US4359275A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Single lens reflex camera system capable of TTL flash output control
Assignee: Nikon Corp
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Filing: 1980-12-11
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Granted: 1982-11-16
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Expires: 2000-12-11
Abstract
Abstract A single lens reflex camera system capable of TTL flash output control of a flash unit which enables transmission light from the phototaking lens from a movable mirror device to a light receiving device when the mirror device is in one position and from a film surface to the light receiving device when the mirror is in a second position, the light receiving device generating a signal corresponding to the quantity of light it receives. A trigger circuit enables flash tube actuation upon film exposure and a control device controls the quantity of light emission of the tube in response to the output of the light receiving device. The trigger circuit is actuated when the mirror device is in the one position by an actuating device which includes circuitry for correcting the response of the control device of the output of the light receiving device in accordance with the difference, with respect to the same object, between the quantity of light incident on the light receiving device when the mirror device is in the one position and the quantity of light incident on the light receiving device when the mirror device is in the second position.
Inventors
- 👤 Hiroshi Hasegawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 05:13
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G03B7/083; G03B7/099; G03B7/0993; G03B7/0997; G03B7/09971; G03B7/09972
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
246 words
In a system for taking pictures which is capable of flash photography and which includes a movable mirror device formed with a light-transmitting portion, the mirror being movable between an observation position in which the mirror reflects light from a phototaking lens to a view finder and also transmits the light from the phototaking lens through the light-transmitting portion, and a photographing position retracted from the photographing light path; a light receiving device positioned to be capable of receiving the light transmitted through the movable mirror device and the light reflected by a film surface, the light receiving device generating a photoelectric signal corresponding to the quantity of the received light; a trigger circuit for firing a flash tube in synchronization with exposure of the film surface by the light; and a flash unit having a flash output control device for controlling the quantity of light emission of the flash tube in response to the photoelectric output; the improvement comprising: means for arbitrarily actuating said trigger circuit when said movable mirror device is in the observation position, the actuating means including means for correcting the response of said flash output control device to said photoelectric output in accordance with the difference, with respect to the same object, between the light quantity incident on said light receiving device when the movable mirror device is in the observation position and the light quantity incident on said light receiving device when the movable mirror is in the photographing position.
Claim 2
Dependent Claim
246 words
In a system for taking pictures which is capable of flash photography and which includes a movable mirror device formed with a light-transmitting portion, the mirror being movable between an observation position in which the mirror reflects light from a phototaking lens to a view finder and also transmits the light from the phototaking lens through the light-transmitting portion, and a photographing position retracted from the photographing light path; a light receiving device positioned to be capable of receiving the light transmitted through the movable mirror device and the light reflected by a film surface, the light receiving device generating a photoelectric signal corresponding to the quantity of the received light; a trigger circuit for firing a flash tube in synchronization with exposure of the film surface by the light; and a flash unit having a flash output control device for controlling the quantity of light emission of the flash tube in response to the photoelectric output; the improvement comprising: means for arbitrarily actuating said trigger circuit when said movable mirror device is in the observation position, the actuating means including means for correcting the response of said flash output control device to said photoelectric output in accordance with the difference, with respect to the same object, between the light quantity incident on said light receiving device when the movable mirror device is in the observation position and the light quantity incident on said light receiving device when the movable mirror is in the photographing position.
Claim 3
Dependent Claim
62 words
A system according to claim 1, wherein said flash output control means includes a circuit for integrating said photoelectric output with respect to time and generating a control signal for stopping the light emission of the flash tube when the integrated value amounts to a predetermined value; and said correcting means includes a circuit for adjusting the level of the predetermined value.
Claim 4
Dependent Claim
29 words
A system according to claim 2, wherein said flash unit includes means for displaying a state controlled by said flash output control device, in response to said control signal.
Claim 5
Dependent Claim
84 words
A system according to claim 2, further comprising a diaphragm device stopped down to a preset position during said exposure, a diaphragm preset member for setting the preset position of said diaphragm device, and means operatively associated with said diaphragm preset member to vary the level of the predetermined value of said integrating circuit by an amount corresponding to the difference between the outputs of said light receiving device during the opening of said diaphragm device and during the stop-down of said diaphragm device.
Claim 6
Dependent Claim
217 words
In a system for taking pictures which is capable of flash photography and which comprises a camera including a movable mirror device formed with a light-transmitting portion, the mirror being movable between an observation position in which the mirror reflects light from a phototaking lens to a view finder and also transmits the light from the phototaking lens through the light-transmitting portion and a photographing position retracted from the photographing light path, a light receiving device positioned to be capable of receiving the light transmitted through the movable mirror device and the light reflected by a film surface and generating a photoelectric output corresponding to the quantity of the received light and a metering circuit for generating an output in correspondence with said photoelectric output; and a flash unit comprising a trigger circuit for firing a flash tube in synchronization with exposure of the film surface by said light, a flash output control device for controlling the quantity of the light emission of the flash tube and means for electrically connecting the flash output control device to the camera; the improvement wherein: said metering circuit includes means for amplifying said photoelectric output, and means having a transistor connected to the amplifying means and transmitting to said connecting means an electric current output corresponding to said photoelectric output.
Claim 7
Dependent Claim
217 words
In a system for taking pictures which is capable of flash photography and which comprises a camera including a movable mirror device formed with a light-transmitting portion, the mirror being movable between an observation position in which the mirror reflects light from a phototaking lens to a view finder and also transmits the light from the phototaking lens through the light-transmitting portion and a photographing position retracted from the photographing light path, a light receiving device positioned to be capable of receiving the light transmitted through the movable mirror device and the light reflected by a film surface and generating a photoelectric output corresponding to the quantity of the received light and a metering circuit for generating an output in correspondence with said photoelectric output; and a flash unit comprising a trigger circuit for firing a flash tube in synchronization with exposure of the film surface by said light, a flash output control device for controlling the quantity of the light emission of the flash tube and means for electrically connecting the flash output control device to the camera; the improvement wherein: said metering circuit includes means for amplifying said photoelectric output, and means having a transistor connected to the amplifying means and transmitting to said connecting means an electric current output corresponding to said photoelectric output.
Claim 8
Dependent Claim
37 words
A system according to claim 5, wherein said amplifying means includes means for generating an output which is a logarithmic compression of said photoelectric output, and said transistor is connected to the base of said amplifying means.
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) | 1985-11-15 | 1986-05-17 | 1986-11-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-11-15 | 1990-05-17 | 1990-11-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-11-15 | 1994-05-17 | 1994-11-16 | $7700.00 | Window Closed / Lapsed |