Patent US3767939A successfully refreshed from Google Patents.
US3767939A
Expired / Lapsed
US
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Dynamic filter
Assignee: Applied Biosystems Inc
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Filing: 1971-12-29
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Granted: 1973-10-23
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Expires: 1991-12-29
Abstract
Abstract The disclosure describes a system for automatically controlling the time constant of an electronic filter to significantly alter the transition time from one signal response level to another. The system employs a variable impedance means, such as a field effect transistor, which can alter the effective time constant of the filter. Sensor means sample the imput signal to the filter and produce a control signal in response to an amount and rate of change in the input signal greater than a predetermined value. Control means, such as a polarity changing inverter and a diode gating network, energize the field effect transistor in response to either polarity of the control signal, so that the time constant of the filter is changed.
Inventors
- 👤 M Chamran
- 👤 S Pak
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:33
CPC Classifications
H; H03; H03G; H03G5/00; H03G5/16; H03G5/18; H03H; H03H11/00; H03H11/02; H03H11/04; H03H11/0405
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
112 words
In a system comprising a filter having an input terminal adapted to receive an input signal and an output terminal, improved apparaTus for changing the time constant of the filter comprising: variable impedance means connected to the filter; sensor means for producing a control signal in response to a change or rate of change in the amplitude of the input signal greater than a predetermined value, the control signal being produced only during said change or rate of change in the amplitude greater than the predetermined value ; and control means for energizing the variable impedance means in response to the control signal, whereby the time constant of the filter is changed.
Claim 2
Dependent Claim
112 words
In a system comprising a filter having an input terminal adapted to receive an input signal and an output terminal, improved apparaTus for changing the time constant of the filter comprising: variable impedance means connected to the filter; sensor means for producing a control signal in response to a change or rate of change in the amplitude of the input signal greater than a predetermined value, the control signal being produced only during said change or rate of change in the amplitude greater than the predetermined value ; and control means for energizing the variable impedance means in response to the control signal, whereby the time constant of the filter is changed.
Claim 3
Dependent Claim
15 words
Apparatus, as claimed in claim 1, wherein the variable impedance means comprises field effect transistor.
Claim 4
Dependent Claim
17 words
Apparatus, as claimed in claim 1, wherein the sensor means comprises means for differentiating the input signal.
Claim 5
Dependent Claim
38 words
Apparatus, as claimed in claim 1, wherein the control means comprises: means for inverting the control signal to produce an inverted signal; and gating means for producing a gating signal in response to the inverted and control signals.
Claim 6
Dependent Claim
137 words
In a system comprising a filter having an input terminal adapted to receive an input signal and also having an output terminal, improved apparatus for changing the time constant of the filter comprising: variable impedance means connected to the filter; sensor means for producing a control signal in response to a change or rate of change in the input signal greater than a predetermined value; control means for energizing the variable impedance means in response to the control signal, whereby the time constant of the filter is changed; means for generating a sampling signal corresponding to a component of the input signal having a predetermined phase and frequency; means for coacting the sampling signal with the input signal to extract said component from the input signal; and means for transmitting the extracted signal to the sensor means.
Claim 7
Dependent Claim
137 words
In a system comprising a filter having an input terminal adapted to receive an input signal and also having an output terminal, improved apparatus for changing the time constant of the filter comprising: variable impedance means connected to the filter; sensor means for producing a control signal in response to a change or rate of change in the input signal greater than a predetermined value; control means for energizing the variable impedance means in response to the control signal, whereby the time constant of the filter is changed; means for generating a sampling signal corresponding to a component of the input signal having a predetermined phase and frequency; means for coacting the sampling signal with the input signal to extract said component from the input signal; and means for transmitting the extracted signal to the sensor means.
Claim 8
Dependent Claim
62 words
Apparatus, as claimed in claim 5, wherein the means for coacting comprises: a pulse forming means driven by the means for generating for producing a pulse signal; and a gating device having at least a first terminal responsive to the pulse signal, a second terminal responsive to the input signal, and a third terminal connected to a capacitor and the sensor means.
Claim 9
Independent Claim
201 words
A system for filtering in input signal comprising: filter means for filtering the input signal to produce a filtered output signal; an input signal path for conducting the input signal to the filter means; an output signal path for conducting the output signal away from the filter means; variable impedance means connected to the filter means for producing a first impedance in response to a first energizing signal so that the filter means has a first time constant and for producing a second impedance different from the first impedance in response to a second energizing signal so that the filter means has a second time constant; and sensor control means operatively connected between the input signal path and the variable impedance means for normally transmitting the first energizing signal to the variable impedance means so that the filter has the first time constant and for transmitting the second energizing signal to the variable impedance means only during an input signal change exceeding a predetermined magnitude and having a rate of change within a predetermined range of values, so that the filter switches to the second time constant only during said input signal change, and thereafter reverts to the first time constant.
Claim 10
Independent Claim
201 words
A system for filtering in input signal comprising: filter means for filtering the input signal to produce a filtered output signal; an input signal path for conducting the input signal to the filter means; an output signal path for conducting the output signal away from the filter means; variable impedance means connected to the filter means for producing a first impedance in response to a first energizing signal so that the filter means has a first time constant and for producing a second impedance different from the first impedance in response to a second energizing signal so that the filter means has a second time constant; and sensor control means operatively connected between the input signal path and the variable impedance means for normally transmitting the first energizing signal to the variable impedance means so that the filter has the first time constant and for transmitting the second energizing signal to the variable impedance means only during an input signal change exceeding a predetermined magnitude and having a rate of change within a predetermined range of values, so that the filter switches to the second time constant only during said input signal change, and thereafter reverts to the first time constant.
Claim 11
Dependent Claim
29 words
Apparatus, as claimed in claim 7, wherein the variable impedance means comprises a field effect transistor having a gate to which the first and second energizing signals are transmitted.
Claim 12
Dependent Claim
18 words
Apparatus, as claimed in claim 7, wherein the sensor control means comprises means for differentiating the input signal.
Claim 13
Dependent Claim
20 words
Apparatus, as claimed in claim 7, wherein the sensor control means is connected in parallel with the input signal path.
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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) | 1976-10-22 | 1977-04-23 | 1977-10-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-22 | 1981-04-23 | 1981-10-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-22 | 1985-04-23 | 1985-10-23 | $7700.00 | Window Closed / Lapsed |