US4230974A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Cathode ray tube deflection circuit having display format selection
Assignee: AT&T Teletype Corp
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Filing: 1979-04-16
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Granted: 1980-10-28
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Expires: 1999-04-16
Abstract
Abstract A cathode ray tube deflection circuit is described which selects between two display formats in response to a format control signal. A horizontal deflection portion includes the primary winding of a flyback transformer resonant with a horizontal deflection yoke. Switches are connected across a portion of the primary winding and across portions of the yoke. A logic unit, in response to the control signal, actuates each of the switches to change the resonant frequency of the horizontal deflection circuit. The logic unit correspondingly changes the frequency of the horizontal drive signal and the amplitude of the vertical sweep.
Inventors
- 👤 Gary R. Haak
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 05:57
CPC Classifications
G; G09; G09G; G09G1/00; G09G1/04
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
252 words
An apparatus for selectively changing the display on the screen of a cathode ray tube from a first format to a second format in response to a format control signal including a horizontal deflection circuit 10 having an inductance 16, 30 with a first inductive value resonated with a capacitor 37 to a first horizontal sweep frequency, means 26 for generating a horizontal drive signal 24 in response to the format selection signal for driving the horizontal deflection circuit 10, the horizontal deflection circuit 20 determining the horizontal size of the display, means 26, 40, 42, 44, responsive to the control signal 27, for changing the inductive value of said inductance 16, 30 to a second value and thus changing the resonant frequency of the horizontal deflection circuit to a second value, means 26 responsive to the control signal 27, for changing the frequency of said horizontal drive signal to a second frequency related to the second resonant frequency of the horizontal deflection circuit 10, and a vertical deflection circuit 12 including means 26 responsive to the format control signal for varying the amplitude of the output of the vertical deflection circuit from a first value to a second value CHARACTERIZED BY: said horizontal deflection circuit inductance 16, 30 including a yoke 30 and said inductive value changing means 26, 40, 42, 44 including a switch 40, 42 for effectively shorting at least a portion of the turns of said yoke 30 so as to reduce the inductance of the yoke 30.
Claim 2
Independent Claim
252 words
An apparatus for selectively changing the display on the screen of a cathode ray tube from a first format to a second format in response to a format control signal including a horizontal deflection circuit 10 having an inductance 16, 30 with a first inductive value resonated with a capacitor 37 to a first horizontal sweep frequency, means 26 for generating a horizontal drive signal 24 in response to the format selection signal for driving the horizontal deflection circuit 10, the horizontal deflection circuit 20 determining the horizontal size of the display, means 26, 40, 42, 44, responsive to the control signal 27, for changing the inductive value of said inductance 16, 30 to a second value and thus changing the resonant frequency of the horizontal deflection circuit to a second value, means 26 responsive to the control signal 27, for changing the frequency of said horizontal drive signal to a second frequency related to the second resonant frequency of the horizontal deflection circuit 10, and a vertical deflection circuit 12 including means 26 responsive to the format control signal for varying the amplitude of the output of the vertical deflection circuit from a first value to a second value CHARACTERIZED BY: said horizontal deflection circuit inductance 16, 30 including a yoke 30 and said inductive value changing means 26, 40, 42, 44 including a switch 40, 42 for effectively shorting at least a portion of the turns of said yoke 30 so as to reduce the inductance of the yoke 30.
Claim 3
Dependent Claim
73 words
The apparatus of claim 1 further characterized by said horizontal deflection circuit 10 including a flyback transformer 14 having a primary winding 16 and said inductive value charging means 26, 40, 42, 44 including a switch 44 connected across a portion of said primary winding 16 for shorting a portion of said primary winding 16 thereby changing the inductive value of the primary winding 16 in response to the format control signal 27.
Claim 4
Dependent Claim
51 words
The apparatus of claim 2 further characterized by said horizontal deflection yoke 30 defines a plurality of portions 30a and 30b and with a switch 40, 42 connected across each portion of the yoke winding for effectively changing the inductive value of the yoke in response to said control signal 27.
Claim 5
Dependent Claim
32 words
The apparatus of claim 3 further characterized by said primary winding 16 and said yoke 30 are series resonant with a capacitor 36 at the frequency of said horizontal drive signal 24.
References Cited (Backward Citations)
US3559207A
Cited
US3903517A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-10-28 | 1984-04-28 | 1984-10-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-10-28 | 1988-04-28 | 1988-10-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-10-28 | 1992-04-28 | 1992-10-28 | $7700.00 | Window Closed / Lapsed |