JPH0516537Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an obstacle detection device for a vehicle that detects obstacles using reflected waves of ultrasonic waves.

(Prior Art) Traditionally, vehicle obstacle detection devices that are mounted on automobiles and used to detect obstacles have been used for their intended purpose, and if the circuits inside the device should become abnormal, it would pose a great danger. Before operation, it is necessary to check whether the equipment is working properly.

Conventionally, in vehicle obstacle detection devices that use reflection-type ultrasonic sensors, the reverberation that occurs when the sensor's microphone is driven by an electrical signal, that is, the microphone remains unreverberated for a certain period of time even after the driving electrical signal is removed. The presence or absence of an electrical signal generated to continue the vibration was detected, and if the reverberation continued for a certain period of time, the control circuit within the device determined that the sensor system was normal.

However, the reverberation component has poor stability because the generation time etc. changes depending on the temperature, and the reverberation component has poor stability.
It tends to be unreliable when used as a signal source for determining abnormalities.

Furthermore, a device has been proposed that uses the presence or absence of reflected waves from reflective objects other than obstacles to detect abnormalities in the detection device. For example, a configuration in which a plurality of transducers are arranged and an opening for lateral detection is provided in the side wall of the central transducer horn so that wraparound waves can be detected simultaneously (Japanese Patent Application Laid-Open No. 1983-1992-1)
126487), a lid that can be opened and closed is provided at the tip of the horn, and when detecting an abnormality, this lid is closed.
On the other hand, when detecting an obstacle, a device with a structure that can be rotated so as to be opened (see U.S. Pat. A system has been proposed in which an abnormality is detected based on the presence or absence of reflected waves from the road surface (Japanese Unexamined Patent Publication No. 175266/1983).

However, the devices described in the above-mentioned conventional publications all have a configuration in which a reflective object for abnormality detection is provided within the obstacle detection range (detection area), so due to this configuration, the following problems occur. This is causing problems. In other words, in the device described in JP-A No. 61-126487, the lateral direction of the central transducer is also the original detection area, so if there is a wraparound wave from here, it is necessary to approach the position in this direction. In order to detect such an obstacle in a way that it can be distinguished from the above-mentioned wrap-around wave, special signal processing is inevitably required, and the signal processing circuit becomes complicated. Also, Utility Model Application No. 59-151173, Utility Model Application No. 59-151172
The method described in the publication requires a lid and a lid opening/closing structure, and the operator is forced to open and close the lid each time, which may be extremely dangerous or frequent work depending on the installation position of the detection device. As expected, it lacks practicality. In addition, Tokukai Akira
The device described in Publication No. 57-175266 always includes a road surface signal in the detection signal, making it impossible to detect obstacles from a distance in front equal to the road surface distance. This will increase the risk. This point is explained in the above-mentioned JP-A-61-
In Japanese Patent No. 126487, a similar problem exists with respect to reflected waves and wraparound waves from front obstacles.

(Purpose of the invention) The present invention solves the above-mentioned technical problems, makes it possible to detect and judge whether the device is normal or abnormal with a simple configuration by using the outside of the detection area, and also enables reliable obstacle detection. The object of the present invention is to provide a vehicle obstacle detection device that enables the following.

(Structure of the invention) The present invention is a vehicle that transmits ultrasonic waves from a microphone having an ultrasonic horn toward the front of the horn, receives reflected waves from obstacles in front of the vehicle, and detects the presence or absence of obstacles. In the obstacle detection device for the ultrasonic horn, a reflecting plate is provided in close proximity to face one leak hole formed in the side wall of the ultrasonic horn, and the presence or absence of reflected waves from this reflecting plate is detected, and the presence or absence of reflected waves is detected. It has an abnormality warning means that warns that there is an abnormality.

With this configuration, a portion of the transmitted ultrasonic waves leaks from the leakage port, is reflected by the reflector, returns to the horn, and is received. This confirms that the device is normal. On the other hand, if there is no return wave, it is determined that there is an abnormality. At this time, the distance between the reflector and the tip of the ultrasonic horn is not much different or is closer, so the reflector can be seen as being outside the detection area and does not pose any problem in detecting obstacles. .

(Example) FIG. 1 is a perspective view of a vehicle obstacle detection device according to an embodiment of the present invention, FIG. 2 is a sectional view of an ultrasonic horn of the vehicle obstacle detection device, and FIG. FIG. 1 is a partial side view of an automobile to which a vehicle obstacle detection device is attached.

1 to 3, the vehicle obstacle detection device A of this embodiment is roughly divided into an ultrasonic horn B and a casing C housing a circuit described later.
and a reflecting plate D, which is a feature of the present invention. The reflecting plate D faces an opening E formed in the side wall of the ultrasonic horn B, and is fixed to the casing C. The vehicle obstacle detection device A having such a configuration is attached to a bumper G of a vehicle body F of an automobile.

FIG. 4 is a block diagram of a detection circuit provided within the casing C of the vehicle obstacle detection device A.

In FIG. 4, an integrating circuit 1 starts an integrating operation as soon as the power is turned on, and after a certain period of time has passed, when it reaches a threshold level, it outputs a trigger signal to drive a monostable multivalve circuit 2. This monostable multivibrator circuit 2 receives a trigger signal from the integrating circuit 1, applies a signal to the differentiating circuit 3 for a certain period of time, and resets the integrating circuit 1. The differentiating circuit 3 differentiates the rising edge of the signal waveform output from the monostable multivibrator circuit 2. The monostable multivibrator circuit 4 provides a signal to the oscillation circuit 5 for a certain period of time based on the differentiated signal from the differentiator circuit 3. The oscillation circuit 5 generates a high frequency signal for driving the microphone of the transducer 7 for a period of time given by the output of the monostable multivibrator circuit 4. The drive circuit 6 amplifies the high frequency signal from the oscillation circuit 5, which is generated for a given time by the output of the monostable multivibrator circuit 4, and drives the microphone of the transducer 7.

The transducer 7 is equipped with the above-mentioned ultrasonic horn B and the above-mentioned microphone, and outputs the high frequency signal from the drive circuit 6 as an ultrasonic wave to the outside, and also outputs the ultrasonic wave through a reflection plate through the ultrasonic horn B. The signal is applied to the microphone, converted into an electrical signal, and applied to the amplifier circuit 8.

The amplifier circuit 8 is for amplifying a minute electrical signal from the microphone. The detection circuit 9 is
High frequency components and levels lower than 0 are removed from the amplified electrical signal to extract only the wave envelope. A level detection circuit (including the function of an abnormality warning means) 10 detects the level of the detected signal and removes waves below a predetermined threshold level. The gate circuit 11 is a circuit for determining whether a transducer input signal exceeding a threshold level has entered the level detection circuit 10 within a predetermined time. Note that if the gate time by the gate circuit 11 is changed, the detection distance changes. Further, this gate circuit 11 is triggered by the output of the monostable multivibrator circuit 2, and operates with a momentary delay from the time when the output of the monostable multivibrator circuit 2 is generated, and operates while the timer circuit 13 is operating. I've learned not to. This gate circuit 11 is used to determine the presence or absence of a reflected wave detection input.

Gate circuit (including the function of abnormality alarm means) 12
is triggered by the output of the monostable multivibrator circuit 2, similar to the gate circuit 11, and opens the gate for a certain period of time a moment after the output of the monostable multivibrator circuit 2, and the timer circuit 13
While working, it is triggered by the output of the monostable multivibrator circuit 2 and repeats the output of the gate signal. This gate circuit 12 is for detecting the presence or absence of a reflected wave from the opening E of the ultrasonic horn B, that is, a signal for detecting an abnormality such as a circuit break. The timer circuit 13 determines the time for detecting whether the device is normal or abnormal.
While this timer circuit 13 is working, the gate of the gate circuit 12 is repeatedly opened, but the gate circuit 11
The gate remains closed.

The memory circuit 14 forcibly operates the display circuit 15 if there is no reflected input from the reflection plate D while the gate circuit 12 is operating, and causes the display 16 to indicate an abnormality in the apparatus. The display device (including abnormality warning means) 16 is driven by the output of the display circuit 15, and displays the distance to the driver and the abnormality of the device as described above.

FIG. 5 shows a timing chart for explaining the operation when the vehicle obstacle detection device A is operating normally, and FIG. 6 shows the operation when the detection device A becomes abnormal. This shows the flowchart for

The operation of this vehicle obstacle detection device A will be explained with reference to FIGS. 5 and 6.

When the power is turned on to the detection device A, the timer circuit 13 and the integration circuit 1 start operating, and after a certain integration time has elapsed, the transmission signal P1 (FIG. 5a) is transmitted and received via the drive circuit 6. 7 and is emitted into the air from an ultrasonic horn B as an ultrasonic wave.
At this time, most of the ultrasonic components emitted from the ultrasonic horn B are emitted from the tip of the horn-shaped ultrasonic horn B, but some of them leak from the opening E and are reflected by the reflector D, causing the ultrasonic waves to It returns to the horn B microphone. As a result, the amplifier circuit 8 outputs a reverberation signal P2 as a transmission signal as shown in FIG. 5b.
, a reflected signal P3 from the reflecting plate D, and a reflected signal P4 from the sensing object H are output, and these signals P2,
P3 and P4 are detected by the detection circuit 9 and become a detected reverberation signal P5, a detected reflection plate signal P6, and a detected object reflection signal P7. Here, the level detection circuit 10
In order to confirm the reception of the reflected wave from the aperture E (the detection reflection plate reflection signal P6), the signal of the threshold level V or higher (in this case, at least the detection reflection plate signal P6) is detected by the gate circuit 12. It is checked whether the time period during which the gate is open is within the time width T1 of the gate signal P8 as shown in FIG. 5d. Therefore, as shown in FIG. 5c, the detected reverberation signal P above the threshold level V
5 and the detected reflection plate reflection signal P6 are within the time width T1, the level detection circuit 10 detects the reverberation component signal P9 and the reflection plate reflection component signal P10 as shown in FIG. 5e.
Outputs . At this time, the memory circuit 14 remains canceled and the display circuit 15 is not operated, so that no abnormality is displayed on the display 16.

However, some abnormality occurs in the detection device A, and the ultrasonic waves are not reflected from the ultrasonic horn B. As a result, there is no reflected wave from the reflection plate D, and the output of the amplifier circuit 8 becomes as shown in FIG. 6a. Reverberation signal P
There will only be 2. Accordingly, the output of the detection circuit 9 becomes only the detected reverberation signal P5 as shown in FIG. 6b. In such a state, the level detection circuit 10
As described above, it is checked whether a signal equal to or higher than the threshold level V exists within the time width T1 of the gate signal P8. In this case, as shown in FIG. 6, since there is no signal equal to or higher than the threshold level V within the time width T1, the level detection circuit 10 does not give a signal to the memory circuit 14, and therefore the memory circuit 14 is connected to the display circuit. 15 is forced into operation, and an abnormality is displayed on the display 16.

In the level detection circuit 10, the gate circuit 12
The confirmation of the reflected wave from the opening E by the gate signal P8 from the timer circuit 13 is not performed when the timer time of the timer circuit 13 ends.
If the fifth circuit 1 operates and there is a reflected wave from the detected object H, the display circuit 15 is put into a normal operating state (for example, an operation to display the object detection distance).
The detected object reflected signal P4 from the amplifier circuit 8 as shown in FIG.

Note that the opening E in the above embodiment is an ultrasonic horn B.
It can also be used to drain water when rainwater etc. enters the tank.

(Effects of the invention) As described above, according to the invention, the ultrasonic waves from one leakage port formed in the side wall of the ultrasonic horn are stabilized by the reflection plate provided close to and facing the leakage port. Since the returned reflected waves return to the ultrasonic horn as reflected waves, the presence or absence of these returned reflected waves can be reliably detected, and therefore, highly reliable confirmation of normality and abnormality can be performed with a simple configuration.

Furthermore, since the reflector is provided at a position corresponding to the outside of the detection area, reliable obstacle detection is possible.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a vehicle obstacle detection device according to an embodiment of the present invention, FIG. 2 is a sectional view of an ultrasonic horn of the vehicle obstacle detection device, and FIG. 3 is a perspective view of the vehicle obstacle detection device. FIG. 4 is a block diagram of the vehicle obstacle detection device, and FIG. 5 shows the vehicle obstacle detection device operating normally. FIG. 6 is a timing chart for explaining the operation when the vehicle obstacle detection device becomes abnormal. A...Vehicle obstacle detection device, B...Ultrasonic horn, D...Reflector, E...Opening, 10...Level detection circuit (including abnormality warning means), 12...
Gate circuit (including abnormality warning means), 16... Indicator (including abnormality warning means).

Claims (1)

[Scope of utility model registration request] In a vehicle obstacle detection device that detects the presence or absence of an obstacle by transmitting ultrasonic waves from a microphone having an ultrasonic horn toward the front of the horn and receiving reflected waves from an obstacle in front, A reflector is installed close to and facing one leak hole formed on the side wall of the sonic horn, and the presence or absence of reflected waves from this reflector is detected.If there is no reflected wave, an abnormality is warned. A vehicle obstacle detection device characterized by having a warning means.