JPH0312268B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an ultrasonic sensor that detects obstacles around a vehicle using an ultrasonic transducer.

[Background technology]

Generally, ultrasonic sensors have a cylindrical horn attached to the tip to improve directivity, which narrows the detection area and makes it difficult to detect a wide area around the vehicle with a single ultrasonic sensor. It was hot. In view of this point, for example, Japanese Patent Application Laid-open No.
As shown in Publication No. 54878, there are some devices that use multiple ultrasonic sensors to widen the detection range, but the detection area of the ultrasonic sensor is narrow near the horn and gradually decreases as you move away from the horn. Because it is formed to be wide, it can detect a wide range of obstacles at a distance from the horn, but the area immediately next to the horn becomes a blind spot and cannot detect obstacles.
In particular, if there are small obstacles such as children in this area, it is difficult for the driver to visually check the area, which is extremely dangerous.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an ultrasonic sensor for a vehicle that eliminates blind spots of the ultrasonic sensor and improves safety.

[Disclosure of the invention]

(Example) Examples of the present invention will be described below with reference to FIGS. 1 to 3 of the drawings. Reference numeral 1 denotes a mounting base such as a vehicle bumper, on which three ultrasonic transducers 2, 3, and 4 are fixed with screws at equal intervals (dimension l in the figure). The transducers 2, 3, and 4 each include a horn 7 that houses a microphone 6 through a cushion body 5 for preventing reverberation at its base, and a housing part 8 that houses electric components (not shown) such as a head amplifier. and is connected to a control circuit 10 via a lead wire 9. The horn 7 is cylindrical and has an oval tip that is elongated in the vertical direction.The oval tip narrows the detection area in the vertical direction to prevent false detection of the ground. The horn 7 protrudes from the mounting base 1, and the horn 6 of the central transducer 3 is formed with small holes 11, 11 opening laterally on both side walls thereof, as shown in FIG. Thus, ultrasonic waves are transmitted not only from the tip of the horn 7 but also from the small hole 11, so that obstacles located immediately adjacent to the horn 7 can be detected. Further, the small hole 11 is formed into an oval shape that is elongated in the axial direction of the horn 7, so that the detection area is shortened in the axial direction so that the mounting base 1 is not detected incorrectly. If the opening area of the small hole becomes large, it will affect the transmission of waves from the horn 7, but if the opening area is small, the influence on the transmission of waves from the horn 7 can be suppressed. It is. Since it is assumed that a hole is formed in the side wall of the horn, the shape of the horn is determined while taking into consideration the influence of the small hole formed.
In other words, the shape of the ultrasonic beam that forms the object detection area is determined by the shape of the horn and the shape and size of the small hole opened in the side wall of the horn. Its shape and size are appropriately determined in accordance with the shape of.

(Operation) Next, the operation of the embodiment of the present invention will be explained based on FIGS. 1 and 4 to 7. The circuit is as shown in FIG. Transmitter/receiver 2 for transmitting sound wave pulses,
3 and 4, the reflected waves from obstacles are also received by the transducers 2, 3, and 4, and the respective received signals are amplified by amplifiers 15, 16, and 17 to increase the level. It is input to detectors 18, 19, and 20. The waveforms of the transmitting signals from the transducers 2, 3, and 4 are shown in FIG. 5, 2A, 3.
A, 4A, and the output waveforms from the amplifiers 15, 16, and 17 when there are no obstacles are shown in Figure 5.2.
Shown in B, 3B, and 4B. Amplifier 15, 16, 17
The output waveform has a reverberation component E and a wraparound component F from an adjacent transducer. The level detectors 18, 19, 20 and gate circuit 21
is to detect the wraparound component F, and if there is a wraparound component F of a certain level or higher within the time set by the gate circuit 21, the waveform shaping circuit 22, 2
3, 24 and AND circuits 25, 26, the signal is input to the display 26, and a buzzer, lamp, etc., indicates the fact. If this display is present,
All ultrasonic sensors are working properly.
This shows that there are no failures such as disconnections.

In addition, as shown in FIG. 1, when an obstacle G exists within the detection area of the transducer 3, an ultrasonic pulse is transmitted from the small hole 11 of the horn 7, and Multiple reflections occur. The output waveform from the amplifier 16 at this time is shown in FIG. 6B. The signal from the amplifier 16 is input to an AND circuit 31 via an OR circuit 28, a level detector 29, and a waveform shaping circuit 30, and is input to an AND circuit 31 as shown in FIG. 6C.
If there is a reflected signal of a certain level or higher within the time t set in step 2, the detection signal shown in FIG. It shows what to do.

Furthermore, as shown in FIG. 1, when an obstacle H exists, the output waveform from the amplifier 16 becomes as shown in FIG. 7B, and the time ( If there is a reflected signal of a certain level or higher within the time t) shown in FIG. 7C, a detection signal shown in FIG. 7D is output from the AND circuit 31, and the display 33 indicates the presence of an obstacle. . The level detector 29 is connected to the level detector 18,
The threshold is set lower than that of the small holes 11 and 20, and if there is a component above a certain level within the time set by the gate circuit 32, it is detected, and even a slight reflection can be detected. It detects reflected waves from

〔Effect of the invention〕

As described above, the present invention provides an ultrasonic sensor for a vehicle that detects reflected waves from obstacles around the vehicle by attaching an ultrasonic transducer to a vehicle, and which comprises a cylindrical horn of the ultrasonic transducer. Since the horn is provided to protrude from the mounting base of the vehicle, and a small hole is formed in the side wall of the horn, obstacles in the area immediately adjacent to the horn, which was a blind spot in the past, can be reliably detected, improving safety. It will improve.

[Brief explanation of the drawing]

Fig. 1 is a top view showing an embodiment of the present invention, Fig. 2 is an external perspective view of the above transducer, Fig. 3 is a sectional view of the above transducer, and Fig. 4 is a circuit block diagram of the same. , Fig. 5 shows the output waveform diagram when there is no obstacle, and 2A, 3A, 4A are the transducers 2, 3,
4, 2B, 3B, and 4B are output waveform diagrams of each of the amplifiers 15, 16, and 17, and FIGS. 6 and 7 are output waveform diagrams when an obstacle exists, A is an output waveform diagram of the transducer 3, B is an output waveform diagram of the amplifier 16, C is an output waveform diagram of the gate circuit 32, and D is an output waveform diagram of the AND circuit 31. 1... Mounting base, 2, 3, 4... Transducer/receiver, 7
...Horn, 11...Small hole, G, H...Obstacle.

Claims (1)

[Scope of Claims] 1. An ultrasonic sensor for a vehicle in which an ultrasonic transducer is attached to a vehicle and detects reflected waves from obstacles in the middle of the vehicle, the ultrasonic transducer having a cylindrical shape. An ultrasonic sensor for a vehicle, characterized in that a horn is provided to protrude from a mounting base of a vehicle, and a small hole is formed in a side wall of the horn. 2. The ultrasonic sensor for a vehicle according to claim 1, wherein small openings are formed on both side walls of the horn. 3. The ultrasonic sensor for a vehicle according to claim 1, wherein the opening small hole has an oval shape that is elongated in the axial direction of the horn.