US3702447A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electronic chopper system for use in facsimile communication comprising means for alternately grounding and ungrounding inputs of amplifier
Assignee: Xerox Corp
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Filing: 1968-07-01
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Granted: 1972-11-07
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Expires: 1988-07-01
Abstract
Abstract An electronic chopper circuit for use in converting variable amplitude direct current signals to pulsed signals of similar characteristics. In conjunction with a facsimile scanning system, the modulated electrical signals generated by a photoelectric cell are applied to a differential amplifier after periodic interruption by the electronic chopping circuit in accordance with an input clock signal. The periodic interruption to the differential amplifier is provided by a dual emitter transistor which alternately grounds and ungrounds the input to the differential amplifier in response to an input clock signal. The gain of the differential amplifier is controlled by a field effect transistor which is operated as a variable resistor in response to a control voltage generated in response to the background level detected on a document. The output therefrom is a series of signal pulses, the heights of which are in direct relation to the level of the input signals.
Inventors
- 👤 Virgil H Koning
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 18:56
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/00095
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
111 words
An electronic chopping system comprising: means for generating a first electric signal of varying amplitude, amplifier means Coupled to said generating means for amplifying said first electric signal, pulse generating means coupled to the input of said amplifier for generating pulses of predetermined duration and frequency, said pulses alternately grounding and ungrounding the input to said amplifier means, whereby the output of said amplifier means comprises varying amplitude pulses in direct relation to said first electric signal of varying amplitude, and circuit means coupled to the output of said amplifier means and responsive to a control voltage to change the load impedance of said amplifier means for controlling the gain thereof.
Claim 2
Dependent Claim
111 words
An electronic chopping system comprising: means for generating a first electric signal of varying amplitude, amplifier means Coupled to said generating means for amplifying said first electric signal, pulse generating means coupled to the input of said amplifier for generating pulses of predetermined duration and frequency, said pulses alternately grounding and ungrounding the input to said amplifier means, whereby the output of said amplifier means comprises varying amplitude pulses in direct relation to said first electric signal of varying amplitude, and circuit means coupled to the output of said amplifier means and responsive to a control voltage to change the load impedance of said amplifier means for controlling the gain thereof.
Claim 3
Dependent Claim
35 words
The electronic chopping system as set forth in claim 1 wherein said first electric signal generating means comprises a photocell for receiving information modulated light beams indicative of information on a document or the like.
Claim 4
Dependent Claim
31 words
The electronic chopping system as set forth in claim 2 wherein said amplifier means comprises a differential amplifier with first and second inputs, said photocell being coupled to said first input.
Claim 5
Dependent Claim
42 words
The electronic chopping system as set forth in claim 3 further including a second photocell coupled to the second input to said amplifier means for providing temperature compensation, said second photocell being prevented from receiving any beams of said information modulated light.
Claim 6
Dependent Claim
118 words
In a facsimile transmission system including optical scanning means for scanning a document or the like with a beam of light, an electronic chopping system comprising: photodetection means for receiving the information modulated light from said document or the like and generating an electrical signal in accordance therewith, differential amplifier means with first and second inputs coupled to said photodetection means at said first input thereof for amplifying said electrical signal, and pulse generating means coupled to said first and second inputs of said differential amplifier means for alternately grounding and ungrounding the inputs to said differential amplifier means, the output of said differential amplifier means being amplified pulses in direct relation to the electrical signal applied thereto.
Claim 7
Dependent Claim
118 words
In a facsimile transmission system including optical scanning means for scanning a document or the like with a beam of light, an electronic chopping system comprising: photodetection means for receiving the information modulated light from said document or the like and generating an electrical signal in accordance therewith, differential amplifier means with first and second inputs coupled to said photodetection means at said first input thereof for amplifying said electrical signal, and pulse generating means coupled to said first and second inputs of said differential amplifier means for alternately grounding and ungrounding the inputs to said differential amplifier means, the output of said differential amplifier means being amplified pulses in direct relation to the electrical signal applied thereto.
Claim 8
Dependent Claim
58 words
The electronic chopping system as set forth in claim 5 further including means coupled to said photodetection means for generating a control voltage indicative of the background level on said document or the like, said control voltage being applied to said differential amplifier means to control the gain thereof in proportion to the background level on said document.
Claim 9
Dependent Claim
40 words
The electronic chopping system as set forth in claim 6 further including a second photodetection means coupled to the second input of said differential amplifier means for providing stabilization due to temperature change effects on said first mentioned photodetection means.
Claim 10
Dependent Claim
30 words
The electronic chopping system as set forth in claim 7 wherein said pulse generating means comprises a dual emitter transistor responsive to a clock signal of predetermined duration and frequency.
Claim 11
Dependent Claim
53 words
The electronic chopping system as set forth in claim 8 further including a field effect transistor coupled to the output of said differential amplifier means and responsive to said control voltage generated in accordance with the background level to change the load impedance of said differential amplifier means for controlling the gain thereof.
Claim 12
Dependent Claim
81 words
The electronic chopping system as set forth in claim 6 wherein said control voltage generating means comprises a peak detection means for detecting the peak amplitude signal generated by said photodetection means and generating a control voltage in direct relation to the difference between the detected peak amplitude signal and the maximum amplitude signal capable of being generated by said photodetection means, said maximum amplitude signal being generated when the background on said document or the like is detected as white.
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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) | 1975-11-07 | 1976-05-08 | 1976-11-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-11-07 | 1980-05-08 | 1980-11-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-11-07 | 1984-05-08 | 1984-11-07 | $7700.00 | Window Closed / Lapsed |