GB2169720A - Detecting rate of change of signals - Google Patents

Detecting rate of change of signals Download PDF

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Publication number
GB2169720A
GB2169720A GB08600555A GB8600555A GB2169720A GB 2169720 A GB2169720 A GB 2169720A GB 08600555 A GB08600555 A GB 08600555A GB 8600555 A GB8600555 A GB 8600555A GB 2169720 A GB2169720 A GB 2169720A
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GB
United Kingdom
Prior art keywords
sample
circuit
signal
input
change
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB08600555A
Other versions
GB8600555D0 (en
Inventor
Ronald Coates-Smith
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BROWNELL Ltd
Original Assignee
BROWNELL Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by BROWNELL Ltd filed Critical BROWNELL Ltd
Publication of GB8600555D0 publication Critical patent/GB8600555D0/en
Publication of GB2169720A publication Critical patent/GB2169720A/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/12—Measuring rate of change
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M3/00—Investigating fluid-tightness of structures
    • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
    • G01M3/26—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Examining Or Testing Airtightness (AREA)

Abstract

An input signal, e.g. from a bridge pressure transducer 1, is fed to one input (6) of a comparator (7) and also to the input (8) of sample and hold circuit (9), the output of which feeds the other input (10) of the comparator (7). The output of comparator (7) is fed to a second sample and hold circuit (11), and the signal therefrom is fed through a buffer amplifier (12) to a display (13). A control circuit (14) feeds timing signals to each sample and hold circuit (9 and 11) to cause them to capture the respective values of the input signal present at a predetermined time interval, and also the comparator output signal, the latter representing the rate of change of the input. <IMAGE>

Description

SPECIFICATION Leak rate detector circuit This invention relates to a detector circuit means for indicating and measuring a rate of change, such as pressure, wherein the change rate is a measure of the leakage. Such a device may be used in association with a pressure transducer in a container to indicate any pressure escape therefrom.
An object of this invention is to provide a circuit means capable of high accuracy but of simple construction and which enables very smail rates of change to be measured.
According to this invention there is provided a detector means for measuring a rate of change in an input signal, the means comprising a sample and hold circuit fed with the input signal, the output of the sample and hold circuit being fed to one input of a comparator the other input of the comparator being fed with the input signal, a control circuit operative to capture a signal value in the sample and hold circuit, the difference between said sample signal and the input signal detected by the comparator circuit at any instant being used to provide an output signal indicating the rate of change in the input signal.
The output of the comparator preferably feeds a second sample and hold circuit to provide an output signal, the second sample and hold circuit being operatively connected with the control circuit.
The control circuit preferably comprises a timing clock to issue a logic controlling signal at predetermined intervals to define the interval over which the rate of change is determined.
One embodiment of a circuit in accordance with this invention is shown by way of example in the accompanying drawing.
As shown in the drawing a bridge-type pressure transducer 1 feeds a signal to a bridge amplifier 2 coupled through a zero-set device 3 with an input amplifier 4, the output of which constitutes an input signal for the rate of change measuring the circuit following.
The gain of amplifier 4 is set by feedback resistor 5. The input signal is fed to one input 6 of a comparator 7 and to the input 8 of sample and hold circuit 9, the output of which feeds the other input 10 of the comparator 7.
The output of comparator 7 is fed to a second sample and hold circuit 11 through a buffer amplifier 12 to a display 13. A control circuit 14 feeds signals to each sample and hold circuit 9 and 11 to capture the value of input signal present at a predetermined time interval, and also the comparator output signal.
The circuit operates as follows: At the start of a timing cycle a sample is taken in circuit 9 of the pressure input signal after a suitably defined time delay, the difference between the captured sampled signal in circuit 9 and the actual input signal present is sampled by the output sample and hold circuit 11 and used to give a meter readout on the display 13 of the actual pressure change. The cycle then restarts thus providing a continuous update effected by control circuit 14. In this way a readout is presented which corresponds to pressure change over a given time, (for example pascals/min.). If the pressure source is a container under pressure then the pressure change would correspond to any escape of pressure from the container, that is the leak rate.
The device provides a simple circuit having high accuracy particularly suited to determining the presence of any contaminant gases in a chamber introduced through leakage.
In this invention, therefore, there is provided a detector circuit by which the rate of change of an electrical signal may be measured and indicated. For a specific application the signal from a pressure transducer reacting to changing pressure, either differential, gauge or absolute, may be utilised to give a read-out indicating the rate of such change. (This might be used to establish the rate of pressure loss from a sealed container via an umbilical pipe).
The advantage of the circuit described is that the actual pressure change over a preselected time interval is separate from the absolute or gauge pressure before amplifying and passing to the sample and hold l.C.S. for measurement.
The signal is then measured at the beginning of a time interval and the reading stored and passed to a linear amplifier/buffer stage.
The signal is also passed continuously to the other input of the buffer stage at the end of the time interval and the instantaneous output of this buffer is then "read" by a second sample and hold circuit and passed via a suitable buffer stage to the output display.
The entire sequence is repeated at the end of the selected suitable time sequence.
1. A detector means for measuring a rate of change in an input signal, the means comprising a sample and hold circuit fed with the input signal, the output of the sample and hold circuit being fed to one input of a comparator the other input of the comparator being fed with the input signal, a control circuit operative to capture a signal value in the sample and hold circuit, the difference between said sample signal and the input signal detected by the comparator circuit at any instant being used to provide an output signal indicating the rate of change in the input signal.
2. A detector means in accordance with Claims 1, wherein the output of the comparator feeds a second sample and hold circuit to provide an output signal, the second sample and hold circuit being operatively connected
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Leak rate detector circuit This invention relates to a detector circuit means for indicating and measuring a rate of change, such as pressure, wherein the change rate is a measure of the leakage. Such a device may be used in association with a pressure transducer in a container to indicate any pressure escape therefrom. An object of this invention is to provide a circuit means capable of high accuracy but of simple construction and which enables very smail rates of change to be measured. According to this invention there is provided a detector means for measuring a rate of change in an input signal, the means comprising a sample and hold circuit fed with the input signal, the output of the sample and hold circuit being fed to one input of a comparator the other input of the comparator being fed with the input signal, a control circuit operative to capture a signal value in the sample and hold circuit, the difference between said sample signal and the input signal detected by the comparator circuit at any instant being used to provide an output signal indicating the rate of change in the input signal. The output of the comparator preferably feeds a second sample and hold circuit to provide an output signal, the second sample and hold circuit being operatively connected with the control circuit. The control circuit preferably comprises a timing clock to issue a logic controlling signal at predetermined intervals to define the interval over which the rate of change is determined. One embodiment of a circuit in accordance with this invention is shown by way of example in the accompanying drawing. As shown in the drawing a bridge-type pressure transducer 1 feeds a signal to a bridge amplifier 2 coupled through a zero-set device 3 with an input amplifier 4, the output of which constitutes an input signal for the rate of change measuring the circuit following. The gain of amplifier 4 is set by feedback resistor 5. The input signal is fed to one input 6 of a comparator 7 and to the input 8 of sample and hold circuit 9, the output of which feeds the other input 10 of the comparator 7. The output of comparator 7 is fed to a second sample and hold circuit 11 through a buffer amplifier 12 to a display 13. A control circuit 14 feeds signals to each sample and hold circuit 9 and 11 to capture the value of input signal present at a predetermined time interval, and also the comparator output signal. The circuit operates as follows: At the start of a timing cycle a sample is taken in circuit 9 of the pressure input signal after a suitably defined time delay, the difference between the captured sampled signal in circuit 9 and the actual input signal present is sampled by the output sample and hold circuit 11 and used to give a meter readout on the display 13 of the actual pressure change. The cycle then restarts thus providing a continuous update effected by control circuit 14. In this way a readout is presented which corresponds to pressure change over a given time, (for example pascals/min.). If the pressure source is a container under pressure then the pressure change would correspond to any escape of pressure from the container, that is the leak rate. The device provides a simple circuit having high accuracy particularly suited to determining the presence of any contaminant gases in a chamber introduced through leakage. In this invention, therefore, there is provided a detector circuit by which the rate of change of an electrical signal may be measured and indicated. For a specific application the signal from a pressure transducer reacting to changing pressure, either differential, gauge or absolute, may be utilised to give a read-out indicating the rate of such change. (This might be used to establish the rate of pressure loss from a sealed container via an umbilical pipe). The advantage of the circuit described is that the actual pressure change over a preselected time interval is separate from the absolute or gauge pressure before amplifying and passing to the sample and hold l.C.S. for measurement. The signal is then measured at the beginning of a time interval and the reading stored and passed to a linear amplifier/buffer stage. The signal is also passed continuously to the other input of the buffer stage at the end of the time interval and the instantaneous output of this buffer is then "read" by a second sample and hold circuit and passed via a suitable buffer stage to the output display. The entire sequence is repeated at the end of the selected suitable time sequence. CLAIMS
1. A detector means for measuring a rate of change in an input signal, the means comprising a sample and hold circuit fed with the input signal, the output of the sample and hold circuit being fed to one input of a comparator the other input of the comparator being fed with the input signal, a control circuit operative to capture a signal value in the sample and hold circuit, the difference between said sample signal and the input signal detected by the comparator circuit at any instant being used to provide an output signal indicating the rate of change in the input signal.
2. A detector means in accordance with Claims 1, wherein the output of the comparator feeds a second sample and hold circuit to provide an output signal, the second sample and hold circuit being operatively connected with the control circuit.
3 A detector means in accordance with Claims I or 2, wherein the control circuit comprises à timing clock to issue a logic con trolling signal at predetermined intervals to de fine the interval over which the rate of change is determined.
4. A detector means as described herein and exemplified with reference to the drawing.
GB08600555A 1985-01-10 1986-01-10 Detecting rate of change of signals Withdrawn GB2169720A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB858500595A GB8500595D0 (en) 1985-01-10 1985-01-10 Leak rate detector circuit

Publications (2)

Publication Number Publication Date
GB8600555D0 GB8600555D0 (en) 1986-02-19
GB2169720A true GB2169720A (en) 1986-07-16

Family

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Family Applications (2)

Application Number Title Priority Date Filing Date
GB858500595A Pending GB8500595D0 (en) 1985-01-10 1985-01-10 Leak rate detector circuit
GB08600555A Withdrawn GB2169720A (en) 1985-01-10 1986-01-10 Detecting rate of change of signals

Family Applications Before (1)

Application Number Title Priority Date Filing Date
GB858500595A Pending GB8500595D0 (en) 1985-01-10 1985-01-10 Leak rate detector circuit

Country Status (1)

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GB (2) GB8500595D0 (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0328066A2 (en) * 1988-02-09 1989-08-16 Mitsubishi Jukogyo Kabushiki Kaisha Method of detecting noise disappearance and detecting device therefor
EP0513955A2 (en) * 1991-05-15 1992-11-19 SCHLEICHER GMBH &amp; CO. RELAIS-WERKE KG Device for intermittently measuring a quantity over a long period of time
EP0577994B1 (en) * 1992-06-25 1997-05-21 Motorola, Inc. Alternator voltage regulator comprising an alternator rotation detector and alternator battery charging system
EP0869332A2 (en) * 1997-04-02 1998-10-07 Steinel GmbH &amp; Co. KG Method and device to process a voltage signal of a sensor
EP1798839A3 (en) * 2005-12-19 2007-11-14 Samsung SDI Co., Ltd. Battery management system and method

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1345720A (en) * 1970-11-17 1974-02-06 Instrumentation Specialties Co Apparatus for correction of electrical signals having drifting base lines
GB1445398A (en) * 1972-09-20 1976-08-11 Akro Medic Eng Inc Baseline correction circuit
GB1456737A (en) * 1973-04-17 1976-11-24 Aerospatiale Device for monitoring the charging current for a battery of storage accumulators
GB1478810A (en) * 1975-11-20 1977-07-06 Standard Telephones Cables Ltd Detection circuits for monitoring current changes
GB1587664A (en) * 1976-06-29 1981-04-08 Perkin Elmer Corp Electrical output peak detecting apparatus
GB2085599A (en) * 1980-09-30 1982-04-28 Gould Advance Ltd Automatic drift correction

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1345720A (en) * 1970-11-17 1974-02-06 Instrumentation Specialties Co Apparatus for correction of electrical signals having drifting base lines
GB1445398A (en) * 1972-09-20 1976-08-11 Akro Medic Eng Inc Baseline correction circuit
GB1456737A (en) * 1973-04-17 1976-11-24 Aerospatiale Device for monitoring the charging current for a battery of storage accumulators
GB1478810A (en) * 1975-11-20 1977-07-06 Standard Telephones Cables Ltd Detection circuits for monitoring current changes
GB1587664A (en) * 1976-06-29 1981-04-08 Perkin Elmer Corp Electrical output peak detecting apparatus
GB2085599A (en) * 1980-09-30 1982-04-28 Gould Advance Ltd Automatic drift correction

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0328066A2 (en) * 1988-02-09 1989-08-16 Mitsubishi Jukogyo Kabushiki Kaisha Method of detecting noise disappearance and detecting device therefor
EP0328066A3 (en) * 1988-02-09 1990-05-02 Mitsubishi Jukogyo Kabushiki Kaisha Method of detecting noise disappearance and detecting device therefor
EP0513955A2 (en) * 1991-05-15 1992-11-19 SCHLEICHER GMBH &amp; CO. RELAIS-WERKE KG Device for intermittently measuring a quantity over a long period of time
EP0513955A3 (en) * 1991-05-15 1994-05-11 Schleicher Relais Device for intermittently measuring a quantity over a long period of time
EP0577994B1 (en) * 1992-06-25 1997-05-21 Motorola, Inc. Alternator voltage regulator comprising an alternator rotation detector and alternator battery charging system
EP0869332A2 (en) * 1997-04-02 1998-10-07 Steinel GmbH &amp; Co. KG Method and device to process a voltage signal of a sensor
EP0869332A3 (en) * 1997-04-02 1999-01-27 Steinel GmbH &amp; Co. KG Method and device to process a voltage signal of a sensor
EP1798839A3 (en) * 2005-12-19 2007-11-14 Samsung SDI Co., Ltd. Battery management system and method
US8004249B2 (en) 2005-12-19 2011-08-23 Samsung Sdi Co., Ltd. Battery management system and method

Also Published As

Publication number Publication date
GB8600555D0 (en) 1986-02-19
GB8500595D0 (en) 1985-02-13

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)