JPS5811156B2 - ultrasonic horn - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a throat section 2 of the horn 1, which has a flat or circular diameter that gradually increases from the throat section 2 toward the opening.
The distal end portions of the cylindrical body 3 are integrally connected, the inner periphery of the distal end of the cylindrical body 3 is formed as a reduced diameter portion 4, and the inner circumference of the proximal end of the cylindrical body 3 is formed as an enlarged caliber portion 5, A cylindrical body 8 having an inner circumferential body that gradually becomes larger from the distal end toward the proximal end and having an ultrasonic transducer 12 attached to the proximal end portion is inserted into the enlarged diameter portion 5 of the cylindrical body 3. The purpose of the present invention is to provide an ultrasonic horn whose directivity pattern is stable against changes in ambient temperature.

FIG. 1 shows a conventional example of the present invention, in which a cylindrical body 3 is attached to the throat part 2 of a horn 1 which is flat or circular and has a gradually enlarged diameter.
The cylindrical body 3 is provided with a reduced aperture portion 4 and an enlarged aperture portion 5, which are integrally connected to each other. Ultrasonic waves having a predetermined directivity pattern are generated from the

By the way, to express the directivity sharpness of an ultrasonic horn,
Generally, as shown in FIG. 2, an angle at a level 6 (dB) lower than the maximum value of the directivity level L is used as the half-value angle α.

Therefore, an example of temperature-directional characteristic measurement data of the conventional ultrasonic horn shown in FIG. 1 is shown in FIG. The mouth is characteristically shown in the elliptical direction.

Based on the above data, the half-value angle-temperature characteristic diagram of the ultrasonic horn shown in Fig. 1 is shown in Fig. 4, and α1 in the same figure is
is the characteristic in the oval direction of the ultrasonic horn, and α2 is the characteristic in the short circle direction.

When the half-power angle α changes in this manner, the detection area of the ultrasonic horn or the ultrasonic switch used also changes as the temperature changes, as shown in FIG. 5.

In other words, when the temperature changes from -20°C to +40°C, the detection area changes by as much as 45% in the oval direction.

The cause of this change is that the directivity pattern of the ultrasonic horn changes as the wavelength changes.

In other words, when the temperature changes, the speed of sound V becomes V=331.0 +
This is because when the speed of sound V changes, the wavelength λ changes according to the equation shown as λ--(mt, where f is the frequency). .

Here, the frequency of the ultrasonic transducer 12 is 39.5 KHz.
The following table shows the change in wavelength λ with respect to temperature change when

As is clear from the table above, the ambient temperature is between 120°C and +
It can be seen that the wavelength changes by a little less than 15% when the temperature changes up to 60°C.

The present invention has been made to solve the above-mentioned drawbacks, and one embodiment thereof is shown in FIG.

In the figure, 1 is a flat horn with a gradually enlarged diameter, 2 is the throat of the horn 1, and 3 is a cylindrical body connected to the throat 2 of the horn 1 at its tip, and the inner peripheral body of the tip is It has a reduced diameter portion 4, and the inner circumferential body at the base end has an enlarged diameter portion 5.

Further, a partition plate 7 having an elongated hole 6 is provided in the middle of the reduced diameter portion 4 of the cylindrical body 3 so that the long axis direction of the elongated hole 6 is perpendicular to the long axis direction of the diameter of the horn 1. It has become.

Further, a cylindrical body 8 is inserted into the base end of the enlarged caliber part 5 of the cylindrical body 3, and the cylindrical body 8 includes a small caliber part 9 whose inner circumference is smaller than that of the reduced caliber part 4; A large diameter part 10, 10' of the inner circumferential body provided at the base end of the aperture part 90, and a reduced diameter part which is provided at a part of the tip of the small diameter part 9 and is smaller than the inner circumferential body of the enlarged aperture part 5. The outer peripheral side 11 is provided.

Reference numeral 12 denotes an ultrasonic vibrator, which is constructed by attaching a pair of electrodes to both sides of a piezoelectric crystal piece. When a high-frequency voltage is applied between the pair of electrodes, the piezoelectric crystal piece vibrates and generates ultrasonic waves. The horn 1 emits ultrasonic waves having a predetermined directivity.

The actual dimensions of each part are as follows.

Temperature 1.6λφ, g is 2λφ, h is 1.2λφ, i is 1
．． 6λφ, j is 1.7λφ.

Therefore, when the ambient temperature changes between -20°C and +40°C, the change in wavelength λ is 8.07 mm to 8.0 mm when the frequency is 39.5 KHz, as shown in the table above.
．． It varies up to 99mm.

FIG. 7A 50 shows an example of measurement data of the temperature-directivity characteristics of the ultrasonic horn in the above embodiment, where A shows the characteristics in the oval direction of the horn 1, and the mouth shows the characteristics in the short circle direction, respectively.
α indicates the half-value angle.

FIG. 8 shows the relationship between the half-value angle α of the directivity pattern of the ultrasonic horn in the above embodiment and the wavelength λ, where α1 is the change in the half-value angle α in the elliptical direction of the horn 1, and α2 is the change in the half-value angle α in the elliptical direction. According to the ultrasonic horn of this example, the half-value angle α changes by 11% in the elliptical direction and 10% in the elliptical direction when the wavelength λ is between 8.07 mm and 8.99 mm. It can be seen that the change in the half-value angle α is smaller than in the conventional example shown in FIG.

FIG. 9 shows another embodiment, and FIGS. 10A and 10C show other embodiments of the cylindrical body 8 of the present invention. 8.08 mm
Except for the area around 9.29 o'clock, the characteristics are almost the same as the characteristic diagram of half-value angle α and wavelength λ shown in FIG.

Since the present invention is constructed as described above, even if the ambient temperature changes within the normal operating temperature range of 120°C to +40°C, the directivity pattern of the ultrasonic waves emitted from the horn will be The half-value angle of the switch does not change much, and a nearly constant directivity pattern is obtained despite temperature changes.When used in ultrasonic switches, etc., it has the effect of being able to obtain stable operation regardless of temperature changes. It is.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a conventional example of the present invention, Fig. 2 is an explanatory diagram of the half-power angle, Fig. 3 is a temperature-directivity characteristic diagram of the conventional example, and Fig. 4 is the same <half-power angle in the conventional example. Figure 5 is the same temperature characteristic diagram; Figure 6 is a cross-sectional view of an embodiment of the present invention; Figure 7 is the same.
is a temperature-directivity characteristic diagram as above, FIG. 8 is a half-value angle-wavelength characteristic diagram as above, FIG. 9 is a reduced sectional view of another embodiment as above, and FIGS. FIG. 7 is a cross-sectional view showing another example. 1 is a horn, 2 is a throat part, 3 is a cylindrical body, 4 is a reduced diameter part, 5 is an enlarged diameter part, 6 is an elongated hole, 8 is a cylindrical body, and 12 is an ultrasonic transducer.

Claims (1)

[Claims] 1. The tip of the cylindrical body is integrally connected to the throat of the horn, which has a flat or circular diameter that gradually increases from the throat to the opening, and the tip of the cylindrical body has a reduced-diameter part with an inner circumference. At the same time, the inner circumferential shell at the proximal end of the cylindrical body is formed into an enlarged diameter part, and the inner circumferential shell gradually becomes larger from the distal end toward the proximal end, and the ultrasonic transducer is attached to the proximal end. An ultrasonic horn characterized by being inserted into an enlarged diameter portion of a cylindrical body.