JPH0236700A - Ultrasonic ceramic microphone - Google Patents

Abstract

PURPOSE:To reduce echo in a cylindrical case caused when a piezoelectric ceramic plate is driven by a tone burst wave by pressing the entire part of the piezoelectric ceramic plate into contact with the entire inner face of a conical truncated part of the cylindrical case by means of a vibration proof member and packing the inside of the cylindrical case by an elastic member. CONSTITUTION:A felt group vibration proof member 12 having lots of air layers is pressed into contact with the entire face of the piezoelectric ceramic plate 10 and the entire inner face of the conical truncated part of the cylindrical case 11 by using a resonance ring 13 as a stopper, the resonance ring 13 is inserted in the cylindrical case 11 and fixed at the upper face of the conical truncated part. A terminal board 15 is in contact with the resonance ring 13 via the spacer 14 made of an elastic member and inserted and fixed in the cylindrical case 11. The elastic member 19 is packed in a way that the terminal board 15 and the cylindrical case 11 are sealed. Thus, when the applied voltage to the piezoelectric ceramic plate is finished, the generated residual vibration is suppressed, the echo component is reduced and the detection and range finding of an object located at a near distance are attained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an ultrasonic ceramic microphone that transmits and receives ultrasonic waves and is used as a short-range object detector, proximity switch, or distance meter.

2. Description of the Related Art A conventional ultrasonic ceramic microphone of this type will be explained with reference to FIG. In FIG. 3, reference numeral 1 denotes a piezoelectric ceramic plate, and the piezoelectric ceramic plate 1 is pasted to the bottom surface 2a of a cylindrical case 2 having a truncated conical cross section to form a unimorph vibrator.

Reference numeral 3 denotes a resonance ring, which is fixed to the upper inner surface of the cylindrical case 2. A terminal plate 4 is inserted into the cylindrical case 2 and fixed in contact with the resonance ring 3 via a spacer 6 made of an elastic member. 6 is an elastic adhesive, and the terminal board 5
and the cylindrical case 2 are injected so that the space between them is sealed.

7a is a lead wire, one of which is soldered to a terminal 8a implanted in the terminal board 4, and the other end is soldered to the electrode surface of the full-piezoelectric ceramic board 1. 7b is a lead wire, one of which is soldered to the terminal 8b, and the other is bonded to the contact surface of the cylindrical case 2 and the resonance ring 3 through a conductive adhesive 9.

Problems to be Solved by the Invention In such a conventional configuration, when a tone burst wave as shown in FIG. At the same time that the ultrasonic waves are emitted into the air, vibrations are also transmitted to the inside of the cylindrical case 2, such as the side surface of the cylindrical case 2, the resonance ring 3, and the lead wires 7a and 7b, and the applied voltage is terminated. However, there are cases in which vibrations remain inside the cylindrical case 2, and the vibrations conversely vibrate the piezoelectric ceramic plate 1 to output an electric signal. Then, this electric signal becomes a reverberant signal as shown in FIG. 2, and there is a problem that this reverberant signal cannot be received for a certain time (T1).

The present invention is intended to solve these problems, and aims to shorten the reverberation within the cylindrical case that occurs when a piezoelectric ceramic plate is driven by a tone burst wave.

Means to Solve All the Problems In order to solve this problem, the present invention has provided that the entire piezoelectric ceramic plate and the entire inner surface of the truncated conical portion of the cylindrical case are pressed together with a vibration isolating material, and the inside of the cylindrical case is covered with an elastic member. It is filled with.

Effect: According to this configuration, a tone burst wave is applied to the full-pressure electromagnetic plate, and when the applied voltage is finished, the imaging of the piezoelectric ceramic plate and the vibration of the side surface of the truncated conical portion of the cylindrical case are caused by the piezoelectric ceramic plate and the cylindrical case. Vibration is suppressed by the vibration isolating material that is pressed against the entire inner surface of the case.
Residual vibration becomes smaller. In addition, since the inside of the cylindrical case is filled with an elastic material, it is possible to eliminate air resonance that occurs inside the case, and also to completely suppress the vibration of the lead wires, which reduces the voltage applied to the piezoelectric ceramic plate. This means that the reverberation component due to residual vibration that occurs when the process is finished can be significantly reduced.

Embodiment FIG. 1 is a sectional view of an ultrasonic ceramic microphone according to an embodiment of the present invention. In FIG. 1, 10 is a piezoelectric ceramic plate, and a cylindrical case 11 having a truncated conical cross section.
This piezoelectric ceramic plate 10 is entirely bonded to the bottom surface 11a of the unimorph resonator. Reference numeral 12 denotes a felt-based vibration damping material having a large number of air spaces, which is pressed against the entire piezoelectric ceramic plate 10 and the entire inner surface of the truncated conical portion of the cylindrical case 11 using a resonance ring 13 as a stopper. The resonance ring 13 is inserted into the cylindrical case 11 and fixed on the upper surface of the truncated conical portion. A terminal plate 15 is inserted into the cylindrical case 11 and fixed in contact with the resonance ring 13 via a spacer 14 made of an elastic member. Reference numeral 19 denotes an elastic member, which is injected so as to seal between the terminal plate 16 and the cylindrical case 11. 1γ& is a lead wire, and connect one side of this lead wire 1rya to the terminal 16& implanted in the terminal board 16.
・The other end is soldered to the electrode surface of the piezoelectric ceramic plate 10. 17b is the other lead wire. One of the lead wires 1 is soldered to the terminal 16b, and the other is glued to the contact surface of the fully cylindrical case 11 and the resonance ring 13 via a conductive adhesive 18. There is. The entire inside of the cylindrical case 11 is filled with the elastic member 19.

As described above, according to this embodiment, a tone burst wave as shown in FIG.
The vibration of the truncated conical portion 1 is suppressed by the vibration isolating material 19 that is in pressure contact with the piezoelectric ceramic plate 10 and the inner surface of the truncated conical portion of the cylindrical case 11, thereby reducing residual vibration. Also, the cylindrical case 11
Since the inside of the lead wire 17a is filled with an elastic member 19, vibration of the side surface of the cylindrical case 11 is completely prevented.

It is possible to completely suppress even the slightest vibration, and air resonance inside the cylindrical case 11 does not occur.

Therefore, when the voltage applied to the piezoelectric ceramic plate 1o ends, the residual vibration that occurs can be extremely suppressed, so that the reverberation component can be significantly shortened as shown in FIG. 2C, and the reverberation The time (T2) during which the signal is present is short.

Effects of the Invention As described above, according to the present invention, a vibration isolating material that is pressed against the entire piezoelectric ceramic plate and the entire inner surface of the truncated conical portion of the cylindrical case;
By providing an elastic member that fills the inside of the cylindrical case, it is possible to suppress all residual vibrations that occur when the voltage applied to the piezoelectric ceramic plate ends, so that the reverberation component is reduced as shown in Figure 2C. It becomes possible to significantly shorten the
This has the effect of realizing short-range object detection and distance measurement.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an ultrasonic ceramic microphone according to an embodiment of the present invention, FIG. 2 a is a diagram showing a tone burst wave signal applied to the ultrasonic ceramic microphone, and FIG. FIG. 2C is a diagram showing all the reverberation waves when the entire tone burst wave signal is applied to the ceramic microphone. FIG. 2C is a diagram showing the reverberation waves when the tone burst wave signal is applied to the ultrasonic ceramic microphone of the present invention.
The figure is a sectional view showing a conventional ultrasonic ceramic microphone. 1o... Piezoelectric ceramic plate, 11... Cylindrical case, 111L... Bottom surface, 12... Vibration isolating material, 13... Common Shooting ring, 14...
Spacer, 15...Terminal board, le&, 151)
...Terminal, 1a2L, 1endb...Lead wire, 18...Conductive adhesive, 19...
・Elastic member. Name of agent: Patent attorney Shigetaka Awano and 1 other person 2 figures lo---2E Denmagure version 11- Komakin Goose/l Hisu-, bottom 12-11 Bo Nuki, 13-11 Hong Jyoen War〉ri゛14-nuhe0-sa15---[Bi-print Condolence Figure 3/2

Claims (1)

[Claims] A unimorph vibrator is constructed by bonding a piezoelectric ceramic plate to the bottom inner surface of a cylindrical case having a truncated conical cross section, and a vibration isolating material is pressed against the entire piezoelectric ceramic plate and the truncated conical inner surface of the cylindrical case. and an elastic member filling the inside of the cylindrical case.