JPH0114947Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a rear obstacle detection device for a vehicle that detects obstacles behind the vehicle by transmitting and receiving ultrasonic pulses.

As shown in Fig. 1, the conventional rear obstacle detection device is equipped with two sets of transducers, a transmitter 2 and a receiver 3, at the rear of a vehicle 1, and transmits ultrasonic pulses to the rear. It was designed to detect the presence or absence of an obstacle by emitting waves reflected from the obstacle and issue a warning to the driver.
In this case, the obstacle detection range A is determined to be a detection width M ₀ that is approximately the same as the vehicle width. This is because if the detection width M ₀ is equal to or larger than the vehicle width, there will be a problem in which objects that do not pose an obstacle to the vehicle will be detected when the vehicle is traveling straight backwards.

However, if the above-mentioned obstacle detection range A is a detection width M ₀ that is approximately the same as the vehicle width, when turning backward right, that is, moving backward in the direction of arrow R, or turning backward left, that is, arrow L
When reversing in a direction, there was a drawback that an obstacle X on the curved reversing path could not be detected.

The present invention was devised in view of the above-mentioned drawbacks, and its purpose is to detect the direction of the vehicle's tires and change the rear obstacle detection range in accordance with the direction of the tires. Obstacles on a curved back road can be detected only when turning left,
The purpose is to improve safety when the vehicle is reversing.

A preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a block circuit diagram of a vehicle rear obstacle detection device, in which one set is provided for the right side of the vehicle and one set for the left side of the rear of the vehicle. Incidentally, FIG. 2 shows a set of rear obstacle detection devices for a vehicle. Second
In the figure, 4 is an oscillation circuit that generates a constant frequency, and 5
6 is a monostable multivibrator operated by the output of the oscillation circuit 4, and 6 is a monostable multivibrator 5.
2 is a transmitter that emits ultrasonic pulses using the output of the amplifier circuit 6; 3 is a transmitter that receives the reflected waves of the ultrasonic pulses emitted by the transmitter 2 and reflected by the obstacle 7; 8 is an amplifier circuit that amplifies the output of the wave receiver 3; 9 is a detection circuit that detects the reflected wave from the obstacle 7 by detecting the output of the amplifier circuit 8; 10 is the detection circuit 9; A second comparator circuit 11 compares whether the output value exceeds a reference level, and 11 determines whether the output of the second comparator circuit 10 is inputted at a predetermined delay time after being output to the oscillator circuit 4, and determines the judgment result.
If YES, the judgment circuit activates the alarm 12. The transmitter 2 and the receiver 3 are installed at the rear of the vehicle 1 as shown in FIG. 1, and the alarm 12 is installed near the driver.

Reference numeral 13 denotes a tire direction sensor that detects the direction of the tires of the vehicle, for example, corresponds to the operation of a steering wheel or a steering mechanism, and outputs an electric signal according to the angle at which the tires are facing. 14 is a first comparison circuit that outputs an output when the output of the tire direction sensor 13 changes by more than a predetermined value. The second comparison circuit 10 described above compares whether the output value of the detection circuit 9 exceeds a reference level that changes based on the output of the first comparison circuit 14, and outputs a high level output if it exceeds the reference level. A detailed circuit example of the tire direction sensor 13, the first comparison circuit 14, and the second comparison circuit 10 will be explained with reference to FIG. In FIG. 3, +B indicates the positive pole of the DC power supply. In the tire direction sensor 13, 13a is a variable resistor that is linked to the tire direction, and one end is connected to the positive terminal +B of a DC power source,
The other end is connected to ground. First comparison circuit 14
, 14a is a comparator, whose inverting input side is connected to a reference voltage circuit composed of two resistors 14b and 14c, and its non-inverting input side is connected to the variable resistor 1 described above.
3a, respectively. Second comparison circuit 10
10a is an analog switch connected to the output side of the comparator 14a. Also,
10b is a comparator, and the inverting input side is a reference voltage circuit composed of two resistors 10c and 10d;
and analog switch 10 via resistor 10e.
a, and the non-inverting input side is connected to a terminal 10g via a resistor 10f. Further, the output side of the comparator 10b is connected to the terminal 10h. In the second comparator 10, a terminal 10g is connected to the output side of the detection circuit 9, and a terminal 10h is connected to the input side of the determination circuit 11. Furthermore, comparator 1
The output side and the non-inverting side of the comparator 4a and the comparator 10b are connected through a resistor 14d and a resistor 10i, respectively, to form a positive feedback circuit to prevent the influence of noise voltage. Next, the operation will be explained based on the above configuration.

When traveling straight backward, the monostable multivibrator 5 is activated by the constant frequency output from the oscillation circuit 4.
is shaped into a predetermined pulse width, the amplifier circuit 6 amplifies the output, and the transmitter 2 emits it as an ultrasonic pulse to the rear of the vehicle 1. When the ultrasonic pulse emitted by the transmitter 2 is reflected by the obstacle 7, the receiver 3
It receives the reflected wave and converts it into an electrical signal. The amplifier circuit 8 amplifies the electric signal, the detection circuit 9 detects the output, and the second comparison circuit 10 compares whether the output value of the detection circuit 9 exceeds a reference level that changes based on the tire direction. and outputs a high level. After the output of the oscillation circuit 4, the determination circuit 11 determines whether the input is received from the second comparator circuit 10 after a predetermined delay time, and if the determination result is YES, activates the alarm 12 to notify the driver of the obstacle behind the vehicle 1. Alerts the existence of object 7.

Incidentally, the output potential of the tire direction sensor 13 increases as the angle at which the tire faces becomes wider. However, the vehicle rear obstacle detection device shown in FIGS. One set has been deployed. Therefore, the tire direction sensor 1 for right side deployment
3, the output potential increases when the vehicle 1 performs a rear right turn operation, and the tire direction sensor 1 is installed on the left side.
3, the output potential increases due to a backward left turn operation. Thus, the comparators 14a of both the left and right first comparison circuits 14 are connected to the corresponding tire direction sensor 1.
When the output potential of No. 3 exceeds a predetermined value, the non-inverting input side potential exceeds the inverting side potential, and if the output is set as high as possible, the output will be low level when traveling straight backwards. At this time, in the second comparison circuit 10, the analog switch 10a is OFF, so
The comparator 10b has the detection circuit 9 output at the terminal 10.
When the non-inverting input potential input through g exceeds the inverting input potential, a high level output is output to the determination circuit via the terminal 10h. In this case, the obstacle detection ranges of the two sets of left and right vehicle rear obstacle detection devices are A shown in FIG. After that, when making a rear right turn with the tire direction at a predetermined angle or more, the output potential of the tire direction sensor 13 installed on the rear right side of the vehicle 1 increases and the output of the comparator 14a becomes a high level, so the analog switch 10a is turned ON.
do. Then, the reference potential at the inverting input side of the comparator 10b decreases, so the detection circuit 9
Even if the output is at a relatively low potential, it will be a high level output. Therefore, the comparator 10b becomes highly sensitive, and the obstacle detection ranges of the two sets of left and right vehicle rear obstacle detection devices are in addition to the range A shown in FIG. 1, the range B where the detection width is _M1 . It becomes wide-ranging,
Obstacle X in FIG. 1 can also be detected.

On the other hand, when making a rear left turn, due to the same operation as above, the obstacle detection range of the two sets of left and right vehicle rear obstacle detection devices is the range A shown in Figure 1, and the detection width is set to _M2 . The area becomes wider by the area C.

In the above embodiment, one alarm device 12 may serve as the left and right vehicle rear obstacle detection devices.

Furthermore, one tire direction sensor can be used for both left and right sides, and in that case, a dual power supply system is used, with one end of the variable resistor 13a connected to the positive terminal +B of one DC power supply, and the other end connected to the positive terminal +B of the other DC power supply. The comparators 14a of the left and right first comparator circuits 14 may be connected to the variable terminals of the variable resistor 13a in a reverse connection to that in FIG. 3, respectively.

Since it has the above structure and operation, the following effects are achieved.

In other words, by providing the second comparison section, the activation level of the alarm can be varied according to the angle at which the tire is facing. Therefore, for example, the wider the angle at which the tire is facing, the more the alarm is activated for low-level reflected waves. This makes it easier for the device to operate, and when making a rear right turn or rear left turn, it is possible to detect obstacles on a curved retreat road where the reflected waves are at a low level and issue a warning, improving safety when reversing.

[Brief explanation of the drawing]

1 to 3 show an embodiment of the rear obstacle detection device for a vehicle according to the present invention, in which FIG. 1 is a plan view of the device installed in a vehicle, FIG. 2 is a block circuit diagram, and FIG. 3 is a block diagram. 2 is a detailed circuit diagram of the tire direction sensor, the first comparison circuit, and the second comparison circuit in FIG. 2. FIG. 2... Wave transmitter, 3... Wave receiver, 10... Second comparison circuit, 13... Tire direction sensor, 14... First comparison circuit.

Claims (1)

[Scope of utility model registration request] In a vehicle rear obstacle detection device that emits ultrasonic pulses to the rear of the vehicle and receives reflected pulses from obstacles to issue an alarm, a tire direction sensor detects the direction of the vehicle's tires and outputs an output corresponding to that direction. a first comparison section that outputs an output when the output of the tire direction sensor changes by more than a predetermined value; and a second comparison section that changes the obstacle detection range by varying a reference level based on the output of the first comparison section. A vehicle rear obstacle detection device characterized by: