US3906389A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Difference amplifier with gain controlled by the sum of the inputs
Assignee: Canon Inc
•
Filing: 1973-03-26
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Granted: 1975-09-16
•
Expires: 1993-03-26
Abstract
Abstract A comparator circuit comprising an amplifier having its input fed as a difference of a pair of inputs and whose gain is controlled by a control signal corresponding to the sum of the pair of inputs so as to provide an amplifier output which is stabilized over a large range of input variation.
Inventors
- 👤 Seiichi Matsumoto
- 👤 Kazuya Hosoe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:29
CPC Classifications
G; G02; G02B; G02B7/00; G02B7/28; G02B7/30; G02B7/32
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
119 words
In a comparator circuit: first light sensitive means comprising first and second photoelectric elements; first means for detecting the difference between the outputs of the first and second photoelectric elements of the first light sensitive means; second means for detecting the sum of the outputs of the first and second photoelectric elements of the first light sensitive means; variable-gain amplifier means; means for coupling the output of the first detecting means to the input of the variable-gain amplifier means; and means responsive to the output of the second detecting means for varying the gain of the variable-gain amplifier means by an amount determined by, and in a direction opposite from variations in the output of the second detecting means.
Claim 2
Dependent Claim
119 words
In a comparator circuit: first light sensitive means comprising first and second photoelectric elements; first means for detecting the difference between the outputs of the first and second photoelectric elements of the first light sensitive means; second means for detecting the sum of the outputs of the first and second photoelectric elements of the first light sensitive means; variable-gain amplifier means; means for coupling the output of the first detecting means to the input of the variable-gain amplifier means; and means responsive to the output of the second detecting means for varying the gain of the variable-gain amplifier means by an amount determined by, and in a direction opposite from variations in the output of the second detecting means.
Claim 3
Dependent Claim
36 words
A comparator circuit according to claim 1, in which the first detecting means comprises a differential network having a pair of input terminals connected to the respective output terminals of the first and second photoelectric elements.
Claim 4
Dependent Claim
16 words
A comparator circuit according to claim 2, in which the differential network is an operational amplifier.
Claim 5
Dependent Claim
81 words
A comparator circuit according to claim 1, in which the variable-gain amplifier means comprises, in combination, an operational amplifier having first and second inputs; means for connecting the output of the first detecting means to one input of the operational amplifier; and means including a third photoelectric element for connecting the output of the operational amplifier to the other input thereof for varying the amplification of the operational amplifier in accordance with variations in the resistance of the third photoelectric element.
Claim 6
Dependent Claim
60 words
A comparator circuit according to claim 4, in which the amplitude varying means comprises, in combination, luminous means disposed in irradiating relation to the third photoelectric element; and means for coupling the output of the second detecting means to the luminous means for varying the illumination of the luminous means to correspondingly vary the resistance of the third photoelectric element.
Claim 7
Dependent Claim
15 words
A comparator circuit according to claim 4, in which the luminous means is a lamp.
References Cited (Backward Citations)
US3497717A
Cited
US3610934A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-15 | 1979-03-17 | 1979-09-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-15 | 1983-03-17 | 1983-09-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-15 | 1987-03-17 | 1987-09-16 | $7700.00 | Window Closed / Lapsed |