JP2012202696A - Capacitance type acceleration sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a capacitance type acceleration sensor with capacitance at a fixed electrode facing a movable electrode, which exhibits no change in the capacitance for the acceleration applied in the direction perpendicular to a detection axis.SOLUTION: A capacitance type acceleration sensor 100 has an electrode cell structure A composed of a first side electrode cell A1 and a second side electrode cell A2. The first side electrode cell A1 comprises a pair of movable electrodes 101a and 101b disposed on a first side of the weight 101, a pair of outer fixed electrodes 111a and 112a which are respectively disposed outside thereof, and a pair of inner fixed electrodes 111b and 112b which are respectively disposed inside thereof. The second side electrode cell A2 comprises a pair of movable electrodes 102a and 102b disposed on a second side of the weight 101, a pair of outer fixed electrodes 121a and 122a which are respectively disposed outside thereof, and a pair of inner fixed electrodes 121b and 122b which are respectively disposed inside thereof.

Description

  The present invention relates to a capacitive acceleration sensor, and more specifically, an electrode arrangement pattern in which a capacitance of a fixed electrode facing a movable electrode does not change when an acceleration is applied in a direction perpendicular to a detection axis. The present invention relates to a differential capacitive acceleration sensor having a structure and a surface MEMS (Micro Electro Mechanical Systems).

  As a conventional capacitive acceleration sensor, for example, a capacitive acceleration sensor using a comb-like electrode as disclosed in Patent Document 1 is known. A differential capacitive acceleration sensor having substantially comb-like electrodes is disclosed in, for example, Patent Document 2.

  FIG. 1 is a configuration diagram for explaining a conventional differential capacitive acceleration sensor disclosed in Patent Document 2. In FIG. Each of the electrodes of this conventional differential capacitive acceleration sensor is formed of a plurality of segments made up of smaller capacitance “cells” each having a plurality of capacitors connected in parallel on a silicon substrate 22. In addition, a suspended polysilicon beam 24 is formed. This beam 24 is placed on the surface of the substrate above the anchors 26A to 26D. The beam 24 is generally H-shaped and has two elongated thin legs 28 and 32 and a transverse central member 34 suspended between them. A pair of beam fingers 36 and 38 hang from the central member 34 in a parallel orientation and across the beam axis. The finger 36 forms one electrode of a parallel plate capacitor having a stationary member 42 as its counter electrode, ie, a plate. Similarly, finger 38 forms one electrode of a second parallel plate capacitor having stationary member 44 as its opposing plate.

  In addition to the above-described patent documents, for example, Patent Documents 3 to 5 disclose capacitive acceleration sensors having comb teeth that are vertically or laterally symmetrical.

JP 2003-248016 A Japanese Patent Publication No. 6-44008 JP 2000-22171 A JP 2005-172543 A JP 2000-1331075 A

  2A to 2C are diagrams for explaining the relationship between the capacitance between the movable electrode and the fixed electrode in the differential capacitance detection type acceleration sensor of FIG. 1, and FIG. 2A is a top view. 2B is a cross-sectional view taken along the line AA ′ in FIG. 2A, and FIG. 2C is a cross-sectional view taken along the line BB ′ in FIG.

In the figure, reference numeral 31 is a set of a plurality of movable electrodes and fixed electrodes (1 cell), 37 is an upper movable electrode, 36 is a lower movable electrode, 43 is an upper fixed electrode (L side), 46 is an upper fixed electrode (R side) ), 42 is a lower fixed electrode (L side), 47 is a lower fixed electrode (R side), and C _{L1 to} C _L4 are an upper movable electrode 37 and a lower movable electrode 36 and an upper fixed electrode (L side) 43 and a lower fixed. The capacitances C _{R1 to} C _R4 formed between the electrode (L side) 42 and the upper movable electrode 37, the lower movable electrode 36, the upper fixed electrode (R side) 46, and the lower fixed electrode (R side) 47 The capacitance formed between the two is shown.

Here, the capacitance between the movable electrode and the fixed electrode with respect to the acceleration detection axis direction, that is, C _L1 , C _L2 , C _R1 , and C _{R2 in} FIG. Capacitance (defined as the main sensitivity capacity section), and the capacity in the direction perpendicular to the detection axis, that is, C _L3 , C _L4 , C _R3 , and C _{R4 in} FIG. (Defined as a sub-sensitivity capacitor). When the gravitational acceleration is not applied (G = 0), the sub-sensitivity capacitance unit becomes (C _L1 + C _L2 + C _L3 + C _L4 ) − (C _R1 + C _R2 + C _R3 + C _R4 ) = 0, and the differential capacitance detection type In the acceleration sensor, since the difference in capacitance is 0, the output is 0 when G = 0, that is, the offset is 0. On the other hand, when acceleration perpendicular to the detection axis direction is applied (G ≠ 0), no capacitance change occurs in C _L1 , C _L2 , C _R1 , C _R2 , so (C _L1 + C _L2 ) − (C _R1 + C _R2 ) = 0, but in C _L3 , C _L4 , C _R3 , C _R4 , (C _L3 + C _L4 ) − (C _R3 + C _R4 ) ≠ 0, and an output that should not be detected is output. This means that there is a problem that when a force is applied in a direction perpendicular to the detection axis, the capacitance changes, and the acceleration of the other axis is erroneously detected. The capacitance change referred to here means that a capacitance difference occurs between the L-side capacitance and the R-side capacitance. This problem occurs because the number and length of the combs of the fixed electrode facing the movable electrode are different from each other.

  The present invention has been made in view of such problems, and the object of the present invention is to change the capacitance of the fixed electrode facing the movable electrode when acceleration is applied in a direction perpendicular to the detection axis. It is an object of the present invention to provide a capacitance type acceleration sensor having an electrode arrangement pattern structure that does not cause the phenomenon.

  The present invention has been made to achieve such an object. The invention according to claim 1 is a comb tooth integrally formed on a weight body provided on a substrate via an elastic member. A capacitance-type acceleration sensor, and a pair of movable electrodes provided at one side of the weight body, A one-side electrode cell comprising a pair of outer fixed electrodes respectively disposed outside the pair of movable electrodes, and a pair of inner fixed electrodes disposed between the pair of movable electrodes; A pair of movable electrodes provided on the other side, a pair of outer fixed electrodes respectively disposed outside the pair of movable electrodes, and a pair of inner fixed electrodes respectively disposed between the pair of movable electrodes The other side electrode cell, the one side electrode cell and the other side electrode cell, Characterized by being configured electrode cell structure. Example 1

  According to a second aspect of the present invention, in the first aspect of the present invention, the pair of movable electrodes are arranged in a direction perpendicular to the longitudinal direction of the weight body.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the one-side electrode cell and the other-side electrode cell are arranged symmetrically with respect to the longitudinal direction of the weight body. It is characterized by being.

  According to a fourth aspect of the present invention, in the first, second, or third aspect of the invention, the pair of movable electrodes of the one-side electrode cell is provided on one side of the weight body. Each of the movable electrode and the second movable electrode, and the pair of outer fixed electrodes includes a first outer fixed electrode and a second outer fixed electrode, which are respectively disposed outside the pair of movable electrodes, The pair of inner fixed electrodes is composed of a second inner fixed electrode and a first inner fixed electrode respectively disposed between the pair of movable electrodes, and the pair of movable electrodes of the other electrode cell, A first outer electrode comprising a first movable electrode and a second movable electrode provided on the other side of the weight body, wherein the pair of outer fixed electrodes are respectively disposed outside the pair of movable electrodes. A fixed electrode and a second outer fixed electrode, wherein the pair of inner fixed electrodes Characterized in that it is composed of a second inner fixed electrode and the first inner fixed electrodes are respectively disposed between a pair of movable electrodes.

  According to a fifth aspect of the present invention, in the fourth aspect of the invention, the first outer fixed electrode and the first inner fixed electrode on the one side are connected, and the second The outer fixed electrode and the second inner fixed electrode are connected, the first outer fixed electrode and the first inner fixed electrode on the other side are connected, and the second outer fixed electrode is connected. An electrode is connected to the second inner fixed electrode.

  The invention according to claim 6 is the invention according to claim 4 or 5, wherein the first outer fixed electrode and the second inner fixed electrode are opposed to each other through the first movable electrode. The second outer fixed electrode and the first inner fixed electrode are arranged to face each other via the second movable electrode.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein a plurality of the electrode cell structures are continuously arranged along a longitudinal direction of the weight body. It is characterized by.

  The invention according to claim 8 is the invention according to any one of claims 1 to 7, characterized in that the longitudinal direction of the weight body is arranged in the X-axis direction or the Y-axis direction. To do.

  According to a ninth aspect of the present invention, there is provided a comb-like movable electrode integrally formed on a weight body provided on a substrate via an elastic member, and a comb tooth disposed to face the movable electrode. A capacitance-type acceleration sensor comprising a fixed electrode in the form of a movable electrode provided on one side of the weight body, and one first fixed electrode disposed so as to sandwich the movable electrode; One side electrode cell composed of the other second fixed electrode arranged so as to sandwich the movable electrode, a movable electrode provided on the other side of the weight body, and the movable electrode so as to sandwich the movable electrode An other-side electrode cell comprising one arranged first fixed electrode and the other second fixed electrode arranged so as to sandwich the movable electrode; the one-side electrode cell; and the other-side electrode An electrode cell structure is composed of cells. (Example 2)

  The invention described in claim 10 is the invention described in claim 9, characterized in that the movable electrode is arranged in a direction perpendicular to the longitudinal direction of the weight body.

  The invention according to claim 11 is the invention according to claim 9 or 10, wherein the one-side electrode cell and the other-side electrode cell are arranged symmetrically with respect to the longitudinal direction of the weight body. It is characterized by being.

  The invention according to claim 12 is the invention according to claim 9, 10 or 11, wherein the first fixed electrode and the second fixed electrode are arranged to face each other via the movable electrode. It is characterized by being.

  The invention according to claim 13 is the invention according to any one of claims 9 to 12, wherein a plurality of the electrode cell structures are continuously arranged along a longitudinal direction of the weight body. It is characterized by.

  The invention according to claim 14 is the invention according to any one of claims 9 to 13, characterized in that the longitudinal direction of the weight body is arranged on the X axis or the Y axis.

  According to the present invention, the capacitance of the movable electrode and the fixed electrode is provided with respect to the structure of the prior art so that the capacitance does not change when acceleration is applied in the direction perpendicular to the detection axis. As a result, the other axis sensitivity can be reduced compared to the conventional structure.

It is a block diagram for demonstrating the conventional electrostatic capacitance type acceleration sensor currently disclosed by patent document 2. FIG. 2A and 2B are diagrams for explaining the relationship of capacitance between a movable electrode and a fixed electrode in the capacitance type acceleration sensor shown in FIG. 1, wherein FIG. 'Line sectional view, (c) is a sectional view taken along line BB' of (a). BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram used as the premise of the capacitive acceleration sensor which concerns on this invention, (a) is a top view, (b) is the sectional view on the A-A 'line of (a). It is a signal detection block diagram in the capacitive acceleration sensor shown in FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram for demonstrating Example 1 of the capacitive acceleration sensor which concerns on this invention. 6A and 6B are diagrams for explaining the relationship of capacitance between the movable electrode and the fixed electrode in the first embodiment shown in FIG. 5, in which FIG. 5A is a top view, and FIG. FIG. 4C is a cross-sectional view taken along the line DD ′ in FIG. It is a block diagram for demonstrating the capacitive acceleration apparatus using the capacitive acceleration sensor which concerns on Example 1 of this invention. It is a block diagram for demonstrating Example 2 of the capacitive acceleration sensor which concerns on this invention.

Before describing each embodiment of the present invention, a configuration that is a premise of the capacitive acceleration sensor according to the present invention is described below.
FIGS. 3 (a) and 3 (b) are configuration diagrams on the premise of the capacitive acceleration sensor according to the present invention, FIG. 3 (a) is a top view, and FIG. 3 (b) is a diagram of FIG. 3 (a). It is AA 'line sectional drawing. In the figure, reference numeral 80 is a capacitive acceleration sensor, 81 is a substrate, 82 is a weight body (weight), 83 is an elastic member (spring), 84 is an anchor (support member), 85 is a movable electrode, and 86 is a fixed electrode. Is shown.

  The capacitive acceleration sensor 80 includes a displaceable weight body (weight) 82 disposed on the substrate 81 in a separated state, a movable electrode 85 provided on the weight body 82, and the movable electrode 85. A pair of fixed electrodes 86, 86 arranged to face each other so as to be sandwiched are provided, and a change in capacitance between the movable electrode and the fixed electrode is detected based on the displacement of the weight body 82.

  The movable electrode 85 is a plurality of thin plate-like comb-like movable electrodes, and the pair of fixed electrodes 86 and 86 arranged so as to sandwich the comb-like movable electrode is a plurality of thin-plate-like comb-teeth. This is a fixed electrode. The comb-shaped movable electrodes are provided on both sides in the Y-axis direction with respect to the X-axis direction, which is the displacement direction of the weight body 82, and the pair of comb-shaped fixed electrodes are comb-shaped. It arrange | positions facing a tooth-shaped movable electrode.

  The weight body 82 is attached to an anchor (post member) 84 provided on the substrate 81 via a beam member (elastic member) 83. One of the beam members 83 is coupled to the support member 84, and the other of the beam members 83 is coupled to the weight body 82. The beam member 83 is a spring member that is displaced with an elastic force against the horizontal displacement of the weight body 82.

  With such a configuration, it is possible to detect a change in capacitance that occurs between the movable electrode 85 and the fixed electrodes 86 and 86 when the weight body 82 is displaced.

  In FIG. 3, the case where the acceleration in the X-axis direction is detected has been described. However, when the acceleration in the Y-axis direction is detected, the capacitive acceleration sensor 80 shown in FIG. 3 is rotated by 90 degrees. Can be used to obtain an acceleration output in the Y-axis direction.

FIG. 4 is a block diagram of signal detection in the capacitive acceleration sensor shown in FIG. The capacitive acceleration sensor shown in FIG. 4 has the same structure as the capacitive acceleration sensor 80 described in FIG. For convenience of explanation, the fixed electrode 86 is a left fixed electrode 86L and a right fixed electrode 86R. The capacitance between the movable electrode 85 and the left fixed electrode 86L is C _L , and the capacitance between the movable electrode 85 and the right fixed electrode 86R is the same. It is set to C _R.

The drive circuit 91 is for passing the charge Q charged in C _L and C _R to the CV conversion circuits 92a and 92b, and is connected to the movable electrode 85. The CV conversion circuits 92a and 92b convert the change in Q into a voltage. X-axis direction acceleration is applied to, when the capacitance change occurs in the C _L and C _R, CV conversion circuit 92a, through 92b, fetches the capacitance difference C _L and C _R as the output of a differential amplifier 93. This output becomes the acceleration output in the X-axis direction.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 5 is a block diagram for explaining the first embodiment of the capacitive acceleration sensor according to the present invention. In FIG. 5, reference numeral 100 denotes the capacitive acceleration sensor according to the first embodiment. The type acceleration sensor 100 has a structure in which a plurality of electrode cell structures A including one-side electrode cells A1 and other-side electrode cells A2 are continuously arranged along the longitudinal direction of the weight body 101.

  The one-side electrode cell A1 has comb-like movable electrodes 101a and 101b integrally formed on a weight body 101 provided on a substrate 110 via an elastic member 103, and is opposed to the movable electrodes 101a and 101b. Comb-shaped fixed electrodes 111a, 111b, 112a, and 112b are provided.

  That is, the one-side electrode cell A1 includes a pair of movable electrodes 101a and 101b provided on one side of the weight body 101, and a pair of outer fixed electrodes 111a respectively disposed outside the pair of movable electrodes 101a and 101b. , 112a and a pair of inner fixed electrodes 111b, 112b disposed between the pair of movable electrodes 101a, 101b, respectively.

  The pair of movable electrodes 101a and 101b of the one-side electrode cell A1 includes a first movable electrode 101a and a second movable electrode 101b provided on one side of the weight body 101, and a pair of outer fixed electrodes. 111a and 112a are each composed of a first outer fixed electrode 111a and a second outer fixed electrode 112a arranged on the outer side of the pair of movable electrodes 101a and 101b, and the pair of inner fixed electrodes 111b and 112b is a pair. The second inner fixed electrode 112b and the first inner fixed electrode 111b are respectively arranged between the movable electrodes 101a and 101b.

  The other-side electrode cell A2 includes comb-shaped movable electrodes 102a and 102b integrally formed on a weight body 101 provided on the substrate 110 via an elastic member 103, and the movable electrodes 102a and 102b. And comb-like fixed electrodes 121a, 121b, 122a, 122b arranged opposite to each other.

  That is, the other-side electrode cell A2 includes a pair of movable electrodes 102a and 102b provided on the other side of the weight body 101, and a pair of outer fixed electrodes 121a respectively disposed outside the pair of movable electrodes 102a and 102b. , 122a and a pair of inner fixed electrodes 121b, 122b disposed between the pair of movable electrodes 102a, 102b, respectively.

  The pair of movable electrodes 102a and 102b of the other electrode cell A2 includes a first movable electrode 102a and a second movable electrode 102b provided on the other side of the weight body 101, and a pair of outer fixed electrodes. 121a and 122a are each composed of a first outer fixed electrode 121a and a second outer fixed electrode 122a arranged outside the pair of movable electrodes 102a and 102b, and the pair of inner fixed electrodes 121b and 122b is a pair. The second inner fixed electrode 122b and the first inner fixed electrode 121b are respectively arranged between the movable electrodes 102a and 102b.

  Further, the pair of movable electrodes 101 a and 101 b on one side and the pair of movable electrodes 102 a and 102 b on the other side are arranged in a direction perpendicular to the longitudinal direction of the weight body 101. Further, the one-side electrode cell A1 and the other-side electrode cell A2 are arranged symmetrically with respect to the longitudinal direction of the weight body 101.

  In addition, the first outer fixed electrode 111a and the first inner fixed electrode 111b on one side are connected, and the second outer fixed electrode 112a and the second inner fixed electrode 112b are connected on the other side. The first outer fixed electrode 121a and the first inner fixed electrode 121b are connected to each other, and the second outer fixed electrode 122a and the second inner fixed electrode 122b are connected to each other.

  Further, the first outer fixed electrode 111a and the second inner fixed electrode 112b on one side are arranged to face each other via the first movable electrode 101a, and the second outer fixed electrode 112a and the first inner fixed electrode are disposed. 111b is disposed opposite to the second movable electrode 101b.

  Further, the first outer fixed electrode 121a and the second inner fixed electrode 122b on the other side are arranged to face each other via the first movable electrode 102a, and the second outer fixed electrode 122a and the first inner fixed electrode are disposed. 121b is disposed opposite to the second movable electrode 102b.

  In the above-described first embodiment, the case where the longitudinal direction of the weight body is arranged in the X-axis direction in order to detect the acceleration in the X-axis direction has been described. Obviously, if it is arranged in the axial direction, acceleration in the Y-axis direction can be detected.

  6A to 6C are diagrams for explaining the relationship of capacitance between the movable electrode and the fixed electrode in the first embodiment shown in FIG. 5, and FIG. 6A is a top view, FIG. 6 (b) is a cross-sectional view taken along the line CC 'in FIG. 6 (a), and FIG. 6 (c) is a cross-sectional view taken along the line DD' in FIG. 6 (a).

In the figure, symbols C _L1 , C _L2 , C _L5 , and C _L6 are capacitances formed between the movable electrode 101a and the movable electrode 102a and the outer fixed electrode 111a and the outer fixed electrode 121a, C _L3 , C _L4 , and C _L7. , _{C L8} is the capacitance formed between the movable electrode 101b and the movable electrode 102b and the inner fixed electrode 111b and the inner fixed electrode _{121b, C R1, C R2,} C R5, C R6 is movable electrode 101a and the movable electrode Capacitors C _R3 , C _R4 , C _R7 , and C _R8 formed between 102a and the inner fixed electrode 112b and the inner fixed electrode 122b are the movable electrode 101b, the movable electrode 102b, the outer fixed electrode 112a, and the outer fixed electrode 122a. The capacitance formed between the two is shown.

When acceleration is not applied (G = 0), (C _L1 + C _L2 +... + C _L8 ) − (C _R1 + C _R2 +... + C _R8 ) = 0, and matching with the offset can be obtained. When acceleration is applied in the direction perpendicular to the detection axis (G ≠ 0), the detection axis is not detected in C _L1 , C _L2 , C _L3 , C _L4 , C _R1 , C _R2 , C _R3 , C _R4 . It is insensitive to vertical acceleration, and C _L5 = C _R7 , C _R5 = C _L7 , C _L6 = C _R8 , C _R6 = C _L8 (C _L5 + C _L6 +... + C _L8 ) − (C _R5 + C _R6 +... + C _R8 ) = 0, which indicates that this configuration is effective for the sensitivity of other axes.

  As described above, in the capacitive acceleration sensor according to the first embodiment, by optimizing the arrangement of the fixed electrode, the capacitance of the fixed electrode facing the movable electrode is accelerated in the direction perpendicular to the detection axis. In this case, an electrode arrangement pattern structure that does not cause capacitance change can be provided. In this structure, it is possible to provide a capacitive acceleration sensor in which the other-axis sensitivity is reduced and a capacitive acceleration device using the same.

  FIG. 7 is a block diagram for explaining a capacitive acceleration device using the capacitive acceleration sensor according to the first embodiment of the present invention. The capacitive acceleration sensor shown in FIG. 7 has the same structure as the capacitive acceleration sensor 100 described in FIG.

The drive circuit 91 passes the charge Q charged to C _L1 , C _L2 , C _L5 , C _L6 and C _L3 , C _L4 , C _L7 , C _L8 to the CV conversion circuit 92a, and C C to the CV conversion circuit 92b. _R1 , C _R2 , C _R5 , C _R6, and C _R3 , C _R4 , C _R7 , C _R8 are passed to charge Q and are connected to the movable electrode 101. The CV conversion circuits 92a and 92b convert the change in Q into a voltage. Acceleration is applied in the X-axis direction, and C _L1 , C _L2 , C _L5 , C _L6 and C _L3 , C _L4 , C _L7 , C _L8 , C _R1 , C _R2 , C _R5 , C _R6 and C _R3 , C _R4, when _{a C R7,} capacitance change in _{C R8} occurs, CV conversion circuit 92a, through _92b, the _{C L1, C L2, C L5} , C L6 and _{C L3, C L4, C L7} , C L8, C R1 , C _R2 , C _R5 , C _R6 and C _R3 , C _R4 , C _R7 , C _R8 are extracted as outputs by the differential amplifier 93. This output becomes the acceleration output in the X-axis direction.

  As described above, it is possible to realize the capacitive acceleration device that detects the acceleration from the output signal of the sensor through the signal processing circuit by using the capacitive acceleration sensor in the first embodiment.

  FIG. 8 is a configuration diagram for explaining a second embodiment of the capacitive acceleration sensor according to the present invention. In FIG. 8, reference numeral 200 denotes a capacitive acceleration sensor according to the second embodiment. The type acceleration sensor 200 has a structure in which a plurality of electrode cell structures B each composed of one side electrode cell B1 and another side electrode cell B2 are continuously arranged along the longitudinal direction of the weight body 201.

  The one-side electrode cell B1 includes a comb-like movable electrode 201a integrally formed on a weight body 201 provided on a substrate 210 via an elastic member (not shown), and is opposed to the movable electrode 201a. Comb-shaped fixed electrodes 211 and 212 are provided.

  That is, the one-side electrode cell B1 includes a movable electrode 201a provided on one side of the weight body 201, one first fixed electrode (L) 211 disposed so as to sandwich the movable electrode 201a, and a movable electrode 201a. It is comprised with the other 2nd fixed electrode (R) 212 arrange | positioned so that the electrode 201a may be pinched | interposed.

  The other electrode cell B2 includes a comb-like movable electrode 202a integrally formed on a weight body 201 provided on a substrate 210 via an elastic member (not shown), and the movable electrode 202a. And comb-like fixed electrodes 221 and 222 arranged opposite to each other.

  That is, the other-side electrode cell B2 is movable with the movable electrode 202a provided on the other side of the weight body 201 and one first fixed electrode (L) 221 disposed so as to sandwich the movable electrode 202a. The other fixed electrode (R) 222 is disposed so as to sandwich the electrode 202a.

  The movable electrode 201a on one side and the movable electrode 202a on the other side are arranged in a direction perpendicular to the longitudinal direction of the weight body 201, and the one-side electrode cell B1 and the other-side electrode cell B2 are It is arranged symmetrically with respect to the longitudinal direction of 201.

  Further, the first fixed electrode 211 and the second fixed electrode 212 on one side are arranged to face each other via the movable electrode 201a, and the first fixed electrode 221 and the second fixed electrode 222 on the other side are Oppositely arranged via the movable electrode 202a.

  In the above-described second embodiment, the case where the longitudinal direction of the weight body is arranged in the X-axis direction in order to detect the acceleration in the X-axis direction has been described. Obviously, if it is arranged in the axial direction, acceleration in the Y-axis direction can be detected.

  Using the capacitive acceleration sensor according to the second embodiment described above, it is possible to realize a capacitive acceleration device that detects acceleration from the output signal of the sensor via a signal processing circuit.

  As described above, by optimizing the arrangement of the fixed electrodes in the capacitive acceleration sensor of the second embodiment, as described above, the arrangement of the fixed electrodes in the capacitive acceleration sensor of the first embodiment is changed. By optimizing, it is possible to provide an electrode arrangement pattern structure in which the capacitance of the fixed electrode facing the movable electrode does not change when the acceleration is applied in the direction perpendicular to the detection axis. In this structure, it is possible to provide a capacitive acceleration sensor in which the other-axis sensitivity is reduced and a capacitive acceleration device using the same.

22 Silicon substrate 24 Polysilicon beams 26A to 26D Anchors 28 and 32 Narrow foot 34 Transverse center members 36 and 38 Beam fingers 42 and 44 Stationary members 62A to 62D Cell 80 Capacitive acceleration sensor 81 Substrate 82 Weight (weight)
83 Elastic member (spring)
84 Anchor (support member)
85 Movable electrode 86 Fixed electrode 91 Drive circuit 92a, 92b CV conversion circuit 93 Differential amplifier 100, 200 Capacitive acceleration sensor 101, 201 Weight body 103 Elastic member 110, 210 Substrate 101a, 101b, 201a Movable on one side Electrodes 111a, 111b, 112a, 112b, 211, 212 One side fixed electrodes 102a, 102b, 202a The other side movable electrodes 121a, 121b, 122a, 122b, 221, 222 The other side fixed electrodes A1, B1 One side electrode cell A2, B2 Other electrode cell A, B Electrode cell structure

Claims (14)

Capacitance provided with a comb-like movable electrode integrally formed on a weight body provided via an elastic member on a substrate, and a comb-like fixed electrode arranged opposite to the movable electrode Type acceleration sensor
A pair of movable electrodes provided on one side of the weight body, a pair of outer fixed electrodes respectively disposed outside the pair of movable electrodes, and a pair of inner sides disposed between the pair of movable electrodes A one-side electrode cell composed of a fixed electrode;
A pair of movable electrodes provided on the other side of the weight body, a pair of outer fixed electrodes respectively disposed outside the pair of movable electrodes, and a pair of inner sides disposed between the pair of movable electrodes. The other electrode cell composed of a fixed electrode and
A capacitive acceleration sensor comprising an electrode cell structure composed of the one-side electrode cell and the other-side electrode cell.   The capacitive acceleration sensor according to claim 1, wherein the pair of movable electrodes are arranged in a direction perpendicular to a longitudinal direction of the weight body.   3. The capacitive acceleration sensor according to claim 1, wherein the one-side electrode cell and the other-side electrode cell are arranged symmetrically with respect to a longitudinal direction of the weight body. . The pair of movable electrodes of the one-side electrode cell includes a first movable electrode and a second movable electrode provided on one side of the weight body, and the pair of outer fixed electrodes is the pair of outer fixed electrodes. A first inner fixed electrode and a second outer fixed electrode respectively disposed outside the movable electrode, and the pair of inner fixed electrodes are disposed between the pair of movable electrodes, respectively. An electrode and a first inner fixed electrode;
The pair of movable electrodes of the other electrode cell includes a first movable electrode and a second movable electrode provided on the other side of the weight body, and the pair of outer fixed electrodes is the pair of outer fixed electrodes. A first inner fixed electrode and a second outer fixed electrode respectively disposed outside the movable electrode, and the pair of inner fixed electrodes are disposed between the pair of movable electrodes, respectively. 4. The capacitive acceleration sensor according to claim 1, 2, or 3, comprising an electrode and a first inner fixed electrode. The first outer fixed electrode and the first inner fixed electrode on the one side are connected, and the second outer fixed electrode and the second inner fixed electrode are connected,
The first outer fixed electrode and the first inner fixed electrode on the other side are connected, and the second outer fixed electrode and the second inner fixed electrode are connected. The capacitive acceleration sensor according to claim 4, wherein:   The first outer fixed electrode and the second inner fixed electrode are arranged to face each other via the first movable electrode, and the second outer fixed electrode and the first inner fixed electrode are 6. The capacitive acceleration sensor according to claim 4, wherein the acceleration sensor is disposed so as to face the second movable electrode.   7. The capacitive acceleration sensor according to claim 1, wherein a plurality of the electrode cell structures are continuously arranged along a longitudinal direction of the weight body.   The capacitive acceleration sensor according to any one of claims 1 to 7, wherein a longitudinal direction of the weight body is arranged in an X-axis direction or a Y-axis direction. Capacitance provided with a comb-like movable electrode integrally formed on a weight body provided via an elastic member on a substrate, and a comb-like fixed electrode arranged opposite to the movable electrode Type acceleration sensor
A movable electrode provided on one side of the weight body, one first fixed electrode arranged to sandwich the movable electrode, and the other second fixed electrode arranged to sandwich the movable electrode A one-side electrode cell composed of electrodes,
A movable electrode provided on the other side of the weight body, one first fixed electrode disposed so as to sandwich the movable electrode, and the other second fixed member disposed so as to sandwich the movable electrode. The other electrode cell composed of electrodes,
A capacitive acceleration sensor comprising an electrode cell structure composed of the one-side electrode cell and the other-side electrode cell.   The capacitive acceleration sensor according to claim 9, wherein the movable electrode is arranged in a direction perpendicular to a longitudinal direction of the weight body.   The capacitive acceleration sensor according to claim 9 or 10, wherein the one-side electrode cell and the other-side electrode cell are arranged axially symmetrically with respect to a longitudinal direction of the weight body. .   12. The capacitive acceleration sensor according to claim 9, 10 or 11, wherein the first fixed electrode and the second fixed electrode are arranged to face each other with the movable electrode interposed therebetween.   The capacitive acceleration sensor according to any one of claims 9 to 12, wherein a plurality of the electrode cell structures are continuously arranged along a longitudinal direction of the weight body.   The capacitive acceleration sensor according to claim 9, wherein a longitudinal direction of the weight body is arranged on an X axis or a Y axis.

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