Patent US4479708A successfully refreshed from Google Patents.
US4479708A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Temperature compensation system of light measuring circuit
Assignee: Canon Inc
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Filing: 1982-06-29
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Granted: 1984-10-30
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Expires: 2002-06-29
Abstract
Abstract Disclosed is a temperature compensation system for light measuring circuits. Said system compensates for the change, over temperature, of the output of the light measuring circuit by applying a bias source with a predetermined temperature coefficient. The system is designed so the bias voltage source is derived from the V BE (base to emitter voltage) difference between a pair of transistors, which difference is generated by the difference of current density at the junction of the pair of transistors obtained by flowing a pair of currents with a constant ratio independent of temperature.
Inventors
- 👤 Ryuji Tokuda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 16:43
CPC Classifications
G; G01; G01J; G01J1/00; G01J1/42; G01J1/44; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G03B7/083; Y; Y10; Y10S; Y10S323/00; Y10S323/907
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
184 words
A temperature compensated exposure control circuit for a camera comprising: (a) a regulator including a portion for generating a first voltage having a characteristic proportional to an absolute temperature derived from differences between current densities of a pair of transistors and another portion for generating a second voltage having a negative thermal coefficient by utilizing the fact that the voltage across the base-emitter path of a transistor has a negative thermal coefficient, said regulator putting out said first voltage proportional to the absolute temperature and a voltage of very small thermal coefficient by adding said first voltage and said second voltage; (b) a photosensitive element; (c) operational amplifier means for amplifying the output of said photosensitive element; (d) means for feeding back the output of said operational amplifier means to an input of said operational amplifier means, said feedback means including a first semiconductor element for compressing the output of said photosensitive element; (e) connection means for connecting said first voltage to a non-inverting input terminal of said operational amplifier; and (f) a second semiconductor element for expanding the output of said operational amplifier.
Claim 2
Dependent Claim
184 words
A temperature compensated exposure control circuit for a camera comprising: (a) a regulator including a portion for generating a first voltage having a characteristic proportional to an absolute temperature derived from differences between current densities of a pair of transistors and another portion for generating a second voltage having a negative thermal coefficient by utilizing the fact that the voltage across the base-emitter path of a transistor has a negative thermal coefficient, said regulator putting out said first voltage proportional to the absolute temperature and a voltage of very small thermal coefficient by adding said first voltage and said second voltage; (b) a photosensitive element; (c) operational amplifier means for amplifying the output of said photosensitive element; (d) means for feeding back the output of said operational amplifier means to an input of said operational amplifier means, said feedback means including a first semiconductor element for compressing the output of said photosensitive element; (e) connection means for connecting said first voltage to a non-inverting input terminal of said operational amplifier; and (f) a second semiconductor element for expanding the output of said operational amplifier.
Claim 3
Dependent Claim
76 words
A temperature compensated exposure circuit for a camera according to claim 1, further comprising: (a) a capacitor for storing the output of said second semiconductor, one pole of said capacitor being connected to the output of very small thermal coefficient of said regulator; and (b) a comparator for comparing a potential of both terminals of said capacitor with a voltage divided with a predetermined ratio of the output of very small thermal coefficient of said regulator.
Claim 4
Dependent Claim
26 words
A temperature compensated exposure control circuit for a camera according to claim 1, in which the connection means includes an amplifying circuit having an appropriate gain.
Claim 5
Dependent Claim
157 words
A temperature compensated exposure control circuit for a camera comprising: (a) a regulator including a portion for generating a first voltage having a characteristic proportional to an absolute temperature and another portion for generating a second voltage having a characteristic of negative thermal coefficient, said regulator producing said first voltage proportional to the absolute temperature and the combined voltage of said first voltage and said second voltage which has a very small thermal coefficient; (b) a photosensitive element; (c) operational amplifier means for amplifying the output of said photosensitive element; (d) means for feeding back the output of said operational amplifier means to an input of said operational amplifier means, said feedback means including a first semiconductor element for compressing the output of said photosensitive element; (e) connection means for connecting said first voltage to a non-inverting output terminal of said operational amplifier; and (f) a second semiconductor element for expanding the output of said operational amplifier.
Claim 6
Dependent Claim
157 words
A temperature compensated exposure control circuit for a camera comprising: (a) a regulator including a portion for generating a first voltage having a characteristic proportional to an absolute temperature and another portion for generating a second voltage having a characteristic of negative thermal coefficient, said regulator producing said first voltage proportional to the absolute temperature and the combined voltage of said first voltage and said second voltage which has a very small thermal coefficient; (b) a photosensitive element; (c) operational amplifier means for amplifying the output of said photosensitive element; (d) means for feeding back the output of said operational amplifier means to an input of said operational amplifier means, said feedback means including a first semiconductor element for compressing the output of said photosensitive element; (e) connection means for connecting said first voltage to a non-inverting output terminal of said operational amplifier; and (f) a second semiconductor element for expanding the output of said operational amplifier.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-10-30 | 1988-04-30 | 1988-10-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-10-30 | 1992-04-30 | 1992-10-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-10-30 | 1996-04-30 | 1996-10-30 | $7700.00 | Window Closed / Lapsed |