Patent US4021012A successfully refreshed from Google Patents.
US3563149A
Expired / Lapsed
US
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Light-measuring system employing viewer surplus light
Assignee: Pentax Corp
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Filing: 1968-06-06
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Granted: 1971-02-16
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Expires: 1988-06-06
Abstract
Abstract A through the lens light-measuring system includes a lighttransmitting surface at the mirror-reflected focal plane of a reflex camera, a pentaprism having a bottom face confronting the light-transmitting surface, and an eyepiece directed to the prism rear face. Opposite side sections of the prism face are transparent and outside the viewing area of the eyepiece and an upwardly facing photocell is located proximate the bottom edge of each side section and a prism of other reflector directs the image rays reflected from the prism roof through the side sections onto the photocells. One of the photocells is provided with a lens for focusing part of the image. In an alternative form the photocells face the prism rear face on opposite sides of the eyepiece and are oblique to the optical axis to compensate for light intensity differences consequent to differences in angles between the photocell and the observed image, one of the photocells being provided with a focusing lens for part of the image.
Inventors
- 👤 Minoru Suzuki
- 👤 Naoyuki Uno
- 👤 Tadazumi Sakazaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 13:04
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/099; G03B7/0993; G03B7/0997; G03B7/09971; G03B7/09976
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
119 words
A camera through the lens light-measuring system comprising viewing means including a pentaprism having a bottom face exposed to the image formed by the camera objective lens, a transparent rear face, a reflector front face and a reflector top surface and an eyepiece directed toward said pentaprism rear face, said pentaprism front face including an area which intercepts and reflects the light rays from said image to said eyepiece and a transparent section offset from said intercept area, and out of the path of light rays between said image and eyepiece and lightmeasuring means including a photosensitive element exposed to light rays entering said pentaprism bottom face and reflected by said top surface through said front face transparent section.
Claim 2
Dependent Claim
119 words
A camera through the lens light-measuring system comprising viewing means including a pentaprism having a bottom face exposed to the image formed by the camera objective lens, a transparent rear face, a reflector front face and a reflector top surface and an eyepiece directed toward said pentaprism rear face, said pentaprism front face including an area which intercepts and reflects the light rays from said image to said eyepiece and a transparent section offset from said intercept area, and out of the path of light rays between said image and eyepiece and lightmeasuring means including a photosensitive element exposed to light rays entering said pentaprism bottom face and reflected by said top surface through said front face transparent section.
Claim 3
Dependent Claim
20 words
The light-measuring systems of claim 1 wherein said transparent section is laterally offset relative to said front face intercept area.
Claim 4
Dependent Claim
45 words
The light-measuring system of claim 1 wherein and said photosensitive element is directed upwardly and is positioned below said transparent section and said light measuring means includes means directing said light rays reflected by said top surface through said transparent action onto said photosensitive element.
Claim 5
Dependent Claim
65 words
The light-measuring systems of claim 3 wherein said light ray directing means comprises a light deflecting prism proximate said front face transparent section and including a rear face adjacent said transparent section, a bottom face adjacent said photosensitive element and a front face reflecting said light rays entering said light deflecting prism rear face through said light deflecting prism bottom face onto said photosensitive element.
Claim 6
Dependent Claim
28 words
The light-reflecting system of claim 3 wherein said light ray-directing means comprise a mirror positioned forward of and facing said transparent section and forming an acute angle therewith.
Claim 7
Dependent Claim
39 words
The light-reflecting system of claim 1 including a lens positioned between said pentaprism front face transparent sections and said photosensitive element and directing the rays from a limited predetermined area of said viewed picture area onto said photosensitive element.
Claim 8
Dependent Claim
109 words
The light-measuring system of claim 1 including a pair of said transparent sections laterally offset on opposite sides of said pentaprism front face intercept area, one of said light-measuring means being associated with each of said transparent areas and each including one of said photosensitive elements positioned below a respective transparent section and means for directing said light rays reflected by said pentaprism top surface through said transparent section onto respective photosensitive elements, and means including a lens positioned between one of said photosensitive elements and a respective transparent section for directing the rays from a limited predetermined area of said viewed picture area to said respective photosensitive element.
Claim 9
Dependent Claim
38 words
The light-measuring system of claim 1 wherein said photosensitive element has a sensitive face at an oblique angle with the optical axis of said image forming light rays as directed through said prism and said pentaprism front face.
Claim 10
Dependent Claim
176 words
A camera through the lens light-measuring system comprising a viewer including a surface positioned in a focal plane of the camera lens and upon which an image is focused and a pentaprism having a face directed toward said image, a first photosensitive element exposed to said image through said pentaprism and having a sensitive face offset from and at an oblique angle with the optical axis of said image through said pentaprism to compensate for variations in light from different areas of said image incident on said sensitive face consequent to said offset from said optical axis, a second photosensitive element spaced from said other photosensitive element and exposeD to said image through said pentaprism and having a sensitive face offset from and at an oblique angle with the optical axis of said image through said pentaprism to compensate for variations in light from different areas of said image incident on said sensitive face, and a lens positioned to direct the rays from a limited predetermined area of said image on one of said photosensitive elements.
Claim 11
Dependent Claim
176 words
A camera through the lens light-measuring system comprising a viewer including a surface positioned in a focal plane of the camera lens and upon which an image is focused and a pentaprism having a face directed toward said image, a first photosensitive element exposed to said image through said pentaprism and having a sensitive face offset from and at an oblique angle with the optical axis of said image through said pentaprism to compensate for variations in light from different areas of said image incident on said sensitive face consequent to said offset from said optical axis, a second photosensitive element spaced from said other photosensitive element and exposeD to said image through said pentaprism and having a sensitive face offset from and at an oblique angle with the optical axis of said image through said pentaprism to compensate for variations in light from different areas of said image incident on said sensitive face, and a lens positioned to direct the rays from a limited predetermined area of said image on one of said photosensitive elements.
Claim 12
Dependent Claim
177 words
A camera through the lens light-measuring system comprising a viewer including a surface positioned in a focal plane of the camera and upon which an image is focused and a pentaprism having a bottom first face exposed to said image and second faces including a transparent rear face, a reflector front face and a reflector top face, and an eyepiece directed toward said pentaprism rear face, one of said pentaprism second faces including an area which intercepts light rays from said image to said eyepiece and a transparent section offset from said intercept area and located out of the path of light rays between said image and eyepiece, and a photosensitive element exposed to light rays from said image incident on said pentaprism first face and transversing said transparent section and having a sensitive face offset from and at an oblique angle with the optical axis of said image through said pentaprism to compensate for variations in light from different areas of said image incident on said sensitive face consequent to said offset from said optical axis.
Claim 13
Dependent Claim
177 words
A camera through the lens light-measuring system comprising a viewer including a surface positioned in a focal plane of the camera and upon which an image is focused and a pentaprism having a bottom first face exposed to said image and second faces including a transparent rear face, a reflector front face and a reflector top face, and an eyepiece directed toward said pentaprism rear face, one of said pentaprism second faces including an area which intercepts light rays from said image to said eyepiece and a transparent section offset from said intercept area and located out of the path of light rays between said image and eyepiece, and a photosensitive element exposed to light rays from said image incident on said pentaprism first face and transversing said transparent section and having a sensitive face offset from and at an oblique angle with the optical axis of said image through said pentaprism to compensate for variations in light from different areas of said image incident on said sensitive face consequent to said offset from said optical axis.
Claim 14
Dependent Claim
60 words
The light-measuring systems of claim 10 wherein said pentaprism includes a rear transparent exit face, and comprising an eyepiece directed toward said rear face along said optical axis, said photosensitive element being laterally offset from and outside the angle of vision of said eyepiece and having a sensitive surface facing said pentaprism rear face and inclined toward said optical axis.
Claim 15
Dependent Claim
26 words
The light-measuring system of claim 10 including a lens positioned to direct the rays from a limited predetermined area of said image onto said photosensitive element.
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) | 1974-02-15 | 1974-08-17 | 1975-02-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-15 | 1978-08-17 | 1979-02-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-15 | 1982-08-17 | 1983-02-16 | $7700.00 | Window Closed / Lapsed |