Patent US3805616A successfully refreshed from Google Patents.
US3805616A
Expired / Lapsed
US
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Temperature measuring apparatus
Assignee: Yokogawa Electric Corp
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Filing: 1971-03-25
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Granted: 1974-04-23
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Expires: 1991-03-25
Abstract
Abstract A temperature-measuring system of the type wherein the sensing element is an electrical resistor connected by three leads to a measuring circuit. Two of the leads connect the resistor as a feedback element around an operational amplifier supplied at its input with a constant current. The third lead connects to a constant current source to produce through the other two leads current flows which are equal but opposite in direction, so as to minimize measurement errors when the lead resistances change with environmental effects such as ambient temperature and the like.
Inventors
- 👤 T Sugiyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:28
CPC Classifications
G; G01; G01K; G01K7/00; G01K7/16; G01K7/18; G01K7/20; G01K7/21
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
191 words
In a temperature measuring system wherein the resistance of a sensing resistor is measured to produce an output signal corresponding to the sensed temperature; the improvement comprising the combination of: an amplifier; first and second leads respectively connecting the terminals of said sensing resistor to the input and output of said amplifier to form a negative feedback circuit through the sensing resistor and the leads around the amplifier; first current-producing means connected to the input of said amplifier to cause a corresponding flow of current through the one of said leads connected to said input; and second current-producing means producing a greater magnitude of current than the first current-producing means and connected to said negative feedback circuit intermediate said leads and with a direction of flow relative to said feedback circuit opposite to that of the first current-producing means to cause a current to flow through the other lead in a direction opposite to the current flowing through said one lead, whereby the voltages across said two leads tend to cancel and the effect of changes in resistance of said two leads on the amplifier output signal tends to be nullified.
Claim 2
Dependent Claim
191 words
In a temperature measuring system wherein the resistance of a sensing resistor is measured to produce an output signal corresponding to the sensed temperature; the improvement comprising the combination of: an amplifier; first and second leads respectively connecting the terminals of said sensing resistor to the input and output of said amplifier to form a negative feedback circuit through the sensing resistor and the leads around the amplifier; first current-producing means connected to the input of said amplifier to cause a corresponding flow of current through the one of said leads connected to said input; and second current-producing means producing a greater magnitude of current than the first current-producing means and connected to said negative feedback circuit intermediate said leads and with a direction of flow relative to said feedback circuit opposite to that of the first current-producing means to cause a current to flow through the other lead in a direction opposite to the current flowing through said one lead, whereby the voltages across said two leads tend to cancel and the effect of changes in resistance of said two leads on the amplifier output signal tends to be nullified.
Claim 3
Dependent Claim
68 words
A system as claimed in claim 1, wherein said sensing resistor is of the type having three leads of equal resistance; said first lead being connected between one end of said resistor and said amplifier input; said second lead being connected between the other end of said resistor and said amplifier output; and said third lead being connected between said one resistor end and said second current-producing means.
Claim 4
Dependent Claim
18 words
A system as claimed in claim 2, wherein said first and second current-producing means maintain corresponding output currents.
Claim 5
Dependent Claim
28 words
A system as claimed in claim 3, wherein said second current-producing means produces a current of twice the magnitude of the current produced by said first current-producing means.
Claim 6
Dependent Claim
15 words
A system as claimed in claim 4, wherein said current-producing means are constant current sources.
Claim 7
Dependent Claim
31 words
A system as claimed in claim 1, including second feedback means connected between the output and input of said amplifier to linearize the changes in output signal with changes in temperature.
Claim 8
Dependent Claim
15 words
A system as claimed in claim 6, wherein said second feedback means provides negative feedbaCk.
Claim 9
Dependent Claim
15 words
A system as claimed in claim 6, wherein said second feedback means provides positive feedback.
Claim 10
Dependent Claim
187 words
In a resistance measuring system wherein a resistor is measured to produce an output signal corresponding to the resistance of the resistor, the improvement comprising the combination of: an amplifier; first and second leads respectively connecting the terminals of said resistor to the input and output of said amplifier to form a negative feedback circuit through the resistor and the leads around the amplifier; first current-producing means connected to the input of said amplifier to cause a corresponding flow of current through the one of the leads connected to said input; and second current-producing means producing a greater magnitude of current than the first current-producing means and connected to said negative feedback circuit intermediate said leads and with a direction of flow relative to said feedback circuit opposite to that of the first current-producing means to cause a current to flow through the other lead in a direction opposite to the current flowing through said one lead, whereby the voltages across said two leads tend to cancel and the effect of changes in resistance of said two leads on the amplifier output signal tends to be nullified.
Claim 11
Dependent Claim
187 words
In a resistance measuring system wherein a resistor is measured to produce an output signal corresponding to the resistance of the resistor, the improvement comprising the combination of: an amplifier; first and second leads respectively connecting the terminals of said resistor to the input and output of said amplifier to form a negative feedback circuit through the resistor and the leads around the amplifier; first current-producing means connected to the input of said amplifier to cause a corresponding flow of current through the one of the leads connected to said input; and second current-producing means producing a greater magnitude of current than the first current-producing means and connected to said negative feedback circuit intermediate said leads and with a direction of flow relative to said feedback circuit opposite to that of the first current-producing means to cause a current to flow through the other lead in a direction opposite to the current flowing through said one lead, whereby the voltages across said two leads tend to cancel and the effect of changes in resistance of said two leads on the amplifier output signal tends to be nullified.
Claim 12
Dependent Claim
67 words
A system as claimed in claim 9 wherein the resistor is of the type having three leads of equal resistance; said first lead being connected between one end of said resistor and said amplifier input; said second lead being connected between the other end of said resistor and said amplifier output; and said third lead being connected between said one resistor end and said second current-producing means.
Claim 13
Dependent Claim
18 words
A system as claimed in claim 10, wherein said first and second current-producing means maintain corresponding output currents.
Claim 14
Dependent Claim
28 words
A system as claimed in claim 11, wherein said second current-producing means produces a current of twice the magnitude of the current produced by said first current-producing means.
Claim 15
Dependent Claim
15 words
A system as claimed in claim 12, wherein said current-producing means are constant current sources.
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) | 1977-04-22 | 1977-10-22 | 1978-04-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-22 | 1981-10-22 | 1982-04-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-22 | 1985-10-22 | 1986-04-23 | $7700.00 | Window Closed / Lapsed |