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DESCRIPTION JPH04315400

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DESCRIPTION JPH04315400
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
ultrasonic detector for transmitting ultrasonic pulses and receiving echoes obtained by reflecting
the pulses on an object to determine the presence or absence of the object.
[0002]
2. Description of the Related Art For example, when it is necessary to arrange a plurality of
devices for detecting a vehicle using reflection echoes of ultrasonic waves, as in the case of
vehicle detection in a parking lot, devices other than one's own device The reflection echo sent
from may be received by its own device and cause a malfunction. In order to prevent such mutual
interference, conventionally, in the case of arranging a plurality of devices, it has been necessary
to perform synchronous wiring for matching the transmission timing of the ultrasonic pulse.
Recently, the need for labor-saving wiring, simple installation products, etc. has come to be
required, and asynchronous ultrasonic detectors have come out, but as shown in Fig. 5- (A), the
intervals between ultrasonic pulses are uneven. The method of sending out by is adopted. That is,
F0 is an ultrasonic frequency (for example, 40 KHz), and f1.f2.f3.f4 and f5.f6.f7.f8 (generally, this
interval is several tens of msec to several hundreds of msec, and sometimes several seconds is
there. ) Indicates an uneven time, and this uneven time is created by a microcomputer or the like.
In Fig. 5- (a), even if detectors A and B start to transmit at the same time at the same time, they
will transmit even if a certain amount of time has elapsed to transmit at non-uniform intervals. It
shows that the wave timings are mutually offset.
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[0003]
[0003] Moreover, many of the devices that perform this type of asynchronous ultrasonic wave
detection output detection output only when echoes reflected by an object are continuously
received. FIG. 6 illustrates the significance of continuous detection, but is an enlarged view of
FIG. In this figure, for example, when an ultrasonic transducer is driven by ultrasonic frequency
F0 for about 1 msec to transmit waves, and when an ultrasonic transducer used for both
transmission and reception is used, it is assumed that peculiar reverberation occurs for about 3
msec. Then, after the gate period is transmitted, a time (for example, 6 msec) is immediately set,
and the gate period is closed (for example, 10 msec) according to the distance to be detected. If a
reflection echo reflected back by the object during this gate period is received, and the reception
echo can be similarly detected within the gate period for the second transmission pulse, then, for
the transmission pulse twice in a row, The presence of an object is determined on the assumption
that a wave is received. The number of consecutive times may be two or more, however, if the
number of times is increased, the response becomes worse, but there is an advantage that the
reliability is high and malfunction does not easily occur.
[0004]
In FIG. 5 (b), although the transmission interval is equal and the detectors A and B both have f1,
the ultrasonic pulse itself changes its frequency. For example, the ultrasonic frequency F0 is 40
KHz. When the ultrasonic frequency F1 is set to 30 KHz and a plurality of devices are installed
while maintaining the difference between them without sensitivity, the detectors A and B can be
detected even if the detectors A and B are arranged adjacent to each other The synchronization
should be made in consideration of not arranging adjacent ones of the same ultrasonic pulse as
in the devices B and B. Furthermore, in Fig. 5- (f), although the ultrasonic pulse frequency is F0
and the detectors A and B are common, the respective transmission intervals are f1 for the
detector A and f2 for the detector B and fixed. By setting f1 and f2 to different frequencies, the
chances of mutual interference are reduced. Also in this case, even if detectors A and B are
arranged adjacent to each other, they are desynchronized in consideration that detectors A and
A, detectors B and B do not arrange adjacent ultrasonic pulses. I am trying to
[0005]
SUMMARY OF THE INVENTION The conventional means for desynchronizing as described above
requires expensive microcomputer means in FIG. 5- (b), and in FIG. 5- (ha) at the time of
construction. In addition to the consideration of the arrangement of the devices A and B, it is
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needless to say that the management of the product as the device of the ultrasonic detection
device requires troublesome steps.
[0006]
In view of the problems as described above, the present invention, as means for achieving
desynchronization, includes uneven transmission such as a microcomputer or the like, an array
of devices having different ultrasonic pulse frequencies, and transmission intervals. It is an object
of the present invention to provide an economical ultrasonic detection device which does not
particularly consider the arrangement of devices without depending on the means of
arrangement of different devices.
[0007]
SUMMARY OF THE INVENTION In order to achieve the above object, in the ultrasonic detecting
apparatus according to the present invention, the interval for transmitting ultrasonic waves is
changed according to the pulse width of the detected reflected echo, or Depending on the voltage
level of the receiving waveform when the device receives the reflection echo, or when the device
receives a large number of pulses due to the reflection echo by multiple reflections, the number
of receiving waveforms above a predetermined voltage level Also, if the ultrasonic transducer
that transmits and receives ultrasonic waves is used for both transmission and reception,
depending on the reverberation value after transmitting the ultrasonic waves, and by multiple
reflections, multiple pulses due to reflection echo are received by the device. Interval of
transmitting ultrasonic pulse by combining the pulse width and voltage level of the reflection
echo, the number of received waveforms above the predetermined voltage level, and the width of
the reverberation level. Change and control to performs a desynchronized operation.
[0008]
In the ultrasonic detecting apparatus according to the present invention having the abovedescribed means, only the pulse width of the first receiving waveform when the reflection echo
receives a large number of pulses by the multiple reflection by the multiple reflection. Also,
depending on the voltage level of the receiving waveform when the reflection echo is received by
the device, or the sum of all pulse widths when the reflection echo receives multiple pulses to the
device by multiple reflection, or any combination. The reflected echo is also received by the
waveform receiving the most time difference from the transmission timing when the reflected
echo receives multiple-sum pulses due to multiple pulse reflections, and the reflected echo is also
received. The amplifying means to be amplified is separated into a first amplifying means and a
second amplifying means, the first amplifying means is a gain which is not amplified until the
receiving waveform becomes a rectangular wave, and the reflection echo is reflected by multiple
reflections. Vessels is when receiving a large number of pulses, the value obtained by summing
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the voltage level of the predetermined voltage level or received wave waveform, controls the
interval for sending the ultrasonic pulse.
[0009]
Embodiments of the ultrasonic detecting apparatus according to the present invention will be
described below with reference to the drawings.
FIG. 1- (a) shows a circuit block diagram of the first embodiment.
An ultrasonic pulse (for example, 40 KHz) is intermittently emitted by the ultrasonic transducer 2
at, for example, a 100 msec cycle by the transmission signal generation circuit 1, and a reflection
echo from an object is received by the amplification detection circuit 3 and the waveform
shaping circuit 4. When a wave receiving signal is input within a period of a gate signal which is
replaced with a wave signal and which is input to the gate circuit 6 from the transmission signal
generation circuit 1 through the gate signal circuit 5 in the gate circuit 6, the gate circuit 6 is
Outputs an output to the output drive circuit 7, which drives the display 8.
Here, the waveform before the detection of the amplification detection circuit 3 is as shown in
FIG. 1- (b), and the pulse width at a predetermined voltage of the reception echo on the time
chart is read by the width detection circuit 9. .
The width of this received echo causes non-uniform variation depending on conditions such as
the shape, angle, size, surface condition, temperature, presence of wind, etc. of the object. By
feeding back as a constant coefficient that determines the cycle of 1, 100 msec is changed in a
width of, for example, about 60 msec to 200 msec at the time of activation. The detection output
is displayed on the display 8 only when echoes reflected by the object can be continuously
received.
[0010]
In the case where the ultrasonic detecting apparatus according to the present invention is
attached to a ceiling and sound waves are transmitted toward the floor surface, an ultrasonic
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pulse which is usually transmitted for the first time as shown in FIG. 1- (c). Reflect multiple times
while attenuating the ceiling and floor. Usually, the first received echo is amplified up to the
power supply voltage by the amplifier circuit that amplifies the received wave, in other words, to
a rectangular wave, so the difference in detectors with similar working conditions at the voltage
level Does not come out. Therefore, the pulse width of the waveform reaching the predetermined
voltage level of the first reception echo is used as a coefficient for changing the transmission
interval. The output of the gate signal generation circuit 5 is input to the width detection circuit
9, and only the width of the first reception echo of the reception signal of the amplification
detection circuit 3 is extracted and input to the transmission signal generation circuit 1. Also, in
order to ensure effective variation as the coefficient of the variable range of the transmission
interval, if it is assumed that the first to fourth echoes are generated as in the case of the
reception echo of FIG. The multiple reflection echoes are taken out and the transmission interval
is changed and controlled by the sum.
[0011]
By the way, FIG. 2- (A) shows a circuit block diagram of the second embodiment of the ultrasonic
wave detecting apparatus according to the present invention, but the waveform of the
transmitted / received wave before the detection of the amplification detection circuit 3 is shown.
Is as shown in FIG. 2 (b), and the voltage detection circuit 10 reads the voltage value of the
reception echo on the time chart. The voltage level of this reception echo causes non-uniform
variation depending on the shape, angle, size, surface condition, temperature, presence of wind,
etc. of the object. By feeding back as a constant factor that determines the cycle of 1, the 100
msec cycle is changed, for example, in a width of about 60 msec to 200 msec at the time of
startup. Assuming that four echoes are generated due to multiple reflections as shown in FIG. 2
(ha), the voltage level V1 of the fourth echo which does not become rectangular is input to the
voltage detection circuit 10 and the gate signal is generated. The transmission interval of the
transmission signal generation circuit 1 is used as a coefficient to determine the input by the
circuit 5.
[0012]
In an ordinary amplification circuit, the first received echo is completely rectangular as shown by
the output b in FIG. 3 (b), and the voltage is obtained in the first received echo that is most easily
processed in the circuit. Level differences can not be extracted with other detectors. Therefore, as
shown in the circuit block diagram of the third embodiment of the ultrasonic detecting apparatus
according to the present invention shown in FIG. 3- (A), the first amplifying circuit 11 and the
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second amplifying circuit 12 are separated and The amplification gain of the amplification
detection circuit 3 of the circuit block diagram of the second embodiment shown in (a) is
distributed, and the output of the first amplification circuit 11 is always the output of the first
received echo of the output a in FIG. So as not to saturate. As means for this purpose, a gain is
provided to the first amplifier circuit 11 so that the voltage does not saturate even if the target
object is within the target distance, or the gain of the first amplifier circuit 11 can always be
varied by auto gain control. As a first received echo of the output a. Then, as in the case of the
reception echo shown in FIG. 2-(c), assuming that the first reception echo to the fourth reception
echo are generated, arbitrary multiple reflection echoes are taken out, and the transmission
interval is calculated by the sum. Change and control. Also, when the ultrasonic transducer 2 is
used as a transmission / reception wave, a unique reverberation occurs after transmission as
shown in FIG. 4, but the ultrasonic transducer 2 detects the time interval of reverberation at a
predetermined voltage that is dispersed Then, control is performed by changing the transmission
interval.
[0013]
Effect of the Invention The ultrasonic detecting device according to the present invention has the
above-described configuration, and therefore has the following effects. That is, there is no need
for a means to perform expensive control operation by nonuniform transmission by a
microcomputer or the like, and to desynchronize equipment with different ultrasonic frequency
and transmission synchronization by arrangement, for example, wave width, voltage, echo
number・ Asynchronous operation such as reverberant value, etc. is performed by various
amounts with variations peculiar to ultrasonic waves, and by combination thereof, it is not
necessary to pay particular attention to the arrangement even if a plurality of devices are
installed, which is economical It has an excellent effect of being able to perform typical
equipment placement work.
[0014]
Brief description of the drawings
[0015]
Fig. 1 (a) is a circuit block diagram showing a first embodiment of the ultrasonic detection device
according to the present invention, (b) is a waveform diagram of transmission / reception before
detection by the amplification detection circuit same as the above. C) A waveform chart from the
first received echo to the fourth received echo as in the above received echo.
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[0016]
Fig. 2 (a) is a circuit block diagram showing a second embodiment of the ultrasonic detection
device according to the present invention, (b) is a waveform diagram of transmission / reception
before detection by the amplification detection circuit of the same embodiment, Ha) is a
waveform diagram of the received wave when multiple echoes of the same generation are
generated.
[0017]
FIG. 3 (a) is a circuit block diagram showing a third embodiment of the ultrasonic wave detection
device according to the present invention, and FIG. 3 (b) is a wave transmission before detection
by the first amplification detection circuit and the second amplification detection circuit.・
Waveform of received wave.
[0018]
Fig. 4 A waveform chart of the unique reverberation that occurs when using an ultrasonic
transducer as both transmission and reception.
[0019]
Fig. 5 (a) is a waveform diagram showing that the transmission timings are shifted from each
other even if the two detectors start transmission simultaneously at the same time in the
conventional non-synchronous ultrasonic detection device. (B) is a waveform diagram showing
that the transmission interval of the two detectors above is equal, but the ultrasonic pulse itself
changes the frequency, (c) is the ultrasound of the two above detectors. The wave form diagram
when pulse frequency is common, but each transmission interval is made into a different
frequency.
[0020]
Fig. 6 A waveform chart for explaining the significance of continuous detection of ultrasonic
waves.
[0021]
Explanation of sign
[0022]
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DESCRIPTION OF SYMBOLS 1 Transmitting signal generation circuit 2 Ultrasonic vibrator 3
Amplification detection circuit 4 Waveform shaping circuit 5 Gate signal generation circuit 6
Gate circuit 7 Output drive circuit 8 Display 9 Width detection circuit
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