US3854006A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Switchable video amplifier
Assignee: RCA Licensing Corp
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Filing: 1973-10-23
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Granted: 1974-12-10
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Expires: 1993-10-23
Abstract
Abstract A video frequency amplifier is biased to provide output signals of a first magnitude. In response to the application of a predetermined control signal, the bias is altered so that output signals are provided of a second, different magnitude. When employed in communications systems of the type in which television images are ''''frozen'''' by a storage tube for subsequent transmission on an individual frame basis by a voice-quality telephone link, for example, and subsequently re-created, the control signal indicates whether the system and its storage tube are to operate either in the ''''transmit'''' or ''''receive'''' mode. Power dissipation is kept low by energizing the amplifier only during those times when input signals are applied for amplification.
Inventors
- 👤 D Dorsey
- 👤 W Rodda
- 👤 K Bahrs
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 10:15
CPC Classifications
H; H04; H04N; H04N7/00; H04N7/12
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
369 words
In a television image transmission system of the type wherein a single storage device is controllably biased to ''''write,'''' ''''read'''' and ''''erase'''' modes of operation both for the selection of a particular frame of television information for transmission to a remote receiver location by an audio communications link and for the reception and re-creation of frame information so transmitted, and in which there is included: an amplifier stage having an input terminal to which image representative television information is supplied and an output terminal at which amplified versions of said image representative information is developed for application to said storage device for the selection or re-creation of said information dependent upon when said device is operating within said system in the transmitting or receiving mode; first means for biasing said amplifier stage to develop amplified image representative signals of a first magnitude at its output terminal referenced to a first direct current level; second means for biasing said amplifier stage to develop amplified image representative signals of a second, different magnitude at its output terminal referenced to a second, different direct current level; and first control means coupled to said first and second biasing means for conditioning at least one of said biasing means to operation to set the magnitude of developed amplified signals and the direct current level to which said amplified signals are referenced; said first control means also being dependent upon the mode of operation of said storage device within said television image transmission system to establish Class A amplifier operation and said first signal magnitude and direct current level as a reference when said storage device is employed to select a particular television frame for transmission and to establish Class B amplifier operation and said second signal magnitude and direct current level as a reference when said storage device is employed to re-create a television frame received along said audio communications link; the combination therewith of: second control means coupled to said amplifier stage for applying energizing potentials thereto substantially only when said storage device is biased to its ''''write'''' mode of operation, and to thereby reduce the quiescent power dissipated within said stage during the ''''read'''' and ''''erase'''' modes of operation of said device.
Claim 2
Dependent Claim
369 words
In a television image transmission system of the type wherein a single storage device is controllably biased to ''''write,'''' ''''read'''' and ''''erase'''' modes of operation both for the selection of a particular frame of television information for transmission to a remote receiver location by an audio communications link and for the reception and re-creation of frame information so transmitted, and in which there is included: an amplifier stage having an input terminal to which image representative television information is supplied and an output terminal at which amplified versions of said image representative information is developed for application to said storage device for the selection or re-creation of said information dependent upon when said device is operating within said system in the transmitting or receiving mode; first means for biasing said amplifier stage to develop amplified image representative signals of a first magnitude at its output terminal referenced to a first direct current level; second means for biasing said amplifier stage to develop amplified image representative signals of a second, different magnitude at its output terminal referenced to a second, different direct current level; and first control means coupled to said first and second biasing means for conditioning at least one of said biasing means to operation to set the magnitude of developed amplified signals and the direct current level to which said amplified signals are referenced; said first control means also being dependent upon the mode of operation of said storage device within said television image transmission system to establish Class A amplifier operation and said first signal magnitude and direct current level as a reference when said storage device is employed to select a particular television frame for transmission and to establish Class B amplifier operation and said second signal magnitude and direct current level as a reference when said storage device is employed to re-create a television frame received along said audio communications link; the combination therewith of: second control means coupled to said amplifier stage for applying energizing potentials thereto substantially only when said storage device is biased to its ''''write'''' mode of operation, and to thereby reduce the quiescent power dissipated within said stage during the ''''read'''' and ''''erase'''' modes of operation of said device.
Claim 3
Dependent Claim
56 words
The combination of claim 1 wherein said amplifier stage includes a pair of transistors coupled in cascade connected, grounded emitter amplifier configurations and wherein said second control means applies said energizing potentials to both of said pair of transistors substantially only during the time at which said storage device is biased to its ''''write'''' operational mode.
Claim 4
Dependent Claim
54 words
The combination of claim 2 wherein said second control means applies a first energizing potential substantially continuously to the input transistor of said cascade connected pair and applies a second energizing potential to the output transistor of said cascade pair substantially only when said storage device is biased to its ''''write'''' mode of operation.
Claim 5
Dependent Claim
48 words
The combination of claim 3 wherein said pair of transistors are of opposite polarity type and wherein said second control means includes a third transistor seriAlly coupled between the collector electrode of the output transistor of said cascade connected pair and an included source of energizing potential therefor.
Claim 6
Dependent Claim
39 words
The combination of claim 4 wherein there is further included means providing an input signal to bring said third transistor to a conductive state substantially only during the time said storage device is controllably biased to its ''''write'''' mode.
References Cited (Backward Citations)
US2629010A
Cited
US3628166A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-09 | 1978-06-10 | 1978-12-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-09 | 1982-06-10 | 1982-12-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-09 | 1986-06-10 | 1986-12-10 | $7700.00 | Window Closed / Lapsed |