storing image data specifying locations on the cylinder at which image spots are to be placed and position-correction data specifying offsets to the position data;
- controlling means, coupled to the computer, the sensing means and the discharge means, for receiving image and position-correction data from said computer and position information from the sensing means, and responsively generating said control signal.
A method of imaging on a press including a plate cylinder and a lithographic plate having a printing surface, said method comprising the steps of:
- mounting said plate on said cylinder;
- receiving positron information indicating the angular position of said cylinder;
- storing image information specifying locations on the cylinder at which image spots are to be placed and correction data specifying offsets to the position data;
- exposing the printing surface at selected points to discharges from an imaging device to produce image spots at these points;
- moving the imaging device and the print cylinder relatively to effect a scan of the printing surface by the imaging device;
- and
- controlling the discharge in accordance with said image, correction and position information so that they occur at selected positions on the printing surface, thereby directly producing on the lithographic plate an array of image spots suitable for reproduction that corresponds to the image represented by the image information.
Dependencies are inferred from the claim text.