Patent US4945292A successfully refreshed from Google Patents.
US4945292A
Expired / Lapsed
US
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Dynamic vertical height control circuit
Assignee: Unisys Corp
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Filing: 1988-08-08
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Granted: 1990-07-31
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Expires: 2008-08-08
Abstract
Abstract The present invention provides a novel dynamic vertical height control circuit for a CRT display which is adapted to receive an input signal over a broad range of variable frequencies. The dynamic variable input frequency is applied to a free running oscillator which is coupled to a ramp generator for producing a ramp output signal. The ramp output signal is coupled back through novel feedback means comprising a comparator and means for determining the magnitude of the ramp output signal voltage for producing a feedback signal which is applied as a control signal to the ramp generator. The feedback control maintains a vertical height control signal which maintains a constant vertical display size on the CRT display.
Inventors
- 👤 Bruce D. Ackerson
- 👤 Stephen J. Paker
- 👤 Clayton C. Wahlquist
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 20:34
CPC Classifications
H; H04; H04N; H04N3/00; H04N3/10; H04N3/16; H04N3/27; H03; H03K; H03K4/00; H03K4/06; H03K4/08; H03K4/48; H03K4/60; H03K4/69; H03K6/00; H03K6/04
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
117 words
A dynamic vertical height control circuit comprising: variable frequency oscillator means for receiving a dynamic variable frequency input, ramp generator means coupled to the output of said oscillator means for generating a constant amplitude deflection ramp signal, feedback means coupled to the output of said ramp generator means for generating a constant level gain control signal which is applied to the gain control of the ramp generator for maintaining a constant amplitude ramp signal from said ramp generator over a range of frequencies, said feedback means comprising a comparator in a feedback loop having a voltage reference input and an analog voltage input indicative of the average analog voltage generated from the output of said ramp generator.
Claim 2
Dependent Claim
117 words
A dynamic vertical height control circuit comprising: variable frequency oscillator means for receiving a dynamic variable frequency input, ramp generator means coupled to the output of said oscillator means for generating a constant amplitude deflection ramp signal, feedback means coupled to the output of said ramp generator means for generating a constant level gain control signal which is applied to the gain control of the ramp generator for maintaining a constant amplitude ramp signal from said ramp generator over a range of frequencies, said feedback means comprising a comparator in a feedback loop having a voltage reference input and an analog voltage input indicative of the average analog voltage generated from the output of said ramp generator.
Claim 3
Dependent Claim
37 words
A dynamic vertical height control circuit as set forth in claim 1 wherein said feedback means comprises a peak sample and hold circuit connected to the buffered output of said ramp generator coupled in the feeback loop.
Claim 4
Dependent Claim
26 words
A dynamic vertical height control circuit as set forth in claim 2 wherein said feedback means further comprises an integrator amplifier coupled in the feedback loop.
Claim 5
Dependent Claim
19 words
A dynamic vertical height control circuit as set forth in claim 3 wherein said integrator amplifier includes said comparator.
Claim 6
Dependent Claim
27 words
A dynamic vertical height control circuit as set forth in claim 1 wherein said feedback means comprises a frequency to voltage converter means in the feedback loop.
Claim 7
Dependent Claim
23 words
A dynamic vertical height control circuit as set forth in claim 5 wherein said frequency to voltage converter further comprises said comparator means.
Claim 8
Dependent Claim
38 words
A dynamic vertical height control circuit as set forth in claim 1 which further includes a buffer converter coupled to the output of said feedback control means for converting a voltage feedback signal to a current feedback signal.
Claim 9
Dependent Claim
26 words
A dynamic vertical height control circuit as set forth in claim 7 wherein said buffer converter comprises a pair of transistors connected as a current mirror.
Claim 10
Dependent Claim
21 words
A dynamic height control circuit as set forth in claim 1 wherein said feedback means comprises a low noise feedback loop.
References Cited (Backward Citations)
US4682087A
Cited
US4746842A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-07-30 | 1994-01-29 | 1994-07-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-07-30 | 1998-01-29 | 1998-07-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-07-30 | 2002-01-29 | 2002-07-31 | $7700.00 | Window Closed / Lapsed |