JPS5830386Y2 - Ultrasonic transducer - Google Patents

Description

[Detailed description of the invention] The present invention relates to the improvement of an ultrasonic transducer for transmitting or receiving ultrasonic signals suitable for use in remote control devices of television receivers, alarms, etc. ,
The present invention relates to a transducer having a relatively high center frequency and achieving high transmitting and receiving sensitivity over a wide frequency band.

This type of ultrasonic transducer is equipped with an aluminum watering can-shaped additional resonator (hereinafter referred to as a watering can resonator) or a resin-made additional resonator with a trapezoidal cross section (hereinafter referred to as a trapezoidal resonator) in the center of a ceramic bimorph transducer. ) is known.

The former, which uses an aluminum watering can resonator, is
The interval between the frequency point where the second sensitivity (main sensitivity) occurs and the frequency point where the second sensitivity (subsensitivity) occurs, although it is small, is very wide, and it can be used practically in the frequency range in between. Since little sensitivity is obtained, it is extremely difficult to obtain large sensitivity over a wide frequency band.

On the other hand, the latter transducer equipped with a resin trapezoidal resonator has a structure as shown in FIG.

In FIG. 1, reference numeral 1 denotes a composite resonator, which is constructed by fixing a resin trapezoidal resonator 3 near the center of one side of a ceramic bimorph resonator 2.

This composite vibrator 1 is fixed on a substrate 4 with a support member 5 formed integrally with the substrate 4 interposed between the substrate 4 and the bimorph vibrator 2.

6 is a shield plate, and 7 is an external case.

When viewed from the impedance characteristics shown in Figure 4a, such a transducer has a first resonance in the low frequency range where the first sensitivity should occur, and a second resonance in the high frequency range where the second sensitivity should occur. Excite resonance.

However, as is clear from Figure 4, the level of the first sensitivity that should be generated in response to the first resonance is very low, and with such a low level of sensitivity, it is impossible to transmit and receive ultrasound in this band. Have difficulty.

Therefore, this type of transducer can only obtain narrowband characteristics only in the low frequency region where the second sensitivity occurs.

If the practically usable sensitivity level is around 73 dB (indicated by A), waves can be transmitted and received only in a narrow frequency range shown by B.

The reason why the level of the first sensitivity becomes low in this way is presumed to be due to the following reason.

In other words, according to the results of an experiment in which powder was placed on the additional resonator 3, which serves as the ultrasonic wave transmitting/receiving surface, and the first resonance and second resonance were excited respectively, the first resonance was caused by the powder vibrating vertically over the entire surface. It is thought that this is causing blow-up vibration, and the second resonance is thought to be caused by bending vibration because the powder concentrates on the node line.And since the composite vibrator 1 is fixed to the substrate 4, blow-up vibration is caused. It can be estimated that the vibration due to the mode is suppressed and the first sensitivity becomes a low level.

Therefore, the present invention is concerned about the fact that the first sensitivity is caused by the vibration caused by the blow-up mode, and has provided a means for smoothing the vibration due to the blow-up mode, and has designed the means to have an extremely simple structure. The purpose of this invention is to provide an ultrasonic transducer with broadband characteristics.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

In FIGS. 2 and 3, reference numeral 10 denotes a composite resonator, which is made up of a square plate-shaped piezoelectric ceramic bimorph resonator 11 and an additional resin resonator 12 fixed to the center of one side with adhesive.

The bimorph resonator 11 is made up of two piezoelectric ceramic plates bonded together, and a lead l is placed near the node line on both outer electrodes.
la and llb are connected by solder.

The additional resonator 12 is composed of a trapezoidal main body 12a having a trapezoidal vertical section and a circular cross section, and a cylindrical projection 12b integrally formed on this main body. The surface is brought into contact with the bimorph resonator 11, and the protrusion 12b
A certain surface functions as an ultrasonic wave transmitting (wave receiving) surface together with the protrusion 12b.

Reference numeral 13 denotes an insulating case with an open end and integrally formed with a support 14 .

The support body 14 is constituted by a cylinder formed inside the case 13 so as to extend in the axial direction from the center of the bottom portion.

A concentric projection 15 having a smaller diameter than the outer diameter of the support 14 is provided on the end surface of the cylindrical support 14 on the case opening side.

The thickness of the peripheral wall 16 of the case 13 is gradually reduced from the bottom toward the opening on the inner peripheral side, and a plurality of steps are provided on the inner peripheral surface of the case.

That is, the inner diameter of the case 13 is largest at the open end and becomes smaller toward the bottom.

The case peripheral wall 16 is provided with a step only near the opening end on the outer peripheral side.

Reference numerals 19 and 20 indicate external lead-out pins, which are implanted in the case peripheral wall 16.

A cutout 17.18 is provided in the case peripheral wall 16 opposite the tip of the pin 19.20 protruding into the case 13.

21 is a split ring-shaped elastic body made of silicone rubber, for example, and is fitted into the protrusion 15 .

The thickness of the elastic body 21 is greater than the height of the protrusion 15, and when the elastic body 21 is fitted into the protrusion 15, a gap is formed between its upper surface and the upper surface of the protrusion 15.

Further, a circumferential wall may be provided around the protrusion 15 on the end surface of the support body 14, and the elastic body 21 may be fitted into a circumferential groove formed between the circumferential wall and the protrusion 15.

It is preferable that the elastic body 21 and the support body 14 be fixed by filling a space between them and the support body 14 with a silicone adhesive.

A composite vibrator 10 is fixed onto the elastic body 21 with a silicone adhesive with its wave transmitting and receiving surface facing the case opening.

To install the vibrator 10, connect the solder connection part of the lead 11b on the bottom side of the bimorph vibrator 11 to the divided part 2 of the elastic body 21.
1 Place it in position a.

It is preferable that the divided portion 21a is sufficiently filled with silicone adhesive to seal the gap between the bimorph resonator 11 and the support 14.

Lead 11 a to pin 19, node 11 b to pin 2
It is preferable that each solder connection portion be soldered and that a silicone adhesive be applied to each solder connection portion.

22 is a shield plate that is brought into contact with the bottom of the case 13, is soldered to one pin 20, and is electrically insulated from the other pin 19.

Reference numeral 23 denotes a mesh window member that covers the opening end of the case, and its periphery extends to the outer step of the case peripheral wall 16.

The metal cover 24 is placed over the case 13 from the case opening and fixed to the case 13 by suitable means, and the window member 23 is fixed by the cover 24 and the case 13.

According to this embodiment, since the composite vibrator 10 is supported via the elastic body 21, the vibration due to the blow-up mode is efficiently generated, and as shown in FIG. May we have a great level of first sensitivity,
In combination with the second sensitivity, which originally has a high level, a transducer with good sensitivity over a wide band can be obtained.

The frequency bandwidth in which sensitivity can be obtained is significantly wider than that of the conventional example, as shown by C in FIG.

Furthermore, since the elastic body 21 only needs to be fitted into the protrusion 15, it can be positioned reliably, and the composite vibrator 10 can be easily attached to a predetermined position.

Moreover, the lead 11b is attached to the divided portion of the ring-shaped elastic body 21.
Since the solder portion is located, the composite vibrator 10 is not tilted by the solder portion, and a predetermined directivity can be reliably obtained.

Furthermore, since the additional resonator 12 is provided with the protrusion 12b,
As the Q of the first resonance increases, the Q of the second resonance decreases. ), the sensitivity corresponding to the low Q second resonance is even greater.

It should be noted that the sensitivity due to the first resonance is not affected by the fluctuation of Q as seen experimentally.

This can be presumed to be because the vibration mode of the first resonance is the blow-up mode.

Furthermore, the sensitivity can be changed by changing the shape of the circumferential groove between the support body 14 and the case circumferential wall 16 or the step shape on the inner circumferential surface of the case circumferential groove 16, so these shapes can be determined based on experiments or calculations. Just set it to the optimal shape.

The present invention is not limited to the above-mentioned embodiments, and it is possible to use a ring-shaped elastic body, an additional resonator without protrusions, or an insulating case of other shapes.

As explained above, the present invention provides a composite vibrator in which a piezoelectric bimors vibrator and an additional resin resonator are fixed, through a ring-shaped or split ring-shaped elastic body fitted into a protrusion of a support. Since it is attached to a support, the vibrations caused by the blow-up mode operate smoothly, and the sensitivity corresponding to the vibrations increases.This, combined with the sensitivity corresponding to the vibrations caused by the bending mode, provides good sensitivity over a wide frequency band. As a result, according to the present invention, it is possible to obtain a wideband transducer, and it also has the advantage that it can be constructed extremely easily because the means for increasing sensitivity over a wideband only requires the use of a ring-shaped or split ring-shaped elastic body. .

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional ultrasonic transducer, and FIGS. 2 and 3 show an embodiment of the ultrasonic transducer according to the present invention.
Figure 2 is a sectional view, Figure 3 a, l), c. d shows the main parts, FIGS. 4a and 4b are a resonance characteristic diagram and a sensitivity characteristic diagram of a conventional example, and FIGS. 5a and b are a resonance characteristic diagram and a sensitivity characteristic diagram of this embodiment. 10...Composite resonator, 11...Bimors oscillator, 12...Additional resonator, 13...
... Insulation case, 14 ... Support body, 15 ...
...Protrusion, 21...Elastic body.

Claims (2)

[Scope of utility model registration request] (1) A composite vibrator with an additional resin resonator provided in the center of the bimorph vibrator, a support body having a protrusion, and a ring-shaped or split ring-shaped elastic body having a thickness greater than the protrusion. . An ultrasonic transducer, characterized in that the elastic body is fitted into the protrusion, and the composite vibrator is adhered onto the elastic body. (2) The ultrasonic transducer according to claim 1, wherein the split portion of the split ring-shaped elastic body is located at a lead wire connection portion to the bimorph vibrator.