US3845388A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Rms converter
Assignee: Gemalto Terminals Ltd
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Filing: 1973-07-30
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Granted: 1974-10-29
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Expires: 1993-07-30
Abstract
Abstract An RMS converter for measuring the RMS value of an input signal. The converter comprises a bridge made up of four identical resistors whose resistance varies approximately linearly with temperature. A first heating element is in thermal contact with the resistors of two electrically-opposed arms of the bridge and is arranged to receive the input signal to be measured. A second identical heating element is in thermal contact with the resistors of the other two electrically-opposed arms of the bridge. An integrator is connected to receive the voltage across the output diagonal of the bridge and is adapted to produce the time integral of the bridge output voltage divided by time. The output of this integrator is connected to the second heating element. Means are provided for supplying the supply diagonal of the bridge with a voltage that is inversely proportional to the output voltage of the integrator, whereby the output voltage of the integrator represents the RMS value of the input signal.
Inventors
- 👤 A Ley
- 👤 H Dorey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 21:32
CPC Classifications
G; G01; G01R; G01R19/00; G01R19/02; G01R19/22; G01R19/225
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
255 words
A device for measuring the RMS value of an input signal comprising a bridge circuit having supply terminals at two corners thereof, output terminals at the opposite corners thereof and a resistive temperature sensor in each of two arms adjacent one of said supply terminals, said sensor having a resistance which varies substantially linearly with temperature; first heating element means in thermal contact with one of said sensors for receiving the input signal to be measured and for heating said one of said sensors; second heating element means having characteristics substantially identical to said first heating means, said second means being in thermal contact with the other one of said sensors for receiving a feedback signal and for heating said other one of said sensors; integrating circuit means connected to said output terminals of said bridge for accepting the electrical output signal produced by unbalance of said bridge and for producing an electrical signal representative of the time integral of said output signal divided by time; circuit means for feeding the output of said integrating circuit means back to said second heating element means; a source of voltage; and supply circuit means connected to said source of voltage, to the output of said integrating circuit means and to the supply terminals of said bridge for providing to said bridge a supply voltage which is inversely proportional to the output voltage of said integrating means, whereby the output voltage of said integrating circuit means has a magnitude representative of the RMS value of the input signal.
Claim 2
Independent Claim
255 words
A device for measuring the RMS value of an input signal comprising a bridge circuit having supply terminals at two corners thereof, output terminals at the opposite corners thereof and a resistive temperature sensor in each of two arms adjacent one of said supply terminals, said sensor having a resistance which varies substantially linearly with temperature; first heating element means in thermal contact with one of said sensors for receiving the input signal to be measured and for heating said one of said sensors; second heating element means having characteristics substantially identical to said first heating means, said second means being in thermal contact with the other one of said sensors for receiving a feedback signal and for heating said other one of said sensors; integrating circuit means connected to said output terminals of said bridge for accepting the electrical output signal produced by unbalance of said bridge and for producing an electrical signal representative of the time integral of said output signal divided by time; circuit means for feeding the output of said integrating circuit means back to said second heating element means; a source of voltage; and supply circuit means connected to said source of voltage, to the output of said integrating circuit means and to the supply terminals of said bridge for providing to said bridge a supply voltage which is inversely proportional to the output voltage of said integrating means, whereby the output voltage of said integrating circuit means has a magnitude representative of the RMS value of the input signal.
Claim 3
Dependent Claim
13 words
A device according to claim 1 in which said temperature sensors are resistors.
Claim 4
Dependent Claim
63 words
A device according to claim 2 in which each of the four arms of said bridge comprises such a temperature sensitive resistor, all substantially identical, with said first heating element means being in thermal contact with the resistors of two electrically-opposed arms of the bridge and the second heating element being in thermal contact with the resistors of the other two electrically-opposed arms.
Claim 5
Dependent Claim
154 words
A device according to claim 2, in which the integrating means comprises a voltage-to-frequency converter connected to receive the voltage representative of the unbalance of the bridge and adapted to produce pulses representative of the polarity (positive or negative) of the bridge unbalance voltage, the frequency of said pulses being proportional to said unbalance voltage; dividing means connected to the output of said voltage-to-frequency converter for dividing the frequency of the pulses by an amount which increases linearly with time; and pulse counter means connected to the output of said dividing means for counting algebraically the time divided pulses associated with positive and/or negative bridge unbalance voltage, whereby the count in the pulse counter means varies as the time integral of the bridge unbalance voltage divided by time; and a digital-to-analogue converter connected to the output of the pulse counter means for converting the digital representation of the pulse counter means into analogue form.
Claim 6
Dependent Claim
37 words
A device according to claim 4 in which said dividing means comprises two division circuits, one for the pulses associated with positive bridge unbalance voltage and the other for the pulses associated with negative bridge unbalance voltage.
Claim 7
Dependent Claim
110 words
A device according to claim 5 wherein each said division circuit comprises: a first pulse counter connected to the corresponding output of the voltage-to-frequency converter; a Clock pulse generator; a second pulse counter identical to said first pulse counter and connected to the output of said clock pulse generator; and comparison circuit means connected between said first and second pulse counters for producing an output pulse when said counters contain the same count, said output pulse being used to reset said first pulse counter and to increment the previously mentioned pulse counter means up when the bridge unbalance is of positive polarity and down when the bridge unbalance is negative.
Claim 8
Dependent Claim
98 words
A device according to claim 2, in which said supply means comprise a multiplier circuit one input of which is connected to the output of the digital-to-analogue converter and a differential amplifier the inverting input of which is connected to the output of the multiplier circuit, the non-inverting input to a voltage source and the output to the other input of the multiplier circuit, whereby the output voltage of this amplifier, which is the supply voltage of the bridge, represents the ratio of the output voltage of the said source to the output voltage of the digital-to-analogue converter.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-10-28 | 1978-04-29 | 1978-10-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-28 | 1982-04-29 | 1982-10-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-28 | 1986-04-29 | 1986-10-29 | $7700.00 | Window Closed / Lapsed |