The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 17, 1987
Filed:
May. 28, 1985
Richard W Midland, Inverness, IL (US);
Zenith Electronics Corporation, Glenview, IL (US);
Abstract
A wide-band single beam index signal system includes a photo multiplier tube supplying a decay compensation circuit for developing an output signal responsive to excitation of index strips by the electron beam of the CRT. The output signal is supplied to a differentiator to determine its zero crossing and supplied to a comparator circuit where an index signal pulse is developed. The timing of the index signal is determined by the zero crossing. Video information is clocked from a computer, on a pixel-by-pixel basis, under control of the index signal. The index signal also controls production of a first index video signal and a second index video signal, depending upon the presence or absence of video information. Means are included for turning off the electron beam between index strips. The output of the differentiator is offset for noise compensation. An offset adjustment transistor is included for changing the offset to compensate for the greater excitation of the index strip in the presence of video and to thereby maintain the zero crossing reference.