EP0086462A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Pressure sensor employing semiconductor strain gauge
Assignee: Hitachi Ltd
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Filing: 1983-02-10
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Granted: —
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Expires: 2003-02-10
Abstract
Abstract Four semiconductor strain gauges constitute a bridge circuit (100). This bridge circuit and a sensitivity temperature compensation circuit (120) are connected in series, and a constant voltage is applied to the series circuit. The sensitivity temperature compensation circuit (120) varies a voltage across the bridge circuit, depending upon temperatures. The constant voltage is divided to produce a predetermined voltage. The predetermined voltage is selected to be equal to the voltage of one output side node (b) of the bridge circuit at the time when the semiconductor strain gauges are unstrained and at a predetermined temperature. The point (e) of this voltage and the output side node (b) are connected through a resistor (R Z3 ) so as to perform zero-point temperature compensation.
Inventors
- 👤 Hideo Sato
- 👤 Motohisa Nishihara
- 👤 Kazuji Yamada
- 👤 Seikou Suzuki
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 07:35
CPC Classifications
G; G01; G01L; G01L9/00; G01L9/02; G01L9/06; G01L9/065
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
210 words
A pressure sensor comprising: a bridge circuit (100) which has two arms connected at both their ends, and which includes at least one semiconductor strain gauge (R G1 . R G2' R G3 , R G4 ) between two middle points (b, d) thereof and one end of the arm, a sensitivity temperature compensation circuit (120) which is connected in series with said bridge circuit (100), and which varies an applied voltage of said bridge circuit (100) in dependence on a temperature so as to compensate a sensitivity temperature characteristic of said bridge, means (110) for applying a constant voltage to a series circuit consisting of said bridge circuit (100) and said sensitivity temperature compensation circuit (120) , amplification means (140) for differentially amplifying voltages at said middle points (b, d) of said two arms of said bridge circuit (100), and a zero-point temperature compensation circuit (130) by which a point (e) of a voltage equal to a potential of the middle point (b) of one arm of said bridge circuit at the time when said semiconductor strain gauge is unstrained and is at a predetermined temperature is connected to said middle point (b) of said one arm of said bridge circuit (100) through a resistor (R Z3 ) '
Claim 2
Dependent Claim
210 words
A pressure sensor comprising: a bridge circuit (100) which has two arms connected at both their ends, and which includes at least one semiconductor strain gauge (R G1 . R G2' R G3 , R G4 ) between two middle points (b, d) thereof and one end of the arm, a sensitivity temperature compensation circuit (120) which is connected in series with said bridge circuit (100), and which varies an applied voltage of said bridge circuit (100) in dependence on a temperature so as to compensate a sensitivity temperature characteristic of said bridge, means (110) for applying a constant voltage to a series circuit consisting of said bridge circuit (100) and said sensitivity temperature compensation circuit (120) , amplification means (140) for differentially amplifying voltages at said middle points (b, d) of said two arms of said bridge circuit (100), and a zero-point temperature compensation circuit (130) by which a point (e) of a voltage equal to a potential of the middle point (b) of one arm of said bridge circuit at the time when said semiconductor strain gauge is unstrained and is at a predetermined temperature is connected to said middle point (b) of said one arm of said bridge circuit (100) through a resistor (R Z3 ) '
Claim 3
Dependent Claim
45 words
A pressure sensor according to claim 1, wherein said sensitivity temperature compensation circuit is constructed of a series circuit consisting of a thermistor (R TH ) and a resistor (R S1 ), and a resistor (R S2 ) connected in parallel with said series circuit.
Claim 4
Dependent Claim
25 words
A pressure sensor according to claim 2, wherein said thermistor (R TH ) and said resistors (R S1 R S2 ) are thick film elements.
Claim 5
Dependent Claim
44 words
A pressure sensor according to claim 1, wherein the voltage point (e) of said zero-point temperature compensation circuit (130) is a node of two resistors (R Z1 , R Z2 ) which constitute a series circuit connected to the constant voltage application means (110).
Claim 6
Dependent Claim
19 words
A pressure sensor according to claim 4, wherein said resistors (R Z1 R Z2 ) are thick film resistors.
Claim 7
Dependent Claim
50 words
A pressure sensor according to claim 1, wherein said bridge circuit (100) includes four semiconductor strain gauges (R G1 - RG4), two of which (R G1 . R G3 ) in diagonally facing relationship undergo compressive strains and the other two (RG2, R G4 ) of which undergo tensile strains.
Claim 8
Dependent Claim
69 words
A pressure sensor according to claim 6, wherein a resistor (R 5 ) is further connected in parallel with one semiconductor strain gauge in that arm of said bridge circuit to which said zero-point temperature compensation circuit (130) is opposite, and the middle point (d) of said arm to which this resistor (R S ) is connected is connected to a minus input (-) of said amplification means (140).
Claim 9
Dependent Claim
87 words
A pressure sensor according to claim 1, wherein that middle point of said one arm of said bridge circuit (100) to which said zero-point temperature compensation circuit is connected is that one of said two middle points (b, d) at which the potential in the unstrained state and at the predetermined temperature is higher, when said semiconductor strain gauge has a positive zero-point temperature characteristic, and it is the other middle point at which the potential is lower, when said semiconductor strain gauge has a negative characteristic.
References Cited (Backward Citations)
No citation records indexed.
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