JPH0445354Y2 - - Google Patents

Description

[Detailed description of the invention] [Purpose of the invention] (Field of industrial application) The present invention is an ultrasonic transformer that generates ultrasonic waves in response to electrical energization or generates electrical signals in response to sound waves. Regarding Yusa.

(Prior technology) An ultrasonic transducer in which a diaphragm is fixed to an electricity/vibration conversion element that converts voltage into mechanical displacement (change in shape or position) and pressure into an electrical value that can be converted into an electrical signal. is publicly known.

FIG. 6 shows an example of a conventional ultrasonic transducer. In this, the inner surface of the cup-shaped metal diaphragm 1 is deformed by the application of a voltage, and is made up of a piezo element that generates a voltage by the application of pressure.
A vibration conversion element 2 is joined with one electrode thereof in contact with the diaphragm 1. One end of an electrical lead 3 is connected to the other electrode of the element 2, and the other end of the electrical lead 3 is connected to a terminal pin 4. One end of an electrical lead 5 is connected to the diaphragm 1, and the other end of the electrical lead 5 is connected to a terminal pin 6.

An O-ring 10 is fitted onto an insulating base 8 whose bottom surface is covered with a metal cap 7 and an O-ring-shaped elastic material 9 is bonded to the upper flange surface, and the opening edge of the diaphragm 1 is engaged with the opening. The diaphragm 1 is integrally fixed to the base 8 by caulking the edges into a ring shape 11.

The elastic material 9 and the O-ring 10 make the space between the diaphragm 1 and the base 8 watertight to prevent dirt and liquid (typically water) from entering, but cannot prevent the diaphragm 1 from vibrating.

When a voltage at an ultrasonic frequency is applied between the terminal pins 4-6, the element 2 expands and contracts in the radial direction at the frequency, thereby changing the diaphragm 1 and generating ultrasonic waves outside the diaphragm 1.

An example of how this type of ultrasonic transducer is used is shown in FIG. 7a. This refers to a vehicle equipped with an ultrasonic transducer in the rear bumper of the vehicle in order to detect the presence or absence of an obstacle at the rear of the vehicle and, if so, the distance to the obstacle. In this example, one transducer emits ultrasonic waves, and one or more other transducers detect reflected ultrasonic waves. Another usage mode is to detect reflected waves using a transducer that emits ultrasonic waves.

A cross section of the ultrasonic sensor base 12 with the transducer mounted is shown in FIG. 7b. The transducer is further fixed to the base 12 via an elastic member 13 so that vibrations of the vehicle body do not affect the transducer.

However, since this type of transducer generally has a weak output, when transmitting the transducer's output signal to a signal processing device installed in a suitable space in the vehicle, it is necessary to avoid induced noise superimposed on the output signal. cannot be ignored. Therefore, conventionally, in order to eliminate the influence of induced noise, an amplifier is placed close to the transducer to amplify the output of the transducer, and the output of the transducer is amplified until the influence of induced noise can be ignored. The configuration was such that the signal was then transmitted to a signal processing device.

(Problem to be solved by the invention) In this type of transducer, the range in which one transducer can detect reflected waves is limited, so when detecting obstacles around the vehicle, multiple transducers are used. Transducers must be used to cover the obstacle detection range around the vehicle. Therefore, in order to expand the obstacle detection range, it is necessary not only to add transducers but also to add amplifiers, which poses problems of complicating the circuit and increasing costs.

Additionally, if the transducer itself is affected by inductive noise, placing an amplifier close to the transducer will amplify the inductive noise along with the output signal, eliminating the effect of inductive noise. There was also the problem that it was not possible.

In addition, as shown in FIG. 6, the protruding length of the diaphragm 1 in the ultrasonic radiation direction is large, and the base 8 is thick to support the elastic seal structure made of the elastic material 9 and the O-ring 10. Since the elastic member 13 is inserted and the terminal pin extends in the ultrasonic emission direction (opposite direction), the thickness of the sensor base 12 that houses the transducer increases, causing it to protrude from the bumper BR. The length is large. Therefore, the transducer is likely to malfunction due to objects hitting the base 12. In the embodiment shown in FIG. 7a, by the time an object hits the base 12, the transducer should detect it and stop the vehicle, but in many cases the object hits the base 12 while the vehicle is stopped. It also gets in the way when you wash your car. In addition, the entire diaphragm 1 must be floating above the base 8 and the base 12, but mud and dirt can easily enter between the inner surface of the storage hole of the base 12 and the outer surface of the diaphragm 1. As a result, the function of the diaphragm 1 deteriorates. Or it becomes dysfunctional. It is difficult to remove mud and dirt, and objects tend to become undetectable.

There is also a mode of use in which the transducer is housed inside the bumper BR so that the bumper BR does not hit an object. Its appearance is shown in FIG. 8a, and its cross section is shown in enlarged view in FIG. 8b. In this usage mode, the sensor base 14 is designed to use the bumper BR for its original purpose (excluding objects and preventing objects from colliding with the vehicle body) and to narrowly limit the direction of ultrasonic waves. is shaped like a horn, and the base is equipped with a transducer. In this case, mud or dirt gets inside the sensor base 14,
It is difficult to remove, and object detection is likely to fail.

Therefore, an object of the present invention is to construct an ultrasonic transducer that is less susceptible to the effects of induced noise and has a small thickness in the ultrasonic oscillation direction (the ultrasonic arrival direction for reception only).

[Structure of the idea]

(Means for Solving the Problems) The means taken to achieve the above object include a vibrating member having a cup-shaped vibrating space surrounding portion and a flat plate portion continuous to the vibrating space surrounding portion, and an inner surface of the vibrating space surrounding portion. An elastic element that has an electric/vibration converting element bonded to the electric/vibration converting element and an electric lead through hole penetrating in the thickness direction, is bonded to the flat plate part of the vibrating member, and substantially closes the vibration space around the electric/vibration converting element. an elastic member bonded to the outer surface of the support substrate; a conductor plate bonded to the outer surface of the elastic member and having one end grounded; and one end having an electrode of an electric/vibration conversion element. and an electrical lead extending outward from the outer surface of the supporting substrate along the supporting substrate through the electrical lead through hole.

(Function) According to the configuration of the present invention, since the conductive plate arranged along the electricity/vibration conversion element and the electric lead is grounded, it is not connected to the electricity/vibration conversion element and the electricity/vibration conversion element. The electrical leads are electrically shielded and are less susceptible to induced noise.

Further, in the transducer having the above configuration, the flat plate portion of the vibrating member is integrally fixed with the support substrate, and the cup-shaped portion vibrates. The support substrate is a rigid body with respect to ultrasonic vibrations, and prevents the ultrasonic vibrations from propagating to areas other than the vibrating member, thereby increasing the ultrasonic generation/reception efficiency.
Compared to the conventional method, the combination of the elastic member 9, O-ring 10, and mounting elastic member 13 is only the elastic member in the present invention, so the thickness in the ultrasonic emission/reception direction is extremely small, making installation easier. Not only is it easier to remove mud and dirt, but also because the vibrating member has a flat plate part that is continuous to the cup-shaped part.

In a preferred embodiment of the present invention, one electrode of the electric/vibration transducer element is connected to the ultrasonic transmitting circuit and/or receiving circuit by connecting the electric lead to the outside as described above, and the other electrode is connected to the ultrasonic transmitting circuit and/or receiving circuit. As in the conventional case, it is brought into contact with a metal diaphragm which is a vibrating member.
This electrode is normally connected to earth (common potential connection). Therefore, rivet holes are drilled in the flat plate portion of the diaphragm, corresponding holes are also drilled in the support substrate, rivets are passed through these holes, and electrical connection tabs are applied to the outer surface of the support substrate and riveted. This electrical connection tab connects to ground either directly or via an electrical lead. If the outer wall of the transducer is grounded by grounding the conductor plate and the diaphragm described above, it becomes even less susceptible to the effects of the same noise. An aluminum plate or the like is bonded to the outer surface of the elastic member in order to facilitate attachment to a required part of the transducer (for example, a bumper) and to increase attachment strength. Use this as a conductor plate and leave it as it is.
or connect to earth via an electrical lead. Further, in order to facilitate the installation work, a fixture is fixed to the conductive plate.

(Example) Fig. 1 shows the appearance of an embodiment of the present invention, and Fig.
The figure and Fig. 4 show its - line cross section and -
A line cross section is shown, and FIG. 3 shows the appearance of the components before assembly. The diaphragm 1 is a rectangular thin aluminum plate,
An asymmetrical frustum-shaped cup-shaped portion is formed by pressing to protrude from the flat plate portion. A disk-shaped piezo element 2, ie, an electric/vibration conversion element, is bonded to the inner surface of the most protruding part of this cup-shaped part, and an electrode on the surface thereof is in contact with the diaphragm 1. One end of the electrical lead 3 is connected to the other electrode.

On the long side of the flat plate part of the diaphragm 1, there is a 90 degree fold 1.
a, 1b are formed, and the surface of a steel plate 15, that is, a supporting substrate with low elasticity that acts as a rigid body and blocks vibrations of the diaphragm 1, is bonded to the flat plate part, and the folded part 1a is , iron plate 15 on 1b
The sides of the long sides are joined. This iron plate 15 closes the cup-shaped inner space of the diaphragm 1. This iron plate 15 has a lead extraction hole 22 that passes through it in the thickness direction, and the electrical lead 3 passes through this hole 22 and is pulled out along the iron plate 15 to its outer end (short side). There is.

In addition, holes are made in the flat plate part of the diaphragm 1 and the edge of the other short side of the iron plate 15, through which the rivets 16 are passed. A tab 17 is joined and fixed to the iron plate 15. Since the diaphragm 1 is a metal plate (aluminum thin plate) and is a conductor, and the rivet 16 and the iron plate 15 are also conductors, the tab 17 passes through the rivet 16 and the diaphragm 1, and also connects the iron plate 15 and the diaphragm. 1 and is electrically connected to one electrode of the piezo element 2.

On the back side of the surface of the iron plate 15 facing the piezo element 2, there is a foamed rigid resin plate 18 made of a material with high elasticity, high vibration absorption effect (vibration from the transducer support part), and many air holes. It is joined.
A thin aluminum plate 19 is bonded to the resin plate 18 as the bottom plate of the transducer, and a permanent magnet plate (in this example, the short side one of them is N
and the other polarized to S) 20 are joined.

The thin aluminum plate 19 has a hole at its edge for passing a rivet 24 through, and the electric terminal tab 23 is joined and fixed to the thin aluminum plate 19 by caulking the rivet 24.

The outer surfaces of both short sides of the diaphragm 1, the iron plate 15, the resin plate 18, the thin aluminum plate 19, and the permanent magnet plate 20, as well as the outer surfaces of both long sides, are made of flexible molded resin 21a for electrical terminal sealing. 21b and 21
c, covered with 21d.

This transducer (Figures 1 and 2)
The assembly will be explained with reference to FIG. 3.The iron plate 15 is joined to the diaphragm 1 to which the piezo element 2 is fixed, and at this time, the electric lead 3 connected to the piezo element 2 is passed through the hole 22 of the iron plate 15. After the diaphragm 1 and the iron plate 15 are integrated, a tab 17 is fixed to the back surface of the iron plate 15 with a rivet 16. Next, the aluminum plate 19 to which the tabs 23 are fixed in advance with rivets 24 and the resin plate 18 to which the permanent magnets 20 are bonded are bonded to the back surface of the iron plate 15. Then, the side end surfaces of the short sides are covered with mold resins 21a and 21b.

The transducer described above has a bumper with a resin body bonded to the front side of an iron frame, and the transducer mounting hole EH (Fig. 2) is made in the resin body.
Insert into. This insertion joins the transducer's permanent magnet to the bumper's iron frame. Electrical leads (not shown) connected to tabs 17 and electrical leads 3 are routed to the back side of the bumper through holes through the iron frame. Even if mud or dirt gets into the mounting hole, it is easy to remove it because there is a space between the cup-shaped part and the mounting EH that corresponds to the flat plate part.

Note that the permanent magnet 20 is for simple fixing and may be omitted depending on the application. Permanent magnet 2
0 and when the permanent magnet 20 is omitted, the resin plate 18 blocks vibrations from the transducer mounting side (for example, a bumper) to the transducer. Further, the vibration space communicates with the lead passage groove of the resin plate 18 through the lead passage hole 22, and the resin plate 18 absorbs the vibration pressure of the diaphragm 1, substantially preventing the propagation of ultrasonic vibration to the aluminum plate 19. Cut off. The cup-shaped portion of the diaphragm 1 vibrates, and the flat plate portion does not vibrate because it is joined to the iron plate 15. That is, the vibration of the diaphragm 1 is reflected by the iron plate 15 and is not propagated to the resin plate 18, so that the attenuation is small. This contributes to making the transducer thinner without deteriorating the electrical/inductive conversion efficiency of the diaphragm 1.

Further, the electrical terminal tab 23 bonded and fixed to the aluminum plate 19 is grounded to the vehicle body using an electrical lead (not shown), and the electrical terminal tab 17 similarly connected to the diaphragm 1 is also grounded (not shown). It is grounded to the vehicle body using an electrical lead. Aluminum plate 19
By grounding the diaphragm 1 and the outer wall of the transducer, the inside of the transducer is electrically shielded. 2 and electrical leads 3 are less susceptible to induced noise.

Further, as shown in FIG. 4, since the cup-shaped portion of the diaphragm 1 is vertically asymmetrical, the direction of the transmitted ultrasonic wave is directed from a line perpendicular to the tip surface of the diaphragm 1.
The direction out of the way, in this embodiment, is the upward direction. In this way, by making the shape of the cup-shaped part asymmetrical, the directing direction of the ultrasonic waves can be determined arbitrarily.

A specific example of the shape of the transducer of the present invention described above is as follows.

XW (long side length): 28mm YW (short side length): 25mm Thickness of diaphragm 1: 0.8mm Cup height PH: 2mm Element 2 mounting surface (most protruding surface): 12mm x 12mm Bottom of cup-shaped part: long side 22mm x short side 19mm UT: 5mm DT: 2mm (vertically asymmetric, horizontally symmetrical) Iron plate 15 thickness: 1.6mm Resin plate 18 (urethane) thickness: 2mm Aluminum plate 19 thickness: 0.8mm Permanent magnet plate 20 thickness: 2mm Resin plate 18 Height from bottom to top (sound wave emitting end): 6.4mm Height from bottom (lower surface of permanent magnet plate 20) to top (sound wave emitting end): 9.2mm.

Figures 5a and 5b show a modified embodiment of the invention.

This is an example in which two transducers having exactly the same structure are arranged on one conductive plate 19. A pair of diaphragms 1 and 1' are both processed to have the same dimensions, and are formed by press-forming rectangular thin aluminum plates so that an asymmetrical frustum-shaped cup-shaped portion protrudes from a flat plate portion. Inside this cup-shaped part,
Although not shown, as an electric/vibration conversion element,
Piezo elements with uniform characteristics are arranged, and one electrode on the surface of the piezo element is connected to the diaphragm 1 and the 1' rivet 16 and 1, respectively.
6' to electrical terminal tabs 17 and 17'. One ends of electrical leads 3 and 3' are connected to the other electrode on the surface of the piezo element.

Iron plates 15 and 15' are joined to the diaphragms 1 and 1' as support substrates, and the iron plates 1
5 and 15' are provided with through holes for passing the rivets 16 and 16' and for passing the electrical leads 3 and 3'. On the side of the iron plates 15 and 15' facing the diaphragm 1, there is a foamed synthetic resin plate 18 made of a material with a high vibration absorption effect and many air holes.
It is joined as a common member to each transducer so as to cover the end faces of the diaphragms 1, 1' and the iron plates 15, 15'. This foamed synthetic resin board 18
A thin aluminum plate 19 is bonded to one side of the transducer as a common bottom plate for each transducer.
The thin aluminum plate 19 has a hole at its edge for passing a rivet 24 through, and the electric terminal tab 23 is joined and fixed to the thin aluminum plate 19 by caulking the rivet 24. On the surface of the aluminum thin plate 19 facing the foamed synthetic resin plate 18, there is a relatively flexible permanent magnet plate 2 for easy installation.
0 is joined. In addition, the foamed synthetic resin plate 18
A metal fixing plate 25 is bonded to the surface facing the thin aluminum plate.

The above-described transducer is inserted into the transducer mounting hole EH formed in the resin body of the bumper BR, which has a resin body joined to the front side of the iron frame. This insertion joins the transducer's permanent magnet to the bumper's iron frame. Electrical leads (not shown) connected to tabs 17 and electrical leads 3 are routed to the back side of the bumper through holes through the iron frame. As a result, the leads are electrically shielded by the iron frame of the bumper BR. In addition, the tab 2 connected to the thin aluminum plate 19
3 is connected to the vehicle body by an electric lead (not shown).
Preferably grounded to the iron frame of the bumper BR.

In this embodiment, since the installation conditions for a set of transducers can be made the same, complicated adjustment of the signal processing device can be simplified. Also,
By enlarging the fixing plate 25 to cover the transducer mounting hole EH, it is possible to prevent mud and dirt from entering the mounting hole. Furthermore, if the fixed plate 25 is also grounded, it is possible to further reduce the influence of induced noise.

Although this embodiment shows an example in which two transducers are arranged on a common foamed resin board 18, the number of transducers arranged does not need to be two. Further, although an example has been shown in which the characteristics of the transducers to be installed are made the same, it is not necessary to make the characteristics of the placed transducers the same.

FIG. 9 shows the results of an experiment conducted to confirm the effect of grounding the back metal plate.

When the thin aluminum plate 19 is grounded, after the transducer emits an ultrasonic pulse toward the object to be measured at point t = 0, the reflected wave from the object to be measured reaches t.
=t Detected at _one point. Generally, in the method of measuring the distance to the object to be measured using reflected waves of ultrasonic waves, the receiving sensitivity increases as time elapses from the emission of ultrasonic pulses (t = 0), so aluminum If the thin plate 19 was not grounded, the receiving sensitivity would increase and the induced noise would also be amplified, making it impossible to identify the reflected waves from the object to be measured.

[Effect of idea]

As described above, in the present invention, a supporting substrate with low elasticity is bonded to a vibrating member having a cup-shaped protruding vibrating space surrounding portion and a continuous flat plate portion, and the electrical leads are drawn out to the side along the supporting substrate. Since the transducer is an object, its height in the ultrasonic emission direction is low, and even when the transducer is attached to an object, the electric terminal extends in the side surface direction, so the mounting height in the ultrasonic emission direction is small. Therefore, in a usage mode in which the ultrasonic emission surface of the transducer is exposed to the outside air, there is a low possibility that objects will collide with the transducer, and the risk of damage to the transducer is correspondingly low. In addition, for example, when a transducer is installed inside the opening EH as shown in Figure 2, a flat plate is placed around the cup-shaped part, and a relatively wide space is created between the cup-shaped part and the opening EH. Therefore, even if mud or dirt enters the opening EH, it can be easily removed.

Furthermore, since the electric/vibration conversion element and the conductive plate placed along the electric lead are grounded,
The electrical/vibration conversion element within the transducer and the electrical leads connected to the electrical/vibration conversion element are electrically shielded and are less susceptible to induced noise outside the transducer.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the appearance of an embodiment of the present invention, FIG. 2 is a sectional view taken along the line -- in FIG. 1, and FIG. 3 is an exploded perspective view of the ultrasonic transducer shown in FIG. FIG. 4 is a sectional view taken along the - line in FIG. 1. Figure 5a is a perspective view of a vehicle equipped with an ultrasonic transducer according to another embodiment of the present invention;
The figure is a cross-sectional view of the alternative embodiment of the ultrasonic transducer shown in Figure 5a. FIG. 6 is a vertical cross-sectional view of one of the conventional ultrasonic transducers;
Figure a is a perspective view showing a vehicle equipped with this transducer, and Figure 7b is a cross-sectional view of the sensor base 12 shown in Figure 7a. FIG. 8a is a perspective view showing another vehicle equipped with the ultrasonic transducer shown in FIG. 6, and FIG. 8b is a cross-sectional view of the sensor base 14 shown in FIG. 8a. FIG. 9 is a diagram showing reflected waveforms measured using the ultrasonic transducer according to the present invention. 1, 1'... diaphragm (vibrating member), 2... piezo element (electricity/vibration conversion element), 3, 5... electrical lead, 4, 6... terminal pin, 7... metal cap, 8... ... Base, 9 ... Elastic material, 10 ... O-ring, 11 ... Caulking ring groove, 12, 14 ... Sensor base, BR ... Bumper, 13 ... Elastic material, 15, 15' ... Steel plate ( support substrate with low elasticity), 16, 16', 24... rivets, 17, 1
7', 23...Terminal tab, 18...Resin plate (elastic member), 19...Aluminum plate (conductor plate), 20...
Permanent magnet, 21a, 21b...Mold resin, 2
2...Electric lead through hole, 25...Fixing plate.

Claims (1)

[Claims for Utility Model Registration] A vibrating member having a cup-shaped vibrating space surrounding portion and a flat plate portion continuous to the vibrating space surrounding portion;
Vibration conversion element; Has an electrical lead through hole that penetrates in the thickness direction,
a support substrate with low elasticity that is bonded to the flat plate portion of the vibration member and substantially closes a vibration space around the electricity/vibration conversion element; an elastic member bonded to the outer surface of the support substrate; a conductive plate bonded to the outer surface and grounded at one end; and, one end connected to the electrode of the electricity/vibration conversion element, passing through the electrical lead through hole and extending along the supporting substrate to the outside of the supporting substrate. An ultrasonic transducer comprising electrical leads extending outwardly from the side.