US4302089A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Reflecting mirror device in a single lens reflex camera
Assignee: Nikon Corp
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Filing: 1979-10-15
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Granted: 1981-11-24
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Expires: 1999-10-15
Abstract
Abstract This specification discloses a reflecting mirror device in a single lens reflex camera for receiving light passed through the picture-taking lens of the camera during finder observation, the reflecting mirror device reflecting said light and directing it to a finder optical system, while, at the same time, passing therethrough part of said light and directing it to the light-receiving portion of a metering system. The reflecting mirror device has a number of pin-holes irregularly arranged on the reflecting surface thereof.
Inventors
- 👤 Toru Fukuhara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 13:09
CPC Classifications
G; G03; G03B; G03B19/00; G03B19/02; G03B19/12
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
143 words
A reflecting mirror device in a single lens reflex camera for receiving light passed through the picture-taking lens of the camera during finder observation, said reflecting mirror device reflecting said light and directing it to a finder optical system such as a finder screen while, at the same time, passing therethrough part of said light and directing it to the light-receiving portion of a metering system, said reflecting mirror device having a number of pin-holes irregularly arranged on the reflecting surface thereof, each of said pin-holes having a cross sectional area of the order of 8×10 -5 -8×10 -3 mm 2 whereby it is minute enough so that it is not recognized as a shadow in a finder image and large enough so that the phenomenon of light diffraction created by each pin-hole is not recognized as a flare in the finder image.
Claim 2
Dependent Claim
143 words
A reflecting mirror device in a single lens reflex camera for receiving light passed through the picture-taking lens of the camera during finder observation, said reflecting mirror device reflecting said light and directing it to a finder optical system such as a finder screen while, at the same time, passing therethrough part of said light and directing it to the light-receiving portion of a metering system, said reflecting mirror device having a number of pin-holes irregularly arranged on the reflecting surface thereof, each of said pin-holes having a cross sectional area of the order of 8×10 -5 -8×10 -3 mm 2 whereby it is minute enough so that it is not recognized as a shadow in a finder image and large enough so that the phenomenon of light diffraction created by each pin-hole is not recognized as a flare in the finder image.
Claim 3
Dependent Claim
27 words
The device according to claim 1, wherein the cross-sectional shape of each of said pin-holes is circular and the diameter thereof is several hundredths of one millimeter.
Claim 4
Dependent Claim
31 words
The device according to claim 1, wherein each of said pin-holes is formed so that the shadow thereof in the direction of the optic axis of the picture-taking lens is circular.
Claim 5
Dependent Claim
43 words
The device according to claim 1, wherein the size of each of said pin-holes is determined as a function of the distance between respective pin-holes and the finder screen and is larger as the distance from said pin-hole to said finder screen increases.
Claim 6
Dependent Claim
30 words
The device according to claim 1, wherein said pin-holes are constructed so that the number and size thereof satisfy the desired transmittivity and reflection factor of said reflecting mirror device.
Claim 7
Dependent Claim
44 words
The device according to claim 1, wherein said pin-holes are also provided at a position whereat a diffracted light resulting from the light emergent from the marginal portion of an exit pupil of small F-number having passed through said pin-holes enters said metering system.
Claim 8
Dependent Claim
14 words
The device according to claim 6, wherein said F-number is no greater than F/2.8.
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) | 1984-11-23 | 1985-05-25 | 1985-11-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-11-23 | 1989-05-25 | 1989-11-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-11-23 | 1993-05-25 | 1993-11-24 | $7700.00 | Window Closed / Lapsed |