JPS6349996Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field The invention relates to an ultrasonic ceramic microphone that transmits and receives ultrasonic waves, and is particularly useful for outdoor parking meters and the rear of automobiles where good pulse response is required. It is applied to detectors.

Conventional Structure and its Problems A conventional ultrasonic ceramic microphone of this type is structured as shown in FIG. That is, a piezoelectric ceramic vibrator 1 is bonded to the inner bottom surface of a cylindrical case 2 having a bottom surface having a truncated conical cross section to constitute a vibrating section 2a, a resonant ring 3 is fixed to the inside of the case 2, and The terminal plate 4 was hermetically fixed to the open end of the case 2 via an elastic adhesive 6. Also, 7a and 7b are lead wires, 8a
and 8b are external terminals implanted in the terminal board 4, and 5 is a metal base fixed to the terminal board 4.

In this case, when vibration occurs in the metal cylindrical case 2 due to electro-mechanical conversion of the piezoelectric ceramic vibrator 1,
Since the case 2 and the resonant ring 3 resonate and are excited by the high vibrations of metal, it exhibits high sensitivity, but on the other hand, damping occurs in response to pulse signals, which tends to cause reverberant vibrations.

Purpose of the invention The present invention aims to eliminate these conventional drawbacks, and to provide an ultrasonic ceramic microphone that alleviates the reverberant vibrations of the case and resonance ring and exhibits steep pulse response. be.

Structure of the Invention In order to achieve this object, the ultrasonic ceramic microphone of the invention has an internal pressure electromagnetic vibrator of the case bonded to the inner bottom surface of a cylindrical case having a truncated conical bottom section; A resonance ring is fixed to the inside of the case, and a vibration isolator is provided in contact with the inside of the slope of the truncated conical bottom of the case, and a terminal plate is sealed at the open end of the case via an elastic adhesive. It is fixed. According to this configuration, by providing the vibration isolator in contact with the inner surface of the cylindrical case, it is possible to improve pulse responsiveness without reducing sensitivity.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. 2. Note that in FIG. 2, the same parts as in FIG. 1 are given the same numbers.

In the figure, a piezoelectric ceramic vibrator 1 is bonded to the inner bottom surface of a cylindrical case 2 having a bottom portion with a truncated conical cross section to form a vibrating case having a vibrating portion 2a integrated with the case 2. The resonance ring 3 fixed inside the case 2 resonates when excited by the vibrating part 2a of the case 2, and has the effect of significantly reducing the vibration of the open end of the case 2, and protects the case 2 from external shocks. While increasing the strength of the system, it also reduces vibration leakage. Reference numeral 9 denotes a vibration isolator having a cushioning effect such as rubber, which is provided in contact with the inside of the slope of the bottom surface of the case 2, and is provided in contact with the inside of the slope of the bottom surface of the case 2.
It is made so that it does not come into contact with a. Since the vibration isolation level of the vibration isolator 9 changes depending on its density and shape, it is designed according to the required performance. For example, although the embodiment has a uniform contact surface that matches the inner surface of the case 2, the contact surface may be wedge-shaped to make a line contact with the inner surface of the case 2, or the vibration isolator 9 may have holes or air holes. It takes a shape that changes the density by forming a ball. That is, it is not limited to the donut shape as shown in the figure.

Effects of the invention The ultrasonic ceramic microphone of the invention is constructed as described above, and by placing them in contact with each other, it is possible to reduce reverberant vibrations in response to pulse signals and provide steep pulse response. . Furthermore, this vibration isolator suppresses higher-order resonance and stabilizes fundamental vibration, making it possible to provide stable frequency characteristics.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a conventional ultrasonic ceramic microphone, and FIG. 2 is a cross-sectional view showing an embodiment of the ultrasonic ceramic microphone according to the present invention. 1... Piezoelectric ceramic vibrator, 2... Cylindrical case, 3
... Resonance ring, 4 ... Terminal board, 6 ... Elastic adhesive, 9 ... Vibration isolator.

Claims (1)

[Scope of utility model registration request] A piezoelectric ceramic vibrator is bonded to the inner bottom surface of a cylindrical case having a bottom portion having a truncated cone shape in cross section, and a resonance ring is provided inside the case and is in contact with the inside of the slope of the bottom portion of the truncated cone shape of the case. An ultrasonic ceramic microphone is provided with a vibration isolator, and a terminal plate is hermetically fixed to the open end of the case via an elastic adhesive.