WO2008026331A1

WO2008026331A1 - Capacitive acceleration sensor

Info

Publication number: WO2008026331A1
Application number: PCT/JP2007/052231
Authority: WO
Inventors: Kosuke Uga; Manabu Tamura; Chisato Iwasaki; Makoto Sasaki
Original assignee: Alps Electric Co., Ltd.
Priority date: 2006-09-01
Filing date: 2007-02-08
Publication date: 2008-03-06

Abstract

When a relatively low G is applied, weight portions (11b1, 11b2) at the large weight portion of a movable electrode (11) oscillate downward with a first beam portion (11d) as a fulcrum, and weight portions (11b3, 11b4) at the large weight portion oscillate upward with the first beam portion (11d) as a fulcrum. From a variation in capacitance at that time, measurement acceleration when a relatively low G is applied can be calculated. When a relatively high G is applied, the weight portions (11b1, 11b2) at the large weight portion of the movable electrode (11) oscillate downward with the first beam portion (11d) as a fulcrum to abut against a stopper layer (14) on a fixed electrode (12a), and then a small weight portion (11c) oscillates with a second beam portion (11e) as a fulcrum. From a variation in capacitance at that time, measurement acceleration when a relatively high G is applied can be calculated.

Description

Specification

Capacitance type acceleration sensor

Technical field

The present invention relates to a capacitance type acceleration sensor that detects acceleration using capacitance.

Background art

[0002] In view of the need for downsizing and higher functionality of devices using an acceleration sensor, an acceleration sensor capable of measuring acceleration in a plurality of ranges with a single sensor is desired. For example, Japanese Patent Laid-Open No. 3-112168 (Patent Document 1) discloses a piezo-type acceleration sensor that can measure acceleration in two ranges. .

Patent Document 1: JP-A-3-112168

Disclosure of the invention

Problems to be solved by the invention

However, the piezo-type acceleration sensor disclosed in the above-mentioned patent document has a problem that the accuracy of acceleration measurement is poor because the temperature characteristics are poor. In this case, in order to accurately measure acceleration regardless of temperature changes, it is necessary to perform temperature compensation using a temperature sensor or the like.

[0004] An object of the present invention is to provide a capacitive acceleration sensor that can accurately measure acceleration regardless of temperature changes and can measure in a plurality of ranges. Means for solving the problem

[0005] The capacitive acceleration sensor of the present invention is disposed so as to face a first substrate having a fixed electrode and the fixed electrode, and is capable of forming a capacitance to be measured between the fixed electrode. A capacitance-type acceleration sensor that measures acceleration by changing the capacitance, and the movable electrode starts to swing when a relatively low G is applied. And a small weight portion that starts swinging when a relatively high G is applied, and the small weight portion constitutes a part of the weight of the large weight portion, and the large weight portion When swinging Are characterized by rocking together.

[0006] According to this configuration, the large weight portion and the small weight portion are provided, and when the relatively low G is added, the large weight portion swings, and when the relatively high G is added, the small weight Since the part swings, it is possible to measure acceleration in multiple ranges.

[0007] In the capacitive acceleration sensor of the present invention, the fixed electrode includes a first fixed electrode for a large weight portion and a second fixed electrode for a small weight portion, and the first fixed electrode The electrode preferably has a strobe layer that prevents electrical contact with the mass portion when a relatively high G is applied.

[0008] According to this configuration, since the fixed electrode is divided into a large weight portion (for low G) and a small weight portion (for high G), more accurate acceleration can be measured over a wide range. In addition, by using the stopper layer, it is possible to prevent an excessive force from acting on the mass portion and damage it, and to prevent electrical contact.

In the capacitive acceleration sensor of the present invention, it is preferable that the first fixed electrode is divided so as to be symmetric with respect to each of two orthogonal axes on the electrode surface. According to this configuration, when the mass portion is displaced, accelerations in the two orthogonal (X, Y) and Z-axis directions on the electrode surface can be measured.

In the capacitive acceleration sensor of the present invention, it is preferable that the second fixed electrode is divided so as to be symmetric with respect to each of the two orthogonal axes. According to this configuration, relatively high acceleration is applied, and acceleration in the X, Υ, and Z directions can be measured even when the spindle is displaced.

[0011] In the capacitive acceleration sensor of the present invention, the movable electrode includes a frame, a first beam portion connecting the frame and the large weight portion or the small weight portion, and the large weight. It is preferable that a second beam portion connecting the portion and the small weight portion is included. According to this configuration, the structure having the first beam portion and the second beam portion can be made workable, reliable, and downsized, and is excellent in design ease and cost reduction.

Brief Description of Drawings

FIG. 1 is a plan view showing a movable electrode of a capacitive acceleration sensor according to Embodiment 1 of the present invention. FIG. 2 is a plan view showing fixed electrodes of the capacitive acceleration sensor according to the first embodiment of the present invention.

FIG. 3 is a side view showing the capacitive acceleration sensor according to the first embodiment of the present invention.

[FIG. 4] (a) and (b) are diagrams for explaining the operation of the capacitive acceleration sensor according to the first embodiment of the present invention.

FIG. 5 is a side view showing a capacitive acceleration sensor according to a second embodiment of the present invention.

FIG. 6 is a plan view showing fixed electrodes of the capacitive acceleration sensor according to the second embodiment of the present invention.

FIG. 7 is a plan view showing another example of the movable electrode of the capacitive acceleration sensor according to the embodiment of the present invention.

FIG. 8 is a plan view showing another example of the movable electrode of the capacitive acceleration sensor according to the embodiment of the present invention.

FIG. 9 is a side view showing another example of the stagger layer of the capacitive acceleration sensor according to the embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

(Embodiment 1)

FIG. 1 is a plan view showing movable electrodes of the capacitive acceleration sensor according to the first embodiment of the present invention. The movable electrode 11 includes a frame 11a that is a second substrate, a mass part provided on the frame 11a, and a small mass part 11c provided on the mass part. In FIG. 1, the movable electrode 11 includes a first beam portion l id that connects the frame body 11a and the large weight portion, and a second beam portion l ie that connects the large weight portion and the small weight portion 11c. including.

[0014] The mass part is located in the frame 11a, and is connected to a plurality of (here, four) 鍾咅 llb 1, lib 2, lib 3, lib, and 鍾咅

4 llb 1, lib 2, lib 3, lib

Four

It is composed of a small weight portion l ie connected by two beam portions l ie. That is, the small weight portion 11c also serves as the large weight portion. The mass portion swings when a relatively low G is applied. The small spindle 11c swings when a relatively high G is applied.

FIG. 2 shows a fixed electrode of the capacitive acceleration sensor according to the first embodiment of the present invention. It is a top view. The fixed electrode 12 is disposed at a position facing the movable electrode 11. The fixed electrode 12 is formed on the first substrate, the fixed electrode 12e is disposed at the center, and the fixed electrodes 12a, 12b, 12c, and 12 (one self-positioned around the fixed electrode 12e). 12a, 12b, 12c, 12d are mainly used when measuring acceleration with relatively low G, and the inner fixed electrode 12e is mainly with relatively high G. In other words, the acceleration with the relatively low G added is mainly 鍾咅 llb, lib, lib, lib of the movable electrode 11 and the fixed electrodes 12a, 12b, 12c, 12d and

1 2 3 4

The acceleration in the state where G, which is relatively high, is mainly applied is the capacitance between the small weight part 11c of the movable electrode 11 and the fixed electrode 12e. Measured based on changes in.

Specifically, in the arrangement of the fixed electrodes shown in FIG. 2, the acceleration in the X-axis direction mainly with a relatively low G added is caused by the weights l ib and l ib and the fixed electrodes 12a Capacitance between

1 2

Measurement using the change in capacitance and the change in capacitance between the weight l ib and l ib and the fixed electrode 12b.

3 4

The acceleration in the Y-axis direction with the relatively low G added is the weights l ib, l ib

1 4 Capacitance change between the fixed electrode 12c and static electricity between the weights l ib, l ib and the fixed electrode 12d

twenty three

Measured using capacitance change.

FIG. 3 is a side view showing the capacitive acceleration sensor according to the first embodiment of the present invention. The capacitive acceleration sensor 1 is mainly composed of a first substrate 13 having a fixed electrode 12, a second substrate having a movable electrode 11, and the like. The second substrate has a space 1 If for accommodating at least the fixed electrode 12 and a space 1 lg for accommodating at least the large weight portion 1 lb and the small weight portion 1 lc. The second substrate is bonded onto the first substrate 13 so that the fixed electrode 12 on the first substrate 13 and the movable electrode 11 on the second substrate face each other. A third substrate 15 is bonded onto the second substrate. As a result, as shown in FIG. 3, the second substrate having the movable electrode 11 is sandwiched between the first substrate 13 and the third substrate 15. Then, the movable electrode 11 and the fixed electrode 12 are arranged in the cavity 16 constituted by these substrates. In addition, a capacitance to be measured is formed between the movable electrode 11 and the fixed electrode 12.

[0018] Assuming that the weight portion is a rigid body, the shape, length, and thickness of the first beam portion l id and the second beam portion l ie are set based on the maximum deflection of the beam portion. The maximum deflection Y of the beam is as follows: You can ask for it.

Y = WL ³ / (192-EI) Formula (1)

W = F = m-a Formula (2)

I = DH ^3/12 Equation (3)

From Equation 1 to Equation 3,

Y = (E / 16) · {L ³ / (DH ³ )} -ma

Where W: Load applied, F: Applied force, a: Acceleration, L: Beam length, E: Beam Young's modulus, I: Cross section secondary moment, D: Beam width, H: The thickness of the beam.

[0019] It is desirable to set the volume of the weight portion in consideration of such maximum deflection of the beam portion. For example, the volume ratio between the weight l ib and the small weight portion 11c is preferably about 5: 1.

[0020] As described above, the movable electrode 11 includes a large rod including 鍾咅 l ib, l ib, l ib, and l ib, and / J ヽ

1 2 3 4

It has a weight portion l ie, a first beam portion l id, and a second beam portion l ie. In such a movable electrode 11, when the relatively low G is strong, the mass portion including the small mass portion 11c swings with the first beam portion id as a fulcrum, and the relatively high G In the state where is added, the small weight portion 11c swings around the second beam portion l ie as a fulcrum. As the large spindle or small spindle swings and displaces in this way, the distance to the fixed electrode 12 changes, and the change in capacitance due to the change in the distance can be detected. The acceleration can be measured by the capacitance change.

[0021] On the fixed electrodes 12a, 12b, 12c, and 12d for the mass portion of the fixed electrode 12, a stagger layer that prevents electrical contact with the mass portion when relatively high G is applied. 14 is formed. In a state where a certain amount of G is added, the weight part l ib of the large weight part is greatly swung to contact the stopper layer 14. As a result, even if more G is added, the mass portion does not swing. At this time, the stopper layer 14 prevents the weight l ib that is a movable electrode and the fixed electrodes 12a, 12b, 12c, and 12d from being in electrical contact. As a material for the stopper layer 14, an insulating material is used. Further, the thickness of the stagger layer 14 is not particularly limited as long as the function is exhibited.

[0022] The capacitive acceleration sensor having such a configuration is manufactured, for example, as follows. First, the fixed electrodes 12a, 12b, 12c, 12d, and 12e are formed on the first substrate 13, and the stopper layer 14 is formed on the fixed electrodes 12a, 12b, 12c, and 12d. Formation of fixed electrode 12 and stopper layer 14 For example, it is performed by photolithography and etching. Next, both main surfaces of the second substrate are processed by etching or the like to move the movable electrode 11 (large weight portion, small weight portion l lc, first beam portion l id and second beam portion l ie) and space l lf, l Form lg. Then, one main surface of the second substrate is bonded onto the first substrate 13 so that the fixed electrode 12 is accommodated in the space l lf, and the third substrate 15 is formed on the other main surface of the second substrate. Join. It should be noted that the same effect can be obtained even if the strobe is provided on the movable electrode side.

In such a capacitance type acceleration sensor, in order to improve the airtightness of the cavity 16, the first substrate 13 and the third substrate 15 are made of a glass substrate, and the second substrate is a silicon substrate. It is preferable to comprise. As a result, anodic bonding can be performed between the glass substrate and the silicon substrate, and the adhesion of the interface between the glass substrate and the silicon substrate can be increased, and the air tightness of the cavity 16 can be increased. By increasing the airtightness in the cavity 16 in this way, the weight portion in the cavity 16 is not subjected to the viscous resistance of air and exhibits high sensitivity to acceleration. In such a configuration, it is possible to realize a structure in which a conductive member is embedded in a glass substrate and the fixed electrode and the movable electrode are drawn out through the conductive member. The lead electrode is one of the main substrates of the glass substrate. It is possible to make a surface-mount structure that is arranged side by side on the surface.

Next, a case where acceleration is measured by the capacitance acceleration sensor having the above configuration will be described.

First, when a relatively low G (for example, 2G) is added to the + X side shown in FIG. 2, as shown in FIG. 4 (a), the weight parts l ib and l ib of the large weight part of the movable electrode 11 are 1st beam part l id downward

1 2

Rocks. As a result, the weight parts l ib, l ib are displaced, and the weight parts l ib, l ib and the fixed electrode 1

1 2 1 2

The distance between 2a is shortened. On the other hand, the weight parts l ib and l ib of the large weight part of the movable electrode 11 are the first beam.

3 4 Part l Swing upward with the id as a fulcrum. As a result, the weight parts l ib and l ib are displaced, and the weight part l ib

3 4

, L ib and the distance between fixed electrode 12b become longer. At this time, the weight parts l ib and l ib and the fixed

3 4 1 2 Capacitance C between the poles 12a and capacitance C between the weights l ib and l ib and the fixed electrode 12b

The difference between 1 3 4 2 (C – C) is the measurement capacity corresponding to the acceleration in the X-axis direction. From this measured capacity,

1 2

The X-axis direction component of the measured acceleration when G, which is relatively low, is strong can be calculated. In this case, since the measured capacity is obtained from the difference in capacitance, the temperature characteristics are canceled. It is possible to

Similarly, when a relatively low G (for example, 2G) is added to the X side as shown in FIG. 2, the weight parts lib and lib of the large weight part of the movable electrode 11 support the first beam part lid. Swings downward. to this

3 4

Therefore, the weight parts lib and lib are displaced, and the distance between the weight parts lib and lib and the fixed electrode 12b is

3 4 3 4

Shorter. On the other hand, the weight parts lib and lib of the large weight part of the movable electrode 11 are located above the first beam part lid as a fulcrum.

1 2

Swings in the direction. As a result, the weight parts lib and lib are displaced, and the weight parts lib and lib and the fixed electrode

1 2 1 2

The distance to 12a becomes longer. At this time, the static between the weight parts lib, lib and the fixed electrode 12b

3 4

The difference between the capacitance C and the capacitance C between the weight parts lib and lib and the fixed electrode 12a (C C) is

2 1 2 1 2 2

The measurement capacity corresponds to the acceleration in the X-axis direction. From this measured capacity, the X-axis direction component of the measured acceleration when a relatively low G is added can be calculated. In this case, since the measured capacity is obtained from the difference in electrostatic capacity, it is possible to cancel the temperature characteristics.

Similarly, when a relatively low G (for example, 2G) is added to the + Y side shown in FIG. 2, the weight parts lib and lib of the large weight part of the movable electrode 11 support the first beam part lid. Swings downward. to this

14

Therefore, the weight parts lib and lib are displaced, and the distance between the weight parts lib and lib and the fixed electrode 12c is

1 4 1 4

twenty three

2 3 2 3

The distance between 12d becomes longer. At this time, the static between the weight parts lib, lib and the fixed electrode 12c

14

The difference between the capacitance C and the capacitance C between the weight parts lib, lib and the fixed electrode 12d (C C) is

3 2 3 4 3 4

The measurement capacity corresponds to the acceleration in the Y-axis direction. From this measured capacity, the Y-axis direction component of the measured acceleration when a relatively low G is added can be calculated. In this case, since the measured capacity is obtained from the difference in electrostatic capacity, it is possible to cancel the temperature characteristics.

Similarly, when a relatively low G (for example, 2G) is added to the Y side shown in FIG. 2, the weight parts lib and lib of the large weight part of the movable electrode 11 use the first beam part lid as a fulcrum. Swings downward. to this

twenty three

Therefore, the weight parts lib and lib are displaced, and the distance between the weight parts lib and lib and the fixed electrode 12d is

2 3 2 3

14

Swings in the direction. As a result, the weight parts lib and lib are displaced, and the weight parts lib and lib and the fixed electrode The distance to 12c is longer. At this time, the static force between the weights l ib and l ib and the fixed electrode 12d

twenty three

The difference between the capacitance C and the capacitance C between the weight parts l ib and l ib and the fixed electrode 12c (C C) is

4 1 4 3 4 3

[0028] When a relatively low G (for example, 2G) is added in the Z-axis direction, the weights l ib, l ib and

1 2 Capacitance C between the fixed electrode 12a and electrostatic capacity between the weights l ib and l ib and the fixed electrode 12b

1 3 4

Capacitance C and the capacitance C between the weight parts l ib and l ib and the fixed electrode 12c and the weight parts l ib and l ib

2 1 4 3 2 3 and the capacitance C between the fixed electrode 12d and the measurement capacitance corresponding to the acceleration in the Z-axis direction.

Four

It becomes quantity. This measured capacitive force can also calculate the z-axis direction component of the measured acceleration. In this case, it is possible to cancel the temperature characteristics by providing a reference capacitance for detection in the Z-axis direction and subtracting the above-mentioned sum of the capacitance reference capacitance.

[0029] When a relatively high G (for example, 60G) is added, as shown in FIG. 4 (b), first, the weight parts l ib and l ib of the large weight part of the movable electrode 11 are the first beam parts. l Swing downward with id as a fulcrum

1 2

It contacts the stopper layer 14 on the constant electrode 12a. As a result, the weight part l ib and l ib force S of the large weight part

1 2 Can no longer swing. Thereafter, the small weight portion 11c swings around the second beam portion ie. As a result, the small weight part 11c is displaced, and the distance between the small weight part 11c and the fixed electrode 12e is shortened. At this time, the capacitance C between the small weight portion 11c and the fixed electrode 12e becomes a measurement capacitance corresponding to the acceleration in the Z-axis direction. From this measured capacity, the Z-axis direction component of the measured acceleration when a relatively high G is applied can be calculated.

[0030] As described above, since the capacitance type acceleration sensor according to the present embodiment obtains the measurement capacitance from the difference in capacitance, it can accurately measure the acceleration regardless of the temperature change. . In addition, a large weight part and a small weight part are provided so that the large weight part swings when a relatively low G is added and the small weight part swings when a relatively high G is added. Therefore, it is possible to measure in multiple ranges.

[0031] (Embodiment 2) In the present embodiment, a capacitive acceleration sensor capable of measuring acceleration components in three axis directions even when a relatively high G is applied will be described.

FIG. 5 is a side view showing the capacitive acceleration sensor according to the second embodiment of the present invention. In FIG. 5, the same parts as those in FIG. 3 are denoted by the same reference numerals as those in FIG. As shown in FIG. 5, in the capacitive acceleration sensor according to the present embodiment, the fixed electrode 12e with respect to the small weight portion 11c of the fixed electrode 12 is divided. FIG. 6 is a plan view showing a fixed electrode of the capacitive acceleration sensor according to the second embodiment of the present invention. As shown in FIG. 6, the fixed electrode 12e for the small weight portion 11c has a plurality (four in this case) of fixed electrodes 12e, 12e, 12e, 12e. These fixed electrodes 12e, 12e,

1 2 3 4 1 2

12e and 12e are arranged so as to face the small weight portion 11c of the movable electrode 11, as shown in FIG.

3 4

It is.

The case where a relatively low G (for example, 2G) is added is the same as in the first embodiment. When a relatively high G (for example, 60G) is added to the + X side shown in Fig. 6, the weights l ib and l ib of the mass part of the movable electrode 11 swing downward with the first beam part l id as a fulcrum. Moving and fixed electrode 12a

1 2

Then, the small weight portion 11c swings around the second beam portion l ie as a fulcrum.

At this time, the + X side (right side of the drawing) of the small weight portion 11c of the movable electrode 11 swings downward with the second beam portion lie as a fulcrum. As a result, the + X side of the small weight part 11c is displaced, and the distance between the + X side of the small weight part 11c and the fixed electrode 12e is shortened. On the other hand, the small weight portion 11c of the movable electrode 11

1

The X side (left side of the page) swings upward with the second beam part id as a fulcrum. As a result, the −X side of the small weight portion 11c is displaced, and the distance between the −X side of the small weight portion 11c and the fixed electrode 12e is increased.

Three

Become. At this time, the electrostatic capacitance C between the + X side of the small weight part 11c and the fixed electrode 12e and the small weight

1 1 Part 11c — The difference in capacitance C between the X side and the fixed electrode 12e (C — C)

3 2 1 2

The measured capacity corresponds to the speed. From this measured capacity, the X-axis direction component of the measured acceleration when a relatively high G is added can be calculated. In this case, since the measured capacity is obtained from the difference in electrostatic capacity, it is possible to cancel the temperature characteristic.

[0035] Similarly, when a relatively high G (for example, 60G) is added to the X side as shown in Fig. 6, it is movable. The X side of the small weight portion l ie of the electrode 11 swings downward with the second beam portion l ie as a fulcrum. As a result, the —X side of the small weight portion 11c is displaced, and the distance between the —X side of the small weight portion 11c and the fixed electrode 12e.

Three

Release is shortened. On the other hand, the + X side of the small weight l ie of the movable electrode 11 swings upward with the second beam l id as a fulcrum. As a result, the + X side of the small weight part 11c is displaced, and the distance between the + X side of the small weight part 11c and the fixed electrode 12e is increased. At this time, one X side of the small weight portion 11c and the fixed electrode 12

1

Capacitance C between e and the capacitance C between the + X side of the small spindle 11c and the fixed electrode 12e

The difference between 3 2 1 1 (C – C) is the measurement capacity corresponding to the acceleration in the X-axis direction. From this measured capacity,

twenty one

The X-axis direction component of the measured acceleration when a relatively high G is added can be calculated. In this case, since the measured capacitance is obtained from the difference in capacitance, it is possible to cancel the temperature characteristic.

Similarly, when a relatively high G (for example, 60G) is added to the + Y side shown in FIG. 6, the + Y side of the small weight portion 11c of the movable electrode 11 is lowered with the second beam portion lie as a fulcrum. Rocks. As a result, the + Y side of the small weight part 11c is displaced, and the distance between the + Y side of the small weight part 11c and the fixed electrode 12e.

Four

Release is shortened. On the other hand, the −Y side of the small weight portion l ie of the movable electrode 11 swings upward with the second beam portion l id as a fulcrum. As a result, the Y side of the small weight part 11c is displaced, and the distance between the −Y side of the small weight part 11c and the fixed electrode 12e is increased. At this time, the + Y side of the small weight portion 11c and the fixed electrode 12

2

Capacitance C between e and the capacitance C between the Y side of the small spindle 11c and the fixed electrode 12e

The difference between 4 3 2 4 (C – C) is the measurement capacity corresponding to the acceleration in the Y-axis direction. From this measured capacity,

3 4

The Y-axis direction component of the measured acceleration when a relatively high G is added can be calculated. In this case, since the measured capacitance is obtained from the difference in capacitance, it is possible to cancel the temperature characteristic.

[0037] Similarly, when a relatively high G (for example, 60G) is added to the Y side shown in FIG. 6, the Y side of the small weight portion 11c of the movable electrode 11 faces downward with the second beam portion lie as a fulcrum. Swing. As a result, the Y side of the small weight part 11c is displaced, and the distance between the −Y side of the small weight part 11c and the fixed electrode 12e.

2

Release is shortened. On the other hand, the + Y side of the small weight portion l ie of the movable electrode 11 swings upward with the second beam portion l id as a fulcrum. As a result, the + Y side of the small weight part 11c is displaced, and the distance between the + Y side of the small weight part 11c and the fixed electrode 12e is increased. At this time, one Y side of the small weight portion 11c and the fixed electrode 12

Four

capacitance C between e and the capacitance C between + Y side of the small spindle 11c and the fixed electrode 12e The difference (c — C) is the measured capacity corresponding to the acceleration in the Y-axis direction. From this measured capacity,

4 3

It is possible to calculate the axial component of the measured acceleration when a relatively high G is added. In this case, since the measured capacitance is obtained from the difference in capacitance, it is possible to cancel the temperature characteristic.

[0038] When a relatively high G (for example, 60G) is added in the axial direction, the capacitance C between the small weight part 11c and the fixed electrode 12e, and the small weight part 11c and the fixed electrode 12e Capacitance between

1 1 3 2, capacitance C between the small weight portion l ie and the fixed electrode 12e, small weight portion 11c and the fixed electrode 12e

The sum of the capacitance C between 4 and 2 is the measured capacitance corresponding to the acceleration in the Z-axis direction. This measurement

Four

Constant-capacity force The z-axis direction component of the measured acceleration can be calculated. In this case, it is possible to cancel the temperature characteristic by providing a reference capacitance for detection in the Z-axis direction and subtracting the reference capacitance from the above-described sum of capacitances.

As described above, since the capacitance type acceleration sensor according to the present embodiment obtains the measurement capacitance from the difference in capacitance, it can accurately measure the acceleration regardless of the temperature change. . In addition, a large weight part and a small weight part are provided so that the large weight part swings when a relatively low G is added and the small weight part swings when a relatively high G is added. Therefore, it is possible to measure in multiple ranges. In addition, since the capacitive acceleration sensor according to the present embodiment divides the fixed electrode for the small spindle part into a plurality of parts, even when a relatively high G is applied, the acceleration component in the three-axis direction is obtained. Can be measured.

[0040] The present invention is not limited to Embodiments 1 and 2 described above, and can be implemented with various modifications. For example, the shapes of the movable electrode 11 and the fixed electrode 12 are not limited to the first and second embodiments, and can be implemented with various changes. In the present invention, the length, width, and thickness of the beam portion and the weight portion in the movable electrode 11 may be appropriately changed. For example, as shown in FIG. 7, the movable electrode 11 includes a first beam portion id that connects the frame body 11a and the small weight portion 11c, and a second shape that connects the weight portion l ib and the small weight portion 11c. It may be configured to have a beam portion 1 le or may be configured as shown in FIG. 8 so that a large amount of displacement can be obtained in the movable electrode 11.

In the above embodiment, as shown in FIG. 3, the force explaining the configuration in which the stopper layer 14 is provided on the fixed electrodes 12a and 12b. In the present invention, the mass of the movable electrode 11 A configuration that stops the oscillation and starts the oscillation of the small spindle is sufficient as shown in Fig. 9. Even if the stopper layer 14 is provided on the mass portions l ib, l ib, l ib, l ib

1 2 3 4

good.

[0042] According to the capacitive acceleration sensor of the present invention, the first substrate having a fixed electrode and the fixed electrode are arranged so as to face each other, and a capacitance to be measured is formed between the fixed electrode. A capacitance-type acceleration sensor that measures acceleration by changing the capacitance, and the movable electrode swings when a relatively low G is applied thereto. And a small weight portion that starts swinging when a relatively high G is applied, and the small weight portion constitutes a part of the weight of the large weight portion, and To provide a capacitive acceleration sensor that can accurately measure acceleration regardless of temperature changes, and can measure force in multiple ranges, since both rock when the mass part swings. Can do.

[0043] The present invention is not limited to Embodiments 1 and 2 described above, and can be implemented with various modifications.

For example, the thicknesses and materials of the electrodes and the respective layers described in the first and second embodiments can be set as appropriate without departing from the effects of the present invention. Further, the processes described in the first and second embodiments are not limited to this, and may be performed by changing the order of the steps as appropriate. Other modifications can be made as appropriate without departing from the scope of the object of the present invention.

Claims

The scope of the claims

[1] A first substrate having a fixed electrode, and a second substrate having a movable electrode that is arranged to face the fixed electrode and that forms a capacitance to be measured between the fixed electrode and the first substrate. A capacitive acceleration sensor that measures acceleration by a change in capacitance, wherein the movable electrode has a mass portion that starts swinging when a relatively low G is applied, and a relatively high G And a small weight part that starts swinging when added, and the small weight part constitutes a part of the weight of the large weight part, and swings together when the large weight part swings. Capacitance-type acceleration sensor.

[2] The fixed electrode has a first fixed electrode for a large weight part and a second fixed electrode for a small weight part, and the first fixed electrode is when a relatively high G is applied. 2. The capacitance type acceleration sensor according to claim 1, further comprising a stagger layer for preventing electrical contact with the mass portion.

3. The capacitive acceleration sensor according to claim 1, wherein the first fixed electrode is divided so as to be symmetrical with respect to two orthogonal axes on the electrode surface.

4. The capacitive acceleration sensor according to claim 3, wherein the second fixed electrode is divided so as to be symmetric with respect to each of the two orthogonal axes.

[5] The movable electrode includes a frame, a first beam portion that connects the frame and the large weight portion or the small weight portion, and a second that connects the large weight portion and the small weight portion. The capacitive acceleration sensor according to claim 1, further comprising a beam portion.

[6] The movable electrode includes a frame, a first beam portion that connects the frame and the large weight portion or the small weight portion, and a second that connects the large weight portion and the small weight portion. The capacitive acceleration sensor according to claim 2, further comprising a beam portion.

[7] The movable electrode includes a frame, a first beam portion that connects the frame and the large weight portion or the small weight portion, and a second that connects the large weight portion and the small weight portion. The capacitive acceleration sensor according to claim 3, further comprising a beam portion.

[8] The movable electrode includes a frame, a first beam portion that connects the frame and the large weight portion or the small weight portion, and a second that connects the large weight portion and the small weight portion. The capacitive acceleration sensor according to claim 4, further comprising a beam portion.