US3711644A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic diaphragm control apparatus for image tube
Assignee: Nidec Precision Corp
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Filing: 1971-09-17
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Granted: 1973-01-16
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Expires: 1991-09-17
Abstract
Abstract An automatic diaphragm control apparatus for image tube comprising a diaphragm means for controlling the amount of light incident to the light-receiving plane of an image tube, a photoconductive cell for receiving a part of the light having passed through the diaphragm means, a Wheatstone bridge circuit including the photoconductive cell in one of the branches thereof, a servo-motor adapted to be driven by the unbalanced voltage occurring in the bridge circuit and assigned for operating the diaphragm means, and a switch means interlocked with the power switches and adapted to act to momentarily elevate - prior to the opening of the power switches - the potential of one of the two output terminals of the bridge circuit to a level exceeding that of the potential of the other of the output terminals, the apparatus being operative so that, whenever the power switches are opened, the diaphragm means is always held at its minimum diaphragm aperture position, preventing the lightreceiving plane of the image tube from sustaining any damage from burning caused by the intensive ambient light incident towards this light-receiving plane.
Inventors
- 👤 Y Ishiguro
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 09:46
CPC Classifications
H; H04; H04N; H04N23/00; H04N23/40
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
202 words
An automatic diaphragm control apparatus for image tube comprising in combination an image tube, a half mirror provided in the foreground of a light-receiving plane of said image tube in adjacent relationship therewith, a diaphragm means positioned in the foreground of said half mirror in adjacent relationship with said half mirror, a photoconductive cell positioned adjacent to said half mirror and adapted to receive a part of the light having passed through said diaphragm means, a Wheatstone bridge circuit containing said photoconductive cell in one of its branches, an amplifier connected between the output terminals of said bridge circuit, a servo-motor connected to the output terminal of said amplifier, and power switches connected to the input terminals of said bridge circuit, respectively, wherein said automatic diaphragm control apparatus further comprises means arranged to act in interlocking relationship with said power switches and to be operative to momentarily elevate the potential level of one of the output terminals of said bridge circuit to a level higher than the potential level of the other one of these output terminals immediately before said power switches are opened, whereby said diaphragm means is held at its minimum diaphragm aperture position whenever said power switches are opened.
Claim 2
Dependent Claim
202 words
An automatic diaphragm control apparatus for image tube comprising in combination an image tube, a half mirror provided in the foreground of a light-receiving plane of said image tube in adjacent relationship therewith, a diaphragm means positioned in the foreground of said half mirror in adjacent relationship with said half mirror, a photoconductive cell positioned adjacent to said half mirror and adapted to receive a part of the light having passed through said diaphragm means, a Wheatstone bridge circuit containing said photoconductive cell in one of its branches, an amplifier connected between the output terminals of said bridge circuit, a servo-motor connected to the output terminal of said amplifier, and power switches connected to the input terminals of said bridge circuit, respectively, wherein said automatic diaphragm control apparatus further comprises means arranged to act in interlocking relationship with said power switches and to be operative to momentarily elevate the potential level of one of the output terminals of said bridge circuit to a level higher than the potential level of the other one of these output terminals immediately before said power switches are opened, whereby said diaphragm means is held at its minimum diaphragm aperture position whenever said power switches are opened.
Claim 3
Dependent Claim
107 words
An automatic diaphragm control apparatus according to claim 1, in which said means arranged to act in interlocking relationship with said power switches and to be operative to momentarily elevate the potential level of one of the output terminals of said bridge circuit to a level higher than that of the other one of these output terminals immediately before the opening of said power switches is a switch inserted in one of those two branches of said bridge circuit which are connected to the photoconductive cell and adapted to be opened prior to the opening of said power switches when these power switches are to be opened.
Claim 4
Dependent Claim
104 words
An automatic diaphragm control apparatus according to claim 1, in which said means arranged to act in interlocking relationship with said power switches and to be operative to momentarily elevate the potential level of one of the output terminals of said bridge circuit to a level higher than that of these output terminals immediately before the opening of said power switches is a switch connected in parallel with one of the resistors contained in those branches of said bridge circuit which face either said photoconductive cell or the branch containing this photoconductive cell and adapted to be closed before said power switches are opened.
References Cited (Backward Citations)
US3496289A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-01-16 | 1976-07-17 | 1977-01-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-16 | 1980-07-17 | 1981-01-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-16 | 1984-07-17 | 1985-01-16 | $7700.00 | Window Closed / Lapsed |