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Print Current Adjustment for Electrothermal Printers

IP.com Disclosure Number: IPCOM000050150D
Original Publication Date: 1982-Sep-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 67K

Publishing Venue

IBM

Related People

Long, TH: AUTHOR [+2]

Abstract

Special purpose logic and apparatus adjust current levels for a matrix type of electrothermal printer in accordance with measurements of print samples.

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Print Current Adjustment for Electrothermal Printers

Special purpose logic and apparatus adjust current levels for a matrix type of electrothermal printer in accordance with measurements of print samples.

Referring to Fig. 1, a solid fill and a 50 percent fill pattern are printed to provide information for adjusting printing current (or voltage) levels. Measurements regarding the patterns are taken using a light source 10 (Fig. 3) and photocell 12 that are preferably mounted on the printhead carrier (not shown). The signal from the photocell 12 is amplified by amplifier 14 and is sampled by an analog to digital (A/D) converter 16. A machine processor 18 includes the adjustment logic and receives sample information in coded form from the A/D converter 16. Sampling events for the A/D converter 16 occur under the control of the machine processor 18 and are triggered using a control line 20.

The adjustment logic (Fig. 2) is entered when a ribbon is loaded (block 50). A test (block 102) for paper presence (e.g., based on reflection) indicates a need for paper loading (block 104) in the event of a negative result and allows pattern printing to begin (block 106) for a positive result.

The patterns are examined (block 108), and based on density comparisons to reference values, current adjustments are made (blocks 110 and 112) for out of range values with a subsequent printing of new patterns (block 114). If the patterns fall in the acceptable range, then the adjust logic...