JPS59214786A - Ultrasonic object detector - Google Patents

Abstract

PURPOSE:To prevent the expansion of the detection area at a long range while minimizing the dead angle in a short range by making the detection distance of a vibrator provided at the center longer than the detection distance of a vibrator provided at both ends. CONSTITUTION:A sensor S2 at the center detects the area corresponding to the detection areas A, B and C while a sensor S1 and a sensor S3 at both ends detect the area corresponding to the detection areas A and B only, not the disstance corresponding to the detection area C. This enables the sensor S2 at the center to secure the areas at the short and long ranges while the sensor S1 and the sensor S3 to secure the dead angle at the short range.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an ultrasonic object detector that detects obstacles existing behind a vehicle, for example.

(Background technology) When a vehicle backs up, it detects whether there is an obstacle behind it and how far it is to the obstacle, and notifies the driver of the problem, thereby ensuring safety when backing up.
Ultrasonic object detectors using ultrasonic pulses are used.

As a means of transmitting and receiving ultrasonic signals in an ultrasonic object detector, the transmitting and receiving waves are transmitted from a transmitting transducer using a dedicated transducer, and the waves are reflected from a reflecting object. There are two methods: one method uses a receiving transducer to receive the waves, and the other uses the same ultrasonic transducer for transmitting and receiving waves.

The former method has the drawback that it requires a large number of transducers and cannot detect a reflective object near the front of the transmitting transducer or receiving transducer, so the latter method is also used. .

However, in the latter method, the detection area is narrow in the vicinity and widen in the distance, so when this method is used for a vehicle rear monitoring device, the sensor S is attached to the center of the rear of the vehicle P, as shown in Figure 1. In this case, a large blind spot is created at close range, and even if objects exist within this blind spot, they are not detected, which is extremely dangerous. In order to eliminate such blind spots at short distances, three sensors S1. S2. Although a significant improvement can be achieved by attaching the S3s at regular intervals to the rear of the vehicle P, doing so causes a new problem in that the detection area at the speed ratio nl becomes too wide.

(Objective of the Invention) The present invention has been made in view of the above-mentioned problems, and its purpose is to reduce blind spots at short distances and prevent the detection area from expanding at long distances. To provide a sonic object detector.

(Disclosure of the Invention) FIG. 3 shows the relationship between the sensor position and the detection area according to the present invention. The detection area is divided into three in the distance direction. For example, the detection area Δ is within 5Qcm from the sensor,
Detection area B is within 5Qcm or more lm from the sensor,
The detection area C is within 1 m and 2 m above the sensor.

Therefore, in the central sensor S2, the detection area A,
It is designed to detect areas corresponding to B and C, and sensors S1 and S3 on both sides detect only detection area 8 and an area corresponding to detection area B, and a distance corresponding to detection area C! Tilt 1m or more and 2m or less are configured so as not to be detected.

With this configuration, the central sensor S2 secures a short-range area and a long-range area, and the sensors S2 on both sides
1 and sensor S3, the short-range blind spot can be secured.

FIG. 4 is a block diagram showing a circuit configuration for obtaining the above-mentioned detection area.The periodic oscillation circuit 1 outputs a timing signal at arbitrary or fixed intervals, and this timing signal is used to create a transmission pulse width. ? & 2, a signal for controlling the oscillation circuit 3 corresponding to the transmission time is created, amplified by the transmission amplifier circuit 4, and transmitted to each of the sensors 9-3IS2. The voltage is applied to the oscillators 5 and 6.7 corresponding to S3, respectively, and each oscillator 5
．． 6. Transmit an ultrasonic pulse signal from 7. The transmitted ultrasonic pulse signal is reflected by the reflecting object, received by each of the transducers 5, 6.7, and converted into an electrical signal. Since this signal has a low level compared to the egg weight, it is amplified by the first receiving amplifier 8 and the second receiving amplifier 9.

At this time, the central vibrator 6 is connected to the first receiving amplifier 8, and the vibrators 5.7 on both sides are connected to the second receiving amplifier 9. Then, each received wave amplification output is the first one.
is detected by the detection circuit lO and the second detection circuit 11,
The first detection circuit 10 outputs the converted signal from the center transducer 6, and the second detection circuit 11 outputs the converted signal from the transducers 5.7 on both sides. A signal is output.

The data 1 signal generation circuit 12 generates a time gate corresponding to the detected pressure All. These outputs a, b, and c correspond to the detection areas A, B, and C, respectively. The first determination circuit 13 determines in which area the output of the first detection circuit 10 exists based on the gate output signal of the Goo 1 signal generation circuit 12, outputs a detection signal, and outputs a detection signal.
The determination circuit 14 is configured to determine the output of the second detection circuit 11 in the same manner as described above and output a detection signal. The output signal generation circuit 15 includes each of the preceding stage determination circuits 13 .
Depending on the output state of the alarm 14, the output of the next-stage alarm device 16, such as a buzzer or a lamp, is selected.

(Effects of the Invention) As described above, the present invention provides an ultrasonic object in which at least three ultrasonic transducers for transmitting and receiving waves are arranged in parallel at approximately equal intervals, and a plurality of detection areas are set in the same direction. In the detector,
It is characterized in that the detection pressure All of the vibrator provided in the center is longer than the detection distance of the vibrators provided on both sides.
It is possible to widen the short range 1i11 without expanding the entire detection area at long distances. Therefore, it has been possible to provide a sonic object detection device that has fewer blind spots at short distances and can prevent the detection area from expanding at long distances.

[Brief explanation of drawings]

1 and 2 are diagrams showing the relationship between the sensor position and the detection area according to the conventional example, FIG. 3 is a diagram showing the relationship between the sensor position and the detection area according to the present invention, and FIG. 4 is a diagram showing the relationship between the sensor position and the detection area according to the present invention. FIG. Patent applicant Matsushita Electric Works Co., Ltd. Agent Patent attorney Toshimaru Takemoto (and 2 others)

Claims (1)

[Claims] (1) In an ultrasonic object detector consisting of at least three ultrasonic transducers for both transmitting and receiving waves arranged at approximately equal intervals and multiple detection areas set in the same direction, the vibration installed in the center An ultrasonic object detector characterized in that the detection distance of a child is longer than the detection distance of transducers provided on both sides.