Patent US3823318A successfully refreshed from Google Patents.
US3823318A
Expired / Lapsed
US
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Circuit arrangement for exposure measuring devices
Assignee: Siemens AG
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Filing: 1973-01-10
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Granted: 1974-07-09
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Expires: 1993-01-10
Abstract
Abstract Circuit arrangement for exposure measuring devices with a light detector operating as a photo element and measuring light conditions, which element is switched on at the initiation of a light measurement and operates into a load as well as an amplifier with a high-pass characteristic.
Inventors
- 👤 G Krause
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 12:34
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G01; G01J; G01J1/00; G01J1/42; G01J1/44
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
113 words
A circuit arrangement for exposure measuring devices of the type used in an exposure meter or in an automatic exposure device for a camera, comprising: a light sensitive device operable as a photo electric element; switching means for connecting said ligHt sensitive device in a closed current path at the initiation of a light measurement; an amplifier circuit having an input and an output, said light sensitive device connected to said input of said amplifier circuit; and a load path connected to said light sensitive device and to said output, said amplifier circuit having a high-pass characteristic having a boundary frequency that is inversely proportional to the longest exposure time to be measured.
Claim 2
Dependent Claim
113 words
A circuit arrangement for exposure measuring devices of the type used in an exposure meter or in an automatic exposure device for a camera, comprising: a light sensitive device operable as a photo electric element; switching means for connecting said ligHt sensitive device in a closed current path at the initiation of a light measurement; an amplifier circuit having an input and an output, said light sensitive device connected to said input of said amplifier circuit; and a load path connected to said light sensitive device and to said output, said amplifier circuit having a high-pass characteristic having a boundary frequency that is inversely proportional to the longest exposure time to be measured.
Claim 3
Dependent Claim
28 words
A circuit arrangement according to claim 1, wherein said switching means includes contacts connected to normally short circuit said light sensitive device until immediately prior to a measurement.
Claim 4
Dependent Claim
29 words
A circuit arrangement according to claim 1, wherein said switching means includes contacts operated to connect said light sensitive device and said amplifier circuit immediately prior to a measurement.
Claim 5
Dependent Claim
14 words
A circuit arrangement according to claim 1, wherein said load path includes a capacitor.
Claim 6
Dependent Claim
14 words
A circuit arrangement according to claim 1, wherein said load path includes a resistor.
Claim 7
Dependent Claim
60 words
A circuit arrangement according to claim 1, wherein said amplifier circuit includes an operational amplifier having an inverting input, a non-inverting input and an output, a capacitive coupling between said inverting input and said light sensitive device, a negative feedback connection between said output and said inverting input, and a threshold device connected between said output and said non-inverting input.
Claim 8
Dependent Claim
43 words
A circuit arrangement according to claim 1, comprising a field effect transistor having an input electrode connected to said light sensitive device, and an output electrode, and an impedance matching stage coupling said output electrode to said inverting input of said operational amplifier.
Claim 9
Dependent Claim
21 words
A circuit arrangement according to claim 7, comprising an active load connected to said output electrode of said field effect transistor.
Claim 10
Dependent Claim
16 words
A circuit arrangement according to claim 1, wherein said light sensitive device is a photo diode.
Claim 11
Dependent Claim
27 words
A circuit arrangement according to claim 9, wherein said switching means includes contacts connected to normally short circuit said photo diode until immediately prior to a measurement.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-07-08 | 1978-01-07 | 1978-07-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-07-08 | 1982-01-07 | 1982-07-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-07-08 | 1986-01-07 | 1986-07-09 | $7700.00 | Window Closed / Lapsed |