CN204274423U - Clinical thermometer auto-calibration circuits - Google Patents
Clinical thermometer auto-calibration circuits Download PDFInfo
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- CN204274423U CN204274423U CN201420772318.7U CN201420772318U CN204274423U CN 204274423 U CN204274423 U CN 204274423U CN 201420772318 U CN201420772318 U CN 201420772318U CN 204274423 U CN204274423 U CN 204274423U
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Abstract
The utility model discloses clinical thermometer auto-calibration circuits, comprise constant current generating circuit and signal switching circuit, constant current generating circuit provides constant current signal for signal switching circuit, signal switching circuit comprises current switching analog switch and voltage switching analog switch, the precision standard resistance of ground connection is connected with after first gear port NC of current switching analog switch and the first gear port NC parallel connection of voltage switching analog switch, the critesistor of ground connection is connected with after the second gear bit port NO of current switching analog switch and the second gear bit port NO parallel connection of voltage switching analog switch, switch-over control signal is connected with after the control signal input port IN of current switching analog switch and the control signal input port IN parallel connection of voltage switching analog switch, the signal port COM of current switching analog switch is connected with the port I of constant current generating circuit, good stability, certainty of measurement does not affect by environmental change and component aging, exempt the worries that user demarcates.
Description
Technical field
This utility model relates to body temperature collection, specifically clinical thermometer auto-calibration circuits.
Background technology
Divide the main critesistor (NTC) of negative temperature coefficient that adopts as temperature probe to the collection of animal heat at present.Its resistance value reduces with the rising of temperature.Temperature survey is in fact then the measurement to probe resistance.
Measuring resistance generally adopts bridge method or constant flow method.No matter adopt which kind of method, all will use amplifying circuit, voltage or current reference circuit.These circuit performances all can change with the change of ambient temperature, time.Namely in so-called temperature drift, time, float.
Current animal heat meter, only when product export, by the method for demarcating, temporarily revises the individual variation of circuitry specifications, temperature drift.Within a period of time of dispatching from the factory, certainty of measurement can reach design objective.But with the change of ambient temperature, the increase of service time.Comprise the reason such as humidity, component aging.Temperature measurement accuracy can reduce greatly.Can only be calibrated by the method for again demarcating.But temperature correction needs the professional equipments such as thermostatic bath, general user does not possess such condition.
Utility model content
The purpose of this utility model is to provide a kind of clinical thermometer auto-calibration circuits, and this clinical thermometer auto-calibration circuits adopts built-in calibration circuit, all calibrates circuit system, obtain calibration factor by measurement standard resistance before each measurement.Thus the thermosensitive resistance of actual measurement is calibrated, to obtain temperature value accurately.This circuit ensure that the accuracy of measurement, also reduces the maintenance cost of equipment simultaneously.
The purpose of this utility model is achieved through the following technical solutions: clinical thermometer auto-calibration circuits, comprise constant current generating circuit and signal switching circuit, constant current generating circuit provides constant current signal for signal switching circuit, signal switching circuit comprises current switching analog switch and voltage switching analog switch, current switching analog switch and voltage switching analog switch all have control signal input port IN, signal port COM, first gear port NC, second gear bit port NO, the precision standard resistance of ground connection is connected with after first gear port NC of current switching analog switch and the first gear port NC parallel connection of voltage switching analog switch, the critesistor of ground connection is connected with after the second gear bit port NO of current switching analog switch and the second gear bit port NO parallel connection of voltage switching analog switch, switch-over control signal is connected with after the control signal input port IN of current switching analog switch and the control signal input port IN parallel connection of voltage switching analog switch, the port-for-port I of constant current generating circuit output constant current signal, the signal port COM of current switching analog switch is connected with the port I of constant current generating circuit, the signal port COM output voltage signal of voltage switching analog switch.
Signal switching circuit is as Center main points of the present invention, and it possesses 2 duties, is respectively align mode and measuring state:
During calibration: constant current signal is input to current switching analog switch, after current switching analog switch receives switch-over control signal, the signal port COM of current switching analog switch is communicated with the first gear port NC of current switching analog switch, therefore can reach and be loaded on precision standard resistance by switch-over control signal control constant current signal, the voltage signal that precision standard resistance produces, after voltage switching analog switch receives switch-over control signal, the signal port COM of voltage switching analog switch is communicated with the first gear port NC of pressure switching analoging switch, the voltage signal that precision standard resistance produces is by voltage switching analog switch, finally output to the signal port COM coating-forming voltage signal of voltage switching analog switch.
During measurement: constant current signal is input to current switching analog switch, after current switching analog switch receives switch-over control signal, the signal port COM of current switching analog switch is communicated with the second gear bit port NO of current switching analog switch, therefore can reach and be loaded on critesistor by switch-over control signal control constant current signal, the voltage signal that critesistor produces, after voltage switching analog switch receives switch-over control signal, the signal port COM of voltage switching analog switch is communicated with the second gear bit port NO of pressure switching analoging switch, the voltage signal of critesistor is by voltage switching analog switch, finally output to the signal port COM coating-forming voltage signal of voltage switching analog switch.
The voltage signal produced during calibration is called calibrate voltage signal, and the voltage signal produced during measurement is called measurement voltage signal.
Calibrate voltage signal carries out AD conversion through later stage circuit, then calculates ideally according to Ohm's law Rs*I=U, the voltage U that precision standard resistance should produce.Later stage circuit calculates system correction factor F according to the difference of the calibrate voltage signal that theoretical voltage U and actual measurement obtain.
Measurement voltage signal carries out AD conversion through later stage circuit, makes later stage circuit obtain the voltage U t that critesistor produces.Ut is revised by calibration factor F by later stage circuit, can obtain not by the real voltage Ut ' of circuit error effect.According to Ohm's law Rt=Ut '/I, obtain the value of Rt.The resistance v. temperature correspondence table provided according to critesistor manufacturer again can obtain the temperature of measurement.
In order to reduce the impact of feedback sample on the constant current signal exported, described constant current generating circuit comprises operational amplifier U5B and operational amplifier U5A, resistance R14 is in series with between the normal phase input end of operational amplifier U5B and the outfan of operational amplifier U5A, the normal phase input end of operational amplifier U5B is also connected with resistance R11 simultaneously, resistance R11 is connected with voltage reference signal, the inverting input of operational amplifier U5B is connected with earth resistance R12, the inverting input of operational amplifier U5B is also connected with the resistance R13 of series connection, sample resistance, resistance R13 is connected with the outfan of operational amplifier U5B with the junction point of sample resistance, sample resistance is connected with port I, port I is also connected with the normal phase input end of operational amplifier U5A, the inverting input of operational amplifier U5A is connected with the outfan of operational amplifier U5A.Resistance in traditional constant current generating circuit can divide to walk portion of electrical current, causes output error, and the circuit of this structure adopts positive feedback loop 2 and negative feedback loop 3 simultaneously, can reduce this error.
In order to the calculating of later stage circuit is simplified, the electric current that port I is exported is I=Vref/R17, Vref is the magnitude of voltage of voltage reference signal, R17 is the resistance of sample resistance, in order to meet this condition, resistance of the present invention can adopt following situation: the resistance ratio of described resistance R13 and resistance R12 is 1:1, and the resistance of resistance R13 and resistance R12 is all 100 ohm, the resistance ratio of described resistance R11 and resistance R14 is 1:1, and the resistance of resistance R11 and resistance R14 is all 100 ohm.
Describedly also comprise amplifying circuit, voltage signal is input to amplifying circuit, amplifying circuit comprises operational amplifier U5D, voltage signal is input to the normal phase input end of operational amplifier U5D, the inverting input calculating amplifier U5D is connected with earth resistance R22, the inverting input calculating amplifier U5D is also connected with resistance R24, and resistance R24 is connected with the outfan calculating amplifier U5D.
Above-mentioned amplifying circuit is a conventional amplifying circuit, can also adopt plural serial stage amplifying circuit or other forms of amplifying circuit in this circuit, and its effect is amplified calibrate voltage signal and measurement voltage signal, facilitates the process of later stage circuit.
The utility model has the advantage of: structure is simple, and cost is low, adopts the animal heat meter of this circuit production, can measure animal heat accurately.Long-time stability are good, and certainty of measurement does not affect by environmental change and component aging, exempt the worries that user demarcates.。
Accompanying drawing explanation
Fig. 1 is system structure schematic diagram of the present utility model.
Fig. 2 is constant current generating circuit schematic diagram of the present utility model.
Fig. 3 is signal switching circuit schematic diagram of the present utility model.
Fig. 4 is amplifying circuit schematic diagram of the present utility model.
Detailed description of the invention
Below in conjunction with embodiment and accompanying drawing, the utility model is described in further detail, but embodiment of the present utility model is not limited thereto.
Embodiment 1:
As Figure 1-Figure 2.
Clinical thermometer auto-calibration circuits, comprise constant current generating circuit and signal switching circuit, constant current generating circuit provides constant current signal 13 for signal switching circuit, signal switching circuit comprises current switching analog switch 8 and voltage switching analog switch 11, current switching analog switch 8 and voltage switching analog switch 11 all have control signal input port IN, signal port COM, first gear port NC, second gear bit port NO, the precision standard resistance 9 of ground connection is connected with after first gear port NC of current switching analog switch 8 and the first gear port NC parallel connection of voltage switching analog switch 11, the critesistor 10 of ground connection is connected with after the second gear bit port NO of current switching analog switch 8 and the second gear bit port NO parallel connection of voltage switching analog switch 11, switch-over control signal 7 is connected with after the control signal input port IN of current switching analog switch 8 and the control signal input port IN parallel connection of voltage switching analog switch 11, the port-for-port I of constant current generating circuit output constant current signal 13, the signal port COM of current switching analog switch 8 is connected with the port I of constant current generating circuit, the signal port COM output voltage signal 12 of voltage switching analog switch 11.
Signal switching circuit is as Center main points of the present invention, and it possesses 2 duties, is respectively align mode and measuring state:
During calibration: constant current signal 13 is input to current switching analog switch 8, after current switching analog switch 8 receives switch-over control signal 7, the signal port COM of current switching analog switch 8 is communicated with the first gear port NC of current switching analog switch 8, therefore can reach and control constant current signal by switch-over control signal 7 and be loaded on precision standard resistance 9, the voltage signal that precision standard resistance 9 produces, after voltage switching analog switch 11 receives switch-over control signal 7, the signal port COM of voltage switching analog switch 11 is communicated with the first gear port NC of pressure switching analoging switch 11, the voltage signal that precision standard resistance 9 produces is by voltage switching analog switch 11, finally output to the signal port COM coating-forming voltage signal 12 of voltage switching analog switch 11.
During measurement: constant current signal 13 is input to current switching analog switch 8, after current switching analog switch 8 receives switch-over control signal 7, the signal port COM of current switching analog switch 8 is communicated with the second gear bit port NO of current switching analog switch 8, therefore can reach and control constant current signal by switch-over control signal 7 and be loaded on critesistor 10, the voltage signal that critesistor 10 produces, after voltage switching analog switch 11 receives switch-over control signal 7, the signal port COM of voltage switching analog switch 11 is communicated with the second gear bit port NO of pressure switching analoging switch 11, the voltage signal of critesistor 10 is by voltage switching analog switch 11, finally output to the signal port COM coating-forming voltage signal 12 of voltage switching analog switch 11.
The voltage signal 12 produced during calibration is called calibrate voltage signal, and the voltage signal 12 produced during measurement is called measurement voltage signal,
Calibrate voltage signal carries out AD conversion through later stage circuit, then calculates ideally according to Ohm's law Rs*I=U, the voltage U that precision standard resistance 9 should produce.Later stage circuit calculates system correction factor F according to the difference of the calibrate voltage signal that theoretical voltage U and actual measurement obtain.
Measurement voltage signal carries out AD conversion through later stage circuit, makes later stage circuit obtain the voltage U t that critesistor 10 produces.Ut is revised by calibration factor F by later stage circuit, can obtain not by the real voltage Ut ' of circuit error effect.According to Ohm's law Rt=Ut '/I, obtain the value of Rt.The resistance v. temperature correspondence table provided according to critesistor manufacturer again can obtain the temperature of measurement.
As shown in Figure 1, later stage circuit described in said structure is the microprocessor in Fig. 1, microprocessor can provide switch-over control signal 7, with the mode of operation of control voltage switching analoging switch 11 and current switching analog switch 8, certainly, switch-over control signal 7 also can adopt other devices to provide control signal, such as low and high level signal generating circuit, not must adopt microprocessor to control, microprocessor also receives calibrate voltage signal simultaneously, thus calculate correction factor F, also measurement voltage signal can be revised according to correction factor F, thus export a measurement voltage signal accurately, draw after the measurement voltage signal finally exported from microprocessor is through the process of correction factor F, in circuit structure, also the above-mentioned computing of other circuit realiration can be adopted, the final measurement voltage signal exported through revising.The calculating process of microprocessor employing simultaneously, such as calculate ideally according to Ohm's law Rs*I=U, the voltage U that precision standard resistance 9 should produce, such computational process is an existing conventional Calculation Method, same, the method obtaining correction factor F adopts theoretical voltage U and surveys the difference of the calibrate voltage signal obtained and draw, this is also the conventional design of comparison circuit.The correction measurement voltage signal in later stage is also a conventional treatment method, and therefore, in practice, we only need to adopt existing operation method to implant in microprocessor.Therefrom can find out, during key point of the present invention, how to design a precision standard resistance 9 and a critesistor 10, how in a circuit Simultaneously test precision standard resistance 9 and critesistor 10 parameter, finally for post-processed.Under only having the adjustment measured at the same time, the mensuration of this structure can be just one and reliably measure accurately.
In order to reduce the impact of feedback sample on the constant current signal exported, described constant current generating circuit comprises operational amplifier U5B and operational amplifier U5A, resistance R14 is in series with between the normal phase input end of operational amplifier U5B and the outfan of operational amplifier U5A, the normal phase input end of operational amplifier U5B is also connected with resistance R11 simultaneously, resistance R11 is connected with voltage reference signal 1, the inverting input of operational amplifier U5B is connected with earth resistance R12, the inverting input of operational amplifier U5B is also connected with the resistance R13 of series connection, sample resistance 4, resistance R13 is connected with the outfan of operational amplifier U5B with the junction point of sample resistance, sample resistance is connected with port I, port I is also connected with the normal phase input end of operational amplifier U5A, the inverting input of operational amplifier U5A is connected with the outfan of operational amplifier U5A.Resistance in traditional constant current generating circuit can divide to walk portion of electrical current, causes output error, and the circuit of this structure adopts positive feedback loop 2 and negative feedback loop 3 simultaneously, can reduce this error.
In order to the calculating of later stage circuit is simplified, the electric current that port I is exported is I=Vref/R17, Vref is the magnitude of voltage of voltage reference signal 1, R17 is the resistance of sample resistance, in order to meet this condition, resistance of the present invention can adopt following situation: the resistance ratio of described resistance R13 and resistance R12 is 1:1, and the resistance of resistance R13 and resistance R12 is all 100 ohm, the resistance ratio of described resistance R11 and resistance R14 is 1:1, and the resistance of resistance R11 and resistance R14 is all 100 ohm.
Describedly also comprise amplifying circuit, voltage signal 12 is input to amplifying circuit, amplifying circuit comprises operational amplifier U5D, voltage signal 12 is input to the normal phase input end of operational amplifier U5D, the inverting input calculating amplifier U5D is connected with earth resistance R22, the inverting input calculating amplifier U5D is also connected with resistance R24, and resistance R24 is connected with the outfan calculating amplifier U5D.
Above-mentioned amplifying circuit is a conventional amplifying circuit, can also adopt plural serial stage amplifying circuit or other forms of amplifying circuit in this circuit, and its effect is amplified calibrate voltage signal and measurement voltage signal, facilitates the process of later stage circuit.
As mentioned above, then well this utility model can be realized.
Claims (7)
1. clinical thermometer auto-calibration circuits, it is characterized in that: comprise constant current generating circuit and signal switching circuit, constant current generating circuit provides constant current signal (13) for signal switching circuit, signal switching circuit comprises current switching analog switch (8) and voltage switching analog switch (11), current switching analog switch (8) and voltage switching analog switch (11) all have control signal input port IN, signal port COM, first gear port NC, second gear bit port NO, the precision standard resistance (9) of ground connection is connected with after first gear port NC of current switching analog switch (8) and the first gear port NC parallel connection of voltage switching analog switch (11), the critesistor (10) of ground connection is connected with after the second gear bit port NO of current switching analog switch (8) and the second gear bit port NO parallel connection of voltage switching analog switch (11), switch-over control signal (7) is connected with after the control signal input port IN of current switching analog switch (8) and the control signal input port IN parallel connection of voltage switching analog switch (11), the port-for-port I of constant current generating circuit output constant current signal (13), the signal port COM of current switching analog switch (8) is connected with the port I of constant current generating circuit, the signal port COM output voltage signal (12) of voltage switching analog switch (11).
2. clinical thermometer auto-calibration circuits according to claim 1, it is characterized in that: described constant current generating circuit comprises operational amplifier U5B and operational amplifier U5A, resistance R14 is in series with between the normal phase input end of operational amplifier U5B and the outfan of operational amplifier U5A, the normal phase input end of operational amplifier U5B is also connected with resistance R11 simultaneously, resistance R11 is connected with voltage reference signal (1), the inverting input of operational amplifier U5B is connected with earth resistance R12, the inverting input of operational amplifier U5B is also connected with the resistance R13 of series connection, sample resistance (4), resistance R13 is connected with the outfan of operational amplifier U5B with the junction point of sample resistance, sample resistance is connected with port I, port I is also connected with the normal phase input end of operational amplifier U5A, the inverting input of operational amplifier U5A is connected with the outfan of operational amplifier U5A.
3. clinical thermometer auto-calibration circuits according to claim 2, is characterized in that: the resistance ratio of described resistance R13 and resistance R12 is 1:1.
4. clinical thermometer auto-calibration circuits according to claim 3, is characterized in that: the resistance of resistance R13 and resistance R12 is all 100 ohm.
5. clinical thermometer auto-calibration circuits according to claim 2, is characterized in that: the resistance ratio of described resistance R11 and resistance R14 is 1:1.
6. clinical thermometer auto-calibration circuits according to claim 5, is characterized in that: the resistance of resistance R11 and resistance R14 is all 100 ohm.
7. clinical thermometer auto-calibration circuits as claimed in any of claims 1 to 6, it is characterized in that: describedly also comprise amplifying circuit, voltage signal (12) is input to amplifying circuit, amplifying circuit comprises operational amplifier U5D, voltage signal (12) is input to the normal phase input end of operational amplifier U5D, the inverting input calculating amplifier U5D is connected with earth resistance R22, and the inverting input calculating amplifier U5D is also connected with resistance R24, and resistance R24 is connected with the outfan calculating amplifier U5D.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420772318.7U CN204274423U (en) | 2014-12-10 | 2014-12-10 | Clinical thermometer auto-calibration circuits |
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| CN201420772318.7U CN204274423U (en) | 2014-12-10 | 2014-12-10 | Clinical thermometer auto-calibration circuits |
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| CN204274423U true CN204274423U (en) | 2015-04-22 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104970776A (en) * | 2015-07-03 | 2015-10-14 | 深圳市掌康科技有限公司 | Body temperature detection method and high-precision dynamic calibration electronic thermometer device |
| CN109601009A (en) * | 2017-08-01 | 2019-04-09 | 泰合意株式会社 | The bearing calibration of temperature sensor |
| CN110488889A (en) * | 2019-07-11 | 2019-11-22 | 湖南明康中锦医疗科技发展有限公司 | A kind of Breathing Suppotion device temperature collection control method and system |
-
2014
- 2014-12-10 CN CN201420772318.7U patent/CN204274423U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104970776A (en) * | 2015-07-03 | 2015-10-14 | 深圳市掌康科技有限公司 | Body temperature detection method and high-precision dynamic calibration electronic thermometer device |
| CN109601009A (en) * | 2017-08-01 | 2019-04-09 | 泰合意株式会社 | The bearing calibration of temperature sensor |
| CN110488889A (en) * | 2019-07-11 | 2019-11-22 | 湖南明康中锦医疗科技发展有限公司 | A kind of Breathing Suppotion device temperature collection control method and system |
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| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20150422 Termination date: 20151210 |
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| EXPY | Termination of patent right or utility model |