JPH0141265Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic microphone used as a wave transmitting device that emits ultrasonic waves into the air and as a wave receiving device that responds to the ultrasonic waves.

This type of ultrasonic microphone consists of a cylindrical metal case with a bottom, in which a thin piezoelectric element with metalized electrode surfaces formed on both main surfaces is attached to the inner bottom surface, and an insulating substrate with a pair of terminal legs embedded therein. one (first) of the piezoelectric elements sealed to and exposed facing the insulating substrate;
The electrode surface of the piezoelectric element is directly bonded to the inner bottom surface of the metal case, and the other (second) electrode surface of the piezoelectric element is bonded to the metal case. Although it is bonded to a pair of terminal legs of the substrate, there is a difficulty in insulating the first lead wire that connects the first electrode surface of the piezoelectric element facing the above-mentioned insulating substrate and the first terminal leg of the insulating substrate. It was hot.

That is, the second electrode surface of the piezoelectric element on the side joined to the metal case and the second terminal leg of the insulating substrate are
When connecting with a lead wire of
The lead wires can be connected by brazing, etc., so there is no risk of shorting with other parts even if there is some slack in the lead wires when brazing, but the piezoelectric on the side facing the insulating substrate The first lead wire that joins the first electrode surface of the element and the first terminal leg of the insulating substrate is significantly longer than the second lead wire because the distance between the two is large, making it difficult to join by soldering. There is a risk of contact with the metal case or the second lead wire due to the slack required for the work, resulting in a short circuit. In order to prevent this short circuit, a thin insulating coating made of enamel or the like is formed on the surface of the lead wire, but it lacks mechanical strength and is not necessarily perfect.

As a countermeasure to this, it is possible to increase the insulation by inserting the first lead wire into a thin insulating tube made of soft synthetic resin, rubber, etc. However, as mentioned above, the first lead wire
The long lead wires of the lead wires increased the weight of the lead wires, and the piezoelectric element that was joined by brazing was subjected to a large tensile load, which adversely affected the frequency characteristics and sensitivity, making it difficult to put it to practical use.

The present invention has successfully solved the above-mentioned drawbacks of ultrasonic microphones, and the embodiments shown in the drawings will be described below.

1 and 2, in both figures, 1 is a thin metal case formed into a bottomed cylindrical shape by press working, etc., and 2 is a metalized electrode surface (hereinafter referred to as , simply referred to as electrode surface) 2a,
2b is a piezoelectric element made of a polarized lead zirconate titanate compound, etc., with one (first) main surface, in this case the 2a side, exposed downward, and the other (second) electrode surface The 2b side is concentrically attached to the inner bottom surface 11 of the metal case 1 with an adhesive or the like (not shown). 3 is an insulating substrate on which a pair (first and second) terminal legs 3a and 3b are implanted, and is fitted and sealed with the open end of the metal case 1; 4a is exposed facing the insulating substrate 3; A first lead wire 4b connecting the first electrode surface 2a of the piezoelectric element 2 and the first terminal leg 3a of the insulating substrate 3 is a first lead wire 4b of the piezoelectric element 2.
A second lead wire is shown that connects the inner peripheral surface of the side wall of the metal case 1 and the second terminal leg 3 of the insulating substrate 3, which are electrically connected by joining the second electrode surface 2b of the This is a general structure of a sonic microphone, but in the present invention, a first lead wire surrounds the first terminal leg 3a implanted in the insulating substrate 3 and connects the terminal leg 3a and the piezoelectric element 2. 4a, the insulating tube is made of silicone rubber, fluorine rubber, known as a vibration absorbing material, or various types of sponge, as shown by reference numeral 5 in FIG. The first lead wire 4a is made of a soft material such as a polymeric material having a shape, and a part of the first lead wire 4a is lightly abutted against both opposing main surfaces of the piezoelectric element 1 and the insulating substrate 3, and the entire first lead wire 4a is held in a seated state. enclosing or providing an axial distance g between the piezoelectric element 1 and the piezoelectric element 1 as shown by reference numeral 5' in FIG.
The overall height may be reduced so as to surround most of the lead wire 4a except for the area where it joins with the first electrode surface of the piezoelectric element. In this case, a hard synthetic resin may be used. Further, it can be molded integrally with the insulating substrate 3.

As described above, the ultrasonic microphone of the present invention has a long wire connecting the electrode surface of the piezoelectric element on the side facing the insulating substrate attached to the inner bottom surface of the metal case and the terminal leg implanted in the insulating substrate. Since the slack lead wire is surrounded by an insulating tube provided around the terminal leg, it has an excellent effect of ensuring insulation from the metal case and other metal parts under any conditions. .

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of the ultrasonic microphone of the present invention, and FIG. 2 is a longitudinal sectional view showing another embodiment. DESCRIPTION OF SYMBOLS 1... Metal case, 1a... Inner bottom surface, 2... Piezoelectric element, 2a... One electrode surface, 2b... Other electrode surface, 3... Insulating substrate, 3a, 3b... A pair of terminal legs, 4a, 4b...a pair of lead wires, 5,
5'...Insulating tube.

Claims (1)

[Scope of utility model registration request] A bottomed cylindrical metal case, in which a piezoelectric element with metalized electrode surfaces formed on both main surfaces is adhered to the inner bottom surface, is sealed onto an insulating substrate on which a pair of terminal legs are implanted, and the insulating substrate and One electrode surface of the piezoelectric element, which is exposed facing each other, is directly bonded to the inner bottom surface of the metal case, and the other electrode surface of the piezoelectric element is connected to the insulating substrate through a pair of lead wires, respectively, through the metal case. An insulating tube that maintains the insulation of the lead wire on the electrode surface side of the piezoelectric element exposed facing the insulating substrate is placed around the terminal leg of the insulating substrate connected to the lead wire. An ultrasonic microphone characterized by the following: