US4652109A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Camera light measuring system with aperture correction for different measuring modes
Assignee: Canon Inc
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Filing: 1985-05-15
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Granted: 1987-03-24
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Expires: 2005-05-15
Abstract
Abstract In the disclosed system shifting light-measuring modes are shifted by restricting the view angle of a light sensitive element or by producing differences between a first light measuring circuit and a second light measuring circuit, each having a different light measuring range. A correction circuit determines aperture corrections for mode changes. When the exposure is controlled, the output of the light measurement is corrected by the output of the correction circuit.
Inventors
- 👤 Tokuichi Tsunekawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 16:45
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G03B7/087
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
204 words
A light measuring system for a camera, including: (a) first light measuring means for measuring light passing through an objective lens having an aperture and for producing an electrical signal representing the brightness of a portion of an object to be photographed; (b) a second light measuring means for measuring light entering through said objective lens and for producing electrical signals representing the brightness of a portion of the object different from the portion for said first light measuring means; (c) first computing means for computing the output of said first light measuring means and the output of said second light measuring means and for producing an electrical signal representing the computed value; (d) correcting means responsive to the difference between the output of said first computing means and the output of said first light measuring means for correcting information concerning the aperture of the objective lens on the basis of the difference, said means being arranged for producing an electrical signal representing a corrected aperture value; and (e) a second computing means for computing the output signal of said first computing means and the output signal of said correcting means and for producing an electrical signal representing the computed value for exposure control.
Claim 2
Dependent Claim
204 words
A light measuring system for a camera, including: (a) first light measuring means for measuring light passing through an objective lens having an aperture and for producing an electrical signal representing the brightness of a portion of an object to be photographed; (b) a second light measuring means for measuring light entering through said objective lens and for producing electrical signals representing the brightness of a portion of the object different from the portion for said first light measuring means; (c) first computing means for computing the output of said first light measuring means and the output of said second light measuring means and for producing an electrical signal representing the computed value; (d) correcting means responsive to the difference between the output of said first computing means and the output of said first light measuring means for correcting information concerning the aperture of the objective lens on the basis of the difference, said means being arranged for producing an electrical signal representing a corrected aperture value; and (e) a second computing means for computing the output signal of said first computing means and the output signal of said correcting means and for producing an electrical signal representing the computed value for exposure control.
Claim 3
Dependent Claim
53 words
A system as in claim 1, wherein said first light measuring means has a photosensitive element for sensing the brightness of an object of principal photographic interest, and said second light measuring means has a plurality of photosensitive elements for sensing the brightnesses of respective different portions of the environment surrounding said object.
Claim 4
Dependent Claim
214 words
A light measuring system for a camera, including: (a) first light measuring means for measuring light passing through an objective lens having an aperture and for producing an electrical signal representing the brightness of a portion of an object to be photographed; (b) second light measuring means for measuring light entering said objective lens and for producing electrical signals representing the brightness of portions of the object different from the portion of said first light measuring means; (c) first computing means for computing the output of said first light measuring means and the output of said second light measuring means and for producing an electrical signal representing the computed value; (d) means for generating aperture information on the basis of said aperture of the objective lens; (e) correcting means responsive to the difference between the output of said first computing means and the output of said first light measuring means for correcting the aperture information of the objective lens on the basis of the difference, said means being arranged for producing an electrical signal representing the corrected value, and (f) second computing means for computing the output signal of said first computing means and the output signal of said correcting means and for producing an electrical signal representing the computed value for exposure control.
Claim 5
Dependent Claim
214 words
A light measuring system for a camera, including: (a) first light measuring means for measuring light passing through an objective lens having an aperture and for producing an electrical signal representing the brightness of a portion of an object to be photographed; (b) second light measuring means for measuring light entering said objective lens and for producing electrical signals representing the brightness of portions of the object different from the portion of said first light measuring means; (c) first computing means for computing the output of said first light measuring means and the output of said second light measuring means and for producing an electrical signal representing the computed value; (d) means for generating aperture information on the basis of said aperture of the objective lens; (e) correcting means responsive to the difference between the output of said first computing means and the output of said first light measuring means for correcting the aperture information of the objective lens on the basis of the difference, said means being arranged for producing an electrical signal representing the corrected value, and (f) second computing means for computing the output signal of said first computing means and the output signal of said correcting means and for producing an electrical signal representing the computed value for exposure control.
Claim 6
Dependent Claim
54 words
A system as described in claim 3, wherein said first light measuring means has a photosensitive element for sensing the brightness of an object of principal photographic interest, and said second light measuring means has a plurality of photosensitive elements for sensing the brightness of respective different portions of the environment surrounding said object.
Claim 7
Dependent Claim
231 words
A light measuring system for a camera, including: (a) first light measuring means for measuring light passing through an objective lens and for sensing the brightness of an object of principal photographic interest, and for producing an electrical signal representing the brightness of a portion of the object to be photographed; (b) second light measuring means for measuring light entering the objective lens and for producing electrical signals representing the brightnesses of the portion of the object to be photographed; (c) first computing means for computing the difference between the output of said first light measuring means and the output of said second light measuring means and for producing an electrical signal representing the computed value; (d) aperture information generating means for generating an electrical signal corresponding to the full-open F-number signal of the objective lens; (e) correcting means responsive to the difference between the output of said first light measuring means and the output of said second light measuring means for correcting the aperture information of the objective lens on the basis of the difference, said means being arranged for producing an electrical signal representing the corrected value; and (f) second computing means for computing the output signal of said first light measuring means and second light measuring means and the output signal of said correcting means and for producing an electrical signal representing the computed value for exposure control.
Claim 8
Dependent Claim
231 words
A light measuring system for a camera, including: (a) first light measuring means for measuring light passing through an objective lens and for sensing the brightness of an object of principal photographic interest, and for producing an electrical signal representing the brightness of a portion of the object to be photographed; (b) second light measuring means for measuring light entering the objective lens and for producing electrical signals representing the brightnesses of the portion of the object to be photographed; (c) first computing means for computing the difference between the output of said first light measuring means and the output of said second light measuring means and for producing an electrical signal representing the computed value; (d) aperture information generating means for generating an electrical signal corresponding to the full-open F-number signal of the objective lens; (e) correcting means responsive to the difference between the output of said first light measuring means and the output of said second light measuring means for correcting the aperture information of the objective lens on the basis of the difference, said means being arranged for producing an electrical signal representing the corrected value; and (f) second computing means for computing the output signal of said first light measuring means and second light measuring means and the output signal of said correcting means and for producing an electrical signal representing the computed value for exposure control.
Claim 9
Dependent Claim
123 words
A light measuring system for a camera, including: (a) first light measuring means for measuring light passing through an objective lens and for producing an electrical signal representing the brightness of the object; (b) second light measuring means for measuring light passing through the objective lens and for producing an electrical signal representing the brightness of the object, said second light measuring means having a light measuring range different from that of said first light measuring means; and (c) correcting means for producing a correcting signal to correct an aperture correction factor of the objective lens, said correcting means producing said correcting signal in response to the output of said first light measuring means and the output of said second light measuring means.
Claim 10
Dependent Claim
123 words
A light measuring system for a camera, including: (a) first light measuring means for measuring light passing through an objective lens and for producing an electrical signal representing the brightness of the object; (b) second light measuring means for measuring light passing through the objective lens and for producing an electrical signal representing the brightness of the object, said second light measuring means having a light measuring range different from that of said first light measuring means; and (c) correcting means for producing a correcting signal to correct an aperture correction factor of the objective lens, said correcting means producing said correcting signal in response to the output of said first light measuring means and the output of said second light measuring means.
Claim 11
Dependent Claim
33 words
A system according to claim 6, wherein the correcting signal of said correcting means is produced on the basis of the difference between the outputs of said first and second light measuring means.
References Cited (Backward Citations)
US4306787A
Cited
US4420252A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-03-23 | 1990-09-22 | 1991-03-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-03-23 | 1994-09-22 | 1995-03-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-03-23 | 1998-09-22 | 1999-03-24 | $7700.00 | Window Closed / Lapsed |