US4171890A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dichroic rangefinder
Assignee: OSAWA SEIMITSU KOGYO (OSAWA PRECISION INDUSTRIES LTD) KK
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Filing: 1977-12-27
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Granted: 1979-10-23
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Expires: 1997-12-27
Abstract
Abstract Disclosed is a reflex rangefinder system for a camera having a pair of li reflecting members mounted to reflect light rays from the scene in the viewfinder system. The members are dichroically coated with different complementary colors such that the dual image formed when the objective lens is out of focus have different colors to enhance the distinction for easy focusing.
Inventors
- 👤 Yoshiaki Mizuki
- 👤 Michiharu Suwa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 14:58
CPC Classifications
G; G03; G03B; G03B13/00; G03B13/02; G03B13/06; G03B13/08; G03B13/18; G03B13/20
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
198 words
In a camera having first and second lens elements having a common optical axis defining an optical path therebetween, the first lens element transmitting light rays along the optical path, a rangefinder system to facilitate focusing of said camera on a subject and comprising first dichroic reflecting means mounted in the optical path between the lens elements on one side of the optical axis for intercepting a portion of the light rays and reflecting in a predetermined direction only those light rays with a wave length greater than a predetermined value; second dichroic reflecting means mounted in said optical path between the lens elements on the other side of the optical axis for intercepting another portion of the light rays and reflecting in a predetermined direction only those light rays with a wave length less than about the predetermined value; and an optical system arranged to receive the light rays reflected by said first and second dichroic reflecting means to form a superimposed, naturally colored image in a predetermined plane when the camera is in focus on a subject, and to form separate, differently colored images in said plane when the camera is not focused on the subject.
Claim 2
Dependent Claim
198 words
In a camera having first and second lens elements having a common optical axis defining an optical path therebetween, the first lens element transmitting light rays along the optical path, a rangefinder system to facilitate focusing of said camera on a subject and comprising first dichroic reflecting means mounted in the optical path between the lens elements on one side of the optical axis for intercepting a portion of the light rays and reflecting in a predetermined direction only those light rays with a wave length greater than a predetermined value; second dichroic reflecting means mounted in said optical path between the lens elements on the other side of the optical axis for intercepting another portion of the light rays and reflecting in a predetermined direction only those light rays with a wave length less than about the predetermined value; and an optical system arranged to receive the light rays reflected by said first and second dichroic reflecting means to form a superimposed, naturally colored image in a predetermined plane when the camera is in focus on a subject, and to form separate, differently colored images in said plane when the camera is not focused on the subject.
Claim 3
Dependent Claim
14 words
In the camera of claim 1, wherein said predetermined wave length is 500 millimicrons.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-10-22 | 1983-04-23 | 1983-10-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-10-22 | 1987-04-23 | 1987-10-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-10-22 | 1991-04-23 | 1991-10-23 | $7700.00 | Window Closed / Lapsed |