US3868702A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Mirror reflex camera
Assignee: Rollei Werke Franke und Heidecke GmbH and Co KG
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Filing: 1973-11-16
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Granted: 1975-02-25
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Expires: 1993-11-16
Abstract
Abstract A mirror reflex camera of the type in which a diaphragm adjusting member is driven from maximum diaphragm aperture position toward minimum aperture position, and in which a photocell receiving light through the lens and the diaphragm is part of an electronic circuit which stops the closing down movement of the diaphragm aperture adjusting member when the photocell senses that the diaphragm has reached the proper aperture for the intended photographic exposure. The invention relates particularly to the brake which stops the movement of the diaphragm adjusting mechanism when the aperture is at the proper point. A rotating disk which is part of the adjusting mechanism normally has a very small air gap from the poles of an electromagnet. When the magnet is energized, it draws the disk into actual contact with the poles of the magnet, forming an effective quick-acting brake. The electronic circuit is adjusted to energize the electro-magnet shortly before the diaphragm reaches the desired aperture, to compensate for the unavoidable time lag in operation of even a quick-acting brake of this kind, so that when the movement is stopped by the brake, the aperture will be at the desired value.
Inventors
- 👤 Karl-Peter Strauss
- 👤 Richard Weiss
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 14:51
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G03B7/085
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
129 words
A mirror reflex camera of the type having a lens, a diaphragm of adjustable aperture, a photocell receiving light through said lens and diaphragm, drive means for varying the aperture of the diaphragm, and means for arresting movement of said drive means when a desired aperture size is reached during operation of said drive means, characterized by the fact that a ferro magnetic disk is coupled to said drive means to move therewith, and that an electro-magnet has a pole piece normally located close to said disk with a small clearance, and means for magnetizing said electro-magnet when said drive means is to be arrested, to cause said electro-magnet to act as a brake to stop movement of said disk and thereby to arrest movement of said drive means.
Claim 2
Dependent Claim
129 words
A mirror reflex camera of the type having a lens, a diaphragm of adjustable aperture, a photocell receiving light through said lens and diaphragm, drive means for varying the aperture of the diaphragm, and means for arresting movement of said drive means when a desired aperture size is reached during operation of said drive means, characterized by the fact that a ferro magnetic disk is coupled to said drive means to move therewith, and that an electro-magnet has a pole piece normally located close to said disk with a small clearance, and means for magnetizing said electro-magnet when said drive means is to be arrested, to cause said electro-magnet to act as a brake to stop movement of said disk and thereby to arrest movement of said drive means.
Claim 3
Dependent Claim
24 words
A device as defined in claim 1, wherein said disk is flexibly supported for movement toward said pole piece when said electro-magnet is magnetized.
Claim 4
Dependent Claim
38 words
A device as defined in claim 2, wherein said disk is mounted on a bendable shaft in such a way that the shaft bends under the influence of the magnetized electro-magnet until the disk touches said pole piece.
Claim 5
Dependent Claim
17 words
A device as defined in claim 3, wherein the periphery of the disk touches the pole piece.
Claim 6
Dependent Claim
48 words
A device as defined in claim 2, wherein said disk is axially movable on a shaft and is biased axially in a direction away from said pole piece, and said electro-magnet when magnetized draws said disk axially to bring a face thereof into contact with said pole piece.
Claim 7
Dependent Claim
75 words
A device as defined in claim 1, wherein said drive means moves said diaphragm from maximum aperture in a direction toward minimum aperture, and wherein said means for magnetizing said electro-magnet is adjusted to magnetize said electro-magnet when the closing down movement of the diaphragm reaches a slightly larger aperture than the intended aperture appropriate for a desired photographic exposure, to compensate for a time lag in bringing the closing down movement to a halt.
Claim 8
Dependent Claim
129 words
Braking mechanism for stopping adjusting movement of a diaphragm aperture adjusting drive, comprising a shaft coupled to said drive to turn while the aperture of the diaphragm is changing, a ferro-magnetic disk mounted on said shaft to turn therewith, an electro-magnet having a pole piece close to a portion of said disk with a slight air gap between the pole piece and the disk so long as the adjusting drive is intended to perform adjusting movement, and a coil for magnetizing said electro-magnet when it is desired to stop the adjusting movement of said drive, said disk and magnet being so arranged that when said electro-magnet is magnetized, it will draw said disk into contact with said pole piece to produce a braking action stopping rotation of said disk.
Claim 9
Dependent Claim
129 words
Braking mechanism for stopping adjusting movement of a diaphragm aperture adjusting drive, comprising a shaft coupled to said drive to turn while the aperture of the diaphragm is changing, a ferro-magnetic disk mounted on said shaft to turn therewith, an electro-magnet having a pole piece close to a portion of said disk with a slight air gap between the pole piece and the disk so long as the adjusting drive is intended to perform adjusting movement, and a coil for magnetizing said electro-magnet when it is desired to stop the adjusting movement of said drive, said disk and magnet being so arranged that when said electro-magnet is magnetized, it will draw said disk into contact with said pole piece to produce a braking action stopping rotation of said disk.
Claim 10
Dependent Claim
35 words
A device as defined in claim 7, wherein said shaft is transversely flexible and bends to permit the periphery of said disk to close said air gap and come into contact with said pole piece.
Claim 11
Dependent Claim
48 words
A device as defined in claim 7, wherein said disk is resiliently displaceable in an axial direction on said shaft and is axially displaced upon magnetization of said electro-magnet so that a face of said disk closes said air gap and comes into contact with said pole piece.
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) | 1978-02-24 | 1978-08-26 | 1979-02-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-24 | 1982-08-26 | 1983-02-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-24 | 1986-08-26 | 1987-02-25 | $7700.00 | Window Closed / Lapsed |