US3708693A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Gamma corrector
Assignee: FERREX CORP
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Filing: 1971-05-19
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Granted: 1973-01-02
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Expires: 1991-05-19
Abstract
Abstract A circuit for introducing a controlled nonlinearity in the video voltage applied to the cathode ray tube of a color film printing system for making the tube display picture the analog of the photographic paper. The characteristic curve of a cathode ray tube is matched to the reflectance curve of photographic paper by operating upon a video signal with a number of parallel amplifier stages with each stage comprising a pair of transistors having the emitters connected together and to a power supply by resistors of predetermined values. Each stage has a different characteristic and the outputs are summed to establish a predetermined nonlinear amplification.
Inventors
- 👤 H Ferrier
- 👤 G Macginitie
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 22:21
CPC Classifications
G; G06; G06G; G06G7/00; G06G7/12; G06G7/26; G06G7/28; H; H04; H04N; H04N9/00; H04N9/12; H04N9/16
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
143 words
A function generator for operating upon video voltage applied to the grid of a cathode ray tube in a color film printing system to match the tube characteristic to photographic paper characteristics comprising a plurality of amplifier stages with each stage including first and second transistors with a first resistor directly connecting transistor emitters and a second resistor directly connecting the emitter of a first transistor to a power supply, the values of the resistors being predetermined to transfer transistor conduction at a predetermined rate that is different for each stage, an input terminal connected to the first transistor of each stage, a bias voltage terminal connected to a second transistor of each stage, and an output terminal connected to the output of the second transistor of each stage whereby an input signal is amplified a different predetermined amount in different signal ranges.
Claim 2
Dependent Claim
143 words
A function generator for operating upon video voltage applied to the grid of a cathode ray tube in a color film printing system to match the tube characteristic to photographic paper characteristics comprising a plurality of amplifier stages with each stage including first and second transistors with a first resistor directly connecting transistor emitters and a second resistor directly connecting the emitter of a first transistor to a power supply, the values of the resistors being predetermined to transfer transistor conduction at a predetermined rate that is different for each stage, an input terminal connected to the first transistor of each stage, a bias voltage terminal connected to a second transistor of each stage, and an output terminal connected to the output of the second transistor of each stage whereby an input signal is amplified a different predetermined amount in different signal ranges.
Claim 3
Dependent Claim
85 words
The function generator of claim 1 further defined by the first and second resistors of each stage comprising a voltage divider coupling the emitter of the first transistor to said power supply terminal through a lesser resistance than the emitter of the second transistor, means maintaining said first transistor of each stage normally conducting in the absence of input signals, and the second transistor of each stage being biased to cut-off in the absence of input signals and over a predetermined value of input signals.
Claim 4
Dependent Claim
155 words
A function generator comprising a plurality of amplifier stages with each stage including a pair of NPN transistors with first and second series connected resistors directly connecting the emitter of a second transistor of the pair to a negative power supply terminal and directly connecting the emitter of a first transistor of the pair to the junction of first and second resistors, a bias power supply terminal connected to the base of the second transistor of each amplifier stage for establishing the voltage of which the stage is nonconducting, a positive power supply terminal connected to the collector of the first transistor of each amplifier stage for maintaining the first transistor initially conducting, means connecting the collector of the second transistor of each amplifier stage to an output terminal for summing the currents of said collectors as the generator output, and an input terminal coupled to the base of the first transistor of each stage.
Claim 5
Dependent Claim
155 words
A function generator comprising a plurality of amplifier stages with each stage including a pair of NPN transistors with first and second series connected resistors directly connecting the emitter of a second transistor of the pair to a negative power supply terminal and directly connecting the emitter of a first transistor of the pair to the junction of first and second resistors, a bias power supply terminal connected to the base of the second transistor of each amplifier stage for establishing the voltage of which the stage is nonconducting, a positive power supply terminal connected to the collector of the first transistor of each amplifier stage for maintaining the first transistor initially conducting, means connecting the collector of the second transistor of each amplifier stage to an output terminal for summing the currents of said collectors as the generator output, and an input terminal coupled to the base of the first transistor of each stage.
Claim 6
Dependent Claim
57 words
The function generator of claim 3 further defined by the relative value of first and second resistors of each amplifier stage being such that the first transistor is cut off at a predetermined different value of voltage at said input terminal, whereby the amplification provided by the function generator is different in separated ranges of input voltage.
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) | 1976-01-02 | 1976-07-03 | 1977-01-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-02 | 1980-07-03 | 1981-01-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-02 | 1984-07-03 | 1985-01-02 | $7700.00 | Window Closed / Lapsed |