JP5362597B2 - Piezoelectric sensor - Google Patents

Description

  The present invention relates to a piezoelectric sensor capable of transmitting and receiving ultrasonic waves using mechanical vibration of a piezoelectric body.

This type of piezoelectric sensor can be used, for example, as a sensor for automatic doors, and is a non-contact detection sensor using ultrasonic waves as a detection medium.
Specifically, the piezoelectric sensor includes a piezoelectric body, and the piezoelectric body has a function of mutually converting mechanical energy and electrical energy (piezoelectric effect, inverse piezoelectric effect). For example, when a voltage is applied to the piezoelectric body, the piezoelectric body The body expands and contracts.

  And the structure of the vibrator | oscillator which combined the piezoelectric material and the diaphragm is disclosed (for example, refer patent document 1). Specifically, a vibrator including a piezoelectric body and a diaphragm is disposed on a pedestal, and a terminal is held on the pedestal. In addition, the vibrator and the terminal are electrically connected by a conductive wire, and when a voltage is applied to the piezoelectric body through the terminal and the conductive wire, the vibrator is bent and mechanically vibrated as the piezoelectric body expands and contracts ( Therefore, the piezoelectric sensor can transmit ultrasonic waves.

  When the transmitted ultrasonic wave is reflected by an object and the piezoelectric sensor receives the reflected ultrasonic wave, a voltage is obtained by the bending motion of the vibrator. Accordingly, the presence or absence of an object approaching the door and the distance to the object can be detected, and the automatic door control unit can output a drive signal to the door opening / closing motor.

Japanese Utility Model Publication No. 55-51568

However, the above-described conventional technology still has a problem regarding the reduction of the number of parts. That is, the piezoelectric sensor described in Patent Document 1 requires a separate housing that covers the periphery of the vibrator in the product state.
More specifically, when the operator inspects the product of the piezoelectric sensor or mounts the piezoelectric sensor on the circuit board, it is not preferable to touch the vibrator in terms of maintaining its performance, and even after mounting on the circuit board. In order to avoid dust and the like from adhering to the vibrator, this vibrator is naturally protected by a housing.

In other words, in the case of the piezoelectric sensor described in Patent Document 1, the cylindrical housing and the pedestal are separate parts and the number of parts is increased, which makes it impossible to reduce the manufacturing cost.
It should also be noted that the piezoelectric sensor assembly or product inspection becomes difficult if the vibrator is simply covered with a cylindrical housing. This is because when the conductive wire is routed to the outside of the housing and connected to the terminal on the lower surface of the pedestal, the housing becomes an obstacle, and further, the arrangement state of the vibrator and the conductive wire cannot be confirmed from the outside.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a piezoelectric sensor that can solve the above-described problems and achieve reduction in manufacturing cost and ease of assembly.

  A first invention for achieving the above object is drawn from a piezoelectric body, a diaphragm that forms a vibrator capable of transmitting or receiving ultrasonic waves in combination with the piezoelectric body, and the vibrator. A conductive wire that conducts the vibrator and a terminal connected to the circuit board, a pedestal that supports the vibrator on a surface opposite to a surface that holds the terminal, and a erection along the periphery of the pedestal Each of which has a peripheral wall surrounding the vibrator, and a case in which the pedestal and the peripheral wall are integrally formed.

According to the first invention, the piezoelectric sensor has a vibrator formed of a piezoelectric body and a diaphragm, the vibrator can transmit or receive ultrasonic waves, and a conductive wire is drawn from the vibrator. ing. The vibrator is supported on the base of the case.
On the other hand, a terminal connected to the circuit board is held on the surface opposite to the surface that supports the vibrator in this pedestal, and these terminals and the vibrator are electrically connected through conductive wires. .

  Here, the vibrator is surrounded by a peripheral wall of the case and disposed on the inner peripheral side of the peripheral wall. The peripheral wall and the above-described pedestal are integrally formed. In this way, if the peripheral wall surrounding the vibrator and the pedestal that supports the vibrator are formed as one part, the number of parts can be reduced compared to the conventional structure in which the cylindrical housing and the pedestal are separate parts. The manufacturing cost of the piezoelectric sensor can be reduced. Also, the assembly of the piezoelectric sensor is facilitated.

A first aspect of the present invention is placed on the vibration Doko, further comprising an equalizer for amplifying ultrasonic, peripheral wall, of which communicated with the peripheral side and the outer peripheral side, arrangement of transducers relative to the base, or, It has a window part which can visually recognize the arrangement state of the conductive line with respect to this vibrator, or the mounting state of the equalizer with respect to this vibrator.
As described above, when the peripheral wall and the pedestal are formed of one component, the conductive wire is difficult to be routed to the outer peripheral side of the peripheral wall. This is because the vibrator is disposed on the inner peripheral side of the peripheral wall, and the terminal is held on the surface opposite to the surface supporting the vibrator.

According to 1st invention, the surrounding wall has a window part, The inner peripheral side and the outer peripheral side are connected. Therefore, the conductive wire drawn out from the vibrator can be routed from the inner peripheral side of the peripheral wall to the outer peripheral side of the peripheral wall through the window, and this conductive wire is connected to the upper end of the peripheral wall as viewed in the height direction of the case. Therefore, the vibrator and the terminal can be easily connected without having to be drawn toward the lower end of the peripheral wall.

  Furthermore, the operator can visually confirm the placement state of the equalizer with respect to the vibrator, the arrangement state of the conductive wires with respect to the vibrator, and the placement state of the vibrator with respect to the pedestal from the outer peripheral side of the peripheral wall through the window portion. As a result, the time required for product inspection of the piezoelectric sensor can be shortened, which also contributes to a reduction in the manufacturing cost of the piezoelectric sensor. Moreover, since it can always be visually confirmed from the outer peripheral side of the peripheral wall, the reliability of the piezoelectric sensor to be shipped is also improved.

According to a second aspect of the present invention, in the configuration of the first aspect, the peripheral wall completely communicates with the inner peripheral side and the outer peripheral side in the height direction of the case, and receives the conductive wire drawn from the vibrator. And a side opening that leads to the terminal.
According to the second aspect of the invention, in addition to the action of the first aspect, the side openings are all in communication between the inner peripheral side and the outer peripheral side in the height direction of the case. Even when the vibrator having the height is lowered along the height direction of the case, the vibrator can be arranged on the pedestal without the conductive wire touching the peripheral wall. As a result, the assembly property of the piezoelectric sensor is greatly improved while preventing breakage of the conductive wire.

According to a third invention, in the configuration of the first or second invention, the pedestal penetrates through the height direction of the case and communicates with the side opening to hold the conductive wire received in the side opening. Conductive wire holding holes are provided.
According to the third invention, in addition to the effects of the first and second inventions, the conductive wire is further routed from the vibrator to the outer peripheral side of the peripheral wall via the side opening, and then the conductive wire holding hole. Head to the terminal while being held at. Therefore, it can be avoided that the conductive wire directed from the outer peripheral side of the peripheral wall repels and returns to the outer peripheral side of the peripheral wall, and the assembly work of the piezoelectric sensor becomes easy.

Moreover, since it is not necessary to expose the conductive wire to the outer peripheral side of the peripheral wall, this point also contributes to prevention of damage to the conductive wire, and the conductive wire can connect the vibrator and the terminal with the shortest length. become.
According to a fourth aspect of the present invention, in the configuration of the first to third aspects, a surface for holding the terminal is provided with a space rib for ensuring a space between the surface and the circuit board.

According to the fourth invention, in addition to the effects of the first to third inventions, the space rib secures the space between the surface holding the terminal and the circuit board. Therefore, since the case does not contact the circuit board, the vibration on the case side can be prevented from being transmitted to the circuit board side. In addition, when the conductive wire is fixed to the terminal with solder, the solder portion can be released from the circuit board. Further, when the terminal is fixed to the circuit board with solder, the solder portion is attached to the case. Since it can be separated from the circuit board, damage to the circuit board and the case can be suppressed.

According to a fifth aspect of the invention, in the configurations of the first to fourth aspects of the invention, the surface for holding the terminal is provided with a polarity identifying protrusion for identifying the polarity of the terminal.
According to the fifth invention, in addition to the effects of the first to fourth inventions, the time required for assembling the piezoelectric sensor to the circuit board can be shortened. Furthermore, mounting of a piezoelectric sensor with an incorrect polarity is avoided, which contributes to improving the reliability of a module equipped with a piezoelectric sensor.

  According to the present invention, the peripheral wall that surrounds the vibrator and the pedestal that supports the vibrator are integrally formed, and it is possible to provide a piezoelectric sensor that can achieve low manufacturing cost and easy assembly.

It is an external appearance perspective view of the piezoelectric sensor of a present Example. It is a disassembled perspective view of the piezoelectric sensor of FIG. 1, and is a figure which shows the state before the assembly. It is a longitudinal cross-sectional view of the piezoelectric sensor of FIG. It is a rear view of the case of FIG. It is a side view of the case of FIG. It is a side view of the piezoelectric sensor of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an external perspective view of the piezoelectric sensor 1 of this embodiment as viewed from above, and FIG. 2 is an exploded perspective view of the piezoelectric sensor 1 before assembly as viewed from below. The piezoelectric sensor 1 is, for example, a non-contact detection sensor that is used in a sensor for an automatic door and uses ultrasonic waves as a detection medium.

  As shown in FIGS. 1 and 2, the piezoelectric sensor 1 mainly includes a vibrator 2 and a case 40, and the vibrator 2 is accommodated in the case 40. 1 and 2 corresponds to the bottom surface side of the case 40, and the piezoelectric sensor 1 has the bottom surface side of the case 40 facing the mounting surface of the circuit board (not shown) of the sensor. It is implemented in the state.

The vibrator 2 of the present embodiment is formed with a unimorph structure in which a piezoelectric ceramic (piezoelectric body) 10 is superposed on a metal diaphragm 20.
Specifically, the piezoelectric ceramic 10 is made of, for example, lead zirconate titanate ceramic (PZT) or the like, and has a predetermined thickness in the height direction of the case 40 (vertical direction in FIGS. 1 and 2) ( FIG. 3). Although the shape of the piezoelectric ceramic 10 is not particularly limited, a substantially square flat plate can be given as an example here.

  As shown in FIGS. 2 and 3, one lead wire (conductive wire) 16 is fixed with solder 18 at an appropriate position on the other surface 14 of the piezoelectric ceramic 10. The lead wire 16 of this embodiment is a gold thread wire, but a covered wire or a copper wire may be used.

A diaphragm 20 is superimposed on the upper side of the piezoelectric ceramic 10.
Specifically, the diaphragm 20 is also a circular flat plate having a predetermined thickness in the height direction of the case 40 (FIG. 3), and is formed to have a size that can inscribe the four corners of the piezoelectric ceramic 10. . Then, in order to apply vibration of the piezoelectric ceramic 10 to the diaphragm 20 to obtain a large vibration, the piezoelectric ceramic 10 and the diaphragm 20 are overlapped, and the back surface 24 of the diaphragm 20 and one surface 12 of the piezoelectric ceramic 10 are bonded with an adhesive. Glued. In FIG. 3, the thicknesses of the piezoelectric ceramic 10 and the diaphragm 20 are exaggerated to help understand the structure.

  One lead wire (conductive wire) 26 is also fixed at an appropriate position on the back surface 24 of the diaphragm 20 with solder 28 (FIGS. 2 and 3). Is a line.

  On the other hand, a metal horn (equalizer) 30 is placed on the surface 22 of the diaphragm 20 (FIG. 3). The horn 30 is formed in a substantially mortar shape and is expanded in a direction away from the diaphragm 20. The lower end portion of the horn 30 having a reduced diameter is bonded to the substantially central position of the surface 22 of the diaphragm 20. A predetermined coating is applied to the expanded surface of the horn 30 visible in FIG.

Here, the case 40 of the present embodiment is formed in a cup shape made of plastic resin, and the pedestal 42 forming the cup-shaped bottomed portion and the peripheral wall 70 having an opening portion are integrally formed. .
Specifically, as shown in FIG. 3, first, the pedestal 42 is formed in a substantially cylindrical shape and includes an upper surface 44 that supports the vibrator 2.

A support rib 46 projects from the upper surface 44 of the present embodiment toward the vibrator 2. The support rib 46 is formed in a cylindrical shape, and has a flat tip surface 47 that is annularly closed and this tip surface 47 is in contact with the other surface 14 of the piezoelectric ceramic 10.
A cylindrical adhesive portion 48 is also formed on the inner peripheral side of the support rib 46, and the other surface 14 of the piezoelectric ceramic 10 is fixed and supported with an adhesive.

  Specifically, the bonding portion 48 is formed at a mechanical vibration node (a position where the amplitude becomes zero) generated in the vibrator 2. In the case of the circular vibrator 2 as in the present embodiment, the adhesive portion 48 is on the circumference of the diameter φ of the vibrator 2 because the piezoelectric ceramic 10 is bent by expansion and contraction in the width direction and the length direction. Supports a position closer to the center by φ / 4.

This is because the vibrator 2 of this embodiment is driven by the voltage of the natural resonance frequency, and the vibration node at that time is a position near the center by φ / 4 from the circumference of the diameter φ, In other words, it is located on the circumference having a diameter of about φ / 2 with respect to the center of the vibrator 2.
Although the expansion and contraction is smaller than the expansion and contraction that occurs in the width direction and the length direction of the piezoelectric ceramic 10, the expansion and contraction also occurs in the thickness direction of the piezoelectric ceramic 10.

On the other hand, the pedestal 42 includes a lower surface 54 facing the mounting surface of the circuit board described above.
As shown in FIG. 3, terminal holding portions 56 and 56 are formed at appropriate positions on the lower surface 54 to hold the terminals 80 and 82 having a square cross section and project toward the mounting surface.

  Spacers (space ribs) 58 and 60 are provided in the vicinity of the periphery of the lower surface 54 (FIGS. 2, 4, and 5). The spacers 58 and 60 are formed in a substantially rectangular parallelepiped shape, and the longitudinal direction thereof extends along the lower surface 54. The spacers 58 and 60 are arranged at symmetrical positions with respect to the center of the lower surface 54, and can contact the mounting surface. This secures a space between the lower surface 54 and the mounting surface. Therefore, since the lower surface 54 does not contact the circuit board, the vibration on the case 40 side can be prevented from being transmitted to the circuit board side. Further, when the lead wires 16 and 26 are fixed to the terminals 80 and 82 with the solders 86 and 88 as in the present embodiment, the solder 86 and 88 portions can be released from the circuit board. When 80 and 82 are fixed to the circuit board with solder, the solder portion for fixing the terminals can be separated from the lower surface 54, so that the resin case 40 can be prevented from melting.

4 is a rear view of the case 40 of FIG. 2, and FIG. 5A is a side view of the case 40 as viewed from above. FIG. 5B is a side view of the case 40 when FIG. 4 is viewed from the left (FIG. 5A is viewed from the left).
Further, one of the spacers 58 and 60 is provided with a pin (polarity identification protrusion) 62 for identifying the polarity of the terminals 80 and 82. Although the pin 62 of this embodiment is provided on the spacer 60, it may be provided on the lower surface 54 as long as it has a shape and can identify the polarities of the terminals 80 and 82, not just a mark.

Here, the pedestal 42 includes protective portions (conductive wire holding holes) 64 and 64 in the vicinity of the periphery thereof (FIG. 4).
Specifically, the protection parts 64 and 64 are holes having a substantially rectangular shape in plan view that are formed through the upper surface 44 and the lower surface 54 in the height direction of the case 40. The longitudinal directions of the protective portions 64, 64 do not extend toward the center of the upper surface 44 or the lower surface 54, but extend in an oblique direction toward, for example, the other spacer 58 of the spacers 58, 60 described above (see FIG. 2, FIG. 4), the lead wires 16 and 26 can be held and protected. The point at which the lead wires 16 and 26 are held by the protection portions 64 and 64 will be described later.

Next, the peripheral wall 70 is erected so as to extend upward from the peripheral edge of the pedestal 42.
Specifically, as shown in FIGS. 3 to 5, the peripheral wall 70 of this embodiment has a lower end 74 positioned substantially at the same height as the lower surface 54 of the base 42, and extends upward from the lower end 74. . The upper surface 44 of the pedestal 42 and the sides of the vibrator 2 and the horn 30 are further extended upward, and a circular upper opening 72 is provided at the upper end thereof.

By the way, the peripheral wall 70 has a portion where the inner peripheral side and the outer peripheral side are completely communicated with each other over the height direction of the case 40.
Specifically, the peripheral wall 70 of the present embodiment has conductive wire receiving openings (side openings) 76, 76 (FIG. 2). The conductive wire receiving openings 76 and 76 are respectively provided corresponding to the positions of the above-described protective portions 64 and 64 (FIGS. 3 to 5), and open upward with a width capable of receiving at least the lead wires 16 and 26. From the 72 to the lower end 74, it penetrates the inner peripheral side and the outer peripheral side of the peripheral wall 70, respectively.

The conductive wire receiving opening 76 is connected to the corner portion closest to the periphery of the lower surface 54 among the corner portions of the protective portion 64 at a position facing the pedestal 42 (FIGS. 3 and 4). The outer peripheral side of the peripheral wall 70 communicates with the conductive wire receiving opening 76.
On the other hand, the conductive wire receiving openings 76, 76 of the present embodiment have horn window portions (window portions) 78, 78 at positions facing the vibrator 2 and the horn 30, respectively.

The horn windows 78 and 78 are opened with a width much larger than the width capable of receiving the lead wires 16 and 26, and the horn window portions 78 and 78 span a narrow portion of the conductive wire receiving opening 76 in the circumferential direction of the peripheral wall 70. (FIG. 5B).
Returning to FIG. 2 again, for assembling the piezoelectric sensor 1, first, the case 40 holding the terminals 80 and 82 is prepared, and the vibrator 2 including the lead wires 16 and 26 is lowered toward the base 42.

At that time, the lead wires 16 and 26 are respectively received by the wide portions of the conductive wire receiving openings 76 and 76 located in the upper opening 72, that is, the horn window portions 78 and 78, and from the horn window portions 78 and 78 to the peripheral wall 70. It is pulled out to the outer peripheral side.
Subsequently, the vibrator 2 is lowered toward the upper surface 44, the other surface 14 of the vibrator 2 is brought into contact with the support rib 46, and the vibrator 2 is bonded and fixed by the bonding portion 48.

  Next, the lead wire 16 drawn out to the outer peripheral side of the peripheral wall 70 through the horn window 78 is gripped by the operator and drawn into the protective portion 64 from the narrow portion of the nearby conductive wire receiving opening 76. The As a result, as shown in FIG. 3, the side surface portion of the lead wire 16 is held on the inner wall of the protection portion 64, and the leading end portion of the lead wire 16 is pulled out below the lower surface 54.

  The lead wire 26 drawn out to the outer peripheral side of the peripheral wall 70 through the horn window 78 is drawn into the protection portion 64 from the narrow portion of the conductive wire receiving opening 76 in the vicinity thereof. Therefore, the side surface portion of the lead wire 26 is held on the inner wall of the protection portion 64, and the tip portion of the lead wire 26 is pulled out below the lower surface 54 (FIGS. 3 and 6). FIG. 6 shows a state in which the vibrator 2 and the like are arranged in the case 40 viewed from the direction of FIG.

Then, the lead wire 16 is wound around the peripheral surface 81 of the terminal 80 in the vicinity of the lower surface 54 and fixed with the solder 86 (FIG. 3), and the lead wire 26 is also wound around the peripheral surface 83 of the terminal 82 in the vicinity of the lower surface 54. When the solder 88 is fixed (FIGS. 3 and 6), the vibrator 2 and the terminals 80 and 82 are electrically connected.
Thereafter, when the horn 30 is bonded to the surface 22 of the diaphragm 20, the piezoelectric sensor 1 is completed.

The piezoelectric sensor 1 configured as described above can transmit and receive ultrasonic waves, the spacers 58 and 60 are mounted on the mounting surface of the circuit board of the sensor, and the terminals 80 and 82 are electrically connected to the circuit portion. Connected.
When a voltage is applied to the piezoelectric ceramic 10 via the terminals 80 and 82 and the lead wires 16 and 26, the thickness direction of the piezoelectric ceramic 10 and the width direction and length direction of the piezoelectric ceramic 10 orthogonal to the thickness direction expand and contract ( Inverse piezoelectric effect).

  The expansion and contraction of the piezoelectric ceramic 10 in the width direction and the length direction becomes a force that bends the entire vibrator 2, and ultrasonic waves are generated by mechanical vibration caused by the bending motion of the vibrator 2. Note that the generated ultrasonic wave is amplified by the horn 30. As described above, the piezoelectric sensor 1 can convert an electric signal into an ultrasonic wave and transmit the ultrasonic wave toward the object from the upper opening 72 side.

On the other hand, when the transmitted ultrasonic wave propagates through the air and collides with an object, it is reflected toward the piezoelectric sensor 1.
The piezoelectric sensor 1 can convert the received ultrasonic wave into an electric signal. Specifically, when the piezoelectric sensor 1 receives the reflected ultrasonic wave via the horn 30, the piezoelectric ceramic 10 expands and contracts with the bending motion of the vibrator 2, and a voltage can be obtained (piezoelectric effect). .

As described above, the piezoelectric sensor 1 can transmit and receive ultrasonic waves by using the piezoelectric effect and the inverse piezoelectric effect.
The automatic door control unit using the piezoelectric sensor 1 can detect the presence / absence of an object approaching the door and the distance to the object, and can output a drive signal to a door opening / closing motor.

As described above, according to the present embodiment, the piezoelectric sensor 1 has the unimorph vibrator 2 formed of the piezoelectric ceramic 10 and the vibration plate 20, and the vibrator 2 can transmit and receive ultrasonic waves and vibrate. Lead wires 16 and 26 are drawn out from the child 2. The vibrator 2 is supported on the upper surface 44 of the base 42.
On the other hand, terminals 80 and 82 connected to the circuit board are held on the lower surface 54 of the pedestal 42, and these terminals 80 and 82 and the vibrator 2 are electrically connected via the lead wires 16 and 26. Has been.

  Here, the vibrator 2 is disposed on the inner peripheral side of the peripheral wall 70, and the peripheral wall 70 and the above-described pedestal 42 are a case 40 formed integrally. Thus, if the peripheral wall 70 surrounding the vibrator 2 and the pedestal 42 that supports the vibrator 2 are formed as one component, the conventional structure, that is, a structure in which the cylindrical housing and the pedestal are separate components. Compared to the above, the number of parts is reduced, and the manufacturing cost of the piezoelectric sensor 1 can be reduced. Further, since the housing does not have to be placed on the pedestal, assembly of the piezoelectric sensor 1 is facilitated.

In addition, if the peripheral wall 70 and the base 42 are formed by one component, the lead wires 16 and 26 are difficult to be routed to the outer peripheral side of the peripheral wall 70. This is because the vibrator 2 is disposed on the inner peripheral side of the peripheral wall 70, while the terminals 80 and 82 are held on the lower surface 54 of the base 42.
However, conductive wire receiving openings 76, 76 are formed in the peripheral wall 70, and the inner peripheral side and the outer peripheral side communicate with each other.

  Therefore, the lead wires 16 and 26 drawn out from the vibrator 2 can be routed from the inner peripheral side of the peripheral wall 70 to the outer peripheral side of the peripheral wall 70 via the conductive wire receiving openings 76 and 76. 26 does not have to be routed from the upper opening 72 toward the lower end 74 via the outer peripheral side of the peripheral wall 70, and the vibrator 2 and the terminals 80 and 82 can be easily connected.

  Further, since the conductive wire receiving openings 76 and 76 are all in communication between the inner peripheral side and the outer peripheral side in the height direction of the case 40, the vibrator 2 having the lead wires 16 and 26 is connected to the case. The vibrator 2 can be disposed on the pedestal 42 without the lead wires 16 and 26 touching the peripheral wall 70 even when lowered along the height direction of 40. As a result, the assembling property of the piezoelectric sensor 1 is significantly improved while preventing the lead wires 16 and 26 from being damaged.

  Furthermore, in the component parts of the piezoelectric sensor 1, the lead wires 16 and 26 and the horn 30 are components that are slightly inferior in strength in nature, but as shown in FIG. The placement state of the lead wires 16 and 26 with respect to the vibrator 2 and the placement state of the vibrator 2 with respect to the base 42 can be visually confirmed from the outer peripheral side of the peripheral wall 70 through the horn window portions 78 and 78. . As a result, the time required for product inspection of the piezoelectric sensor 1 can be shortened, which also contributes to a reduction in the manufacturing cost of the piezoelectric sensor 1. Moreover, since it can always be visually confirmed from the outer peripheral side of the peripheral wall, the reliability of the piezoelectric sensor 1 to be shipped is also improved.

  Furthermore, the lead wires 16 and 26 are routed from the vibrator 2 through the conductive wire receiving openings 76 and 76 to the outer peripheral side of the peripheral wall 70 and then held by the protection portions 64 and 64 in the terminal 80. , 82. Therefore, it is possible to avoid the lead wires 16 and 26 from the outer peripheral side of the peripheral wall 70 toward the terminals 80 and 82 from repelling and returning to the outer peripheral side of the peripheral wall 70, and the assembly work of the piezoelectric sensor 1 is facilitated.

In addition, since it is not necessary to expose the lead wires 16 and 26 to the outer peripheral side of the peripheral wall 70, this point also contributes to preventing damage to the lead wires 16 and 26, and the lead wires 16 and 26 are vibrators. 2 and the terminals 80 and 82 can be connected with the shortest length.
Further, the spacer 60 is provided with a pin 62 for identifying the polarity of the terminals 80 and 82. Therefore, the time required for assembling the piezoelectric sensor 1 to the circuit board can be shortened. Furthermore, since mounting of the piezoelectric sensor 1 having the wrong polarity is also avoided, it contributes to improving the reliability of the module on which the piezoelectric sensor 1 is mounted.

The present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the claims.
For example, although the piezoelectric sensor of the above embodiment is configured to be able to transmit and receive ultrasonic waves, the piezoelectric sensor of the present invention may have either a transmission function or a reception function. In addition to the automatic door sensor described above, it can be mounted on various modules that operate using the detection result of the presence or absence of an object and the distance to the object.

  More specifically, the module using the detection result of the distance to the object includes, for example, a liquid level meter, a car back sonar, distance measurement, or automatic traffic signal switching. Modules that use the presence or absence of an object include an intruder alarm device and an automatic lighting switch. This is because the distance to the object and the presence / absence of the object can be detected by measuring the reflection time of the ultrasonic wave and observing the vibration frequency (Doppler effect).

Further, the above embodiment is an explanation of the optimum example, and the piezoelectric sensor of the present invention may not be completely communicated from the upper opening 72 to the lower end 74 as long as the base 42 and the peripheral wall 70 are integrated. . This is because if the hole corresponding to the horn window 78 described above is formed in the peripheral wall 70, the lead wires 16 and 26 can be drawn from the vibrator 2 to the outer peripheral side of the peripheral wall 70. Further, it is sufficient that at least one hole corresponding to the horn window 78 is provided in the peripheral wall 70. This is because both of these lead wires 16 and 26 may be pulled out from the same hole.
In any of these cases, similarly to the above, there is an effect that the manufacturing cost of the piezoelectric sensor can be reduced and the assembly can be facilitated.

1 Piezoelectric sensor 2 Unimorph vibrator (vibrator)
10 Piezoelectric ceramics (piezoelectric material)
16, 26 Lead wire (conductive wire)
20 Diaphragm 30 Horn (Equalizer)
40 Case 42 Base 44 Upper surface 54 Lower surface 58, 60 Spacer (Space rib)
62 pins (protrusions for polarity identification)
64 Protection part (conductive wire holding hole)
70 Perimeter wall 76 Conductive wire receiving opening (side opening)
78 Horn window (window)
80, 82 terminals

Claims (5)

A piezoelectric body;
A diaphragm that forms a vibrator capable of transmitting or receiving ultrasonic waves in combination with the piezoelectric body;
A conductive wire that is led out from the vibrator and electrically connects the vibrator and a terminal connected to the circuit board;
A pedestal that supports the vibrator on a surface opposite to a surface that holds the terminal, and a peripheral wall that is erected along the periphery of the pedestal and surrounds the vibrator. A case with an integrally formed peripheral wall ;
An equalizer mounted on the vibrator and amplifying the ultrasonic wave;
The inner peripheral side and the outer peripheral side of the peripheral wall communicate with each other, the arrangement state of the vibrator with respect to the pedestal, the arrangement state of the conductive wire with respect to the vibrator, or the placement of the equalizer with respect to the vibrator A piezoelectric sensor having a window portion whose state can be visually recognized. The piezoelectric sensor according to claim 1,
The peripheral wall includes a side opening whose inner peripheral side and the outer peripheral side are in complete communication over the height direction of the case, and receives the conductive wire drawn from the vibrator and guides it to the terminal. A piezoelectric sensor. The piezoelectric sensor according to claim 1 or 2,
The pedestal includes a conductive wire holding hole that penetrates the height direction of the case and communicates with the side opening and holds the conductive wire received by the side opening. Sensor. The piezoelectric sensor according to any one of claims 1 to 3 ,
The piezoelectric sensor according to claim 1, wherein a space for securing a space between the surface and the circuit board is provided on a surface for holding the terminal. The piezoelectric sensor according to any one of claims 1 to 4 ,
A piezoelectric sensor, wherein a surface for holding the terminal is provided with a polarity identification protrusion for identifying the polarity of the terminal.

Images