JPH10210766A - Oscillation suppressing mechanism for pasted piezoelectric element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a pasted piezoelectric element against fracture due to external force, e.g. impact. SOLUTION: A piezoelectric 12 is bonded to one side of a shim 11 to form a pasted piezoelectric element. The shim 11 is clamped by a fixed base 18 and a fixing block 19 in the vicinity of an end part opposite to a bonded part 15. A side wall 17 is coupled with the fixed base 18 and disposed on the side part of the pasted piezoelectric element. A planar oscillation suppressing mechanism 16 is fixed to the side wall 17 while being spaced apart by a specified distance from the part of the pasted piezoelectric element bonded with the piezoelectric. Since deformation due to impact and the like is prevented by the suppressing mechanism, pasted piezoelectric element can be protected against fracture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration damping mechanism for a bonded piezoelectric element used as an actuator or the like.

[0002]

2. Description of the Related Art FIG. 7 is a perspective view showing an example in which a displacement enlarging portion and a shielding portion are provided on a bonded piezoelectric element and used as a chopper for a pyroelectric infrared sensor.

A pyroelectric infrared sensor utilizes the pyroelectric effect of a pyroelectric body such as a LiTaO ₃ single crystal. The pyroelectric body has spontaneous polarization and always generates a surface charge. However, in a steady state in the atmosphere, the pyroelectric body is electrically neutral with the charge in the atmosphere. When infrared light is incident on the pyroelectric body, the temperature of the pyroelectric body changes, and accordingly, the charge state of the surface changes due to the neutral state being broken. A pyroelectric infrared sensor detects charges generated on the surface and measures the amount of incident infrared light. An object emits infrared rays according to its temperature, and by using this sensor, the position and temperature of the object can be detected.

[0004] The pyroelectric effect is caused by a change in the amount of incident infrared light. When detecting the temperature of an object as a pyroelectric infrared sensor, the amount of incident infrared light is intermittently opened or closed.
It must be changed forcibly. A mechanism used as this means is called a chopper, and forcibly interrupts the incident infrared rays to detect the temperature of the detection object.

In FIG. 7, 71 is a shim, 72 is a piezoelectric body, 73 is a displacement expanding portion, 74 is a sensor base, 75 is a fixture, 76a and 76b are fixing screws, 77 is a shim wiring,
Reference numeral 78 denotes a wiring for a piezoelectric body, 79 denotes an infrared detecting unit, 80 denotes an infrared light, and 81 denotes a shielding unit.

By bending an elastic plate made of phosphor bronze or a stainless steel alloy into a U-shape, the shim 71 and the displacement enlarging portion 73 are integrally formed, and the shim 71 and the displacement enlarging portion 73 are mutually connected by the joint portion. It is configured to have a longitudinal dimension in parallel and in the same direction. Further, in the displacement enlarging portion 73, a shielding portion 81 is formed at a right angle at a tip opposite to the coupling portion and on a side opposite to the shim 71. The piezoelectric body 72 is bonded to the surface of the shim 71 to form a piezoelectric bonded portion (unimorph element).

The shim 71 is sandwiched between the sensor pedestal 74 and the fixing member 75 near the end opposite to the joint with the displacement enlarging portion 73. The fixing screws 76
a, 76b. An infrared detecting section 79 is provided on the sensor base 74, and the displacement enlarging section 73 is provided.
It is located near the shielding part 81 at the tip. Sim 7
In the vicinity of the fixed portion 1, a shim wiring 77 is further provided, and a piezoelectric body 7 is further provided.
At the position opposite to the fixing portion of the shim 71 on the surface opposite to the bonding side of 2, the piezoelectric wiring 78 is attached. Here, when an AC signal is applied from the shim wiring 77 and the piezoelectric wiring 78, a potential difference is generated between the shim 71 and the piezoelectric body 72, and the coupling portion of the piezoelectric bonding portion with the displacement expanding portion 73 is displaced. Shielding part 8 at the tip of the displacement enlarging part according to
1 is also displaced, and by this movement, the infrared ray 80 incident on the infrared ray detecting section 79 is intermittently performed, and serves as a chopper.

Further, by making the resonance frequency of the chopper and the driving frequency close to each other, a large displacement enlarging effect can be obtained.

[0009]

As described in the prior art, a bonded type piezoelectric element which is fixed in a cantilevered manner generally has lower rigidity and lower resonance frequency than an element which is fixed at both ends, and the displacement of a vibrating portion is reduced. large. In general, a large opening / closing amount is required for an actuator generally used as an optical shutter. In particular, in the case of a chopper for a pyroelectric infrared sensor, in addition to the opening / closing amount, a gradual opening / closing operation is required to ensure sensitivity as a sensor. May be required.

For example, when a switching operation of 200 Hz or less is required and a large displacement is to be obtained by resonance driving,
It is necessary to adjust the rigidity of the bonded piezoelectric element itself used as a chopper to set the resonance frequency to 200 Hz or less. In this case, the rigidity of the bonded piezoelectric element decreases,
Be more susceptible to disturbances. When an impact force due to drop or the like is received in this state, the bonded piezoelectric element is greatly deformed by its own inertia, and causes problems such as buckling of the shim and cracking of the piezoelectric body.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a vibration damping mechanism capable of maintaining a stable characteristic without causing a problem such as deformation of a bonded piezoelectric element against external influences, especially impact force. .

[0012]

In order to solve this problem, the present invention provides a vibration damping mechanism such as a stopper near the bonded piezoelectric element.

Thus, the amount of deformation of the bonded piezoelectric element when receiving an impact force or the like can be suppressed to a range up to the vibration damping mechanism, and destruction can be prevented.

[0014]

DETAILED DESCRIPTION OF THE INVENTION According to the first aspect of the present invention, a laminated portion of an elastic member made of metal or the like and a piezoelectric body is provided.
A displacement member coupled to the lamination portion and vibrating in response to vibration of the lamination portion, fixing the elastic member in the vicinity of the lamination portion or the lamination portion, wherein the displacement member has a free end; A bonded piezoelectric element having a configuration capable of vibrating, wherein the bonded piezoelectric element is disposed in the vicinity with a distance equal to or more than a predetermined vibration displacement and contacts the bonded piezoelectric element when a displacement amount equal to or more than a predetermined displacement occurs. Since it is possible to suppress unnecessary deformation,
This has the effect of preventing the destruction of the bonded piezoelectric element.

According to a second aspect of the present invention, the resonance frequency caused by the vibration of the laminated portion of the elastic member and the piezoelectric member and the resonance frequency caused by the vibration of the displacement member are close to each other within 40% of the higher side. 2. The vibration damping mechanism for a bonded piezoelectric element according to claim 1, wherein the vibration is generated by applying an AC signal at a frequency between both resonances to generate vibration. When they are close to each other, both parts are greatly deformed at the same time due to an impact, etc., and the parts collide with each other, or more complex vibration is excited by the mutual deformation, and stronger deformation is applied to the bonded piezoelectric element. In some cases, it has the effect of preventing such deformation and unnecessary vibration.

According to a third aspect of the present invention, there is provided a vibration damping mechanism for a bonded piezoelectric element which is disposed near a bonded piezoelectric element having both resonance frequencies of 200 Hz or less. The bonded piezoelectric element having a low frequency, that is, having a small rigidity and a large amount of deformation due to inertial force, has an effect of suppressing unnecessary deformation and preventing destruction.

According to a fourth aspect of the present invention, the elastic member of the laminated portion and the displacement member are integrally formed by bending from the same flat plate, and the joint between the two and the other end of the displacement member are connected to the free end. 3. The piezoelectric element according to claim 2, wherein the piezoelectric element is disposed near the bonded piezoelectric element.
Or a vibration damping mechanism for the bonded piezoelectric element described in 3, wherein the vibration damping mechanism prevents an angle change of the bent portion due to an external force.

According to a fifth aspect of the present invention, there is provided a piezoelectric device in the vicinity of a bonded piezoelectric element in which one plane portion of a laminated portion and one plane portion of a displacement member face each other within ± 10 ° from parallel. 5. The vibration damping mechanism for a bonded piezoelectric element according to claim 4, wherein the laminated portion and the plane portion of the displacement member are opposed to each other because they are opposed to each other, and a destruction occurs at a contact portion or the like due to an external force. In some cases, it has the effect of preventing such destruction.

According to a sixth aspect of the present invention, in the bonded piezoelectric element according to the fifth aspect, the laminated piezoelectric element is located between the fixed part in the laminated part or the elastic member portion near the laminated part and the coupling part, and is laminated. This is a vibration damping mechanism for a bonded piezoelectric element that is disposed on the opposite side to the displacement member through the portion, and when bending occurs due to external force, the laminated portion and the vibration damping mechanism contact to prevent deformation, and A vibration damping mechanism is provided in the middle of the longitudinal direction, and comes into contact with a portion near the center of gravity of the bonded piezoelectric element, so that it has an effect of efficiently receiving the entire inertial force and preventing breakage.

According to a seventh aspect of the present invention, in the bonded piezoelectric element according to the fifth aspect, the laminated piezoelectric element is located between the fixed part in the laminated part or the elastic member portion near the laminated part and the coupling part, and is laminated. This is a vibration damping mechanism for a bonded piezoelectric element that is placed between the part and the displacement member.It is in contact with both the laminated part and the displacement member, damping it, suppressing the contact between them and the overall deformation, and It is a contact in a close part, and has the effect of efficiently preventing destruction.

According to an eighth aspect of the present invention, in the bonded piezoelectric element according to the fifth aspect, the piezoelectric element is located between the free end of the displacement member and the connecting portion, and is opposite to the laminated portion via the displacement member. This is a vibration damping mechanism for a bonded piezoelectric element that is disposed at a position, and has the effect of suppressing the amount of displacement by contact with a displacement member and making it possible to make contact near the center of gravity, thus effectively preventing destruction. .

According to a ninth aspect of the present invention, in the bonded piezoelectric element according to the fifth aspect, the piezoelectric element is located near the coupling portion,
And it is a vibration damping mechanism arranged on one side or both sides of the vibration direction, the coupling part is perpendicular to the displacement direction and the dimension is short, so the rigidity is relatively high, and the deformation of the contact point due to the contact with the vibration damping mechanism can be prevented It has such an effect.

According to a tenth aspect of the present invention, a flat portion substantially parallel to a longitudinal direction connecting the fixing portion to the connecting portion and a width direction orthogonal to the connecting portion is provided at a portion capable of contacting the bonded piezoelectric element. 6. The vibration damping mechanism for a bonded piezoelectric element according to any one of 6 to 9, wherein the contact portion is flat, so that a force applied to the bonded piezoelectric element at the time of contact can be dispersed, and destruction at the contact portion can be prevented. It has the effect of increasing safety.

According to an eleventh aspect of the present invention, the flat portion according to the tenth aspect is inclined substantially parallel to an inclination at the time of vibration with respect to a time when the bonded piezoelectric element is stopped. This is a vibration damping mechanism for the piezoelectric element. The inclination during vibration and the plane part of the vibration damping mechanism are parallel. Can be effectively prevented.

According to a twelfth aspect of the present invention, there is provided a vibration damping mechanism for a bonded piezoelectric element having a plurality of the vibration damping mechanisms according to the fifth aspect of the present invention. Vibration can be controlled, and vibration is controlled at a plurality of contact points, so that there is an effect that efficiency is improved and safety is increased.

According to a thirteenth aspect of the present invention, there is provided a vibration damping mechanism for a bonded piezoelectric element which is disposed near a bonded piezoelectric element used as an infrared opening / closing mechanism of a pyroelectric infrared sensor. A low-rigidity bonded piezoelectric element that functions as a chopper of a pyroelectric infrared sensor that needs to be opened and closed with low frequency and large displacement, It has the effect of preventing deformation and preventing destruction when frequency vibration is applied.

The same effect can be obtained with the vibration damping mechanism described above regardless of the material. Needless to say, by making the corners of the damping mechanism round, it is possible to prevent local contact between the bonded piezoelectric element and the corners of the damping mechanism. If the design permits, the same effect can be obtained even if each damping mechanism is a continuous body.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. (Embodiment 1) FIG. 1A is a perspective view showing an example of a bonded piezoelectric element having a displacement member, in which a vibration damping mechanism is provided near a piezoelectric body bonding portion, and FIG. 1B is a schematic side view. FIG.

In FIG. 1, 11 is a shim, 12 is a piezoelectric body, 13 is a displacement enlarging part, 14 is a shielding part, 15 is a coupling part,
Reference numeral 16 denotes a vibration damping mechanism, 17 denotes a side wall, 18 denotes a fixed base, and 19 denotes a fixture. Shim 11 and coupling part 15, displacement enlarging part 13,
The shielding part 14 is integrally formed by bending the same metal plate. A piezoelectric body 12 is adhered to one surface of the shim 11 to form a bonded piezoelectric element. The shim 11 is fixed between the fixing base 18 and the fixing tool 19 in the vicinity of the end opposite to the joint 15. The side wall 17 is connected to a fixed base 18 and is disposed on a side of the bonded piezoelectric element. The side wall 17 has a flat vibration control mechanism 1.
6 are attached, and are arranged at a fixed distance from the piezoelectric body bonding portion of the bonded piezoelectric element.

As shown in FIG. 1B, in the stationary state, the piezoelectric bonding portion of the bonded piezoelectric element and the vibration damping mechanism 1
6 are arranged at a fixed distance. This distance is a distance that does not make contact during normal driving vibration. When a force is applied from the outside due to dropping or the like, the bonded element generates bending due to its own inertial force or vibration excitation. At this time, when the deflection is large and the deformation is caused as indicated by the dotted line, the piezoelectric body bonding portion and the vibration damping mechanism 16 come into contact with each other, so that a larger deformation is not performed.

Thus, by providing the vibration damping mechanism in the vicinity of the bonded piezoelectric element as in the present configuration, it is possible to prevent bending deformation more than necessary and prevent the bonded piezoelectric element from being broken. Such a vibration damping mechanism has a resonance frequency of 200
This is effective when the rigidity is lower than Hz and the deformation is large.

(Embodiment 2) FIG. 2 is a side view showing an example in which a vibration damping mechanism is provided near a displacement member.

In FIG. 2, 21 is a shim, 22 is a piezoelectric body, 23 is a displacement enlarging part, 24 is a shielding part, 25 is a coupling part,
26 is a vibration damping mechanism. The vibration damping mechanism 26 includes the displacement enlarging unit 23
Are provided with a certain distance in the vicinity of. The other configurations are the same as in the first embodiment. The effect is also the same as that of the first embodiment, but in this case, the place of contact with the vibration damping mechanism is the displacement enlarging portion, which is particularly effective for deformation in the direction opposite to that of the first embodiment. Chipping or cracking of the piezoelectric body due to collision with the vibration mechanism can be prevented.

(Embodiment 3) FIG. 3 is a side view showing an example in which a vibration damping mechanism is provided between a displacement member and a piezoelectric body bonding portion.

In FIG. 3, 31 is a shim, 32 is a piezoelectric body, 33 is a displacement magnifying portion, 34 is a shielding portion, 35 is a coupling portion,
36 is a vibration damping mechanism. The vibration damping mechanism 36 includes the displacement enlarging unit 33
And the piezoelectric body bonding portion of the shim 31 are located with a distance equal to or more than a predetermined displacement amount, and the other configuration is the same as that of the first embodiment.

With this configuration, both the displacement enlarging portion and the piezoelectric body bonding portion come into contact with the vibration damping mechanism, and the first and second embodiments are used.
In addition, since the contact portion is a metal material portion, the contact portion is strong against collision and can prevent chipping of the piezoelectric body. In addition, it is possible to prevent breakage due to collision between the displacement enlarging portion and the piezoelectric bonding portion due to vibration due to external force.

(Embodiment 4) FIG. 4 is a side view showing an example in which an inclined flat portion is provided in a vibration damping mechanism.

In FIG. 4, 41 is a shim, 42 is a piezoelectric body, 43 is a displacement magnifying portion, 44 is a shielding portion, 45 is a coupling portion,
46 is a vibration damping mechanism. The vibration damping mechanism 46 is arranged in the vicinity of a piezoelectric body bonding portion, which is a laminated portion of the piezoelectric body 42 and the shim 41. The vibration damping mechanism 46 has a wide flat surface, and the flat surface has an inclination corresponding to the angle when the bonded piezoelectric element is deformed.

Regarding other structures, the first embodiment
Is the same as By providing the vibration control mechanism with a flat part,
The area at the time of collision is increased, and stress is prevented from being applied intensively to the bonded piezoelectric element, which leads to further prevention of destruction. In addition, by making the flat portion have the same inclination as the displacement angle of the bonded piezoelectric element at the time of collision, the contact on the flat surface becomes more complete and the effect is increased.

(Embodiment 5) FIG. 5 is a perspective view showing an example using a laminated piezoelectric element having a displacement member in a pyroelectric infrared sensor and a vibration damping mechanism.

In FIG. 5, 51 is a shim, 52 is a piezoelectric body, 53 is a displacement enlarging portion, 54 is a shielding portion, 55 is a coupling portion,
56a to 56d are vibration damping mechanisms, 57 is a side wall, 58 is a fixed base, and 59 is a pyroelectric infrared sensor.

The structure of the bonded piezoelectric element is the same as that of the first embodiment. The bonded piezoelectric element is fixed to a fixing base 58 at the end of the shim 51 by welding or the like. The fixed base 58 and the side wall 57 are connected to each other, and the side wall 57 is provided with vibration damping mechanisms 56a to 56d. The damping mechanisms 56a and 56b are arranged near the joint 55 so as to face each other with the joint therebetween. The vibration damping mechanism 56c is arranged near the piezoelectric body 52. Further, the vibration damping mechanism 56d is disposed between the displacement enlarging section 53 and the piezoelectric body bonding section. A pyroelectric infrared sensor is disposed near the shielding unit 54, and infrared light is intermittently intermittently moved by the reciprocating motion of the shielding unit.

With the plurality of vibration damping mechanisms described above, the bonded piezoelectric element has a vibration damping effect against external forces from various directions and can prevent deformation. Since the piezoelectric member is not provided in the coupling portion, there is no risk of breakage of the piezoelectric member, and since the rigidity is high, the coupling portion is not easily deformed by collision with the vibration damping mechanism. An optical shutter such as a chopper generally requires a large opening / closing amount, and for this reason, a resonance phenomenon may be used.

FIG. 6 shows the relationship between the driving frequency and the displacement of the shielding portion of the bonded piezoelectric element having this configuration. The bonded piezoelectric element of this configuration has a resonance frequency f1 caused by the vibration of the piezoelectric bonding portion and a resonance frequency f2 caused by the vibration of the displacement expanding portion. When the configuration is such that f1 and f2 are close to each other within about 40% of the higher side, a stable region in which the displacement hardly receives frequency dependency between the two resonances and is greatly enlarged appears. Therefore, by driving in this stable region, stable and large opening and closing can be performed.

When this method is used, it is necessary to set f1 and f2 near the driving frequency. In the case of a pyroelectric infrared sensor, if the switching frequency is too high, it is difficult to obtain sensitivity. For example, a frequency of 100 Hz or less is required. In this case, the two resonance frequencies are 200 Hz or less, which are low in rigidity, easily deformed by impact, and both the enlarged displacement portion and the piezoelectric bonding portion vibrate greatly to cause collision with each other, possibly leading to destruction.

However, by providing the vibration damping mechanism as in this configuration, it is possible to prevent the bonded piezoelectric element of the present drive system from being broken.

[0047]

As described above, the present invention can prevent deformation and destruction due to a drop impact or the like by providing a vibration damping mechanism for a bonded piezoelectric element. Further, by optimizing the position of the vibration damping mechanism and flattening the shape, it is possible to withstand various influences of external force. These vibration damping mechanisms are particularly effective for bonded elements with low resonance frequency, and are particularly effective when low driving frequency and large displacement are required, such as choppers for pyroelectric infrared sensors. is there.

[Brief description of the drawings]

FIG. 1A is a perspective view illustrating a configuration of a first embodiment of the present invention. FIG. 1B is a side view illustrating a configuration of the first embodiment.

FIG. 2 is a side view showing a configuration of a second embodiment of the present invention.

FIG. 3 is a side view showing a configuration of a third embodiment of the present invention.

FIG. 4 is a side view showing a configuration of a fourth embodiment of the present invention.

FIG. 5 is a perspective view showing a configuration of a fifth embodiment of the present invention.

FIG. 6 is a displacement characteristic diagram of a bonded piezoelectric element according to a fifth embodiment of the present invention.

FIG. 7 is a perspective view showing the configuration of a conventional bonded element unit.

[Explanation of symbols]

 11, 21, 31, 41, 51, 71 Shim 12, 22, 32, 42, 52, 72 Piezoelectric body 13, 23, 33, 43, 53, 73 Displacement enlargement section 16, 26, 36, 46, 56a to 56d Damping mechanism

Claims (13)

[Claims] And a displacement member that is coupled to the laminated portion and vibrates in response to vibration of the laminated portion. In the bonded piezoelectric element having a configuration in which the elastic member in the vicinity of the portion is fixed and the displacement member has a free end and can vibrate, the displacement type member is disposed in the vicinity with a distance of a predetermined vibration displacement or more, and A vibration damping mechanism for a bonded piezoelectric element that contacts the bonded piezoelectric element when a displacement amount occurs. 2. A configuration in which a resonance frequency caused by vibration of a laminated portion of an elastic member and a piezoelectric body and a resonance frequency caused by vibration of a displacement member are close to each other within 40% of a higher side, and a difference between both resonances is set. 2. The vibration damping mechanism for a bonded piezoelectric element according to claim 1, wherein the vibration control mechanism is arranged near the bonded piezoelectric element that generates vibration by applying an AC signal at a frequency. 3. The vibration damping mechanism for a bonded piezoelectric element according to claim 2, wherein said vibration damping mechanism is disposed near a bonded piezoelectric element having both resonance frequencies of 200 Hz or less. 4. A bonded piezoelectric element in which an elastic member of a laminated portion and a displacement member are integrally formed by bending from the same flat plate, and a joint between the two members and the other end of the displacement member are free ends. The vibration damping mechanism for a bonded piezoelectric element according to claim 2 or 3, which is disposed in the vicinity. 5. The piezoelectric device according to claim 4, wherein the one flat portion of the laminated portion and the one flat portion of the displacement member are disposed in the vicinity of the bonded piezoelectric element which is disposed within ± 10 ° from parallel with each other.
A vibration damping mechanism for a bonded piezoelectric element as described in the above. 6. The bonded piezoelectric element according to claim 5, wherein the displacement member is located between the fixed portion in the laminated portion or the elastic member portion in the vicinity of the laminated portion, and the coupling portion, and is connected to the displacement member through the laminated portion. Vibration suppression mechanism for bonded piezoelectric element placed on the opposite side. 7. The bonding type piezoelectric element according to claim 5, wherein the bonding portion is located between the fixed portion in the laminated portion or the elastic member portion near the laminated portion and the coupling portion, and between the laminated portion and the displacement member. Vibration damping mechanism for the bonded piezoelectric element. 8. The bonding type piezoelectric element according to claim 5, wherein the bonding type piezoelectric element is located between the free end of the displacement member and the coupling part, and is arranged on the opposite side of the laminated part via the displacement member. Vibration suppression mechanism for piezoelectric element. 9. The vibration damping mechanism for a bonded piezoelectric element according to claim 5, wherein the vibration element is located near the coupling portion and disposed on one or both sides in the vibration direction. 10. The device according to claim 6, wherein a flat portion substantially parallel to a longitudinal direction connecting the fixing portion to the connecting portion and a width direction perpendicular to the connecting portion is provided at a portion capable of contacting the bonded piezoelectric element. 6. The vibration damping mechanism for a bonded piezoelectric element according to item 5. 11. The vibration damping mechanism for a bonded piezoelectric element according to claim 10, wherein the plane portion is inclined substantially in parallel with the inclination of the bonded piezoelectric element when it is vibrated with respect to a stop. 12. A vibration damping mechanism for a bonded piezoelectric element having a plurality of vibration damping mechanisms according to claim 5. 13. The vibration damping mechanism for a laminated piezoelectric element according to claim 5, wherein the vibration damping mechanism is arranged near the laminated piezoelectric element used as an infrared opening / closing mechanism of the pyroelectric infrared sensor.