US3827066A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Memory type exposure control system
Assignee: Canon Inc
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Filing: 1973-06-05
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Granted: 1974-07-30
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Expires: 1993-06-05
Abstract
Abstract A memory type exposure control system for controlling the shutter speed of a camera wherein an electrical change of a photovoltaic element on which the light from a scene being photographed impinges through the photographic objective of the camera is amplified by an amplifier circuit and is memorized by a memory condenser in the form of a voltage, and the memorized voltage is applied to a field effect transistor of which the output resistance effected thereby is combined with another condenser to constitute a shutter speed controlling-RC timing circuit whereby the delay time determines the duration of shutter control pulse, an improvement being effected in the sensor circuit so that the memory type exposure control system is made sufficiently responsive to a wider range of incident light intensity than was ever possible.
Inventors
- 👤 T Yanagisawa
- 👤 K Tanikoshi
- 👤 Y Ono
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 13:00
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G03B7/083; G03B7/091; G03B7/093
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
185 words
A memory type exposure control system comprising: a photovoltaic element on which the light from a scene being photographed is incident through the photographic objective of a camera, an amplifier means having input and output terminals to which said photovoltaic element is connected at said input terminal to amplify the electrical output of said element, a memory means for memorizing the electrical output of said photovoltaic element through said amplifier means, said means being connected to the output terminal of the amplifier means, a regenerator means for regenerating a level corresponding to the memorized level of said memory means, said means having input and output terminals, a differential amplifier means connected between said memory means and said regenerator means whereby the regenerated level being put in comparison with the memorized level, a timing circuit for controlling the shutter speed comprising a condenser connected to the output terminal of said regenerator means, and a switching circuit of a certain threshold for detecting the terminal voltage of said condenser, said regenerated output level being altered as acting as a resistance element of a RC time constant circuit.
Claim 2
Dependent Claim
185 words
A memory type exposure control system comprising: a photovoltaic element on which the light from a scene being photographed is incident through the photographic objective of a camera, an amplifier means having input and output terminals to which said photovoltaic element is connected at said input terminal to amplify the electrical output of said element, a memory means for memorizing the electrical output of said photovoltaic element through said amplifier means, said means being connected to the output terminal of the amplifier means, a regenerator means for regenerating a level corresponding to the memorized level of said memory means, said means having input and output terminals, a differential amplifier means connected between said memory means and said regenerator means whereby the regenerated level being put in comparison with the memorized level, a timing circuit for controlling the shutter speed comprising a condenser connected to the output terminal of said regenerator means, and a switching circuit of a certain threshold for detecting the terminal voltage of said condenser, said regenerated output level being altered as acting as a resistance element of a RC time constant circuit.
Claim 3
Dependent Claim
44 words
The memory type exposure control system described in claim 1, wherein said memory means being connected in parallel with said amplifier means, and being provided with a switch means which when turned off permits the memorized level of the amplifier means to be held.
Claim 4
Dependent Claim
29 words
The memory type exposure control system described in claim 1 wherein said photovoltaic element being connected between the base and collector of a transistor used as the amplifier means.
Claim 5
Dependent Claim
29 words
The memory type exposure control system described in claim 1, wherein a log-diode being connected to the output of the amplifier means and in parallel with said memory means.
Claim 6
Dependent Claim
43 words
The memory type exposure control system described in claim 1, wherein a change over switch means being arranged in such a way that said log-diode can be connected by the changeover switch means either into the amplifier means or to the regenerator means.
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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) | 1977-07-29 | 1978-01-28 | 1978-07-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-07-29 | 1982-01-28 | 1982-07-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-07-29 | 1986-01-28 | 1986-07-30 | $7700.00 | Window Closed / Lapsed |