US3852774A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electric shutter for single lens reflex camera
Assignee: Canon Inc
•
Filing: 1972-11-21
•
Granted: 1974-12-03
•
Expires: 1992-11-21
Abstract
Abstract In the electric shutter control disclosed, a logarithmic compression circuit compresses the output of a light measuring apparatus and stores the compressed value in a memory element such as a capacitor. A first switch apparatus that responds to initial depression of a shutter release button stops storage changes in the memory element by disconnecting the element both from the compression circuit and the light measuring apparatus. A second switch apparatus responding to further depression of the shutter button opens a short circuit across a timing capacitor at the time the shutter is opened. While the shutter is open, the timing capacitor charges through an arrangement whose resistance depends upon the value stored in the memory element. When the charge across the timing capacitor reaches a threshold value, an actuating circuit closes the shutter. According to one embodiment of the invention, the memory element in the form of a capacitor forms a feedback path for an operational amplifier. The compression circuit also forms a feedback path for the operational amplifier while the light measuring apparatus forms the input to the operational amplifier. The first switch apparatus disconnects the compression circuit and the light measuring apparatus from the operational amplifier while the capacitor remains connected to the operational amplifier. Suitable attentuating means vary the shutter operation on the basis of the sensitivity of the film in the camera and the distance to the subject, where necessary.
Inventors
- 👤 T Taguchi
- 👤 Y Lura
- 👤 Y Takishima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 03:41
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G03B7/083
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
201 words
An electric shutter, comprising light sensing means for producing an output corresponding to the light sensed, storage means coupled to said sensing means for storing electrical values on the basis of the output from said sensing means, compression means coupled to said storage means and said sensing means for logarithmically compressing the output of the sensing means so that the value stored by said storage means is a logarithmic compression of the output of said sensing means, variable timing means for opening and closing the shutter at a variable rate after initiation of the timing means, circuit means coupling said storage means to said timing means for varying the rate at which the timing means operates on the basis of the value in said storage means, first switch means coupled to said storage means for decoupling said storage means from said light sensing means and said compression means so as to cause said storage means to maintain a constant value after operation of said first switch means, and second switch means operable after said first switch means for initiating operation of said variable timing means, said storage means including an operational amplifier and capacitor in feedback connection across said operational amplifier.
Claim 2
Dependent Claim
201 words
An electric shutter, comprising light sensing means for producing an output corresponding to the light sensed, storage means coupled to said sensing means for storing electrical values on the basis of the output from said sensing means, compression means coupled to said storage means and said sensing means for logarithmically compressing the output of the sensing means so that the value stored by said storage means is a logarithmic compression of the output of said sensing means, variable timing means for opening and closing the shutter at a variable rate after initiation of the timing means, circuit means coupling said storage means to said timing means for varying the rate at which the timing means operates on the basis of the value in said storage means, first switch means coupled to said storage means for decoupling said storage means from said light sensing means and said compression means so as to cause said storage means to maintain a constant value after operation of said first switch means, and second switch means operable after said first switch means for initiating operation of said variable timing means, said storage means including an operational amplifier and capacitor in feedback connection across said operational amplifier.
Claim 3
Dependent Claim
19 words
An apparatus as in claim 1, wherein said compression means form a second feeback path across said operational amplifier.
Claim 4
Dependent Claim
63 words
An apparatus as in claim 2, wherein said light sensing means includes a photoelectric element, a pair of variable resistors establishing a variable voltage, the values of said resistors representing photographic values, a comparator between said photoelectric element and the voltage established by said resistors, and connecting means for coupling said light sensing means to said storage means through said first switch means.
Claim 5
Dependent Claim
27 words
An apparatus as in claim 2, wherein said circuit means includes input means for atenuating the value from said storage means on the basis of photographic information.
Claim 6
Dependent Claim
23 words
An apparatus as in claim 4, wherein said input means includes a resistor bridge, and a voltage source applied across said resistor bridge.
Claim 7
Dependent Claim
25 words
An apparatus as in claim 1, further comprising second switch means operable after said first switch means for initiating operation of said variable timing means.
Claim 8
Dependent Claim
224 words
An electric shutter, comprising light sensing means for producing an output corresponding to the light sensed, storage means coupled to said sensing means for storing electrical values on the basis of the output from said sensing means, compression means coupled to said storage means and said sensing means for logarithmically compressing the output of the sensing means so the valve stored by said storage means is a logarithmic compression of the output of said sensing means, variable timing means for opening and closing the shutter at a variable rate after initiation of the timing means, circuit means coupling said storage means to said timing means for varying the rate at which the timing means operates on the basis of the value in said storage means, first switch means coupled to said storage means for decoupling said storage means from said light sensing means and said compression means so as to cause said storage means to maintain a constant value after operation of said first switch means, and second switch means operable after said first switch means for initiating operation of said variable timing means said storage means including a capacitor, and a comparator circuit comparing the voltage across said capacitor with a predetermined value, and feedback means connected to the output of said comparator means and one of the inputs of said comparator means.
Claim 9
Dependent Claim
224 words
An electric shutter, comprising light sensing means for producing an output corresponding to the light sensed, storage means coupled to said sensing means for storing electrical values on the basis of the output from said sensing means, compression means coupled to said storage means and said sensing means for logarithmically compressing the output of the sensing means so the valve stored by said storage means is a logarithmic compression of the output of said sensing means, variable timing means for opening and closing the shutter at a variable rate after initiation of the timing means, circuit means coupling said storage means to said timing means for varying the rate at which the timing means operates on the basis of the value in said storage means, first switch means coupled to said storage means for decoupling said storage means from said light sensing means and said compression means so as to cause said storage means to maintain a constant value after operation of said first switch means, and second switch means operable after said first switch means for initiating operation of said variable timing means said storage means including a capacitor, and a comparator circuit comparing the voltage across said capacitor with a predetermined value, and feedback means connected to the output of said comparator means and one of the inputs of said comparator means.
Claim 10
Dependent Claim
235 words
An electric shutter, comprising light sensing means for producing an output corresponding to the light sensed, storage means coupled to said sensing means for storing electrical values on the basis of the output from said sensing means, compression means coupled to said storage means and said sensing means for logarithmically compressing the output of the sensing means so the value stored by said storage means is a logarithmic compression of the output of said sensing means, variable timing means for opening and closing the shutter at a variable rate after initiation of the timing means, circuit means coupling said storage means to said timing means for varying the rate at which the timing means operates on the basis of the value in said storage means, first switch means coupled to said storage means for decoupling said storage means from said light sensing means and said compression means so as to cause said storage means to maintain a constant value after operation of said first switch means, and second switch means operable after said first switch means for initiating operation of said variable timing means said compression means includes a plurality of cascade connected transistors, each of said transistors being in common collector connection, said light sensing means being connected in series with one of said transistors, an output transistor, and a feedback path from said output transistor to the first of said cascade connected transistors.
Claim 11
Dependent Claim
235 words
An electric shutter, comprising light sensing means for producing an output corresponding to the light sensed, storage means coupled to said sensing means for storing electrical values on the basis of the output from said sensing means, compression means coupled to said storage means and said sensing means for logarithmically compressing the output of the sensing means so the value stored by said storage means is a logarithmic compression of the output of said sensing means, variable timing means for opening and closing the shutter at a variable rate after initiation of the timing means, circuit means coupling said storage means to said timing means for varying the rate at which the timing means operates on the basis of the value in said storage means, first switch means coupled to said storage means for decoupling said storage means from said light sensing means and said compression means so as to cause said storage means to maintain a constant value after operation of said first switch means, and second switch means operable after said first switch means for initiating operation of said variable timing means said compression means includes a plurality of cascade connected transistors, each of said transistors being in common collector connection, said light sensing means being connected in series with one of said transistors, an output transistor, and a feedback path from said output transistor to the first of said cascade connected transistors.
Claim 12
Dependent Claim
27 words
An apparatus as in claim 8, wherein said compression means further includes biasing means, said biasing means including a source and potentiometer means connected across said source.
Claim 13
Dependent Claim
47 words
An apparatus as in claim 9, wherein said circuit means includes a regeneration circuit, said regeneration circuit having a plurality of cascade connected transistors, each of said transistors being in common collector connection, said timing means having a transistor forming an output transistor for said regeneration circuit.
Claim 14
Dependent Claim
25 words
An apparatus as in claim 9, wherein said potentiometer means include input means for setting values corresponding to the diaphragm aperture and the film sensitivity.
Claim 15
Dependent Claim
25 words
An apparatus as in claim 10, wherein said potentiometer means include input means for setting values corresponding to the diaphragm aperture and the film sensitivity.
Claim 16
Dependent Claim
168 words
An electric shutter comprising a light measuring circuit having a light receiving element, an operational amplifier responsive to the output of said light measuring circuit, a negative feedback circuit across said operational amplifier, a memory capacitor connected in said negative feedback circuit, a second negative feedback circuit in parallel with said capacitor and including circuit means having a resistive element, switching means for breaking the connection between said capacitor and said light measuring circuit and said first feedback circuit for stopping the change across that capacitor after a light measurement, a shutter mechanism including means for opening the shutter mechanism, a timer circuit incLuding means for initiating the operation thereof in response to opening of the shutter mechanism and responsive to said operational amplifier so as to exhibit different delay times corresponding to the memorized value of the capacitor, and closing means coupled to said shutter mechanism and responsive to said timer circuit for closing the shutter mechanism after completion of the delay time of the timer circuit.
Claim 17
Dependent Claim
168 words
An electric shutter comprising a light measuring circuit having a light receiving element, an operational amplifier responsive to the output of said light measuring circuit, a negative feedback circuit across said operational amplifier, a memory capacitor connected in said negative feedback circuit, a second negative feedback circuit in parallel with said capacitor and including circuit means having a resistive element, switching means for breaking the connection between said capacitor and said light measuring circuit and said first feedback circuit for stopping the change across that capacitor after a light measurement, a shutter mechanism including means for opening the shutter mechanism, a timer circuit incLuding means for initiating the operation thereof in response to opening of the shutter mechanism and responsive to said operational amplifier so as to exhibit different delay times corresponding to the memorized value of the capacitor, and closing means coupled to said shutter mechanism and responsive to said timer circuit for closing the shutter mechanism after completion of the delay time of the timer circuit.
Claim 18
Dependent Claim
15 words
A shutter as in claim 13 wherein said light receiving element is a photoconductive element.
Claim 19
Dependent Claim
15 words
A shutter as in claim 14, wherein said light receiving element is a photo-electromotive element.
Claim 20
Dependent Claim
23 words
A shutter as in claim 14, further comprising input means for entering photographic information between said light measuring circuit and said operational amplifier.
Claim 21
Dependent Claim
23 words
An apparatus as in claim 16, further comprising indication means coupled to said memory capacitor for indicating the value of said memory capacitor.
Claim 22
Dependent Claim
13 words
An apparatus as in claim 17, wherein said indication means is a meter.
Claim 23
Dependent Claim
17 words
A shutter as in claim 13, wherein said circuit means includes compression means having a logarithmic characteristic.
Claim 24
Dependent Claim
52 words
A shutter as in claim 19, wherein said input means includes a comparator, said comparator having a first input terminal connected to said light measuring circuit and a second input terminal, a voltage divider having a variable resistor settable to the photographic information, said second terminal being connected to said voltage divider.
Claim 25
Dependent Claim
29 words
A shutter as in claim 19, further comprising setting means resonsive to the setting of a diaphragm and film sensitivity, said variable resistor being responsive to said setting means.
Claim 26
Dependent Claim
134 words
An electric shutter, comprising light sensing means for producing an output corresponding to the light sensed, storage means coupled to said sensing means for storing electrical values on the basis of the output from said sensing means, said storage means including an operational amplifier and a capacitor in feedback connection across said operational amplifier, variable timing means responsive to said storage means for opening and closing the shutter at a variable rate after initiation of the timing means and for varying the rate at which the timing means operates on the basis of the value in said storage means, switch means coupled to said storage means for decoupling said storage means from said light sensing means so as to cause said storage means to maintain a constant value after operation of said switch means.
Claim 27
Dependent Claim
134 words
An electric shutter, comprising light sensing means for producing an output corresponding to the light sensed, storage means coupled to said sensing means for storing electrical values on the basis of the output from said sensing means, said storage means including an operational amplifier and a capacitor in feedback connection across said operational amplifier, variable timing means responsive to said storage means for opening and closing the shutter at a variable rate after initiation of the timing means and for varying the rate at which the timing means operates on the basis of the value in said storage means, switch means coupled to said storage means for decoupling said storage means from said light sensing means so as to cause said storage means to maintain a constant value after operation of said switch means.
Claim 28
Dependent Claim
31 words
An apparatus as described in claim 22, wherein said storage means further includes compressions means coupled to said capacitor and sensing means for logarithmically compressing the output of the sensing means.
Claim 29
Dependent Claim
45 words
An apparatus as in claim 22, wherein said light sensing means includes a photoelectric element, a pair of variable resistors establishing a variable voltage, the values of said registors representing photographic values, a comparator between said photoelectric element and the voltage established by said resistors.
Claim 30
Dependent Claim
38 words
An apparatus as in claim 22, further comprising circuit means for varying the rate at which the timing means operates on the basis of the value in said capacitor between said storage means and said variable timing means.
Claim 31
Dependent Claim
27 words
An apparatus as in claim 25, wherein said circuit means includes input means for attenuating the value from the storage means on the basis of photographic information.
Claim 32
Dependent Claim
23 words
An apparatus as in claim 26, wherein said input means includes a resistor bridge, and a voltage source applied across said resistor bridge.
Claim 33
Dependent Claim
14 words
An apparatus as in claim 25, wherein said circuit means include logarithmic expander circuit.
Claim 34
Dependent Claim
72 words
An apparatus as in claim 25, wherein one of said sensing means and said circuit means includes input means for establishing electrical values corresponding to photographic conditions, said input means including lever means responding to a projection of a magazine holding film to be exposed, said input means further including Alternating setting means having a pair of rods and manually operable means in the event that the magazine does not have projections.
Claim 35
Dependent Claim
18 words
An apparatus as in claim 29, wherein said input means further includes means for setting the diaphragm aperture.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-02 | 1978-06-03 | 1978-12-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-02 | 1982-06-03 | 1982-12-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-02 | 1986-06-03 | 1986-12-03 | $7700.00 | Window Closed / Lapsed |