US3972607A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Analog/digital control arrangement for photographic apparatus
Assignee: Agfa Gevaert AG
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Filing: 1974-12-30
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Granted: 1976-08-03
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Expires: 1994-12-30
Abstract
Abstract A bridge circuit which includes a photoelectric transducer furnishes input signals to a differential amplifier whose analog output signal varies in correspondence to the bridge unbalance. A first and second bistable threshold circuit changes the analog output signal into digital signals signifying bridge unbalance in a first direction, balance, and unbalance in the opposite direction. A motor is energized to rotate in a direction corresponding to the direction of bridge unbalance. The motor can be utilized to move the objective lens of a slide projector or change the aperture of a diaphragm.
Inventors
- 👤 Alois Reider
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 06:20
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G03B7/085; G02; G02B; G02B7/00; G02B7/28; G02B7/36
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
198 words
Photographic apparatus, comprising, in combination, photoelectric transducer means for furnishing a light-dependent signal varying as a function of light falling thereon; balanceable circuit means including said photoelectric transducer means for furnishing a first signal having an amplitude less than a predetermined first threshold amplitude when said balanceable circuit means is unbalanced in a first direction, an amplitude exceeding said predetermined first threshold amplitude and less than a predetermined second threshold amplitude when said balanceable circuit means is balanced, and an amplitude exceeding a predetermined second threshold amplitude when said balanceable circuit means is unbalanced in a second direction opposite to said first direction; first and second bistable circuit means connected to said balanceable circuit means and responsive to the amplitude of said first signal for furnishing a first, second or third digital output signal when said balanceable circuit means is unbalanced in said first direction, balanced, and unbalanced in said second direction respectively; and control means having an energizing circuit connected to said first and second bistable circuit means for varying the light falling on said photosensitive transducer means in response to said first and third digital output signals in a direction to rebalance said balanceable circuit means.
Claim 2
Dependent Claim
198 words
Photographic apparatus, comprising, in combination, photoelectric transducer means for furnishing a light-dependent signal varying as a function of light falling thereon; balanceable circuit means including said photoelectric transducer means for furnishing a first signal having an amplitude less than a predetermined first threshold amplitude when said balanceable circuit means is unbalanced in a first direction, an amplitude exceeding said predetermined first threshold amplitude and less than a predetermined second threshold amplitude when said balanceable circuit means is balanced, and an amplitude exceeding a predetermined second threshold amplitude when said balanceable circuit means is unbalanced in a second direction opposite to said first direction; first and second bistable circuit means connected to said balanceable circuit means and responsive to the amplitude of said first signal for furnishing a first, second or third digital output signal when said balanceable circuit means is unbalanced in said first direction, balanced, and unbalanced in said second direction respectively; and control means having an energizing circuit connected to said first and second bistable circuit means for varying the light falling on said photosensitive transducer means in response to said first and third digital output signals in a direction to rebalance said balanceable circuit means.
Claim 3
Dependent Claim
49 words
Apparatus as set forth in claim 1, wherein said balancable circuit means comprise a bridge circuit and a differential amplifier connected to the output of said bridge circuit for furnishing said first signal; and wherein said determined characteristic of said first signal is the amplitude of said first signal.
Claim 4
Dependent Claim
89 words
Apparatus as set forth in claim 2, wherein said first bistable circuit means comprise a bistable threshold stage adapted to change from a first to a second stable state when the amplitude of said first signal exceeds said first threshold amplitude; wherein said second bistable circuit means comprise a second bistable threshold stage adapted to change from a first to a second stable state when said amplitude of said first signal exceeds said second threshold amplitude, and an inverter connected to the output of said second bistable threshold stage.
Claim 5
Dependent Claim
59 words
Apparatus as set forth in claim 3, wherein said first and second bistable threshold stages are substantially identical stages; further comprising voltage divider means interconnected between the output of said differential amplifier and the input of said second bistable threshold stage for voltage dividing said first signal and applying a reduced first signal to said second bistable threshold stage.
Claim 6
Dependent Claim
81 words
Apparatus as set forth in claim 3, wherein said control means is energized in the presence of an energizing signal, deenergized in the absence of said energizing signal, and is operable in a first or second direction in response to the absence or presence of a direction signal respectively; further comprising logic circuit means connected to the outputs of said first and second bistable threshold stages for furnishing said energizing signal in response to said first and third digital output signals.
Claim 7
Dependent Claim
48 words
Apparatus as set forth in claim 5, wherein said logic circuit means comprise a NAND circuit having a first input connected to the output of said first bistable threshold stage, a second input connected to the output of said inverter, and an output for furnishing said energizing signal.
Claim 8
Dependent Claim
34 words
Apparatus as set forth in claim 6, further comprising means connected to said first bistable threshold circuit for furnishing said direction signal only when said first bistable threshold circuit is in said second state.
Claim 9
Dependent Claim
40 words
Apparatus as set forth in claim 7, wherein said first and second bistable threshold stage each comprise a pair of inverter stages connected in cascade and a feedback network connected from the output to the input of the so-connected stages.
Claim 10
Dependent Claim
118 words
Apparatus as set forth in claim 7, wherein said photographic apparatus is a slide projector having an objective lens and first moving means for moving said objective lens along a predetermined path in a first or second direction; wherein said photoelectric transducer means comprise a first and second light-sensitive element and illuminating means for illuminating said light-sensitive element; and wherein said control means comprise second moving means mechanically coupled to said first moving means for movement therewith, for moving said illuminating means in response to said energizing signal along a predetermined path relative to said first and second light-sensitive elements and in a first or second direction corresponding to, respectively, the absence or presence of said direction signal.
Claim 11
Dependent Claim
64 words
Apparatus as set forth in claim 9, said second moving means comprise a motor; further comprising a source of electrical energy; wherein said energizing circuit includes a relay having a relay coil connected to the output of said inverter and a pair of relay contacts closed upon energization of said relay coil and connecting said motor to said source of electrical energy when closed.
Claim 12
Dependent Claim
52 words
Apparatus as set forth in claim 10, further comprising a relay coil connected to the output of said first bistable threshold stage and a selector switch connected between said motor and said source of electrical energy for reversing the direction of current flow through said motor upon energization of said relay coil.
References Cited (Backward Citations)
US3249001A
Cited
US3430053A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-08-03 | 1980-02-02 | 1980-08-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-08-03 | 1984-02-02 | 1984-08-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-08-03 | 1988-02-02 | 1988-08-03 | $7700.00 | Window Closed / Lapsed |