JPH06331743A - Ultrasonic sensor for vehicle - Google Patents

Abstract

PURPOSE:To limit the undetectible region. CONSTITUTION:An ultrasonic oscillator 1 is provided with a rain drop detecting section 23. Upon detection of a rain drop, a gate circuit 12 shortens the period of detection gate so that the region close to the ultrasonic oscillator 1 becomes an undetectible region. Consequently, the period of detection gate is not affected by the reverberation of the ultrasonic oscillator 1 even if the duration of reverberation is extended due to adhesion of rain drop. This constitution widens the undetectible region during rain fall but does not widen the undetectible region during other time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle ultrasonic sensor for detecting an obstacle.

[0002]

2. Description of the Related Art As an ultrasonic sensor, an ultrasonic oscillator is driven to intermittently transmit ultrasonic pulses, and the ultrasonic wave reflected by an object is received by the ultrasonic oscillator. There is a so-called reflection type that detects the presence of. In this ultrasonic sensor, a specific period after the transmission of ultrasonic waves (hereinafter referred to as a detection gate period) is set, and when a reflected wave is received during this detection gate period, it is determined that an object exists. There is. In other words, by setting this detection gate period, malfunctions due to reverberant vibration of the ultrasonic transducer are prevented,
Moreover, it is possible to prevent unnecessary detection of a distant object.

An ultrasonic sensor of this type is mounted on a vehicle and is used for the purpose of assisting driving by issuing a warning to the driver when an obstacle exists so that the driver can recognize the existence of the obstacle. Has been.

[0004]

By the way, in the conventional ultrasonic sensor for a vehicle of this kind, since the sensor portion is attached to the outside of the vehicle, raindrops adhere to the sensor portion. When raindrops adhere to the sensor unit in this way, the reverberation of the ultrasonic transducer continues for a long time, and reverberation vibration may continue until the detection gate period in which a region for detecting an obstacle is set. Therefore, in the related art, by delaying the time when the detection gate is opened (the rising time when the gate signal that sets the detection gate period becomes high level), it is possible to prevent a malfunction from occurring during rainfall.

However, if the opening point of the detection gate is delayed in this way, the reflected wave from an obstacle existing at a short distance cannot be detected as an obstacle. That is, there is a problem that the non-detection area in front of the sensor unit becomes large. The present invention has been made in view of the above points, and an object of the present invention is to provide an ultrasonic sensor for a vehicle capable of minimizing a non-detection region.

[0006]

In order to achieve the above object, the invention of claim 1 is provided with raindrop detecting means for detecting the adhesion of raindrops to the ultrasonic transducer, and the raindrop detecting means detects raindrops. At this time, the gate circuit narrows the detection gate period so that the region near the ultrasonic transducer becomes the non-detection region.

In order to achieve the above object, the invention of claim 2 provides a raindrop detecting means for detecting adhesion of raindrops to an ultrasonic transducer, and when raindrops are detected by the raindrop detecting means, vibrations are applied to the raindrops. In addition, a raindrop removing means for shaking off is provided.
In order to further secure safety by giving an alarm to a person as an obstacle or a vehicle (a person riding on the vehicle), the invention of claim 3 gives an alarm to the outside of the vehicle when an obstacle is detected. Equipped with an alarm device.

[0008]

The invention of claim 1 is configured as described above, and the detection gate period is narrowed only when it rains when raindrops adhere to the ultrasonic transducer so that the area in the vicinity of the ultrasonic transducer becomes a non-detection area. By doing so, even if the reverberation vibration time of the ultrasonic transducer is prolonged due to the attachment of raindrops, the influence of the reverberation vibration of the ultrasonic transducer during the detection gate period is prevented. In short,
The non-detection hunting period is wide during rainfall, but the non-detection area should not be wide except during rainfall.

According to the second aspect of the present invention, with the above-described configuration, the state where raindrops adhere to the ultrasonic transducer is removed, and the phenomenon itself in which the reverberant vibration of the ultrasonic transducer is lengthened is eliminated. As a result, regardless of whether it is raining or not,
It prevents the non-detection area from becoming wide. According to the third aspect of the present invention, when an obstacle is detected, an alarm device for issuing an alarm to the outside of the vehicle is provided to give an alarm to a person as an obstacle or a vehicle (a person riding the vehicle). Further secure safety.

[0010]

【Example】

(Embodiment 1) An embodiment of the present invention will be described with reference to FIGS. The ultrasonic sensor of the present embodiment also drives the ultrasonic transducer to intermittently transmit ultrasonic pulses, and the ultrasonic transducer reflects the reflected wave from the object, and the ultrasonic wave is detected in the detection area. This is a so-called reflection type that detects the presence of an obstacle when the received output is obtained during the detection gate period set accordingly.

First, the circuit configuration of the ultrasonic sensor of this embodiment will be described with reference to FIG. In this ultrasonic sensor, the transmission cycle for transmitting the ultrasonic pulse from the ultrasonic transducer 1 and the gate width of the detection gate period are set to the integration circuit 2, the monostable multivibrator (hereinafter abbreviated as monostable multi). 3) and the switching circuit 4. Here, the integration circuit 2 starts the integration operation at the same time when the power is turned on, and when the integration level reaches a certain potential, the monostable multi 3
Trigger. Then, when the monostable multi 3 is triggered, the switching circuit 4 discharges the charge stored in the capacitor forming the integrating circuit 2, and causes the integrating circuit 2 to restart the integrating operation. That is, the cycle in which the monostable multi 3 is triggered by the output of the integration circuit 2 becomes the ultrasonic wave transmission cycle. Further, the gate width of the detection gate period is a fixed period until the monostable multi 3 is triggered and returns to the stable state.

The pulse width of the ultrasonic pulse transmitted from the ultrasonic transducer 1 is determined by the monostable multi 5. The monostable multi 5 is triggered by the output when the monostable multi 3 is triggered, and after the monostable multi 5 is triggered, the ultrasonic vibrator 1 is operated for a certain period until the output returns to the stable state. It becomes the pulse width of the ultrasonic pulse transmitted from.

It is the oscillation circuit 6 and the driver 7 that drive the ultrasonic transducer 1 in accordance with the output from the monostable multi 5 to transmit ultrasonic waves. It oscillates during the period when an output is given until it is triggered and returns to a stable state.
Signal for driving. Then, the driver 7 converts the high-frequency signal into a signal of a level required to drive the ultrasonic vibrator 1, and causes the ultrasonic vibrator 1 to transmit an ultrasonic wave.

The received signal of the ultrasonic transducer 1 is amplified and detected by the amplification circuit 8 and the detection circuit 9. That is, the amplifier circuit 8
Then, the so-called envelope detection is performed in which the weak received output of the ultrasonic transducer 1 is amplified, the detection circuit 9 removes the high frequency component contained in the amplified output, and only the envelope of the amplified output is extracted. Based on the amplified detection output, the level detection circuit 10, the integration circuit 11, and the gate circuit 12 determine whether the received signal is a reflected wave from an object existing in the detection area.

The level detection circuit 10 compares the detected output with a fixed level and determines whether the detected output is equal to or higher than the fixed level. The level detection circuit 10 converts the detection output into a so-called rectangular wave that has a high level when the detection output is higher than a certain level and a low level when the detection output is lower than a certain level, and thus a fine noise component with a low level. Etc. are removed by the level detection circuit 10.

The output whose level has been determined is the integration circuit 1
At 1, it is determined whether the temporal width (this width may be considered as a pulse width because it has been converted into a rectangular wave by the level detection circuit 10) is a predetermined width or more. In other words, if this time width is narrow, remove it as noise,
The output of the integrating circuit 11 reaches a predetermined level when the time width is equal to or larger than a certain width.

The integrating operation of the integrating circuit 11 is performed only during the output period of the gate circuit 12. The gate circuit 12 delays the monostable multi 3 for a fixed time and outputs it to set a detection gate period corresponding to the detection region. The integrating circuit 11 is allowed to perform the integrating operation only during the detection gate period set by the gate circuit 12. As a result, all the received signals outside the detection gate period are removed by the integration circuit 11 as being not reflected waves by an object existing in the detection region.

A switching circuit 13 is provided at the output of the integration circuit 11, and the buzzer Bz is driven each time the output of the integration circuit 11 is obtained, thereby issuing an alarm to the driver. The configuration described above is also a configuration including a conventional ultrasonic sensor of this type. The operation relating to the circuit section will be briefly described. The ultrasonic transducer 1 is driven by the output of the driver 7 shown in FIG. 2A to transmit an ultrasonic pulse. Then, when an object, that is, an obstacle is present in the detection area, the ultrasonic transducer 1 receives a reflected wave due to the obstacle as shown by (b) in FIG. The output a in the figure is due to the direct vibration of the ultrasonic vibrator 1. The output obtained by amplifying the received output of the ultrasonic transducer 1 by the amplifier circuit 8 is detected by the detection circuit 9 as shown in FIG.
The detected output is the reference level (see FIG. 2) in the level detection circuit 10.
When compared with L ₁ ) shown in (c), the level detection output shown in FIG. 2D is obtained when the reference level is L ₁ or higher.
A pulse width of the output is determined by the integration circuit 11, and it is determined whether or not the output exists within the detection gate period set by the gate circuit 12 shown in FIG. 2E. If both are satisfied, the integration circuit 11 The detection output is obtained from. When this detection output is obtained, the buzzer Bz by the switching circuit 15 is driven. Here, the switching circuit 15
Once the detection output is obtained from the integrating circuit 11, it has a function of holding the state for a certain period.

As shown in FIG. 3 (a), the sensor section S mainly composed of the ultrasonic transducer 1 is mounted on the bumper B, and the buzzer Bz is arranged inside the vehicle, and the sensor section S and the buzzer Bz are arranged. 1 except the above, that is, the circuit block C is housed inside the body A. The sensor unit S is shown in FIG.
As shown in, the housing 20 is composed of the base 20a and the cover 20b, and the ultrasonic transducer 1 is fitted into the protective rubber 21 and is mounted in the mounting recess of the base 20a. The wiring 30a that connects the sensor block S and the buzzer Bz to the circuit block C is connected using a harness connector. The mounting of the sensor portion S on the bumper B is performed by a mounting piece 20a integrally provided on the housing 20 as shown in FIG. 3B.

The portion of the protective rubber 21 located on the front surface side of the ultrasonic vibrator 1 has a horn structure whose diameter increases toward the front, and functions so that the ultrasonic vibrator 1 has a certain directivity. ing. With such a structure of the protective rubber 21, raindrops are likely to adhere to the gap (the portion indicated by a in FIG. 2) between the ultrasonic vibrator 1 and the protective rubber 21. Focusing on this point, in the present embodiment, since raindrops adhere to the gap between the ultrasonic transducer 1 and the protective rubber 21 (the portion indicated by a in FIG. 2), it is possible to detect whether or not it is raining. There is. For this purpose, as shown in FIG. 5, a flexible printed board 22 is attached to the inside of the horn portion of the protective rubber 21, and two linear copper foil patterns are attached to a portion of the flexible printed board 22 corresponding to the gap a. A pair of electrodes 23a is formed along the circumferential direction. Now, if raindrops adhere to the gap a due to rainfall, the attached raindrops (indicated by C in the figure) short-circuit the electrodes 23a,
Rain can be detected from this short-circuited state.

The output of the raindrop detector 23, which comprises the pair of electrodes 23a, is input to the gate circuit 12, as shown in FIG. The drive signal given to the ultrasonic transducer 1 when no raindrop is detected by the raindrop detector 23 is shown in FIG.
The output of the amplifier circuit 8 is shown in (a) of (a) and (b) of the same figure.
The gate signal output from the gate circuit 12 is shown in FIG. Here, the reverberant vibration of the ultrasonic transducer 1 means the vibration after the drive signal is removed in (b) of FIG.

Now, when raindrops are detected, reverberation vibration continues for a long time as shown in FIG. Therefore,
In response to the output of the raindrop detector 23, the gate circuit 12 delays the rising edge of the gate signal as shown in FIG. Even if the reverberation signal is present, if the level is equal to or lower than the detection level L ₁ of the level detection circuit 10 shown in (a) of FIG. 6B, the reverberation does not cause a malfunction. Therefore, the gate signal is made to rise after the rise time of the gate signal is reached after the level of the reverberation vibration falls below the detection level of the level detection circuit 10. In this way, the detection gate period is adjusted only during rainfall, so that there is no problem that the non-detection area near the sensor unit S is widened except during rainfall.

By the way, since the conventional ultrasonic sensor for a vehicle for detecting an obstacle gives an alarm to the driver, it does not affect a person or a vehicle (a person who gets on the vehicle) as an obstacle. There is no warning function. For example, when the ultrasonic sensor is used to detect an obstacle existing behind the vehicle, the driver can know the presence of the obstacle behind. However, from the perspective of the vehicle, it was dangerous for a person or a vehicle (a person in the vehicle) who is an obstacle because the vehicle equipped with the ultrasonic sensor does not come back.

This embodiment is intended to improve this point, and in this embodiment, the upper portion of the sensor section S is shown in FIG.
As shown in (b), an alarm unit 26 including a display device that issues a warning to a person who is an obstacle or a person who gets into a vehicle is provided. As shown in FIG. 7, the alarm unit 26 may be controlled to light by using the output of the switching circuit 13.
In this case, a timer 14 is provided between the integrating circuit 11 and the switching circuit 13. This timer 14
Is a so-called off-delay operation for holding the output state of the integrating circuit 13 for a certain period of time after the obstacle is no longer detected.

Although the alarm unit 26 is integrated with the sensor unit S in the above case, it may be a separate unit as shown in FIGS. 8 and 9. A circuit diagram in that case is shown in FIG. Further, although the case where the vehicle interior alarm is issued by the buzzer Bz in the above-described case has been described, the buzzer Bz is not necessarily required and the buzzer Bz and the display unit, or the sound generator may be used. Similarly, the alarm unit 26 may also be a buzzer, a voice generator, or a combination thereof with a display. Further, it goes without saying that the part where the alarm part 26 is provided separately may be installed in any part of the vehicle as long as it is easy for a person as an obstacle to understand.

(Embodiment 2) In the case of the above-mentioned Embodiment 1, when raindrops adhere to the gap a, it is dealt with by the processing on the circuit block side, but in this embodiment, the adhered raindrops should be removed. It was done. In this embodiment, as shown in FIG. 11, the flexible printed board 22 and the protective rubber 2
The vibrating film 24 is interposed between the vibrating film 24 and the vibrating film 24, and the vibrating film generating circuit 25 vibrates the vibrating film 24 when a raindrop is detected by the raindrop detecting unit 23 described in the first embodiment as shown in FIG. Are provided in the circuit block C. That is, when raindrops due to rainfall adhere to the gap a, the raindrop detector 23 detects the raindrop, and the vibration signal generation circuit 25 vibrates the vibrating film 24 to shake the raindrop from the gap a.
In this way, the obstacle can be detected on the circuit block C side within a certain detection gate period regardless of whether it is raining or not.

Moreover, the rain also affects the directivity of the sensor section S, and the ultrasonic waves bounced off the road surface are received, causing a malfunction. Therefore, conventionally, the mounting position of the sensor unit S is set high so that the ultrasonic waves bounced off the road surface are not received within the detection gate period. In this case, it is necessary to mount the sensor unit S at a position higher than the maximum detection distance corresponding to the falling time point of the gate signal, and therefore a large non-detection area (this non-detection area is a so-called blind spot) below the vehicle. There is a problem that occurs.

However, if the raindrops adhering to the ultrasonic transducer 1 are removed as in the present embodiment, the ultrasonic waves bounced off the road surface are received, causing no malfunction and causing a large amount of noise below the vehicle. There is no problem that an undetected area occurs. The vibration frequency of the vibrating film 24 is
Since the frequency of the ultrasonic wave transmitted from the ultrasonic vibrator 1 is sufficiently low, the influence of vibration does not reach the ultrasonic vibrator 1. However, it is preferable to devise so that vibration is not applied to the ultrasonic transducer 1 as much as possible.

[0029]

As described above, the invention of claim 1 is provided with a raindrop detecting section for detecting the attachment of raindrops to the ultrasonic vibrator, and when the raindrop is detected by the raindrop detecting means, the gate circuit uses ultrasonic waves. Since the detection gate period is narrowed so that the region near the oscillator becomes the non-detection region, even if the reverberation vibration time of the ultrasonic oscillator becomes long due to the deposition of raindrops, the ultrasonic vibration will occur during the detection gate period. It is possible to prevent the influence of the reverberation vibration of the child. For this reason, the non-detection region is widened during rain, but it is possible to prevent the non-detection region from being widened except during rain.

According to the invention of claim 2, raindrop detecting means for detecting the adhesion of raindrops to the ultrasonic vibrator, and raindrop removing means for shaking off the raindrops when the raindrop detecting means detects the raindrops. Since it is equipped with, it is possible to remove the state where raindrops are attached to the ultrasonic transducer and to eliminate the phenomenon itself that the reverberation vibration of the ultrasonic transducer becomes long. Regardless of this, it is possible to prevent the non-detection region from widening.

According to the third aspect of the present invention, since an alarm device is provided for issuing an alarm to the outside of the vehicle when an obstacle is detected, a person as an obstacle or a vehicle (a person riding on the vehicle) can be provided. An alarm can be given and safety can be improved.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a basic operation of the above.

3 (a) and 3 (b) are explanatory views showing a state in which the same is mounted on a vehicle and an attached state of a sensor unit.

FIG. 4 is a cross-sectional view of a main part of a sensor unit.

FIG. 5 is a partially cutaway perspective view showing the structure of a further main part of the sensor unit.

FIG. 6 is an explanatory diagram of a main part operation of the above.

FIG. 7 is a circuit diagram when a sensor unit equipped with an alarm unit is provided.

FIG. 8 is an explanatory diagram showing a method of arranging an alarm unit that is separate from the sensor unit.

FIG. 9 is an explanatory view showing an enlarged arrangement portion of an alarm portion.

FIG. 10 is a circuit diagram when the alarm unit is separate from the sensor unit.

FIG. 11 is a cross-sectional view of a main part of a sensor unit according to another embodiment.

FIG. 12 is a circuit diagram of the same as above.

[Explanation of symbols]

 1 Ultrasonic Transducer 12 Gate Circuit 23 Rain Drop Detection Section 24 Vibration Film 26 Alarm Section

Claims (3)

[Claims] 1. An ultrasonic oscillator is driven to intermittently transmit an ultrasonic pulse, and a reflected wave of an ultrasonic object reflected by the ultrasonic oscillator is received by the ultrasonic oscillator, and a gate circuit is provided according to a detection region. In the ultrasonic sensor for a vehicle that detects the presence of an obstacle when a received output is obtained in the detection gate period set in, a raindrop detection unit that detects the adhesion of raindrops to the ultrasonic transducer is provided, An ultrasonic sensor for a vehicle, characterized in that when a raindrop is detected by the raindrop detecting means, the gate circuit narrows the detection gate period so that the region in the vicinity of the ultrasonic transducer becomes a non-detection region. 2. An ultrasonic oscillator is driven to intermittently transmit an ultrasonic pulse, and a reflected wave of the ultrasonic wave reflected by an object is received by the ultrasonic oscillator, and a gate circuit is provided according to a detection region. In the ultrasonic sensor for a vehicle that detects the presence of an obstacle when the received output is obtained during the detection gate period set in step 1, raindrop detection means for detecting the adhesion of raindrops to the ultrasonic transducer, and raindrop detection means. An ultrasonic sensor for a vehicle, comprising: a raindrop removing means for vibrating the raindrop to shake it off when the raindrop is detected by the detecting means. 3. An ultrasonic transducer is driven to transmit ultrasonic pulses intermittently, and a reflected wave of the ultrasonic wave reflected by an object is received by the ultrasonic transducer, and is set according to a detection area. In the ultrasonic sensor for a vehicle that detects the presence of an obstacle when a received output is obtained during the detection gate period, an alarm device that issues an alarm outside the vehicle when an obstacle is detected is provided. An ultrasonic sensor for a vehicle characterized by the above.