JP4213797B2 - Ultrasonic transducer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic transducer having a drip-proof structure that transmits and receives an ultrasonic frequency band.
[0002]
[Prior art]
A conventional ultrasonic transducer having a drip-proof structure will be described with reference to FIG.
In the figure, a piezoelectric element 2 is bonded with an adhesive 3 inside a bottom surface 6 of a bottomed cylindrical case to constitute a vibrating body. In this case, the bottom surface 6 of the bottomed cylindrical case to which the piezoelectric element 2 is bonded is formed with a uniform thickness.
[0003]
[Problems to be solved by the invention]
The conventional ultrasonic transducer with a drip-proof structure determines the frequency at which the transmission output and reception sensitivity are maximized by the area and thickness of the bottom surface of the bottomed cylindrical case, and the piezoelectric element to be bonded to that part. The directivity to be transmitted and received is determined based on the determined frequency and the area of the bottom surface of the bottomed cylindrical case. As shown in FIG. 4, this directivity characteristic has a conical characteristic centering on an axis that passes through the center of the bottom surface and is perpendicular to the bottom surface from the center of the bottom surface. In general, when the frequency is the same, when the area of the bottom surface constituting the vibrating body increases, the narrow directional characteristic is exhibited. When the area of the bottom surface constituting the vibrating body is the same, the narrow directivity characteristic increases when the frequency of the vibrating body increases. Indicates. Therefore, it is difficult to manufacture a drip-proof ultrasonic transducer having a narrow and narrow directivity in a 20 to 50 kHz drip-proof ultrasonic transducer with good air propagation. When the acoustic transducer is used for detecting an object such as a back sensor of an automobile, there is a problem in that reflection on the road surface is widened and accurate control cannot be performed.
[0004]
[Means for Solving the Problems]
On the bottom surface of the bottomed cylindrical case, a step d having a different thickness of the case is provided on the bottom surface to which the piezoelectric element is bonded, and the piezoelectric element is bonded to the thick side of the case. As a result, the directivity characteristics of transmission and reception can be tilted in an arbitrary direction. In addition, the level | step difference d of the thickness of the bottom face 4 of the said bottomed cylindrical case shall be set to the range of 0.05 mm-0.5 mm.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
As shown in FIG. 1, a piezoelectric element 2 is bonded with an adhesive 3 to the thicker side of the bottom of the bottomed cylindrical case 1 with different thicknesses to form a vibrating body. In this case, the thickness difference d of the bottom surface 4 of the bottomed cylindrical case is set to 0.1 mm. The conventional product is a target with respect to an axis perpendicular to the center of the bottom surface as shown in FIG. 4, but in the present invention, as shown in FIG. 3, it is inclined by θ with respect to an axis perpendicular to the center of the bottom surface. θ can be set in the range of about 5 to 20 degrees.
[0006]
【The invention's effect】
As described above, according to the ultrasonic transducer according to the embodiment of the present invention, by providing a step as a case thickness different from the thickness of the case on the bottom surface of the bottomed cylindrical case, by bonding the piezoelectric element, It is possible to incline the directivity for transmission and reception with respect to an axis passing through the center of the bottom case vertically. Therefore, when used as a back sensor of an automobile, the conventional product detects ground reflection as shown in FIG. 6 and accurate object detection control is impossible, whereas the present invention is shown in FIG. In this way, accurate object detection control is possible without being affected by ground reflection.
[Brief description of the drawings]
FIG. 1 is a schematic structural diagram of a main part of an ultrasonic transducer according to an embodiment of the present invention.
FIG. 2 is a schematic structural diagram of a main part of an ultrasonic transducer according to a conventional embodiment.
FIG. 3 is an explanatory diagram showing directivity characteristics of the ultrasonic transducer according to the embodiment of the present invention.
FIG. 4 is an explanatory diagram showing directivity characteristics of an ultrasonic transducer according to a conventional embodiment.
FIG. 5 is an explanatory diagram showing a detection area when the ultrasonic transducer according to the embodiment of the present invention is mounted on an automobile.
FIG. 6 is an explanatory diagram showing a detection area when an ultrasonic transducer according to a conventional embodiment is mounted on an automobile.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Bottomed cylindrical case 2 Piezoelectric element 3 Adhesive 4 Bottom surface of bottomed cylindrical case 5 Bottomed cylindrical case 6 Bottom surface of bottomed cylindrical case

Claims (1)

In an ultrasonic transducer that forms a vibrating body by laminating a piezoelectric element inside a bottomed cylindrical case and transmits and receives ultrasonic waves on the outer surface of the vibrating case, Steps d with different case thicknesses (steps d are in the range of 0.05 mm to 0.5 mm) are provided on the bottom surface to which the piezoelectric element of the cylindrical case is bonded, and piezoelectric is provided on the thicker case side. An ultrasonic wave transmitter / receiver characterized in that a directivity characteristic for transmitting and receiving is made asymmetric with respect to an axis perpendicular to the center of the bottom surface by bonding elements.

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