Two-dimensional capacitive differential MEMS wind speed and direction sensor

Abstract

The present invention discloses a two-dimensional capacitance differential MEMS wind speed and direction sensor, the sensor comprising a substrate, a rigid support column, a flexible wind sensing column, a rigid connector, a movable electrode plate, a fixed electrode plate, and a metal lead-out electrode; the movable electrode plate and two symmetrical fixed electrode plates form a group of capacitance differential pairs, and four groups of capacitance differential pairs are centrally symmetrically distributed around the flexible wind sensing column on the substrate; the wind blows the flexible wind sensing column to drive the movable electrode plate to produce displacement, and the spacing between the movable electrode plate and the fixed electrode plate changes accordingly, thereby causing the difference of the four groups of capacitance differential pairs to change, and the difference of the four groups of capacitance differential pairs can be measured to obtain wind speed and wind direction information. The two-dimensional capacitance differential wind speed and direction sensor structure proposed by the present invention can improve the reliability and sensitivity of the sensor and reduce power consumption.

Description

Technical Field

[0001] The present invention belongs to the technical field of micro-electromechanical systems (MEMS), and in particular, relates to a two-dimensional capacitive differential MEMS wind speed and direction sensor. Background Art

[0002] Wind speed is a crucial part of meteorological information detection. Wind speed sensors use some principles to convert the physical signals of wind speed and wind direction into electrical signal outputs. According to different measurement principles, wind speed sensors can be divided into mechanical, ultrasonic, thermal, and capacitive types. Mechanical wind speed sensors have a simple structure and low price, but the mechanical parts are prone to wear, the measurement function is limited by environmental factors, and the maintenance cost is high; ultrasonic wind speed sensors have high measurement accuracy, but it is difficult to achieve miniaturization; thermal wind speed sensors are small in size, high in accuracy and sensitivity, but the higher temperature field will cause the sensor chip to consume too much power; capacitive wind speed sensors can be miniaturized, and the power consumption is low while meeting the measurement accuracy and sensitivity requirements. Summary of the invention

[0003] Purpose of the invention: The present invention proposes a two-dimensional capacitive differential MEMS wind speed and direction sensor, which has a simple measurement principle and is easy to implement, and can achieve accurate measurement of wind speed and direction in a two-dimensional plane under low power consumption requirements.

[0004] Technical solution:

[0005] A two-dimensional capacitive differential MEMS wind speed and direction sensor, characterized in that: the sensor comprises a substrate, a rigid support column, a flexible wind sensing column, a rigid connector, a movable electrode plate, a fixed electrode plate, a first metal lead-out electrode, and a second metal lead-out electrode;

[0006] The substrate, rigid support column, flexible wind-sensing column and rigid connector are insulators. The rigid support column is fixed at the center of the upper surface of the substrate. The flexible wind-sensing column is coaxially connected to the rigid support column at the upper part of the rigid support column. Four rigid connectors are symmetrically distributed at the center of the lower part of the column of the flexible wind-sensing column. Four movable electrode plates are connected to the flexible wind-sensing column through the rigid connector. Two fixed electrode plates are symmetrically distributed and fixed on the substrate at a certain air gap from the movable electrode plate. The two fixed electrode plates and the movable electrode plate constitute a group of capacitance differential pairs. The four groups of capacitance differential pairs are symmetrically distributed around the center of the flexible wind-sensing column. The first metal lead-out electrode leads the four movable electrode plates along the rigid connector and the rigid support column and fixes them to the upper surface of the substrate. The second metal lead-out electrodes of the eight fixed electrode plates are distributed on the upper surface of the substrate.

[0007] Furthermore, since the boundary of the fixed electrode plate can completely contain the maximum displacement of the movable electrode plate caused by the flexible wind sensing column when measuring wind speed and wind direction, it is ensured that the plate facing area of ​​the four sets of capacitor differential pairs always remains unchanged. The swing of the flexible wind sensing column against the wind only causes the distance between the plates of the four sets of capacitor differential pairs to change. The two sets of capacitor differential pairs distributed in the NS direction and the two sets of capacitor differential pairs distributed in the WE direction are independent of each other and do not interfere with each other when measuring wind speed and wind direction.

[0008] The present invention also provides a speed measurement method based on the above-mentioned two-dimensional capacitance differential MEMS wind speed and direction sensor, characterized in that a plane rectangular coordinate system is established with the center of the upper surface of the substrate (1) as the origin; the wind speed and direction components in the x-axis and y-axis directions are calculated by reading the changes in the differences of four sets of capacitance differential pairs, and the wind speed and direction on the two-dimensional plane are calculated based on the vector synthesis principle.

[0009] Furthermore, wind in the NS direction causes the difference of the capacitance differential pair in the WE direction to change, and the absolute value of the difference has a one-to-one correspondence and is proportional to the wind speed; wind in the WE direction causes the difference of the capacitance differential pair in the NS direction to change; the wind direction is determined by the tangent ratio of the difference between the capacitance differential pairs in the NS direction and the WE direction.

[0010] Beneficial effects:

[0011] The present invention realizes a two-dimensional wind speed and direction sensor based on a capacitive sensitive structure. The sensor first converts the physical signals of wind speed and wind direction into the physical displacement of a flexible wind sensing column and a movable electrode plate and then converts it into a capacitance change value, and then uses a capacitance differential method to improve the sensitivity of wind speed and wind direction measurement. The sensitive structure of the sensor is composed of an electrode plate, and the capacitor is a passive component without DC power consumption, so the power consumption of the sensor of the present invention is extremely low. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the structure of the MEMS wind speed and direction sensor of the present invention;

[0013] Figure 2 is a top view of the MEMS wind speed and direction sensor of the present invention;

[0014] Figure 3 is a cross-sectional view of the MEMS wind speed and direction sensor of the present invention along the x direction;

[0015] Figure 4 It is a cross-sectional view of the MEMS wind speed and direction sensor of the present invention along the y direction. DETAILED DESCRIPTION

[0016] The present invention will be further explained below in conjunction with the accompanying drawings.

[0017] like Figure 1, Figure 2 , Figure 3 , Figure 4 The two-dimensional capacitive differential wind speed and direction sensor shown includes a substrate 1, a rigid support column 2, a flexible wind sensing column 3, a rigid connector 4, a movable electrode plate 5, a fixed electrode plate 6, a first metal lead-out electrode 7, and a second metal lead-out electrode 8;

[0018] The substrate 1, rigid support column 2, flexible wind sensing column 3 and rigid connector 4 are insulators. The rigid support column 2 is fixed at the center of the upper surface of the substrate 1, and the flexible wind sensing column 3 is coaxially connected to the rigid support column 2 at the upper part of the rigid support column 2; four rigid connectors 4 are symmetrically distributed at the center of the lower part of the column of the flexible wind sensing column 3, and four movable electrode plates 5 are connected to the flexible wind sensing column 3 through the rigid connector 4; two fixed electrode plates 6 are symmetrically distributed and fixed on the substrate 1 at a certain air gap away from the movable electrode plate 5, and the two fixed electrode plates 6 and the movable electrode plate 5 constitute a group of capacitance differential pairs, and the four groups of capacitance differential pairs are symmetrically distributed around the center of the flexible wind sensing column 3; the first metal lead-out electrode 7 leads the four movable electrode plates 5 along the rigid connector 4 and the rigid support column 2 and fixes them to the upper surface of the substrate 1, and the second metal lead-out electrodes 8 of the eight fixed electrode plates 6 are distributed on the upper surface of the substrate 1.

[0019] The fixed electrode plate 61 and the movable electrode plate 51 form a first capacitor C1, the fixed electrode plate 62 and the movable electrode plate 51 form a second capacitor C2, and the first capacitor C1 and the second capacitor C2 constitute a first group of capacitor differential pairs; the fixed electrode plate 63 and the movable electrode plate 52 form a first capacitor C3, the fixed electrode plate 64 and the movable electrode plate 52 form a second capacitor C4, and the first capacitor C3 and the second capacitor C4 constitute a second group of capacitor differential pairs; the fixed electrode plate 65 and the movable electrode plate 53 form a first capacitor C5, the fixed electrode plate 66 and the movable electrode plate 53 form a second capacitor C6, and the first capacitor C5 and the second capacitor C6 constitute a third group of capacitor differential pairs; the fixed electrode plate 67 and the movable electrode plate 54 form a first capacitor C7, the fixed electrode plate 68 and the movable electrode plate 54 form a second capacitor C8, and the first capacitor C7 and the second capacitor C8 constitute a fourth group of capacitor differential pairs.

[0020] When the sensor measures wind speed and wind direction, the boundary of the fixed electrode plate 6 can completely contain the maximum displacement of the movable electrode plate 5 caused by the flexible wind sensing column 3, thereby ensuring that the area of ​​the plates facing each other of the four sets of capacitor differential pairs always remains unchanged. The swing of the flexible wind sensing column 3 against the wind only causes the spacing between the plates of the four sets of capacitor differential pairs to change. The two sets of capacitor differential pairs distributed in the NS direction and the two sets of capacitor differential pairs distributed in the WE direction are independent of each other and do not interfere with each other when measuring wind speed and wind direction.

[0021] When the two-dimensional capacitance differential wind speed and direction sensor of the above structure is working, the capacitance differential pair difference is the difference between the first capacitance and the second capacitance, and the wind speed and direction components in the x-axis and y-axis directions are calculated by reading the changes in the differences of the four sets of capacitance differential pairs. The wind speed and wind direction on the two-dimensional plane are calculated based on the vector synthesis principle. The two-dimensional plane is represented by the x-axis and the y-axis, and the angle between the x-axis and the y-axis is 90 degrees.

[0022] When the wind propagates from the positive direction of the x-axis to the negative direction of the x-axis, the rigid support column 2 is fixed, the flexible wind-sensing column 3 twists toward the negative direction of the x-axis, and the movable electrode plate 51 moves with the flexible wind-sensing column 3, wherein the movable electrode plate 51 of the first group of capacitance differential pairs moves toward the negative direction of the x-axis, the plate facing area and the spacing between the first capacitor C1 and the second capacitor C2 remain unchanged, and the difference of the first group of capacitance differential pairs remains zero; the movable electrode plate 52 of the second group of capacitance differential pairs moves toward the negative direction of the x-axis, the plate facing area between the first capacitor C3 and the second capacitor C4 remains unchanged, the plate spacing of the first capacitor C3 decreases, resulting in an increase in the first capacitor C3, and the plate spacing of the second capacitor C4 increases, resulting in the second capacitor C4 increasing. The second capacitor C4 decreases, and the difference of the second group of capacitor differential pairs increases. The greater the difference change, the greater the wind speed; the movable electrode 53 of the third group of capacitor differential pairs moves toward the negative direction of the x-axis, and the plate facing area and spacing between the first capacitor C5 and the second capacitor C6 remain unchanged, and the difference of the third group of capacitor differential pairs remains zero; the movable electrode plate 54 of the fourth group of capacitor differential pairs moves toward the negative direction of the x-axis, and the plate facing area between the first capacitor C7 and the second capacitor C8 remains unchanged. The plate spacing of the first capacitor C7 decreases, resulting in an increase in the first capacitor C7, and the plate spacing of the second capacitor C8 increases, resulting in a decrease in the second capacitor C8. The difference of the fourth group of capacitor differential pairs increases, and the greater the difference change, the greater the wind speed.

[0023] Similarly, when the wind propagates from the negative direction of the x-axis to the positive direction of the x-axis, the difference of the first group of capacitor differential pairs remains zero; the difference of the second group of capacitor differential pairs decreases; the difference of the third group of capacitor differential pairs remains zero; and the difference of the fourth group of capacitor differential pairs decreases.

[0024] The sensor of the present invention has the same working principle in the x direction and the y direction. When the wind propagates from the negative direction of the y axis to the positive direction of the y axis, the difference of the first group of capacitance differential pairs increases; the difference of the second group of capacitance differential pairs remains zero; the difference of the third group of capacitance differential pairs increases; and the difference of the fourth group of capacitance differential pairs remains zero. Similarly, when the wind propagates from the positive direction of the y axis to the negative direction of the y axis, the difference of the first group of capacitance differential pairs decreases; the difference of the second group of capacitance differential pairs remains zero; the difference of the third group of capacitance differential pairs decreases; and the difference of the fourth group of capacitance differential pairs remains zero.

[0025] When there is wind propagation along the negative direction of the x-axis and the negative direction of the y-axis, the flexible wind sensing column 3 twists with the wind, and the four movable electrode plates 5 are displaced along the negative direction of the x-axis and the negative direction of the y-axis, respectively, resulting in a decrease in the difference of the first group of capacitance differential pairs, an increase in the difference of the second group of capacitance differential pairs, a decrease in the difference of the third group of capacitance differential pairs, and an increase in the difference of the fourth group of capacitance differential pairs. Since the rigid connector 4 can not be relatively displaced with the flexible wind sensing column 3 when the flexible wind sensing column 3 twists, the difference of the first group of capacitance differential pairs changes in the same way as the difference of the third group of capacitance differential pairs. Similarly, the difference of the second group of capacitance differential pairs changes in the same way as the difference of the fourth group of capacitance differential pairs. The larger the ratio of the change in the difference of the first group of capacitance differential pairs to the change in the difference of the second group of capacitance differential pairs, the smaller the angle between the wind and the negative direction of the y-axis, and vice versa. The greater the vector sum of the difference change of the first group of capacitance differential pairs and the difference change of the second group of capacitance differential pairs, the greater the wind speed, and vice versa, the smaller the wind speed.

[0026] The basic working principle of the present invention is that the wind to be measured blows the flexible wind sensing column 3 to cause the movable electrode plate 5 to displace, and the distance between the movable electrode plate 5 and the fixed electrode plate 6 changes accordingly, thereby causing the difference between the four groups of capacitor differential pairs to change. By measuring the difference between the four groups of capacitor differential pairs, the wind speed and wind direction information can be obtained.

[0027] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A two-dimensional capacitive differential MEMS wind speed and direction sensor, characterized in that: The sensor comprises a substrate (1), a rigid support column (2), a flexible wind sensing column (3), a rigid connector (4), a movable electrode plate (5), a fixed electrode plate (6), a first metal lead-out electrode (7), and a second metal lead-out electrode (8); The substrate (1), the rigid support column (2), the flexible wind sensing column (3) and the rigid connector (4) are insulators; the rigid support column (2) is fixed at the center of the upper surface of the substrate (1); the flexible wind sensing column (3) is coaxially connected to the rigid support column (2) at the upper part of the rigid support column (2); four rigid connectors (4) are symmetrically distributed at the center of the lower part of the column of the flexible wind sensing column (3); four movable electrode plates (5) are connected to the flexible wind sensing column (3) via the rigid connector (4); each movable electrode plate (5) Two fixed electrode plates (6) fixed on the substrate (1) are symmetrically arranged at intervals on both sides, the two fixed electrode plates (6) and the movable electrode plate (5) form a group of capacitance differential pairs, and the four groups of capacitance differential pairs are symmetrically distributed around the center of the flexible wind sensing column (3); the first metal lead-out electrode (7) leads the four movable electrode plates (5) along the rigid connector (4) and the rigid support column (2) and fixes them on the upper surface of the substrate (1), and the second metal lead-out electrodes (8) of the eight fixed electrode plates (6) are distributed on the upper surface of the substrate (1).

2. The two-dimensional capacitive differential MEMS wind speed and direction sensor according to claim 1, characterized in that: When measuring wind speed and wind direction, the distance between the movable electrode plate (5) and the fixed electrode plates (6) on both sides thereof includes the maximum displacement of the movable electrode plate (5) along with the flexible wind sensing column (3), thereby ensuring that the facing areas of the plates of the four sets of capacitor differential pairs remain unchanged.

3. The two-dimensional capacitive differential MEMS wind speed and direction sensor according to claim 1, characterized in that: The swinging of the flexible wind sensing column (3) against the wind only causes the distance between the plates of the four groups of capacitor differential pairs to change, and the two groups of capacitor differential pairs distributed in the NS direction and the two groups of capacitor differential pairs distributed in the WE direction are independent of each other and do not interfere with each other when measuring wind speed and wind direction.

4. A speed measurement method based on the two-dimensional capacitive differential MEMS wind speed and direction sensor according to claim 1, characterized in that: A plane rectangular coordinate system is established with the center of the upper surface of the substrate (1) as the origin; the wind speed and direction components in the x-axis and y-axis directions are calculated by reading the changes in the differences of four sets of capacitance differential pairs, and the wind speed and direction in the two-dimensional plane are calculated based on the vector synthesis principle.

5. The speed measurement method according to claim 4, characterized in that: Wind in the NS direction causes the difference of the capacitance differential pair in the WE direction to change, and the absolute value of the difference has a one-to-one correspondence and is proportional to the wind speed; wind in the WE direction causes the difference of the capacitance differential pair in the NS direction to change, and the wind direction is determined by the tangent ratio of the difference between the capacitance differential pairs in the NS direction and the WE direction.

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