Patent US3800655A successfully refreshed from Google Patents.
US3800655A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photographic viewfinder arrangement
Assignee: Minolta Co Ltd
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Filing: 1972-12-14
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Granted: 1974-04-02
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Expires: 1992-12-14
Abstract
Abstract A viewfinder arrangement which comprises a pentagonal prism, an auxiliary prism cemented to the pentagonal prism, a reflective element for reflecting images of the adjusting scales towards the axuiliary prism whereby the length of the optical path from the adjusting scale on the camera lens barrel to the eye of a photographer through the auxiliary prism and the pentagonal prism by means of the reflective element is made longer than the length of the optical path from the camera focusing plate to the photographer''s eye, and an optical element for compensating for the difference between these two optical paths. The auxiliary prism has an additional entrance for transmitting a beam of light carrying a shutter speed information to the eye of the photographer.
Inventors
- 👤 I Uchida
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 12:53
CPC Classifications
G; G03; G03B; G03B19/00; G03B19/02; G03B19/12
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
140 words
A viewfinder arrangement for a single lens reflex camera which comprises in combination: a focusing screen; an eyepiece; a pentagonal prism positioned to direct a beam of light passing through said focusing screen into said eyepiece; an auxiliary prism mounted on said pentagonal prism for directing a further beam of light entering said auxiliary prism into said eyepiece by means of reflection by a front lower reflection plane of said pentagonal prism; an exposure condition adjusting member having a scale and operatively positioned; a reflecting member operatively located for directing an image of said scale of said exposure condition adjusting member to said auxiliary prism; and a concave lens operatively positioned for substantially equalizing the optical distance from said scale of said exposure condition adjusting member to said eyepiece with the optical distance from said focusing screen to said eyepiece.
Claim 2
Dependent Claim
140 words
A viewfinder arrangement for a single lens reflex camera which comprises in combination: a focusing screen; an eyepiece; a pentagonal prism positioned to direct a beam of light passing through said focusing screen into said eyepiece; an auxiliary prism mounted on said pentagonal prism for directing a further beam of light entering said auxiliary prism into said eyepiece by means of reflection by a front lower reflection plane of said pentagonal prism; an exposure condition adjusting member having a scale and operatively positioned; a reflecting member operatively located for directing an image of said scale of said exposure condition adjusting member to said auxiliary prism; and a concave lens operatively positioned for substantially equalizing the optical distance from said scale of said exposure condition adjusting member to said eyepiece with the optical distance from said focusing screen to said eyepiece.
Claim 3
Dependent Claim
39 words
A viewfinder arrangment as claimed in claim 1, wherein said exposure condition adjusting member comprises a focal distance adjusting member and a diaphragm setting member and wherein said reflecting member carries an image of said exposure condition adjusting member.
Claim 4
Dependent Claim
39 words
A viewfinder arrangement as claimed in claim 1, wherein said pentagonal prism has a front upper non-reflecting plane with a substantially V-shaped seat therein to which said auxiliary prism is firmly mounted to fit with said substantially V-shaped seat.
Claim 5
Dependent Claim
68 words
A viewfinder arrangement as claimed in claim 1, wherein said auxiliary prism has an incident plane facing at least one indicium indicative of a selected value of said exposure condition adjusting member and permitting the entry said further beam of light, said further beam of light entering said auxiliary prism being directed into said eyepiece through the reflection by said front lower reflection plane of said pentagonal prism.
Claim 6
Dependent Claim
54 words
A viewfinder arrangement as claimed in claim 1, wherein said auxiliary prism has at least two reflection planes and said beam of light entering said auxiliary prism being carried to a front lower reflecting plane of said pentagonal prism after having been reflected by each of said two reflection planes of said auxiliary prism.
Claim 7
Dependent Claim
24 words
A viewfinder arrangement as claimed in claim 1, wherein said concave lens is disposed between said exposure condition adjusting member and said reflecting member.
Claim 8
Dependent Claim
22 words
A viewfinder arrangement as claimed in claim 1, wherein said concave lens is disposed between said reflecting member and said auxiliary prism.
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) | 1977-04-01 | 1977-10-01 | 1978-04-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-01 | 1981-10-01 | 1982-04-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-01 | 1985-10-01 | 1986-04-02 | $7700.00 | Window Closed / Lapsed |