JPH0342635B2 - - Google Patents

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, ultrasonic waves are used as a means of detecting whether there is an obstacle behind the vehicle and the distance to the obstacle, and notifying the driver of the obstacle to ensure safety when backing up. An ultrasonic object detector using pulses is used.

As a means of transmitting and receiving ultrasonic signals in this ultrasonic object detector, the transmitting and receiving waves are transmitted from the transmitting transducer using dedicated transducers respectively, and the reflected waves from the reflecting object are transmitted. There are two methods: one is to receive the waves using a receiving transducer, and the other is to use 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 D is created at a short distance, and even if an object exists within this blind spot, it will not be detected, which is extremely dangerous. In order to eliminate such blind spots at short distances, it can be greatly improved by attaching three sensors S1, S2, and S3 to the rear of the vehicle P at regular intervals as shown in Figure 2. However, if this is done, a new problem arises in that the detection area at long distances becomes too wide.

(Object of the Invention) The present invention was made in view of the above problems, and its purpose is to reduce blind spots at short distances and to prevent the detection area from expanding at long distances. To provide an 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, detection area A is within 50 cm from the sensor, detection area B is is 50 from the sensor
cm or more and within 1m, detection area C is 1m from the sensor
The maximum distance is within 2m.

The center sensor S2 is designed to detect areas corresponding to detection areas A, B, and C, and the sensors S1 and S on both sides
3 detects only the areas corresponding to detection area A and detection area B, and the distance corresponding to detection area C.
Configure it so that it does not detect anything between 1m and 2m.

With this configuration, it is possible to secure a short distance area and a long distance area in the central sensor S2, and to secure the short distance blind spot in the sensors S1 and S3 on both sides.

FIG. 4 is a block diagram showing a circuit configuration for obtaining the above-mentioned detection area, in which a periodic oscillation circuit 1 outputs a timing signal every arbitrary or one period,
Based on this timing signal, the transmission pulse width generation circuit 2 creates a signal for controlling the oscillation circuit 3 corresponding to the transmission time, and the signal is amplified by the transmission amplification circuit 4, and then The voltage is applied to the oscillators 5, 6, and 7 corresponding to the oscillators 5, 6, and 7, respectively.
7 transmits an ultrasonic pulse signal. The transmitted ultrasonic pulse signal is reflected by a reflecting object,
The waves are received by the respective vibrators 5, 6, and 7 and converted into electrical signals. Since this signal has a very low level, 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 and 7 on both sides are connected to the second receiving amplifier 9. The received and amplified outputs are then detected by the first detection circuit 10 and the second detection circuit 11 and converted into digital signals.
0 outputs a converted signal of the signal from the central vibrator 6, and the second detection circuit 11 outputs a converted signal of the signals from the vibrators 5 and 7 on both sides.

The gate signal creation circuit 12 creates a time gate corresponding to the detection distance. These outputs a, b, and c are gates corresponding 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 gate signal generation circuit 12, outputs a detection signal, and outputs a detection signal. Judgment circuit 1
4 is configured so that the output of the second detection circuit 11 is determined in the same manner as described above and outputs a detection signal. The output signal generation circuit 15 selects how to output the alarm device 16 consisting of a buzzer, a lamp, etc. in the next stage, depending on the output state of each judgment circuit 13, 14 in the previous stage.

(Effects of the Invention) As described above, the present invention provides ultrasonic object detection 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. The device is characterized in that the detection distance of the vibrator installed in the center is longer than the detection distance of the vibrators installed on both sides, so it is possible to detect short distances without expanding the overall detection area at long distances. Can be made wider. Therefore, it was possible to provide a sonic object detector 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, and FIG. 3 is a diagram showing the relationship between the sensor position and the detection area according to the present invention.
FIG. 4 is a block diagram showing a circuit configuration for obtaining the above detection area.

Claims (1)

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