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US3882728A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Temperature sensing circuit
Assignee: RCA Corp
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Filing: 1973-08-06
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Granted: 1975-05-13
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Expires: 1993-08-06
Abstract
Abstract One portion of a constant current is applied to one semiconductor device and the remainder to a second semiconductor device. When the temperature difference between the devices changes, the division of current also changes. An operational amplifier responsive to this division of current may be employed to drive an indicator of the temperature difference and to reestablish the original temperature difference between the devices.
Inventors
- 👤 Harold Allen Wittlinger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:27
CPC Classifications
G; G01; G01R; G01R17/00; G01R17/02; G01K; G01K7/00; G01K7/01; G01R19/00; G01R19/10
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
255 words
A measuring circuit comprising, in combination: two semiconductor devices, each including an input electrode and an output electrode, connected at their input electrodes, said devices being physically separated and thermally isolated from one another, the first of said devices being located next to an object whose temperature it is desired to measure relative to that of the second device and the second device being at a second location, said two semiconductor devices comprising transistors, each having an emitter electrode, a base electrode and a collector electrode, said input electrodes comprising said emitter electrodes and said output electrodes comprising said base electrodes; means connected to said input electrodes for applying one portion of a constant current to the first of said devices and the remainder of said constant current to the second of said devices, the ratio of said currents being a given value when the two devices are at the same temperature; means connected to said output electrodes for producing an output signal having a parameter at a reference value when the two devices are both at a reference temperature and responsive to a change from said given value of the ratio of the currents passing through said devices which occurs when said first device is heated by said object to a higher temperature than said second device, for producing an output signal having a parameter proportional to the change in temperature of said first device; and indicator means responsive to said output signal for producing an indication proportional to the value of said parameter.
Claim 2
Dependent Claim
255 words
A measuring circuit comprising, in combination: two semiconductor devices, each including an input electrode and an output electrode, connected at their input electrodes, said devices being physically separated and thermally isolated from one another, the first of said devices being located next to an object whose temperature it is desired to measure relative to that of the second device and the second device being at a second location, said two semiconductor devices comprising transistors, each having an emitter electrode, a base electrode and a collector electrode, said input electrodes comprising said emitter electrodes and said output electrodes comprising said base electrodes; means connected to said input electrodes for applying one portion of a constant current to the first of said devices and the remainder of said constant current to the second of said devices, the ratio of said currents being a given value when the two devices are at the same temperature; means connected to said output electrodes for producing an output signal having a parameter at a reference value when the two devices are both at a reference temperature and responsive to a change from said given value of the ratio of the currents passing through said devices which occurs when said first device is heated by said object to a higher temperature than said second device, for producing an output signal having a parameter proportional to the change in temperature of said first device; and indicator means responsive to said output signal for producing an indication proportional to the value of said parameter.
Claim 3
Dependent Claim
66 words
A measuring circuit as set forth in claim 1 further including heating means thermally coupled to the second of said devices, and means responsive to said output signal and coupled to said heating means for heating the second of said semiconductor devices to a temperature at which the original temperature difference between them is reestablished, thereby reestablishing the original distribution of constant current between said devices.
Claim 4
Dependent Claim
58 words
A heat measuring circuit as set forTh in claim 2 wherein said means for producing an output signal comprises an operational amplifier for producing a direct current level which is of substantially zero amplitude when the two devices are both at said reference temperature and which is at other times proportional to the temperature of said first device.
Claim 5
Dependent Claim
19 words
A heat measuring circuit as set forth in claim 3 wherein said indicator means comprises an average reading meter.
Claim 6
Dependent Claim
82 words
A heat measuring circuit as set forth in claim 4 wherein said object whose temperature it is desired to measure comprises a first integrated circuit element and wherein said heating means for said second device comprises a second integrated circuit element originally formed on the same substrate as and by the same process as the first such element and having substantially identical parameters, said first and second elements being physically separated from one another and heat isolated from one another, during operation.
Claim 7
Dependent Claim
23 words
A measuring circuit as set forth in claim 1 wherein said collector electrodes are connected together and to a source of operating voltage.
Claim 8
Dependent Claim
26 words
A temperature indicating circuit as set forth in claim 1, wherein the collector electrode of each transistor is connected to the base electrode of that transistor.
Claim 9
Dependent Claim
56 words
A temperature indicating circuit as set forth in claim 7, further including two resistors at least one of which is adjustable, one resistor connecting the base and collector electrodes of one transistor to an operating voltage terminal and the other resistor connecting the base and collector electrodes of the other transistor to said operating voltage terminal.
Claim 10
Dependent Claim
227 words
A temperature indicating circuit comprising, in combination: two semiconductor devices, each including an input electrode and an output electrode, connected at their input electrodes, said devices being physically separated and thermally isolated from one another, the first of said devices being located next to an object whose temperature it is desired to measure relative to that of the second device and the second device being at a second location; means connected to said input electrodes for applying one portion of a constant current to the first of said devices and the remainder of said constant current to the second of said devices, the ratio of said currents being a given value when the two devices are at the same temperature; means connected to said output electrodes for producing an output signal having a parameter at a reference value when the two devices are both at a reference temperature and responsive to a change from said given value of the ratio of the currents passing through said devices which occurs when said first device is heated by said object to a higher temperature than said second device, for producing an output signal having a parameter proportional to the change in temperature of said first device; and means responsive to said first device reaching a temperature lower than said second device for preventing the production of said output signal.
Claim 11
Dependent Claim
227 words
A temperature indicating circuit comprising, in combination: two semiconductor devices, each including an input electrode and an output electrode, connected at their input electrodes, said devices being physically separated and thermally isolated from one another, the first of said devices being located next to an object whose temperature it is desired to measure relative to that of the second device and the second device being at a second location; means connected to said input electrodes for applying one portion of a constant current to the first of said devices and the remainder of said constant current to the second of said devices, the ratio of said currents being a given value when the two devices are at the same temperature; means connected to said output electrodes for producing an output signal having a parameter at a reference value when the two devices are both at a reference temperature and responsive to a change from said given value of the ratio of the currents passing through said devices which occurs when said first device is heated by said object to a higher temperature than said second device, for producing an output signal having a parameter proportional to the change in temperature of said first device; and means responsive to said first device reaching a temperature lower than said second device for preventing the production of said output signal.
Claim 12
Dependent Claim
93 words
A temperature indicating circuit as set forth in claim 9 wherein said means for producing an output signal comprises an operational amplifier which produces a flow of current in one direction when the first device is heated to a higher temperature than the second device and which produces a flow of current in the opposite direction when the first device is at a lower temperature than the second device, and further including a diode coupled to the output terminal of said operational amplifier and poled to conduct current only in said one direction.
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) | 1978-05-12 | 1978-11-11 | 1979-05-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-12 | 1982-11-11 | 1983-05-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-12 | 1986-11-11 | 1987-05-13 | $7700.00 | Window Closed / Lapsed |