A thermal wind speed and direction sensor based on thermistor and thermopile and a working method thereof

Abstract

The application discloses a thermal type wind speed and direction sensor based on thermistors and thermoelectric piles and a working method thereof. The sensor structure comprises a thermistor, a thermoelectric pile, a heating resistor, a silicon substrate and a measurement and control IC. The heating resistor is square and located at the center of the substrate. Four thermistors and a thermoelectric pile parallel to the side edges of the heating resistor are distributed on the four sides of the heating resistor. The four parallel thermistors are connected to form a Wheatstone full-bridge temperature measurement structure, and the two parallel thermoelectric piles are connected to form a thermoelectric pile temperature measurement structure. The measurement and control IC is distributed at the four corners of the substrate and connected to the temperature measurement structure formed by the heating resistor, the thermoelectric pile and the thermistor, and is used for driving the detection structure and processing the output signal thereof. The application adopts a CMOS process, and the thermistor and the thermoelectric pile structure are redundant to each other, so that the wind speed and direction detection precision can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of micro-electro-mechanical system (MEMS), and in particular to a thermal wind speed and direction sensor based on thermistor and thermoelectric pile and a working method thereof. BACKGROUND

[0002] With the development of industry and agriculture, the types of sensors performing wind speed and direction detection tasks are continuously expanding. MEMS wind speed and direction sensors have the advantages of small size, low power consumption and batch production, which are not possessed by traditional mechanical, ultrasonic and capacitive wind speed and direction sensors, and have received more extensive attention and research.

[0003] The thermal MEMS wind speed and direction sensor obtains wind speed and direction information by measuring the change of the thermal field caused by the flow field. Its temperature measurement structure is simple, and it can be manufactured by CMOS and MEMS technology, and can be monolithically integrated with a measurement and control IC to further reduce the size. However, the improvement of its measurement accuracy still depends on the innovation of the structure.

[0004] The continuous development of industry and agriculture not only drives the expansion of the demand for wind speed and direction detection, but also puts forward higher requirements for the sensors performing wind speed and direction detection in terms of size, power consumption, accuracy and batch production.

[0005] However, most of the existing thermal MEMS wind speed and direction sensors still use PCB board-level circuit to process signals, which is not conducive to further reducing the size and batch production. Moreover, they mostly use calorimetric mode to measure wind direction. In this mode, the sensing structure of the sensor chip is mostly a central heating element and a central symmetric layout of thermistor pairs or thermocouple pairs arranged in the four orthogonal directions around the central heating element. This layout has insufficient accuracy. The patent with application number 201711380409 discloses a wind speed sensor with an 8-sided thermoelectric pile structure to increase the accuracy of the sensor. However, its sensing structure is relatively complex and occupies a large area, which cannot provide sufficient space for monolithic integration of the measurement and control IC. SUMMARY

[0006] The present application aims to meet the needs of miniaturization and improved accuracy, and provides a thermal wind speed and direction sensor based on thermistor and thermoelectric pile and a working method thereof. The measurement principle is simple and easy to implement, and the reliability is high.

[0007] To solve the above technical problems, the specific technical method of the present application is as follows:

[0008] The thermal wind speed and direction sensor based on thermistor and thermocouple comprises a silicon substrate, integrated heating resistor, thermocouple, thermistor and measurement and control IC on the silicon substrate; the heating resistor is square and located at the center of the silicon substrate, two thermistors and a thermocouple are parallelly arranged outside the four sides of the heating resistor, and the thermocouple is located outside the thermistor; the thermocouples on the two sides of the upper and lower parallel sides of the heating resistor are connected in series to form a thermocouple temperature measurement structure, the thermocouples on the two sides of the left and right parallel sides of the heating resistor are connected in series to form a thermocouple temperature measurement structure, and the two thermocouple temperature measurement structures are orthogonal to each other; the four thermistors on the upper and lower sides form a Wheatstone full-bridge temperature measurement structure, the four thermistors on the left and right sides form a Wheatstone full-bridge temperature measurement structure, and the two Wheatstone full-bridge temperature measurement structures are orthogonal to each other; the measurement and control IC is located at the four corners of the substrate and is centrally symmetrically distributed; the temperature measurement structure composed of the heating resistor, the thermocouple and the thermistor is monolithically integrated with the measurement and control IC, is realized by CMOS technology, and is connected by metal layer lead interconnection.

[0009] Further, the arrangement direction of the thermocouple is parallel to the side of the silicon substrate, and the hot end and the cold end are located on the two sides of the arrangement direction of the thermocouple; the thermocouple is close to the edge of the substrate.

[0010] Further, the thermocouple is square.

[0011] The application further discloses a working method of the thermal wind speed and direction sensor based on thermistor and thermocouple.

[0012] The measurement and control IC controls the power of the heating resistor, so that the heating resistor is warmed up and is higher than the ambient temperature; when there is no wind, a uniform and symmetric heat field is generated around the heating resistor; the thermocouple temperature measurement structure and the thermistor Wheatstone full-bridge temperature measurement structure measure that the temperature difference is zero and no signal is output; when the flow field changes, the heat field is deviated, the thermocouple temperature measurement structure and the thermistor Wheatstone full-bridge temperature measurement structure measure the temperature difference in the direction, the measurement and control IC detects the electrical signals output by the two structures of the orthogonal thermocouple temperature measurement structure and the orthogonal Wheatstone full-bridge temperature measurement structure and converts the electrical signals into the wind speed in the corresponding direction, performs vector calculation on the wind speed measured by the two orthogonal thermocouple temperature measurement structures and the wind speed measured by the two orthogonal thermistor Wheatstone full-bridge temperature measurement structures respectively, and obtains two pairs of wind speed and wind direction information; since the temperature difference directions measured by the thermocouple temperature measurement structure and the thermistor Wheatstone full-bridge temperature measurement structure outside the two parallel sides of the heating resistor are perpendicular, the covered areas and the positions of the two structures are different, if the wind speed measured by the thermocouple temperature measurement structure is v1, the wind direction is θ1, the wind speed measured by the thermistor Wheatstone full-bridge temperature measurement structure is v2, and the wind direction is θ2, v=(v1+v2) / 2 and θ=(θ1+θ2) / 2 are taken as the finally measured wind speed and wind direction.

[0013] The thermal wind speed and direction sensor based on thermistor and thermocouple and the working method thereof have the following advantages:

[0014] The heat thermoelectricity pile of the application is located outside the heating resistance. The voltage signals measured by the two sets of heat thermoelectricity piles in quadrature and the voltage signals measured by the two sets of Wheatstone full-bridge temperature measuring structures composed of the heat thermistors in quadrature are combined by the integrated measurement and control IC to obtain two wind speeds and directions, which are averaged to reduce the measurement error and improve the precision.

[0015] The heat thermistor and the heat thermoelectricity pile can measure the wind speed and direction, and the damage of one does not affect the measurement of the other structure, so the reliability of the sensor is improved. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The application is a thermal wind speed and direction sensor based on heat thermistor and heat thermoelectricity pile;

[0017] The mark in the figure is explained: 1, silicon substrate; 2, heating resistance; 3, heat thermoelectricity pile; 4, heat thermistor; 5, measurement and control IC. DETAILED DESCRIPTION

[0018] In order to better understand the purpose, structure and function of the application, the application of a thermal wind speed and direction sensor based on heat thermistor and heat thermoelectricity pile and its working method are further described in detail below in combination with the drawings.

[0019] As shown in the thermal wind speed and direction sensor based on heat thermistor and heat thermoelectricity pile, it comprises a silicon substrate 1, a heating resistance 2, a heat thermoelectricity pile 3, a heat thermistor 4 and a measurement and control IC 5. Figure 1 The heating resistance 2 is square and located at the center of the silicon substrate 1. Two heat thermistors 4 and one heat thermoelectricity pile 3 are parallelly distributed outside the four edges of the heating resistance 2, and the heat thermoelectricity pile 3 is located outside the heat thermistor 4. Two heat thermistors 4 and one heat thermoelectricity pile 3 are parallelly distributed outside the four edges of the heating resistance 2, and the heat thermoelectricity pile 3 is located outside the heat thermistor 4. The heat thermoelectricity piles 3 on both sides of the upper and lower parallel edges of the heating resistance 2 are connected in series to form a heat thermoelectricity pile temperature measuring structure, and the heat thermoelectricity piles 3 on both sides of the left and right parallel edges of the heating resistance 2 are connected in series to form a heat thermoelectricity pile temperature measuring structure. The two heat thermoelectricity pile temperature measuring structures are in quadrature. The upper four heat thermistors form a Wheatstone full-bridge temperature measuring structure, and the left four heat thermistors form a Wheatstone full-bridge temperature measuring structure. The two Wheatstone full-bridge temperature measuring structures are in quadrature. The measurement and control IC 5 is located at the four corners of the substrate and is centrally symmetrically distributed. The temperature measuring structure composed of the heating resistance 2, the heat thermoelectricity pile 3 and the heat thermistor 4 is monolithically integrated with the measurement and control IC 5, realized by CMOS technology and connected by metal layer lead interconnection.

[0020]

[0021] ​The arrangement direction of the thermoelectric pile 3 is parallel to the edge of the silicon substrate 1, and the hot end and the cold end are located on both sides of the arrangement direction of the thermoelectric pile 3; the thermoelectric pile 3 is close to the edge of the substrate. The thermoelectric pile 3 is square.

[0022] The working method of the application is as follows: the measurement and control IC 5 controls the power of the heating resistor 2 to make the heating resistor 2 warm up and be higher than the ambient temperature; when there is no wind, a uniform and symmetrical heat field is generated around the heating resistor 2; the thermoelectric pile temperature measurement structure and the thermistor Wheatstone full-bridge temperature measurement structure measure that the temperature difference is zero and no signal is output; when the flow field changes and the heat field deviates, the thermoelectric pile temperature measurement structure and the thermistor Wheatstone full-bridge temperature measurement structure measure that the temperature difference in the direction is generated, the measurement and control IC 5 detects the electrical signals output by the two structures of the orthogonal thermoelectric pile temperature measurement structure and the orthogonal thermistor Wheatstone full-bridge temperature measurement structure and converts them into the wind speed in the corresponding direction, and the wind speed measured by the two orthogonal thermoelectric pile temperature measurement structures and the wind speed measured by the orthogonal thermistor Wheatstone full-bridge temperature measurement structure are respectively subjected to vector calculation to obtain two pairs of wind speed and wind direction information; since the temperature difference directions measured by the thermoelectric pile temperature measurement structure and the thermistor Wheatstone full-bridge temperature measurement structure outside the two parallel sides of the heating resistor 2 are perpendicular, the covered areas and the positions of the two structures are different, if the wind speed measured by the thermoelectric pile temperature measurement structure is v1, the wind direction is θ1, the wind speed measured by the thermistor Wheatstone full-bridge temperature measurement structure is v2, and the wind direction is θ2, v=(v1+v2) / 2 and θ=(θ1+θ2) / 2 are taken as the finally measured wind speed and wind direction, the measurement error can be reduced and the measurement accuracy can be improved.

[0023] The thermoelectric pile 3 is located outside the heating resistor 2, the thermoelectric pile 3 is square, and the thermistor 4 is of any shape. The voltage signals measured by the two orthogonal groups of thermoelectric pile temperature measurement structures and the voltage signals measured by the two orthogonal groups of thermistor Wheatstone full-bridge temperature measurement structures can be respectively obtained by vector combination calculation of the integrated measurement and control IC, and the measurement error can be reduced and the accuracy can be improved by averaging the two wind speeds and wind directions. The thermistor and the thermoelectric pile temperature measurement structure can measure the wind speed and wind direction, and the damage of one of them does not affect the measurement of the other structure, and the two structures are redundant to each other, thereby improving the reliability of the sensor. The temperature measurement structure and the measurement and control IC are monolithically integrated, thereby reducing the volume, power consumption and manufacturing cost.

[0024] It can be understood that the application is described by some embodiments, and those skilled in the art know that various changes or equivalent replacements can be made to the features and embodiments without departing from the spirit and scope of the application. In addition, the features and embodiments can be modified to adapt to specific conditions and materials under the guidance of the application without departing from the spirit and scope of the application. Therefore, the application is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of the application belong to the scope of protection of the application.

Claims

1. A thermal wind speed and direction sensor based on a thermistor and a thermopile, characterized in that, The device includes a silicon substrate (1); a heating resistor (2), a thermopile (3), a thermistor (4), and a measurement and control IC (5) are integrated on the silicon substrate (1); the heating resistor (2) is square and located at the center of the silicon substrate (1); two thermistors (4) and a thermopile (3) are distributed parallel to each of the four sides of the heating resistor (2), and the thermopile (3) is located outside the thermistors (4); the thermopiles (3) on the upper and lower parallel sides of the heating resistor (2) are connected in series to form a thermopile temperature measurement structure, and the left and right parallel sides of the heating resistor (2) are connected in series to form a thermopile temperature measurement structure. The thermopile (3) on the side is connected in series to form a thermopile temperature measurement structure, and the two thermopile temperature measurement structures are orthogonal to each other; the four thermistors on the top and bottom form a Wheatstone full-bridge temperature measurement structure, and the four thermistors on the left and right form a Wheatstone full-bridge temperature measurement structure, and the two Wheatstone full-bridge temperature measurement structures are orthogonal to each other; the measurement and control IC (5) is located at the four corners of the substrate and is centrally symmetrically distributed; the temperature measurement structure composed of the heating resistor (2), thermopile (3), and thermistor (4) is monolithically integrated with the measurement and control IC (5), implemented using CMOS technology, and interconnected through metal layer leads; The thermopile (3) is arranged in a direction parallel to the edge of the silicon substrate (1), with the hot and cold ends located on both sides of the arrangement direction of the thermopile (3); the thermopile (3) is close to the edge of the substrate; the thermopile (3) is square.

2. A method for operating the thermal wind speed and direction sensor based on a thermistor and thermopile as described in claim 1, characterized in that, Includes the following steps: The measurement and control IC (5) controls the power of the heating resistor (2), causing the heating resistor (2) to heat up and exceed the ambient temperature; when there is no wind, a uniformly symmetrically distributed heat field is generated with the heating resistor (2) as the center; the temperature difference measured by the thermopile temperature measurement structure and the thermistor Wheatstone full-bridge temperature measurement structure is zero, and there is no signal output; when the flow field changes, the heat field shifts, and a temperature difference is generated in the direction measured by the thermopile temperature measurement structure and the thermistor Wheatstone full-bridge temperature measurement structure. The measurement and control IC (5) detects the electrical signals output by the orthogonal thermopile temperature measurement structure and the orthogonal Wheatstone full-bridge temperature measurement structure and converts them into wind speeds in the corresponding directions. The wind speeds measured by the two thermopile temperature measurement structures and the wind speeds measured by the orthogonal thermistor Wheatstone full-bridge temperature measurement structures are vector-calculated to obtain two pairs of wind speed and wind direction information. Since the temperature difference measured by the thermopile temperature measurement structure outside the two parallel sides of the heating resistor (2) is perpendicular to the direction of the temperature difference measured by the thermistor Wheatstone full-bridge temperature measurement structure, the coverage area and location of the two structures are different. If the wind speed measured by the thermopile temperature measurement structure is v1 and the wind direction is θ1, and the wind speed measured by the thermistor Wheatstone full-bridge temperature measurement structure is v2 and the wind direction is θ2, take v=(v1+v2) / 2 and θ=(θ1+θ2) / 2 as the final measured wind speed and wind direction.

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