JPH0697234B2 - Piezoelectric impact sensor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable as an impact sensor using a shear-type piezoelectric element, and particularly as an impact sensor for vehicles, in which running vibration is constantly applied and a large impact impact is predicted. Provide what is used.

[0002]

2. Description of the Related Art A typical example of a conventional impact sensor using a shear-type piezoelectric element is, as shown in FIG. 4, a shear-type piezoelectric element 2 superposed on the surface of a metal substrate 1 and the shear-type piezoelectric element is placed on the surface thereof. The metal weight 3 is stacked, and the three members 1, 2 and 3 are bonded together via a conductive adhesive to form a laminated body. The shear type piezoelectric element 2, the substrate 1 and the weight 3 are stacked on each other. Surface contact is made via electrodes formed on the mating surface, and lead wires 4 and 5 are soldered to the substrate 1 and the weight 3 to form an electrode output end.

[0003]

However, in the above-mentioned impact sensor, since the laminated structure depends on the adhesion between layers, there is a risk of delamination. Particularly, traveling vibration is constantly applied and a strong collision impact is applied. In the case of a vehicle impact sensor, which is expected to cause such a problem, it is easy to induce the above-mentioned delamination, and there is a problem that reliability and safety are poor.

Further, conventionally, as described above, the lead wires 4 and 5 are wired to form the output ends of the respective electrodes of the shear type piezoelectric element. Therefore, the lead wires repeatedly move due to vibrations, often resulting in wire breakage accidents. Especially, in the case of the vehicle impact sensor, it is necessary to take measures to avoid the aerial wiring from the viewpoint of ensuring the reliability and safety.

[0005]

The present invention is provided to solve the above problems, and as a means therefor, each element forming the laminate is fastened with a belt (or the belt). And the adhesive are used together) while maintaining the laminated structure soundly, and by orienting the fastening direction of the belt in the sensitivity axis direction of the shear type piezoelectric element, the shearing direction of the shear type piezoelectric element (belt fastening direction, that is, belt The belt is configured to be tightened in a state in which it is difficult to move in the short width direction of the belt while ensuring a sound response in the longitudinal direction).

[0006] To restate, the present invention provides a piezoelectric impact sensor capable of maintaining the laminated structure soundly without delamination or decomposition by fastening the belt, and in addition, can properly respond to impact. It is possible to provide an impact sensor that does so (that secures responsiveness while fastening the belt).

According to the present invention, the belt is formed of a conductive material, the substrate is formed of a wiring board, and the belt end is connected to a wiring pattern of the wiring board to connect the belt to one of the shear type piezoelectric elements. The output terminals of both electrodes of the piezoelectric element can be formed by the wiring pattern by superposing the shear type piezoelectric element on another wiring pattern of the wiring substrate while using the conductive path of the electrode. Therefore, the wiring by the lead wire is eliminated and the reliability and safety are improved.

[0008]

FIG. 1 shows an embodiment of the present invention, and FIG. 2 shows another embodiment of the present invention. In each embodiment, 11 is a wiring board,
Reference numeral 12 denotes a shear-type piezoelectric element, 13 denotes a weight made of a conductive material, and the three members 11, 12, and 13 have an integrally laminated structure, and a belt 14 is used as the integral laminating means, or the belt 14 is used.
And conductive adhesive are used together. Reference numeral 15 denotes a backing plate of the laminated body. This backing plate forms, for example, a bottom plate of a casing for attaching the laminated body to an object to be measured, and in the drawing, a lid 16 is attached to the backing plate 15. Forming the casing,
It holds and holds the laminate.

The shear type piezoelectric element 12 has electrodes 12a, 12 on a pair of parallel surfaces which are the overlapping surfaces.
b is layered, and one electrode 12a is overlapped on the wiring pattern 11a of the wiring board 11 so as to establish continuity between them, and this wiring pattern is used as one output end of the (+) (-) pole.

Further, the weight 13 is superposed on the other electrode 12b so as to establish conduction between them, and in FIG. 1, a belt 14 made of a conductive material is wound around the weight 13 and both ends of the belt 14 are connected to the wiring board 11 Is fixed to another wiring pattern 11b by soldering or the like, and the shear type piezoelectric element 12, the weight 13 and the wiring substrate 11 are fastened to each other by the belt, and at the same time, the wiring pattern 11b is (+) (-). ) Use the other output end of the pole.

That is, the electrode 12b of the shear type piezoelectric element 12 is electrically connected to the weight 13, and the weight 13 is connected to the wiring pattern 11b via the belt 14, and the belt 14 forms a conductive path of the electrode 12b. It is also used as a means to do.

FIG. 1 shows an example of fastening the three members by a belt.
2 shows a case where both ends of the belt 14 are penetrated through the wiring board 11 as shown by imaginary lines and the belt 14 is fixed on the surface opposite to the element mounting side (the back surface side of the wiring board) of the board 11. In this case, a wiring pattern may be provided on the back surface of the wiring substrate 11 and the belt end may be fixed. Of course, while connecting the belt end to the wiring pattern 11b of FIG.
The wiring board 11 may be penetrated and fixed.

On the other hand, in FIG. 2, a wiring board 11, a shear-type piezoelectric element 12, and a weight 13 are mounted on a support plate 15 so that the wiring board 11 overlaps each other.
The belt 14 is wound around the belt 14 and both ends of the belt 14 are extended along both sides of the laminated body and soldered to the surface (mounting surface) of the backing plate 15, so that the laminated body is fastened to the backing plate 15. The support plate 15 is made of a conductive material, that is, a metal plate, and the belt end can be soldered to the surface of the metal plate. The support plate 15 made of this metal plate forms one output end of the electrode 12b of the shear type piezoelectric element 12. The wiring board 11 is interposed between the support plate 15 and the electrode 12a, and the wiring board 11 functions as an insulating spacer.

Further, as in the case of FIG. 1, both ends of the belt 14 are penetrated through the backing plate 15 as shown by phantom lines in FIG. 2, and the back surface of the backing plate, that is, the surface opposite to the laminated body mounting surface side. It can be configured to be fixed by.

The fastening direction of the belt 14 in FIGS. 1 and 2 is oriented in the direction of the sensitivity axis of the shear type piezoelectric element 12. More specifically, the shear type piezoelectric element 12 includes electrodes 12a, 12
Polarization is applied in a direction parallel to b, that is, in a direction parallel to the surface of the wiring board 11, the weight 13, and the support plate 15, and has a sensitivity axis W in this direction. When a shock is applied to the shear type piezoelectric element, a moment of inertia in the opposite direction is generated in the shear type piezoelectric element, a stress in the shear direction is generated in the piezoelectric element, and a voltage is generated. This voltage is output using the wiring pattern or the like as an output end.

Thus, the fastening direction of the belt 14 is oriented in the direction of the sensitivity axis W of the impact sensor as described above, whereby the shear type piezoelectric element 12 responds to the fastening direction (longitudinal direction) of the belt 14. The reaction works without being killed. On the contrary, the movement of the belt 14 in the width direction is strongly restrained and the fastening is strengthened.

As shown in FIG. 3, a weight with a band is previously formed on the weight 13 by spot welding or the like, the piezoelectric element 12 and the weight 13 are bonded, and this is bonded to the wiring board 11. Then, a temporary assembly is formed, and then both ends of the belt 14 are fixed to the wiring board 11 or the support plate 15 for fastening.

[0018]

As described above, according to the present invention, since the laminated elements forming the piezoelectric shock sensor are integrally fastened by the belt, delamination due to vibration or shock applied from the outside can be effectively prevented. The laminated structure is maintained sound.

Further, the present invention expects the fastening effect by the belt, and at the same time, by orienting the fastening direction of the belt in the sensitivity axis direction of the piezoelectric element, the piezoelectric element can be properly responded in the same sensitivity axis direction. Can be expected.

Further, according to the present invention, the above-mentioned belt is made to function as a conductive path and the wiring pattern of the wiring substrate is used as one output end, and another wiring pattern on which the piezoelectric element is overlapped is used as the other output end, and wiring by lead wires is performed. It is possible to provide a highly reliable and highly stable impact sensor for vehicles, which can be expected to have stable operation without the risk of disconnection due to vibration or impact, as well as being eliminated.

[Brief description of drawings]

FIG. 1 is a sectional view of a piezoelectric impact sensor using a shear type piezoelectric element according to an embodiment of the present invention.

FIG. 2 is a sectional view of a piezoelectric impact sensor showing another example.

FIG. 3 is a perspective view showing an example in which the belt and the weight in FIGS. 1 and 2 are made into a single component.

FIG. 4 is a cross-sectional view of a piezoelectric shock sensor using a conventional shear type piezoelectric element.

[Explanation of symbols]

 11 wiring board 12 shear type piezoelectric element 13 weight 14 belt 15 support plate

Claims (3)

[Claims] 1. A shear type piezoelectric element is stacked on a wiring board, a weight is stacked on the shear type piezoelectric element, and three members are fastened by a belt, and the fastening direction of the belt is set to a sensitivity axis of the shear type piezoelectric element. Piezoelectric impact sensor characterized by being oriented in the direction. 2. A weight of a shear type piezoelectric element is overlapped with a wiring pattern of a wiring board, and a weight made of a conductive material is stacked on the other electrode of the shear type piezoelectric element. Is fastened to the wiring board with a belt made of a conductive material, the fastening direction of the belt is oriented in the sensitivity axis direction of the shear type piezoelectric element, and the weight and the other wiring pattern of the wiring board are fastened to the belt. Piezoelectric impact sensor characterized by being electrically connected through. 3. A shear type piezoelectric element is stacked on a wiring board, a weight is stacked on the shear type piezoelectric element, and a stack of the weight, the shear type piezoelectric element and the wiring board is mounted on a backing plate. At the same time, the above-mentioned three members are fastened to the backing plate with a belt, and the fastening direction of the belt is oriented in the sensitivity axis direction of the shear-type piezoelectric element.