WO2023272908A1 - High-precision temperature measurement method and system - Google Patents

Abstract

A high-precision temperature measurement method and system. The high-precision temperature measurement method comprises the following steps: S1, a calibration phase, involving: performing calibration testing on a chip of a temperature sensor, and collecting output values of the temperature sensor at different calibration temperatures so as to form sampling data, wherein the sampling data includes at least two calibration arrays, and each calibration array is composed of calibration temperatures measured by a standard temperature measurement instrument and the output values of the chip of the temperature sensor; and S2, an actual measurement phase, involving: acquiring an actual output value of the chip of the temperature sensor, fitting the sampling data to obtain a temperature-output value curve, and substituting the actual output value into the temperature-output value curve to perform calculation so as to obtain an actual temperature. By means of the measurement method and the measurement system, more accurate sampling data is obtained by means of high-precision temperature calibration and collection, and the temperature-output value curve obtained by means of fitting the sampling data is closer to a true temperature curve of the chip of the temperature sensor, thereby greatly increasing the precision of temperature measurement.

Description

High precision temperature measurement method and measurement system technical field

The invention relates to the technical field of temperature detection, in particular to a high-precision temperature measurement method and a measurement system.

Background technique

Temperature detection is widely used in industrial and agricultural production, scientific research, and life. Due to the nonlinearity of temperature-sensitive devices, temperature drift, amplifier stability in the measurement circuit, and A/D converter noise, the temperature sensor’s performance is further improved. Accuracy and resolution are more difficult.

Most applications such as daily air conditioners, microwave ovens, ovens, cold chain transportation monitoring, etc. do not require too high temperature accuracy, and the accuracy of ±1.0 degrees Celsius and ±0.5 degrees is already satisfied, but there are also many occasions that require high-precision temperature measurement , For example, human body temperature measurement requires an accuracy of ±0.1 degrees, and the doping process in the production of integrated circuit chips requires higher-precision temperature control.

Most of the existing temperature sensor chips have an accuracy lower than ±0.5 degrees, and there are few types of chips with an accuracy higher than ±0.1 degrees, and they are expensive. Low-precision temperature sensor chips can only be used in cold chain transportation monitoring and other occasions that do not require high precision, and cannot be used for temperature measurement of animals and human bodies. In medical equipment, the temperature sensor chip requires that the measured temperature error is not higher than ±0.1 degrees .

In addition, temperature calibration is an important part of the production of temperature sensors, which is related to the accuracy of temperature sensors. The traditional calibration method is to calibrate at a set temperature point, which must be performed in a thermostat with a highly stable temperature. However, the stability of the temperature environment Sexual control is very difficult to achieve. The temperature in the thermostat cannot be maintained at the set temperature point. The temperature control accuracy of ordinary thermostat is usually ±0.5 degrees. The calibration temperature itself in the sampling data has a large error, which eventually leads to the failure of the temperature sensor chip The measurement accuracy is low.

Therefore, how to improve the accuracy of the existing temperature measurement method is a technical problem to be solved urgently in the industry.

Contents of the invention

In order to solve the defects of the existing technology, the present invention proposes a high-precision temperature measurement method and measurement system. The measurement method obtains more accurate sampling data through high-precision temperature calibration collection, and the temperature-output value curve obtained by fitting is closer to the temperature The real temperature curve of the sensor chip greatly improves the accuracy of temperature measurement.

The technical scheme adopted in the present invention is to design a high-precision temperature measurement method, comprising the following steps:

Step S1, the calibration stage, perform a calibration test on the temperature sensor chip, collect the output values of the temperature sensor at different calibration temperatures to form sampling data, the sampling data includes at least two calibration arrays, and each calibration array is the calibration temperature measured by a standard temperature measuring instrument and the output value of the temperature sensor chip;

Step S2, the actual measurement stage, obtain the actual output value of the temperature sensor chip, fit the sampled data to obtain a temperature-output value curve, and substitute the actual output value into the temperature-output value curve to calculate the actual temperature.

Preferably, each calibration array is obtained by measuring the standard temperature measuring instrument and the temperature sensor chip in the same test environment, and the standard temperature measuring instrument and the temperature sensor chip measure at the same time.

Preferably, the collection process of the calibration array includes:

Put the standard temperature measuring instrument and temperature sensor chip into the current test environment;

Reading the detection temperature of the standard temperature measuring instrument at intervals within a set time;

Determine whether the read detection temperature tends to be consistent;

If so, read the detection temperature of the standard temperature measuring instrument as the calibration temperature, and read the output value of the temperature sensor chip at the same time.

Preferably, the set time is greater than the maximum value of the thermal time constant of the standard temperature measuring instrument and the temperature sensor, and when the temperature difference between the detected temperatures read several times within the set time meets the set value, it is determined that the The detection temperature tends to be the same.

Preferably, step S2 also includes:

After calculating the actual temperature, determine whether the temperature difference between the actual temperature and the standard temperature of the environment where the temperature sensor chip is located is within a set error range;

If so, then determine that the temperature sensor chip is qualified;

If not, return to step S1 or determine that the temperature sensor chip is unqualified.

Preferably, the sampling data includes: a maximum calibration array and a minimum calibration array, the calibration temperature of the maximum calibration array is close to the maximum limit value of the actual use measurement range of the temperature sensor chip, and the calibration temperature of the minimum calibration array is close to the actual use measurement range of the temperature sensor chip minimum limit value of .

Preferably, each temperature sensor chip is provided with a unique identification code, and the sampling data is stored in the temperature sensor chip. When the temperature-output value curve is obtained by fitting the upper computer outside the temperature sensor chip, the sampling data, the actual output value And the actual temperature is bound with the identification code of its corresponding temperature sensor chip during the transmission process.

The present invention also proposes a high-precision temperature measurement system for realizing the above-mentioned high-precision temperature measurement method, including: a temperature sensor chip, a calibration control system for connecting with the temperature sensor chip, a constant temperature box for providing different calibration temperatures, and a temperature sensor for detecting A test box for whether the sensor is qualified, and a standard temperature measuring instrument for detecting temperature.

The temperature sensor chip is placed in different calibration temperatures during the calibration stage. The calibration control system sends a calibration command to the temperature sensor chip when the temperature of the incubator is stable. The temperature sensor chip or the calibration control system reads the calibration array and saves it; The detection stage is placed in the detection box, and the calibration control system compares the calculated actual temperature with the standard temperature detected by the standard temperature measuring instrument, and judges whether the temperature sensor chip is qualified according to the comparison result.

Among them, the temperature sensor chip includes: a communication interface unit; a temperature sensor unit, which includes a temperature sensitive device whose output value changes with temperature; a memory unit, which is used to save sampling data and chip parameters; a logic control unit, which controls the chip logic, reads The calibration temperature and the output value of the temperature sensor unit transmitted by the communication interface unit are obtained, and the output values of the temperature sensor unit at different calibration temperatures are collected to form sampling data and stored in the memory unit.

Preferably, the communication interface unit adopts a wired communication interface, such as an IIC communication interface and a single bus interface. The communication interface unit may also use a wireless communication interface, such as a high frequency or ultra high frequency RFID wireless tag.

Preferably, the temperature sensor unit also includes: a voltage stabilizing module that provides a stable voltage to the temperature sensitive device, a constant current module connected between the voltage stabilizing module and the temperature sensitive device, an AD converter connected to the output of the temperature sensitive device, AD The converted value output by the converter is the output value of the temperature sensor unit. The AD converter used in this embodiment may be an 8-bit, 12-bit, 16-bit or other AD converter.

Preferably, the calibration control system is set in the temperature sensor chip. During calibration, the calibration management system only transmits the calibration temperature without reading and writing the output value of the temperature sensor. The chip automatically writes the output value of the sensor chip into its corresponding memory array. ; The process of fitting the temperature curve of the temperature sensor with its own CPU and calculating the actual temperature is realized inside the temperature sensor chip. The calibration control system can also be set in the host computer other than the temperature sensor chip. The process of fitting the temperature curve and calculating the actual temperature is realized in the host computer. When the calibration control system is set in the host computer, in addition to the sampling data , the upper computer will also read the identification code, chip model, temperature range and accuracy stored in the memory unit.

Compared with the prior art, the present invention calibrates the output value of the temperature sensor chip at different temperatures, and fits the sampling data to obtain a temperature-output value curve. The calibration temperature is the temperature measured by the standard temperature measuring instrument and not the set ambient temperature. , so there is no need for a highly stable calibration temperature environment, and the ambient temperature can change slowly, which reduces the difficulty of calibration and makes it easy to achieve high-precision temperature calibration.

Further, the calibration process of the present invention is to obtain the output value that changes with the temperature when all parts of the whole chip are involved, fully consider the temperature drift of the temperature sensor chip itself, the discrete difference of parameters, and carry out the non-linear influence of the sensor. Error correction greatly improves the accuracy of temperature measurement.

Description of drawings

The present invention is described in detail below in conjunction with embodiment and accompanying drawing, wherein:

Fig. 1 is the fitting curve schematic diagram of an embodiment in the present invention;

Fig. 2 is the functional schematic diagram of temperature sensor chip among the present invention;

Fig. 3 is the control schematic diagram of temperature sensor chip among the present invention;

Fig. 4 is a schematic diagram of the calibration of the high-precision temperature measurement system in the present invention.

detailed description

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

The high-precision temperature measurement method proposed by the invention is suitable for improving the detection accuracy of the temperature sensor chip, and aims to solve the problem of the measurement accuracy of the temperature sensor chip at a lower cost. Specifically, the measurement method includes a calibration stage and an actual measurement stage. The sampling data is collected through the calibration stage, and the actual temperature is calculated according to the actual output value and the sampling data in the actual measurement stage.

Step S1, calibration phase, perform a calibration test on the temperature sensor chip, collect the output values of the temperature sensor at different calibration temperatures to form sampling data, the sampling data includes at least two calibration arrays, each calibration array is composed of calibration temperature and output value, calibration The temperature is measured by a standard temperature measuring instrument, and the output value is output by a temperature sensor chip.

In order to ensure the measurement accuracy, the standard temperature measuring instrument and the temperature sensor chip are placed in the same test environment, usually placed in an incubator. The time constant is more than 10 times, the ambient temperature inside the incubator is uniform, and the detection temperature of the standard temperature measuring instrument is used as the calibration temperature. The calibration temperature should be selected within the actual measurement range of the temperature sensor chip. The smaller the measurement range, the more calibrated temperature points, and the higher the measurement accuracy.

The acquisition process of each calibration array includes: putting the standard temperature measuring instrument and the temperature sensor chip into the current test environment, reading the detection temperature of the standard temperature measuring instrument at intervals within a set time, and judging the read detection temperature Whether it tends to be consistent; if so, read the detection temperature of the standard temperature measuring instrument as the calibration temperature, and read the output value of the temperature sensor chip at the same time.

It should be noted that the set time is greater than the maximum value of the thermal time constant of the standard temperature measuring instrument and the temperature sensor. When the temperature difference between the detected temperatures read several times within the set time meets the set value, it is determined that the detection The temperature tends to be the same. The ambient temperature remains unchanged for a certain period of time. The measurement equipment is the accurate temperature. The temperature measurement is lagging. The hysteresis coefficient of different temperature sensor materials is different, usually a few seconds, and the PN junction is 0.2--2 seconds. Some will be a bit longer, and for accurate temperature measurements, the set time must be greater than 3 times the hysteresis factor. A number of times usually refers to more than two times, and the specific number of times can be designed according to actual needs. The higher the measurement accuracy of the selected standard temperature measuring instrument is, the higher the calibration accuracy will be. The calibration accuracy of the temperature sensor is completely determined by the standard temperature measuring instrument and has nothing to do with the stable accuracy of the ambient temperature. After each collection of a calibration array is completed, the The standard temperature measuring instrument and the temperature sensor chip are put into the next test environment to collect the next calibration data.

The present invention does not limit the specific selection rules of the calibration temperature, but since the temperature-output value curve is nonlinear, from the perspective of the calibration effect, the selection of the calibration temperature needs to consider the actual application of the temperature sensor, and determine the measurement range according to the actual application. Accuracy requirements, and then select the appropriate calibration temperature point and the accuracy of the standard temperature measuring instrument, the higher the accuracy of the standard temperature measuring instrument, the higher the accuracy of the calibrated temperature sensor. The smaller the measurement range is, the smaller the calibration temperature range is, and the closer the fitted temperature curve is to the actual temperature curve of the sensor, the higher the measurement accuracy. In order to reduce the cost, the actual temperature range is T ₀ -T ₁ degree, only need to consider the temperature of this section, and try to improve the measurement accuracy of this section.

Generally speaking, the sampling data should include the largest calibration array, the smallest calibration array, and the intermediate calibration array. The calibration temperature of the largest calibration array is close to the maximum limit of the actual measurement range of the temperature sensor chip, and the calibration temperature of the smallest calibration array is close to the temperature sensor chip. The minimum limit value of the actual use of the measurement range, the calibration temperature of the intermediate calibration array is close to the common measurement value of the temperature sensor chip. For example, the temperature sensor dedicated to the human body, the actual measurement range of the temperature sensor chip is 34 degrees to 44 degrees, and the temperature beyond the range does not need to be considered. In fact, the accuracy of the measured value near it is also very high. In the calibration stage, you can choose 35 degrees, 37 degrees, 42 degrees, and 3 points for calibration. 37 degrees is close to the common measurement value of the human body temperature sensor. In the actual calibration process, the calibration temperature of the standard temperature measuring instrument may be 35.16 degrees, 36.82 degrees, 42.25 degrees, the interval of calibration temperature can be uneven.

Step S2, qualification detection stage, put the temperature sensor chip into the calibration environment, obtain the actual output value of the temperature sensor chip, fit the sampled data to obtain a temperature-output value curve, and substitute the actual output value into the temperature-output value curve Calculate the actual temperature, obtain the standard temperature of the calibration environment, and judge whether the temperature difference between the actual temperature and the standard temperature is within the set error range, if yes, determine that the accuracy of the temperature sensor chip is qualified, if not, return to step S1 or It is determined that the accuracy of the temperature sensor chip is unqualified.

After the temperature sensor chip is qualified, in actual use, obtain the actual output value of the temperature sensor chip, fit the sampled data to obtain a temperature-output value curve, and substitute the actual output value into the temperature-output value curve to calculate the actual temperature of the measured object. temperature, to achieve high-precision temperature measurement.

Existing temperature sensor chips are usually integrated circuit chips. Taking PN junctions as temperature sensitive devices, RFID tags as communication interfaces, and the output value of the temperature sensor chip as an AD conversion value of voltage that changes with temperature as an example, the technical principle of the present invention is described. The forward voltage drop of the PN junction of a crystal diode or triode has a negative temperature coefficient, which changes with temperature. Using this characteristic, the diode PN junction can be directly used as a temperature sensitive device. This sensor has good linearity, small size, thermal time constant of 0.2-2 seconds, and high sensitivity. The temperature measurement range is -50～+150℃. Different PN junction characteristics will have discrete differences, so at the same temperature, the voltage output will be different.

The following is the temperature, voltage and current relationship equation of the PN junction:

in:

q=1.6×10 ^-19 C, which is the charge of electrons.

K＝1.38×10 ^-23 J·K ^-1 , which is the Boltzmann constant,

T - absolute temperature.

I _f - the forward current in the PN junction.

The ratio of specific heat capacity in heat in γ is a constant.

Among them, V _g (0), C is a constant related to junction area and doping.

V _L is linear, and V _NL is nonlinear. At room temperature, the nonlinearity is very small, but it affects the measurement accuracy of temperature. Here, we also need to consider its influence as much as possible. Under constant current, the dependence of the PN junction forward voltage drop V _F on T mainly depends on the linear term, and the nonlinear term cannot be ignored for high-precision temperature measurement.

In order to ensure the accuracy of temperature measurement, the PN junction uses a constant current source as the working current to make the curve as linear as possible. When the RFID tag is used as a communication interface, since its power source comes from the magnetic field of the card reader, the PN junction power supply requires first to stabilize the voltage, and then to stabilize the current, so that the constant current source will not be affected by voltage fluctuations. The PN junction outputs a voltage signal that changes with temperature through a constant current source, and then amplifies, filters, and converts AD to become a digital signal. The output of the temperature sensor chip is an AD conversion value that changes with temperature. Consider the resolution according to the actual situation. Here Taking 16-bit AD conversion, the resolution of -50 ~ 150 ° C can theoretically reach 0.003 degrees, and each temperature AD conversion value occupies 2 bytes.

According to the actual needs of the temperature sensor, the present invention uses a standard temperature measuring instrument with appropriate precision. The higher the accuracy of the temperature sensor is, the higher the accuracy of the standard temperature measuring instrument is. The accuracy of the standard temperature measuring instrument should be higher than the accuracy of the temperature sensor by one The general requirement is that the accuracy of the standard temperature measuring instrument is 4 times that of the temperature sensor.

For example, for the temperature sensor of the PN junction, the linearity of itself is well calibrated, the measurement range is 0-50 degrees, the AD conversion takes 16 bits, and 4 points are calibrated. When the accuracy of the standard temperature measuring instrument is ±0.01 degrees, the temperature sensor measurement accuracy Higher than ±0.05 degrees, the measurement accuracy of the temperature sensor is also related to the temperature measurement range, the smaller the measurement range, the more calibration points, the higher the measurement accuracy of the temperature sensor.

In order to reduce the cost of the chip as much as possible, in general, the output value of the temperature sensor chip is the AD conversion value of the amplified voltage on the PN junction that changes with temperature, and no additional temperature compensation design for the chip is required. When the present invention is calibrated, the fitted curve has temperature compensation characteristics. Since the temperature curve of the PN junction is not a real straight line, and different chips have discreteness, V _g (0) and C in the formula are different. Moreover, each component inside the semiconductor chip will be affected by temperature, and a slight change in the ambient temperature will affect the output value of the AD conversion. The output value of the calibration of the present invention is obtained under the situation that each part of the whole sensor chip all participates, and the selection of calibration temperature is close to the maximum temperature and the minimum temperature of the measurement range of the temperature sensor chip, that is, the calibration takes into account the temperature of itself in the measurement range of the sensor Temperature drift, parameter discrete differences, and nonlinear effects make the fitted temperature-output value curve close to the real temperature curve of the sensor, which greatly improves the accuracy of temperature measurement.

Each temperature sensor chip has a unique identification code, which can be the chip ID. By calibrating N temperature points with high precision, errors such as nonlinearity, sensor chip distribution parameters, and temperature drift are corrected. The corresponding AD conversion value is stored in the memory unit of the temperature sensor chip. When the temperature-output value curve is fitted by a host computer other than the temperature sensor chip, when the temperature sensor is used to measure the temperature, the identification code, sampling data and the actual output value of the temperature sensor chip are sent together, and the host computer reads After the sensor data is taken, the sampled data is subjected to curve fitting to obtain the temperature-output value curve, and then the actual output value is substituted into the fitted curve to obtain the actual temperature of the measured object, which is displayed or transmitted to the application management system to realize temperature control. Measurement.

As shown in Figure 1, for example, the fitting process of a temperature sensor dedicated to the human body is used as an example. The accuracy of a standard temperature measuring instrument is required to be no less than ±0.02 degrees. degrees, corresponding to the actual calibration array (not real data, just to illustrate the function), A (3695, 42.16), B (6941, 37.85), C (8765, 35.05) (the picture is a schematic diagram, and the real temperature curve is different) , and calculate and process by line segment.

When the host computer reads the data of the temperature sensor, the temperature sensor sends the identification code, 3 sets of data A (3695, 42.16), B (6941, 37.85), C (8765, 35.05) in the memory unit and the measured voltage AD conversion The value X is given to the host computer, and the host computer obtains these 3 sets of data, which can be fitted into a quadratic curve. For simple calculation, it is fitted into 2 straight line segments AB and BC.

According to the straight line 2-point formula, the following equation is obtained.

Straight line AB: T=f(X)=(X-6941)*(42.16-37.85)/(3695-6941)+37.85, the value range of X<=6941.

Straight line BC: T=f(X)=(X-8765)*(37.85-35.05)/(6941-8765)+35.05, the value range of X>6941.

Suppose the measured voltage value is x1, x1<6941, then the corresponding temperature:

T=(x1-6941)*(42.16-37.85)/(3695-6941)+37.85.

Suppose the measured voltage value is x2, x2>6941, then the corresponding temperature:

T=(x2-8765)*(37.85-35.05)/(6941-8765)+35.05.

Due to the high accuracy of the calibrated temperature array, this curve is a curve close to the real characteristics of each temperature sensor chip itself. Since the calibration point takes into account all the distribution parameters of the chip, the constant current source error of the PN junction, the temperature of the amplifier, AD conversion, etc. Influenced, the accuracy of the temperature value obtained from the curve is very high.

In this way, what the host computer gets is not the direct temperature value, but the AD conversion value of the voltage corresponding to the temperature measured by the chip, which is a number in the coordinate array of a point on the curve, and another number of the array is calculated through the curve equation. This can not only solve the error caused by the discrete parameters of different chips, but also solve the error caused by the nonlinearity of the PN junction. Considering the actual accuracy requirements, when calibrating N temperature points, the curve can be divided into N-1 line segments, or it can be fitted into multiple curves and so on.

As shown in Figures 2 to 4, the present invention also proposes a high-precision temperature measurement system for realizing the above-mentioned measurement method. The high-precision temperature measurement system includes: a calibration control system, a temperature sensor chip, a constant temperature box, a detection box, and a Standard temperature measuring instrument for calibration temperature and standard temperature.

The temperature sensor chip is placed in different calibration temperatures during the calibration stage. The calibration control system sends a calibration command to the temperature sensor chip when the temperature of the incubator is stable. The temperature sensor chip reads the calibration array and saves it. Of course, it can also be read by the calibration control system. The calibration array is saved. The temperature sensor chip has a communication interface unit, a temperature sensor unit, a memory unit, a logic control unit, and a chip power supply unit. The communication interface unit is used to connect external devices. The communication interface unit uses a wired communication interface, such as an IIC communication interface and a single bus interface. The communication interface unit may also use a wireless communication interface, such as a high frequency or ultra high frequency RFID wireless tag. The temperature sensor unit includes a temperature sensitive device whose output value changes with temperature. The temperature sensitive device can use a thermistor, etc. The memory unit is used to save the sampling data, chip parameters and the actual output value of the latest measured temperature sensor unit. The chip parameters include chip ID and flag, etc., the memory unit has a memory for storing N calibration arrays. After receiving the calibration command, the logic control unit reads the calibration temperature and the output value of the temperature sensor unit transmitted by the communication interface unit, collects the output values of the temperature sensor unit at different calibration temperatures to form sampling data and stores it in the memory unit.

The temperature sensor chip is placed in the detection box during the qualified detection stage, and the calibration control system compares the calculated actual temperature with the standard temperature, and judges whether the temperature sensor chip is qualified according to the comparison result. The calibration control system obtains the actual output value of the temperature sensor unit, fits the temperature curve according to the sampling data of the temperature sensor chip, and substitutes the actual output value into the corresponding temperature curve to calculate the actual temperature. The detection temperature of the standard temperature measuring instrument is used as the standard temperature of the detection box, and it is judged whether the temperature difference between the actual temperature and the standard temperature is within the set error range. Chip accuracy is unqualified.

In some embodiments, the calibration control system is set in the temperature sensor chip, and the fitting of the temperature curve, the calculation of the actual temperature, and the qualification judgment are all implemented inside the temperature sensor chip. In other embodiments, the calibration control system can also be set in the host computer other than the temperature sensor chip, and the fitting of the temperature curve, the calculation of the actual temperature, and the qualification judgment are all implemented in the host computer. When the calibration control system is set in When in the upper computer, in addition to the sampling data, the upper computer will also read the identification code, chip model, temperature range and accuracy stored in the memory unit.

In a preferred embodiment, the temperature sensor unit also includes: a voltage stabilizing module that provides a stable voltage to the temperature sensitive device, a constant current module connected between the voltage stabilizing module and the temperature sensitive device, an AD converter connected to the output terminal of the temperature sensitive device The conversion value output by the AD converter is the output value of the temperature sensor unit. The AD converter used in this embodiment can be an 8-bit, 12-bit, 16-bit or other digital-digit AD converter. When working, the temperature sensitive element of the temperature sensor is powered by a constant current source to obtain a voltage signal that changes with temperature. This signal is amplified to the AD converter and converted into a digital signal of voltage, that is, the AD conversion value of the temperature. One temperature corresponds to one AD conversion value of temperature.

Because the calibration temperature is detected by a standard temperature measuring instrument, the present invention does not need a highly stable incubator, and the temperature of the incubating box can change slowly, requiring that its temperature change be less than the thermal time constant 10 of the standard temperature measuring instrument and the calibrated sensor more than double. The temperature sensor chip calibration and qualified inspection can be realized in one thermostat box, or there can be several thermostat boxes and a test box. The test box is used to verify whether the temperature sensor chip meets the design accuracy requirements. The configuration of the test box is the same as that of the thermostat box. .

The calibration control system is connected to the incubator. It must be able to read the temperature value measured by the standard temperature measuring instrument in the incubator. It must have the interface of the temperature sensor chip, which can communicate with the temperature sensor chip, read, write and set the data in the chip. The wireless interface and the RFID tag interface also need the support of the corresponding card reader, which can read and write the chip (RFID tag). Other calibrations, such as wafer calibration, need to make a special circuit to connect the sensor chip interface to ensure a good connection between the sensor chip and the setting circuit to achieve temperature calibration. Multiple temperature sensor chips can be calibrated simultaneously in one thermostat to improve production efficiency.

It should be noted that multiple thermostats can be designed to provide different calibration temperatures, and one temperature-variable thermostat can be designed to provide different calibration temperatures. Further, a standard temperature measuring instrument can be designed to be connected to the temperature sensor chip, and the standard temperature measuring instrument can be put into an incubator or a detection box together with the temperature sensor chip to accurately detect the temperature of the environment where the temperature sensor chip is located. Of course, in actual production, in order to simplify the operation process, a separate standard temperature measuring instrument can also be set in each thermostat and detection box. The present invention does not limit the number of thermostats and standard temperature measuring instruments, it only needs to ensure that the standard temperature measuring instruments and the temperature sensor chip are in the same environment.

As shown in Figure 4, taking multiple incubators and a standard temperature measuring instrument as an example, the measurement process of the measurement system is as follows:

The first step, the standard temperature measuring instrument and the temperature sensor chip are connected to the interface as required to ensure normal communication, placed in the incubator 1, and the temperature of the incubator 1 is controlled at the first temperature point T1, and the accuracy of the temperature is required to meet the design Require. The calibration control system continuously reads the temperature value in the standard temperature measuring instrument. When the temperature reaches a stable value, the calibration control system sends a calibration command. After receiving the calibration command, the temperature sensor chip collects the temperature measured by the standard temperature measuring instrument at this time. The temperature value T1, the output value X1 of the calibrated temperature sensor chip, and the calibration array (T1, X1) are stored in the first memory group.

In the second step, place the connected standard temperature measuring instrument and the temperature sensor chip in the incubator 2, and control the temperature of the incubator at the required second temperature point T2. Repeat the first step, collect the temperature value T2 measured by the standard temperature measuring instrument at this time, the output value X2 of the calibrated temperature sensor chip, and save the calibration array (T2, X2) to the second group of memory.

The third step is to repeat the same until the Nth calibration point is completed, and save the calibration array (TN, XN) to the Nth memory.

Step 4: After all temperature calibrations are completed, place the connected standard temperature measuring instrument and temperature sensor chip in the detection box, and control the temperature of the detection box at T. When the temperature is stable, the calibration control system sends a temperature collection command, and the temperature sensor chip sends the identification code, sampling data and the actual output value of the current temperature sensor chip to the calibration control system, and the calibration control system fits the temperature sensor chip according to the sampling data. Get the temperature-output value curve, substitute the actual output value into its corresponding temperature-output value curve to calculate the actual temperature, after calculating the actual temperature, use the detection temperature of the standard temperature measuring instrument in the detection box as the standard temperature of the detection box, judge Whether the temperature difference between the actual temperature and the standard temperature is within the set error range, if so, determine that the temperature sensor chip is qualified, if not, recalibrate the temperature sensor chip or determine that the temperature sensor chip is unqualified.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within range.

Claims (10)

1. The high-precision temperature measurement method is characterized in that it comprises the following steps:

   Step S1, calibration phase, perform a calibration test on the temperature sensor chip, collect the output values of the temperature sensor at different calibration temperatures to form sampling data, the sampling data includes at least two calibration arrays, and each calibration array is determined by a standard temperature measuring instrument The measured calibration temperature and the output value of the temperature sensor chip are composed;

   Step S2, the actual measurement stage, obtaining the actual output value of the temperature sensor chip, fitting the sampled data to obtain a temperature-output value curve, and substituting the actual output value into the temperature-output value curve to calculate the actual temperature .
2. The high-precision temperature measurement method according to claim 1, wherein each calibration array is obtained by measuring a standard temperature measuring instrument and the temperature sensor chip in the same test environment.
3. The high-precision temperature measurement method according to claim 2, wherein the acquisition process of the calibration array comprises:

   Put the standard temperature measuring instrument and the temperature sensor chip into the current test environment;

   Reading the detection temperature of the standard temperature measuring instrument at intervals within a set time;

   Determine whether the read detection temperature tends to be consistent;

   If so, read the detection temperature of the standard temperature measuring instrument as the calibration temperature, and read the output value of the temperature sensor chip at the same time.
4. The high-precision temperature measurement method according to claim 3, wherein the set time is greater than the maximum value of the thermal time constant of the standard temperature measuring instrument and the temperature sensor, and when the set time is continuously read several times within the set time If the temperature difference between the detected detected temperatures satisfies the set value, it is determined that the detected temperatures tend to be consistent.
5. The high-precision temperature measurement method according to claim 1, wherein said step S2 further comprises:

   After calculating the actual temperature, determine whether the temperature difference between the actual temperature and the standard temperature of the environment where the temperature sensor chip is located is within a set error range;

   If so, then determine that the temperature sensor chip is qualified;

   If not, return to step S1 or determine that the temperature sensor chip is unqualified.
6. The high-precision temperature measurement method according to any one of claims 1 to 5, wherein the sampling data includes: a maximum calibration array and a minimum calibration array, and the calibration temperature of the maximum calibration array is close to the temperature sensor chip The maximum limit value of the actual use measurement range of the temperature sensor chip, the calibration temperature of the minimum calibration array is close to the minimum limit value of the actual use measurement range of the temperature sensor chip.
7. According to the high-precision temperature measuring method according to any one of claims 1 to 5, it is characterized in that each of the temperature sensor chips is provided with a unique identification code, and the sampling data is stored in the temperature sensor chip, when When the temperature-output value curve is fitted by a host computer other than the temperature sensor chip, the sampling data, actual output value and actual temperature are bound with the identification code of the corresponding temperature sensor chip during transmission.
8. The high-precision temperature measurement system for realizing the high-precision temperature measurement method described in any one of claims 1 to 7 is characterized in that it includes: a temperature sensor chip, a calibration control system used to connect with the temperature sensor chip, and used to provide Thermostats with different calibration temperatures, test boxes for testing whether the sensors are qualified, and standard temperature measuring instruments for testing temperatures;

   The temperature sensor chip is placed in different calibration temperatures during the calibration phase, and the calibration control system sends a calibration command to the temperature sensor chip when the temperature of the thermostat is stable, and the temperature sensor chip or the calibration control system Read the calibration array and save it;

   The temperature sensor chip is placed in the detection box during the qualified detection stage, and the calibration control system compares the calculated actual temperature with the standard temperature detected by the standard temperature measuring instrument, and judges the temperature according to the comparison result Whether the sensor chip is qualified.
9. The high-precision temperature measurement system according to claim 8, wherein the temperature sensor chip comprises:

   communication interface unit;

   A temperature sensor unit, which includes a temperature sensitive device whose output value varies with temperature;

   A memory unit, which is used to save sampling data and chip parameters;

   A logic control unit, which controls the logic of the chip, reads the calibration temperature transmitted by the communication interface unit and the output value of the temperature sensor unit, and collects the output values of the temperature sensor unit at different calibration temperatures to form the sampling data and store them together into the memory unit.
10. The high-precision temperature measurement system according to claim 8, wherein the calibration control system is set in the temperature sensor chip or a host computer other than the temperature sensor chip.

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