US3783765A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photometric device in a single lens reflex camera of through-the-lens type
Assignee: Pentax Corp
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Filing: 1972-08-07
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Granted: 1974-01-08
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Expires: 1992-08-07
Abstract
Abstract A single lens reflex camera of through-the lens type having an objective lens, a pentaprism, a snap-up mirror and a viewfinder and providing a light path for an image between the objective lens and the viewfinder across the mirror and through the pentaprism. An electrically controlled shutter system of throughthe-lens type is provided having a photosensitive sensing element located in the light path and in the path of light from the viewfinder. A light intercepting means is provided together with means for moving the light intercepting means into and out of the light path at a position along the light path in between the pentaprism and the mirror.
Inventors
- 👤 N Uno
- 👤 K Nomura
- 👤 T Sakazaki
- 👤 F Urano
- 👤 K Watanabe
- 👤 K Miyata
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 08:53
CPC Classifications
G; G03; G03B; G03B19/00; G03B19/02; G03B19/12; G03B7/00; G03B7/08; G03B7/099; G03B7/0993; G03B7/0997; G03B7/09971; G03B7/09976; G03B7/09978
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
144 words
A single lens reflex camera of through-the-lens viewing type, having an objective lens, a pentaprism, a snap-up mirror, and a view finder and providing a light path for an image between the objective lens and view finder across the mirror through the pentaprism, the camera having an electrically controlled shutter system and a light metering system of through-the-lens type for control of the shutter and having a photo-sensitive sensing element for control of the metering system, the photo-sensitive element being located both in the light path and in the path of light from the view finder, the improvement comprising: light intercepting means for preventing the light from the objective lens from reaching the photosensing element; and means for moving the light intercepting means into and out of the light path at a position along the light path in between the pentaprism and the mirror.
Claim 2
Dependent Claim
144 words
A single lens reflex camera of through-the-lens viewing type, having an objective lens, a pentaprism, a snap-up mirror, and a view finder and providing a light path for an image between the objective lens and view finder across the mirror through the pentaprism, the camera having an electrically controlled shutter system and a light metering system of through-the-lens type for control of the shutter and having a photo-sensitive sensing element for control of the metering system, the photo-sensitive element being located both in the light path and in the path of light from the view finder, the improvement comprising: light intercepting means for preventing the light from the objective lens from reaching the photosensing element; and means for moving the light intercepting means into and out of the light path at a position along the light path in between the pentaprism and the mirror.
Claim 3
Dependent Claim
25 words
A single lens reflex camera according to claim 1 comprising means actuable external from the camera for controlling the movement of the light intercepting means.
Claim 4
Dependent Claim
57 words
A single lens reflex camera according to claim 2 wherein said means for moving normally holds the light intercepting means out of the light path between the objective lens and view finder, and the actuable means actuates the light intercepting means into the light path, thereby preventing light from the objective lens from reaching said photosensitive element.
Claim 5
Dependent Claim
18 words
A single lens reflex camera according to claim 3 wherein said light intercepting means is a movable plate.
Claim 6
Dependent Claim
21 words
A signle lens reflex camera according to claim 1 wherein said light intercepting means absorbs the light from said viewfinder lens.
Claim 7
Dependent Claim
200 words
A single lens reflex camera of through-the-lens viewing type, having an objective lens, a pentaprism, a snap-up mirror, and a view finder and providing a light path for an image between the objective lens and view finder across the mirror through the pentaprism, the camera having an electrically controlled shutter system and a light metering system of through-the-lens type for control of the shutter and having a photo-sensitive sensing element for control of the metering system, the photo-sensitive element being located both in the light path and in the path of light from the view finder, the improvement comprising: a manually operable shutter release button and a light intercepting member for preventing light from reaching the photo-sensitive element, the method of indicating the amount of light from the view finder reaching the photo-sensitive element comprising the steps of: a. responsive to depressing movement of the shutter release button, moving the light intercepting member into the light path from the objective lens, and b. directing the light intercepting member at a position in between the pentaprism and the mirror, thereby preventing light from the objective lens from reaching the photo-sensing element while light from the view finder reaches the photo-sensitive element.
Claim 8
Dependent Claim
200 words
A single lens reflex camera of through-the-lens viewing type, having an objective lens, a pentaprism, a snap-up mirror, and a view finder and providing a light path for an image between the objective lens and view finder across the mirror through the pentaprism, the camera having an electrically controlled shutter system and a light metering system of through-the-lens type for control of the shutter and having a photo-sensitive sensing element for control of the metering system, the photo-sensitive element being located both in the light path and in the path of light from the view finder, the improvement comprising: a manually operable shutter release button and a light intercepting member for preventing light from reaching the photo-sensitive element, the method of indicating the amount of light from the view finder reaching the photo-sensitive element comprising the steps of: a. responsive to depressing movement of the shutter release button, moving the light intercepting member into the light path from the objective lens, and b. directing the light intercepting member at a position in between the pentaprism and the mirror, thereby preventing light from the objective lens from reaching the photo-sensing element while light from the view finder reaches the photo-sensitive element.
Claim 9
Dependent Claim
53 words
In a camera, the method according to claim 6 comprising the additional steps of: a. moving the mirror out of the path of light from the objective lens; and b. substantially simultaneously with moving the mirror, performing said step of moving the light intercepting member into the light path from the objective lens.
Claim 10
Dependent Claim
29 words
In a camera, the method according to claim 7 wherein said step of moving the light intercepting plate takes place immediately prior to the step of moving the mirror.
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) | 1977-01-07 | 1977-07-09 | 1978-01-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-07 | 1981-07-09 | 1982-01-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-07 | 1985-07-09 | 1986-01-08 | $7700.00 | Window Closed / Lapsed |