Browse Prior Art Database

Scanner Control System for Image Compression

IP.com Disclosure Number: IPCOM000094010D
Original Publication Date: 1966-Apr-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Dodd, PD: AUTHOR

Abstract

A cathode ray tube beam scanning velocity control is shown. In drawing A, CRT scanner 10 detects data from document 11 which is converted in coder 12. The data is transmitted via shift register 13 to output 14. Control counter 15 controls the stepping of register 13 and also provides an output 16 for each digit detected by coder 12.

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Scanner Control System for Image Compression

A cathode ray tube beam scanning velocity control is shown. In drawing A, CRT scanner 10 detects data from document 11 which is converted in coder 12. The data is transmitted via shift register 13 to output 14. Control counter 15 controls the stepping of register 13 and also provides an output 16 for each digit detected by coder 12.

In drawings A and B, digital output 16 is converted to an analog voltage 17 and inverted at 18 by error signal converter 19. The resultant voltage is applied to velocity control 20. The latter includes a voltage-controlled multivibrator 21. This provides a higher frequency output in response to a higher voltage and vice versa. Thus, the frequency of the MV varies inversely to the output of the counter. The base waveforms 22 of the MV are combined at 23 and used to directly control the CRT scanning yoke 24.

In drawing C, since the slope of the MV waveform 25 is inversely proportional to the counter output 26, the CRT beam scans faster when the count is low and slower when the count is high.

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