CA1173977A
Expired / Lapsed
CA
⏱️ 0.0 years remaining
Regulation of the scan width of a raster scanned crt deflection system
Assignee: Electrohome Ltd
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Filing: 1981-03-31
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Granted: 1984-09-04
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Expires: 2001-03-31
Abstract
Abstract ABSTRACT OF THE DISCLOSURE The input voltage to the deflection system of a raster scanned CRT is made variable and is controlled by a feedback network in such a way that the width of the raster remains constant regardless of scanning fre- quency variations.
Inventors
- 👤 Terrance C. Schmidt
Bibliographic Details
Application Number
—
Jurisdiction
CA
Data Source
google_patents
Last Synchronized
2026-11-06 02:39
CPC Classifications
H; H04; H04N; H04N3/00; H04N3/10; H04N3/16; H04N3/22; H04N3/23
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
146 words
-7- CLAIMS: 1. In combination with a horizontal scanning system for a CRT, said system being of the resonant shunt efficiency type and including a horizontal deflection coil; means for supplying a variable frequency drive signal to said scanning system to produce a horizontal scan of variable frequency; a variable output voltage power supply for supplying a variable power supply voltage to said horizontal scanning system; means for deriving an error signal indicative of a change in magnitude of deflection current in said coil from a predetermined magnitude; and means for supplying said error signal to said variable output voltage power supply to decrease said voltage in response to an increase in said deflection current and to increase said voltage in response to a decrease in said deflection current, thereby to maintain said deflection current substantially constant regardless of changes in frequency of the horizontal scan.
Claim 2
Dependent Claim
50 words
The invention according to claim 1 wherein said means for deriving said error signal include means for deriving a D.C. voltage that is proportional to the peak to peak value of said deflection current in said coil and for comparing said D.C. voltage to a D.C. voltage of predetermined magnitude.
Claim 3
Dependent Claim
99 words
The invention according to claim 1 including a vertical deflection coil; means for deriving therefrom a vertical deflection waveform; means for inverting said vertical deflection waveform; means for applying said vertical deflection waveform and the inverted vertical deflection waveform to opposite ends of a potentiometer; means for deriving from said potentiometer a correction voltage; and means for utilizing said correction voltage to change said power supply voltage supplied to said horizontal scanning system to increase or decrease said deflection current in said horizontal -8- deflection coil at the top or bottom of the scan to compensate for optical keystone.
Claim 4
Dependent Claim
44 words
The invention according to claim 2 including a vertical scanning system including a vertical deflection coil providing a vertical deflection waveform, and means for varying said power supply voltage in response to variations in said vertical deflection waveform to compen- sate for optical keystone.
Claim 5
Dependent Claim
62 words
The invention according to claim 2 including a vertical scanning system including a vertical deflection coil providing a vertical deflection waveform, means for inverting said vertical deflection waveform to provide an inverted vertical deflection waveform, and means for varying said power supply voltage in response to either said vertical deflection waveform or said inverted vertical deflection waveform to compensate for optical keystone.
References Cited (Backward Citations)
No citation records indexed.
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