JPH0613300U - Ultrasonic sensor - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an ultrasonic sensor capable of short-distance detection. [Structure] An ultrasonic sensor in which a material having an acoustic impedance different from that of the acoustic matching layer is applied or adhered to the side surface of the acoustic matching layer and the side surface of the case. [Effect] The generation of unnecessary vibration at the end of the acoustic matching layer is suppressed. It is possible to obtain an ultrasonic sensor with good reverberation, which is relaxed and absorbed without affecting sensitivity.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an ultrasonic sensor.

[0002]

[Prior art]

 An ultrasonic sensor that emits ultrasonic waves in the radial vibration mode or the thickness vibration mode of a ceramic or magnetostrictive transducer, as shown in FIG. 5, has an acoustic matching layer placed as an intermediate medium on the ceramic or magnetostrictive transducer. Is known as the general one.

The acoustic impedance of the ceramic or magnetostrictive transducer has an order of magnitude higher than that of air, and it is necessary to match the acoustic impedance between the transducer and air in order to enhance the sound radiation effect. There is.

However, this structure has a drawback that unnecessary vibration occurs at the end of the matching layer, which adversely affects reverberation and makes it impossible to detect a short distance.

[0005]

[Problems to be solved by the device]

 The ultrasonic sensor with the conventional structure has a problem that unnecessary vibration is generated at the end of the matching layer, which adversely affects reverberation. Further, there is a problem that the mechanical strength of the end portion is weak and a defective product may be generated due to chipping or cracking. An object of the present invention is to provide an ultrasonic sensor that solves the conventional problems and contributes to the improvement of reverberation.

[0006]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention is an ultrasonic sensor in which an acoustic matching layer is mounted on a ceramic or magnetostrictive transducer, and the acoustic matching layer is formed on the side surface of the air radiation surface of the acoustic matching layer. It is characterized by bonding substances with different acoustic impedances.

[0007]

[Action]

 According to the above configuration, by bonding a substance having an acoustic impedance different from that of the acoustic matching layer to the side surface of the aerial radiation surface of the acoustic matching layer, unnecessary vibration is generated at the end of the acoustic matching layer due to interference. An ultrasonic sensor with good reverberation can be obtained by suppressing, mitigating, and absorbing.

[0008]

【Example】

 Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 is a side sectional view of an ultrasonic sensor as a first embodiment of the present invention, which shows a piezoelectric element, an acoustic matching layer mounted on the piezoelectric element, a case having the piezoelectric element therein, and the piezoelectric element. It consists of a pair of lead wires connected to the electrode terminals and a terminal board. The acoustic matching layer has a thickness T corresponding to a quarter wavelength (corresponding to the resonance frequency) in the material or an odd multiple of a quarter wavelength. Furthermore, by applying or adhering a polymer elastic resin having an acoustic impedance different from that of the acoustic matching layer to the side surface of the aerial radiation surface of the acoustic matching layer and the side surface of the case, unnecessary vibration is alleviated by interference, Configured to be absorbed. FIG. 5C is a diagram showing the reverberation characteristic of this embodiment. It was confirmed that the reverberation time was 523 μSec, enabling short-distance detection compared to the conventional product (768 μSec). As a second embodiment of the present invention, FIG. 2 shows that the same results as in the previous embodiment can be obtained by using tapes on the side of the aerial radiation surface of the acoustic matching layer and the side of the case. In FIG. 3, as a third embodiment of the present invention, the same results as in the previous embodiment could be obtained by using heat-shrinking tubes on the side of the air radiation surface of the acoustic matching layer and the side of the case. FIG. 4 shows a further embodiment of the present invention by using a material having an acoustic impedance different from that of the above acoustic matching layer on the peripheral portion and side surface of the aerial radiation surface of the acoustic matching layer and the side surface of the case. We were able to obtain a product with a short reverberation time.

[0009]

[Effect of device]

 As described in detail above, the present invention is an ultrasonic sensor in which an acoustic matching layer is mounted on a ceramic or magnetostrictive transducer, and the acoustic matching layer is formed on the side of the air radiating surface of the acoustic matching layer and the side of the case. By applying or adhering different substances, it is possible to obtain and obtain an ultrasonic sensor with good reverberation without suppressing and absorbing the generation of unnecessary vibration at the end of the acoustic matching layer, absorbing it, and affecting sensitivity. I can. In addition, it is possible to prevent damage such as cracks and cracks at the ends of the acoustic matching layer, which cause defective products.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

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

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

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

5A, 5B, and 5C are diagrams comparing reverberations when a conventional ultrasonic sensor and an example are driven by a tone burst wave.

FIG. 6 is a sectional view of a conventional ultrasonic sensor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukio Haneda 4 372 Kumoyama, Tottori City, Tottori Prefecture Japan Ceramics Co., Ltd.

Claims (4)

[Scope of utility model registration request] 1. An ultrasonic sensor in which an acoustic matching layer is mounted on a ceramic or magnetostrictive transducer, and the acoustic matching layer has acoustic impedances different from those of the acoustic matching layer on the side surface of the aerial radiation surface and the side surface of the case. An ultrasonic sensor characterized by applying or adhering a substance. 2. The ultrasonic sensor according to claim 1, wherein a tape is used on a side surface of the aerial radiation surface of the acoustic matching layer and a side surface of the case. 3. The ultrasonic sensor according to claim 1, wherein a heat-shrinkable tube is used on the side surface of the aerial radiation surface of the acoustic matching layer and the side surface of the case. 4. The ultrasonic sensor according to any one of claims 1, 2, and 3, wherein a substance having an acoustic impedance different from that of the acoustic matching layer is applied or adhered to a part of an aerial radiation surface of the acoustic matching layer. And ultrasonic sensor.