JP2001221858A - Ultrasonic sensor apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily discriminate a reflected wave, with respect to noise and to expand a measuring range of an approach distance. SOLUTION: A controller 10 is equipped with a microcomputer 20 to output an oscillation pulse signal 'a' to a signal line 39 via a modulation transistor 18 and inputs the reflected wave signal f' obtained by passing the receiving signal from the sensor part 40A via a detector 33 to detect an obstacle or the like. In the sensor part 40A, an ultrasonic microphone 42 is driven by an output circuit 50 to send out an ultrasonic wave and the receiving signal c' is passed via an amplifier 70, limiter 72, a band-pass filter 74, a detector 76 or the like to be sent to a FET transistor 80 to obtain a large signal b', which is, in turn outputted to the signal line. Even if noise is mixed from the signal line by the large signal, the discrimination of a reflected wave is easy, and since the input level of the detector is suppressed by the amplifier and the limiter, the reverbration component of the ultrasonic microphone is shortened and a detectable distance becomes shorter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic sensor device mounted on a vehicle and used for detecting obstacles around the vehicle.

[0002]

2. Description of the Related Art An ultrasonic sensor device transmits an ultrasonic wave from a transmitter, receives a reflected wave from an object within a detection range by a receiver, and detects a reflected wave, that is, a reflected wave from the transmission. The distance to the object is detected based on the time difference until reception. Using this for a vehicle, as an alarm is issued when the detected obstacle is within a predetermined distance,
There is such as shown in FIG. This comprises a sensor unit for transmitting and receiving ultrasonic waves and a controller connected to the sensor unit. The controller controls the sensor unit and drives a buzzer based on the detected reflected wave to issue an alarm. FIG. 6 shows a signal waveform in each section.

[0003] The controller 10 has a power supply terminal 11 connected to the battery 1 via the ignition switch 2;
An output terminal 13 connected to the buzzer 3 and a first control communication terminal 12 connected to the sensor unit 40 are provided, and a microcomputer 20 is provided inside. Microcomputer 2
0 is operated by the constant voltage source 14 connected to the power supply terminal 11 and outputting 5V. From the oscillation output terminal 22, 40
While outputting the KHz oscillation pulse signal a, the reflected wave signal f is input to the input terminal 21 to calculate the distance to the reflecting object based on the time difference, and the buzzer drive signal is output from the drive output terminal 23 according to the distance. Output.

A modulation transistor 18 is provided between the power supply terminal 11 and the control terminal 12.
The collector of 8 is connected to the power supply terminal 11, and the emitter is connected to the first control communication terminal 12 via the resistor 19. The base connected to the collector via the resistor 30 is
It is connected to the collector of the control transistor 16 via a zener diode 17. The base of the control transistor 16 is connected to the oscillation output terminal 22 of the microcomputer 20 via the resistor 15, and the emitter is grounded.

The signal line 39 also serves as a power supply line from the controller 10 to the sensor section 40. The voltage on the signal line 39 passing from the 12V battery to the modulation transistor 18 and the resistor is 7 to 8V. The modulation transistor 18 is normally set to ON, and the voltage input to the power supply terminal 11 is applied to the microcomputer 20 via the control transistor 16.
The signal b0 modulated by the oscillation pulse signal from the first control communication terminal 12 is supplied to the first control communication terminal 12.

An amplifier (AMP) 32, a detector 33 and a comparator 34 are sequentially connected to the first control communication terminal 12 via a capacitor 31.
4 is the input terminal 21 of the microcomputer 20
It is connected to the. A drive transistor 3 is connected to a drive output terminal 23 of the microcomputer 20 via a resistor 35.
6, the base of the driving transistor 36 is connected to the output terminal 13, and the emitter is grounded. The buzzer 3 is connected between the power terminal 11 and the output terminal 13.

[0007] The sensor unit 40 is a first
The control communication terminal 12 includes a second control communication terminal 41 connected to the control communication terminal 12 via a signal line 39, and an ultrasonic microphone 42 including a piezoelectric element. The ultrasonic microphone 42 also serves as an ultrasonic transmitter and a reflected wave receiver. The ultrasonic microphone 42 is connected between the second control communication terminal 41 and the ultrasonic microphone 42 based on a signal received from the controller 10 to the second control communication terminal 41.
An output circuit 50 for generating a drive pulse to the drive circuit is provided. Between the ultrasonic microphone 42 and the second control communication terminal 41, an amplifier 60 (AMP) for a reflected wave received by the ultrasonic microphone 42 and a band-pass filter 65 are further provided.

The output circuit 50 mainly includes transistors 51 and 52 and a transformer 58 connected in series, and the emitter of the transistor 51 has a capacitor 54 whose one end is grounded.
Is connected to the second control communication terminal 41 via a diode 53. The base of the transistor 51 is connected to the second control communication terminal 41 via the resistor 55.
It is connected to the.

The base of the transistor 52 is also connected to the second control communication terminal 41 via the resistor 56, and the emitter is grounded. A connection point between the collector of the transistor 51 and the collector of the transistor 52 is connected to a primary side of a transformer 58 via a capacitor 57, and a secondary side of the transformer 58 is connected to the ultrasonic microphone 42.

An amplifier 60 receives a signal received by the ultrasonic microphone 42 via a capacitor 59, and amplifies the received signal at a constant amplification factor. The band-pass filter 65 is 40 KH
It is set so that only a signal of a predetermined width centered on z is passed. A capacitor 66 is provided between the band pass filter 65 and the second control communication terminal 41.

In the sensor section 40, an output circuit 50 outputs transistors 51 and 5 based on a signal from the controller 10.
2 alternately repeats on / off to generate a drive pulse c0, thereby driving the ultrasonic microphone 42 to transmit ultrasonic waves. When the ultrasonic microphone 42 receives a reflected wave that has returned after hitting an obstacle or the like, the reflected waves c1, c2,
After the received signal cR including c3 is amplified by the amplifier 60,
The signal is output to the signal line 39 connected to the second control communication terminal 41 via the band pass filter 65. Note that c1, c
2 and c3 are reflected wave signals from obstacles and the like at different distances.

In FIG. 6, dR (d1, d2, d3) is a received signal corresponding to the reflected wave amplified by the amplifier 60. The drive pulse c is limited by the limitation of the operating voltage of the amplifier 60.
The amplified signal d0 of 0 has a predetermined maximum amplitude. FIG.
B, excluding b0, bz, bR (b1, b2, b
3) is a signal output on the signal line 39 via the band pass filter 65. In particular, b1, b2, and b3 include those having a lower value of about 50 mV.

In the controller 10, after the received signal d on the signal line 39 is amplified by the amplifier 32, detection is performed by the detector 33. The detector 33 includes a capacitor having a large capacity corresponding to the large signal amplified by the amplifier 60 and further amplified by the amplifier 32. The comparator 34 limits the detected signal e to a signal having a predetermined strength or more, shapes the waveform, and outputs the reflected signal fR (f1, f2, f3). The microcomputer 20 uses the comparator 34
A predetermined calculation is performed on the basis of the reflected wave signal fR output from and the previously output oscillation pulse signal a to determine the distance to an obstacle or the like.

According to the ultrasonic sensor device as described above, the transmission and reception of ultrasonic waves are performed by a single ultrasonic microphone 42, so that the size and the cost are reduced and the signal line 39 is connected to the sensor. Since the power supply line also serves as the power supply line for the unit 40, there is an advantage that the configuration can be simplified.
Further, various applications have been proposed, such as not only obstacle detection but also measurement of a distance between a vehicle floor and a road surface, for example.

[0015]

However, in the above-mentioned conventional apparatus, the controller 10 and the sensor section 40 are separated from each other and are connected by a signal line 39. Through which noise is likely to be mixed. On the other hand, the reflected wave signal received by the sensor unit 40 is weaker as the distance to the obstacle is longer, and the reception voltage is sequentially reduced as indicated by c1, c2, and c3. However, there is a problem that if there is a noise of about 50 mV, particularly a reflected wave from a long distance is buried in the noise, making it difficult to identify the reflected wave.

An ultrasonic microphone 4 using a piezoelectric element or the like
No. 2 has a problem that reverberation cz is accompanied when this is driven. Even if the reverberation component dz (bz on the signal line) which is inevitably generated by using the single ultrasonic microphone 42 for transmitting the ultrasonic wave and receiving the reflected wave disappears, the detector 33
Since the large-capacity capacitor is provided, the reverberation detection state S continues until time X for a while after the disappearance. Therefore, in the measurement of a close distance such as a road surface with a short detection distance, if the reflected wave signals overlap during the reverberation detection state, there is a possibility that the identification becomes difficult. Therefore, in view of the above problems, an object of the present invention is to provide an ultrasonic sensor device capable of easily identifying a reflected wave with respect to noise and further expanding a measurement range of a close distance.

[0017]

According to the present invention, a sensor unit having a single ultrasonic transmitter / receiver for transmitting / receiving ultrasonic waves is connected to the sensor unit via a signal line. An ultrasonic sensor device comprising: a controller for detecting the presence of an object within a detection range from a detection state of a reflected wave, wherein the sensor unit comprises: an amplifier for amplifying a reception signal received by an ultrasonic transceiver; A limiter that limits the amplitude of the received signal, and a detector that performs a detection process on the amplitude-limited received signal, and outputs the detection result to a controller via a signal line. And a reflected wave extracting means for extracting a reflected wave from the object from the object. Since the received signal is amplified by the sensor unit, passed through a limiter, detected, and output to the controller, the reflected wave from a short distance and the reflected wave from a long distance can be obtained as a signal of the same level. Even if noise is mixed in from the controller, it is easy to identify the reflected wave by the controller.

According to a second aspect of the present invention, the sensor unit is configured to be supplied with power from the controller through a signal line,
A level conversion means for converting the detection result of the detector into a level one digit lower than the power supply voltage and outputting the converted signal to a signal line is provided. Since the detection signal is output to the controller as a large voltage signal, it is easier to identify noise that may be mixed in from the signal line, and the detection of an obstacle or the like is reliably performed.

According to a third aspect of the present invention, in particular, the amplifier amplifies the received signal so that a reflected wave signal from an object within a detection range becomes a predetermined level or more, and a limiter converts the received signal amplified by the amplifier to the above-mentioned signal. The amplitude is limited to an amplitude near a predetermined level. Since the input signal to the detector is at a low level, the capacitance of the capacitor forming the detector can be reduced, and as a result, the detection state of reverberation following the ultrasonic microphone drive in the detector disappears in a short time. In addition, the region where the reflected waves overlap and cannot be identified is reduced, and the reflected waves from a closer distance than before can be detected.

According to a fourth aspect of the present invention, there is provided a sensor unit which includes a single ultrasonic transmitter / receiver, is supplied with power from the controller side through the first signal line, and transmits / receives ultrasonic waves, and a detection range from a detection state of the reflected wave An ultrasonic sensor device comprising: a controller that detects the presence of an object in the ultrasonic sensor device, wherein the sensor unit includes an amplifier that amplifies a reception signal received by the ultrasonic transceiver, and a limiter that limits an amplitude of the amplified reception signal. And a reflected wave extracting means for extracting a reflected wave from the object from the amplitude-limited received signal, and outputting the extraction result to the controller via the second signal line. Since the sensor unit amplifies the received signal and passes it through the limiter, the reflected wave from a short distance and the reflected wave from a long distance are the same level of the received signal. Then, since the reflected wave is extracted by the sensor unit and output to the controller, the problem that identification is difficult due to being buried in noise is solved.

According to a fifth aspect of the present invention, there is provided a detector wherein the reflected wave extracting means of the sensor section performs a detection process on the reception signal whose amplitude is limited by the limiter, and an A / D conversion means for converting the detection result into a digital signal. Therefore, when the controller includes a microcomputer, for example, the digital signal can be directly input to the microcomputer to detect the presence of an object.

[0022]

Next, embodiments of the present invention will be described with reference to examples. FIG. 1 is a diagram showing the configuration of the embodiment. FIG. 2 shows a signal waveform in each section. In the controller 10 </ b> A, the comparator 34 is directly connected to the first control communication terminal 12, and the output side of the comparator 34 is connected to the input terminal 21 of the microcomputer 20. No amplifier and detector are provided. Controller 10
The other configuration of A is the same as that of the controller 10 in the conventional device shown in FIG. The buzzer 3 is connected to the output terminal 13 of the controller 10A as in the conventional device.

The sensor unit 40A includes a second control communication terminal 41 connected to the first control communication terminal 12 of the controller 10A by a signal line 39, and an ultrasonic microphone 42 made of a piezoelectric element.
Is provided. Between the second control communication terminal 41 and the ultrasonic microphone 42, the controller 10A sends the second control communication terminal 41
An output circuit 50 is provided for generating a drive pulse for the ultrasonic microphone 42 based on the signal received by the control unit 50. The output circuit 50 is the same as the output circuit in the conventional device shown in FIG. 5, and the secondary side of the transformer 58 is connected to the ultrasonic microphone 42.

An amplifier 70, a limiter 72, a band-pass filter 74, a detector 76, and a waveform shaping circuit 78 are sequentially connected to the ultrasonic microphone 42 via a capacitor 59. The detector 76 includes an input resistor 90 and the resistor 90.
And a capacitor 91 and a resistor 92 provided in parallel with each other between the ground and the ground.

On the other hand, series resistors 81 and 82 are connected to the second control communication terminal 41, and the connection point of the resistor 82 with the resistor 81 is grounded via the FET transistor 80.
The other end of the resistor 82 is grounded. The output of the waveform shaping circuit 78 is connected to the gate of the FET transistor 80.

In the above configuration, in the sensor section 40A,
In the output circuit 50, the transistors 51 and 52 alternately turn on and off on the basis of a signal from the controller 10A to generate a drive pulse c0, thereby driving the ultrasonic microphone 42 to transmit ultrasonic waves. When the ultrasonic microphone 42 receives the reflected wave that has returned after hitting an obstacle or the like, the reception signal cR including the reflected waves c1, c2, and c3.
After being amplified by the amplifier 70, the amplitude is limited by the limiter 72.

The amplifier 70 has an amplification factor substantially corresponding to the total amplification factor of the amplifiers 60 and 32 in the conventional device shown in FIG. Are set to be equal to or higher than a predetermined level. The limiter 72 limits the amplitude of the signal amplified by the amplifier 70 to a level near the predetermined level. Thereby, the reflected wave included in the received signal is greatly amplified and then passes through the limiter, and the reflected wave signal after passing through the limiter is shown in FIG. 2 by dR ′ (d1 ′, d1 ′).
2 ′, d3 ′), both have waveforms of the same level of amplitude.

The ultrasonic microphone 4 is controlled by a limiter.
2 and the amplitude of the subsequent reverberation signal is also d
Since the voltage is kept low near the predetermined level like 0 'and dz', the capacitance of the capacitor in the detector is set to a low capacitance corresponding to the limited amplitude. as a result,
When the reverberation component becomes equal to or less than the predetermined value, the capacitor immediately completes discharging, whereby the reverberation detection state SA indicated by the reverberation signal dz 'extracted by the detector is changed from the conventional reverberation detection state S shown in FIG. Also disappears by W in a short time.

In FIG. 2, e 'indicates the output of the FET transistor 80 driven by the signal whose waveform has been shaped by the waveform shaping circuit 78, and bz', bR '(b1', b2 ', b3').
Is a signal output from the FET transistor 80 on the signal line 39 after the voltage is adjusted by the resistors 81 and 82.
The FET transistor 80 and the resistors 81 and 82 form the level conversion means of the present invention.
R '(b1', b2 ', b3') is a pulse signal lower by 0.5 to 1.0 V than the power supply voltage on the signal line.
f 'is a reflected wave signal extracted by the comparator 34 in the controller 10A. In this embodiment, the comparator 34 constitutes a reflected wave extracting means.

The present embodiment is configured as described above. In the ultrasonic sensor device in which a sensor unit 40A for transmitting and receiving ultrasonic waves by a single ultrasonic microphone 42 and a controller 10A for controlling the same are connected by a signal line 39. , The sensor unit 40A converts the signal received by the ultrasonic microphone 42 into an amplifier 70 and a limiter 72.
, Detection is performed after passing through the controller 10A, so that both the reflected wave from a short distance and the reflected wave from a long distance are extracted with the same level of amplitude. To the signal line 3
Even if noise is mixed in from No. 9, it is easy to identify, and the detection of an obstacle or the like is reliably performed.

Since the signal amplified by the amplifier 70 is limited in amplitude by the limiter 72, when the reverberation component following the drive of the ultrasonic microphone 42 is detected, the reverberation detection state ends almost in the same manner as the reverberation disappearance. The region where the reflected wave overlaps the reverberation detection state and cannot be identified is reduced, and the reflected wave from a closer distance than before can be detected.

In the embodiment, the ultrasonic microphone 42 composed of a piezoelectric element is used as a single ultrasonic transmitter / receiver, but various alternatives can be used. In addition, the buzzer 3 is operated by the drive output of the controller 10A. However, the present invention is not limited to this, and the distance to a reflective object such as an obstacle may be visually displayed.

In addition, the controller 1 in the embodiment
At 0A, as a reflected wave extracting means, the comparator 34 extracts a signal having a predetermined intensity or higher from the signal on the signal line 39. As a modified example, as shown in FIG. The input can be directly connected to the A / D conversion terminal 24 of the microcomputer 20, and the comparator 34 can be omitted. In this case, the microcomputer 20 also functions as the reflected wave extracting means.

Further, in the embodiment, the F of the sensor section 40A is
The output of the ET transistor 80 is adjusted by resistors 81 and 82 and output on the signal line 39, and the reflected wave is extracted by the controller 10A, as shown in FIG.
In the sensor section 40C, the output of the FET transistor 80 is not put on the signal line 39 (first signal line), which is a power supply line, and is directly input to the microcomputer 20 of the controller 10C using the separate second signal line 45. You may make it connect to the terminal 21. The output of the FET transistor 80 is a digital signal. In this case, the detector 76, the waveform shaping circuit 78, and the FET transistor 80 in the sensor section constitute reflected wave extracting means, and the FET transistor 80 particularly corresponds to A / D converting means.

[0035]

As described above, according to the first aspect of the present invention, there is provided an amplifier for amplifying a reception signal received by an ultrasonic transceiver by a sensor unit, a limiter for limiting the amplitude of the amplified reception signal, and an amplitude limiter. And a detector for performing a detection process on the received signal, outputting a detection result to a controller via a signal line, and the controller having a reflected wave extraction unit for extracting a reflected wave from an object from the detection result. Therefore, the reflected wave from a short distance and the reflected wave from a long distance can be obtained as the same level signal, and even if noise is mixed in from the signal line 39, the reflected wave can be easily identified by the controller. Has the effect that

According to the second aspect of the present invention, the detection result of the detector is converted by the level conversion means to a level which is one digit lower than the power supply voltage of the sensor unit and output to the signal line. Discrimination of the resulting noise is easier.

According to a third aspect of the present invention, the reflected wave signal is amplified by an amplifier so as to be higher than a predetermined level, and the amplified received signal is limited to an amplitude near the predetermined level by a limiter. As a result, the input signal to the detector becomes low and the capacitance of the capacitor of the detector can be reduced, and the reverberation detection state ends in a short time.

According to a fourth aspect of the present invention, there is provided an amplifier for amplifying a received signal received by an ultrasonic transmitter / receiver on a sensor unit side, a limiter for limiting the amplitude of the amplified received signal, And a reflected wave extracting means for extracting the reflected wave from the device, and outputting the extraction result to the controller via the second signal line. Since the sensor unit amplifies the received signal and passes it through the limiter, the received signal of the reflected wave can be at the same level regardless of distance, and the sensor unit extracts the reflected wave and outputs it to the controller, so it is buried in noise. It does not make identification difficult.

According to a fifth aspect of the present invention, in particular, the reflected wave extracting means of the sensor unit is provided with a detector for performing a detection process on the reception signal whose amplitude is limited by the limiter, and an A / D converter for converting the detection result into a digital signal. Therefore, the digital signal is received and the processing by the controller is easy.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing signal waveforms at various parts of the embodiment device.

FIG. 3 is a diagram showing a modification.

FIG. 4 is a diagram showing another modification.

FIG. 5 is a diagram showing a conventional example.

FIG. 6 is a diagram showing signal waveforms at various parts in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery 2 Ignition switch 3 Buzzer 10 Controller 10A, 10B, 10C Controller 11 Power supply terminal 12 First control communication terminal 13 Output terminal 14 Constant voltage source 15, 19 Resistance 16 Control transistor 17 Tsuena diode 18 Modulation transistor 20 Microcomputer 21 Input Terminal 22 Oscillation output terminal 23 Drive output terminal 24 A / D conversion terminal 30 Resistance 31 Capacitor 32 Amplifier 33 Detector 34 Comparator 35 Resistance 36 Drive transistor 39, 45 Signal line 40 Sensor unit 40A, 40C Sensor unit 41 Second control communication terminal 42 Ultrasonic microphone 50 Output circuit 51, 52 Transistor 54 Capacitor 53 Diode 55, 56 Resistance 57 Capacitor 58, 59 Transformer 60 Amplifier 65 Bandpass Filter 68 capacitor 70 amplifier 72 limiter 74 band-pass filter 76 detector 78 waveform shaping circuit 80 FET transistors 81, 82 resistor 90 input resistor 91 capacitor 92 resistor

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G005 AA04 5J083 AA02 AC05 AC16 AC18 AC31 AD04 AE10 AF05 BE11 BE18 BE19 BE38 BE54 CA01 CA10 EB10 EB11

Claims (5)

[Claims] 1. A sensor unit having a single ultrasonic transmitter / receiver for transmitting and receiving ultrasonic waves, and connected to the sensor unit via a signal line to detect the presence of an object within a detection range from a detection state of a reflected wave. An ultrasonic sensor device comprising a controller for detecting, an amplifier for amplifying a received signal received by an ultrasonic transmitter / receiver, a limiter for limiting an amplitude of the amplified received signal, and an amplitude limited. A detector that performs a detection process on the received signal, and outputs a detection result to the controller via the signal line, and the controller extracts a reflection wave from the object from the detection result. An ultrasonic sensor device having extraction means. 2. The apparatus according to claim 1, wherein the sensor unit is provided with level conversion means which is supplied with power from a controller through the signal line, converts the detection result to a digit level of a power supply voltage, and outputs the digitized level to the signal line. The ultrasonic sensor device according to claim 1, wherein 3. The amplifier amplifies a received signal so that a reflected wave signal from an object within a detection range is equal to or higher than a predetermined level, and the limiter converts the received signal amplified by the amplifier into a signal near the predetermined level. The ultrasonic sensor device according to claim 1, wherein the amplitude is limited to: 4. A sensor unit having a single ultrasonic transmitting / receiving body, which is supplied with power from a controller through a first signal line and transmits / receives ultrasonic waves, and the presence of an object within a detection range from a detection state of a reflected wave. An ultrasonic sensor device comprising a controller that detects
An amplifier that amplifies a received signal received by the ultrasonic transceiver, a limiter that limits the amplitude of the amplified received signal, and a reflected wave extracting unit that extracts a reflected wave from the object from the amplitude-limited received signal. An ultrasonic sensor device that outputs the extraction result to the controller via a second signal line. 5. The apparatus according to claim 1, wherein the reflected wave extracting means includes a detector for performing a detection process on the reception signal whose amplitude is limited by the limiter, and an A / D conversion means for converting the detection result into a digital signal. The ultrasonic sensor device according to claim 4, wherein