Patent US3906338A successfully refreshed from Google Patents.
US3906338A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Two wire current transmitter responsive to a resistance sensor input signal
Assignee: Rosemount Inc
•
Filing: 1974-09-27
•
Granted: 1975-09-16
•
Expires: 1994-09-27
Abstract
Abstract Circuitry including a resistance sensor is excited by an external power source. A reference voltage is established, the voltage developed across the sensor resistance is compared at an amplifier input with a reference voltage signal and the voltage across a feedback resistor, and the total current drawn through the circuitry adjusts as a function of the sensor resistance to give a balanced amplifier input. Total current may be made a linear function of sensor resistance or a non-linear function by proper selection of certain resistors.
Inventors
- 👤 Earl A Grindheim
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:31
CPC Classifications
G; G01; G01L; G01L9/00; G01L9/02; G01L9/04; G01L1/00; G01L1/20; G01L1/22; G01L1/225; G08; G08C; G08C19/00; G08C19/02; Y; Y10; Y10S; Y10S323/00; Y10S323/909
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
179 words
An electrical network comprising six resistors and a source of constant voltage and having first and second signal output terminals, a current input terminal and a current output terminal and means providing a source of current to said current input terminals, wherein the six resistors designated R1 through R6 and source designated VC are connected to be equivalent to an arrangement having R1, R2, R3, R4, R5 connected in a closed series loop in the order cited having the first and second signal output terminals between R1 and R4 and between R2 and R3 respectively, the current input terminal between R1 and R2, and the current output terminal between R4 and R5, and the source VC serially connected with R6 from a junction between R1 and R2 to a junction between R3 and R5, and connecting means to deliver a variable current from said current source to a junction between VC and R6 so that the total current designated IT delivered to the network which results in zero voltage difference at the first and second signal output terminals is
Claim 2
Dependent Claim
179 words
An electrical network comprising six resistors and a source of constant voltage and having first and second signal output terminals, a current input terminal and a current output terminal and means providing a source of current to said current input terminals, wherein the six resistors designated R1 through R6 and source designated VC are connected to be equivalent to an arrangement having R1, R2, R3, R4, R5 connected in a closed series loop in the order cited having the first and second signal output terminals between R1 and R4 and between R2 and R3 respectively, the current input terminal between R1 and R2, and the current output terminal between R4 and R5, and the source VC serially connected with R6 from a junction between R1 and R2 to a junction between R3 and R5, and connecting means to deliver a variable current from said current source to a junction between VC and R6 so that the total current designated IT delivered to the network which results in zero voltage difference at the first and second signal output terminals is
Claim 3
Dependent Claim
111 words
In a current transmitter having a current control circuit, a resistance bridge network comprising first, second, third and fourth resistance means connected in a closed series loop to provide first and second excitation junctions and first and second output signal junctions, a voltage reference element and fifth resistance means connected in series between said first and second excitation junctions, said voltage reference element and said fifth resistance means providing a third junction therebetween, said current control circuit including means responsive to voltages at said signal junctions to control the current through the third junction to thereby change the voltage across said fifth resistance means and the voltage to said excitation junctions.
Claim 4
Dependent Claim
111 words
In a current transmitter having a current control circuit, a resistance bridge network comprising first, second, third and fourth resistance means connected in a closed series loop to provide first and second excitation junctions and first and second output signal junctions, a voltage reference element and fifth resistance means connected in series between said first and second excitation junctions, said voltage reference element and said fifth resistance means providing a third junction therebetween, said current control circuit including means responsive to voltages at said signal junctions to control the current through the third junction to thereby change the voltage across said fifth resistance means and the voltage to said excitation junctions.
Claim 5
Dependent Claim
68 words
The resistance bridge network of claim 2 in which said first excitation junction is located between said first and second resistance means and said second excitation junction is located between said third and fourth resistance means, and in which said first output signal junction is located between said first and third resistance means and said second output signal junction is located between said second and fourth resistance means.
Claim 6
Dependent Claim
41 words
The resistance bridge network of claim 3 in which said first excitation junction constitutes a first current terminal, and in which said third resistance means includes first and second resistors joined together, the junction of which constitutes a second current terminal.
Claim 7
Dependent Claim
45 words
The resistance bridge network of claim 3 in which said first and second excitation junctions constitute first and second current terminals, and a resistor connected between said second output signal junction and said third junction between said voltage reference element and said fifth resistance means.
Claim 8
Dependent Claim
168 words
In a current transmitter, a resistance bridge network comprising first and second current terminalS, first and second signal terminals, a first resistor having one end connected to said first current terminal and its other end to said first signal terminal second resistor having one end connected to said first current terminal and its other end to said second signal terminal, a third resistor having one end connected to said first signal terminal and its other end to said second current terminal, a fourth resistor connected at one end to said second signal terminal, a fifth resistor connected at one end to said second current terminal, the other ends of said fourth and fifth resistors being connected together, a voltage reference element, a sixth resistor connected at one end to one end of said voltage reference element, and the other ends of said voltage reference element and said sixth resistor respectively being connected to the other ends of said fourth and fifth resistors and to said first current terminal.
Claim 9
Dependent Claim
168 words
In a current transmitter, a resistance bridge network comprising first and second current terminalS, first and second signal terminals, a first resistor having one end connected to said first current terminal and its other end to said first signal terminal second resistor having one end connected to said first current terminal and its other end to said second signal terminal, a third resistor having one end connected to said first signal terminal and its other end to said second current terminal, a fourth resistor connected at one end to said second signal terminal, a fifth resistor connected at one end to said second current terminal, the other ends of said fourth and fifth resistors being connected together, a voltage reference element, a sixth resistor connected at one end to one end of said voltage reference element, and the other ends of said voltage reference element and said sixth resistor respectively being connected to the other ends of said fourth and fifth resistors and to said first current terminal.
Claim 10
Dependent Claim
19 words
The resistance bridge network of claim 6 in which said third resistor varies with respect to a varying measurand.
Claim 11
Dependent Claim
185 words
In a current transmitter, a resistance bridge network comprising first and second current terminals, first and second signal terminals, a first resistor having one end connected to said first current terminal and its other end to said first signal terminal, a second resistor having one end connected to said first current terminal and its other end to said second signal terminal, a third resistor having one end connected to said first signal terminal and its other end to said second current terminal, a fourth resistor connected at one end to said second signal terminal and its other end to said second current terminal, a fifth resistor connected at one end to said second signal terminal, a voltage reference element connected at one end to said first current terminal, a sixth resistor connected at one end to said second current terminal and its other end to the other ends of said fifth resistor and said voltage reference element at a junction, said current transmitter including a current supply circuit providing a current through said junction in response to voltages at the first and second signal terminals.
Claim 12
Dependent Claim
185 words
In a current transmitter, a resistance bridge network comprising first and second current terminals, first and second signal terminals, a first resistor having one end connected to said first current terminal and its other end to said first signal terminal, a second resistor having one end connected to said first current terminal and its other end to said second signal terminal, a third resistor having one end connected to said first signal terminal and its other end to said second current terminal, a fourth resistor connected at one end to said second signal terminal and its other end to said second current terminal, a fifth resistor connected at one end to said second signal terminal, a voltage reference element connected at one end to said first current terminal, a sixth resistor connected at one end to said second current terminal and its other end to the other ends of said fifth resistor and said voltage reference element at a junction, said current transmitter including a current supply circuit providing a current through said junction in response to voltages at the first and second signal terminals.
Claim 13
Dependent Claim
19 words
The resistance bridge network of claim 8 in which said third resistor varies with respect to a varying measurand.
References Cited (Backward Citations)
US3085193A
Cited
US3319155A
Cited
US3316765A
Cited
US3413853A
Cited
US3439258A
Cited
US3859594A
Cited
US3562729A
Cited
US3503261A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-15 | 1979-03-17 | 1979-09-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-15 | 1983-03-17 | 1983-09-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-15 | 1987-03-17 | 1987-09-16 | $7700.00 | Window Closed / Lapsed |