Patent US4560910A successfully refreshed from Google Patents.
US4560910A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Parabolic waveform generator
Assignee: Zenith Electronics LLC
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Filing: 1984-01-19
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Granted: 1985-12-24
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Expires: 2004-01-19
Abstract
Abstract A dynamic focusing circuit for a CRT includes a DC coupled parabolic voltage waveform generator having a first capacitor supplied with constant charging current from a transistor for developing a sawtooth voltage waveform thereacross, a first switch transistor for discharging the first capacitor at a horizontal frequency rate, a second capacitor DC coupled to the first capacitor through a voltage-to-current generator transistor for developing a parabolic voltage waveform thereacross and a second switch transistor for discharging the second capacitor in synchronism with the first capacitor. Tilt and amplifier control transistors are DC coupled to the second capacitor. A vertical rate parabolic correction waveform is also developed by similar circuitry. The upper transistor in a cascode amplifier develops a high voltage replica of both the horizontal and vertical parabolic correction waveform voltages for application to the focus electrode of a CRT. Horizontal and a vertical amplifier transistors are coupled in parallel in the lower portion of the cascode amplifier and are supplied with the corresponding parabolic correction voltages.
Inventors
- 👤 Richard W. Midland
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 16:54
CPC Classifications
H; H04; H04N; H04N3/00; H04N3/10; H04N3/16; H04N3/26
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
103 words
A DC coupled parabolic voltage generator for use in a dynamic focussing system for a CRT comprising: first means including a current source transistor for supplying a substantially constant charging current to a first capacitor for developing a sawtooth voltage; second means including a voltage-to-current generator transistor for supplying a sawtooth shaped charging current to a second capacitor for developing a parabolic voltage in response to said sawtooth voltage; and means comprising transistor switches coupled across said first and said second capacitors for controlling the charging time of both said first and said second capacitors as a function of a common timing signal.
Claim 2
Dependent Claim
103 words
A DC coupled parabolic voltage generator for use in a dynamic focussing system for a CRT comprising: first means including a current source transistor for supplying a substantially constant charging current to a first capacitor for developing a sawtooth voltage; second means including a voltage-to-current generator transistor for supplying a sawtooth shaped charging current to a second capacitor for developing a parabolic voltage in response to said sawtooth voltage; and means comprising transistor switches coupled across said first and said second capacitors for controlling the charging time of both said first and said second capacitors as a function of a common timing signal.
Claim 3
Dependent Claim
14 words
The generator of claim 1 further including DC coupled tilt and amplitude control transistors.
Claim 4
Dependent Claim
35 words
The generator of claim 2 further including a switch transistor generating said common timing signal for operating said transistor switches to discharge said first and said second capacitors in synchronism with said common timing signal.
Claim 5
Dependent Claim
44 words
The generator of claim 3 wherein said second capacitor is directly coupled to the collector-emitter circuit of said tilt control transistor, and further including; means for changing the conductivity of said tilt control transistor to alter the DC current flow in said second capacitor.
Claim 6
Dependent Claim
22 words
The generator of claim 4 wherein all said elements except said first and said second capacitors are fabricated in an integrated circuit.
Claim 7
Dependent Claim
96 words
A DC coupled parabolic voltage generator for use in a dynamic focussing system for a CRT comprising: first means including a first capacitor and a first transistor supplying a substantially constant charging current thereto for developing a sawtooth voltage; second means including a voltage-to-current generator transistor coupled to a second capacitor for supplying a sawtooth charging current to said second capacitor, responsive to said sawtooth voltage, for developing a parabolic voltage; and first and second transistor switches coupled across said first and second capacitors, respectively for discharging said capacitors in response to a common timing signal.
Claim 8
Dependent Claim
96 words
A DC coupled parabolic voltage generator for use in a dynamic focussing system for a CRT comprising: first means including a first capacitor and a first transistor supplying a substantially constant charging current thereto for developing a sawtooth voltage; second means including a voltage-to-current generator transistor coupled to a second capacitor for supplying a sawtooth charging current to said second capacitor, responsive to said sawtooth voltage, for developing a parabolic voltage; and first and second transistor switches coupled across said first and second capacitors, respectively for discharging said capacitors in response to a common timing signal.
Claim 9
Dependent Claim
25 words
The generator of claim 6 including means responsive to a synchronizing signal for generating said common timing signal for said first and second transistor switches.
Claim 10
Dependent Claim
36 words
The generator of claim 7 further including a tilt control transistor DC coupled across said second capacitor; and means for changing the conduction of said tilt control transistor to drain DC current from said second capacitor.
Claim 11
Dependent Claim
117 words
A dynamic focussing circuit for a CRT comprising: first capacitor means and first transistor switch means for developing a sawtooth voltage; second capacitor means and second transistor switch means for developing a parabolic voltage responsive to said sawtooth voltage; said second capacitor means including voltage-tocurrent generator means DC coupled to said first capacitor means; means for applying a common synchronizing timing signal to said first and to said second transistor switch means to control and synchronize the development of said sawtooth voltage and said parabolic voltage; high voltage cascode amplifier means having an input transistor coupled to receive said parabolic voltage; and means for coupling the output of said high voltage cascode amplifier means to said CRT.
Claim 12
Dependent Claim
117 words
A dynamic focussing circuit for a CRT comprising: first capacitor means and first transistor switch means for developing a sawtooth voltage; second capacitor means and second transistor switch means for developing a parabolic voltage responsive to said sawtooth voltage; said second capacitor means including voltage-tocurrent generator means DC coupled to said first capacitor means; means for applying a common synchronizing timing signal to said first and to said second transistor switch means to control and synchronize the development of said sawtooth voltage and said parabolic voltage; high voltage cascode amplifier means having an input transistor coupled to receive said parabolic voltage; and means for coupling the output of said high voltage cascode amplifier means to said CRT.
Claim 13
Dependent Claim
70 words
The focusing circuit of claim 9 wherein said high voltage cascode amplifier means include a second input transistor coupled in parallel with said input transistor and wherein means are provided for generating a second parabolic voltage for application to said second input transistor, said parabolic voltage and said second parabolic voltage each being at a frequency corresponding to one of the horizontal and vertical scanning frequencies, respectively, for said CRT.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-12-23 | 1989-06-24 | 1989-12-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-12-23 | 1993-06-24 | 1993-12-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-12-23 | 1997-06-24 | 1997-12-24 | $7700.00 | Window Closed / Lapsed |