US 4,158,203 AGranted

Arrangement for recording images appearing on a cathode ray tube

AssigneeBuckeye International, Inc.

InventorsClark E. Johnson, Jr., William F. Main

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Abstract

An arrangement for making a hard copy of a cathode ray tube display. Each horizontal line of a video signal is subdivided into a predetermined number of intervals. The amplitude of the video signal within each interval is digitized, and the digitized data, after being stored in a first-in-first-out shift register, is recorded on any desired recording medium, such as heat-sensitive or electro-sensitive paper. Each horizontal line is printed along a line on the paper, and the paper is advanced by one line when the next horizontal line of the video signal is ready to be recorded. The subdividing of each horizontal line is carried out by a phase-lock loop which functions as a frequency multiplier and provides a predetermined number of pulses for each horizontal sync pulse. Each horizontal line being processed is identified by a line counter to ensure that the horizontal lines of a frame are sequentially printed. The digitizing of the amplitude of the video signal permits printing of gray intensities of the video signal displayed on the cathode ray tube. A frequency-controlled oscillator provides image darkness by determining the duration of current applied to the printing element against the sensitive paper for recording the information taken from the shift register.

Claims12

Dependent claims

An arrangement for making a recording of an image displayed on a cathode ray tube for a selected substantially short duration of time, comprising line identifying means for identifying and recording sequentially a horizontal line of an image on said cathode ray tube to be recorded;

dividing means connected to said line identifying means for dividing said horizontal line into a predetermined number of intervals;
means for digitizing the amplitude of a video signal corresponding to said horizontal line within each of said intervals;
storage means connected to said amplitude digitizing means and to said dividing means for storing digitized amplitudes within each interval;
recording means connected to said storage means for recording within a predetermined time duration the digitized amplitudes transmitted from said storage means;
said line identifying means comprises sync separator means for receiving said video signal and for generating horizontal sync pulses and vertical sync pulses, first counter means connected to said sync separator means and operable to be advanced by said horizontal sync pulses and to be reset by said vertical sync pulses, second counter means connected to said recording means and advanced by pulses from said recording means;
and magnitude comparator means having inputs connected to said first counter means and said second counter means for comparing the contents of said first and second counter means, said magnitude comparator means having an output for controlling said storage means.

3 more elements

Dependencies are inferred from the claim text.