CN211373868U - High-precision temperature measuring device - Google Patents

Abstract

The utility model provides a high-precision temperature measuring device, which comprises a temperature probe (100), a bridge circuit (200) connected with the temperature probe (200), a signal processing device (300) connected with the bridge circuit (200) and a power circuit (400) connected with the bridge circuit (200) and the signal processing device (300); the signal processing device (300) is a chip (U1) integrating a programmable amplifier, a reference source and analog-to-digital conversion. The utility model provides a pair of high accuracy temperature measuring device has advantages such as small, the precision is high, production is simple, and need not the profit bath and mark, can improve the measurement accuracy of device greatly, is applicable to various high accuracy, wide range, the comparatively strict application of volume requirement.

Description

High-precision temperature measuring device

Technical Field

The utility model relates to a temperature detection technology field, concretely relates to exempt from high accuracy temperature measuring device that oil water bath was markd.

Background

In the traditional temperature measuring device, the temperature precision is poor due to the difference between the wire resistance and the element of the sensor such as the thermistor NTC and the platinum resistor, and the like, so that the calibration must be carried out in an oil bath pot or a water pot at a plurality of temperature points when the temperature measuring device leaves a factory. The traditional method has high calibration difficulty, the precision is improved to a limited extent after calibration, and errors are easy to occur due to too much interference of human factors.

The temperature sensing probe for analog temperature acquisition generally adopts a thermistor and a platinum resistor, and is widely used due to wide temperature range and high precision. The signal conditioning device matched with the temperature sensor generally adopts resistance voltage division, then carries out sampling output by an ADC (analog to digital converter), and finally carries out operation by a microprocessor to obtain temperature data.

The prior art has the following 2 big disadvantages: 1) the internal resistance of the wire, generally from dozens of haumehms to several ohms, can introduce errors into the temperature. 2) The ADC sampling reference and the ADC voltage division reference are unstable or are separately supplied with power, so that errors are brought to the temperature. 3) Because the selection of the divider resistor is not reasonable, the temperature is increased due to the current, and the temperature deviation is increased. Since any one influence will bring about a loss of temperature accuracy.

Disclosure of Invention

The utility model aims to solve, among the prior art temperature measuring device need mark and influence the technical problem of product precision, provide a high accuracy temperature measuring device, need not the profit bath and mark, can improve the measurement accuracy of device greatly.

The utility model provides a high-precision temperature measuring device, which comprises a temperature probe, a bridge circuit connected with the temperature probe, a signal processing device connected with the bridge circuit and a power circuit connected with the bridge circuit and the signal processing device; the signal processing device is a chip integrating a programmable amplifier, a reference source and analog-to-digital conversion; the chip comprises 10 pins, wherein a first pin and a third pin are grounded, a fourth pin, a fifth pin, a sixth pin and a seventh pin are connected with the bridge circuit, the sixth pin and an eighth pin are connected with the power circuit, a ninth pin is connected with the power circuit through a first resistor, a tenth pin is connected with the power circuit through a second resistor, and the second pin is an alarm pin.

A high accuracy temperature measuring device, as preferred mode, bridge circuit includes third resistance, fourth resistance and sixth resistance, third resistance one end links to each other with the sixth pin, the third resistance other end links to each other with fifth pin and temperature probe, fourth resistance one end links to each other with the sixth pin, the fourth resistance other end links to each other with fourth pin, seventh pin and sixth resistance, sixth resistance one end links to each other with fourth pin, seventh pin and fourth resistance, the sixth resistance other end links to each other with temperature probe.

A high accuracy temperature measuring device, as preferred mode, power supply circuit includes fifth resistance, first electric capacity and steady voltage integrated circuit, fifth resistance one end links to each other with eighth pin, first resistance and second resistance, the fifth resistance other end links to each other with sixth pin, steady voltage integrated circuit and first electric capacity, steady voltage integrated circuit links to each other with fifth resistance, sixth pin and first electric capacity, first electric capacity and steady voltage integrated circuit ground connection respectively.

A high accuracy temperature measuring device, as preferred mode, steady voltage integrated circuit is TL431 chip. The voltage stabilizing integrated circuit can also adopt other output stabilizing and low-level wave chips, modules or circuits.

A high accuracy temperature measuring device, as preferred mode, the chip is the N7J chip of 12 bit precisions. The signal processing device may use other chips, modules or circuits with programmable amplifiers, which become amplifiers, reference sources.

The utility model discloses in the use, the temperature of temperature probe's response presents with the mode that the resistance value changes, thereby the resistance changes and influences Ui1N voltage in the bridge circuit and changes, through other known parameters, can calculate temperature probe's resistance to convert out the temperature value through looking up the table. N7J may simultaneously collect the differential voltage Udiff between Ui1N and Ui1P, the voltage Utemp of VCC _ TEMP, and the voltage Up of Ui 1P.

The calculation formula of the sensor resistance Rt is as follows:

Rt＝(Udiff+Up)/(Utemp-(Udiff+Up))×R3

as can be seen from the formula on the market, the resistance value of Rt is only influenced by the resistance value of R3 and the sampling precision of N7J and Utemp.

The resistance value of R3 can be accurately calculated by replacing the temperature probe with the standard resistor Rref before leaving the factory. The accuracy value of R3 is determined by the accuracy of N7J. The calculation formula is as follows:

R3＝(Utemp-(Udiff+Up))/(Udiff+Up)×Rref

r3 is made of a low-temperature-drift material, and the resistance precision is not required.

The supply voltage of the bridge circuit must be stable, the ripple is small, and the TL431 meets the requirements of stability and small ripple. The temperature drift of TL431 does not affect the sampling precision, and the output precision is determined by N7J sampling.

Different resistances can be used for R4 and R6 according to different sampling probes and different temperature ranges, for example, PT1000 is taken as an example, PT1000 is 1000 omega at 0 ℃, and if the measurement range is-20 ℃ to 50 ℃, the resistance of about 1K is preferably selected.

The precision of the temperature measuring device is determined only by the N7J chip, the chip is universal, if the precision is required to be improved, only the chip or the module with higher precision needs to be replaced, so the temperature measuring device does not need to be calibrated by an oil-water bath, and the measuring precision of the device can be greatly improved;

the utility model has the advantages of small, the precision is high, production is simple, is applicable to various high accuracy, wide range, the comparatively strict application field of volume requirement (clinical thermometer, cold chain, laboratory, boiler etc.).

Drawings

FIG. 1 is a schematic diagram of a high-precision temperature measuring device;

FIG. 2 is a circuit diagram of a signal processing device of a high-precision temperature measuring device;

FIG. 3 is a bridge circuit diagram of a high-precision temperature measuring device;

FIG. 4 is a power supply circuit diagram of a high-precision temperature measuring device.

Reference numerals:

100. a temperature probe; 200. a bridge circuit; 300. a signal processing device; 400. a power supply circuit; 1. a first pin; 2. a second pin; 3. a third pin; 4. a fourth pin; 5. a fifth pin; 6. a sixth pin; 7. a seventh pin; 8. an eighth pin; 9. a ninth pin; 10. a tenth pin; r1, a first resistor; r2, a second resistor; r3, third resistor; r4, fourth resistor; r5, fifth resistor; c1, a first capacitance; u1, chip; u2, voltage stabilization integrated circuit.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments.

Example 1

As shown in fig. 1, the present invention provides a high-precision temperature measuring device, which includes a temperature probe 100, a bridge circuit 200 connected to the temperature probe 100, a signal processing device 300 connected to the bridge circuit 200, and a power circuit 400 connected to the bridge circuit 200 and the signal processing device 300;

as shown in fig. 2, the signal processing apparatus 300 is a 12-bit precision N7J chip integrating a programmable amplifier, a reference source, and analog-to-digital conversion; the chip U1 includes 10 pins, a first pin 1 and a third pin 3 are grounded, a fourth pin 4, a fifth pin 5, a sixth pin 6 and a seventh pin 7 are connected to the bridge circuit 200, the sixth pin 6 and an eighth pin 8 are connected to the power supply circuit 400, a ninth pin 9 is connected to the power supply circuit 400 through a first resistor R1, a tenth pin 10 is connected to the power supply circuit 400 through a second resistor R2, and a second pin 2 is an alarm pin.

As shown in fig. 3, the bridge circuit 200 includes a third resistor R3, a fourth resistor R4, and a sixth resistor R6, one end of the third resistor R3 is connected to the sixth pin 6, the other end of the third resistor R3 is connected to the fifth pin 5 and the temperature probe 100, one end of the fourth resistor R4 is connected to the sixth pin 6, the other end of the fourth resistor R4 is connected to the fourth pin 4, the seventh pin 7, and the sixth resistor R6, one end of the sixth resistor R6 is connected to the fourth pin 4, the seventh pin 7, and the fourth resistor R4, and the other end of the sixth resistor R6 is connected to the temperature probe 100.

As shown in fig. 4, the power circuit 400 includes a fifth resistor R5, a first capacitor C1, and a voltage regulator integrated circuit U2, the voltage regulator integrated circuit U2 is a TL431 chip, one end of the fifth resistor R5 is connected to the eighth pin 8, the first resistor R1, and the second resistor R2, the other end of the fifth resistor R5 is connected to the sixth pin 6, the voltage regulator integrated circuit U2, and the first capacitor C1, the voltage regulator integrated circuit U2 is connected to the fifth resistor R5, the sixth pin 6, and the first capacitor C1, and the first capacitor C1 and the voltage regulator integrated circuit U2 are grounded, respectively.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can substitute or change the technical solution and the inventive concept of the present invention within the technical scope of the present invention.

Claims (5)

1. The utility model provides a high accuracy temperature measuring device which characterized in that: the temperature probe comprises a temperature probe (100), a bridge circuit (200) connected with the temperature probe (100), a signal processing device (300) connected with the bridge circuit (200) and a power supply circuit (400) connected with the bridge circuit (200) and the signal processing device (300); the signal processing device (300) is a chip (U1) integrating a programmable amplifier, a reference source and analog-to-digital conversion; the chip (U1) comprises 10 pins, a first pin (1) and a third pin (3) are grounded, a fourth pin (4), a fifth pin (5), a sixth pin (6) and a seventh pin (7) are connected with the bridge circuit (200), the sixth pin (6) and an eighth pin (8) are connected with the power circuit (400), a ninth pin (9) is connected with the power circuit (400) through a first resistor (R1), a tenth pin (10) is connected with the power circuit (400) through a second resistor (R2), and a second pin (2) is an alarm pin.

2. The high-precision temperature measuring device according to claim 1, wherein: the bridge circuit (200) comprises a third resistor (R3), a fourth resistor (R4) and a sixth resistor (R6), one end of the third resistor (R3) is connected with the sixth pin (6), the other end of the third resistor (R3) is connected with the fifth pin (5) and the temperature probe (100), one end of the fourth resistor (R4) is connected with the sixth pin (6), the other end of the fourth resistor (R4) is connected with the fourth pin (4), the seventh pin (7) and the sixth resistor (R6), one end of the sixth resistor (R6) is connected with the fourth pin (4), the seventh pin (7) and the fourth resistor (R4), and the other end of the sixth resistor (R6) is connected with the temperature probe (100).

3. The high-precision temperature measuring device according to claim 1, wherein: the power supply circuit (400) comprises a fifth resistor (R5), a first capacitor (C1) and a voltage-stabilizing integrated circuit (U2), one end of the fifth resistor (R5) is connected with the eighth pin (8), the first resistor (R1) is connected with the second resistor (R2), the other end of the fifth resistor (R5) is connected with the sixth pin (6), the voltage-stabilizing integrated circuit (U2) is connected with the first capacitor (C1), the voltage-stabilizing integrated circuit (U2) is connected with the fifth resistor (R5), the sixth pin (6) and the first capacitor (C1), and the first capacitor (C1) and the voltage-stabilizing integrated circuit (U2) are respectively grounded.

4. A high precision temperature measuring device according to claim 3, wherein: the voltage-stabilizing integrated circuit (U2) is a TL431 chip.

5. A high precision temperature measuring device according to any one of claims 1 to 4, wherein: the chip (U1) is a 12-bit precision N7J chip.

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