JPH0456598A - Ultrasonic sensor - Google Patents

Abstract

PURPOSE:To obtain a prescribed directivity with a small sized sensor by selecting a start point of rising of a horn part to be a slope of a conical truncated cylinder of an ultrasonic wave microphone and differentiating the width of the opening of the horn in directions almost orthogonal to each other while passing through an axis center. CONSTITUTION:The ultrasonic sensor is provided with an ultrasonic microphone 11 whose tip is formed with a conical truncated cylinder and a microphone section 12 supporting the ultrasonic microphone 11 whose tip is formed with an opening and whose outer surrounding part of the conical truncated cylinder is formed with a cylindrical horn section 12C, at least part of a start point of rising of the horn section 12C is formed to be a slope of the conical truncated cylinder and the width of opening of the horn 12C is differentiated in directions almost orthogonal to each other while passing through the axis center of the ultrasonic wave microphone 11. Thus, one of the directivities almost orthogonal to each other is increased and the depth size is decreased, small size and thin profile are attained, the mount to a bumper side wall is facilitated, and a sensing area wider in the horizontal direction is obtained without mis-detection of a road face.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vehicle-mounted ultrasonic sensor that detects an obstacle in front of an ultrasonic microphone.

[Conventional technology]

As shown in FIGS. 9 and 10, a conventional ultrasonic sensor includes a microphone section 1 that intermittently transmits ultrasonic pulse signals and receives reflected waves from nearby obstacles;
A preamplifier section (which inputs a signal to the microphone section 1, processes the output signal of the microphone section 1, detects an obstacle, and outputs the signal to the display device)
(not shown). In this device, a microphone section 1 is provided on the upper surface of a bumper 5 of an automobile, and a preamplifier section is provided on the side of the automobile body. This microphone section 1 is an ultrasonic microphone 1
1, and a microphone holding member 12 that supports this and is held by a housing portion 13. Ultrasonic microphone 1
1, the tip portion is formed into a truncated conical shape. The microphone holding member 12 is formed into a cylindrical shape made of a rubber material, and has a groove portion 12b in the middle portion of the inner peripheral surface for holding the outer periphery including the truncated conical portion of the ultrasonic microphone 11. When the ultrasonic microphone 11 is installed in this groove 12b,
The tip surface of the ultrasonic microphone 11 and the microphone holding member 12
A horn portion 12c is formed between the end faces.

The microphone section 1 described above is provided on the upper surface of the bumper 5 of the automobile at an effective location where the road surface will not be detected erroneously.

[Problem to be solved by the invention]

Ultrasonic sensors such as those described above are not available in a variety of ways because the shape of the bumper and car body differs depending on the type of car.

For this reason, there has been a proposal to embed the microphone part in the side wall of the bumper so that it is less affected by the type of car. However, if the microphone section is lowered and placed at the front of the vehicle, there is a problem in that it may incorrectly detect the road surface because it does not have a predetermined directivity.

The present invention has been made in view of the above circumstances, and its purpose is to provide an ultrasonic sensor that can obtain a predetermined directivity with its current size.

[Means to solve the problem]

In order to achieve the above-mentioned object, the ultrasonic sensor of the present invention includes an ultrasonic microphone having a truncated conical tip, and a horn portion formed in front of the tip of the ultrasonic microphone. An ultrasonic sensor comprising: a microphone section having a microphone holding member; and a preamplifier section having a built-in preamplifier for processing signals of the ultrasonic microphone; It is said that

[Effect]

According to the present invention, directivity can be sharpened by making the tip portion of the ultrasonic microphone protrude into the horn portion.

[Example] Hereinafter, an example of the present invention will be described based on FIGS. 1 to 8. Substantially the same members as those in the conventional example described above will be described with the same reference numerals.

The main parts of the ultrasonic sensor of the present invention include a microphone section l and a preamplifier section 2.

The microphone section 1 includes an ultrasonic microphone 11 and a microphone holding member 12 held by a housing section 13. The ultrasonic microphone 11 is of an integrated transmission/delivery type that is driven by inputting a tone burst wave at a constant or arbitrary period to a piezoelectric element fixed to a vibration case lla, which will be described later. The vibration case lla is made of aluminum and is formed into a cylindrical shape with a bottom. This bottom portion 11b has a truncated conical portion 11c. The microphone holding member 12 is made of a vibration isolating material such as rubber and has a cylindrical shape, and has a retaining part 12a on the outer circumference that is engaged with the housing part 13, and an outer circumference of the ultrasonic microphone 11 on the middle part of the inner circumference. It has a groove portion 12b for holding, and a horn portion 12c formed between the groove portion 12b and the end face. This prevents the vibrations of the ultrasonic micropon 11 from being transmitted to the housing portion 13, which will be described later. The periphery of the groove portion 12d of the horn portion 12c is connected to the ultrasonic microphone 11.
When it is assembled, it touches the truncated conical portion 11c. As a result, the tip portion of the ultrasonic microphone 11 is made to protrude into the horn portion 12c. This ultrasonic microphone 1
If the amount of protrusion of the tip of 1 is increased, the result shown in Fig. 5 (
As shown in b), the directivity can be made sharp, and conversely, if it is made small,
Since it can be made wide as shown in FIG. 5(a), a predetermined directivity can be obtained by adjusting this.

Note that the amount of protrusion may be varied in orthogonal directions to obtain flat directivity. That is, when the axis of the microphone holding member 12 is positioned horizontally, the amount of protrusion is increased in the vertical direction to sharpen the directivity, and the amount of protrusion is increased in the horizontal direction (to make the directivity wider. The detection range of obstacles can be narrowed in the vertical direction as shown in FIG. 6(b) and widened in the horizontal direction as shown in FIG. 6(a).Also, as shown in FIGS. 3 and 4, A stepped portion 12d is provided at the periphery of the groove portion 12b of the horn portion 12c.This may provide flexibility to the periphery of the groove portion 12b and improve the adhesion between the ultrasonic microphone 1 and the horn portion 12c. 13 is formed into a cylindrical shape,
On one side, a flange portion 13a that fits into a through hole in the wall of the bumper 5 for positioning, and a first holding portion 13b that holds the engaging portion 12a of the microphone holding member 12, and on the other side, a 117th wire 41, and a first locking portion 13d that engages with the fixing means 3 on the outer surface of the intermediate portion. The flange 13a includes a first flange 13e that orients the microphone l with respect to the wall of the bumper 5, and a second flange 13f that engages with and orients the end of the microphone holding member 12. The first locking portions 13d are formed in a groove shape and are provided facing each other. Bumper 5 of this microphone section 1
Fixing to the wall is achieved by inserting the fixing means 3 into the wall of the bumper 5 from inside the wall of the bumper 5 when the housing part 13 is inserted into the through hole in the wall of the bumper 5 and the first flange part 13e comes into contact with the outer surface of the wall of the bumper 5. It is engaged with the first locking portion 13d.

The preamplifier section 2 includes a first lead wire 41 in a substantially rectangular box formed by an amplifier housing 21 and an amplifier cover 22.
It has a built-in preamplifier 23 to which a second lead wire 42 is connected. This box has a circumscribed circle diameter smaller than the circumscribed diameter of the cylindrical part of the housing part 13, and has a second locking part 21a that engages with the fixing means 3 on one side.

21a is provided. This one is 1. As shown in FIG. 7, the microphone section 1 is attached to a fixing means 3 to which it is fixed.

In the ultrasonic sensor as described above, the truncated conical portion 11c of the ultrasonic microphone 11 is made to protrude from the horn portion 12c, thereby improving the directional temperature characteristics. As a result, the conventional problem of erroneous detection due to variations in the detection range due to changes in directivity due to temperature has been resolved.

〔Effect of the invention〕

The ultrasonic sensor of the present invention has sharp directivity and eliminates false detection of the road surface, so it can be installed on the side wall of a bumper, and can be used in a variety of in-vehicle applications without the need for a large lineup. Compatible with cars.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing one embodiment of the present invention, and Fig. 2 is the same (, showing the main parts, (a) is a front view, (b)
is a cross-sectional view, (c) is a cross-sectional view, and Figure 3 is the same (, showing a modification of the main part, (a)
is a front view, (b) is a cross-sectional view, (c) is a cross-sectional view, and Figure 4 similarly shows a modified example of the main part. (a)
is a front view, (b) is a sectional view, (c) is a sectional view, and Figure 5 also shows the directional characteristics, where (a) is the horizontal directional pattern, and (b) is the vertical directional pattern. Characteristics, Figure 6 also shows the detection range, (a) is the detection range in the horizontal direction, (b) is the detection range in the vertical direction, and Figure 7 is a perspective view (with the bumper installed). , FIG. 8 is a perspective view of the external appearance (bumper is included), and FIG. 9 shows the main parts of the conventional example, (a) is a front view, (b) is a cross-sectional view, and FIG. 10 is a , also a perspective view of the exterior of the vehicle. 1-・Microphone section, it-Ultrasonic microphone, 12-
Microphone holding member, 13-housing part, 2-preamplifier part. Patent applicant Matsushita Electric Works Co., Ltd. agent Patent attorney Sato Sokomizu (1 idiot) No. 21
! I! (a) (C) Fig. 6 (a) (b) Chest 7 Fig. 114 Ca) (C') (b) Fig. 5 (a) (b) Chest 81II (a) 1') 12t) 11 Procedure Auxiliary equipment (voluntary) September 26, 1991

Claims (1)

[Claims] (1) An ultrasonic microphone having a truncated conical tip, a microphone holding member that holds the ultrasonic microphone and has a horn portion formed in front of the tip, and an ultrasonic microphone. An ultrasonic sensor comprising a preamplifier section having a built-in preamplifier for processing a signal, characterized in that a tip portion of the ultrasonic microphone protrudes from the horn section.