US4612574A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Oscillator-frequency control interface circuit
Assignee: RCA Licensing Corp
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Filing: 1983-10-14
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Granted: 1986-09-16
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Expires: 2003-10-14
Abstract
Abstract A video display apparatus having automatic frequency control circuitry for adjusting the frequency of a horizontal oscillator to provide oscillator synchronization with incoming horizontal synchronizing pulses incorporates an interface circuit for controlling the horizontal oscillator frequency response to frequency control output voltage. The interface circuit incorporates a two-transistor switch which provides a current path for charging the horizontal oscillator timing capacitor during a portion of the horizontal interval and a current path for bypassing the horizontal oscillator timing capacitor during another portion of the horizontal interval. The amplitude of the frequency control output voltage will determine the relative length of time that each of the transistors is conducting in order to provide a net increase or decrease rate in the charging of the oscillator capacitor, which in turn adjusts the oscillator operating frequency.
Inventors
- 👤 Robert A. Barnes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 14:29
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/04; H04N5/12; H04N5/126; H04N3/00; H04N3/10; H04N3/16
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
221 words
A video display apparatus comprising: a line deflection circuit providing retrace pulses and incorporating a line rate oscillator having a capacitor, the operating frequency of said oscillator determined by the charge and discharge rate of said capacitor; a source of line rate synchronizing pulses; frequency control means responsive to said retrace pulses and to said line rate synchronizing pulses for providing an output signal having an amplitude determined by the phase relationship between said retrace pulses and said line rate synchronizing pulses; interface means comprising switch means having a first terminal coupled to said frequency control means output signal and a second terminal coupled to said capacitor of said line rate oscillator, said switch means also having a third terminal coupled to a source of voltage and a fourth terminal coupled to a source of reference potential, said switch means providing a first current path from said source of voltage potential to said capacitor for increasing the charging rate of said capacitor when the amplitude of said frequency control means output signal exceeds a first predetermined level, said switch means providing a second current path from said source of voltage potential to said source of reference potential for decreasing the charging rate of said capacitor when the amplitude of said frequency control means output signal is below a second predetermined level.
Claim 2
Dependent Claim
221 words
A video display apparatus comprising: a line deflection circuit providing retrace pulses and incorporating a line rate oscillator having a capacitor, the operating frequency of said oscillator determined by the charge and discharge rate of said capacitor; a source of line rate synchronizing pulses; frequency control means responsive to said retrace pulses and to said line rate synchronizing pulses for providing an output signal having an amplitude determined by the phase relationship between said retrace pulses and said line rate synchronizing pulses; interface means comprising switch means having a first terminal coupled to said frequency control means output signal and a second terminal coupled to said capacitor of said line rate oscillator, said switch means also having a third terminal coupled to a source of voltage and a fourth terminal coupled to a source of reference potential, said switch means providing a first current path from said source of voltage potential to said capacitor for increasing the charging rate of said capacitor when the amplitude of said frequency control means output signal exceeds a first predetermined level, said switch means providing a second current path from said source of voltage potential to said source of reference potential for decreasing the charging rate of said capacitor when the amplitude of said frequency control means output signal is below a second predetermined level.
Claim 3
Dependent Claim
38 words
The arrangement defined in claim 1, wherein said interface means further comprises an impedance coupled between said switch means third terminal and said source of voltage potential for limiting the amount of charging rate increase of said capacitor.
Claim 4
Dependent Claim
38 words
The arrangement defined in claim 1, wherein said interface means further comprises an impedance coupled between said switch means fourth terminal and said source of reference potential for limiting the amount of charge rate decrease of said capacitor.
Claim 5
Dependent Claim
57 words
The arrangement defined in claim 1, wherein said interface means further comprises an impedance coupled between said source of voltage potential and said switch means first terminal, and an impedance coupled between said switch means first terminal and said source of reference potential for providing operation of said switch means in the absence of said synchronizing pulses.
Claim 6
Dependent Claim
15 words
The arrangement defined in claim 1, wherein said switch means comprises first and second transistors.
Claim 7
Dependent Claim
14 words
The arrangement defined in claim 1, wherein said second current path bypasses said capacitor.
Claim 8
Dependent Claim
167 words
A video display apparatus comprising: a line deflection circuit providing retrace pulses and incorporating a line rate oscillator having a capacitor, the operating frequency of said oscillator determined by the charge and discharge rate of said capacitor; a source of line rate synchronizing pulses; frequency control means responsive to said retrace pulses and to said line rate synchronizing pulses for providing an output signal having an amplitude determined by the phase relationship between said retrace pulses and said line rate synchronizing pulses; interface means comprising a switch means having an input coupled to said frequency control means output signal and an output coupled to said capacitor, said switch means responsive to said frequency control means output signal for providing a current path from a source of voltage potential to said capacitor for charging said capacitor, said switch means responsive to said frequency control means output signal for providing a current path from said source of voltage potential to a source of reference potential for bypassing said capacitor.
Claim 9
Dependent Claim
167 words
A video display apparatus comprising: a line deflection circuit providing retrace pulses and incorporating a line rate oscillator having a capacitor, the operating frequency of said oscillator determined by the charge and discharge rate of said capacitor; a source of line rate synchronizing pulses; frequency control means responsive to said retrace pulses and to said line rate synchronizing pulses for providing an output signal having an amplitude determined by the phase relationship between said retrace pulses and said line rate synchronizing pulses; interface means comprising a switch means having an input coupled to said frequency control means output signal and an output coupled to said capacitor, said switch means responsive to said frequency control means output signal for providing a current path from a source of voltage potential to said capacitor for charging said capacitor, said switch means responsive to said frequency control means output signal for providing a current path from said source of voltage potential to a source of reference potential for bypassing said capacitor.
Claim 10
Dependent Claim
108 words
In a video display apparatus incorporating automatic frequency control circuitry and a line rate oscillator, an interface circuit comprising: means responsive to an output signal from said automatic frequency control circuitry for establishing a direct voltage level representative of the level of said output signal; means responsive to said direct voltage for applying an adjustment signal to said line rate oscillator, wherein said interface circuit comprises first and second transistors for increasing current flow to said line rate oscillator when direct voltage is above a first predetermined level and for decreasing current flow to said line rate oscillator when said direct voltage is below a second predetermined level.
Claim 11
Dependent Claim
108 words
In a video display apparatus incorporating automatic frequency control circuitry and a line rate oscillator, an interface circuit comprising: means responsive to an output signal from said automatic frequency control circuitry for establishing a direct voltage level representative of the level of said output signal; means responsive to said direct voltage for applying an adjustment signal to said line rate oscillator, wherein said interface circuit comprises first and second transistors for increasing current flow to said line rate oscillator when direct voltage is above a first predetermined level and for decreasing current flow to said line rate oscillator when said direct voltage is below a second predetermined level.
References Cited (Backward Citations)
US3241084A
Cited
US3319179A
Cited
US3937876A
Cited
US3873766A
Cited
US4047223A
Cited
US4155049A
Cited
US4327376A
Cited
US4228463A
Cited
US4266245A
Cited
GB2083721A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-09-15 | 1990-03-17 | 1990-09-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-09-15 | 1994-03-17 | 1994-09-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-09-15 | 1998-03-17 | 1998-09-16 | $7700.00 | Window Closed / Lapsed |