US4798093A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for sensor compensation
Assignee: Motorola Solutions Inc
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Filing: 1986-06-06
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Granted: 1989-01-17
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Expires: 2006-06-06
Abstract
Abstract Disclosed is an apparatus for pressure sensor compensation. The invention is best suited for pressure sensors of the type which may be mounted about a flexible member such that the resistance of one or more strain gauge resistors mounted thereon changes as pressure is exerted upon the flexible member. The pressure sensing apparatus comprises a bridge resistor arrangement for sensing pressure, and bridge control circuitry, coupled to an input terminal of the bridge, for compensating temperature induced variances in the bridge by controlling the voltage at the input terminal. The bridge has at least a first strain gauge resistor mounted on the flexible member, and at least one output terminal having a voltage which changes as pressure is exerted upon the flexible member. The bridge control circuitry has an additional strain gauge resistor which is used to monitor the temperature of the first strain gauge resistor.
Inventors
- 👤 Robert Kenoun
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 13:11
CPC Classifications
G; G01; G01L; G01L1/00; G01L1/20; G01L1/22; G01L1/2268; G01L1/2281; G01L9/00; G01L9/02; G01L9/06; G01L9/065
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
197 words
A pressure sensing apparatus of the type which automatically compensates for temperature variance, and which may be mounted about a flexible member such that the resistance of one or more strain gauge resistors mounted thereon changes as pressure is exerted upon the flexible member, the pressure sensing apparatus comprising: pressure sensing means for sensing pressure, said pressure sensing means having: an input terminal for receiving an input voltage, at least one first strain gauge resistor mounted on the flexible member, at least one substantially fixed value resistor having a value based on, at least in part, the rate of change over temperature of said at least one strain guage resistor, and at least one output terminal at which a voltage is developed which changes as pressure is exerted upon the flexible member; bridge control means coupled to said input terminal; and an additional strain gauge resistor situated such that it experiences temperature variations which correspond to temperature variations experienced by said first strain gauge resistor, and coupled with said bridge control means such that the voltage at said input terminal is controlled by said bridge control means to compensate for temperature induced variances in said bridge means.
Claim 2
Dependent Claim
197 words
A pressure sensing apparatus of the type which automatically compensates for temperature variance, and which may be mounted about a flexible member such that the resistance of one or more strain gauge resistors mounted thereon changes as pressure is exerted upon the flexible member, the pressure sensing apparatus comprising: pressure sensing means for sensing pressure, said pressure sensing means having: an input terminal for receiving an input voltage, at least one first strain gauge resistor mounted on the flexible member, at least one substantially fixed value resistor having a value based on, at least in part, the rate of change over temperature of said at least one strain guage resistor, and at least one output terminal at which a voltage is developed which changes as pressure is exerted upon the flexible member; bridge control means coupled to said input terminal; and an additional strain gauge resistor situated such that it experiences temperature variations which correspond to temperature variations experienced by said first strain gauge resistor, and coupled with said bridge control means such that the voltage at said input terminal is controlled by said bridge control means to compensate for temperature induced variances in said bridge means.
Claim 3
Dependent Claim
53 words
The pressure sensing apparatus according to claim 1, and wherein said bridge means further includes a second strain gauge resistor mounted on the flexible member and wherein the resistance value of said additional strain gauge resistor is approximately equal to the sum of the resistances of said first and second strain gauge resistors.
Claim 4
Dependent Claim
30 words
The pressure sensing apparatus according to claim 2, wherein said bridge control means further includes amplifier circuitry employing said additional strain gauge resistor in a feedback path around said amplifier.
Claim 5
Dependent Claim
30 words
The pressure sensing apparatus according to claim 1, wherein said bridge control means further includes amplifier circuitry employing said additional strain gauge resistor in a feedback path around said amplifier.
Claim 6
Dependent Claim
28 words
The pressure sensing apparatus according to claim 1, further including amplification circuitry, coupled to said output terminal, which includes circuitry to offset the voltage at said output terminal.
Claim 7
Dependent Claim
109 words
A temperature compensating pressure sensing apparatus, comprising: a flexible member; pressure sensing circuitry having an input terminal for receiving an input voltage, and including at least one first strain gauge resistor mounted on said flexible member; an additional strain gauge resistor situated near said first strain gauge resistor such that it experiences temperature variations which correspond to temperature variations experienced by said first strain gauge resistor; control circuitry having an amplifier which employs said additional strain gauge resistor in a feedback path with said amplifier to control the input voltage at said input terminal so as to compensate for temperature induced resistance variations of said first strain gauge resistor.
Claim 8
Dependent Claim
109 words
A temperature compensating pressure sensing apparatus, comprising: a flexible member; pressure sensing circuitry having an input terminal for receiving an input voltage, and including at least one first strain gauge resistor mounted on said flexible member; an additional strain gauge resistor situated near said first strain gauge resistor such that it experiences temperature variations which correspond to temperature variations experienced by said first strain gauge resistor; control circuitry having an amplifier which employs said additional strain gauge resistor in a feedback path with said amplifier to control the input voltage at said input terminal so as to compensate for temperature induced resistance variations of said first strain gauge resistor.
Claim 9
Dependent Claim
25 words
The pressure sensing apparatus according to claim 6, wherein said pressure sensing circuitry further includes a second strain gauge resistor mounted on the flexible member.
Claim 10
Dependent Claim
35 words
The pressure sensing apparatus according to claim 7, wherein the resistance value of said additional strain gauge resistor is approximately equal to the sum of the resistances of said first and second strain gauge resistors.
Claim 11
Dependent Claim
29 words
The pressure sensing apparatus according to claim 6, further including amplification circuitry, coupled to said output terminal, which includes resistor circuitry to offset the voltage at said output terminal.
Claim 12
Dependent Claim
169 words
A pressure sensing apparatus of the type which automatically compensates for offset drift and span temperature variance, and which may be mounted about a flexible member such that the resistance of one or more strain gauge resistors mounted thereon changes as pressure is exerted upon the flexible member, the pressure sensing apparatus comprising: a pressure sensing bridge circuit for sensing pressure and having: an input terminal for receiving an input voltage, two strain gauge resistors mounted on the flexible member, two substantially fixed value resistors, and at least one output terminal at which a voltage is developed which changes as pressure is exerted upon the flexible member; an additional strain gauge resistor situated such that it experiences temperature variations which correspond to temperature variations experienced by at least one of said strain gauge resistors; and bridge control means having an amplifier which employs said additional strain gauge resistor to control the input voltage at the input terminal so as to compensate for temperature induced variances in the bridge circuit.
Claim 13
Dependent Claim
169 words
A pressure sensing apparatus of the type which automatically compensates for offset drift and span temperature variance, and which may be mounted about a flexible member such that the resistance of one or more strain gauge resistors mounted thereon changes as pressure is exerted upon the flexible member, the pressure sensing apparatus comprising: a pressure sensing bridge circuit for sensing pressure and having: an input terminal for receiving an input voltage, two strain gauge resistors mounted on the flexible member, two substantially fixed value resistors, and at least one output terminal at which a voltage is developed which changes as pressure is exerted upon the flexible member; an additional strain gauge resistor situated such that it experiences temperature variations which correspond to temperature variations experienced by at least one of said strain gauge resistors; and bridge control means having an amplifier which employs said additional strain gauge resistor to control the input voltage at the input terminal so as to compensate for temperature induced variances in the bridge circuit.
Claim 14
Dependent Claim
37 words
A pressure sensing apparatus, according to claim 10, wherein the values of the two substantially fixed value resistors are based on, at least in part, the rate of change over temperature of the two strain gauge resistors.
Claim 15
Dependent Claim
33 words
The pressure sensing apparatus, according to claim 10, wherein the values of the two substantially fixed value resistors are based on, at least in part, the value of said two strain gauge resistors.
Claim 16
Dependent Claim
41 words
The pressure sensing apparatus, according to claim 10, wherein the values of the two substantially fixed value resistors are based on, at least in part, the value of and the rate of change over temperature of the two strain gauge resistors.
Claim 17
Dependent Claim
199 words
A pressure sensing apparatus of the type which automatically compensates for temperature variance, and which may be mounted about a flexible member such that the resistance of one or more strain gauge resistors mounted thereon changes as pressure is exerted upon the flexible member, the pressure sensing apparatus comprising: bridge means for sensing pressure, said bridge means having: an input terminal for receiving an input voltage, at least one first strain gauge resistor mounted on the flexible member, at least one substantially fixed value resistor having a value based on, at least in part, the value of and the rate of change over temperature of said at least one first strain resistor, and at least one output terminal at which a voltage is developed which changes as pressure is exerted upon the flexible member; bridge control means coupled to said input terminal; and an additional strain gauge resistor situated such that it experiences temperature variations which correspond to temperature variations experienced by said first strain gauge resistor, and coupled with said bridge control means such that the voltage at said input terminal is controlled by said bridge control means to compensate for temperature induced variances in said bridge means.
Claim 18
Dependent Claim
199 words
A pressure sensing apparatus of the type which automatically compensates for temperature variance, and which may be mounted about a flexible member such that the resistance of one or more strain gauge resistors mounted thereon changes as pressure is exerted upon the flexible member, the pressure sensing apparatus comprising: bridge means for sensing pressure, said bridge means having: an input terminal for receiving an input voltage, at least one first strain gauge resistor mounted on the flexible member, at least one substantially fixed value resistor having a value based on, at least in part, the value of and the rate of change over temperature of said at least one first strain resistor, and at least one output terminal at which a voltage is developed which changes as pressure is exerted upon the flexible member; bridge control means coupled to said input terminal; and an additional strain gauge resistor situated such that it experiences temperature variations which correspond to temperature variations experienced by said first strain gauge resistor, and coupled with said bridge control means such that the voltage at said input terminal is controlled by said bridge control means to compensate for temperature induced variances in said bridge means.
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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) | 1992-01-17 | 1992-07-18 | 1993-01-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-01-17 | 1996-07-18 | 1997-01-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-01-17 | 2000-07-18 | 2001-01-17 | $7700.00 | Window Closed / Lapsed |