US3722283A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Linear reading thermometer
Assignee: KETTERING SCIENT RES Inc
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Filing: 1971-11-17
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Granted: 1973-03-27
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Expires: 1991-11-17
Abstract
Abstract A silicon diode is used in a bridge circuit designed to provide linear changes in current through a meter in the bridge in response to changes in temperature on the diode. Variations from linear response in individual diode resistance characteristics as a function of temperature are compensated by a resistor in series with the diode and a second resistor in parallel with the diode, with these resistors being selected so that the resistance versus temperature characteristic of the entire circuit is fixed, thereby providing linear response and allowing interchangeability of diode temperature measuring circuits with a single bridge. All legs of the bridge circuit include resistances of the same order of magnitude to provide maximum sensitivity of the bridge to temperature measurements. In one embodiment one leg of the bridge is provided with a plurality of resistors, one of which is connected at a time in the bridge circuit to maintain the bridge near a balance condition through the entire temperature range of the instrument. In another embodiment, fixed resistors are used in each leg with readout being provided by a digital volt meter.
Inventors
- 👤 R Treharne
- 👤 J Riley
- 👤 E Thomas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:41
CPC Classifications
G; G01; G01K; G01K7/00; G01K7/01
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
173 words
A linear reading electronic thermometer including a constant voltage source; a bridge circuit including four legs each having approximately equal resistances, said bridge circuit having diagonally opposed terminals connected to said voltage source; means for measuring and displaying the current in said bridge circuit, said means connected to the remaining diagonally opposed terminals of said bridge circuit; and a diode temperature measuring device connected as the resistance in one leg of said bridge, said device including a silicon diode, the resistance of which varies inversely as a function of temperature, a first resistor connected in parallel with said diode and a second resistor connected in series with said parallel connection, the resistance of said first and second resistors being adjusted to compensate for the individual characteristics of said diode so that the diode temperature measuring device has a temperature-resistance characteristic which compensates for the nonlinear characteristics of said bridge circuit thereby causing current through said measuring and displaying means to vary linearly with variations in the temperature to which said diode is exposed.
Claim 2
Dependent Claim
173 words
A linear reading electronic thermometer including a constant voltage source; a bridge circuit including four legs each having approximately equal resistances, said bridge circuit having diagonally opposed terminals connected to said voltage source; means for measuring and displaying the current in said bridge circuit, said means connected to the remaining diagonally opposed terminals of said bridge circuit; and a diode temperature measuring device connected as the resistance in one leg of said bridge, said device including a silicon diode, the resistance of which varies inversely as a function of temperature, a first resistor connected in parallel with said diode and a second resistor connected in series with said parallel connection, the resistance of said first and second resistors being adjusted to compensate for the individual characteristics of said diode so that the diode temperature measuring device has a temperature-resistance characteristic which compensates for the nonlinear characteristics of said bridge circuit thereby causing current through said measuring and displaying means to vary linearly with variations in the temperature to which said diode is exposed.
Claim 3
Dependent Claim
49 words
The electronic thermometer of claim 1 wherein said diode measuring device is removably connected in said bridge circuit and wherein said first and second resistors compensate for variations and nonlinearity in the individual resistance characteristics of said diode thus allowing interchangeability of diode measuring devices with said bridge circuit.
Claim 4
Dependent Claim
21 words
The electronic thermometer of claim 1 further including a calibrating resistor connected between said constant voltage source and said bridge circuit.
Claim 5
Dependent Claim
62 words
The electronic thermometer of claim 1 wherein one of the legs of said bridge circuit includes a plurality of resistors, one resistor being connected in said bridge cIrcuit at a time to balance said bridge circuit substantially thus to enable a linear change in current through said measuring and display means as temperatures are measured by said diode over a wide range.
Claim 6
Dependent Claim
38 words
The electronic thermometer of claim 4 wherein the resistance of each of said plurality of resistors equals the resistance of said diode temperature measuring device at the lowest temperature of said diode in a predetermined range of temperatures.
Claim 7
Dependent Claim
51 words
The electronic thermometer of claim 1 further including a plurality of resistors connected in series with said measuring and display means, said resistors being selected in accordance with the range of temperature being measured to compensate for minor changes in current through said measuring and display means for various temperature ranges.
Claim 8
Dependent Claim
30 words
The thermometer of claim 1 wherein said measuring and display means includes a meter connected across said remaining diagonally opposed terminals to measure the output current in said bridge circuit.
Claim 9
Dependent Claim
42 words
The thermometer of claim 1 wherein said measuring and displaying means includes a resistor connected across said remaining diagonally opposed terminals and a digital volt meter for displaying the voltage across said resistor as a function of the temperature of said diode.
Claim 10
Dependent Claim
21 words
The thermometer of claim 1 wherein said bridge circuit is in balance when said diode is sensing a temperature of 0*C.
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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) | 1976-03-26 | 1976-09-25 | 1977-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-26 | 1980-09-25 | 1981-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-26 | 1984-09-25 | 1985-03-27 | $7700.00 | Window Closed / Lapsed |