US3657985A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Single lens reflex camera
Assignee: Pentax Corp
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Filing: 1969-12-03
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Granted: 1972-04-25
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Expires: 1989-12-03
Abstract
Abstract A system for observing through the viewfinder, indicia located on the lens barrel of a single lens reflex camera, comprises a window on the pentaprism housing front wall and a second prism positioned along the pentaprism front face and including a first reflector surface proximate the top of said front face and aligned with the indicia and window, and a second reflector surface proximate the bottom of said front face. Light from the indicia incident on the first reflector surface is directed by the second prism through the pentaprism along a path proximate the pentaprism bottom face to the bottom of the viewfinder eyepiece field of view. A lens registers with the window and is followed by a polarizer filter for blocking horizontally polarized light.
Inventors
- 👤 Naoyuki Uno
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 08:47
CPC Classifications
G; G03; G03B; G03B19/00; G03B19/02; G03B19/12; G03B17/00; G03B17/18; G03B17/20
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
206 words
In a single lens reflex camera comprising an objective lens including a barrel, a viewing system including a pentaprism having a bottom first face exposed to light traversing said objective lens, a front, internal, view reflecting second face, and a rear viewing third face, and an eyepiece exposed to light from said third face, and indicia carried by said camera forward of said pentaprism, the improvement comprising means housing said pentaprism and having a front window therein, a positive horizontal cylindrical lens registering with said window and means for directing light from said indicia through said cylindrical lens said pentaprism and said third face into the angle of view of said eyepiece and including a first reflector positioned forward of and adjacent to the upper part of said pentaprism second face and a second reflector positioned forward of and adjacent to the lower part of said pentaprism second face, said first reflector being inclined to reflect light rays from said indicia through said window downwardly along a path substantially parallel to said pentaprism second face to said second reflector, and said second reflector being inclined to reflect said indicia light rays from said first reflector along a path rearwardly through said prism to said third face.
Claim 2
Dependent Claim
206 words
In a single lens reflex camera comprising an objective lens including a barrel, a viewing system including a pentaprism having a bottom first face exposed to light traversing said objective lens, a front, internal, view reflecting second face, and a rear viewing third face, and an eyepiece exposed to light from said third face, and indicia carried by said camera forward of said pentaprism, the improvement comprising means housing said pentaprism and having a front window therein, a positive horizontal cylindrical lens registering with said window and means for directing light from said indicia through said cylindrical lens said pentaprism and said third face into the angle of view of said eyepiece and including a first reflector positioned forward of and adjacent to the upper part of said pentaprism second face and a second reflector positioned forward of and adjacent to the lower part of said pentaprism second face, said first reflector being inclined to reflect light rays from said indicia through said window downwardly along a path substantially parallel to said pentaprism second face to said second reflector, and said second reflector being inclined to reflect said indicia light rays from said first reflector along a path rearwardly through said prism to said third face.
Claim 3
Dependent Claim
14 words
The camera of claim 1 wherein said indicia are positioned on said lens barrel.
Claim 4
Dependent Claim
30 words
The camera of claim 1 wherein said light directing means directs said lighT from said indicia along a path through said pentaprism substantially parallel to and proximate said first face.
Claim 5
Dependent Claim
26 words
The camera of claim 1 wherein said first and second reflectors are defined by the upper and lower inclined faces of an internally reflecting prism member.
Claim 6
Dependent Claim
21 words
The camera of claim 1 including a polarizing filter located in the path of light between said indicia and said pentaprism.
Claim 7
Dependent Claim
28 words
The camera of claim 1 including a polarizing filter located in the path of light between said indicia and said eyepiece and oriented to block horizontally polarized light.
Claim 8
Dependent Claim
36 words
The camera of claim 1 wherein said housing includes a front wall positioned forwardly of said pentaprism second face and said first and second reflectors are disposed between said front wall and said pentaprism second face.
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) | 1975-04-25 | 1975-10-25 | 1976-04-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-25 | 1979-10-25 | 1980-04-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-25 | 1983-10-25 | 1984-04-25 | $7700.00 | Window Closed / Lapsed |