JPH04127575U - Acceleration detection device - Google Patents

Abstract

(57) [Summary] [Purpose] To provide an acceleration detection device that is capable of highly sensitive acceleration detection and has robustness. [Structure] A through hole 101 is formed in the center of the support substrate 100, and a lower housing 110 is bonded to the lower surface of the through hole 101.
The first room R1 is connected to the upper surface of the upper housing 1.
20 respectively form a second room R2. A bowl-shaped diaphragm 130 is installed in the second chamber, and a weight body 14 is connected to the center of the bowl-shaped diaphragm 130 via a joining member 141.
0 is hanging in the air. Inside the first room R1,
Filled with damping oil. Displacement electrodes 21, 23, 2 are disposed on the displacement substrate 150 joined to the diaphragm.
5 is formed, and the upper housing 120 is opposite to this.
Fixed electrodes 11,
13 and 15 are formed. Three-dimensional acceleration acting on the weight body can be detected from changes in the capacitance of the opposing electrodes.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention is based on an acceleration detection device, in particular, a change in capacitance between a pair of electrodes. The present invention relates to an acceleration detection device that detects applied force.

0002

[Conventional technology]

In the automobile and machinery industries, acceleration detection devices that can accurately detect applied forces are used. Demand for storage facilities is increasing. In particular, it detects the acceleration acting on each three-dimensional component. There is a need for a small and efficient device.

0003 To meet this demand, gauge resistors are formed on semiconductor substrates such as silicon. The piezoresistive effect reduces the mechanical strain that occurs on the board due to external forces. An acceleration detection device has been proposed that utilizes this to convert into an electrical signal. However, this Detection devices using gauge resistors are expensive to manufacture and require temperature compensation. There is a problem. Therefore, in the specification of Japanese Patent Application No. 2-274299, the capacitance A new acceleration detection device that utilizes changes in quantity has been proposed. This new acceleration The detection device uses a fixed electrode formed on a fixed substrate and a device that generates displacement due to the action of force. A capacitive element is constructed by the displacement electrode and the capacitive element. Based on this, each of the three-dimensional components of the applied force can be detected. In addition, the patent application Hei 2- 416188 discloses a method for manufacturing this novel acceleration detection device, In the specification of PCT/JP91/00428 related to the international application based on the Patent Cooperation Treaty discloses a method for testing this new acceleration detection device.

0004

[Problem that the idea aims to solve]

However, the new acceleration detection device that uses the change in capacitance mentioned above has , it is difficult to manufacture a device that satisfies both robustness and high sensitivity. There is a problem. Demand for acceleration detection devices has increased in recent years, especially in automobiles. In recent years, devices that are capable of high-sensitivity acceleration detection and are robust are becoming increasingly popular. placement is desired. However, the sensitivity of conventionally proposed acceleration detection devices is limited. In order to improve this, it is necessary to have a structure that can deflect even when a minute acceleration is applied. Therefore, the robustness will be reduced.

[0005] Therefore, the present invention was developed to enable highly sensitive acceleration detection and to provide robust acceleration. An object of the present invention is to provide a speed detection device.

[0006]

[Means to solve the problem]

(1) The first invention of the present application is an acceleration detection device that includes: A support board with a through hole in the center, a lower casing joined to the lower surface of the support substrate and forming a first chamber therein; an upper casing joined to the upper surface of the support substrate and forming a second chamber therein; In the second chamber, a diaphragm attached to the upper surface of the support substrate; a weight body housed in the first room at a predetermined distance from the wall of the room; It is inserted into the through hole of the support board, one end is connected to the weight body, and the other end is connected to the diaphragm. a joining member joined to the lower surface; a displacement substrate bonded to the top surface of the diaphragm; is installed, and the acceleration acting on the weight body is transferred between the displacement board and a predetermined fixed surface inside the upper housing. It is designed so that it can be detected as a change in the distance between.

[0007] (2) The second invention of the present application is, in the above-mentioned acceleration detection device, An auxiliary board fixed to the upper housing is further provided between the diaphragm and the displacement board, The displacement board is attached to the diaphragm by the joining member inserted through the through hole formed in this auxiliary board. indirectly connected to the ram, Detecting external forces by considering the change in distance between the displacement board and the auxiliary board This is how it was done.

[0008]

[Effect]

In the acceleration detection device of the present invention, the weight body is placed in the first chamber by the joining member. It becomes suspended from the diaphragm. When acceleration acts on the weight body, the die Due to the deformation of the yaphram, the weight body is displaced within the first chamber. Weight body and first part There is a predetermined distance between it and the wall of the building. Therefore, the displacement of the weight body is It is limited to this predetermined interval. Therefore, if excessive acceleration is applied Even if can be protected. Therefore, it can be used in harsh environments such as when installed in a car. Sufficient robustness can be ensured even under

[0009] The displacement of the weight body is transmitted to the displacement substrate joined to the diaphragm. displacement The substrate 150 produces a displacement corresponding to the direction and magnitude of the applied acceleration. Therefore, the change in distance between a given fixed surface in the upper housing and the displacement board, e.g. If detected as a change in capacitance, the direction and magnitude of the applied acceleration can be detected. can. Diaphragms are deformed even by the action of relatively small forces, so Very sensitive detection is possible.

0010 In addition, by performing detection that takes into account changes in the distance between the displacement board and the auxiliary board, This enables highly accurate detection.

[0011]

【Example】

Hereinafter, the present invention will be described based on illustrated embodiments. Figure 1 is an example of the present invention. It is a side sectional view of the acceleration detection device concerning this. The support substrate 100 has a through hole 1 in the center. 01, and a screw hole 102 is formed at the end. This one Insert a screw into the fixing hole 102, and place this device at a predetermined position on the object to be inspected, such as an automobile. Fix it in place. A lower housing 110 is bonded to the lower surface of the support substrate 100, A first room R1 is formed inside. Further, on the upper surface of the support substrate 100, an upper The housing 120 is joined, and a second room R2 is formed inside. this In the device of the embodiment, any of the support substrate 100, the lower housing 110, and the upper housing 120 It is also made of metal.

0012 Inside the second room R2, a bowl-shaped diaphragm is placed face down on the top surface of the support substrate 100. 130 is attached. In this example, the diaphragm is made of phosphor bronze. 130. The diaphragm 130 has a bowl-like overall shape, Each part has a wavy structure. A bowl-shaped diaphragm with a wave shape like this is effective in increasing detection sensitivity. If you prefer lower sensitivity, use flat A plate-shaped diaphragm may be used. Inside the first room R1, there are walls and The weight bodies 140 are housed so as to maintain a predetermined interval. The weight body 140 is In the example, it has a cylindrical shape, and the side and bottom surfaces are connected to the bottom at a predetermined interval. It is surrounded by the inner wall of the casing 110, and the upper surface is opposite to the lower surface of the support substrate 100. They are arranged at predetermined intervals. The joining member 141 inserted through the through hole 101 The weight body 140 is joined to the center of the lower surface of the diaphragm 130. However, Therefore, the weight body 140 is suspended in the center of the lower surface of the diaphragm 130. ing.

[0013] When acceleration acts on the weight body 140, the force due to this acceleration acts on the joining member 141. as a result, the diaphragm 130 deforms. will occur. In the end, the weight body 140 is I'm going to exercise. In order to make the movement of the weight body 140 smooth, the equipment of this embodiment is In the installation, the spaces between the first room R1 and the second room R2 are filled with damping oil. It has been filled. Note that when each chamber is completely filled with oil, the oil expands thermally. Sometimes there is a risk of leakage to the outside. Therefore, it is actually partially filled with gas. is preferable.

[0014] The displacement caused by the acceleration acting on the weight body 140 is displaced from the diaphragm 130. is transmitted to the displacement board 150 via the joining member 142. Therefore, the displacement substrate 150 produces a displacement corresponding to the direction and magnitude of the applied acceleration. So Here, the change in the distance between the predetermined fixed surface in the upper housing 120 and the displacement board 150 is If detected, the direction and magnitude of the applied acceleration can be detected.

[0015] This device makes it possible to detect this change in distance as a change in capacitance. ing. That is, five displacement electrodes 21 to 25 (as shown in FIG. (of which only three are shown), and the inner bottom surface of the upper housing 120 has a , five fixed electrodes 11 to 15 are connected via an insulating layer 160 (only three of these are shown in FIG. is shown). The insulating layer 160 was formed as described above. This is because the upper housing 120 is made of metal. In this embodiment, displacement substrate 150 is made of an insulator, but if the displacement board 150 is made of metal, an insulating layer Displacement electrodes 21 to 25 are formed through these. In this way, the displacement substrate and By forming five pairs of electrodes each consisting of a fixed substrate and a fixed substrate, the capacitance of each pair of electrodes can be reduced. Based on the change, a change in the inter-electrode distance can be detected. In other words, the weight body 140 can be detected. This detection principle will be explained later. Explain.

[0016] An acceleration detection device with such a structure has considerable robustness and , highly sensitive acceleration detection is possible. When acceleration acts on the weight body 140, the Due to the deformation of the earphragm 130, the weight body 140 is displaced within the first chamber. heavy A predetermined distance is provided between the weight body 140 and the wall surface of the first room R1. did Therefore, the displacement of the weight body 140 is limited to this predetermined interval. parable For example, even if the weight body 140 attempts to displace beyond a predetermined limit in the left-right direction in the figure, the lower casing Such an excessive displacement is not possible because it will collide with the side inner wall of the body 110. stomach. Similarly, even if it attempts to displace upward, it will collide with the lower surface of the support substrate 100 and move downward. Even if it tries to be displaced in this direction, it collides with the bottom inner wall of the lower casing 110. For this reason, Even if excessive acceleration is applied, the displacement of the weight body 140 will not exceed the limit. There is no sharp edge, and the diaphragm 130 can be protected from damage. therefore, It can ensure sufficient robustness even under harsh environments such as when installed in a car.

[0017] In this way, the diaphragm 130 is never subjected to any force that would cause excessive displacement. Since no force is applied to it, it is a delicate damascene that has a thin wall and is flexible even in the face of minute forces. Even with the use of earphragms, breakage problems do not arise. Therefore, such a delicate By using a diaphragm, highly sensitive detection becomes possible. Additions related to this invention The speed detection device is characterized by its robustness and highly sensitive detection. The point is that you can.

[0018] FIG. 2 shows a diaphragm 13 used in an acceleration detection device according to another embodiment of the present invention. 5 is a top view of FIG. This diaphragm 135 is similar to the bowl-shaped diaphragm 1 shown in FIG. 30, with quadrant-shaped through holes H1 to H4 formed therein. In other words, diamond Diaphragm 135 can be created by cutting out four quarter circles of flamm 130. is obtained. By providing four through holes H1 to H4, the bridge parts B1 to B4 are It is formed. The center part where the joining member 142 is joined is the four bridge parts B1 ~ Since it will be supported by B4, the flexibility will be further increased and the sensitivity will be higher. This allows for better detection. In addition, since the through holes H1 to H4 were opened, the first room R1 As the weight body 140 is displaced, the damping oil inside the through holes H1 to Move through H4 to the second room R2.

[0019] The acceleration detection device shown in Figure 1 detects acceleration components in all three-dimensional directions. can be detected. Let us explain this detection principle using a simple model shown in Figure 3. . The main components of the model shown in FIG. 3 are a fixed substrate 10, a flexible substrate 20, and an effecting body. 30, and a device housing 40. FIG. 4 shows a bottom view of the fixed substrate 10. Figure 4 FIG. 3 shows a cross section of the fixed substrate 10 taken along the X axis. Fixed board 1 0 is a disk-shaped board as shown in the figure, and the periphery is fixed to the device casing 40. . On this lower surface, fan-shaped fixed electrodes 11 to 14 and a disc-shaped fixed electrode 15 are arranged as shown in the figure. It is formed like this. On the other hand, FIG. 5 shows a top view of the flexible substrate 20. Figure 5 Flexibility A cross section of the substrate 20 taken along the X axis is shown in FIG. The flexible substrate 20 also As shown in the figure, it is a disk-shaped board, and the periphery is fixed to the device housing 40. this On the top surface, fan-shaped displacement electrodes 21 to 24 and a disc-shaped displacement electrode 25 are arranged as shown in the figure. It is formed. The effecting body 30 has a top surface shown in broken lines in FIG. It has a cylindrical shape and is coaxially joined to the lower surface of the flexible substrate 20. Device housing 40 has a cylindrical shape and firmly supports the fixed substrate 10 and the flexible substrate 20. There is. The fixed substrate 10 and the flexible substrate 20 are arranged parallel to each other at a predetermined distance. It is arranged as follows. Both are disk-shaped substrates, but the fixed substrate 10 has high rigidity. In contrast to a substrate that does not easily bend, the flexible substrate 20 has flexibility and does not easily bend when force is applied. This results in a board that bends. The operation of such a model is shown in Figure 1. It can be understood that this is equivalent to the operation of

[0020] Now, as shown in FIG. 3, a point of action P is defined within the action body 30, and this point of action P is Define the XYZ three-dimensional coordinate system as the origin as shown in the figure. In other words, to the right in Figure 3 The Define each. The central part of the flexible substrate 20 to which the effecting body 30 is joined is referred to as an effecting part. , the peripheral part fixed by the device casing 40 is a fixed part, and the part between these parts is a flexible part. , when an external force acts on the effecting body 30, the flexible portion is bent, The acting part will be displaced relative to the fixed part. There is no force acting on the point of action P. In this state, as shown in FIG. 3, the fixed electrodes 11 to 15 and the displacement electrodes 21 to 25 are They maintain a parallel state with a predetermined interval. Now, fixed electrodes 11 to 15 and this The combinations of displacement electrodes 21 to 25 facing each other are capacitive elements C. We will call them 1 to C5. Here, for example, a force Fx in the X-axis direction is applied to the point of application P. When acted upon, this force Fx creates a moment force on the flexible substrate 20, as shown in FIG. As shown in FIG. 2, the flexible substrate 20 will be bent. This deflection causes displacement Although the distance between the electrode 21 and the fixed electrode 11 becomes larger, the distance between the displacement electrode 23 and the fixed electrode 13 increases. The distance between them becomes smaller. Suppose that the force acting on the point of application P is -Fx in the opposite direction. Then, a deflection with the opposite relationship will occur. In this way the force Fx or −Fx acts, a change will appear in the capacitance of capacitive elements C1 and C3. , by detecting this, the force Fx or -Fx can be detected. this When each of the displacement electrodes 22, 24, 25 and that of the fixed electrodes 12, 14, 15 Each interval may become larger or smaller in parts, but overall it will not change. It is safe to assume that it will not change. On the other hand, if a force Fy or -Fy in the Y direction is applied, The distance between the displacement electrode 22 and the fixed electrode 12 and the distance between the displacement electrode 24 and the fixed electrode 14 A similar change occurs only in the interval. In addition, the field where the force Fz in the Z-axis direction acts In this case, as shown in FIG. 7, the distance between the displacement electrode 25 and the fixed electrode 15 becomes smaller; If an opposite force -Fz is applied, this distance will be larger. At this time, the displacement voltage Although the distance between the poles 21 to 24 and the fixed electrodes 11 to 14 also becomes smaller or larger, The change in the distance between the displacement electrode 25 and the fixed electrode 15 is most remarkable. Therefore, this capacity Force Fz or -Fz is detected by detecting the change in capacitance of quantum element C5. can be done.

[0021] Generally, the electrostatic capacitance C of a capacitive element is defined by the electrode area S, the electrode spacing d, and the dielectric constant ε. Then, C=εS/d It is determined by Therefore, when the distance between the opposing electrodes gets closer, the capacitance C increases. , the capacitance C becomes smaller as the distance increases. This acceleration detection device uses this principle Then, the change in capacitance between each electrode is measured, and the action is applied to the point of action P based on this measurement value. It detects the external force caused by the That is, the acceleration in the X-axis direction is the capacitive element C1, Based on the capacitance change between C3, the acceleration in the Y-axis direction is caused by the capacitance change of capacitive elements C2 and C4. Based on A ceremony will take place.

[0022] In reality, force components in each axial direction are detected by a detection circuit as shown in Figure 8. . That is, the capacitance values of capacitive elements C1 to C5 are converted to CV conversion circuits 51 to 51, respectively. 55 into voltage values V1 to V5. Then, the force in the X-axis direction is calculated by the subtractor 6 1 is obtained at the terminal Tx as a differential voltage calculated as (V1-V3), and Y The axial force is the difference voltage obtained by calculating (V2-V4) using the subtracter 62. The force in the Z-axis direction is obtained as a voltage V5 at the terminal Tz. It will be done.

[0023] Next, another example will be given. The embodiment shown in FIG. 9 is an implementation of FIG. The example is further improved to increase the detection accuracy in the Z-axis direction (vertical direction in the figure). da Earphragm 130 and displacement board 150 are connected by a joining member 142. An auxiliary substrate 170 is further provided between the two. The center of this auxiliary board 170 A through hole is formed in the through hole, and the joining member 142 is inserted into this through hole. strange Displacement electrodes 21 to 25 and fixed electrodes 11 to 15 formed on the upper surface of the substrate 150 Therefore, the structure of the capacitive elements C1 to C5 is similar to that of the above embodiment, but this In the embodiment, the displacement electrode 26 formed on the lower surface of the displacement substrate 150 and the auxiliary substrate A capacitive element C6 is constituted by the fixed electrode 16 formed on the upper surface of the capacitor 170. There is. In a detection device with such a configuration, the detected value in the Z-axis direction is shown in Fig. 10. obtained by the circuit. In other words, the capacitance values of capacitive elements C5 and C6 are are converted into voltage values V5 and V6 by paths 55 and 56, and the difference V5 is calculated by a subtracter 63. -V6 is determined, and this is set as the detected value in the Z-axis direction. In this way, regarding detection in the Z-axis direction, However, if the difference is used, the error factors will be canceled out and more accurate detection will be possible. become. Regarding this reason, please refer to the international application PCT/J based on the Patent Cooperation Treaty. It is detailed in §4 of specification P91/00428.

[0024] The present invention has been explained above based on the illustrated embodiments, but the present invention is not limited to these embodiments. The invention is not limited to these examples, and can be implemented in various other ways. Shown in Figure 1 The shape of each part of the acceleration detection device can be changed freely due to the design. For example, the weight body 140 can be made into a sphere or an ellipsoid. Also Also, the number and arrangement of electrodes are not limited to the above-mentioned embodiments. The above fruit In the example, five sets of capacitive elements are configured by five fixed electrodes and five displacement electrodes. However, it is possible to configure five sets of capacitive elements by using one electrode as one common electrode. It doesn't work. Further, five sets of capacitive elements are not necessarily required. 4 sets of capacitive elements It is also possible to perform three-dimensional acceleration detection. Also, two-dimensional or one-dimensional If dimensional acceleration detection is to be performed, two or one set of capacitive elements is sufficient. Also , a method for detecting the displacement state of the displacement substrate 150 is based on capacitance using a capacitive element. The present invention is not limited to methods for detecting changes in . For example, in the device shown in Figure 1 Then, a piezoelectric element is inserted between the fixed electrodes 11 to 15 and the displacement electrodes 21 to 25. If this is done, the distance between the electrodes can be detected using the electromotive force of this piezoelectric element. It is possible.

[0025]

[Effect of the idea]

As described above, the acceleration detection device according to the present invention detects the displacement of the weight body within the first room. The weight body is suspended in the air by a diaphragm and acts on the weight body. This makes it possible to detect acceleration with high sensitivity. , sufficient robustness can be ensured.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of an acceleration detection device according to an embodiment of the present invention.

FIG. 2 is a top view of a diaphragm used in another embodiment of the present invention.

FIG. 3 is a side sectional view of a simple model for explaining the operation of the acceleration detection device shown in FIG. 1;

4 is a bottom view of the fixed substrate 10 in the model shown in FIG. 3. FIG.

5 is a top view of the flexible substrate 20 in the model shown in FIG. 3. FIG.

6 is a side sectional view showing a state in which a force Fx in the X-axis direction is applied to the model shown in FIG. 3; FIG.

7 is a side cross-sectional view showing a state where a force Fz in the Z-axis direction is applied to the model shown in FIG. 3; FIG.

8 is a circuit diagram showing a signal processing circuit used in the acceleration detection device shown in FIG. 1. FIG.

FIG. 9 is a side sectional view of an acceleration detection device according to yet another embodiment of the present invention.

10 is a circuit diagram of a signal processing circuit used in the detection device shown in FIG. 9. FIG.

[Explanation of symbols]

10...Fixed board 11-16...Fixed electrode 20...Flexible board 21-26...Displacement electrode 30...Action body 40...Device housing 51-56...CV conversion circuit 61-63...Subtractor 100...Support substrate 101...Through hole 102...Screw hole 110...Lower housing 120...Upper housing 130, 135...Diaphragm 140... Weight body 141, 142...Joining member 150...Displacement board 160...Insulating layer 170...Auxiliary board B1 to B4...Crosslinked portion H1~H4...Through hole R1...first room R2...Second room

Claims (2)

[Scope of utility model registration request] 1. A support substrate having a through hole in the center, a lower casing bonded to the bottom surface of the support substrate and forming a first chamber therein, and a lower casing bonded to the top surface of the support substrate and having an interior thereof. an upper housing forming a second chamber; a diaphragm attached to the upper surface of the support substrate in the second chamber; A housed weight body, a joining member inserted into the through hole and having one end joined to the weight body and the other end joined to the lower surface of the diaphragm, and a joining member directly or indirectly connected to the upper surface of the diaphragm. a bonded displacement substrate;
An acceleration detection device characterized in that the acceleration acting on the weight body can be detected as a change in distance between the displacement board and a predetermined fixed surface within the upper housing. 2. In the acceleration detection device according to claim 1, an auxiliary board fixed to the upper housing is further provided between the diaphragm and the displacement board, and a joining member is inserted through a through hole formed in the auxiliary board. The displacement substrate is indirectly joined to the diaphragm by a method, and an external force is detected by taking into consideration a change in distance between the displacement substrate and the auxiliary substrate. Device.