Browse Prior Art Database

Composite Video Adapter for Display Copier

IP.com Disclosure Number: IPCOM000046978D
Original Publication Date: 1983-Sep-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 65K

Publishing Venue

IBM

Related People

Allan, J: AUTHOR [+2]

Abstract

A thermal printer, which composes images (either print characters or graphics) by thermal transfer of "dot" picture elements in a line scan raster pattern, is adaptable by means described here to reproduce images from composite video signals of the type used in commercial television CRT displays. Composite video signals of this type are analog in form and may define various colors as well as shades of grey tones (black/white intensity). In the present reproductions the dots are formed as on/off binary functions and grey tones and colors are not discernible. Referring to Fig. 1, sync detector circuit 1 detects the horizontal synch signal embedded in the composite video (demodulated) and applies it to phase-locked loop 2, the latter consisting of phase detector 2a, voltage-controlled oscillator 2b, and divider circuit 2c.

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Composite Video Adapter for Display Copier

A thermal printer, which composes images (either print characters or graphics) by thermal transfer of "dot" picture elements in a line scan raster pattern, is adaptable by means described here to reproduce images from composite video signals of the type used in commercial television CRT displays. Composite video signals of this type are analog in form and may define various colors as well as shades of grey tones (black/white intensity). In the present reproductions the dots are formed as on/off binary functions and grey tones and colors are not discernible. Referring to Fig. 1, sync detector circuit 1 detects the horizontal synch signal embedded in the composite video (demodulated) and applies it to phase-locked loop 2, the latter consisting of phase detector 2a, voltage-controlled oscillator 2b, and divider circuit 2c. Assuming operation relative to a display copier having 800-dot print positions per copy line, divider 2c is designed to divide the frequency output of oscillator 2b by a multiple of 800, as shown. The video signal exiting from detector 1 is digitized by comparator 3 which applies a corresponding binary signal level to sample logic 4. The comparator is designed with hysteresis to reduce noise susceptibility. The binary dot data generated by sample logic 4 is applied to the display copier (thermal printer) system, via bus 5, together with dot timing signals, the latter developed from the oscillator output b...