JPH0835983A - Capacitance type acceleration sensor - Google Patents

Abstract

PURPOSE:To obtain a sensor, which is hardly affected by parasitic capacitance, by making the longitudinal direction of a movable electrode perpendicular to the planar direction of a substrate, providing the movable electrode and fixed electrodes uprightly on the substrate, and making the acceleration detecting direction agree with the planar direction of the substrate. CONSTITUTION:Single-crystal silicon plates 31 are provided at the outsides of a pair of glass plates 5. Lead guiding-out electrodes 31a are provided on the plates. Fixed electrodes 6 are made to penetrate from the inner surfaces to the outer surfaces of the glass plates 5 and conducted to the silicon plates 31. An electrode is formed on a supporting part 3a. The electrode and the electrodes 31a are conducted to lead terminals 8 with wires 10. The longitudinal direction of a movable electrode 3 is provided vertically on the surface of a base 1 together with the glass plates 5 and the silicon plates 31. The acceleration detecting direction alpha is made to agree with the planar direction of the base 1. In this structure, the capacitances of two gaps on the both sides of the electrode 3 are similarly affected. Thus, the effect of the parasitic capacitance can be offset, and the output accuracy of the acceleration detection can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration sensor used in a device for measuring mechanical vibration, and relates to a capacitance type acceleration sensor made of a semiconductor, and particularly to a horizontal acceleration detection direction. The present invention relates to a capacitance type acceleration sensor which has improved output accuracy and improved workability.

[0002]

2. Description of the Related Art Conventionally, a capacitance type acceleration sensor for measuring mechanical vibration by interposing a movable electrode made of a semiconductor between fixed electrodes is well known, and it is well known in the art.
No. 69 or JP-A-4-152269 can be referred to. This type of capacitance type acceleration sensor is mounted on, for example, an automobile and is used exclusively for detecting acceleration in the horizontal direction.

FIGS. 8 to 10 show, for example, Japanese Patent Laid-Open No. 1-152.
FIG. 8 shows a sensor section of a conventional capacitance type acceleration sensor described in Japanese Patent No. 369, FIG. 8 is a side sectional view of the package after hermetically sealing, and FIG. 9 is a plan sectional view of the package after hermetically sealing. 10 is a partial side sectional view showing a state in which the acceleration detection direction is set to the horizontal direction. 8 is a sectional view taken along the line DD in FIG. 9, and FIG. 9 is a sectional view taken along the line EE in FIG.

In FIGS. 8 to 10, reference numeral 1 denotes a base made of metal or the like, which has a welded portion 1a formed on the outer peripheral portion and a through hole 1b formed for leading out a lead terminal (described later). Have Reference numeral 2 is a cap made of metal or the like that is combined with the base 1 to form a hermetic seal, and has a brim-shaped welded portion 2a formed on the outer peripheral portion facing the base 1. The base 1 and the cap 2 form a package, and the sensor element including the following elements 3 to 6 is arranged on the base 1.

Reference numeral 3 denotes a movable electrode made of a semiconductor such as silicon, which integrally has a support portion 3a serving as a fulcrum of the movable electrode 3 and a cantilever 3b serving as an elastic portion of the movable electrode 3. The supporting portion 3 a has an electrode deposited on the upper surface, supports the movable electrode 3 so as to surround the periphery thereof, and also functions as a spacer for the movable electrode 3. The cantilever 3b is thinly formed by etching a silicon plate from both sides.
And the supporting portion 3a are integrally connected to each other, and the movable electrode 3 is swingably supported with the supporting portion 3a as a fulcrum.

Reference numeral 4 denotes an insulating film for the electrodes formed on the supporting portion 3a, such as a thermal oxide film, 5 denotes a pair of insulating plates sandwiching the supporting portion 3a via the thermal oxide film 4, such as a glass plate, 6
Is a plate-shaped fixed electrode 6 fixed to the surface of each glass plate 5 facing the movable electrode 3. A gap is formed between the fixed electrode 6 and the movable electrode 3.

Reference numeral 7 is an adhesive for mechanically joining the sensor elements 3 to 6 onto the base 1, 8 is a lead terminal led out to the outside through the through hole 1b of the base 1, and 9 is a lead terminal 8. An insulating material filled so as to seal between the outer periphery and the through hole 1b, for example, hard glass, 10 is a wire made of gold wire or aluminum wire bonded to the lead terminal 8, and 11 is a wire 10 It is a lead extraction electrode that is electrically connected to the lead terminal 8. The lead extraction electrode 11 is arranged on the support portion 3a.

Reference numeral 12 is a sensor portion composed of the base 1 to the lead-out electrode 11. Further, in FIGS. 8 and 10, α is the acceleration detection direction, and G is the gravity direction. Therefore, FIG. 8 shows a case where vertical acceleration is detected, and FIG. 10 shows a case where horizontal acceleration is detected.

FIG. 11 shows, for example, Japanese Unexamined Patent Publication No. 4-152269.
FIG. 12 is a side sectional view showing a conventional acceleration sensor described in Japanese Patent Laid-Open Publication No. Gazette No. 12, G and α are the same as described above. In FIG. 11, reference numeral 20 denotes a bolt for mounting an acceleration sensor in which the sensor unit 12 is incorporated. Here, in order to set the acceleration detection direction α horizontally, the length of the sensor element (see FIGS. 8 to 10) is increased. The case where the direction is positioned so as to match the direction of gravity G is shown.

Reference numeral 21 is a housing on which the sensor portion 12 is mounted, 22 is a terminal integrally insert-molded with the housing 21, one end of which projects from the end surface of the housing 21, and 23 is a terminal 22 for extracting the output voltage to the outside. A wire made of a gold wire or an aluminum wire, etc., which is wire-bonded to the printed circuit board, 24 is a printed circuit board having an input / output electrode that is electrically connected to the terminal 22 via the wire 23, and 25 is mounted on the printed circuit board 24 and mounted on the sensor unit 1.
2 is a dedicated electronic integrated circuit for amplifying the output signal of No. 2.
The printed circuit board 24 is mounted with the sensor unit 12, the dedicated electronic integrated circuit 25 and the like, is electrically connected to the terminal 22 and is mechanically held.

Reference numeral 26 is an electrically insulating plate interposed between the printed circuit board 24 and the sensor section 12, 27 is a cover made of metal or the like mounted so as to cover the printed circuit board 24, and 28 is the cover 27. It is an adhesive for fixing to the housing 21. The cover 27 is a printed circuit board 24.
The upper sensor unit 12 and the dedicated electronic integrated circuit 25 are mechanically held, and the internal parts enclosed between the housing 21 and the housing 21 are protected.

Reference numeral 29 denotes a reinforcing bush interposed in the bolt penetration portion of the housing 21, and reference numeral 30 denotes a mounting surface of an acceleration detection target object to which the acceleration sensor is fixed via the bolt 20.

Next, the operation of the conventional capacitance type acceleration sensor will be described with reference to FIGS. First, in the manufacturing process, the silicon plate is etched from both sides to form the movable electrode 3 integrally connected to the support portion 3a and the cantilever 3b. Then, the movable electrode 3
Is sandwiched between the pair of glass plates 5 via the thermal oxide film 4 and the like,
An air gap is set between the fixed electrode 6 and the movable electrode 3 on each glass plate 5.

As described above, the movable electrode 3 elastically supported by the spring coefficient of the cantilever 3b and the glass plate 5 are provided.
A gap is formed between the upper fixed electrode 6 and the fixed electrode 6. The sensor portion 12 is mechanically joined to the base 1 via an adhesive 8. At this time, the movable electrode 3 that detects acceleration
Are arranged in the same direction as the mounting surface of the base 1, and detect only the acceleration applied in the acceleration detection direction α perpendicular to the mounting surface of the base 1.

That is, the movable electrode 3 is displaced in the empty space between the movable electrode 3 and the fixed electrode 6 according to the magnitude of the acceleration applied to the sensor section 12, and the electrostatic capacitance between the movable electrode 3 and the fixed electrode 6 is displaced. Changes according to the amount of displacement of the movable electrode 3. The amount of change in capacitance corresponds to, for example, the horizontal acceleration of the automobile.

In this way, the electric signal indicating the capacitance change output from the sensor section 12 is amplified by the dedicated electronic integrated circuit 25 on the printed circuit board 24, and the terminal 2
It is output to the outside via 2.

[0017]

As described above, the conventional electrostatic capacitance type acceleration sensor has the movable electrode 3 for detecting the acceleration.
Are arranged in the same direction as the mounting surface of the base 1, and only one of the pair of fixed electrodes 6 is arranged on the base 1 side. Therefore, only the electrostatic capacitance value between the movable electrode 3 and the one fixed electrode 6 is affected by the parasitic capacitance generated from the housing 21 holding the sensor unit 12 and peripheral members, so that the movable electrode 3 and the other fixed electrode are fixed. There is a problem that the capacitance value is different from that of the electrode 6 and the balance of the capacitance values between the two gaps is lost, which deteriorates the accuracy of acceleration detection.

Further, since the movable electrode 3 detects the acceleration applied in the direction perpendicular to the mounting surface of the base 1,
When it is attempted to detect an acceleration in the horizontal direction with respect to the ground surface as shown in FIG. 10, the sensor unit 12 is perpendicular to the acceleration detection direction α due to structural restrictions of the housing 21 that houses the sensor unit 12. It is necessary to fix it on the mounting surface and set the acceleration detection direction α of the sensor unit 12 to the horizontal direction.

That is, since it is necessary to mount the base 1 of the sensor unit 12 in a direction vertical to the ground surface, it is necessary to mount the sensor unit 12 in the housing 21 on a surface vertical to the mounting surface of the housing 21. , Housing 2
With regard to the layout configuration within 1, the number of parts increases and it becomes complicated,
There is a problem that an assembly error occurs and the accuracy of detecting acceleration is deteriorated. Further, since the components and the assembling work inside the housing 21 become complicated, the cost becomes high,
There was a problem that the cost reduction could not be realized.

Further, as shown in FIG. 11, when the sensor unit 12 is arranged so as to detect the acceleration in the vertical direction with respect to the mounting surface of the housing 21, and the acceleration in the horizontal direction with respect to the ground surface is detected, The mounting surface 30 of the object for detecting the acceleration is vertical to the ground surface. At this time, the acceleration sensor also needs to be mounted on the vertical mounting surface 30. For example, when mounting the acceleration sensor in a vehicle manufacturing line, the vertical surface needs to be preliminarily configured in the vehicle body. In the sheet metal stamping process, there is a problem that it is difficult to form a highly accurate vertical surface due to the draft of the press die.

Similarly, when an acceleration in the horizontal direction with respect to the ground surface is to be detected as shown in FIG. 11, the acceleration sensor is mounted on the vehicle body surface which is perpendicular to the ground surface and perpendicular to the acceleration detection direction α. Since it is necessary, the layout of the acceleration sensor mounting inside the vehicle body is limited, and the mounting process of the acceleration sensor is lateral, so that the mounting becomes complicated and the workability is poor, and the assembly work cost increases. There was a problem.

The present invention has been made in order to solve the above-mentioned problems, realizes cost reduction by improving workability, and is highly sensitive to parasitic capacitance and highly accurate electrostatic capacitance. The purpose is to obtain a type acceleration sensor.

[0023]

A capacitance type acceleration sensor according to a first aspect of the present invention is arranged so as to face a movable electrode which is displaced according to acceleration and a predetermined gap with respect to the movable electrode. A fixed electrode, and a substrate for electrically connecting and mechanically holding the movable electrode and the fixed electrode,
What is claimed is: 1. A capacitance type acceleration sensor for detecting acceleration by a change in capacitance between a movable electrode and a fixed electrode, wherein the movable electrode and the movable electrode are arranged such that a longitudinal direction of the movable electrode is perpendicular to a plane direction of a substrate. A fixed electrode is erected on the substrate so that the acceleration detection direction and the plane direction of the substrate coincide with each other.

According to a second aspect of the present invention, in the capacitance type acceleration sensor according to the first aspect, the length from the upper surface of the substrate to the tip of the movable electrode and the fixed electrode on the substrate side is defined as The length is set to be almost equal to the length in the longitudinal direction.

[0025]

According to the first aspect of the present invention, the movable electrode of the sensor portion is configured to be perpendicular to the substrate surface, and the acceleration detection direction is made coincident with the plane direction of the substrate. Offset to improve accuracy. Also,
It simplifies the assembly work for the frequently requested horizontal acceleration detection and realizes cost reduction.

According to a second aspect of the present invention, by increasing the distance between the substrate-side end surface of the movable electrode and the fixed electrode and the substrate, the capacitance generated between the substrate-side end surface of the fixed electrode and the substrate. The value is made sufficiently large with respect to the electrostatic capacitance value between the movable electrode and the fixed electrode to make it less susceptible to the fluctuation of the parasitic capacitance. As a result, the influence of the parasitic capacitance generated from the peripheral members is further suppressed, and the output accuracy of acceleration detection is further improved.

[0027]

【Example】

Example 1. (Corresponding to Claim 1) Hereinafter, a capacitance type acceleration sensor according to a first embodiment of the present invention will be described with reference to the drawings. 1 is a side sectional view showing a sensor portion of a capacitance type acceleration sensor according to a first embodiment of the present invention, and FIG. 2 is a plan sectional view taken along the line BB in FIG.
1 to 10, 12, G and α are the same as described above. 1 is a side sectional view taken along the line AA in FIG.

Reference numeral 31 is a semiconductor, for example, a single crystal silicon plate, which is arranged outside the pair of glass plates 5 and functions as an electrode, and 31a is a lead extraction electrode formed on the silicon plate 31. In this case, since the fixed electrode 6 penetrates from the inner surface to the outer surface of the glass plate 5 and is electrically connected to the silicon plate 31, and the glass plate 5 functions as an insulating film, the thermal oxide film 4 (see FIG. 8) is unnecessary. Become.

Although not shown, the same as above,
It is assumed that an electrode is formed on the support portion 3a, and the lead extraction electrode 31a and the electrode on the support portion 3a are electrically connected to the lead terminal 8 via the wire 10. Furthermore, the longitudinal direction of the movable electrode 3 is erected on the surface of the base 1 together with the glass plate 5 and the silicon plate 31, and the acceleration detection direction α coincides with the plane direction of the base 1.

The basic operation of the capacitance type acceleration sensor according to the first embodiment of the present invention shown in FIGS. 1 and 2 is the same as that described above, and therefore the description thereof is omitted here. In this case, the sensor elements 3 to 6 are mounted on the base 1 in an upright state so that the swinging direction of the movable electrode 3 is the same as the mounting surface of the base 1. Different from

That is, as shown in the figure, the movable electrode 3 of the sensor section 12 for detecting the acceleration is electrically and mechanically connected to the base 1 so that the acceleration detection direction α coincides with the horizontal direction. , Is supported vertically to the base 1.

Here, the mounting structure inside the housing of the capacitance type acceleration sensor shown in FIGS. 1 and 2 will be described with reference to FIG. In FIG. 3, 3, 12,
21, 22, 24, 25, 27, 28 and 30 are the same as described above.

The terminal 22 is integrally insert-molded with the housing 21 in order to draw the output voltage to the outside. In addition, the printed circuit board 24 is used for the sensor unit 12.
Dedicated electronic integrated circuit 2 which electrically connects and mechanically holds the output of the sensor unit 12 and processes the output of the sensor unit 12 as an amplified signal.
It is equipped with 5.

Reference numeral 39 is a connector integrally formed with the terminal 22. Reference numeral 42 denotes a shield cover disposed on the inner surface of the housing 21, which covers the sensor unit 12, the dedicated electronic integrated circuit 25, and the like, and functions as a shield member for protecting them from radio noise. Reference numeral 43 is a capacitor arranged between the terminal 22 and the shield cover 42. The shield cover 42 is soldered to the outer cylinder of the capacitor 43 and is connected to the ground wire of the terminal 22 via a bypass wire (not shown).

The cover 27 protects the components mounted in the housing 21 and seals the housing 21.
It is bonded integrally with the housing 21 by an adhesive 28. The capacitance type acceleration sensor configured in this way is
As shown in FIG. 3, it is mounted on a mounting surface 30 of an object for detecting acceleration.

As shown in FIG. 3, since the movable electrode 3 of the sensor section 12 of the electrostatic capacitance type acceleration sensor is configured to be perpendicular to the mounting surface 30, the influence on the parasitic capacitance is reduced. . That is, the influence of the parasitic capacitance can be canceled by being similarly affected by the electrostatic capacitance value between the two gaps on both sides of the movable electrode 3, and the balance can be maintained. Less susceptible to capacity.

When detecting the acceleration in the horizontal direction α with respect to the surface of the earth, by mounting the mounting flange portion (not shown) of the housing 21 on the horizontal surface with bolts or the like,
The acceleration in the horizontal direction α can be detected. At this time, since the assembling work is easy, the assembling work cost can be reduced, and the mounting layout of the acceleration sensor on the horizontal plane can be relatively easily and highly accurately configured in the vehicle body.

When the sensor unit 12 is assembled, it is possible to sequentially mount the printed circuit board 24 on the mounting surface of the housing 21 from the top, so that the number of components in the housing 21 can be reduced. You can Further, by mounting the housing 21 accommodating the sensor unit 12 on a horizontal surface with respect to the ground surface, it is not necessary to dispose the printed circuit board 24 vertically with respect to the mounting surface of the housing 21, and further downsizing and improvement in assembling accuracy can be achieved. It is possible to reduce the number of parts and the manufacturing cost. That is,
The work of mounting the housing 21 on the vehicle body is simplified, and the mounting cost is reduced.

Embodiment 2 FIG. Although the sensor unit 12 and the dedicated electronic integrated circuit 25 are mounted on the printed circuit board 24 in the first embodiment, the sensor unit 1 is mounted on the ceramic substrate or the like.
2 and the circuit elements of the dedicated electronic integrated circuit 25 may be directly mounted to realize miniaturization. A capacitance type acceleration sensor according to a second embodiment of the present invention, which has been further downsized, will be described below with reference to FIGS. 4 and 5.

FIG. 4 is a plan view of the second embodiment of the present invention seen from above, and FIG. 5 is a side sectional view taken along the line C--C in FIG.
In the figure, 3, 5, 7, 8, 10, 12, 22, 2
5, 31 and 31a are the same as described above. 35
Is a ceramic substrate having high insulation and strength and high heat dissipation, and is suitable for directly mounting a circuit device to form a hermetic seal in a small size. The sensor element is mounted on the ceramic substrate 35.

The supporting portion 3a and the cantilever 3b are formed by etching a silicon plate from both sides and are continuously provided integrally with the movable electrode 3, and the supporting portion 3a includes a pair of single crystal silicon plates through the glass plate 5 or the like. It is sandwiched by 31. Each of the pair of glass plates 5 has a plate-shaped fixed electrode 6 fixed to a portion facing the supporting portion 3a.

A gap is formed between the movable electrode 3 elastically supported by the cantilever 3b and the fixed electrode 6. The adhesive 7 mechanically bonds the sensor element to the base 1. The wire 10 is composed of a gold wire, an aluminum wire, or the like obtained by wire-bonding the lead-out electrode 31a of the sensor element and the lead terminal 8.

The sensor signal extracted from the wire 10 is introduced into the dedicated electronic integrated circuit 25. The terminal 22 is composed of three electric wires (a power supply line, a signal output line, and a ground line), and guides the sensor signal amplified by the dedicated electronic integrated circuit 25 to the outside.

Next, with reference to FIG. 4 and FIG. 5 together with the side sectional view of FIG. 6, a specific mounting structure in the housing of the capacitance type acceleration sensor according to the second embodiment of the present invention will be described. In FIG. 6, 3, 12, 21, 2
2, 25, 27, 28, 30, 35, 39, 42 and 43 are the same as described above.

Reference numeral 21a denotes a sensor portion 12 inside the housing 21.
24A is a printed circuit board for electrically connecting the terminal 22 integrally insert-molded to the housing 21, and 48 is an adhesive for bonding the sensor portion 12 including the ceramic substrate 35 to the mounting surface 21a.

As described above, by mounting on the ceramic substrate 35, the cap 2 (see FIG. 1) and the like are unnecessary, and the miniaturization can be realized without impairing the hermetic seal structure.

Example 3. (Corresponding to Claim 2) In the second embodiment, the length of the sensor element with respect to the longitudinal direction of the movable electrode 3 was not taken into consideration.
By setting the length from the substrate side of the sensor element to the tip of the movable electrode 3 and the fixed electrode 6 to be sufficiently long, for example, about the same as the length of the movable electrode 3, the influence of the parasitic capacitance may be further reduced. .

Hereinafter, referring to the side sectional view of FIG.
A third embodiment of the present invention in which the lengths from the substrate side of the sensor element to the tip ends of the movable electrode 3 and the fixed electrode 6 are set large will be described. In FIG. 7, 5a and 3
1b corresponds to the glass plate 5 and the silicon plate 31, respectively, and is 3, 6, 7, 10, 31, 31a and 3b.
5 is the same as described above.

Reference numeral 3c denotes a movable electrode facing end portion located on the ceramic substrate 35 side and facing the movable electrode 3, and 6a denotes an end surface of the fixed electrode 6 on the ceramic substrate 35 side. In this case, the glass plate 5a and the silicon plate 31b are configured to have a length 2L that is twice the length L of the movable electrode 3 in the longitudinal direction, and the length from the upper surface of the ceramic substrate 35 to the tip of the movable electrode 3 and the fixed electrode 6. Is L.

In this way, the fixed electrode 6 in the sensor section 12 is
End face 6a of the ceramic substrate 35 side and the ceramic substrate 3
5 is set to be long, the capacitance value generated between the end surface 6a of the fixed electrode 6 in the sensor element and the ceramic substrate 35 is configured between the movable electrode 3 and the fixed electrode 6. The capacitance value can be made sufficiently large.

Therefore, it is possible to reduce the influence of the variation of the parasitic capacitance, and it is possible to realize higher precision. Further, as in the above, when detecting the acceleration in the horizontal direction α with respect to the ground surface, the acceleration in the horizontal direction α can be detected by mounting the mounting flange portion (not shown) of the housing on the horizontal surface with bolts or the like. You can Also in this case, the assembling work can be facilitated, the assembling work cost can be reduced, and the acceleration sensor mounting layout on the horizontal plane can be relatively easily and highly accurately configured in the vehicle body.

That is, when detecting the acceleration in the horizontal direction (plane direction of the ceramic substrate 35) with respect to the ground surface,
Since it is not necessary to prepare a vertical surface with respect to the ground surface, it can be mounted on a horizontal surface and the assembling work becomes easy. Therefore, the acceleration sensor mounting layout on the horizontal plane, which is relatively easily and highly accurately configured in the vehicle body, is possible, and no assembly error occurs.

[0053]

As described above, according to the first aspect of the present invention, the movable electrode which is displaced according to the acceleration, the fixed electrode which is arranged to face the movable electrode with a predetermined gap, and the movable electrode. And a substrate for electrically connecting and mechanically holding fixed electrodes, and a capacitance type acceleration sensor for detecting acceleration by a capacitance change between a movable electrode and a fixed electrode, The movable electrode and the fixed electrode are erected on the substrate so that the longitudinal direction of the movable electrode is perpendicular to the plane direction of the substrate, and the acceleration detection direction and the plane direction of the substrate are aligned to prevent parasitic capacitance. The acceleration detection accuracy is improved by canceling out the influences that are caused by the above, and the assembly work is simplified for the horizontal acceleration detection that is frequently requested. Therefore, the workability is improved and the cost is reduced. Against High electrostatic capacitance type acceleration sensor of less susceptible accuracy influence Te has an effect to be obtained.

According to a second aspect of the present invention, in the first aspect, the length from the upper surface of the substrate to the tip of the movable electrode and the fixed electrode on the substrate side is substantially equal to the length of the movable electrode in the longitudinal direction. By setting them equal and increasing the distance between the substrate-side end surface of the movable electrode and the fixed electrode and the substrate, the electrostatic capacitance value generated between the substrate-side end surface of the fixed electrode and the substrate can be calculated. Since the capacitance value is made sufficiently large for the capacitance value between the two, it is less susceptible to the fluctuation of the parasitic capacitance, and the influence of the parasitic capacitance generated from the peripheral members is further suppressed to further improve the output accuracy of acceleration detection. There is an effect that a capacitive acceleration sensor can be obtained.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a capacitance type acceleration sensor according to Embodiment 1 (corresponding to claim 1) of the present invention, and shows a section taken along line AA in FIG.

FIG. 2 is a plan sectional view showing a capacitance type acceleration sensor according to a first embodiment of the present invention, and shows a section taken along line BB in FIG.

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

FIG. 4 is a plan view showing a state in which a capacitance type acceleration sensor according to a second embodiment of the present invention is viewed from above.

5 is a side sectional view showing a capacitance type acceleration sensor according to a second embodiment of the present invention, showing a section taken along the line C-C in FIG. 4. FIG.

FIG. 6 is a side sectional view showing an assembled state of the capacitance type acceleration sensor according to the second embodiment of the present invention.

FIG. 7 is a side sectional view showing a capacitance type acceleration sensor according to a third embodiment (corresponding to claim 2) of the present invention.

8 is a side sectional view showing a conventional capacitance type acceleration sensor, and is a side sectional view taken along the line DD in FIG.

9 is a plan cross-sectional view showing a conventional capacitance type acceleration sensor, and shows a cross section taken along line EE in FIG.

FIG. 10 is a side view showing, in a partially cross-sectional view, a standing state of a conventional capacitance type acceleration sensor.

FIG. 11 is a side sectional view showing a mounted state of an assembly of a conventional capacitance type acceleration sensor.

[Explanation of symbols]

1 base, 3 movable electrode, 6 fixed electrode, 6a end face of fixed electrode, 12 sensor part, 21 housing, 24
Printed board, 30 mounting surface, 35 ceramic board, α acceleration detection direction, L length in the longitudinal direction of the movable electrode.

Claims (2)

[Claims] 1. A movable electrode that is displaced according to acceleration, a fixed electrode that is opposed to the movable electrode with a predetermined gap, and the mechanical connection between the movable electrode and the fixed electrode. In a capacitance type acceleration sensor that includes a substrate for mechanically holding, and detects an acceleration by a capacitance change between the movable electrode and the fixed electrode, a longitudinal direction of the movable electrode is a plane of the substrate. The movable electrode and the fixed electrode are erected on the substrate so as to be perpendicular to the direction, and the detection direction of the acceleration and the plane direction of the substrate are matched with each other. Acceleration sensor. 2. The length from the upper surface of the substrate to the tip of the movable electrode and the fixed electrode on the substrate side is set to be substantially equal to the length in the longitudinal direction of the movable electrode. Capacitive acceleration sensor.