Patent US4737855A successfully refreshed from Google Patents.
US4737855A
Expired / Lapsed
US
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Automatic diaphragm control device for TV camera objective
Assignee: Pentax Precision Co Ltd
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Filing: 1986-06-17
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Granted: 1988-04-12
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Expires: 2006-06-17
Abstract
Abstract An automatic diaphragm control device for a TV camera objective utilizing a video signal from the TV camera includes a circuit for adjustment of a low contrast video signal, a circuit for adjustment of a high contrast video signal and for preventing variations of the low contrast video output signal previously adjustment, a circuit for stabilization of a source voltage used as a power supply, a servo circuit for halting the operation of a servomotor driving said diaphragm in response to the adjusted video signals and a feedback signal from a detecting coil of the servomotor, and for driving the servomotor by supplying a stabilized driving voltage to a driving coil, and a circuit for activating operational amplifiers respectively associated with the adjustment and voltage stabilization circuits.
Inventors
- 👤 Masayuki Arai
- 👤 Terumi Ogasawara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 15:46
CPC Classifications
H; H04; H04N; H04N23/00; H04N23/70; H04N23/75
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
176 words
An automatic diaphragm control device for a TV camera objective comprising: first adjustment means for adjusting a low contrast video signal from said TV camera; second adjustment means for adjusting a high contrast video signal from said TV camera and for preventing a video signal adjusted by said first adjustment means from being substantially varied; voltage stabilization means for stabilizing a source voltage used as a power supply for said device, to prevent variations in the video signals adjusted by said first and second adjustment means; a servomotor for driving a diaphragm of said TV camera objective including a driving coil and a detecting coil; control means for halting the operation of said servomotor in response to said adjusted video signals and a feedback signal from said detecting coil, and for driving said servomotor by applying a stabilized voltage to said driving coil; and means for providing a voltage supply to said first and second adjustment means and said control means, which voltage supply is of a predetermined value that is less than said source voltage.
Claim 2
Dependent Claim
176 words
An automatic diaphragm control device for a TV camera objective comprising: first adjustment means for adjusting a low contrast video signal from said TV camera; second adjustment means for adjusting a high contrast video signal from said TV camera and for preventing a video signal adjusted by said first adjustment means from being substantially varied; voltage stabilization means for stabilizing a source voltage used as a power supply for said device, to prevent variations in the video signals adjusted by said first and second adjustment means; a servomotor for driving a diaphragm of said TV camera objective including a driving coil and a detecting coil; control means for halting the operation of said servomotor in response to said adjusted video signals and a feedback signal from said detecting coil, and for driving said servomotor by applying a stabilized voltage to said driving coil; and means for providing a voltage supply to said first and second adjustment means and said control means, which voltage supply is of a predetermined value that is less than said source voltage.
Claim 3
Dependent Claim
40 words
An automatic diaphragm control device for a TV camera objective according to claim 1, wherein said first adjustment means comprises an operational amplifier adapted to inversely amplify a DC component of the low contrast video signal in a gain-variable manner.
Claim 4
Dependent Claim
69 words
An automatic diaphragm control device for a TV camera objective according to claim 1, wherein said first adjustment means comprises an operational amplifier adapted to inversely amplify a DC component of the low contrast video signal in a gain-variable manner and said second adjustment means comprises a diode adapted to suppress a negative signal portion of an output signal from the operational amplifier serving as the first adjustment means.
Claim 5
Dependent Claim
86 words
An automatic diaphragm control device for a TV camera objective according to claim 1, wherein said voltage stabilization means comprises a transistor having a base voltage held at a constant level under action of a resistor, a capacitor and a Zener diode and outputs at its emitter a voltage supplied from a power supply terminal to its collector which is stabilized at a constant level; wherein said constant voltage outputted at the emitter is supplied to the first and second adjustment means and the control means.
Claim 6
Dependent Claim
79 words
An automatic diaphragm control device for a TV camera objective according to claim 1, wherein the control means comprises an operational amplifier for amplifying a multiplied and rectified signal based on adjusted signals from the first and second adjustment means and said feedback signal from said detecting coil in order to provide a control signal, and a Darlington transistor connection consisting of two transistors for supplying said control signal to said driving coil as an extremely high driving voltage.
Claim 7
Dependent Claim
70 words
An automatic diaphragm control device for a TV camera objective according to claim 1, wherein the voltage supply means functions to supply operational amplifiers respectively used in the first and second adjustment means and control means with a mid-range voltage intermediate of said source voltage stabilized by the voltage stabilization means as a reference voltage so that both diaphragm driving and diaphragm control can be achieved with a single source.
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) | 1991-04-12 | 1991-10-12 | 1992-04-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-04-12 | 1995-10-12 | 1996-04-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-04-12 | 1999-10-12 | 2000-04-12 | $7700.00 | Window Closed / Lapsed |