Patent US4556330A successfully refreshed from Google Patents.
US4556330A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Resistance thermometer and linearization circuitry
Assignee: Endress and Hauser SE and Co KG
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Filing: 1983-08-09
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Granted: 1985-12-03
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Expires: 2003-08-09
Abstract
Abstract The resistance thermometer comprises a temperature dependent measuring resistor (10) and a measuring circuit (11) for measuring the voltage drop at the measuring resistor which is produced by a current (I) flowing across the measuring resistor (10). The measuring resistor (10) lies in the feedback circuit of an operational amplifier (A 1 ) whose inverting input is applied via a resistor (21) to a constant reference voltage (E). To linearize the characteristic of the measuring circuit a voltage (k.U T ) is applied to the non-inverting input of the operational amplifier (A 1 ), which voltage is in a predetermined ratio (k) to the output voltage (U T ) of the measuring circuit (11).
Inventors
- 👤 Paulus P. L. Regtien
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 21:45
CPC Classifications
G; G01; G01K; G01K7/00; G01K7/16; G01K7/18; G01K7/20; G01K7/21
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
156 words
A resistance thermometer comprising a first operational amplifier having an inverting input, a non-inverting input and an output; a temperature-dependent measuring resistor having two current supply terminals and two voltage pick-up terminals separate from said current supply terminals, said temperature-dependent measuring resistor connected by said current supply terminals in a feedback loop from said output of said first operational amplifier to said inverting input of said first operational amplifier; means for applying a constant reference voltage via a resistor to said inverting input of said first operational amplifier; a differential amplifier having two inputs and an output; means for connecting said two inputs of said differential amplifier with said two voltage pick-up terminals, respectively; a voltage divider, having a tap, connected to said output of said differential amplifier, said voltage divider having a predetermined voltage divider ratio; and means for connecting said tap of said voltage divider with said non-inverting input of said first operational amplifier.
Claim 2
Dependent Claim
156 words
A resistance thermometer comprising a first operational amplifier having an inverting input, a non-inverting input and an output; a temperature-dependent measuring resistor having two current supply terminals and two voltage pick-up terminals separate from said current supply terminals, said temperature-dependent measuring resistor connected by said current supply terminals in a feedback loop from said output of said first operational amplifier to said inverting input of said first operational amplifier; means for applying a constant reference voltage via a resistor to said inverting input of said first operational amplifier; a differential amplifier having two inputs and an output; means for connecting said two inputs of said differential amplifier with said two voltage pick-up terminals, respectively; a voltage divider, having a tap, connected to said output of said differential amplifier, said voltage divider having a predetermined voltage divider ratio; and means for connecting said tap of said voltage divider with said non-inverting input of said first operational amplifier.
Claim 3
Dependent Claim
146 words
The resistance thermometer as claimed in claim 1, wherein said differential amplifier comprises a second operational amplifier having an inverting input, a non-inverting input and an output, said non-inverting input of said second operational amplifier defining one of said two inputs of said differential amplifier; a third operational amplifier having an inverting input, a non-inverting input and an output, said non-inverting input of said third operational amplifier defining the other of said two inputs of said differential amplifier; an adjustable resistor interconnecting said inverting inputs of said second and third operational amplifiers; and a fourth operational amplifier having a non-inverting input, an inverting input and an output, said inverting input and said non-inverting input connected to said outputs of said second and third operational amplifiers, respectively, via resistors of the same resistance value; said voltage divider being connected to the output of said fourth operational amplifier.
Claim 4
Dependent Claim
32 words
The resistance thermometer as claimed in claim 2, wherein a voltage derived from said constant reference voltage is applied to the non-inverting input of said fourth operational amplifier for zero point compensation.
Claim 5
Dependent Claim
36 words
The resistance thermometer as claimed in claim 3, wherein said non-inverting input of said fourth operational amplifier is connected via a resistor with the tap of a potentiometer to which said constant reference voltage is connected.
Claim 6
Dependent Claim
28 words
The resistance thermometer as claimed in claim 3, wherein said non-inverting input of said fourth operational amplifier is connected via a resistor to said constant reference voltage source.
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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) | 1988-12-02 | 1989-06-03 | 1989-12-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-12-02 | 1993-06-03 | 1993-12-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-12-02 | 1997-06-03 | 1997-12-03 | $7700.00 | Window Closed / Lapsed |