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Electronic Servo for Image Printing on a Serially Operated Transducer/Spot Matrix Printer

IP.com Disclosure Number: IPCOM000079991D
Original Publication Date: 1973-Oct-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Kuhn, L: AUTHOR

Abstract

A serially operated transducer/spot matrix printer has a print head capable of producing a vertical column of spots, typically covering a field paper held in a carriage. The paper is advanced after each traverse of the head. Even a slight error in the paper advance results in a visible flow if images are being printed (as opposed to characters or text). This is because the misregistration results in a straight white line running through the image (in the case of over advance).

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Electronic Servo for Image Printing on a Serially Operated Transducer/Spot Matrix Printer

A serially operated transducer/spot matrix printer has a print head capable of producing a vertical column of spots, typically covering a field paper held in a carriage. The paper is advanced after each traverse of the head. Even a slight error in the paper advance results in a visible flow if images are being printed (as opposed to characters or text). This is because the misregistration results in a straight white line running through the image (in the case of over advance).

In order to improve this misregistration problem, a means is suggested for electronically sensing the position of the print head relative to the previously printed band of an image, and electronically correcting for misregistration. Any slight remaining error may be smoothed out by using half-position elements to print a quasi-random pattern, correlated to the first element of the line being printed.

Fig. 1 indicates the modification in a multiple head transducer for locating the position of a head. The approach is to lay down a pattern at the edge of the page and utilize a sensor built into the head to sense the advance of the paper. At the end of a band (line) of print, a bar code pattern is produced by activating elements (-3, -1, 1, 3, --- 39, 41, 43). As the paper is advanced, the sensor monitors the advancement since it is scanned vertically along the bar pattern. The sensor might be optical (a f...