JPH01270499A - Ultrasonic element - Google Patents

Abstract

PURPOSE:To drastically enhance sensitivity by forming independent transmitting part and a receiving part on a diaphragm, and preventing the effect of a reverberant signal generated according to transmission from being exercised on the receiving part. CONSTITUTION:A common electrode 12 is provided on one side of a diaphragm 11 consisting of piezoelectric materials. A transmitting electrode 13 and a receiving electrode 14 are provided on the other side. The respective independent transmitting part and receiving part are formed by the electrodes 13 and 14. Thus, the effect of the reverberant signal on the receiving part due to the transmission is prevented, and the sensitivity is greatly enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an ultrasonic element that transmits and receives ultrasonic waves using one element.

[Conventional technology] Conventional 8 For example, as an obstacle detection device for a vehicle.

The best configuration is one that transmits ultrasonic pulses from an ultrasonic transmitter, receives reflected waves from the object to be detected or obstacles by an ultrasonic receiver, processes this received signal, and issues an alarm. It is true. In order to widen the detection range or directivity of the obstacles, various inventions have been proposed (for example, JP-A-57-40665 and JP-A-57-182666).

(See Publication No. 59-154380). - In order to make sumo wrestler record detection devices smaller or more compact, devices that double as transmitters and receivers are also used, and in consideration of outdoor use, sealed or shielded devices are also used. Some have a drop-shaped configuration.

FIG. 6 (a+ is a cross-sectional view of the main part showing an example of a conventional ultrasonic transmitter/receiver. In the same figure, l is a case, and the closed end is formed into a truncated conical shape by, for example, an aluminum alloy. , an open end is provided at the other end.A vibrator 2 made of a piezoelectric material is integrally fixed inside the closed end of the case 1, and a terminal plate 3 is attached to the open end to form a sealed structure. 4 is a terminal.

It is fixed so as to penetrate inside and outside the terminal plate 3, and is electrically connected to the vibrator 2 and the case l through the green lead 5, respectively.

Next, FIG. 6 (bl is an enlarged vertical cross-sectional view of the vibrator 2 in FIG. 6 ta+. In FIG. 6 fbl, 2a is a diaphragm 9 made of, for example, lead zirconate titanate (PZ)). Then, two coats 2b made of a conductive material such as granite are coated or fixed on both the upper and lower surfaces.

With the above configuration, as shown in FIG.
Terminal 4! When this signal voltage is applied, the vibrator 2 performs flexural vibration and transmits ultrasonic waves into the air from the closed end surface 1a of the case 1. Conversely, when an ultrasonic wave is incident on the closed end surface 1a, the vibrator 2 fixed to the closed end surface 1a is excited to perform flexural vibration, and a signal voltage is generated at the terminal 4 via the electrode 2b. Therefore, obstacles can be detected as described above.

[Problem to be solved by the invention]

The ultrasonic transceiver with the above configuration transmits and receives ultrasonic waves (3) using one vibrator 2. For example, when the distance to an obstacle is short, a reverberant signal exists near the transmitted signal. Therefore, there is a problem in that it couples with the received signal, making detection difficult.

On the other hand, if the reverberation signal is made smaller, there is a disadvantage that the sensitivity of the vibrator 2 is significantly reduced. In addition, when the sensitivity is improved, surrounding noise is also picked up, and the residual g signal increases. In this way, the conventional transducer 2 or ultrasonic element uses the same vibration means for transmission and reception, so there is a problem in that it is not possible to simultaneously improve the contradictory characteristics of removing reverberant signals and improving sensitivity. .

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems existing in the above-mentioned conventional techniques and provide an ultrasonic element that can remove reverberant signals and has high sensitivity.

(Means for Solving the Problems) In the invention No. 91, a common electrode is provided on one side of a diaphragm made of a piezoelectric material, and a common electrode is provided on the other side for transmission and reception. electrodes are provided to form three independent transmitting sections and a receiving section. A technical method was adopted.

In the above configuration, it is effective to configure one electrode for transmitting and one electrode for receiving to be separated through a gap.

Furthermore, it is even more effective to configure the transmitting section and the receiving section, including the diaphragm, separated by a gap.

Furthermore, if the transmitting section and the receiving section are separated with a gap including the common electrode, even more effects can be expected.

In the configuration of the first invention, a transmitting or receiving electrode is sandwiched between two diaphragms made of material t4 having the same piezoelectric properties, and an electrode other than the above electrode is placed on the other side. It may be provided.

Furthermore, in the configuration of the fourth or fifth invention, it is effective to form the thicknesses of the diaphragms constituting the transmitting section and the receiving section to different dimensions in order to optimize the characteristics of the transmitting section and the receiving section. .

[For production]

With the above configuration, it is possible to set the circuit constants of the transmitting section and the receiving section separately, and even though it is an ultrasonic element for both transmitting and receiving purposes, it exhibits functions with all 1 characteristics. be able to.

[Actual example]

Fig. 1 ta + (bl does not indicate the first embodiment of the present invention; 1 is made of lead zirconate titanate (PZT) to have a diameter of 8 mm and a thickness of Q of 2 mm.

12 is common Ijl! It is an electrode and is made of a conductive material.

It is fixed to one surface of the diaphragm 11. Next, 13° and 14 are a transmitting electrode and a receiving mold) beads, respectively.

It is formed of a conductive material t1 and is attached to the other surface of the diaphragm 11. Note that the transmitting electrode 13 and the receiving electrode 14 are separated through a ring-shaped gap 15 to form eight independent transmitting sections and eight receiving sections. In the above configuration, the thickness of each electrode tffi 12.13°1.4 is set to, for example, 10 μm, and one gap is set to 0.1 to Q, 2 mm.

After configuring as described above, the common electric power 12 side is connected to the sixth
It is fixed to the inside of the closed end of the case 1 as shown in FIG.

With the above configuration, the transmitting electrode 13 and the receiving electrode 14 form an independent transmitting section and a receiving section, respectively, so that the receiving section can be affected by the reverberation signal caused by the transmission.

Figure 2 fal (bl is a longitudinal sectional view and a plan view showing the second embodiment of the present invention, respectively, and the same parts are the
2I(al (indicated by the same reference numerals as bl. Fig. 2f)
at (b) The transmitting amount I!l 113 is formed by a disk portion 13a, a ring portion 13b, and a connecting portion 13C that connects the two, and the receiving electrode 14 is formed in a ring shape with a portion cut out. A disk portion 13a and a ring portion 13b which constitute a transmission dose 1M13 are separated through a gap 15.
The three functions are the same as in the first embodiment.

FIG. 3 (al (bl) is a longitudinal sectional view and a plan view showing a third embodiment of the present invention, respectively, and the same parts are designated by the same reference numerals as in the figures showing the previous embodiment.
, 16 is a ring-shaped groove, and the feeding (ε electrode 1
3 and the receiving electrode 14.

It is bored into the diaphragm 11 and leaves some connection parts 16a between it and the common electrode 12. The thickness δ5 of this connection portion is, for example, 0.1 to 0.15 mm.

With the above configuration, the independence of the transmitting section and the receiving section formed by the transmitting electrode 13 and the receiving electrode 14 is greatly increased, and the influence Ig of the reverberant signal due to transmission is further reduced, and the sensitivity is We can expect improvement.

Fig. 4 fal (bl is a vertical cross-sectional view and a plan view showing a fourth embodiment of the present invention, respectively, and the same parts are designated by the same reference numerals as in the figures showing the previous embodiment. Fig. 4 ta + [bl
What is shown in Figure 3 is ta+ (781 in bl).
6.

It extends to the common electrode 12. With this configuration, the common electrode 12 is separated into the disk part 12a corresponding to the transmitting electrode 13 and the ring part 12b corresponding to the receiving electrode 14, so that the transmitting part and the receiving part are completely separated. Since they become separate and independent, further removal of reverberant signals and improvement in sensitivity can be expected. Further, the thickness of the diaphragm 11 constituting the transmitting section and the receiving section can be set independently.

This allows the transmission and reception functions to be optimized.

FIG. 5 is a longitudinal sectional view showing a fifth embodiment of the present invention, and the same parts are designated by the same reference numerals as in the figures showing the previous embodiment. In FIG. 5, lla and 11b are a transmitting diaphragm and a receiving diaphragm, respectively.

For example, while being fixed via the transmitting electrode 13.

A 1iTl electrode 12 and a receiving lamp 14 are fixed to the surfaces of the transmitting diaphragm 11a and the receiving diaphragm 11b, respectively.

With the configuration described below, the transmitting diaphragm 11a and the receiving diaphragm 1 are
There is an advantage that the thickness of 1b can be freely selected and R circuit constants can be selected for transmission and reception.

In this example, several examples of the arrangement of the transmitting dose) and the receiving electrode are shown, but the effect is the same even if the arrangement of both is reversed, and the materials and dimensions of the electrode and the shaking plate are as follows: J should be selected by the government in 2 based on the intended use and other considerations. Furthermore, the shape of the electrode can be freely selected from the disk shape and ring shape shown in this embodiment, to the five-piece shape, and other shapes.

〔Effect of the invention〕

Since the present invention has the structure and operation as described above, the following effects can be expected.

(1) Since an independent transmitter and receiver are formed on the diaphragm, the influence of reverberant signals generated during transmission on the receiver is completely eliminated or the shape is significantly reduced. can significantly improve sensitivity.

(2) The diaphragms corresponding to the transmitting section and the receiving section can be formed to have different thicknesses, and the optimum circuit constants for transmitting and receiving can be selected, and sensitivity can be greatly improved.

[Brief explanation of the drawing]

1 to 4 show a first embodiment and a first embodiment of the present invention, respectively.
51 is a vertical sectional view showing the fifth embodiment of the present invention, and FIG. 6 fa+ is a conventional ultrasonic transmitting and receiving device. FIG. 6 is a vertical sectional view of the main parts showing an example of the three devices (BL is an enlarged vertical sectional view of the vibrator in FIG. 6+a+. 11: diaphragm, 12: common electrode, 13: transmission mold filter, 1
4: receiving electrode, 15 two gaps, 16: groove.

Claims (6)

[Claims] (1) A common electrode is provided on one side of a diaphragm made of piezoelectric material, and transmitting and receiving electrodes are provided on the other side,
An ultrasonic element characterized in that a transmitting section and a receiving section are each formed independently. (2) The ultrasonic element according to claim 1, wherein the transmitting electrode and the receiving electrode are separated through a gap. (3) The ultrasonic element according to claim 2, wherein the diaphragm is separated through a gap. (4) The ultrasonic element according to claim 3, wherein the common electrodes are separated through a gap. (5) In addition to sandwiching a transmitting or receiving electrode between two diaphragms made of materials having the same piezoelectric characteristics,
2. The ultrasonic element according to claim 1, further comprising an electrode other than said electrode on the other side. (6) The ultrasonic element according to claim 4 or 5, wherein the diaphragms constituting the transmitting section and the receiving section are formed to have different thicknesses.