JPH0151148B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an ultrasonic transducer for a walking aid for a blind person, which is used for detecting obstacles when a blind person walks.

(Background of the Invention) Recently, the development of a walking aid for the blind using ultrasound has been proposed, and there is a demand for an ultrasound transducer suitable for this use.

Conventionally, this is the first ultrasonic transducer using a small bending type transducer for use in ultrasonic sensors, etc.
I found one with the structure shown in the figure. In this diagram,
A support ring 2 is formed on a substrate 1, and supports a bending type vibrator 3 having a bimorph structure in which two piezoelectric elements are bonded together, and is further aligned with the ultrasonic wave transmitting/receiving surface of the bending type vibrator 3. A device 4 is attached. Electrodes on the upper and lower surfaces of the bending type vibrator 3 are connected to terminal pins 5A and 5B, respectively.

However, in a planar structure using a small bending type vibrator as shown in FIG. 1, the directional beam is broad and it is difficult to reduce side lobes. For this reason, in order to improve the directivity characteristics, a large transducer was used, or a horn was used to narrow down the ultrasonic beam. However, when a large-sized vibrator is used or a combination structure of a small-sized vibrator and a horn is adopted, the overall shape inevitably becomes large.

(Purpose of the Invention) As a result of various experiments, the inventor of the present invention has found that by arranging bent vibrators in a plane so that they are located at each vertex of a triangle and electrically connecting them in parallel to transmit and receive waves, the directivity characteristics can be significantly improved. It was found that this can be improved. Therefore, in the present invention, the directional characteristics can be improved by selecting three of the bending type vibrators arranged at each vertex of a plurality of triangles to be arranged at each vertex of one triangle. The present invention aims to provide an ultrasonic transducer for a walking aid for a blind person that can electrically scan a directional beam by improving the present invention and switching the selection of bending type transducers.

(Embodiments of the Invention) Hereinafter, embodiments of the ultrasonic transducer for a walking aid for a blind person according to the present invention will be described with reference to the drawings while comparing them with a comparative example.

Comparative Example 1 As shown in FIG. 2, the ultrasonic transceiver elements 10 having the structure shown in FIG. 1 were arranged in a straight line, and they were electrically connected in parallel to measure their directional characteristics. The measurement results were as shown in FIGS. 3 to 6. Here, FIG. 3 shows a case where there are two elements 10, FIG. 4 shows a case where there are three elements, FIG. 5 shows a case where there are four elements, and FIG. 6 shows a case where there are five elements. As can be seen from FIGS. 3 to 6, side lobes appear near the directivity direction (0°) and the directivity characteristics are not improved much.

Comparative Example 2 As shown in Fig. 7, four ultrasonic transceiver elements 10 having the structure shown in Fig. 1 were arranged in a square array, connected in parallel, and their directional characteristics were measured.The measurement results were as shown in Fig. 8. As expected, side lobes appear on both sides of the directional direction (0°), and the directional characteristics have not been improved.

Embodiment As shown in FIG. 9, three or more ultrasonic transceiver elements 10 shown in FIG. 1 were arranged on the same substrate 1A so as to form a triangular shape. As shown in FIG. 10, the elements 10 are arranged such that the center of each element is located at the vertex of an equilateral triangle, for example, and the vibration surfaces of the bending type vibrators are on the same plane. And the first
As shown in FIG. 1, three ultrasonic wave transmitting/receiving elements 10 (for example, the elements at positions a, b, and c in FIG. 10 forming a triangle) are selected by the switch means 20 and electrically connected in parallel to the high frequency power source 21. Connect and excite with the same phase. The directional characteristic of the directional beam in this case is the 12th
As shown in the figure, the side lobes on both sides of the directional direction (0°) are significantly suppressed, and the directional characteristics are greatly improved.

(Effects of the Example) As is clear from the above explanation, only when three ultrasonic transceiver elements are selected as in the example and a triangular surface arrangement is formed, a remarkable effect of improving the directional characteristics can be obtained. This makes it possible to realize an ultrasonic transducer that is small (thin), lightweight, and has excellent directional characteristics. It has also become easier to produce a device with performance equivalent to or better than that using a large vibrator or horn. Furthermore, by switching the switch means 20, the triangular array of three selected elements 10 can be moved to different positions over time, thereby electrically scanning the directional beam. Can be done. As a result, it is possible to scan a sharp beam over a wide range, and it can be fully used as an ultrasonic transducer for a walking aid for blind people.

(Supplementary explanation of the embodiment) In Fig. 9, the bending type vibrator 3 is placed on the same substrate.
Although three or more ultrasonic wave receiving elements 10 having the following configuration are arranged in this embodiment, each element may be individually provided in a case and arranged in a triangular arrangement. Further, the configuration of each ultrasonic wave transmitting/receiving element does not necessarily have to be the same as that in FIG. 1, and can be changed as appropriate. For example, a unimorph structure in which a piezoelectric element and a metal plate are bonded together can be used as a bending type vibrator.

(Effects of the Invention) As explained above, according to the ultrasonic transducer for a walking aid for a blind person of the present invention, three of the bending type vibrators arranged at each vertex of a plurality of triangles are By selecting them to be arranged at each vertex position of one triangle, the directional characteristics can be improved, and by switching the selection of bending type vibrators, the directional beam can be electrically scanned. . As a result, obstacles can be reliably detected by scanning with a sharp beam.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an example of a conventional ultrasonic transducer, Fig. 2 is an explanatory diagram showing a linear arrangement configuration in Comparative Example 1, and Figs. 3 to 6 are illustrations of a linear arrangement configuration. Graph showing the directional characteristics, FIG. 7 is an explanatory diagram showing the square arrangement in Comparative Example 2, FIG. 8 is a graph showing the directional characteristics in the case of the square arrangement, and FIG. 9 is the walking aid device for blind persons according to the present invention. FIG. 10 is an explanatory diagram showing the triangular arrangement of the embodiment; FIG. 11 is a circuit diagram showing the connection relationship between the ultrasonic transducer and the high-frequency power source; FIG. 12 is a graph showing the directional characteristics of the example. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Support ring, 3... Flexible vibrator, 4... Matching device, 10... Ultrasonic wave transmitting/receiving element.

Claims (1)

[Claims] 1 Bending type vibrators made of piezoelectric elements or piezoelectric elements and metal plates are arranged so as to be located at each vertex of a plurality of triangles, so that the bending vibration surfaces of each bending type vibrator are on the same plane. In the ultrasonic transducer, three of the bending type transducers are selected and electrically connected in parallel through a switch so as to be arranged at each vertex position of one triangle;
An ultrasonic transducer for a walking aid for a blind person, characterized in that a directional beam composed of three bending type transducers is scanned by switching the switch means.