JPH0622232Y2 - Ultrasonic switch - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] This invention uses an ultrasonic transducer to generate an ultrasonic signal, and the time until the emitted ultrasonic wave hits the object to be inspected and returns. The present invention relates to an ultrasonic switch that measures a distance from a to-be-inspected object and determines whether or not the inspected object is within a preset distance, and particularly to a support structure for the ultrasonic transducer.

[Conventional technology]

In order to use the ultrasonic vibrator for the ultrasonic switch, it is necessary to attach the ultrasonic vibrator to the sensor case. A conventional mounting support structure will be described with reference to FIGS. 3 and 4.

In the ultrasonic transducer 1, for example, a disc-shaped resonator 1b smaller than the outer diameter of the matching layer 1a is bonded to the central portion of the back surface of an insulating disc-shaped matching layer 1a such as epoxy, and A cylindrical metal tube (for example, aluminum) 1c having the same diameter as the outer diameter of the matching layer 1a is covered on the resonator 1b, and the upper end surface of the metal tube 1c is bonded to the back surface of the matching layer 1a. Lead wires 1d and 1e are drawn out from the lower surface (positive electrode) and the upper surface (negative electrode) of the resonator 1b. The ultrasonic transducer 1 configured as described above is housed in the sensor case 3 via the sensor cushion 2, and the outer peripheral side surface of the matching layer 1a of the ultrasonic transducer 1 and the metal tube.
An insulating adhesive 4 such as silicon rubber is provided in a space between a part of the outer peripheral side surface of 1c and the inner peripheral side surface of the sensor case 3.
Is injected and glued.

[Problems to be solved by the device]

In the ultrasonic switch configured as described above, the matching layer 1a of the ultrasonic transducer 1 is surrounded by the outer peripheral side surface of the adhesive 4 and adhered thereto, so that the matching layer 1a is restrained by the adhesive 4 and is free. Vibration is not possible. Therefore, there is a problem that the sensitivity of the ultrasonic transducer 1 stored in the sensor case 3 is significantly reduced as compared with the ultrasonic transducer 1 in a single state not stored in the sensor case 3. Therefore, unless a single ultrasonic transducer with extremely high sensitivity (more than necessary) is prepared, the expected sensitivity function cannot be obtained when the ultrasonic transducer is housed in the sensor case 3, and the yield is very poor. It was

In view of the above-mentioned circumstances, it is an object of the present invention to improve the support structure of the ultrasonic vibrator so that the sensitivity does not decrease even if the ultrasonic vibrator is housed in the sensor case.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention provides a disc-shaped matching layer, a resonator having a disc shape smaller than the outer diameter of the matching layer, and a resonator bonded to the center of the back surface side of the matching layer; A metal cylinder that surrounds the resonator in a cylindrical shape having the same outer diameter and is provided on the back side of the matching layer, and is a super-electrode that electrically connects the negative electrode of the resonator and the metal cylinder. A surface of the matching layer, which is opposite to the surface of the matching layer to which the resonator is bonded, is exposed to a sensor case having a bottomed cylindrical shape having an outer diameter larger than that of the ultrasonic vibrator. The sensor cushion is arranged between the metal cylindrical tube of the ultrasonic transducer and the bottom of the sensor case, and an adhesive is filled between the outer periphery of the ultrasonic transducer and the sensor case. In the ultrasonic switch, the adhesive is a metal cylindrical tube and a sensor case. A foamable silicon sponge is filled between the outer surface of the matching layer and the sensor case, which is the upper surface of the adhesive, and the exposed surface of the foamable silicon sponge is treated with a silicon film. It is characterized by being.

[Operation] In the ultrasonic switch according to the present invention, the adhesive for bonding the sensor case and the ultrasonic transducer is filled between the metal cylindrical tube and the sensor case, and the upper surface of the adhesive is the matching layer. By arranging the foamable silicone sponge between the outer peripheral surface and the sensor case, the matching layer can freely vibrate without being constrained by the adhesive. Further, since the surface of the foamable silicon sponge is treated with a silicon film, outside air moisture does not permeate into the foamable silicon sponge and maintains electrical insulation from the outside. Since this silicon film is thin, flexible and tough, it does not restrain the matching layer.

〔Example〕

FIG. 1 is a plan view of an ultrasonic switch according to an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of the ultrasonic switch.
The lower part of the metal tube 1c of the ultrasonic transducer 1 is the sensor cushion 2
The metal tube 1c is attached to the sensor case 3 via an adhesive, and the upper portion of the metal tube 1c is adhered to the sensor case 3 with an adhesive 4. The space between the outer periphery of the matching layer 1a of the ultrasonic transducer 1 and the inner periphery of the sensor case 3 is filled with a foamable silicon sponge 5, and the upper surface of the foamable silicon sponge 5 is aligned with the outer periphery of the matching layer 1a and the sensor case. The inner periphery is covered with a silicon film 6 so as to cover it. In such a structure, the matching layer 1a is not adhered to the sensor case 3 by an adhesive as in the conventional case and is held by the flexible and elastic foaming silicon sponge 5, so that the matching layer 1a is less constrained and the matching layer 1a is free. Can vibrate. Since the upper surface of the foamable silicon sponge 5, which easily absorbs moisture from the outside, is covered with the silicon film 6, electrical insulation is maintained without absorbing moisture from the outside. Further, since the silicon film 6 is flexible and tough, it does not restrain the matching layer 1a.

[Effect of device]

As described above, according to the present invention, the adhesive for bonding the sensor case and the ultrasonic transducer is filled between the metal cylindrical tube and the sensor case, and is the upper surface of the adhesive, which is the matching layer of the matching layer. Since the foaming silicone sponge is arranged between the outer peripheral surface and the sensor case, the matching layer and the sensor case are not adhered by the adhesive, so that the matching layer is not restricted by the adhesive and can freely vibrate. Therefore, the reduction in the sensitivity of the ultrasonic transducer is reduced. The following table shows the results of experiments conducted to reduce this sensitivity.

The sensitivity reduction rate referred to here is a value obtained by the following.

Due to the reduction in the sensitivity of the ultrasonic transducer described above, the reduction rate of the wave transmission / reception sensitivity after mounting was large and could not be used until the wave transmission / reception sensitivity after mounting had been confirmed. This has the advantage that the yield is good without the need to check the wave transmission / reception sensitivity later.

On the other hand, since the foamable silicon sponge is apt to be absorbed with water, if the moisture from the outside enters the foamable silicon sponge, the electrical insulation from the outside is deteriorated. The surface that is in contact with the outside air when the child is installed in the sensor case is covered with a strong and thin silicon film that is water repellent and flexible, and moisture from the outside air does not enter the foaming silicon sponge. It is possible to prevent deterioration of electrical insulation. Further, since the foamable silicon sponge does not lose its elasticity due to the coating of the silicon thin film, the matching layer is not restricted.

[Brief description of drawings]

FIG. 1 is a plan view of an ultrasonic switch according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view thereof, FIG. 3 is a plan view of a conventional ultrasonic switch, and FIG. 4 is a longitudinal sectional view thereof. is there. 1: ultrasonic transducer, 1a: matching layer, 1b: resonator, 1c: metal tube, 2: sensor cushion, 3: sensor case, 4: adhesive, 5: silicon sponge, 6: silicon film.

Claims (1)

[Scope of utility model registration request] 1. A disc-shaped matching layer, a resonator having a disc shape smaller than the outer diameter of the matching layer and bonded to the center of the back surface side of the matching layer, and a diameter the same as the outer diameter of the matching layer. A cylindrical cylinder surrounding the resonator and provided on the back surface side of the matching layer, and an ultrasonic transducer electrically connecting the negative electrode of the resonator and the cylindrical metal tube. The ultrasonic transducer is housed in a sensor case having a bottomed cylindrical shape having an outer diameter larger than that of the ultrasonic transducer such that the surface opposite to the surface to which the resonator of the matching layer is bonded is exposed. An ultrasonic switch in which a sensor cushion is arranged between the metal cylindrical tube of the ultrasonic oscillator and the bottom of the sensor case, and an adhesive is filled between the outer periphery of the ultrasonic oscillator and the sensor case. The adhesive is filled between the metal cylindrical tube and the sensor case, and A foamable silicon sponge is disposed between the sensor case and the outer peripheral surface of the matching layer, and the exposed surface of the foamable silicon sponge is treated with a silicon film. Ultrasonic switch.