US3885880A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Light sensing device with auxiliary illumination
Assignee: Canon Inc
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Filing: 1973-11-07
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Granted: 1975-05-27
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Expires: 1993-11-07
Abstract
Abstract The light sensing device includes a diode having a logarithmic compression characteristics, or a circuit with compression characteristics, and a light receiving element to receive light from an object. An irradiating element provides auxiliary illumination, at an early state of light sensing, at the light receiving plane of the light receiving element, so that the delay in response, caused by the compression characteristics element in the light sensing circuit and by other elements within the light sensing circuit, is compensated by exciting the irradiating element.
Inventors
- 👤 Tokuichi Tsunekawa
- 👤 Soichi Nakamoto
- 👤 Tetsuya Taguchi
- 👤 Takehiko Kiyohara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 14:09
CPC Classifications
G; G01; G01J; G01J1/00; G01J1/42; G01J1/44; G03; G03B; G03B19/00; G03B19/02; G03B19/12
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
134 words
A light sensing device comprising, in combination, a photovoltaic cell generating an electric signal proportional to the light intensity incident thereupon, and having an output; a direct current operational amplifier having an input connected to the output of said cell and having an output; a source of d.c. potential; switch means selectively operable to connect said source to said amplifier to provide an operating potential thereto to initiate a light sensing operation; indicating means connected to the output of said amplifier to indicate a light value responsive to the amplified electric output signal of said cell; irradiating means operable, when energized, to emit light incident upon said cell; and means operable, upon initiation of a light sensing operation, to connect said irradiating means to said source for at least momentarily energizing said irradiating means.
Claim 2
Dependent Claim
134 words
A light sensing device comprising, in combination, a photovoltaic cell generating an electric signal proportional to the light intensity incident thereupon, and having an output; a direct current operational amplifier having an input connected to the output of said cell and having an output; a source of d.c. potential; switch means selectively operable to connect said source to said amplifier to provide an operating potential thereto to initiate a light sensing operation; indicating means connected to the output of said amplifier to indicate a light value responsive to the amplified electric output signal of said cell; irradiating means operable, when energized, to emit light incident upon said cell; and means operable, upon initiation of a light sensing operation, to connect said irradiating means to said source for at least momentarily energizing said irradiating means.
Claim 3
Dependent Claim
39 words
A light sensing device, as claimed in claim 1, comprising a first feedback loop, including said amplifier, effecting logarithmic transformation of the output signal of said cell and relating the amplifier output signal proportionately to a diode generated signal.
Claim 4
Dependent Claim
18 words
A light sensitive device, as claimed in claim 1, in which said cell is a silicon blue cell.
Claim 5
Dependent Claim
17 words
A light sensing device, as claimed in claim 2, wherein said first feedback loop includes a diode.
Claim 6
Dependent Claim
26 words
A light sensing device, as claimed in claim 2, comprising a second feedback loop including said amplifier; and a capacitor included in said second feedback loop.
Claim 7
Dependent Claim
58 words
A light sensing device, as claimed in claim 1, including a semi-transparent mirror positioned adjacent said cell, light from a scene being incident upon said cell through said semi-transparent mirror; said irradiating means comprising a light source positioned adjacent said semi-transparent mirror, and a light from said light source being reflected to said cell by said semi-transparent mirror.
Claim 8
Dependent Claim
29 words
A light sensing device, as claimed in claiM 1, including a diode and a condensor connected, in parallel with each other, between the input and output of said amplifier.
Claim 9
Dependent Claim
34 words
A light sensing device, as claimed in claim 1, in which said switch means comprises a main switch; said means operable to connect said irradiating means to said source comprising an instantaneously operable switch.
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) | 1978-05-26 | 1978-11-25 | 1979-05-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-26 | 1982-11-25 | 1983-05-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-26 | 1986-11-25 | 1987-05-27 | $7700.00 | Window Closed / Lapsed |