JPS645767B2 - - Google Patents
Info
- Publication number
- JPS645767B2 JPS645767B2 JP8462081A JP8462081A JPS645767B2 JP S645767 B2 JPS645767 B2 JP S645767B2 JP 8462081 A JP8462081 A JP 8462081A JP 8462081 A JP8462081 A JP 8462081A JP S645767 B2 JPS645767 B2 JP S645767B2
- Authority
- JP
- Japan
- Prior art keywords
- circuit
- oscillation
- amplitude
- detected
- transistor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 230000010355 oscillation Effects 0.000 claims description 54
- 238000001514 detection method Methods 0.000 claims description 16
- 239000003990 capacitor Substances 0.000 claims description 8
- 238000000926 separation method Methods 0.000 claims description 6
- 230000000694 effects Effects 0.000 description 7
- 239000002184 metal Substances 0.000 description 5
- 238000010586 diagram Methods 0.000 description 2
- 230000003321 amplification Effects 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 230000004043 responsiveness Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/94—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
- H03K17/945—Proximity switches
- H03K17/95—Proximity switches using a magnetic detector
- H03K17/952—Proximity switches using a magnetic detector using inductive coils
- H03K17/9537—Proximity switches using a magnetic detector using inductive coils in a resonant circuit
- H03K17/9542—Proximity switches using a magnetic detector using inductive coils in a resonant circuit forming part of an oscillator
- H03K17/9547—Proximity switches using a magnetic detector using inductive coils in a resonant circuit forming part of an oscillator with variable amplitude
Landscapes
- Electronic Switches (AREA)
Description
【発明の詳細な説明】
本発明は金属の近接の有無を検出する高周波発
振型の近接スイツチに関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high frequency oscillation type proximity switch that detects the presence or absence of metal.
回転体の回転数検出や回転角度位置の検出を回
転体に金属突片を設け回転体の回転に伴い近接ス
イツチ前面をよぎる金属突片を高周波発振形の近
接スイツチで検出しon−off信号を出力する方法
は公知である。そして高周波発振形近接スイツチ
回路の特性は例えば金属（被検出体）の非接近時
の定常発振状態から被検出体の近接により発振停
止に到る減衰振動波形の振動振幅を所定のレベル
比較設定値と比較し上記振動振幅がレベル比較設
定値を下まわつた時に出力を反転させることによ
り被検出体の近接を検出する。逆に被検出体が近
接状態から離間する時は発振開始から定常発振状
態に到る過渡的発振振幅を上記レベル比較設定値
と比較し上記振幅がレベル比較設定値より大とな
つた時に出力を反転させ近接スイツチから被検出
体が離間したことを検出するものである。従つ
て、実際例として近接、あるいは離間の瞬間から
出力反転が生ずるまでには発振回路の発振出力の
減衰や成長の時定数、更に初期条件に依存した時
間遅れが生ずるのを是認せざるを得なかつた。そ
して振幅の大小を判別するレベル比較設定値は
Ｓ／Ｎ、あるいは回路の安定性に伴う信頼性等か
ら定常発振振幅の略1/2程度に選び被検出体の近
接を検出するときには回路の減衰振動の時定数に
ほぼ等しい時間遅れとなるが、この時定数は近接
スイツチの検出コイルに被検出体を十分近接させ
れば非常に小さくでき、通常数μs程度にされ得る
ので実用上は無視できるものであつた。しかし、
被検出体の離間時には発振開始の振幅が外来雑音
や、素子自体が発生する雑音により決まるので発
振開始後レベル比較設定値にまで振幅が達するに
は発振回路の振幅成長の時定数の10倍ないし、30
倍程度の時間を要する。被検出体の非近接時の振
幅成長の時定数は被検出体が完全に離間した時に
最小となり、その値は被検出体の検出感度を設定
した時に決まり、被検出体の近接時のように小さ
な値にすることは出来ず、普通数10マイクロ・セ
カンド程度である。従つて、被検出体が離間して
出力が反転するまでには数100マイクロ・セカン
ドから数ミリ・セカンドの非常に長い時間遅れが
出る。更に上述の発振開始電圧を決定する雑音は
統計量であり、その波高は広く分布するので離間
を検出する時の時間遅れもその時の条件で異な
る。この様に従来の近接スイツチ回路は動作の時
間遅れや、時間遅れのゆらぎがあるため回転体の
回転数検出等に使用する場合には検出可能な回転
数はその時間遅れによつて制限され、また回転体
の角度位置の検出に使用する場合には近接時の情
報のみが有効で離間時の出力反転信号は上記時間
遅れのばらつきや、ゆらぎのために角度位置信号
が得られないという欠点があつた。 To detect the rotational speed and rotation angle position of the rotating body, a metal protrusion is installed on the rotating body, and a high-frequency oscillation type proximity switch detects the metal protrusion that crosses the front surface of the proximity switch as the rotating body rotates, and generates an on-off signal. The method of outputting is well known. The characteristics of a high frequency oscillation type proximity switch circuit are, for example, the vibration amplitude of a damped vibration waveform that changes from a steady oscillation state when a metal (object to be detected) does not approach to stopping oscillation due to the proximity of a detection object to a predetermined level comparison setting value. The proximity of the object to be detected is detected by inverting the output when the vibration amplitude falls below the level comparison set value. Conversely, when the object to be detected moves away from the close state, the transient oscillation amplitude from the start of oscillation to the steady oscillation state is compared with the level comparison set value, and when the above amplitude becomes larger than the level comparison set value, the output is output. This is to detect when the object to be detected has moved away from the proximity switch. Therefore, as a practical example, it must be acknowledged that from the moment of proximity or separation until output reversal occurs, there is a time delay depending on the time constant of the oscillation output decay and growth of the oscillation circuit, as well as the initial conditions. Nakatsuta. The level comparison setting value for determining the magnitude of the amplitude is selected to be approximately 1/2 of the steady oscillation amplitude due to S/N or reliability associated with circuit stability, etc. When detecting the proximity of the detected object, the circuit attenuation The time delay is approximately equal to the vibration time constant, but this time constant can be made very small by bringing the object to be detected sufficiently close to the detection coil of the proximity switch, and can usually be reduced to a few μs, so it can be ignored in practice. It was hot. but,
When the object to be detected is separated, the amplitude at which oscillation starts is determined by external noise and noise generated by the element itself, so in order for the amplitude to reach the level comparison set value after oscillation starts, it must be 10 times the time constant of the amplitude growth of the oscillation circuit. , 30
It takes about twice as long. The time constant of amplitude growth when the detected object is not close is the minimum when the detected object is completely separated, and its value is determined when the detection sensitivity of the detected object is set. It cannot be reduced to a small value; it is usually around 10 microseconds. Therefore, there is a very long time delay of several hundred microseconds to several milliseconds until the object to be detected moves away and the output is reversed. Furthermore, the noise that determines the oscillation start voltage described above is a statistical quantity, and its wave height is widely distributed, so the time delay when detecting separation also differs depending on the conditions at that time. In this way, conventional proximity switch circuits have a time delay in operation and fluctuations due to the time delay, so when used to detect the rotation speed of a rotating body, the detectable rotation speed is limited by the time delay. Furthermore, when used to detect the angular position of a rotating body, only the information when approaching is valid, and the output inverted signal when separating has the disadvantage that an angular position signal cannot be obtained due to the above-mentioned time delay variations and fluctuations. It was hot.
従つて、本発明は上記の欠点を除去するために
成されたもので、並列共振回路と、負性コンダク
タンス特性を有する能動回路と、バイアス電圧回
路とから構成される発振回路のバイアス電圧回路
のバイアス電圧に所定の周波数及び振幅を有する
交流電圧成分を持たせ被検出体離間後の発振開始
をランダムな雑音誘因に依存されず、バイアス電
圧回路のバイアス電圧の交流成分により発振回路
に発生する振幅から発振を開始させることにより
発振開始の時間遅れを減少せしめ、かつ遅れ時間
のゆらぎを排除することによつて高回転で回転す
る回転体の検出を可能とし、更に回転体の角度位
置検出に対しては被検出体離間時の出力もどり信
号も角度情報として有意な信号とすることが可能
な近接スイツチ回路を提供することを目的とす
る。 Therefore, the present invention has been made to eliminate the above-mentioned drawbacks, and is aimed at improving the bias voltage circuit of an oscillator circuit consisting of a parallel resonant circuit, an active circuit having negative conductance characteristics, and a bias voltage circuit. The bias voltage has an AC voltage component with a predetermined frequency and amplitude, so that the oscillation starts after separation from the object to be detected without depending on random noise factors, and the amplitude generated in the oscillation circuit by the AC component of the bias voltage of the bias voltage circuit. By starting oscillation from Another object of the present invention is to provide a proximity switch circuit in which an output return signal when a detected object is separated can also be used as a significant signal as angle information.
以下、本発明を図示の一実施例について説明す
る。第１図において、１は発振回路、２は所定の
比較レベルと前記発振回路１の発振振幅を比較し
その大小に応じた出力信号を発生する振幅比較回
路である。そして４は検出コイル、５は前記検出
コイル４と共に並列共振回路を形成するコンデン
サ、６はエミツタホロワ接続のトランジスタ、７
はそのエミツタ抵抗、８，９はトランジスタ６の
コレクタ出力電流に相当する電流を出力するカレ
ントミラー接続の２つのトランジスタ、３はバイ
アス電圧回路である。そのバイアス電圧回路３に
おいて、１０はエミツタホロワ接続のトランジス
タ、１１は前記トランジスタ１０のエミツタ抵
抗、１２は所定周波数、及び所定の振幅を有する
交流電圧源、１３はトランジスタ１０に一定の直
流ベースバイアスを与える直流バイアス回路であ
る。 Hereinafter, the present invention will be described with reference to an illustrated embodiment. In FIG. 1, 1 is an oscillation circuit, and 2 is an amplitude comparison circuit that compares the oscillation amplitude of the oscillation circuit 1 with a predetermined comparison level and generates an output signal according to the magnitude thereof. 4 is a detection coil; 5 is a capacitor forming a parallel resonant circuit together with the detection coil 4; 6 is an emitter follower-connected transistor; 7
is its emitter resistance, 8 and 9 are two current mirror connected transistors that output a current corresponding to the collector output current of transistor 6, and 3 is a bias voltage circuit. In the bias voltage circuit 3, 10 is a transistor with an emitter follower connection, 11 is an emitter resistance of the transistor 10, 12 is an AC voltage source having a predetermined frequency and a predetermined amplitude, and 13 is a voltage source that applies a constant DC base bias to the transistor 10. This is a DC bias circuit.
この様な構成からなる本発明の近接スイツチ回
路の動作について以下説明する。図示の回路にお
いて今、トランジスタ６のベース点Ａの電位が上
昇したとすると、そのエミツタ電位も上昇し、エ
ミツタ抵抗７を流れる、すなわち、トランジスタ
６のエミツタ電流は増加する。これに伴いコレク
タ電流はエミツタ電流とほぼ等しい分増加し、ト
ランジスタ８，９より成るカレントミラー回路を
on側に駆動する。この動作によつてトランジス
タ９からトランジスタ６のコレクタにコレクタ電
流に相当する電流が流れる。また、トランジスタ
６のベースとトランジスタ９のコレクタは共に接
続されているため、トランジスタ６のベース点Ａ
の電位を上昇させるとそのＡ点には前記Ａ点電位
に対応してトランジスタ９より更に電流が流れる
ようになり所定値に達し安定する。従つて、近接
スイツチ回路の被検出体を検出コイル４、コンデ
ンサ５とから成る並列共振回路側から発振回路１
のトランジスタ６のベースとトランジスタ９のコ
レクタとの接続点を見込んだアドミツタンスは負
性コンダクタンス性となり、その負性コンダクタ
ンス値はほぼトランジスタ６のエミツタ抵抗７の
抵抗値の逆数に等しい。一方、トランジスタ１０
はエミツタ抵抗１１と共にエミツタホロワを構成
するためトランジスタ１０のベース点Ｂの電位の
変化は電圧増幅率は１でトランジスタ１０のエミ
ツタに出力される。すなわち、トランジスタ１０
のベース点Ｂを交流電圧源１２で駆動することに
よりトランジスタ１０のエミツタには直流バイア
ス回路１３によりきまる直流電圧と、交流電圧源
１２による交流電圧が十分低い出力インピーダン
スで出力される。つまりバイアス電圧回路３は直
流電圧源と交流電圧源１２の直列回路となりこの
回路の出力電圧は検出コイル４とコンデンサ５の
接続点Ｃに印加される。従つて、本発明における
近接スイツチ回路の一実施例を交流的に見ると、
検出コイル４とコンデンサ５より成る並列共振回
路に直列に交流電圧源が接続され、この直列回路
に並列に負性コンダクタンスが接続されたことに
なる。さて、並列共振回路は損失を有するので振
動電圧が発生しても減衰する。しかし上記発振回
路１ではバイアス電圧回路３のインピーダンスは
十分小さいので並列共振回路に並列に負性コンダ
クタンスが接続されることになり並列共振回路の
損失、つまりコンダクタンス成分により消費され
る電力が回路の負性コンダクタンス成分により供
給される電力によつて賄われるため、実質的には
損失が負の並列共振回路が構成されバイアス電圧
回路３の交流電圧成分により端子間に発生する振
動電圧は増幅され発振が成長する。この発振は回
路の飽和等により非線形性であり、一定値にまで
成長し定常発振をする。 The operation of the proximity switch circuit of the present invention having such a configuration will be explained below. In the illustrated circuit, if the potential at the base point A of the transistor 6 rises, the emitter potential also rises, and the emitter current flowing through the emitter resistor 7, that is, the emitter current of the transistor 6 increases. Along with this, the collector current increases by an amount almost equal to the emitter current, and the current mirror circuit consisting of transistors 8 and 9 is activated.
Drive to the on side. Due to this operation, a current corresponding to the collector current flows from transistor 9 to the collector of transistor 6. Also, since the base of transistor 6 and the collector of transistor 9 are connected together, the base point A of transistor 6
When the potential of the transistor 9 is increased, a further current flows through the transistor 9 at the point A corresponding to the potential of the point A, reaching a predetermined value and becoming stable. Therefore, the object to be detected of the proximity switch circuit is connected to the oscillation circuit 1 from the side of the parallel resonant circuit consisting of the detection coil 4 and the capacitor 5.
The admittance considering the connection point between the base of the transistor 6 and the collector of the transistor 9 has negative conductance, and the value of the negative conductance is approximately equal to the reciprocal of the resistance value of the emitter resistor 7 of the transistor 6. On the other hand, transistor 10
constitutes an emitter follower together with the emitter resistor 11, so a change in the potential at the base point B of the transistor 10 is output to the emitter of the transistor 10 with a voltage amplification factor of 1. That is, transistor 10
By driving the base point B of the transistor 10 with the AC voltage source 12, a DC voltage determined by the DC bias circuit 13 and an AC voltage from the AC voltage source 12 are outputted to the emitter of the transistor 10 with sufficiently low output impedance. In other words, the bias voltage circuit 3 is a series circuit of a DC voltage source and an AC voltage source 12, and the output voltage of this circuit is applied to the connection point C between the detection coil 4 and the capacitor 5. Therefore, if one embodiment of the proximity switch circuit according to the present invention is viewed from an AC perspective,
An AC voltage source is connected in series to a parallel resonant circuit consisting of the detection coil 4 and the capacitor 5, and a negative conductance is connected in parallel to this series circuit. Now, since the parallel resonant circuit has a loss, even if an oscillating voltage is generated, it is attenuated. However, in the above oscillation circuit 1, the impedance of the bias voltage circuit 3 is sufficiently small, so a negative conductance is connected in parallel to the parallel resonant circuit, and the loss of the parallel resonant circuit, that is, the power consumed by the conductance component, is reduced to the negative conductance of the circuit. Since the electric power supplied by the conductance component effectively constitutes a parallel resonant circuit with negative loss, the oscillating voltage generated between the terminals by the AC voltage component of the bias voltage circuit 3 is amplified and oscillation is prevented. grow up. This oscillation is nonlinear due to circuit saturation, etc., and grows to a constant value, resulting in steady oscillation.
回路が発振状態の時に検出コイル４の近傍に被
検出体である金属が接近するとその近接効果によ
り発振回路の電力が消費される。すなわち、検出
コイルに並列に近接効果によるコンダクタンスが
接続されたことと等価になる。このように近接効
果による検出コイル４のコンダクタンスの増加に
より発振回路の全コンダクタンス、すなわち、能
動回路の負性コンダクタンスと並列共振回路の損
失と、近接効果によるコンダクタンスとの和が正
になる場合、損失が正となるので発振回路は減衰
振動を行い発振条件は停止に至る。被検出体が離
間すれば当然近接効果によるコンダクタンスは消
失するので発振回路１は全コンダクタンスが負と
なり再び発振を開始する。 When a metal object to be detected comes close to the detection coil 4 when the circuit is in an oscillating state, the power of the oscillation circuit is consumed due to the proximity effect. In other words, this is equivalent to connecting a conductance due to the proximity effect in parallel to the detection coil. If the total conductance of the oscillation circuit, that is, the sum of the negative conductance of the active circuit, the loss of the parallel resonant circuit, and the conductance due to the proximity effect, becomes positive due to the increase in the conductance of the detection coil 4 due to the proximity effect, then the loss becomes positive, so the oscillation circuit performs damped oscillation and the oscillation condition comes to a stop. If the object to be detected moves away, the conductance due to the proximity effect naturally disappears, so the oscillation circuit 1 has a negative total conductance and starts oscillating again.
上記発振回路１の発振周波数の振幅をトランジ
スタ６のエミツタに接続された振幅比較回路２で
比較レベル（第３図のVref）と比較する。ここ
での振幅比較レベルは発振振幅が回路の飽和等に
よる影響を受けない範囲で選ばれるが、通常は比
較の容易さ、Ｓ／Ｎの安定性などから略1V程度
に設定される。振幅比較回路２は発振振幅が比較
レベルに達しない場合は被検出体の近接があるも
のとし、例えば、ハイ（以下、“Ｈ”と略記する）
レベルの出力信号を発し、振幅が上記比較レベル
を越えると被検出体は近接していないものと判断
し、例えば、ロウ（以下、“Ｌ”と略記する）レ
ベルの信号を出力する。 The amplitude of the oscillation frequency of the oscillation circuit 1 is compared with a comparison level (Vref in FIG. 3) by an amplitude comparison circuit 2 connected to the emitter of the transistor 6. The amplitude comparison level here is selected within a range where the oscillation amplitude is not affected by circuit saturation, etc., but is usually set to about 1V for ease of comparison and S/N stability. If the oscillation amplitude does not reach the comparison level, the amplitude comparison circuit 2 assumes that the object to be detected is close, and, for example, indicates a high level (hereinafter abbreviated as "H").
If the amplitude exceeds the comparison level, it is determined that the object to be detected is not nearby, and a low (hereinafter abbreviated as "L") level signal is output, for example.
この様にして、本発明の一実施例は被検出体の
近接を検出することが可能となるが、ここでこの
回路の被検出体検出に対する応答性を第２図に示
す交流等価回路を用いて説明する。第２図におい
てＬは検出コイル４のインダクタンス、Ｃはコン
デンサ５の容量、GTは検出コイル４、およびコ
ンデンサ５からなるLc並列共振回路の損失、−Go
は能動回路の負性コンダクタンス、GMは被検出
体の近接により生ずるコンダクタンスVsはバイ
アス電圧回路３の交流成分、INは雑音電流源であ
る。 In this way, one embodiment of the present invention is capable of detecting the proximity of a detected object. Here, we will use an AC equivalent circuit shown in FIG. 2 to evaluate the responsiveness of this circuit to detecting a detected object. I will explain. In Fig. 2, L is the inductance of the detection coil 4, C is the capacitance of the capacitor 5, G T is the loss of the Lc parallel resonant circuit consisting of the detection coil 4 and the capacitor 5, -Go
is the negative conductance of the active circuit, G M is the conductance caused by the proximity of the object to be detected, Vs is the alternating current component of the bias voltage circuit 3, and I N is the noise current source.
今、近接状態にあつた被検出体が瞬間的に離間
した場合を考える。雑音電流源INの並列共振回路
帯域内の交流電圧成分の振幅をINｏ、周波数を
ωNとしバイアス回路３の交流電圧成分Vsの周波
数を並列共振回路の帯域幅内に設定し、その振幅
をVspとすると、離間の瞬間から時間ｔ後の発振
回路の発振振幅は(1)式で表わされる。 Now, let us consider a case where the object to be detected, which was in close proximity, momentarily moves away. The amplitude of the AC voltage component within the parallel resonant circuit band of the noise current source I N is I N o, the frequency is ω N , the frequency of the AC voltage component Vs of the bias circuit 3 is set within the bandwidth of the parallel resonant circuit, and Assuming that the amplitude is Vsp , the oscillation amplitude of the oscillation circuit after time t from the moment of separation is expressed by equation (1).
ここでΨN、Ψs、ψは定位相項でありωpは発振
速度でその周波数は凡そ１／√に等しい。(1)
式における第１項は雑音電流源INによる起電力、
第２項は交流電圧源Vsによる起電力、第３項は
成長振動成分である。この振動振幅が振幅の比較
レベル（第３図のVref）に達するのに要する時
間、すなわち、被検出体離間後振幅比較回路２の
出力が反転するまでの遅れ時間Ｔは雑音電流源IN
による起電力INｏ／（Gp−GT）が比較レベル
Vrefに比べ非常に小さく、また交流電圧源Vsに
よる振幅VsoGT／（Go−GT）が比較レベルVref
より十分小さくなる如く設定することによつて(2)
式で与えられる。 Here, Ψ N , Ψ s , and ψ are constant phase terms, and ω p is the oscillation speed and its frequency is approximately equal to 1/√. (1)
The first term in the equation is the electromotive force due to the noise current source I N ,
The second term is the electromotive force caused by the AC voltage source Vs, and the third term is the growth oscillation component. The time required for this vibration amplitude to reach the amplitude comparison level (Vref in Fig. 3), that is, the delay time T until the output of the amplitude comparison circuit 2 is inverted after the object to be detected is separated, is the noise current source I N
The electromotive force I N o / (G p − G T ) is the comparison level.
It is very small compared to Vref, and the amplitude VsoG T /(Go−G T ) due to the AC voltage source Vs is the comparison level Vref
By setting it to be sufficiently smaller than (2)
It is given by Eq.
さて、従来の一般に提案されている近接スイツ
チ回路（ここでは図示していない）ではその交流
等価回路は第２図の本発明の一実施例における交
流等価回路に比べ交流電圧源Vsを除去したもの
となる。そこで従来回路と、本発明の回路とを比
較すると、従来回路では(2)式中の交流電圧源Vs
の成分Vsoがないため時間遅れT1は(3)式となる。 Now, in the conventional generally proposed proximity switch circuit (not shown here), its AC equivalent circuit is one in which the AC voltage source Vs is removed compared to the AC equivalent circuit in the embodiment of the present invention shown in FIG. becomes. Therefore, when comparing the conventional circuit and the circuit of the present invention, it is found that in the conventional circuit, the AC voltage source Vs in equation (2)
Since there is no component Vso, the time delay T 1 becomes equation (3).
T1＝2c／Gp−GTlnVref／INp／（Gp−GT） …(3)
ここでINｏは電流雑音によるものでINp／（Go
−GT）は通常10-6〜10-9V程度であり、(3)式の
Vrefを略1Vとすれば、T1は発振回路の振幅成長
の時定数2c／（Go−GT）の15ないし20倍の時間
となる。これに対し、本発明の一実施例では
VsoGo≫INｏとなるように交流電圧源の振幅を設
定することにより遅れ時間は第３図に示す如く
T2＝2c／Go−GTlnVref／GoVso／（Go−GT）…(4)
で表わされる。例えばGoVso／（Go−GT）を10
ミリボルトになるように交流電圧源Vsを設定す
れば(4)式の対数部の値は比較レベルVrefを略1V
とした場合、約4.6Vとなり遅れ時間T2は発振回
路の振幅成長の時定数2c／（Go−GT）の4.6倍と
なり、従来回路の遅れ時間T1に比べ略1/3ないし
１／４に短縮されたことになる。更に従来回路では
発振開始の振幅は雑音電流源INの振幅できまるも
のであり、雑音電流はランダムな雑音でその波高
はガウス分布的分布をするものであるから(3)式の
対数部はある値を中心として分布をすることにな
る。つまり発振おくれ時間T1の値は一定値では
なく、ゆらぎを持つものであるから確率的には発
振回路の振幅成長の時定数の30倍、40倍という大
きな時間遅れとなる場合も存在する。従つて、従
来回路で回転数検出を行う場合、この最大の遅れ
時間を見込んで回転物検出等による最高使用可能
な回転数が決められるという欠点があつた。 T 1 = 2c/G p −G T lnVref/I Np / (G p − G T ) …(3) Here, I No is due to current noise, and I Np / (Go
−G T ) is usually about 10 -6 to 10 -9 V, and the equation (3)
If Vref is approximately 1V, T1 is 15 to 20 times the time constant 2c/(Go-G T ) of the amplitude growth of the oscillation circuit. In contrast, in one embodiment of the present invention
By setting the amplitude of the AC voltage source so that VsoGo≫I No , the delay time can be calculated as shown in Figure 3: T 2 = 2c/Go-G T lnVref/GoVso/(Go-G T )...(4 ). For example, GoVso/(Go−G T ) is 10
If the AC voltage source Vs is set so that the voltage is millivolt, the value of the logarithmic part of equation (4) will be approximately 1V compared to the comparison level Vref.
In this case, the result is approximately 4.6V, and the delay time T 2 is 4.6 times the time constant 2c/(Go − G T ) of the amplitude growth of the oscillation circuit, which is approximately 1/3 or 1/3 compared to the delay time T 1 of the conventional circuit. It has been shortened to 4. Furthermore, in the conventional circuit, the amplitude of the start of oscillation is determined by the amplitude of the noise current source I N , and since the noise current is random noise and its wave height has a Gaussian distribution, the logarithmic part of equation (3) is The distribution will be centered around the value. In other words, since the value of the oscillation delay time T 1 is not a constant value but has fluctuations, there are cases where the time delay is as large as 30 or 40 times the time constant of the amplitude growth of the oscillation circuit. Therefore, when detecting the rotation speed using the conventional circuit, there was a drawback in that the maximum usable rotation speed was determined by detecting a rotating object, etc., taking into account this maximum delay time.
従つて、本発明では交流電圧源Vsの振幅Vso
はバイアス回路３の交流電圧源１２で決められる
ため、常に一定値とすることが可能である。した
がつて遅れ時間も一定でゆらぎは全く生じない。
ここで従来回路と本発明の一実施例の発振振幅の
変化の様子を第３図に示した。図中ａは被検出体
の近接あるいは離間を示し、ｂは従来回路の発振
振幅、ｃは従来回路での出力波形、ｄ，ｅは本発
明の一実施例の発振振幅、および出力波形を示
す。図示の如く本発明による結果は時間遅れが
T1からT2へ改善されていることが判る。 Therefore, in the present invention, the amplitude Vso of the AC voltage source Vs
Since is determined by the AC voltage source 12 of the bias circuit 3, it is possible to always maintain a constant value. Therefore, the delay time is constant and no fluctuation occurs at all.
Here, FIG. 3 shows how the oscillation amplitude changes in the conventional circuit and one embodiment of the present invention. In the figure, a indicates the proximity or separation of the object to be detected, b indicates the oscillation amplitude of the conventional circuit, c indicates the output waveform of the conventional circuit, and d and e indicate the oscillation amplitude and output waveform of an embodiment of the present invention. . As shown in the figure, the result of the present invention is that there is no time delay.
It can be seen that there has been an improvement from T 1 to T 2 .
以上の様に本発明によれば検出コイルとコンデ
ンサより成る並列共振回路に別に設けた所定の周
波数、所定の振幅を有するバイアス電圧を与える
ことによつて被検出体離間後の発振開始条件を周
囲の雑音等に依存されず一定の振幅から行われる
様にしたので被検出体離間後の出力反転までの時
間遅れが大幅に改善され、また、その遅れ時間も
常に一定になるので、例えば高回転で回転する回
転体の回転検出を行なうことが可能となる。ま
た、回転体の角度位置検出に当つては時間遅れが
一定であることから被検出体離間時の変化信号も
十分角度位置信号として利用できる等、高速動
作、高安定度の近接スイツチを容易に得ることが
出来る顕著な効果がある。 As described above, according to the present invention, by applying a separately provided bias voltage having a predetermined frequency and a predetermined amplitude to the parallel resonant circuit consisting of the detection coil and the capacitor, the oscillation start condition after the object to be detected is separated can be adjusted to the surroundings. Since the detection is performed from a constant amplitude without depending on the noise etc. of It becomes possible to detect the rotation of a rotating body. In addition, since the time delay is constant when detecting the angular position of a rotating body, the change signal when the object to be detected is separated can be used as an angular position signal, making it easy to create a high-speed, high-stability proximity switch. There are significant effects that can be achieved.
第１図は本発明の一実施例を示す近接スイツチ
回路の構成図、第２図はその交流等価回路、第３
図は本発明の作用効果を説明する要部の波形図で
ある。
１……発振回路、２……振幅比較回路、３……
バイアス電圧回路。
FIG. 1 is a block diagram of a proximity switch circuit showing one embodiment of the present invention, FIG. 2 is its AC equivalent circuit, and FIG.
The figure is a waveform diagram of the main part explaining the effect of the present invention. 1...Oscillation circuit, 2...Amplitude comparison circuit, 3...
Bias voltage circuit.
Claims (1)
共振回路を含む発振回路と、前記発振回路からの
出力信号と予め設定された比較レベルとの比較に
より被検出体の近接又は離間を検出する振幅比較
回路とを備えた近接スイツチ回路において、前記
発振回路の出力信号成分のうち雑音電流源に関す
る成分を無視し得るに充分な交流電圧成分を付与
することが可能なバイアス電圧回路を、前記並列
共振回路に直列接続し、しかも前記発振回路に含
まれる能動回路の負性コンダクタンスが、前記並
列回路及びバイアス電圧回路の直列接続体に対し
並列接続となるように構成したことを特徴とする
近接スイツチ回路。1. An oscillation circuit including a parallel resonant circuit composed of a detection coil and a capacitor, and an amplitude comparison circuit that detects proximity or separation of a detected object by comparing an output signal from the oscillation circuit with a preset comparison level. In the proximity switch circuit, a bias voltage circuit capable of applying an AC voltage component sufficient to ignore a component related to the noise current source among the output signal components of the oscillation circuit is connected in series to the parallel resonant circuit. 1. A proximity switch circuit, characterized in that the negative conductance of the active circuit included in the oscillation circuit is connected in parallel to the series connection of the parallel circuit and the bias voltage circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8462081A JPS57199331A (en) | 1981-06-02 | 1981-06-02 | Proximity switch circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8462081A JPS57199331A (en) | 1981-06-02 | 1981-06-02 | Proximity switch circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS57199331A JPS57199331A (en) | 1982-12-07 |
| JPS645767B2 true JPS645767B2 (en) | 1989-01-31 |
Family
ID=13835725
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8462081A Granted JPS57199331A (en) | 1981-06-02 | 1981-06-02 | Proximity switch circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS57199331A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9178361B2 (en) * | 2012-09-27 | 2015-11-03 | ConvenientPower, Ltd. | Methods and systems for detecting foreign objects in a wireless charging system |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5588227A (en) * | 1978-12-26 | 1980-07-03 | Omron Tateisi Electronics Co | Proximity switch |
-
1981
- 1981-06-02 JP JP8462081A patent/JPS57199331A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS57199331A (en) | 1982-12-07 |
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