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DESCRIPTION JPH05232241

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DESCRIPTION JPH05232241
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
ultrasonic sensor for detecting an object present in front of an ultrasonic transducer.
[0002]
2. Description of the Related Art A conventional ultrasonic sensor comprises an ultrasonic wave
transmitter for transmitting ultrasonic pulses and an ultrasonic wave receiver for receiving
ultrasonic pulses arranged in parallel in proximity to the ultrasonic wave transmitter. , A
transmission signal circuit that intermittently outputs ultrasonic pulses at a predetermined
frequency to the ultrasonic transmitter, and a reception signal that the ultrasonic wave receiver
receives between the transmission and the next transmission. It consists of a wave receiving
signal processing circuit that detects an object compared to a predetermined threshold value, and
notification means that is driven by the input of an output signal from the wave receiving signal
processing circuit and indicates the presence or absence of an object. The ultrasonic wave
transmitter has an ultrasonic transducer (not shown) using a piezoelectric element or the like and
a horn portion in front of the ultrasonic transducer, and is connected to the transmission signal
circuit, and is connected from the transmission signal circuit The ultrasonic pulse signal is
transmitted in response to the transmission signal. The ultrasonic wave receiver is made of the
same material as the ultrasonic wave transmitter, and is connected to the wave receiving signal
processing circuit to receive a drive signal, a wraparound signal, and a reflected wave from an
object. The notification means comprises a display or a speaker for display.
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[0003]
This system reports the presence of an object when the level of a reflected wave from an object
appearing between a transmission wave and the next transmission wave, ie, a wraparound signal
and the next drive signal, is equal to or higher than a predetermined threshold.
[0004]
SUMMARY OF THE INVENTION The ultrasonic sensor as described above has a horn and
ultrasonic vibration because the ultrasonic wave transmitter and the horn of the ultrasonic wave
receiver are opened outward. If foreign matter such as snow or mud adheres to the vibrating
surface of the child, or the attached water droplets freeze, the sensitivity of the ultrasonic wave
transmitter and the ultrasonic wave receiver's transmission and reception decreases. It falsely
detects that there is no obstacle even though there is an obstacle in front of the ultrasonic
transducer.
[0005]
The present invention has been made in view of such circumstances, and an object thereof is to
provide an ultrasonic sensor that detects a drop in sensitivity of transmission or reception and
notifies an abnormal operation state.
[0006]
SUMMARY OF THE INVENTION In order to achieve the above object, the ultrasonic sensor
according to the present invention comprises an ultrasonic wave transmitter for transmitting an
ultrasonic pulse and an ultrasonic wave transmitter in close proximity to the ultrasonic wave
transmitter. An ultrasonic wave receiver configured to receive ultrasonic pulses, a transmission
signal circuit intermittently outputting ultrasonic pulses at a predetermined frequency to the
ultrasonic wave transmitter, and a period between transmission and next transmission A received
signal processing circuit for detecting an object by comparing a received signal received by the
ultrasonic wave receiver with a predetermined threshold value, and an input of an output signal
from the received signal processing circuit to detect an object An ultrasonic sensor having
notification means for notifying the presence or absence of the ultrasonic wave, monitoring the
time during which a wraparound signal of a predetermined level or more is inputted from the
ultrasonic wave transmitter to the ultrasonic wave receiver in the reception signal processing
circuit; , Provided time monitoring means to notify of an abnormality when this time has changed
beyond a predetermined level We are trying to be.
[0007]
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2
According to this configuration, the time during which a wraparound signal of a predetermined
level or more is input is monitored, and an abnormality is notified when this time changes to a
predetermined level or more, whereby ultrasonic waves are received from the ultrasonic wave
transmitter. Attenuation of a wraparound signal input to the waver can be recognized, and
abnormalities around the ultrasonic wave transmitter and the ultrasonic wave receiver can be
known.
[0008]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A first embodiment of the present
invention will be described below with reference to FIGS.
[0009]
1 The ultrasonic wave transmitter includes an ultrasonic transducer 1a using a piezoelectric
element or the like and a horn unit 1b in front of the ultrasonic transducer 1a, and is connected
to a transmission signal circuit to be described later. And transmit an ultrasonic pulse signal.
[0010]
2 The ultrasonic wave receiver is made of the same material as the ultrasonic wave transmitter 1,
is connected to a wave receiving signal processing circuit to be described later, and receives a
drive signal, a wraparound signal and a reflected wave from an object.
[0011]
3
A transmission signal circuit is composed of a periodic oscillation circuit 3a, an oscillation circuit
3b, and a transmission amplification circuit 3c.
The periodic oscillation circuit 3a creates a pulse signal of a constant cycle, and outputs the pulse
signal to the oscillation circuit 3b and a first detection gate creation circuit to be described later.
The oscillation circuit 3b converts a pulse signal of a fixed cycle from the periodic oscillation
circuit 3a into an ultrasonic pulse signal S1 of a predetermined frequency and outputs the
ultrasonic pulse signal S1 to the transmission amplification circuit 3c.
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The transmission amplification circuit 3 c amplifies the ultrasonic pulse signal from the
oscillation circuit 3 b which is intermittently input, and outputs the amplified signal to the
ultrasonic transmission device 1.
[0012]
4
Reference numeral 4 denotes a wave receiving signal processing circuit, which comprises a wave
receiving amplification circuit 4a, a detection / waveform shaping circuit 4b, a comparator 4c, a
first detection gate generation circuit 4d, and a first detection signal processing circuit 4e.
The reception amplification circuit 4a receives the reception signal from the ultrasonic wave
receiver 2, amplifies it to a fixed level, and outputs it to the detection and waveform shaping
circuit 4b.
The detection and waveform shaping circuit 4b receives the signal S2 from the wave receiving
amplification circuit 4a, removes the high frequency component of the signal S2, extracts only
the envelope of the signal, shapes the waveform, and outputs it to the comparator 4c.
The comparator 4c detects the received wave signal output from the detection and waveform
shaping circuit 4b with a threshold value, and outputs a High signal S3 to the first detection
signal processing circuit 4e.
The first detection gate formation circuit 4d takes a signal from the periodic oscillation circuit 3a,
and forms a detection gate for detecting a reflected wave from an object received between
transmission and the next transmission, and generates a first detection signal processing circuit
4e. Output to
The first detection signal processing circuit 4e generates a high signal when the output from the
comparator 4c appearing between the detection gates generated by the first detection gate
generation circuit 4d is a high signal, and a low signal when the output from the comparator 4c
is a low signal. Output to means.
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[0013]
5 The first notification means includes an LED, a buzzer and the like, and operates when a High
signal is output from the first detection signal processing circuit 4e.
[0014]
6
The time monitor means includes a second detection gate generation circuit 6a, a second
detection signal processing circuit 6b, and a second notification means 6c.
The second detection gate generation circuit 6a takes a signal from the periodic oscillation circuit
3a, and generates a detection gate S4 having a predetermined time width at a timing within the
wraparound signal portion of the reception signal S2 in the normal operation state. It is output to
the processing circuit 6b. In this time width, the output end time of the wraparound signal of the
received wave signal S2 in the normal operation state, and the foreign matter adheres around the
ultrasonic wave transmitter 1 and the ultrasonic wave receiver 2, and the sensitivity of the
transmitted wave and received wave It is set between the output end time of the wraparound
signal from the comparator 4c when the decrease reaches the allowable limit of detection
performance. The second detection signal processing circuit 6b generates a second signal when
the output from the comparator 4c appearing between the detection gates S4 created by the
second detection gate creation circuit 6a is a high signal and a high signal when the output is a
low signal. Output to means 6c. The second notification unit 6c includes an LED, a buzzer, and
the like, and operates when the High signal is output from the second detection signal processing
circuit 6b. The second notification means 6c may be identical to or integral with the first
notification means 5. For example, in the case of using an LED, the signal levels from the first and
second detection signal processing circuits 4e and 6b are different. It is also possible to change
the color of light emission so that it can be identified from which notification.
[0015]
This system reports that an abnormal operation state, that is, a decrease in operation sensitivity
or a reduction in detection area A has occurred, by operating the second notification unit 6c.
[0016]
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Next, a second embodiment of the present invention will be described based on FIG.
The main part is in the time monitoring means 7. The members other than the main part are the
same as those of the first embodiment described above, and therefore, substantially the same
members are denoted by the same reference numerals and detailed description thereof will be
omitted.
[0017]
The time monitoring means 7 comprises a second detection gate generation circuit 7a, a second
detection signal processing circuit 7b, a third detection gate generation circuit 7c, a third
detection signal processing circuit 7d, and a second notification means 7e. The second detection
gate generation circuit 7a takes a signal from the periodic oscillation circuit 3a, generates a
detection gate S3 at a timing within the wraparound signal portion of the received wave signal in
the normal operation state, and outputs it to the second detection signal processing circuit 7b.
ing. The detection gate S3 is a detection gate formed by a third detection gate generation circuit
7c, which will be described later, between the output end time T1 of the wraparound signal in the
normal operation state and the output end time T2 of the wraparound signal in the abnormal
operation state. The timing is set so as not to overlap, and the output end time T2 of the
wraparound signal in the abnormal operation state is set. The second detection signal processing
circuit 7b outputs a low signal to the second notification unit 7e when the output from the
comparator 4c appearing between the detection gates S3 generated by the second detection gate
generation circuit 7a is a high signal, and a low signal. A High signal is output to the second
notification means 7e. The third detection gate creation circuit 7c takes a signal from the
periodic oscillation circuit 3a, creates a detection gate S4 at the timing within the wraparound
signal portion of the received wave signal in the normal operation state, and outputs it to the
third detection signal processing circuit 7d. ing. The detection gate S4 is overlapped with the
detection gate S3 created by the second detection gate creation circuit 7a between the output
end time T1 of the wraparound signal in the normal operation state and the output end time T2
of the wraparound signal in the abnormal operation state. It is set near the output end time T1 of
the wraparound signal in the normal operation state and the timing which does not occur. The
third detection signal processing circuit 7d outputs a low signal to the second notification unit 7e
when the output from the comparator 4c appearing between the detection gates S4 generated by
the third detection gate generation circuit 7c is a high signal, and a low signal. A High signal is
output to the second notification means 7e. The second notification unit 7e is formed of an LED,
a buzzer, etc., and is continuously output when the second detection signal processing circuit 7b
outputs a high signal, and intermittently when the third detection signal processing circuit 7d
outputs a high signal. Operate.
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[0018]
This device reports that an abnormal operating condition, that is, a decrease in operating
sensitivity or a reduction in detection area A is occurring, by intermittently operating the second
notification unit 7e, and that an abnormal operating condition has occurred, Notification is
performed by operating the second notification means 7e continuously.
[0019]
Next, a third embodiment of the present invention will be described based on FIG.
The main parts are the wave receiving amplifier circuit 8 of the wave receiving signal processing
circuit 4, the time monitoring means 9, and the detection area forming display means 10. The
members other than the main part are the same as in the first and second embodiments
described above, and therefore, substantially the same members are assigned the same reference
numerals and detailed explanations thereof will be omitted.
[0020]
The wave receiving amplification circuit 8 includes a manual gain adjustment volume 8a capable
of adjusting the amplification factor to the wave reception amplification circuit 4a of the first
embodiment. When the gain adjustment volume 8a is adjusted from a large amplification factor
to a small amplification factor, the detection area A of the reflected wave from the object received
between the transmission and the next transmission is narrowed. Further, the level of the
wraparound signal is reduced to shorten the output end time of the wraparound signal output
from the comparator 4c.
[0021]
The time monitoring means 9 is a modification of the time monitoring means 7 of the second
embodiment, and for example, two detection gate forming circuits (not shown) and detection
signal processing circuits (not shown) are additionally provided. The time monitoring means 9 is
formed by four detection gate generation circuits (not shown) between the output end time of the
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wraparound signal in the normal operation state and the output end time of the wraparound
signal in the abnormal operation state. The detection gates of are set at timings that do not
overlap.
[0022]
The detection area formation display means 10 has display tools L1, L2, L3, L4 comprising four
LEDs etc. provided corresponding to the four detection signal processing circuits, and from the
four detection signal processing circuits A drive signal is output to the display in response to a
High signal that is output appropriately.
[0023]
In this device, the detection area A is expanded or narrowed according to the adjustment of the
gain adjustment volume 8a, and the display tool 10a corresponding to the output end time of the
wraparound signal is operated to obtain the detection area A and the display tool 10a. Since the
action is associated, the size of the detection area A is known by recognizing the operating
display tool 10a.
For example, the display fixtures L1 and A4 are displayed on the display fixture L4 in A1 of the
detection area A shown in FIG. 4 (b).
[0024]
Next, a fourth embodiment of the present invention will be described based on FIG. This main
part is in the time monitoring means 11 and the heating means 12. The members other than the
main part are the same as those of the first embodiment described above, and therefore,
substantially the same members are denoted by the same reference numerals and detailed
description thereof will be omitted.
[0025]
The time monitoring means 11 is a modification of the time monitoring means 6 of the first
embodiment, and a second detection signal processing circuit (not shown) is formed by a second
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detection gate forming circuit (not shown). When the output from the comparator 4c appearing
between them is the high signal, the low signal is outputted to the heating means 12, and when
the output is the low signal, the high signal is outputted to the heating means 12. The heating
means 12 comprises a heater 12a incorporated in the vicinity of the outer end face of the
ultrasonic wave transmitter 1 and the horn portion 1b of the ultrasonic wave transmitter 2, and a
heater control signal circuit 12b. The heater control signal circuit 12b receives the High signal of
the time monitoring means 11, and outputs a drive signal for ON-OFF controlling the heater 12a.
[0026]
In this case, if the horn unit 1b etc. has snow or ice buildup on the water and there is a drop in
the sensitivity of the ultrasonic wave transmitter 1 and the ultrasonic wave transmitter 2, the
heater 12a is operated to heat snow and ice. Can be used to improve the reliability of use in
winter and snowy areas.
[0027]
According to the present invention, the ultrasonic sensor according to the present invention
detects the attenuation of the sneaking signal to notify the abnormality around the ultrasonic
wave transmitter and the ultrasonic wave receiver, that is, the abnormal operation state, by the
above-mentioned configuration. Therefore, it is possible to prevent use in an abnormal operation
state and to improve the reliability of use.
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