Browse Prior Art Database

Half Tone Generation

IP.com Disclosure Number: IPCOM000091009D
Original Publication Date: 1969-Sep-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Supernowicz, EJ: AUTHOR

Abstract

Cathode ray tube photocomposition devices generate character information, for example, on photosensitive media. The photosensitive media is then processed and utilized to prepare printing plates. Generation of graphic information in a similar manner requires the ability to produce a controlled grey scale such as half-tone dots. Half-tone dots of variable areas are produced in a CRT photocomposition system by multispot generation combined with controlled wobbling of each spot. This system produces half-tone dots of variable sizes by spot-wobbling. Each spot is focussed on photosensitive media 10. Variable sized dots are produced at each point of the media by the wobbling of the CRT beam.

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Half Tone Generation

Cathode ray tube photocomposition devices generate character information, for example, on photosensitive media. The photosensitive media is then processed and utilized to prepare printing plates. Generation of graphic information in a similar manner requires the ability to produce a controlled grey scale such as half-tone dots. Half-tone dots of variable areas are produced in a CRT photocomposition system by multispot generation combined with controlled wobbling of each spot. This system produces half-tone dots of variable sizes by spot-wobbling. Each spot is focussed on photosensitive media 10. Variable sized dots are produced at each point of the media by the wobbling of the CRT beam. In this instance, wobbling of the beam is accomplished by superimposing a high-frequency sine wave onto the signal frequency at the deflection coil of the CRT. A memory and control element gates pulses to the Z axis of the CRT, while simultaneously controlling the modulation of the deflection circuit. The degree of modulation or wobble at each spot is controlled also by the memory and control element. This determines the size of each spot.

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