International Business Machines Corporation

Carol E Wyke

Phuc Ky Do

Demetrios Troupes

Nicholas J Krull

Tim V Angst

Dennis R Hedrick

Ronnie Chi-on Tong

Karen K Kellam

Ronald W Willis

Mark E Bunke

Barnes R Kendrick, Jr

This invention relates to a method for generating character images using a font compression algorithm that reduces the storage requirements associated with low-cost, high resolution printers. An expanded character image has original print slices and duplicate print slices identical to one or more of the original print slices where the duplicate print slices are eliminated in the compressed character image. The compressed character is expanded using a repetition mask that identifies the number and location of the duplicate print slices. The technique for expanding the compressed character is such that printing can be performed in real time, in either a forward or reverse direction with only minimal effects on processing. This invention also provides a means for supporting multiple pitches, such as 10 CPI, 12 CPI and Proportional Space Mode (PSM), within those storage constraints. The technique of this invention is efficient enoughh to be performed by microcode in real time, yet provides for significant reduction in the overall memory required for storing the font data.

Method and apparatus for generating a character image

A method and apparatus for quieting the operation of a dot matrix printer by logically dividing the data to be printed among timed spaced printing passes is disclosed. A matrix of data to be printed is stored in a memory. A slice of data is selected from the stored data and the number of dots to be printed simultaneously is reduced by logically allocating the data in each slice among complementary submatrices. Each submatrix of data is printed substantially aligned with each other submatrix in two passes of the print head across the print medium to represent the entire selected slice of data. Noise reduction is achieved by reducing the number of data dots simultaneously printed at each print location.

Method and apparatus for quieting the operation of a dot matrix printer

Where the ribbon advance mechanism of a printer is driven by the motion of the print head carrier, ink in the ribbon will be differentially depleted depending upon the density of print. This varied depletion becomes a problem for printers capable of printing high density graphics images, particularly color filled images. In accordance with this invention, the printing density is monitored and when the printing density exceeds a predetermined value, the print head is caused to be moved an amount greater than that necessary to position the print head at a succeeding print position so as to thereby cause additional ink ribbon to be advanced and to avoid overprinting on areas of the ribbon where high density printing has occurred.

Ribbon feed with ink depletion compensation

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Charlotte, NC, United States of America

Carol E Wyke