JPH02218983A - Ultrasonic sensor - Google Patents
Ultrasonic sensorInfo
- Publication number
- JPH02218983A JPH02218983A JP4130789A JP4130789A JPH02218983A JP H02218983 A JPH02218983 A JP H02218983A JP 4130789 A JP4130789 A JP 4130789A JP 4130789 A JP4130789 A JP 4130789A JP H02218983 A JPH02218983 A JP H02218983A
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- short
- signal
- ultrasonic
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- 238000001514 detection method Methods 0.000 claims abstract description 17
- 230000005540 biological transmission Effects 0.000 claims abstract description 15
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000003321 amplification Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
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- Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
Abstract
Description
【発明の詳細な説明】
〔発明の分野〕
本発明は超音波振動子を断続的に駆動することによって
物体を検知する反射型の超音波センサに関するものであ
る。DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a reflection type ultrasonic sensor that detects an object by intermittently driving an ultrasonic transducer.
従来超音波センサとしては所定間隔毎に一定方向に超音
波を発振し、その反射波を受波するようにした反射型の
超音波センサが知られている。このような超音波センサ
は、超音波振動子を所定時間駆動し、その後超音波振動
子を受信用素子として使用して反射波信号によって物体
の有無や物体までの距離を検出するようにしている。し
かしながら超音波振動子の駆動直後は超音波振動子の振
動が徐々に低下するいわゆる残響が生じるため、残響時
間に反射波が得られる近距離の物体を検出することが困
難であった。2. Description of the Related Art As a conventional ultrasonic sensor, a reflection type ultrasonic sensor is known, which oscillates ultrasonic waves in a fixed direction at predetermined intervals and receives the reflected waves. Such an ultrasonic sensor drives an ultrasonic transducer for a predetermined period of time, and then uses the ultrasonic transducer as a receiving element to detect the presence or absence of an object and the distance to the object based on reflected wave signals. . However, immediately after the ultrasonic transducer is driven, so-called reverberation, in which the vibration of the ultrasonic transducer gradually decreases, occurs, making it difficult to detect objects at a short distance from which reflected waves can be obtained during the reverberation time.
そこで従来より残響時間中は閾値を高くし残響が小さく
なれば閾値を低くすることによって残響レベルを越える
物体を検出するようにしたり、残響に合わせて閾値を徐
々に低下させるようにした超音波センサが提案されてい
る。Therefore, conventional ultrasonic sensors have been designed to detect objects that exceed the reverberation level by setting a high threshold during the reverberation time and lowering the threshold when the reverberation becomes small, or by gradually lowering the threshold in accordance with the reverberation. is proposed.
しかしながらこのような従来の超音波センサによれば、
至近距離の物体は残響レベルを越える反射レベルを有す
る物体でなければ検出することができないという問題点
があった。However, according to such conventional ultrasonic sensors,
There is a problem in that objects at close range cannot be detected unless the object has a reflection level that exceeds the reverberation level.
本願の請求項１及び２の発明はこのような従来の超音波
センサの問題点に鑑みてなされたものであって、超音波
振動子の残Ｃを短時間で停止させることによって至近距
離の物体を検出できるようにすることを技術的課題とす
る。The inventions of Claims 1 and 2 of the present application have been made in view of the problems of conventional ultrasonic sensors, and are capable of detecting objects at close range by stopping the residual C of the ultrasonic transducer in a short time. The technical challenge is to make it possible to detect.
本願の請求項１の発明は超音波振動子を断続的に駆動し
、超音波の反射波信号に基づいて物体を検知する超音波
センサであって、所定時間毎に送波ゲート信号を発生し
、超音波振動子を駆動する送波ゲート発生回路と、送波
ゲート信号終了後に所定時間駆動され所定時間の短絡ゲ
ート信号を発生する短絡ゲート発生回路と、短絡ゲート
発生回路の出力により超音波振動子の両端を短絡する短
絡手段と、超音波振動子より得られる受波信号を検波す
る検波回路と、検波回路の出力を閾値電圧発生回路の閾
値によって弁別し反射波を検出する比較回路と、を具備
することを特徴とするものである。The invention of claim 1 of the present application is an ultrasonic sensor that intermittently drives an ultrasonic transducer and detects an object based on reflected ultrasonic wave signals, and generates a wave transmission gate signal at predetermined time intervals. , a wave transmission gate generation circuit that drives the ultrasonic transducer, a short circuit gate generation circuit that is driven for a predetermined period of time after the transmission gate signal ends, and generates a short circuit gate signal for a specified period of time, and an ultrasonic vibration generated by the output of the short circuit gate generation circuit. a detection circuit that detects a received signal obtained from the ultrasonic transducer; a comparison circuit that discriminates the output of the detection circuit based on a threshold of a threshold voltage generation circuit and detects a reflected wave; It is characterized by comprising the following.
本願の請求項２の発明は請求項１の短絡手段に代えて短
絡ゲート発生回路の出力により超音波振動子の両端を所
定の抵抗値で短絡する負荷抵抗手段としたものである。The invention according to claim 2 of the present application replaces the short-circuiting means according to claim 1 with load resistance means that short-circuits both ends of the ultrasonic transducer with a predetermined resistance value by the output of the short-circuiting gate generating circuit.
このような特徴を有する本願の請求項１又は２の発明に
よれば、超音波を駆動した直後に短絡ゲート発生回路が
一定時間動作し、超音波振動子の両端を短絡させ又はそ
の両端に直列に抵抗を接続するようにしている。こうす
れば残響が極めて短時間で終了し、又そのレベルも大幅
に低下することとなる。従って至近距離の物体からの反
射波レベルを容易に識別することができる。According to the invention of claim 1 or 2 of the present application having such features, the short-circuit gate generation circuit operates for a certain period of time immediately after driving the ultrasonic wave, and short-circuits both ends of the ultrasonic transducer or connects the ultrasonic transducer in series with both ends. I am trying to connect a resistor to. In this way, the reverberation will end in an extremely short period of time, and its level will also be significantly reduced. Therefore, the level of reflected waves from objects at close range can be easily identified.
そのため本願の請求項１及び２の発明によれば、残響が
短時間で停止するため超音波センサの近傍に物体が存在
し、駆動直後に反射波が得られる場合にも反射波を識別
することが可能となる。従って超音波センサに近い至近
距離の物体を確実に検出することができ、所定範囲で不
惑帯を生じることもなくなり、物体検出の信頼性を向上
させることが可能となる。Therefore, according to the inventions of Claims 1 and 2 of the present application, since the reverberation stops in a short time, it is possible to identify the reflected wave even when an object exists near the ultrasonic sensor and the reflected wave is obtained immediately after the ultrasonic sensor is driven. becomes possible. Therefore, it is possible to reliably detect an object at a close distance near the ultrasonic sensor, and there is no possibility of a dead zone occurring in a predetermined range, making it possible to improve the reliability of object detection.
第１図は本発明の一実施例による超音波センサの構成を
示すブロック図である。本図において送波ゲート発生回
路１は所定のタイミングで超音波振動子を駆動する送波
ゲート信号を発生するものであって、その出力は短絡ゲ
ート発生回路２及び駆動回路３に与えられる。駆動回路
３は送波ゲート発生回路１より送波ゲート信号が与えら
れる間に超音波振動子４を駆動するものである。又短絡
ゲート発生回路２は送波ゲート信号の直後に残響が生じ
る所定時間短絡ゲート信号を発生するものであって、そ
の出力はアナログスイッチ５に与えられる。アナログス
イッチ５は超音波振動子４の両端に並列に接続されてお
り、通常の動作ではオフ状態、短絡ゲート信号が加われ
ばオン状態となって超音波振動子４０両端を短絡する短
絡手段である。さて超音波振動子４の出力は増幅回路６
にも与えられる。増幅回路６は送波ゲート発生回路１よ
り与えられる送波のタイミング期間を除いて超音波振動
子４から得られる超音波信号を増幅するものであり、そ
の出力を検波回路７に与える。FIG. 1 is a block diagram showing the configuration of an ultrasonic sensor according to an embodiment of the present invention. In the figure, a wave transmission gate generation circuit 1 generates a wave transmission gate signal for driving an ultrasonic transducer at a predetermined timing, and its output is given to a short circuit gate generation circuit 2 and a drive circuit 3. The drive circuit 3 drives the ultrasonic transducer 4 while receiving a wave transmission gate signal from the wave transmission gate generation circuit 1. Further, the shorting gate generating circuit 2 generates a shorting gate signal for a predetermined period of time in which reverberation occurs immediately after the transmission gate signal, and its output is given to the analog switch 5. The analog switch 5 is connected in parallel to both ends of the ultrasonic transducer 4, and is in an OFF state during normal operation, but becomes an ON state when a short circuit gate signal is applied, and serves as a short-circuiting means that short-circuits both ends of the ultrasonic transducer 40. . Now, the output of the ultrasonic transducer 4 is the amplifier circuit 6
It is also given to The amplification circuit 6 amplifies the ultrasonic signal obtained from the ultrasonic transducer 4 except for the timing period of wave transmission given by the wave transmission gate generation circuit 1, and provides its output to the detection circuit 7.
検波回路７は受波した超音波を検波して包路線信号を得
るものであって、その出力は比較回路８に与えられてい
る。比較回路８は送波ゲート発生回路１及び短絡ゲート
発生回路２よりタイミング信号が与えられ、短絡ゲート
終了後に次の送波ゲート信号が発生するまでの間に検波
回路７より得られる信号を所定の閾値レベルと比較する
ものであって、閾値を越える信号を出力回路９に与える
。The detection circuit 7 detects the received ultrasonic wave to obtain an envelope signal, and its output is given to the comparison circuit 8. The comparator circuit 8 receives timing signals from the transmitting gate generating circuit 1 and the shorting gate generating circuit 2, and converts the signal obtained from the detecting circuit 7 into a predetermined signal after the shorting gate ends until the next transmitting gate signal is generated. It is compared with a threshold level, and a signal exceeding the threshold is given to the output circuit 9.
出力回路９は比較出力に基づいて物体検知信号を外部に
出力するものである。The output circuit 9 outputs an object detection signal to the outside based on the comparison output.
次に本実施例の動作について第２図ｆａ）、 （ｂ）及
び第３図を参照しつつ説明する。まず第２図はこの超音
波センサの前方に超音波振動子を配置し、その出力を増
幅して観測された残響を示している。Next, the operation of this embodiment will be explained with reference to FIGS. 2fa) and 3(b) and FIG. First, FIG. 2 shows the reverberation observed by placing an ultrasonic transducer in front of this ultrasonic sensor and amplifying its output.
短絡ゲート発生回路２よりアナログスイッチ５によって
超音波振動子４の両端を短絡しない場合には、第２図（
ａ）に残響の包絡線を示すように送波停止後残響が長時
間に渡って継続する。ここで残響を元の振動レベルから
振幅が９０％減衰するまでの時間と考えれば、例えば第
２図（ａ）では１６０１１ｓが残響時間となっている。If both ends of the ultrasonic transducer 4 are not short-circuited by the analog switch 5 from the short-circuit gate generation circuit 2, the circuit shown in FIG.
As shown in the reverberation envelope in a), the reverberation continues for a long time after transmission stops. If reverberation is considered to be the time it takes for the amplitude to attenuate by 90% from the original vibration level, then, for example, in FIG. 2(a), the reverberation time is 16011 seconds.
これに対して短絡ゲート発生回路２より超音波振動子４
を駆動した後アナログスイッチ５によってその両端を短
絡するように制御すれば、第２図（ｂ）に示すように残
響時間は９０μｓとなり短時間で残響を大幅に低減する
ことができる。On the other hand, the short circuit gate generating circuit 2 causes the ultrasonic vibrator 4 to
If, after driving, the analog switch 5 is used to short-circuit both ends, the reverberation time will be 90 μs, as shown in FIG. 2(b), and reverberation can be significantly reduced in a short period of time.
次に本実施例の動作についてタイムチャートを参照しつ
つ説明する。第３図（ａ）は送波ゲート発生回路１より
発生する送波ゲート信号であり、その出力に基づいて駆
動回路３より超音波振動子４が駆動され第３図（Ｃ）に
示すような超音波振動電圧が発生する。そして超音波振
動子４の駆動後は第３図（′ｂ）に示すように短絡ゲー
ト発生回路２より一定時間の短絡ゲート信号が発生して
アナログスイッチ５を閉成する。従って第３図（Ｃ１に
示すように超音波振動子４は前述したように残響が極め
て短時間で停止することとなる。第３図（Ｃ）において
破線で示す信号はアナログスイッチを用いない従来の超
音波振動子４の残響を示すものである。さてこのとき第
３図（Ｃ）に示すように超音波センサの近傍に反射物体
が位置する場合には、超音波振動子４の駆動直後に反射
波が得られる。この信号が超音波振動子４より得られ増
幅回路６によって増幅されて検波回路７に与えられる。Next, the operation of this embodiment will be explained with reference to time charts. FIG. 3(a) shows the transmitting gate signal generated by the transmitting gate generating circuit 1. Based on the output, the ultrasonic transducer 4 is driven by the driving circuit 3 to generate the signal as shown in FIG. 3(C). Ultrasonic vibration voltage is generated. After the ultrasonic transducer 4 is driven, the short circuit gate generating circuit 2 generates a short circuit gate signal for a certain period of time to close the analog switch 5, as shown in FIG. 3('b). Therefore, as shown in FIG. 3 (C1), the reverberation of the ultrasonic transducer 4 stops in an extremely short period of time as described above. This shows the reverberation of the ultrasonic transducer 4.At this time, if a reflective object is located near the ultrasonic sensor as shown in FIG. A reflected wave is obtained.This signal is obtained from the ultrasonic transducer 4, amplified by the amplifier circuit 6, and given to the detection circuit 7.
そして検波回路７によりその包路線信号が検波されて比
較回路８に与えられる。従って比較回路８は短絡ゲート
の終了後に得られる検波回路７の出力を所定の閾値と比
較することによって第３図（ｅ）に示すような出力が得
られる。この信号は出力回路９に伝えられ、第３図（ｆ
ｌに示すように物体検知信号として外部に出力される。Then, the envelope signal is detected by the detection circuit 7 and provided to the comparison circuit 8. Therefore, the comparator circuit 8 compares the output of the detection circuit 7 obtained after the completion of the short gate with a predetermined threshold value, thereby obtaining an output as shown in FIG. 3(e). This signal is transmitted to the output circuit 9 and is shown in FIG.
The signal is output to the outside as an object detection signal as shown in FIG.
このように本発明によれば、残響を短時間で停止させる
ことによって至近距離の物体を検出するようにしている
。As described above, according to the present invention, an object at a close distance is detected by stopping reverberation in a short time.
次に第４図は本願の請求項２の発明を具体化した実施例
を示すものである。本実施例においては前述した第１実
施例と同一部分は同一符号を付している。本実施例では
超音波振動子４を直接短絡したときに流れる過大電流を
防止して超音波振動子を保護するためにアナログスイッ
チ５に負荷抵抗Ｒを設けるようにしたものである。本実
施例においてアナログスイッチ５及び抵抗は超音波振動
子の両端を所定の抵抗値を短絡する負荷抵抗手段を構成
している。その他の構成及び動作は前述した第１実施例
と同様である。Next, FIG. 4 shows an embodiment embodying the invention of claim 2 of the present application. In this embodiment, the same parts as those in the first embodiment described above are given the same reference numerals. In this embodiment, the analog switch 5 is provided with a load resistor R in order to protect the ultrasonic transducer by preventing an excessive current flowing when the ultrasonic transducer 4 is directly short-circuited. In this embodiment, the analog switch 5 and the resistor constitute load resistance means that short-circuits both ends of the ultrasonic transducer to a predetermined resistance value. Other configurations and operations are similar to those of the first embodiment described above.
第１図は本売明の一実施例による超音波センサの全体構
成を示すブロック図、第２図（ａ）、第２図（ｂ）は本
発明の効果を確認するためにアナログスイッチの有無に
よる残響の変化を示すグラフ、第３図は本実施例の動作
時の各部の波形を示すタイムチャート、第４図は本願の
第２実施例のブロック図である。
１−・−送波ゲート発生回路 ２−−−−−・−短絡
ゲート発生回路 ３−・−・・駆動回路 ４−・・
−・−超音波振動子
５−−−−−−−アナログスイッチ
７−・−・・〜検波
回路
８・−一一一一一比較回路
９−・−−−−一出力回路FIG. 1 is a block diagram showing the overall configuration of an ultrasonic sensor according to an embodiment of the present invention, and FIGS. 2(a) and 2(b) show the presence and absence of an analog switch in order to confirm the effects of the present invention. FIG. 3 is a time chart showing waveforms of various parts during operation of this embodiment, and FIG. 4 is a block diagram of a second embodiment of the present application. 1-.-Transmission gate generation circuit 2-------Short gate generation circuit 3-.--Drive circuit 4-.
---Ultrasonic transducer 5--------Analog switch 7----Detection circuit 8--11-11 Comparison circuit 9----1 Output circuit
Claims (2)
信号に基づいて物体を検知する超音波センサであって、 所定時間毎に送波ゲート信号を発生し、前記超音波振動
子を駆動する送波ゲート発生回路と、前記送波ゲート信
号終了後に所定時間駆動され所定時間の短絡ゲート信号
を発生する短絡ゲート発生回路と、 前記短絡ゲート発生回路の出力により前記超音波振動子
の両端を短絡する短絡手段と、 前記超音波振動子より得られる受波信号を検波する検波
回路と、 前記検波回路の出力を前記閾値電圧発生回路の閾値によ
って弁別し反射波を検出する比較回路と、を具備するこ
とを特徴とする超音波センサ。(1) An ultrasonic sensor that intermittently drives an ultrasonic vibrator and detects an object based on reflected ultrasonic wave signals, which generates a wave transmission gate signal at predetermined time intervals and detects the ultrasonic vibration. a short-circuit gate generation circuit that is driven for a predetermined time after the end of the wave-transmission gate signal to generate a short-circuit gate signal for a predetermined time; and an output of the short-circuit gate generation circuit that drives the ultrasonic transducer. a detection circuit that detects a received signal obtained from the ultrasonic transducer; and a comparison circuit that discriminates the output of the detection circuit based on the threshold of the threshold voltage generation circuit and detects a reflected wave. An ultrasonic sensor comprising:
信号に基づいて物体を検知する超音波センサであって、 所定時間毎に送波ゲート信号を発生し、前記超音波振動
子を駆動する送波ゲート発生回路と、前記送波ゲート信
号終了後に所定時間駆動され所定時間の短絡ゲート信号
を発生する短絡ゲート発生回路と、 前記短絡ゲート発生回路の出力により前記超音波振動子
の両端を所定の抵抗値で短絡する負荷抵抗手段と、 前記超音波振動子より得られる受波信号を検波する検波
回路と、 前記検波回路の出力を前記閾値電圧発生回路の閾値によ
って弁別し反射波を検出する比較回路と、を具備するこ
とを特徴とする超音波センサ。(2) An ultrasonic sensor that intermittently drives an ultrasonic vibrator to detect an object based on a reflected ultrasonic wave signal, which generates a wave transmission gate signal at predetermined time intervals, and generates the ultrasonic vibration a short-circuit gate generation circuit that is driven for a predetermined time after the end of the wave-transmission gate signal to generate a short-circuit gate signal for a predetermined time; and an output of the short-circuit gate generation circuit that drives the ultrasonic transducer. load resistance means that short-circuits both ends of the ultrasonic transducer with a predetermined resistance value; a detection circuit that detects a received signal obtained from the ultrasonic transducer; and an output of the detection circuit that is discriminated and reflected by a threshold value of the threshold voltage generation circuit. An ultrasonic sensor comprising: a comparison circuit that detects waves.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4130789A JPH02218983A (en) | 1989-02-20 | 1989-02-20 | Ultrasonic sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4130789A JPH02218983A (en) | 1989-02-20 | 1989-02-20 | Ultrasonic sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02218983A true JPH02218983A (en) | 1990-08-31 |
Family
ID=12604838
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4130789A Pending JPH02218983A (en) | 1989-02-20 | 1989-02-20 | Ultrasonic sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02218983A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2022511179A (en) * | 2018-05-21 | 2022-01-31 | エコー イメージング，インク． | Ultrasonic transducer with Q value reduction |
| US11774280B2 (en) | 2018-04-11 | 2023-10-03 | Exo Imaging, Inc. | Imaging devices having piezoelectric transceivers |
| US11794209B2 (en) | 2019-09-12 | 2023-10-24 | Exo Imaging, Inc. | Increased MUT coupling efficiency and bandwidth via edge groove, virtual pivots, and free boundaries |
| US11819881B2 (en) | 2021-03-31 | 2023-11-21 | Exo Imaging, Inc. | Imaging devices having piezoelectric transceivers with harmonic characteristics |
| US11986350B2 (en) | 2016-12-04 | 2024-05-21 | Exo Imaging, Inc. | Imaging devices having piezoelectric transducers |
| US12000728B2 (en) | 2018-04-11 | 2024-06-04 | Exo Imaging, Inc. | Asymmetrical ultrasound transducer array |
-
1989
- 1989-02-20 JP JP4130789A patent/JPH02218983A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11986350B2 (en) | 2016-12-04 | 2024-05-21 | Exo Imaging, Inc. | Imaging devices having piezoelectric transducers |
| US11774280B2 (en) | 2018-04-11 | 2023-10-03 | Exo Imaging, Inc. | Imaging devices having piezoelectric transceivers |
| US12000728B2 (en) | 2018-04-11 | 2024-06-04 | Exo Imaging, Inc. | Asymmetrical ultrasound transducer array |
| JP2022511179A (en) * | 2018-05-21 | 2022-01-31 | エコー イメージング，インク． | Ultrasonic transducer with Q value reduction |
| US11794209B2 (en) | 2019-09-12 | 2023-10-24 | Exo Imaging, Inc. | Increased MUT coupling efficiency and bandwidth via edge groove, virtual pivots, and free boundaries |
| US11998950B2 (en) | 2019-09-12 | 2024-06-04 | Exo Imaging, Inc. | Increased MUT coupling efficiency and bandwidth via edge groove, virtual pivots, and free boundaries |
| US11819881B2 (en) | 2021-03-31 | 2023-11-21 | Exo Imaging, Inc. | Imaging devices having piezoelectric transceivers with harmonic characteristics |
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