Patent US3821552A successfully refreshed from Google Patents.
US3821552A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Circuit arrangement in particular for x ray diagnostic apparatus
Assignee: US Philips Corp
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Filing: 1972-11-02
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Granted: 1974-06-28
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Expires: 1992-11-02
Abstract
Abstract In an electronic exposure meter for an X-ray diagnostic apparatus use is made of a circuit arrangement comprising digital circuit components. This results in a higher exposure accuracy and avoids incorrect switching as well as the use of inductances and capacitances which are difficult to maintain in practice. An active filter circuit is used as an input band-rejection filter, the said circuit consisting of a band-pass filter and an adding stage which provides automatic offset correction and delaycorrection. The adding stage is followed by an interference suppression device and a positively fed back field effect transistor differentiating stage.
Inventors
- 👤 B Hermeyer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 03:50
CPC Classifications
H; H05; H05G; H05G1/00; H05G1/08; H05G1/26; H05G1/30; H05G1/38; H05G1/42; H05G1/44
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
204 words
A signal processing circuit for an automatic exposure device that includes a radiation detector coupled to an electrotransmitter amplifier and including means for suppressing interference signals comprising, a low pass filter adapted to receive the signal to be processed and any interference signals that occur, a band-pass filter constructed as an active filter circuit with its input coupled to the output of the low pass filter, an adding stage with means for providing automatic offset correction and delay correction, means for coupling the output of the low pass filter and the band-pass filter output to the input circuit of said adding stage, a comparison stage including a positive feedback field effect transistor differentiating circuit with one input coupled to a source of reference voltage and a second input coupled to the output of the adding stage, interference suppression means having an output coupled to the input of the comparison stage and an input coupled to the output of the adding stage and responsive to interference signals appearing thereat to become operative to effectively block said interference signals from affecting the comparison stage, and an output stage coupled to the output of the comparison stage for deriving an output signal for terminating an exposure period.
Claim 2
Dependent Claim
204 words
A signal processing circuit for an automatic exposure device that includes a radiation detector coupled to an electrotransmitter amplifier and including means for suppressing interference signals comprising, a low pass filter adapted to receive the signal to be processed and any interference signals that occur, a band-pass filter constructed as an active filter circuit with its input coupled to the output of the low pass filter, an adding stage with means for providing automatic offset correction and delay correction, means for coupling the output of the low pass filter and the band-pass filter output to the input circuit of said adding stage, a comparison stage including a positive feedback field effect transistor differentiating circuit with one input coupled to a source of reference voltage and a second input coupled to the output of the adding stage, interference suppression means having an output coupled to the input of the comparison stage and an input coupled to the output of the adding stage and responsive to interference signals appearing thereat to become operative to effectively block said interference signals from affecting the comparison stage, and an output stage coupled to the output of the comparison stage for deriving an output signal for terminating an exposure period.
Claim 3
Dependent Claim
33 words
A circuit for an automatic exposure device as claimed in claim 1, characterizEd in that the low-pass filter is constructed as an active filter for the suppression of interference signals above 500 Hz.
Claim 4
Dependent Claim
52 words
A circuit for an automatic exposure device as claimed in claim 1, characterized in that the active filter circuit of the band-pass filter comprises three operational amplifiers in cascade which represent an analog calculating circuit for simulating the normal oscillatory circuit, each amplifier comprising only one adjusting member for one resonant frequency.
Claim 5
Dependent Claim
86 words
A circuit for an automatic exposure device as claimed in claim 1, characterized in that a ripple signal which is supplied to the band-pass filter circuit is phase-shifted 180 and is supplied to the adding stage to be added to the input signal so as to eliminate any ripple in the input signal, the offset correction being achieved by means for the suppression of the direct current component and the delay-correction being produced by an RC element connected in a feedback line of the adding stage.
Claim 6
Dependent Claim
196 words
A radiation detection system comprising, a radiation detector responsive to the radiation for deriving an electric signal determined thereby, a low pass filter, means for coupling an amplified version of said electric signal to the input of the low pass filter, signal adding means, a band-pass filter with an input connected to the output of the low pass filter and an output coupled to the input circuit of the adding means, said band-pass filter including means for providing a 180* phase-shift for given signals passing therethrough, means for coupling the signal at the output of the low pass filter to said input circuit of the adding means, a comparison stage including a positive feedback field effect transistor differentiating circuit with an input coupled to the output of the adding means and an output for supplying a control signal to control the operating period of the system, and electric interference suppression means coupled to the output of the adding means and to the input of the comparison stage and operative in response to an interference signal at the output of the adding means to effectively suppress said interference signal from affecting the input of the comparison stage.
Claim 7
Dependent Claim
196 words
A radiation detection system comprising, a radiation detector responsive to the radiation for deriving an electric signal determined thereby, a low pass filter, means for coupling an amplified version of said electric signal to the input of the low pass filter, signal adding means, a band-pass filter with an input connected to the output of the low pass filter and an output coupled to the input circuit of the adding means, said band-pass filter including means for providing a 180* phase-shift for given signals passing therethrough, means for coupling the signal at the output of the low pass filter to said input circuit of the adding means, a comparison stage including a positive feedback field effect transistor differentiating circuit with an input coupled to the output of the adding means and an output for supplying a control signal to control the operating period of the system, and electric interference suppression means coupled to the output of the adding means and to the input of the comparison stage and operative in response to an interference signal at the output of the adding means to effectively suppress said interference signal from affecting the input of the comparison stage.
Claim 8
Dependent Claim
37 words
A system as claimed in claim 5 wherein said adding means further comprises, amplifier means including means for providing offset correction and an RC circuit connected to a feedback circuit of the amplifier means to provide relay-correction.
Claim 9
Dependent Claim
28 words
A system as claimed in claim 5 wherein said band-pass filter comprises an active filter circuit that includes an operational amplifier arranged to simulate the normal resonant circuit.
Claim 10
Dependent Claim
40 words
A system as claimed in claim 5 further comprising an AC supply for the system and wherein said band-pass filter comprises an active filter circuit that includes an operational amplifier and tuned to a harmonic of the AC supply frequency.
Claim 11
Dependent Claim
37 words
A system as claimed in claim 5 wherein said interference suppression means comprises a switching circuit in shunt with the input of the comparison stage for shunting interference signals away from the input of the comparison stage.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-27 | 1977-12-27 | 1978-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-27 | 1981-12-27 | 1982-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-27 | 1985-12-27 | 1986-06-28 | $7700.00 | Window Closed / Lapsed |