US5138358A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Autofocusing apparatus utilizing intermittent light projection
Assignee: Canon Inc
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Filing: 1991-11-12
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Granted: 1992-08-11
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Expires: 2011-11-12
Abstract
Abstract An autofocus apparatus for use with a light projection device which projects light to an object, and a storage sensor which alternately receives light reflected from the object when the light is projected onto the object and when the light is not projected onto the object includes an extraction circuit for extracting from the storage sensor (1) a first sensor output corresponding to when the light is projected onto the object, and (2) a second sensor output corresponding to when the light is not projected onto the object. A setting circuit is provided for setting the sensor in an initial state every time the extraction circuit extracts an output signal from the storage sensor. A control circuit is provided for calculating a difference between the first and second sensor signals and providing an output signal corresponding to the difference.
Inventors
- 👤 Keisuke Aoyama
- 👤 Akira Ishizaki
- 👤 Kenji Suzuki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 12:05
CPC Classifications
G; G02; G02B; G02B7/00; G02B7/28; G02B7/30; G02B7/32
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
261 words
An autofocus apparatus for use with a light projection device which projects light to an object intermittently, comprising: a storage sensor which alternately receives light reflected from the object when the light is projected onto the object and when the light is not projected onto the object; and a processing circuit coupled to said storage sensor for (1) causing said storage sensor to perform a first signal storing operation when the light projection device projects light, (2) for causing said storage sensor to perform a second signal storing operation when the light projection device does not project light, (3) for causing said storage sensor to perform an initial signal storing operation for a time required for a signal storing state of said storage sensor to reach a predetermined value, (4) for causing said storage sensor to perform a subsequent signal storing operation for a time corresponding to the time for the initial signal storing operation, (5) for reading from said storage sensor (a) a first sensor output signal obtained in the first signal storing operation every time the first signal storing operation is completed, and (b) a second sensor output signal obtained in the second signal storing operation every time the second signal storing operation is completed, (6) for setting said storage sensor in an initial state every time an output signal is read from said storage sensor, to cause the sensor to receive light in the initial state, and (7) for calculating a difference between said first and second sensor signals and providing an output signal corresponding to said difference.
Claim 2
Dependent Claim
261 words
An autofocus apparatus for use with a light projection device which projects light to an object intermittently, comprising: a storage sensor which alternately receives light reflected from the object when the light is projected onto the object and when the light is not projected onto the object; and a processing circuit coupled to said storage sensor for (1) causing said storage sensor to perform a first signal storing operation when the light projection device projects light, (2) for causing said storage sensor to perform a second signal storing operation when the light projection device does not project light, (3) for causing said storage sensor to perform an initial signal storing operation for a time required for a signal storing state of said storage sensor to reach a predetermined value, (4) for causing said storage sensor to perform a subsequent signal storing operation for a time corresponding to the time for the initial signal storing operation, (5) for reading from said storage sensor (a) a first sensor output signal obtained in the first signal storing operation every time the first signal storing operation is completed, and (b) a second sensor output signal obtained in the second signal storing operation every time the second signal storing operation is completed, (6) for setting said storage sensor in an initial state every time an output signal is read from said storage sensor, to cause the sensor to receive light in the initial state, and (7) for calculating a difference between said first and second sensor signals and providing an output signal corresponding to said difference.
Claim 3
Dependent Claim
14 words
Apparatus according to claim 1 wherein said autofocus apparatus is incorporated in a camera.
Claim 4
Dependent Claim
15 words
Apparatus according to claim 1 wherein the storage sensor comprises a plurality of picture elements.
Claim 5
Dependent Claim
25 words
Apparatus according to claim 1 wherein said processing circuit includes an A/D conversion circuit for converting analog signals output from said sensor into digital signals.
Claim 6
Dependent Claim
245 words
An autofocus apparatus for use with a light projection device which projects light to an object intermittently, comprising: a storage sensor which alternately receives light reflected from the object when the light is projected onto the object and when the light is not projected onto the object; and a processing circuit coupled to said storage sensor for (1) causing said storage sensor to perform a first signal storing operation when the light projection device projects light, (2) for causing said storage sensor to perform a second signal storing operation when the light projection device does not project light, (3) for reading from said storage sensor (a) a first sensor output signal obtained in the first signal storing operation every time the first signal storing operation is completed, and (b) a second sensor output signal obtained in the second signal storing operation every time the second signal storing operation is completed, (4) for resetting said storage sensor to an initialized state each time a sensor output is read from said storage sensor, to cause said storage sensor to receive light in the initialized state, (5) for calculating a difference between the first and second sensor output signals each time the first and second sensor output signals are read, (6) for providing difference signals corresponding to the calculated differences between the first and second sensor output signals, (7) for adding the provided difference signals, and (8) for focusing an optical system based on the added difference signals.
Claim 7
Dependent Claim
245 words
An autofocus apparatus for use with a light projection device which projects light to an object intermittently, comprising: a storage sensor which alternately receives light reflected from the object when the light is projected onto the object and when the light is not projected onto the object; and a processing circuit coupled to said storage sensor for (1) causing said storage sensor to perform a first signal storing operation when the light projection device projects light, (2) for causing said storage sensor to perform a second signal storing operation when the light projection device does not project light, (3) for reading from said storage sensor (a) a first sensor output signal obtained in the first signal storing operation every time the first signal storing operation is completed, and (b) a second sensor output signal obtained in the second signal storing operation every time the second signal storing operation is completed, (4) for resetting said storage sensor to an initialized state each time a sensor output is read from said storage sensor, to cause said storage sensor to receive light in the initialized state, (5) for calculating a difference between the first and second sensor output signals each time the first and second sensor output signals are read, (6) for providing difference signals corresponding to the calculated differences between the first and second sensor output signals, (7) for adding the provided difference signals, and (8) for focusing an optical system based on the added difference signals.
Claim 8
Dependent Claim
14 words
Apparatus according to claim 5 wherein said autofocus apparatus is incorporated in a camera.
Claim 9
Dependent Claim
25 words
Apparatus according to claim 5 wherein said processing circuit determines a number of addition operations carried out in the adding of the provided different signals.
Claim 10
Dependent Claim
27 words
Apparatus according to claim 5 wherein said processing circuit determines when a difference between a maximum difference signal and a minimum difference signal exceeds a predetermined threshold.
Claim 11
Dependent Claim
15 words
Apparatus according to claim 5 wherein the storage sensor comprises a plurality of picture elements.
Claim 12
Dependent Claim
25 words
Apparatus according to claim 5 wherein said processing circuit includes an A/D conversion circuit for converting analog signals output from said sensor into digital signals.
References Cited (Backward Citations)
JPS55118019A
Cited
JPS55155331A
Cited
US4681432A
Cited
US4701626A
Cited
US4678323A
Cited
US4835561A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-08-11 | 1996-02-10 | 1996-08-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-08-11 | 2000-02-10 | 2000-08-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-08-11 | 2004-02-10 | 2004-08-11 | $7700.00 | Window Closed / Lapsed |