JPH0535640B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an ultrasonic transducer used in an ultrasonic distance measuring device or the like.

Configuration of conventional examples and their problems The frequencies used in conventional ultrasonic distance measuring devices range from 20 KHz to 100 KHz at most, and in this frequency range, the wavelength is relatively long and the external noise level is high, so high accuracy is not possible. It was not possible to measure the distance. In order to increase distance resolution and reduce distance measurement errors caused by external noise, it is necessary to use ultrasonic waves in a high frequency range with short wavelengths and low external noise levels. Since the absorption coefficient of ultrasonic waves increases and the attenuation of ultrasonic waves in the propagation path increases, it is unsuitable for measuring long distances, and has the disadvantage that it can only be applied for close distance measurements. When measuring distance using a single frequency like this, 100KHz
When ultrasonic waves with the following relatively low frequencies are used, the distance measurement accuracy becomes insufficient especially at close distances where high accuracy is required.When ultrasonic waves with high frequencies of several hundred kilohertz or more are used, the distance measurement accuracy at close distances becomes insufficient. It improved, but it was not possible to measure long distances.

In order to compensate for these shortcomings, it has been considered to install a low-frequency ultrasonic transducer for long-distance measurement and a high-frequency ultrasonic transducer for close-range, high-precision measurement, and to switch between them. Because two or more ultrasonic transducers are placed side by side, the size increases, and the central axes of the sound wave radiation of each ultrasonic transducer do not match, so the measurement location on the object to be measured differs depending on the ultrasonic transducer. This will cause measurement errors.

Purpose of the Invention The present invention has been made to solve the above-mentioned problems of the conventional art, and is intended to reduce measurement errors when performing ultrasonic measurements such as distance measurement using ultrasonic waves of two different frequencies. The object of the present invention is to provide a small and lightweight ultrasonic transducer that has a small amount of noise and a wide measurement distance range.

Structure of the Invention The present invention achieves the above object, and includes: a first ultrasonic vibrator section that performs thickness vibration; a second ultrasonic vibrator section that performs radial expansion vibration; A cylindrical body having an inner circumferential surface and an outer circumferential surface, including a conical reflector for converting the radiation direction of the ultrasonic waves emitted by the child part, one end being open and the other end being closed. , the second ultrasonic transducer section is placed on the inner circumferential surface, the conical reflector is placed in the internal space surrounded by the inner circumferential surface, and the first ultrasonic transducer is placed on the conical reflector. A sonic transducer section is provided, and each of the first ultrasonic transducer section, the second ultrasonic transducer section, and the truncated cone-shaped reflector are held in a single casing so that their central axes coincide with each other. There is provided an ultrasonic transducer characterized by:

DESCRIPTION OF EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of the ultrasonic transducer of the present invention, and a is a cross-sectional view;
b shows a plan view. Reference numeral 1 denotes a thick vibrating disk-shaped vibrator made of piezoelectric ceramic or the like, 2 a radially expanding vibrating cylindrical vibrator made of voltage ceramic or the like, and one side of the disk-shaped vibrator 1 is provided with a backing material 3 in the shape of a truncated cone. The disc-shaped vibrator 1 and the bucking material 3 are arranged inside the cylinder of the cylindrical vibrator 2 such that their central axis 6 coincides with the central axis 6 of the cylindrical vibrator 2. 4 is a cylindrical vibrator 2
A hollow cylindrical backing material is formed in close contact with the outer circumferential side surface of the backing material, and 5 is a housing that holds the above-mentioned vibrator and backing material. If the top expansion angle θ of the conical truncated bucking material 3 is selected to be 45 degrees, the ultrasonic waves emitted by the radial expansion vibration of the cylindrical vibrator 2 will be transmitted by the bucking material 3 as shown by arrow 7. It is reflected and the sound wave radiation direction is changed forward.

According to this embodiment, ultrasonic waves of several 100 KHz or higher can be easily transmitted by the thickness vibration of the disc-shaped vibrator 1, so distance measurement at close ranges can be performed with high precision. Since ultrasonic waves of several low frequencies can be transmitted by the radial expansion vibration of the cylindrical vibrator 2, it becomes possible to extend the distance measurement range to a long distance.

In addition, since the central axes of transducers 1 and 2 are arranged to coincide, the central axes of the ultrasonic beams emitted from each transducer coincide, and therefore the positions of the measurement centers on the object to be measured coincide. Therefore, accurate measurements are possible. Furthermore, since the bucking material 3 of the disc-shaped vibrator 1 is used as a reflector for converting the ultrasonic radiation direction of the cylindrical vibrator 2, there is no need to separately provide a reflector such as a conical horn, and the disc-shaped vibration Since the element 1 and bucking material 3 are arranged in the cylindrical inner space of the cylindrical vibrator 2, it is possible to downsize the vibrator.

In addition, in the figure, the opposite slope of the bucking material 3 on the truncated cone that also serves as a reflector is not necessarily flat, and the ultrasonic waves from the vibrator exhibiting radial expansion vibration are reflected by the ultrasonic waves from the vibrator exhibiting thickness vibration. It may be any surface that reflects parallel to the direction of , and may be a paralloid surface, an exponential surface, etc., for example.

Effects of the Invention In summary, the present invention provides a first ultrasonic transducer section that performs thickness vibration, which is responsible for short-distance measurement, and a truncated conical reflector provided on its back surface, and a diameter It is placed inside the second ultrasonic transducer section that performs directional spread vibration, and the radiation surface of the ultrasonic wave from the second ultrasonic transducer section after being reflected on the opposite slope of the truncated conical reflector is at the center. This system forms a ring-shaped sound field distribution with a region where the ultrasonic power is zero.As a result, the directional characteristics of ultrasonic waves are sharp over long distances, and the reflected ultrasonic beams reach It is possible to realize a small and lightweight ultrasonic transducer that can increase the distance, has a wide measurable distance range, has little measurement error.

[Brief explanation of the drawing]

FIG. 1 shows the structure of an ultrasonic transducer according to an embodiment of the present invention, in which a is a sectional view and b is a plan view. DESCRIPTION OF SYMBOLS 1... Thickness vibration ultrasonic transducer, 2... Radial expansion vibration ultrasonic transducer, 3, 4... Backing material, 5... Housing, 6... Ultrasonic transducer central axis, 7
...Ultrasonic beam.

Claims (1)

[Claims] 1. A first ultrasonic transducer section that performs thickness vibration;
a second ultrasonic transducer section that performs radial expansion vibration; and a truncated cone-shaped reflector for converting the radiation direction of the ultrasonic waves emitted by the second ultrasonic transducer section. equipped, one end is open, the other end is closed,
A cylindrical body having an inner circumferential surface and an outer circumferential surface, the second ultrasonic transducer part is placed on the inner circumferential surface, the conical truncated reflector is placed in an internal space surrounded by the inner circumferential surface, and the conical truncated reflector is arranged in a conical shape. A first ultrasonic transducer section is provided on each of the trapezoidal reflectors, and the central axes of the first ultrasonic transducer section, the second ultrasonic transducer section, and the conical truncated reflector are respectively provided. An ultrasonic transducer characterized in that the ultrasonic transducer is held in a single casing so as to match. 2. The truncated cone-shaped reflector is shaped like a truncated cone with a spread angle of about 45°, a disk-shaped vibrator is provided as the first ultrasonic transducer section on the surface of the truncated cone, and the reflector is 2. The ultrasonic transducer according to claim 1, wherein the ultrasonic transducer acts as a bucking material for the first ultrasonic transducer section, and the second ultrasonic transducer section is a cylindrical transducer.