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US 4,065,773 AGranted
Method and apparatus for generating gray tones in an ink jet printer
AssigneeTeletype Corporation
InventorJames M. Berry
Life of this patent
Estimating the term…
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AssigneeTeletype Corporation
InventorJames M. Berry
Estimating the term…
The illustrated printer effectively divides the surface of a paper into a large number of small areas termed dot locations each of which may or may not receive one or more ink drops depending upon the tonal level to be printed. Fifteen tonal shades are utilized with the tonal scale evenly divided by averaging the number of drops over a given number of dot locations to effectively generate fractional drop intensities. Selected ink drops generated by an ink jet are charged as determined by an incoming signal and the charged droplets directed at selected dot locations on the paper. The charge duration is not related to the frequency of the ink drop generation and further, the time of initiation of the drop charging period and the ink drop frequency are asynchronous. Thus, for a given charging period, a varying number of ink drops will be charged resulting in an averaging of the ink drops over several dot locations corresponding to a single tonal value.
An apparatus for printing a selected number of ink drops upon a medium at a plurality of discrete dot locations by means of an ink jet which generates a stream of drops at a rate f.sub.d comprising:
A method for printing a selected number of ink drops upon a medium at a plurality of discrete dot locations by means of an ink jet generating a stream of drops at a predetermined rate f.sub.d comprising the steps of:
Dependencies are inferred from the claim text.