US3921184A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Compensation of response sluggishness of photoelements employed in automatic exposure timers
Assignee: Agfa Gevaert AG
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Filing: 1974-05-08
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Granted: 1975-11-18
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Expires: 1994-05-08
Abstract
Abstract A photographic camera is adapted for making exposures with and also without a photoflash unit. A photosensitive unit is operative for detecting scene brightness, but exhibits a disadvantageous time delay in the detection of a sudden scene brightness increase such as occurs when a photoflash unit produces a flash. An automatic exposure timing arrangement is operative for automatically selecting the time duration of an exposure in dependence upon the scene brightness detected by the photosensitive unit during the making of the exposure. An exposure-type selector has a first setting for photoflash exposures and a second setting for natural-light and other exposures. A compensation arrangement is operative for counteracting the effect of the aforementioned time delay upon the operation of the timing arrangement, in order to counteract any tendency of the timing arrangement to select too long an exposure time when the camera makes a photoflash exposure. The compensation arrangement includes an exposure-shortening device operative for causing the timing arrangement to automatically select shorter exposure times when the exposure-type selector is in the first setting than when the exposure-type selector is in the second setting.
Inventors
- 👤 Kurt Borowski
- 👤 Friedrich Stumpf
- 👤 Eduard Wagensonner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 01:02
CPC Classifications
G; G03; G03B; G03B9/00; G03B9/70; G03B7/00; G03B7/16
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
205 words
In a photographic camera of the type adapted for making exposures with and also without a photoflash unit, in combination, photosensitive means operative for detecting scene brightness but exhibiting a time delay in the detection of a sudden scene brightness increase such as occurs when a photoflash unit produces a flash; exposure-type selecting means having a first setting for photoflash exposures and a second setting for other exposures; an automatic exposure timing arrangement operative for automatically selecting the time duration of an exposure in dependence upon the scene brightness detected by said photosensitive means during the making of the exposure, both when said exposure-type selecting means is in said first setting and when said exposure-type selecting means is in said second setting; and compensating means operative for counteracting the effect of said time delay upon the operation of said timing arrangement in order to counteract any tendency of said timing arrangement to select too long an exposure time when the camera makes a photoflash exposure, said compensating means comprising exposure-shortening means operative for causing said timing arrangement to automatically select shorter scene-brightnessdependent exposure times when said exposure-type selecting means is in said first setting than when said exposure-type selecting means is in said second setting.
Claim 2
Dependent Claim
205 words
In a photographic camera of the type adapted for making exposures with and also without a photoflash unit, in combination, photosensitive means operative for detecting scene brightness but exhibiting a time delay in the detection of a sudden scene brightness increase such as occurs when a photoflash unit produces a flash; exposure-type selecting means having a first setting for photoflash exposures and a second setting for other exposures; an automatic exposure timing arrangement operative for automatically selecting the time duration of an exposure in dependence upon the scene brightness detected by said photosensitive means during the making of the exposure, both when said exposure-type selecting means is in said first setting and when said exposure-type selecting means is in said second setting; and compensating means operative for counteracting the effect of said time delay upon the operation of said timing arrangement in order to counteract any tendency of said timing arrangement to select too long an exposure time when the camera makes a photoflash exposure, said compensating means comprising exposure-shortening means operative for causing said timing arrangement to automatically select shorter scene-brightnessdependent exposure times when said exposure-type selecting means is in said first setting than when said exposure-type selecting means is in said second setting.
Claim 3
Dependent Claim
194 words
In a photographic camera as defined in claim 1, wherein said automatic exposure timing arrangement comprises exposure-terminating means activatable for terminating an exposure, voltage-detecting means having an output across which is connected said exposure-terminating means and having an input and operative for activating said exposure-terminating means when the voltage across said input reaches a predetermined value, a voltage source, a timing capacitor stage including at least one timing capacitor, and connecting means operative during an exposure of either type for connecting together said voltage source, said photosensitive means and said timing capacitor circuit to cause a flow of scene-brightness-dependent current through said timing capacitor to cause said timing capacitor stage to apply to said input of said voltage-detecting means a voltage dependent upon the voltage across said timing capacitor and changing at a scene-brightness-dependent rate from an initial value to said predetermined value, and wherein said exposure-shortening means comprises means operative for establishing an initial value of the voltage across said input of said voltage-detecting means which is nearer to said predetermined value when said exposure-type selecting means is in said first setting than when said exposure-type selecting means is in said second setting.
Claim 4
Dependent Claim
156 words
In a photographic camera as defined in claim 1, wherein said automatic exposure timing arrangement comprises exposure-terminating means activatable for terminating an exposure, voltage-detecting means having an output across which is connected said exposure-terminating means and having an input and operative for activating said exposure-terminating means when the voltage across said input reaches a predetermined value, a voltage source, and a timing capacitor, and wherein said photosensitive means comprises a photoelement, and wherein said photoelement and said timing capacitor are connected in series across said voltage source to form a voltage divider having two branches, one of the branches including said photoelement and the other of said branches including said timing capacitor, one of said branches being connected across said input of said voltage-detecting means, and wherein said exposure-shortening means comprises means for varying the resistance of the voltage divider branch which includes said timing capacitor in dependence upon the setting of said exposure-type selecting means.
Claim 5
Dependent Claim
49 words
In a photographic camera as defined in claim 1, further including distance-setting means, and wherein said exposure-shortening means comprises meaNs operative when said exposure-type selecting means is in said first setting for effecting an exposure-time shortening which varies inversely to the distance for which said distance-setting means is set.
Claim 6
Dependent Claim
152 words
In a photographic camera as defined in claim 1, wherein said automatic exposure timing arrangement comprises exposure-terminating means activatable for terminating an exposure, voltage-detecting means having an output across which is connected said exposure-terminating means and having an input and operative for activating said exposure-terminating means when the voltage across said input reaches a predetermined value, a voltage source, and a timing capacitor, and wherein said photosensitive means comprises a photoelement, and wherein said photoelement and said timing capacitor are connected in series across said voltage source to form a voltage divider having two branches, one of the branches including said photoelement and the other of said branches including said timing capacitor, one of said branches being connected across said input of said voltage-detecting means, and wherein said exposure-shortening means comprises means for varying the ratio of the resistances of said branches in dependence upon the setting of said exposure-type selecting means.
Claim 7
Dependent Claim
222 words
In a photographic camera of the type adapted for making exposures with and also without a photoflash unit, in combination, photosensitive means operative for detecting scene brightness but exhibiting a time delay in the detection of a sudden scene brightness increase such as occurs when a photoflash unit produces a flash; an automatic exposure timing arrangement operative for automatically selecting the time duration of an exposure in dependence upon the scene brightness detected by said photosensitive means during the making of the exposure; exposure-type selecting means having a first setting for photoflash exposures and a second setting for other exposures; and compensation means operative for counteracting the effect of said time delay upon the operation of said timing arrangement in order to counteract any tendency of said timing arrangement to select too long an exposure time when the camera makes a photoflash exposure, said compensation means comprising exposure-shortening means operative for causing said timing arrangement to automatically select shorter exposure times when said exposure-type selecting means is in said first setting than when said exposure-type selecting means is in said second setting, further including distance-setting means, and wherein said exposure-shortening means comprises means operative when said exposure-type selecting means is in said first setting for affecting an exposure-time shortening which varies inversely to the distance for which said distance-setting means is set.
Claim 8
Dependent Claim
222 words
In a photographic camera of the type adapted for making exposures with and also without a photoflash unit, in combination, photosensitive means operative for detecting scene brightness but exhibiting a time delay in the detection of a sudden scene brightness increase such as occurs when a photoflash unit produces a flash; an automatic exposure timing arrangement operative for automatically selecting the time duration of an exposure in dependence upon the scene brightness detected by said photosensitive means during the making of the exposure; exposure-type selecting means having a first setting for photoflash exposures and a second setting for other exposures; and compensation means operative for counteracting the effect of said time delay upon the operation of said timing arrangement in order to counteract any tendency of said timing arrangement to select too long an exposure time when the camera makes a photoflash exposure, said compensation means comprising exposure-shortening means operative for causing said timing arrangement to automatically select shorter exposure times when said exposure-type selecting means is in said first setting than when said exposure-type selecting means is in said second setting, further including distance-setting means, and wherein said exposure-shortening means comprises means operative when said exposure-type selecting means is in said first setting for affecting an exposure-time shortening which varies inversely to the distance for which said distance-setting means is set.
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) | 1978-11-17 | 1979-05-19 | 1979-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-17 | 1983-05-19 | 1983-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-17 | 1987-05-19 | 1987-11-18 | $7700.00 | Window Closed / Lapsed |