Defect compensation for discrete image bars
First Claim
1. In an image recorder including an image bar having a plurality of spatially distributed, substantially independently addressable pixel generators for sequentially recording spatial patterns on a recording medium in response to successive data sample sets representing said patterns, said image bar casting a footprint of predetermined size onto said recording medium, the improvement comprisingmeans for storing a description of said image bar, said description distinguishing between non-defective and defective pixel generators of said image bar whenever any of said pixel generators have been found to be defective;
- means for processing each of said sample sets in accordance with said description to insert (i) the data samples that are positioned to address nondefective pixel generators into corresponding positions within one data string and (ii) the data samples that are positioned to address said defective pixel generators into corresponding positions within at least one other data string;
said data sample sets and said data strings being of equal length, with each of said data strings comprising null data elements in all positions other than those into which data samples are inserted;
means for specifically applying said data strings to said image bar, with each of said other data strings being shifted a predetermined amount in a predetermined direction with respect to said image bar prior to being applied thereto, thereby re-positioning the data samples therein to address non-defective pixel generators of said image bar, andmeans coupled to said image bar for equally countershifting its footprint with respect to said recording medium while each of said other data strings are being applied to said image bar, thereby substantially restoring the data samples within said other data sample sets to their original positions with respect to said recording medium,whereby each of said spatial patterns is relatively faithfully recorded as a corresponding pixel pattern on said recording medium, even if said image bar has defective pixel generators.
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Accused Products
Abstract
A discrete image bar having defective pixel generators redundantly addresses all pixel positions within an address space to produce an essentially defect free image. To that end, the footprint of the pixel generators of the image bar is shifted back and forth across an integer number of pixel positions widthwise of the address space as a function of time, and the input data for the image bar is synchronously countershifted in the opposite direction across an equal number of pixel generators, thereby sequentially bringing at least two different pixel generators into imaging alignment with each pixel position, without materially affecting the address space alignment of the input data. All of the defective pixel generators of the image bar are disabled, so the input data for them are shifted onto non-defective pixel generators after a suitable time delay, whereby the image corresponding to this shifted data is superimposed, sequentially in time, on the image corresponding to the unshifted data for the non-defective pixel generators. These partial images are recorded on a suitable recording medium, thereby causing them to incoherently spatially sum with each other to create an essentially defect free image of the spatial pattern represented by the input data.
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Citations
17 Claims
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1. In an image recorder including an image bar having a plurality of spatially distributed, substantially independently addressable pixel generators for sequentially recording spatial patterns on a recording medium in response to successive data sample sets representing said patterns, said image bar casting a footprint of predetermined size onto said recording medium, the improvement comprising
means for storing a description of said image bar, said description distinguishing between non-defective and defective pixel generators of said image bar whenever any of said pixel generators have been found to be defective; -
means for processing each of said sample sets in accordance with said description to insert (i) the data samples that are positioned to address nondefective pixel generators into corresponding positions within one data string and (ii) the data samples that are positioned to address said defective pixel generators into corresponding positions within at least one other data string;
said data sample sets and said data strings being of equal length, with each of said data strings comprising null data elements in all positions other than those into which data samples are inserted;means for specifically applying said data strings to said image bar, with each of said other data strings being shifted a predetermined amount in a predetermined direction with respect to said image bar prior to being applied thereto, thereby re-positioning the data samples therein to address non-defective pixel generators of said image bar, and means coupled to said image bar for equally countershifting its footprint with respect to said recording medium while each of said other data strings are being applied to said image bar, thereby substantially restoring the data samples within said other data sample sets to their original positions with respect to said recording medium, whereby each of said spatial patterns is relatively faithfully recorded as a corresponding pixel pattern on said recording medium, even if said image bar has defective pixel generators. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification