Patent US3936849A successfully refreshed from Google Patents.
US3936849A
Expired / Lapsed
US
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Device for detecting focussing in optical instruments
Assignee: Minolta Co Ltd
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Filing: 1974-08-08
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Granted: 1975-02-03
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Expires: 1994-08-08
Abstract
Abstract A device for detecting focussing in an optical instrument such as a camera which has an objective lens and a plane, at which light sensitive film may be disposed, upon which a real image of an object is intended to be focussed. The device comprises a window to which the eye of the operator is held, and means for projecting light to the operator's eye which looks at the real image of the object formed by the objective lens. The light projected on the retina of the operator's eye is reflected back into the camera and is directed to focus-judging means in the nature of a light sensitive member which detects when the retina of the operator's eye is optically conjugate with an imaginary reference plane located in a position optically equal to a plane on which a real image of the object formed by the objective lens is intended to be focussed, thus also detecting when the position of the real image coincides with said reference plane so that the selected object is properly focussed.
Inventors
- 👤 Kayoshi Tsujimoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 10:57
CPC Classifications
G; G03; G03B; G03B3/00; G02; G02B; G02B7/00; G02B7/28; G02B7/36
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
138 words
In an optical instrument, a device for detecting focussing conditions comprising: an objective lens; an imaginary reference plane predetermined at a position optically equal to a plane on which a real image of an object formed by said objective lens is intended to be focussed; means for adjusting said objective lens to shift said real image from positions forwardly and rewardly of said reference plane; a viewing window positioned to permit the eye of an operator of the instrument to view said real image there through; and means for detecting that said reference plane and the retina of said eye of the operator are optically conjugate to each other with respect to the crystalline lens of said eye which views said real image, whereby indirectly detecting that the position of said real image coincides with said reference plane.
Claim 2
Dependent Claim
138 words
In an optical instrument, a device for detecting focussing conditions comprising: an objective lens; an imaginary reference plane predetermined at a position optically equal to a plane on which a real image of an object formed by said objective lens is intended to be focussed; means for adjusting said objective lens to shift said real image from positions forwardly and rewardly of said reference plane; a viewing window positioned to permit the eye of an operator of the instrument to view said real image there through; and means for detecting that said reference plane and the retina of said eye of the operator are optically conjugate to each other with respect to the crystalline lens of said eye which views said real image, whereby indirectly detecting that the position of said real image coincides with said reference plane.
Claim 3
Dependent Claim
106 words
A device as in claim 1, wherein said detecting means comprises: means for projecting light rays of a predetermined range of wave length from at least one small area of said reference plane into the eye of the operator; means for receiving the light rays deflected from said retina at a position optically equal to said small area; and means for producing an output corresponding to the amount of light received by said receiving means, whereby said output producing means presents the maximum output when said reference plane and the retina are optically conjugate to each other with respect to the crystalline lens of said eye.
Claim 4
Dependent Claim
167 words
A device as in claim 2, wherein: said projecting means comprises a first filter disposed at said reference plane and adapted to selectively filter out light rays of said predetermined range of wave length coming from an objective field, said first filter being provided with at least one small area allowing the passage of light rays of said predetermined range of wave length; and said receiving means comprises a semi-transparent mirror disposed between said first filter and said viewing window for deflecting the light rays coming from the retina, a light shielding plate with an opening located and shaped symmetrically to said small area with respect to said semi-transparent mirror for receiving the light rays deflected by said semi-transparent mirror at said opening, a light sensitive member disposed behind said opening and connected to said output producing means, and a second filter disposed between said semi-transparent mirror and said light sensitive member and adapted to filter out light rays of wave lengths outside of said predetermined range.
Claim 5
Dependent Claim
143 words
A device as in claim 2, wherein: said projecting means comprises a first filter disposed at said reference plane and adapted to selectively filter out light rays of said predetermined range of wave length, said filter being provided with at least one small area allowing the passage of light rays of said predetermined range of wave length, light source means for projecting light rays of said predetermined range of wave length into the eye of the operator through said small area; and said receiving means comprises a light sensitive member connected to said producing means, means for guiding the light rays coming from the retina through said small area to said light sensitive member, and a second filter disposed between said guiding means and said light sensitive member and adapted to filter out light rays of wave lengths outside of said predetermined range.
Claim 6
Dependent Claim
91 words
A device as in claim 4, wherein said reference plane is determined outside of the path of light rays passed through said objective lens, and said device further comprises a mirror disposed in said path of the light rays which direct said real image toward said reference plane, and a light sensitive film disposed symmetrically to said reference plane with respect to said mirror, said mirror being further movable to retract out of said path of light rays for allowing said real image to be focussed on said light sensitive film.
Claim 7
Dependent Claim
176 words
A device as in claim 1, wherein said detecting means comprises: a first filter disposed at said reference plane and provided with at least one small area having the characteristic of selectively cutting off light rays of said predetermined range of wave length coming from an objective field: a semi-transparent mirror disposed between said first filter and said viewing window for deflecting the light rays coming from the retina; a light shielding plate with an opening located and shaped symmetrically to said small area with respect to said semi-transparent mirror for receiving the light rays deflected by said semi-transparent mirror at said opening; a light sensitive member disposed behind said opening and connected to said producing means; and a second filter disposed between said semi-transparent mirror and said light sensitive member and adapted to filter out light rays of wave lengths outside of said predetermined range. whereby said producing means presents the minimum output when said reference plane and the retina are optically conjugate to each other with respect to the crystalline lens of said eye.
Claim 8
Dependent Claim
82 words
A device as in claim 6, further comprising a inverting lens for forming a secondary real image of said object, and wherein said viewing window is disposed for the eye of the operator to view said secondary real image and for said light rays from the objective field to travel into the eye through said first filter, said semi-transparent mirror and said inverting lens, whereby said detecting means detects said conjugation between said reference plane and the retina through said inverting lens.
Claim 9
Dependent Claim
95 words
A device as in claim 6, wherein said reference plane is determined outside of the path of light rays passed through said objective lens, and said device further comprises a second semi-transparent mirror disposed in said objective lens for directing said real image toward said reference plane, a light sensitive film disposed in said path of light rays, and a compensating lens disposed between said second semi-transparent mirror and said reference plane for optically setting said reference plane at a position optically equal to said light sensitive film with respect to said second semi-transparent mirror.
Claim 10
Dependent Claim
34 words
A device as in claim 1, further comprising an ocular lens disposed at said viewing window, whereby said detecting means detects said conjugation between said reference plane and the retina through said ocular lens.
Claim 11
Dependent Claim
63 words
A device as in claim 1, wherein said detecting means comprises a light receiving plane disposed at a position optically equal to said reference plane so as to be projected with a real image of the retina formed by the crystalline lens of said eye, and means for judging that said real image of the retina is focussed on said light receiving plane.
Claim 12
Dependent Claim
54 words
A device as in claim 10, wherein said detecting means further comprises means for illuminating the retina with light rays of said predetermined range of wave length, and a filter disposed in front of said light receiving plane and being adapted to filter out light rays of wave lengths outside of said predetermined range.
Claim 13
Dependent Claim
56 words
A device as in claim 10, wherein said light receiving plane is located outside of the path of light rays defined between said reference plane and the retina, and said detecting means further comprises a semi-transparent mirror disposed in said path of light for introducing light rays coming from said retina to said light receiving plane.
Claim 14
Dependent Claim
47 words
A device as in claim 12, wherein said detecting means further comprises a compensating lens disposed between said semi-transparent mirror and said light receiving plane for optically setting said light receiving plane at a position optically equal to said reference plane with respect to said semi-transparent mirror.
Claim 15
Dependent Claim
48 words
A device as in claim 1, further comprising means for automatically controlling said adjusting means, said controlling means being so related to said detecting means as to stop said shift of the real image when said detecting means detects said conjugation between said reference plane and the retina.
References Cited (Backward Citations)
US3543666A
Cited
US3713371A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-02-02 | 1978-08-04 | 1979-02-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-02 | 1982-08-04 | 1983-02-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-02 | 1986-08-04 | 1987-02-03 | $7700.00 | Window Closed / Lapsed |