JPS5830385Y2 - ultrasonic ceramic microphone - Google Patents

Description

[Detailed Description of the Invention] The present invention provides an ultrasonic ceramic microphone that utilizes pulses in an ultrasonic remote control device and can be used in a remote control circuit.

Conventional ultrasonic ceramic microphones were used by continuously oscillating monotonous frequencies, so the design direction was to simply improve vibration efficiency in order to improve sensitivity at a certain frequency. It seems that they have taken this into consideration.

Therefore, the ultrasonic ceramic microphone of the conventional structure described below has poor pulse fall characteristics, resulting in a decrease in fidelity in a remote control device using pulses.

An example of a conventional microphone will be explained using FIG. 1.

A conical resonator (made of metal) 3 is added to the center of a bimorph resonator in which a piezoelectric ceramic resonator 1 and a metal diaphragm 2 are bonded together to form a composite resonator.

The composite resonator is attached to the terminal plate 5 via an elastic adhesive 6, and the composite resonator and the terminal plate 5 are enclosed in a case 4 to constitute an ultrasonic ceramic microphone.

In this structure, since the conical resonator 3 is made of metal (aluminum) and is thin with a thickness of 0.3 mm or less, variations in size and shape of the conical resonator 3 occur during vibration transmission. It was found that various resonance phenomena occurred, and resonance phenomena that were not a problem with continuous vibration appeared on the pulse characteristics.

As mentioned above, the long fall times that occur when pulses are used are caused by the structure of the ultrasonic ceramic microphone, and experimental results have revealed that the metal conical resonator has a particularly large effect. .

The present invention is an attempt to improve this type of ultrasonic ceramic microphone, and to provide one that can be sufficiently applied to devices using pulses with small pulse gaps.

Embodiments of the present invention will be described below with reference to the drawings.

A bimorph vibrator is constructed by bonding a piezoelectric ceramic vibrator 8 and a metal or resin diaphragm, or two piezoelectric vibrators 9, and performs electrical signal-flexural vibration conversion.

A metal conical resonator 10 is attached via a coupling shaft 11 to the center portion of the bimorph resonator where the vibration amplitude is large.

The coupling shaft 11 strengthens the coupling degree of the vibrator and adjusts the frequency, and in the present invention, the desired characteristics can be obtained without using the coupling shaft.

A conical resonator formed by coating the entire conical resonator thinly with a resin or elastic adhesive 12, or by providing an adhesive on the inside of the conical resonator 10 at a height h greater than +h of the conical resonator height h. By using a resonator, we were able to obtain a microphone that can have a very short vibration damping time when using pulse waves or when removing signals.

It is understood that this occurs because the resonance at the unique resonance frequency of the metal conical resonator 10 continues for several m5ec even after the signal is erased. As a result of considering using different materials around the resonator to mutually absorb vibrations, we found that by coating the resonator with a thin layer of resin adhesive, we were able to reduce the pulse fall time to 1-1.5 m5ec. 5 m5
I was able to make it below ec.

In addition, the conical resonator 10 has the function of amplifying the vibrations of the bimorph resonator as in the past, and even if coated with the resin or elastic adhesive 12, by creating an appropriately thin film, the sensitivity will not decrease. is not a problem.

13 is a terminal plate, and the bimorph vibrator is attached with an elastic adhesive 1.
7, and the composite resonator formed by attaching the conical resonator 10 to the bimorph resonator and the terminal plate 13 are enclosed in the case 14.

Terminals 15a and 15b are connected to the upper and lower electrode surfaces of the bimorph vibrator via lead wires 16a and 16b, and are used for external input and output.

As described above, according to the present invention, it is possible to provide an ultrasonic ceramic microphone with excellent pulse fall characteristics.

As shown in Figure 4, the characteristics are approximately 1
m5ec short pulse characteristic a is obtained.

Furthermore, in the sensitivity-frequency characteristics, there is almost no ripple, and stable characteristics can be obtained.

Recent remote control devices for television receivers are required to have multiple functions, but in order to meet the above requirements using a resonant ultrasonic ceramic microphone, a digital remote control using pulses is required. Equipment is becoming the main focus.

It is expected that by using the microphone of the present invention, it will be possible to exhibit stable characteristics for use in digital systems and to be able to have more functions.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a conventional ultrasonic ceramic microphone, Fig. 2 is a cross-sectional front view of an ultrasonic ceramic microphone according to an embodiment of the present invention, Fig. 3 is an exploded perspective view of the main parts, and Fig. 4 is a cross-sectional view of a conventional ultrasonic ceramic microphone. It is a characteristic diagram for explaining the same microphone. 8... Piezoelectric ceramic vibrator, 9... Piezoelectric ceramic vibrator or metal resin diaphragm, 10...
Metal conical resonator, 12... Resin or elastic adhesive, ]3... Terminal board, 14... Case.

Claims (1)

[Scope of utility model registration request] A composite resonator is constructed by adding a metal conical resonator to the center of a bimorph resonator made by laminating a piezoelectric ceramic resonator and a metal or resin diaphragm, or two piezoelectric ceramic resonators. An ultrasonic ceramic microphone in which this composite resonator is elastically fixed to a terminal plate and enclosed in a case, and the metal conical resonator is thinly coated with resin or elastic adhesive.