JPH08233847A - Acceleration sensor - Google Patents

Abstract

PURPOSE: To easily regulate a gap between a stopper and a weight by high accuracy by engaging the end of the stopper with the recess of the weight in a non-contact state. CONSTITUTION: A columnar weight 20 is fixed to the center of the lower surface of a movable board 2 in a hanging state, and a recess 21 of a circular section is formed at the center of the bottom. On the other hand the bottom wall 30 of a sensor is disposed under the weight 20. A threaded hole 31 which penetrates the wall 30 is provided at the corresponding position of the recess 21. A stopper 40 made of a rodlike thread member is engaged at the upper end with the hole 31 in the state protruding above the wall 30. A tapered part 41 having a small diameter toward upward is formed at the upper end of the stopper 30, and engaged in the state that a small gap exists to the peripheral edge of the recess 21 in a non-contact state. The gap between the stopper 40 and the weight can be regulated by regulating the screwed amount of the stopper 40.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration sensor for detecting acceleration.

[0002]

2. Description of the Related Art As an acceleration sensor, there is one in which a weight is provided on a movable substrate having a fixed peripheral end, and the acceleration is detected based on the deformation of the movable substrate when the acceleration acts on the weight. , Which has been conventionally known (for example, JP-A-4-19568).

A conventional example of this acceleration sensor is shown in FIG.
FIG. 5 shows a capacitance type acceleration sensor. In the figure, (1) is a circular fixed substrate that is horizontally arranged, and (2) is a circular movable substrate that is horizontally arranged below the fixed substrate. The fixed substrate (1) and the movable substrate (2) are pressed at their peripheral end portions by an upper pressing member (4) and a lower pressing member (5) with a spacer (3) interposed therebetween. As a result, the spacers (3) are arranged in parallel and face each other with a distance corresponding to the thickness of the spacers (3).

The fixed substrate (1) is composed of a printed wiring board, a circular electrode (6) is provided at the center of the lower surface of the fixed substrate (1), and the fixed electrode (1) is provided outside the circular electrode in the X-axis direction (left and right in FIG. Direction) and Y-axis direction (Fig. 5 (b))
Four sector-shaped divided electrodes (7a), (7b), (8a), and (8b) are provided at symmetrical positions in the vertical direction).

On the other hand, the movable substrate (2) is made of a flexible material such as thin-walled phosphor bronze or SUS, and the substrate itself is one common electrode (9). A circular capacitor (10) is formed in the central portion of the substrate between the common electrode (9) and the circular electrode (6) of the fixed substrate (1), and the common electrode (9) and each divided electrode are formed. (7
a) (7b) (8a) (8b) and four capacitors (11a) (11b) (12a) divided in the X-axis direction and the Y-axis direction.
(12b) is formed.

Further, a columnar weight (100) is fixed in a suspended state at the center of the lower surface of the movable substrate (2).

In the acceleration sensor shown in FIG. 5, for example, when acceleration is applied in the negative direction of the X axis (left direction in FIG. 5A), the weight (100) is moved in the positive direction in the X axis (right direction in FIG. 5A). Direction), an inertial force acts on the movable substrate (2) to generate a bending moment, and the movable substrate (2) is deformed as shown in FIG. By this modification, the right side of the common electrode (7) approaches the split electrode (7b), the left side of the common electrode (7) separates from the split electrode (7a), and the distance between the electrodes changes. The capacitance values of the capacitors (11a) and (11b) change, and the change in the capacitance is detected to detect the acceleration in the X-axis direction. Similarly, the acceleration in the Y-axis direction can be detected based on the capacitance change of the capacitors (12a) and (12b) in the Y-axis direction. Further, when acceleration is applied in the Z-axis direction (the direction in which the fixed substrate (1) and the movable substrate (2) face each other), the distance between the fixed substrate (1) and the movable substrate (2) increases or decreases, and the capacitor (10 ), The acceleration in the Z-axis direction can be detected.

As described above, the acceleration sensor is adapted to detect the acceleration based on the minute deformation of the movable substrate (2) when the acceleration is applied.

[0009]

When the deformation of the movable substrate (2) due to acceleration extends beyond the elastic deformation region to the plastic deformation region, permanent strain occurs in the movable substrate (2). Become. Therefore, even after the acceleration disappears, the initial state cannot be restored, which makes it impossible to detect the acceleration with high accuracy.

Therefore, in order to prevent deformation beyond a certain level, conventionally, as shown in FIG. 6, a stopper (110) formed of a surrounding wall in such a manner as to surround the peripheral surface and the bottom surface of the weight (100) at a minute interval. Is being placed. By doing so, even if an excessive acceleration is applied, the weight (100) contacts the stopper (110) and further displacement is prevented, so that the deformation of the movable substrate (2) beyond the elastic deformation region is prevented. be able to.

However, the amount of displacement of the weight (100) is several tens of μm in the normal acceleration measurement range, and even in the case of acceleration causing plastic deformation, it is extremely small, about 100 μm. The distance between the surfaces facing each other (100) and the stopper (110) must be set within 100 μm, which makes it difficult to adjust the gap with high accuracy.

As shown in FIG. 7, a weight (100) from the surrounding wall is provided on both sides in the X-axis direction, both sides in the Y-axis direction, and in the lower side in the Z-axis so that the gap can be adjusted with high precision.
A plurality of rod-shaped stoppers (120) protruding toward the side are provided, and the tip of the rod-shaped stopper (120) and the weight (100)
It is also considered to adjust the clearance between the outer surface and the outer surface. However, in this case, because there are multiple points for adjusting the gap,
There was a drawback that the adjustment was complicated.

Such a drawback similarly occurs not only in the capacitance type acceleration sensor but also in the piezoelectric type or piezoresistive type acceleration sensor.

The present invention has been made in view of the above technical background, and an object of the present invention is to provide an acceleration sensor capable of easily adjusting a gap between a stopper and a weight with high accuracy. .

[0015]

In order to achieve the above-mentioned object, the present invention, as shown with reference to the drawings, shows a weight (20) (20) on a movable substrate (2) having a fixed peripheral end. ′) Is provided, and the acceleration sensor is configured to detect the acceleration based on the deformation of the movable substrate (2) when the acceleration acts on the weight, the bottom surface of the weight (20) (20 ′) or the acceleration sensor. The recesses (21) (32) are provided in either one of the opposing walls (30) (30 ') with respect to the bottom surface, and the protruding stoppers (40) (22) are provided in the other, and the tip of the stopper is provided. A gist of an acceleration sensor is characterized in that a portion is fitted in the recess in a non-contact state.

Also preferably, the stoppers (40) (22)
Tapered part (41) that decreases in diameter toward the tip of the
(23) is formed, and the tapered portions (41) (2
It is better that only the part on the smaller diameter side of 3) is fitted in the recesses (21) (32), or further, the recesses (21) are provided on the bottom surface of the weight (20). On the other hand, it is preferable that the opposing wall (30) is provided with a stopper (40), and the stopper is formed by a screw member (40) which penetrates the opposing wall (30) and which can move back and forth.

[0017]

By adjusting the gap between the stopper and the recess, it is possible to adjust the gap in the X-axis direction, the Y-axis direction or even the Z-axis direction with one stopper.

Further, when a taper portion having a diameter decreasing toward the tip is formed at the tip portion of the stopper and only the portion on the diameter reducing side of the taper portion is fitted in the recess, the taper is formed. By changing the amount of retreat to the recess of the part,
Alternatively, the gap between the inclined surface of the tapered portion and the opening edge of the recess can be easily adjusted by changing the inclination angle of the tapered portion.

Further, when the bottom surface of the weight is provided with a recess and the opposing wall is provided with a stopper, and the stopper is formed by a screw member which is capable of advancing and retracting through the opposing wall, a gap is provided from the outside of the sensor. Adjustments can be made.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described based on an embodiment applied to a capacitance type acceleration sensor.

1 to 3 show a first embodiment of the present invention. In these figures, (1) is a fixed substrate,
(2) is a movable substrate, (3) is a spacer, (4) is an upper holding member, (5) is a lower holding member, (6) is a circular electrode provided on a fixed substrate, (7a) (7b) ( 8a) and (8b) are divided electrodes, (9) is a common electrode composed of a movable substrate, (10) is a circular capacitor formed in the central portion of both substrates, (11a)
(11b), (12a), and (12b) are four capacitors divided in the X-axis direction and the Y-axis direction, and these are the same as the configuration shown in FIG. Is omitted.

At the center of the lower surface of the movable substrate (2), a cylindrical weight (20) is fixed in a suspended state by a method such as bonding. In addition, a recess (21) having a circular cross section is formed in the center of the bottom surface of the weight.

On the other hand, below the weight (20), a sensor bottom wall (30) forming a housing of the sensor is arranged. The sensor bottom wall (30) is provided with a screw hole (31) penetrating the bottom wall at a position corresponding to the recess (21).
A stopper (40) formed of a rod-shaped screw member is screwed into the screw hole (31) with its upper end protruding above the sensor bottom wall (30).

As shown in detail in FIG. 2, a taper portion (41) is formed at the upper end of the stopper (40) so as to have a smaller diameter toward the upper side. Further, the inner diameter of the recess (21) is set to be smaller than the outer diameter of the stopper (40), and in this recess (21), the portion of the tapered portion (41) of the stopper (40) on the smaller diameter side is A slight gap (50) exists between the inclined surface (41a) and the peripheral edge (21a) of the opening of the recess (21), and they are fitted in a non-contact state. Further, the stopper (40) can freely set the amount of advance / retreat in the direction of the weight (20) by adjusting the amount of screwing. When the stopper (40) is advanced upward, the gap (50) between the inclined surface (41a) of the tapered portion (41) and the opening peripheral edge (21a) is reduced, and the stopper is moved downward. When retracted, the gap (50) expands conversely. Therefore, by adjusting the amount of advance / retreat of the stopper (40), the gap (50) between the tapered portion inclined surface (41a) and the opening peripheral edge (21a). ) Can be adjusted.

In the sensor shown in FIGS. 1 and 2, the X-axis direction (left and right direction in FIG. 1B) or the Y-axis direction (FIG. 1).
When acceleration is applied in the (up and down direction of (b)), the weight (20) tries to be displaced by receiving an inertial force in the direction opposite to the acceleration, but if the displacement is large, as shown in FIG. A portion of the peripheral edge (21a) of the opening of the place (21) opposite to the displacement direction hits the tapered inclined surface (41a) of the stopper (40) to prevent further horizontal displacement. When the weight (20) is displaced in the negative Z-axis direction (downward in Fig. 1 (a)), the entire peripheral edge (21a) of the opening abuts the tapered surface (41a) of the stopper (40). Then, further downward displacement is prevented. Therefore, excessive displacement of the weight (20) is prevented, and deformation of the movable substrate (2) beyond the elastic deformation region can be prevented.

Also, the displacement allowable amount of the weight (20) In other words, the size of the gap (50) between the peripheral edge (21a) of the recessed portion of the weight (20) and the tapered inclined surface (41a) of the stopper (40). This may be adjusted and set in advance by moving the stopper (40) forward and backward from the outside of the bottom wall (30) of the sensor.
By adjusting the amount of advance / retreat of the stopper (40), the X axis and Y
The gap (50) in the axial and Z-axis directions can be adjusted easily and simultaneously. Further, the gap (50) may be adjusted by changing the inclination angle of the tapered portion (41) of the stopper.

FIG. 4 shows another embodiment of the present invention. In this embodiment, a stopper is provided on the weight and a recess is provided in the bottom wall of the sensor. In addition, in FIG.
The same components as those in the embodiment shown in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted.

In the embodiment shown in FIG. 4, a stopper (22) having a circular cross-section protruding toward the sensor bottom wall (30 ') is provided integrally with the weight (20') at the center of the bottom surface of the weight (20 '). Has been. In addition, a taper portion (23) is formed at the tip of the stopper (22) so as to decrease in diameter downward.
On the other hand, a recess (32) having a circular cross section is formed on the upper surface of the sensor bottom wall (30 ') at a position corresponding to the stopper (22). The inner diameter of this recess (32) is equal to that of the stopper (22).
It is set smaller than the outer diameter of. The tapered portion (23) of the stopper (22) on the smaller diameter side has a slight gap (50 ') between the inclined surface (23a) and the peripheral edge (32a) of the opening of the recess (32). The recess (3
It is fitted in 2) in a non-contact state.

In the sensor shown in FIG. 4, when the weight (20 ') is about to be displaced in the X-axis direction or the Y-axis direction, when the displacement amount becomes large, the tapered surface (23a) of the tapered portion of the stopper (22).
) Collides with the peripheral edge (32a) of the recess opening, and further horizontal displacement is prevented. Further, when the weight (20 ') is displaced in the negative Z-axis direction (downward), the tapered surface (23a) of the stopper hits the entire peripheral edge of the opening to prevent further downward displacement. Therefore, the excessive displacement of the weight (20 ') is prevented, and the deformation of the movable substrate (2) beyond the elastic deformation region can be prevented. In this case as well, the stopper (2
Adjustment of the gap (50 ') between the inclined surface (23a) of the taper part (2) and the peripheral edge (32a) of the opening of the recess (32) depends on the amount of advance / retreat of the taper part (23) to / from the recess (32). It may be performed by changing the inclination angle of the taper portion (23).

In the above embodiment, the stopper (40) made of a screw member that can move back and forth on the sensor bottom wall (30).
If you install a stopper (2) on the bottom of the weight (20 ')
Although 2) is integrally provided, a stopper may be integrally provided on the bottom wall of the sensor, or the stopper on the bottom surface of the weight may be configured by a screw member that can advance and retreat. Further, although the embodiment applied to the capacitance type acceleration sensor has been shown, it is needless to say that the present invention may be applied to a piezoelectric type or piezoresistive type acceleration sensor.

[0031]

As described above, in the acceleration sensor according to the present invention, the bottom surface of the weight or the wall facing the bottom surface is provided with the recess, and the other is provided with the protruding stopper. Since the tip of the stopper is fitted in the recess in a non-contact state, the X-axis can be adjusted by one stopper by adjusting the gap between the stopper and the recess. The gap can be adjusted in the direction, the Y-axis direction, or the Z-axis direction, and the adjustment work can be extremely simple. Moreover, since it is not necessary to adjust a wide range of gaps like a stopper formed of a surrounding wall that surrounds the outer surface of the weight, it is possible to perform highly precise gap adjustment.

Further, in the case where a taper portion is formed at the tip end portion of the stopper, the diameter of which becomes smaller toward the tip end, and only the portion on the smaller diameter side of the taper portion is fitted in the recess, In addition to the effect, the gap between the inclined surface of the tapered portion and the opening edge of the recess can be easily adjusted by changing the amount of advance / retreat of the tapered portion to the recess, or by changing the inclination angle of the tapered portion, The gap adjustment work can be made simpler and easier.

In addition to the above effects, when the bottom surface of the weight is provided with a recess and the opposing wall is provided with a stopper, and the stopper is formed by a screw member that penetrates through the opposing wall and is movable back and forth. Since the gap can be adjusted from the outside of the sensor, the gap can be adjusted with higher accuracy, and the adjustment work can be further simplified.

[Brief description of drawings]

1A and 1B show a capacitance type acceleration sensor according to a first embodiment of the present invention, wherein FIG. 1A is a sectional view and FIG. 1B is a sectional view taken along line Ib-Ib of FIG. 1A.

2A is an enlarged cross-sectional view showing the vicinity of a stopper of the capacitance type acceleration sensor shown in FIG. 1, and FIG. 2B is II of FIG.
It is a b-IIb sectional view.

FIG. 3 is an enlarged cross-sectional view showing the vicinity of the stopper when acceleration is applied.

4A and 4B show a second embodiment of the present invention, in which FIG. 4A is a sectional view of a main part, FIG. 4B is an enlarged sectional view showing the vicinity of a stopper, and FIG. 4C is a IVc-IVc line of FIG. 4B. FIG.

FIG. 5 shows an example of a conventional acceleration sensor,
(A) is sectional drawing, (b) is the Vb-Vb sectional view taken on the line of (a).

6 is a cross-sectional view showing a state where acceleration is applied to the acceleration sensor shown in FIG.

FIG. 7 is a main-portion cross-sectional view showing another configuration example of the stopper in the conventional acceleration sensor.

[Explanation of symbols]

 2 ... Movable substrate 20, 20 '... Weight 21, 32 ... Recess 30, 30' ... Sensor bottom wall (opposing wall) 40, 22 ... Stopper 41, 23 ... Tapered part

Claims (3)

[Claims] 1. A weight (20) (20 ') is provided on a movable substrate (2) having a fixed peripheral end, and acceleration is generated based on deformation of the movable substrate (2) when acceleration acts on the weight. In the acceleration sensor designed to detect the above, the recesses (21) (3) are provided in either the bottom surface of the weights (20) (20 ') or the opposing walls (30) (30') with respect to the bottom surface.
2) is provided, and projecting stoppers (40) (22) are provided on the other side, and the tip end of the stopper is fitted in the recess in a non-contact state. . 2. A taper portion (41) (23) is formed at the tip of the stopper (40) (22), the diameter of which decreases toward the tip, and the diameter of the taper portion (41) (23) is small. The acceleration sensor according to claim 1, wherein only the side portion is fitted in the recesses (21) (32). 3. The weight (20) is provided with a recess (21) on the bottom surface thereof, while a counter wall (30) is provided with a stopper (40), and the stopper penetrates the counter wall (30) and is movable back and forth. 3. A screw member (40) formed by a screw member (40).
The acceleration sensor according to.