Patent US4750477A successfully refreshed from Google Patents.
US4100407A
Expired / Lapsed
US
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Photoelectric conversion circuit
Assignee: NEC Corp
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Filing: 1977-06-24
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Granted: 1978-07-11
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Expires: 1997-06-24
Abstract
Abstract A novel form of photoelectric conversion circuit including a photo sensor is provided, which is very limited in response time even at low illuminations and highly valuable for use in automatic cameras. It comprises a comparator for comparing the output voltage of the operational amplifier, connected to the photo sensor, with a reference voltage, and discharging means operable under the control of the comparator quickly to discharge the charge stored in a parastic capacitor of the photo sensor when the circuit is energized for operation.
Inventors
- 👤 Akinori Takahashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 17:12
CPC Classifications
G; G01; G01J; G01J1/00; G01J1/42; G01J1/44
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
99 words
A photoelectric conversion circuit comprising a light-receiving element having a parasitic capacitance and producing a signal corresponding to the illumination given thereto, an amplifier having a first and a second terminal connected to the respective terminals of said light-receiving element and producing upon reception of the output signal of said light-receiving element an output voltage corresponding to said output signal, a comparator for comparing the output voltage of said amplifier with a reference voltage, and means for discharging an electric charge stored in said parasitic capacitance of said light-receiving element under the control of the output of said comparator.
Claim 2
Dependent Claim
99 words
A photoelectric conversion circuit comprising a light-receiving element having a parasitic capacitance and producing a signal corresponding to the illumination given thereto, an amplifier having a first and a second terminal connected to the respective terminals of said light-receiving element and producing upon reception of the output signal of said light-receiving element an output voltage corresponding to said output signal, a comparator for comparing the output voltage of said amplifier with a reference voltage, and means for discharging an electric charge stored in said parasitic capacitance of said light-receiving element under the control of the output of said comparator.
Claim 3
Dependent Claim
48 words
The photoelectric conversion circuit of claim 1, wherein said discharging means comprises a bipolar transistor, a collector thereof being connected to one terminal of said light-receiving element, an emitter thereof being connected to the common potential, and a base thereof being connected to the output of said comparator.
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) | 1981-07-10 | 1982-01-09 | 1982-07-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-07-10 | 1986-01-09 | 1986-07-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-07-10 | 1990-01-09 | 1990-07-11 | $7700.00 | Window Closed / Lapsed |