JP5980111B2

JP5980111B2 - Photoelectric sensor

Info

Publication number: JP5980111B2
Application number: JP2012287779A
Authority: JP
Inventors: 永幸佐藤; 知広高宮
Original assignee: Azbil Corp
Current assignee: Azbil Corp
Priority date: 2012-12-28
Filing date: 2012-12-28
Publication date: 2016-08-31
Anticipated expiration: 2032-12-28
Also published as: JP2014131170A

Description

この発明は、受光量を電気信号に変換してコンパレータで閾値判定する光電センサにおいて、特に感度調整に関するものである。 The present invention particularly relates to sensitivity adjustment in a photoelectric sensor that converts a received light amount into an electrical signal and determines a threshold value by a comparator.

従来の光電センサは、投光器からの投光パルスを受光器で受光して電気信号に変換し増幅して受光信号を出力する。この受光信号が閾値を超えた場合にコンパレータからパルスを出力し、アップダウンカウンタが、パルス入力の都度カウントアップし、それ以外の場合はカウントダウンし、カウント値が設定された最大値になった場合に入光状態とし、カウント値が０となった場合に遮光状態とする（例えば、特許文献１参照）。 In a conventional photoelectric sensor, a light projection pulse from a light projector is received by a light receiver, converted into an electric signal, amplified, and output as a light reception signal. When this received light signal exceeds the threshold, a pulse is output from the comparator, and the up / down counter counts up each time the pulse is input, otherwise it counts down, and the count value reaches the set maximum value Is set to the light incident state, and when the count value becomes 0, the light is blocked (see, for example, Patent Document 1).

なお、チャタリング防止のため、コンパレータの実際の動作点は、閾値にヒステリシスの幅を加味して設定される。例えば反射形光電センサの場合、受光信号が大きい側から小さい側へ変化するとき（入光状態から遮光状態へ変化するとき、ＲＰ）と、受光信号が小さい側から大きい側へ変化するとき（遮光状態から入光状態へ変化するとき、ＯＰ）とで閾値が異なり、ＯＰ閾値はＲＰ閾値より高い。 In order to prevent chattering, the actual operating point of the comparator is set by adding a hysteresis width to the threshold value. For example, in the case of a reflection type photoelectric sensor, when the light reception signal changes from the large side to the small side (RP when changing from the light incident state to the light shielding state) and when the light reception signal changes from the small side to the large side (light shielding). When the state changes to the light incident state, the threshold value differs from OP), and the OP threshold value is higher than the RP threshold value.

特開２００４−２０７７７０号公報JP 2004-207770 A

受光量を電気信号に変換してコンパレータで閾値判定する構成の光電センサにおいては、受光量をデジタル値に変換しないので直接演算して最適な閾値を算出することができないという課題があった。そのため、閾値のオートチューニング（オートティーチング）は行われていなかった。 In the photoelectric sensor configured to convert the amount of received light into an electrical signal and determine the threshold value with a comparator, the amount of received light is not converted into a digital value, so that there has been a problem that the optimum threshold value cannot be calculated directly. Therefore, threshold auto-tuning (auto teaching) has not been performed.

他方、閾値を手動でチューニングする場合には、入光状態から遮光状態へ変化するときのＲＰ閾値のチューニングを行うのか、遮光状態から入光状態へ変化するときのＯＰ閾値のチューニングを行うのかによって閾値が異なるため、変化前の状態を光電センサに認識させる必要があった。
また、擬似的に入光／遮光状態を作り出し、アップダウンカウンタのカウントが終わるのを待つ必要があった。さらに、擬似的に入光／遮光するための回路も必要となる。 On the other hand, when manually tuning the threshold value, it depends on whether the RP threshold value is tuned when changing from the light incident state to the light shielding state, or the OP threshold value tuning when changing from the light shielding state to the light incident state. Since the threshold values are different, it is necessary to make the photoelectric sensor recognize the state before the change.
Further, it is necessary to create a light incident / light shielding state in a pseudo manner and wait for the up / down counter to finish counting. Furthermore, a circuit for artificially entering / blocking light is also required.

この発明は、上記のような課題を解決するためになされたもので、受光量を電気信号に変換してコンパレータで閾値判定する構成の光電センサにおいて、回路規模を増大することなく、素早くオートチューニングを実施することを目的とする。 The present invention has been made to solve the above-described problems. In a photoelectric sensor having a configuration in which a received light amount is converted into an electric signal and a threshold value is determined by a comparator, automatic tuning can be quickly performed without increasing the circuit scale. The purpose is to implement.

この発明に係る光電センサは、検出領域へ投光する投光素子と、投光素子からの光を受光し、受光量に応じたレベルの受光信号を出力する受光素子と、受光素子からの受光信号を所定の閾値で弁別して出力する弁別部と、弁別部の出力を所定の周期毎にカウントアップまたはカウントダウンするアップダウンカウンタと、アップダウンカウンタのカウント値が最大値のとき入光状態にあり、最小値のとき遮光状態にあることを示す信号を出力する出力制御部と、受光信号に基づいて弁別部の閾値をチューニングする場合に、アップダウンカウンタのカウント値を最大値または最小値にリセットする制御部とを備えるものである。 The photoelectric sensor according to the present invention includes a light projecting element that projects light to a detection region, a light receiving element that receives light from the light projecting element and outputs a light reception signal at a level corresponding to the amount of light received, and light reception from the light receiving element. Discriminating unit that discriminates and outputs signals with a predetermined threshold, up / down counter that counts up or down the output of the discriminating unit every predetermined period, and light entering state when the count value of the up / down counter is the maximum value When the threshold value of the discriminator is tuned based on the received light signal and the output control unit that outputs a signal indicating that the light is blocked at the minimum value, the count value of the up / down counter is reset to the maximum value or the minimum value. And a control unit.

この発明に係る光電センサは、検出領域へ投光する投光素子と、投光素子からの光を受光し、受光量に応じたレベルの受光信号を出力する受光素子と、受光素子からの受光信号を所定の閾値で弁別して出力する弁別部と、弁別部の出力を所定の周期毎にカウントアップまたはカウントダウンするアップダウンカウンタと、アップダウンカウンタのカウント値が最大値のとき入光状態にあり、最小値のとき遮光状態にあることを示す信号を出力する出力制御部と、受光信号と閾値との比較に基づいて増幅部の増幅度をチューニングする場合に、アップダウンカウンタのカウント値を最大値または最小値にリセットする制御部とを備えるものである。 The photoelectric sensor according to the present invention includes a light projecting element that projects light to a detection region, a light receiving element that receives light from the light projecting element and outputs a light reception signal at a level corresponding to the amount of light received, and light reception from the light receiving element. Discriminating unit that discriminates and outputs signals with a predetermined threshold, up / down counter that counts up or down the output of the discriminating unit every predetermined period, and light entering state when the count value of the up / down counter is the maximum value When the output control unit that outputs a signal indicating that the light is blocked at the minimum value and the amplification degree of the amplification unit are tuned based on the comparison between the received light signal and the threshold value, the count value of the up / down counter is maximized. And a controller that resets the value to the minimum value.

この発明に係る光電センサは、検出領域へ投光する投光素子と、投光素子からの光を受光し、受光量に応じたレベルの受光信号を出力する受光素子と、受光素子からの受光信号を所定の閾値で弁別して出力する弁別部と、弁別部の出力を所定の周期毎にカウントアップまたはカウントダウンするアップダウンカウンタと、アップダウンカウンタのカウント値が最大値のとき入光状態にあり、最小値のとき遮光状態にあることを示す信号を出力する出力制御部と、受光信号と閾値との比較に基づいて投光素子の投光量をチューニングする場合に、アップダウンカウンタのカウント値を最大値または最小値にリセットする制御部とを備えるものである。 The photoelectric sensor according to the present invention includes a light projecting element that projects light to a detection region, a light receiving element that receives light from the light projecting element and outputs a light reception signal at a level corresponding to the amount of light received, and light reception from the light receiving element. Discriminating unit that discriminates and outputs signals with a predetermined threshold, up / down counter that counts up or down the output of the discriminating unit every predetermined period, and light entering state when the count value of the up / down counter is the maximum value The output control unit that outputs a signal indicating that the light is blocked at the minimum value, and the count value of the up / down counter when tuning the light projection amount of the light projecting element based on the comparison between the light reception signal and the threshold value. And a control unit that resets to a maximum value or a minimum value.

この発明によれば、受光感度を調整する際にアップダウンカウンタのカウント値をリセットするようにしたので、アップダウンカウンタのカウントを待たずに入光状態または遮光状態を作り出すことができる。従って、受光量を電気信号に変換して弁別部で閾値判定する構成の光電センサにおいて、回路規模を増大することなく、素早くオートチューニングを実施することができる。 According to the present invention, since the count value of the up / down counter is reset when adjusting the light receiving sensitivity, it is possible to create a light incident state or a light shielding state without waiting for the count of the up / down counter. Therefore, in the photoelectric sensor having a configuration in which the received light amount is converted into an electric signal and the threshold value is determined by the discrimination unit, auto-tuning can be performed quickly without increasing the circuit scale.

この発明の実施の形態１に係る反射形光電センサの構成を示す回路図である。It is a circuit diagram which shows the structure of the reflection type photoelectric sensor which concerns on Embodiment 1 of this invention. 実施の形態１に係る反射形光電センサのアップダウンカウンタによるカウントアップ時の動作を説明する図である。It is a figure explaining the operation | movement at the time of count-up by the up / down counter of the reflection type photoelectric sensor which concerns on Embodiment 1. FIG. 実施の形態１に係る反射形光電センサのアップダウンカウンタによるカウントダウン時の動作を説明する図である。It is a figure explaining the operation | movement at the time of countdown by the up-down counter of the reflection type photoelectric sensor which concerns on Embodiment 1. FIG. 実施の形態１に係る反射形光電センサのアップダウンカウンタによるセットオン時の動作を説明する図である。It is a figure explaining the operation | movement at the time of set-on by the up-down counter of the reflection type photoelectric sensor which concerns on Embodiment 1. FIG. 実施の形態１に係る反射形光電センサのアップダウンカウンタによるセットオフ時の動作を説明する図である。It is a figure explaining the operation | movement at the time of the set-off by the up-down counter of the reflection type photoelectric sensor which concerns on Embodiment 1. FIG. 実施の形態１に係る反射形光電センサのオートチューニング動作を示すフローチャートであり、２分法の例である。It is a flowchart which shows the auto tuning operation | movement of the reflective photoelectric sensor which concerns on Embodiment 1, and is an example of a bisection method. 実施の形態１に係る反射形光電センサのオートチューニングを説明するグラフであり、２分法の例である。It is a graph explaining the auto-tuning of the reflective photoelectric sensor which concerns on Embodiment 1, and is an example of a bisection method. 実施の形態１に係る反射形光電センサのＯＰ閾値およびＲＰ閾値の概念図であり、逐次法によるオートチューニングの例である。It is a conceptual diagram of the OP threshold value and the RP threshold value of the reflective photoelectric sensor according to Embodiment 1, and is an example of auto-tuning by the sequential method.

実施の形態１．
図１は、この発明の実施の形態１に係る反射形光電センサ１の構成を示す回路図である。この反射形光電センサ１は、投光素子２（例えば、発光ダイオード）と、投光回路３と、受光素子４（例えば、フォトダイオード）と、増幅回路５と、コンパレータ（弁別部）６と、閾値設定回路７と、パルス検出回路８と、アップダウンカウンタ９と、出力制御回路１０と、制御部１１と、記憶部１２とから構成される。 Embodiment 1 FIG.
FIG. 1 is a circuit diagram showing a configuration of a reflective photoelectric sensor 1 according to Embodiment 1 of the present invention. The reflective photoelectric sensor 1 includes a light projecting element 2 (for example, a light emitting diode), a light projecting circuit 3, a light receiving element 4 (for example, a photodiode), an amplifier circuit 5, a comparator (discriminating unit) 6, The threshold setting circuit 7, the pulse detection circuit 8, the up / down counter 9, the output control circuit 10, the control unit 11, and the storage unit 12 are configured.

反射形の場合、投光素子２および投光回路３を一体化した投光器と、受光素子４、増幅回路５、コンパレータ６、閾値設定回路７、パルス検出回路８、アップダウンカウンタ９、出力制御回路１０、制御部１１および記憶部１２を一体化した受光器とを、検出対象物の存在する検出領域に対して同じ側に並べて設置し、投光器から発した光の検出対象物による反射光を受光器で受光することで、その受光量の変化から入光状態か遮光状態かを判定する。 In the case of the reflection type, a projector in which the light projecting element 2 and the light projecting circuit 3 are integrated, a light receiving element 4, an amplifier circuit 5, a comparator 6, a threshold setting circuit 7, a pulse detection circuit 8, an up / down counter 9, and an output control circuit 10. A light receiver in which the control unit 11 and the storage unit 12 are integrated is arranged side by side on the same side with respect to the detection region where the detection target exists, and light reflected from the detection target of the light emitted from the projector is received. When the light is received by the detector, it is determined from the change in the amount of received light whether the light is incident or light is blocked.

投光回路３は、投光素子２を駆動して、所定光量のパルスを検出領域へ投光させる。受光素子４は、検出領域からの反射光を受光して、受光量に応じた電気信号に変換して受光信号とする。増幅回路５は、この受光信号を増幅してコンパレータ６の一方の入力端子へ入力する。閾値設定回路７は、例えば、コンパレータ６のもう一方の入力端子に接続した可変抵抗器で構成され、アップダウンカウンタ９からオン信号が入力されるとＲＰ閾値を設定し、オン信号の入力が途絶えるとＯＰ閾値を設定する。コンパレータ６は、一方の入力端子に入力される増幅回路５の受光信号を、もう一方の入力端子に入力される閾値設定回路７の閾値（ＯＰまたはＲＰ）で弁別して出力する。反射形の場合、コンパレータ６は、値が小さい側から大きい側へ変化するときの受光信号をＯＰ閾値と比較して、受光信号がＯＰ閾値以上の場合に検出対象物が有る状態（入光状態）と判定し、パルス検出回路８へパルスを出力する。また、コンパレータ６は、値が大きい側から小さい側へ変化するときの受光信号をＲＰ閾値と比較して、受光信号がＲＰ閾値以下の場合に検出対象物が無い状態（遮光状態）と判定し、パルス検出回路８へパルスを出力しない。これらＯＰ，ＲＰ閾値は、後述するオートチューニングにより決定される。 The light projecting circuit 3 drives the light projecting element 2 to project a pulse having a predetermined light amount onto the detection area. The light receiving element 4 receives reflected light from the detection region and converts it into an electrical signal corresponding to the amount of received light to obtain a light receiving signal. The amplifier circuit 5 amplifies the received light signal and inputs it to one input terminal of the comparator 6. The threshold setting circuit 7 is composed of, for example, a variable resistor connected to the other input terminal of the comparator 6. When an on signal is input from the up / down counter 9, the threshold setting circuit 7 sets an RP threshold and the input of the on signal is interrupted. And set the OP threshold. The comparator 6 discriminates and outputs the light reception signal of the amplifier circuit 5 input to one input terminal by the threshold value (OP or RP) of the threshold setting circuit 7 input to the other input terminal. In the case of the reflection type, the comparator 6 compares the light reception signal when the value changes from the small side to the large side with the OP threshold value, and the detection target is present when the light reception signal is equal to or greater than the OP threshold value (light incident state). ) And outputs a pulse to the pulse detection circuit 8. The comparator 6 compares the light reception signal when the value changes from the larger side to the smaller side with the RP threshold value, and determines that there is no detection target (light shielding state) when the light reception signal is equal to or less than the RP threshold value. No pulse is output to the pulse detection circuit 8. These OP and RP threshold values are determined by auto-tuning described later.

反射形の場合、投光器側の投光回路３と受光器側のパルス検出回路８は同期信号に基づいて同期されており、パルス検出回路８は、コンパレータ６から入力されるパルスが投光素子２から投光された自発光に対応した有効なパルスか否かを同期信号を用いて判定し、有効なパルスをアップダウン信号としてアップダウンカウンタ９へ入力する。また、パルス検出回路８からアップダウンカウンタ９へ、同期信号に同期した周期的なカウントが入力される。 In the case of the reflection type, the light projecting circuit 3 on the light projector side and the pulse detecting circuit 8 on the light receiver side are synchronized based on the synchronization signal, and the pulse detecting circuit 8 receives the pulse input from the comparator 6 as the light projecting element 2. Whether or not the pulse is an effective pulse corresponding to the self-emitted light emitted from is determined using a synchronization signal, and the effective pulse is input to the up / down counter 9 as an up / down signal. A periodic count synchronized with the synchronization signal is input from the pulse detection circuit 8 to the up / down counter 9.

図２は、アップダウンカウンタ９のカウントアップ時の動作を示し、図３はカウントダウン時の動作を示す。図２および図３の各横軸は時間である。
アップダウンカウンタ９は、周期的なカウント毎に（図２（ａ）、図３（ａ））、アップダウン信号が入力された場合はカウントアップし（図２（ｃ））、パルスが入力されない場合はカウントダウンする（図３（ｃ））。そして、カウント値が最大値の５になると入光状態としてオン信号を出力し（図２（ｄ））、カウント値が最小値の０になると遮光状態としてオン信号出力を停止する（図３（ｄ））。出力制御回路１０は、アップダウンカウンタ９のオン信号の入力有無に応じて接点を開閉する。 FIG. 2 shows the operation when the up / down counter 9 is counting up, and FIG. 3 shows the operation when counting down. Each horizontal axis in FIGS. 2 and 3 represents time.
The up / down counter 9 counts up when an up / down signal is input at every periodic count (FIGS. 2A and 3A) (FIG. 2C), and no pulse is input. In this case, it counts down (FIG. 3C). When the count value reaches the maximum value of 5, an ON signal is output as the light incident state (FIG. 2D), and when the count value reaches the minimum value of 0, the ON signal output is stopped as the light shielding state (FIG. 3 ( d)). The output control circuit 10 opens and closes the contacts according to whether or not an ON signal is input to the up / down counter 9.

図４は、アップダウンカウンタ９のセットオン動作を示し、図５はセットオフ動作を示す。図４および図５の各横軸は時間である。
アップダウンカウンタ９は、制御部１１からセットオン信号が入力されると（図４（ｅ））、カウント値を最大値（例えば、５）に変更し（図４（ｃ））、オン信号を出力する（図４（ｄ））。一方、制御部１１からセットオフ信号が入力されると（図５（ｅ））、アップダウンカウンタ９はカウント値を最小値の０に変更し（図５（ｃ））、オン信号出力を停止する（図５（ｄ））。 FIG. 4 shows the set-on operation of the up / down counter 9, and FIG. 5 shows the set-off operation. Each horizontal axis in FIGS. 4 and 5 represents time.
When the set-on signal is input from the control unit 11 (FIG. 4E), the up / down counter 9 changes the count value to the maximum value (for example, 5) (FIG. 4C), Output (FIG. 4D). On the other hand, when a set-off signal is input from the control unit 11 (FIG. 5 (e)), the up / down counter 9 changes the count value to the minimum value 0 (FIG. 5 (c)) and stops the on signal output. (FIG. 5D).

セットオン信号またはセットオフ信号をアップダウンカウンタ９に与えてカウント値をリセットする場合、即座にカウント値をリセットでき、疑似的な入光状態または遮光状態を作り出すことができる。一方、このようなリセット機能が無い場合、現在のカウント値を０または最大値へ１カウントずつ遷移させる必要があるため、擬似的な入光状態または遮光状態を作り出すために最大５カウント分の時間を有する。 When the count value is reset by supplying a set-on signal or a set-off signal to the up / down counter 9, the count value can be reset immediately, and a pseudo light incident state or light shielding state can be created. On the other hand, when there is no such reset function, it is necessary to shift the current count value to 0 or 1 count at a time, so that a time corresponding to a maximum of 5 counts is required to create a pseudo light incident state or light shielding state. Have

以上の投光素子２、投光回路３、受光素子４、増幅回路５、コンパレータ６、閾値設定回路７、パルス検出回路８、アップダウンカウンタ９および出力制御回路１０は、アナログ回路で構成する。一方、以下に説明する制御部１１はアナログ回路で構成してもよいし、マイクロコンピュータ等のデジタル回路で構成してもよい。また、記憶部１２は、ＥＥＰＲＯＭ（ＥｌｅｃｔｒｉｃａｌｌｙＥｒａｓａｂｌｅＰｒｏｇｒａｍｍａｂｌｅＲｅａｄ−ＯｎｌｙＭｅｍｏｒｙ）等の記憶素子で構成する。 The light projecting element 2, the light projecting circuit 3, the light receiving element 4, the amplifying circuit 5, the comparator 6, the threshold setting circuit 7, the pulse detecting circuit 8, the up / down counter 9, and the output control circuit 10 are configured by analog circuits. On the other hand, the control unit 11 described below may be configured with an analog circuit or a digital circuit such as a microcomputer. The storage unit 12 includes a storage element such as an EEPROM (Electrically Erasable Programmable Read-Only Memory).

記憶部１２は、反射形光電センサ１の各種の設定情報（例えば、カウントアップの最大値）を記憶しており、制御部１１がその情報を読み出して、アップダウンカウンタ９にカウント段数制御信号を出力することによりカウントアップの最大値を設定する。また、制御部１１は、記憶部１２に記憶されているオートチューニングのプログラムを読み出して実行し、アップダウンカウンタ９の出力するオン信号を利用して求めたＯＰ閾値とＲＰ閾値を閾値レベル選択信号として閾値設定回路７に出力することにより、反射形光電センサ１の受光感度を調整する。また、オートチューニング中に、必要に応じて制御部１１からアップダウンカウンタ９へセットオン信号およびセットオフ信号を出力して、アップダウンカウンタ９のカウント値を最大値（例えば、５）または最小値（０）に強制的に移行させることにより、素早く擬似的な入光状態または遮光状態を作り出す。 The storage unit 12 stores various setting information (for example, the maximum count-up value) of the reflective photoelectric sensor 1, and the control unit 11 reads the information and sends a count stage number control signal to the up / down counter 9. The maximum count-up value is set by outputting. Further, the control unit 11 reads and executes the auto tuning program stored in the storage unit 12, and sets the OP threshold value and the RP threshold value obtained by using the ON signal output from the up / down counter 9 as the threshold level selection signal. Is output to the threshold value setting circuit 7 to adjust the light receiving sensitivity of the reflective photoelectric sensor 1. Further, during auto tuning, a set-on signal and a set-off signal are output from the control unit 11 to the up / down counter 9 as necessary, and the count value of the up / down counter 9 is set to a maximum value (for example, 5) or a minimum value. By forcibly shifting to (0), a pseudo light incident state or light blocking state is quickly created.

以下、反射形光電センサ１のオートチューニングを説明する。図６は、２分法によるＯＰ閾値を求めるフローチャートであり、フローチャートに沿った動作例を、図７のグラフを参照しながら説明する。グラフの縦軸は受光信号の光量、横軸はフローのループ回数である。オートチューニングを実施する場合、検出領域に検出対象物体が存在する入光状態を保ち、このときの入光量からＯＰ閾値およびＲＰ閾値を推定する。 Hereinafter, auto-tuning of the reflective photoelectric sensor 1 will be described. FIG. 6 is a flowchart for obtaining the OP threshold by the bisection method, and an operation example according to the flowchart will be described with reference to the graph of FIG. The vertical axis of the graph represents the light amount of the received light signal, and the horizontal axis represents the flow loop count. When performing auto-tuning, the light incident state where the detection target object exists in the detection region is maintained, and the OP threshold value and the RP threshold value are estimated from the light incident amount at this time.

制御部１１は、記憶部１２に記憶されている設定情報のうち、ループ回数ｉ＝Ｎ（例えば、ｉ＝８とする）を設定すると共に（ステップＳＴ１）、閾値が取り得る範囲の最大値を閾値上限に、最小値を閾値下限に初期設定する（ステップＳＴ２）。続いて制御部１１は、閾値上限から閾値下限の範囲を２分する中間値を仮のＯＰ閾値に設定し（ステップＳＴ３）、セットオフ信号を出力してアップダウンカウンタ９のカウント値を０にし、遮光状態とする（ステップＳＴ４）。図７において、閾値上限を三角形（△）、閾値下限を四角形（□）、仮のＯＰ閾値を白丸（○）、入光量を破線で表す。 The control unit 11 sets the loop count i = N (for example, i = 8) among the setting information stored in the storage unit 12 (step ST1), and sets the maximum value that the threshold can take. The minimum value is initially set as the threshold lower limit as the threshold upper limit (step ST2). Subsequently, the control unit 11 sets an intermediate value that bisects the range from the upper threshold to the lower threshold as a temporary OP threshold (step ST3), outputs a set-off signal, and sets the count value of the up / down counter 9 to zero. Then, a light shielding state is set (step ST4). In FIG. 7, the threshold upper limit is represented by a triangle (Δ), the threshold lower limit is represented by a square (□), the provisional OP threshold is represented by a white circle (◯), and the incident light amount is represented by a broken line.

続いて入光状態を判定する（ステップＳＴ５）。先ず、制御部１１から仮のＯＰ閾値が通知された閾値設定回路７が、コンパレータ６に仮のＯＰ閾値を設定する。コンパレータ６は受光信号（図７に破線で示す入光量）が仮のＯＰ閾値以上の場合にアップダウン信号を出力し、アップダウンカウンタ９がカウント値を０から最大値までカウントアップしていき、入光状態を表すオン信号を出力する（ステップＳＴ５“ＯＮ”）。すると、制御部１１がこのオン信号を受けて、図７のｉ＝８のときのように閾値下限を仮のＯＰ閾値に変更する（ステップＳＴ６）。 Subsequently, the light incident state is determined (step ST5). First, the threshold setting circuit 7 notified of the temporary OP threshold from the control unit 11 sets the temporary OP threshold in the comparator 6. The comparator 6 outputs an up / down signal when the received light signal (incident light amount indicated by a broken line in FIG. 7) is equal to or larger than the temporary OP threshold, and the up / down counter 9 counts up the count value from 0 to the maximum value. An ON signal indicating the incident light state is output (step ST5 “ON”). Then, the control unit 11 receives this ON signal, and changes the threshold lower limit to a temporary OP threshold as in the case of i = 8 in FIG. 7 (step ST6).

一方、受光信号が仮のＯＰ閾値より小さい場合は、コンパレータ６からアップダウン信号が出力されず、例えばカウント５回分の時間が経過してもアップダウンカウンタ９のカウント値が０のままであってオン信号が出力されない。この場合、制御部１１は、セットオフ信号を出力して擬似的に遮光状態を作り出した後、例えばカウント５回分の時間が経過してもオン信号が入力されなければ（ステップＳＴ５“ＯＦＦ”）、遮光状態が継続していると判断して、図７のｉ＝７のときのように閾値上限を仮のＯＰ閾値に変更する（ステップＳＴ７）。 On the other hand, when the received light signal is smaller than the temporary OP threshold value, the up / down signal is not output from the comparator 6, and the count value of the up / down counter 9 remains 0 even when, for example, 5 counts have elapsed. No ON signal is output. In this case, after outputting the set-off signal and creating a pseudo light-shielding state, the control unit 11 does not receive an ON signal even if, for example, a time of 5 counts has elapsed (step ST5 “OFF”). Then, it is determined that the light shielding state continues, and the upper limit threshold is changed to a temporary OP threshold as in the case of i = 7 in FIG. 7 (step ST7).

制御部１１は、閾値上限または閾値下限を仮のＯＰ閾値に変更した後ループ回数ｉをデクリメントし（ステップＳＴ８）、ｉ＝０になればオートチューニングを終了して（ステップＳＴ９“ＹＥＳ”）、そのときの仮のＯＰ閾値を正式なＯＰ閾値として閾値設定回路７へ通知する。 The controller 11 decrements the loop count i after changing the threshold upper limit or threshold lower limit to the temporary OP threshold (step ST8), and ends auto-tuning when i = 0 (step ST9 “YES”). The temporary OP threshold at that time is notified to the threshold setting circuit 7 as a formal OP threshold.

ｉ=０でなければ（ステップＳＴ９“ＮＯ”）、再びステップＳＴ３へ戻り、変更後の閾値上限から閾値下限の範囲を２分する中間値を仮のＯＰ閾値に設定して入光状態を判定する処理を繰り返す。この処理を繰り返すことにより、仮のＯＰ閾値を入光量に近づけていくことができ、受光感度を調整できる。 If i = 0 is not satisfied (“NO” in step ST9), the process returns to step ST3 again, and an intermediate value that divides the range between the upper limit of the threshold value and the lower limit of the threshold value into two is set as a temporary OP threshold to determine the light incident state Repeat the process. By repeating this process, the temporary OP threshold can be made closer to the incident light amount, and the light receiving sensitivity can be adjusted.

上記説明では、遮光状態から入光状態への変化を検出するためのＯＰ閾値をオートチューニングしたが、同様の方法で、入光状態から遮光状態への変化を検出するためのＲＰ閾値もオートチューニングする。ＲＰ閾値をオートチューニングする場合、制御部１１は、ステップＳＴ３において仮のＯＰ閾値からヒステリシスの幅を加味して仮のＲＰ閾値（図７に黒丸（●）で示す）を設定する。また、制御部１１は、ステップＳＴ４においてセットオン信号を出力してアップダウンカウンタ９のカウント値を最大値にし、擬似的な入光状態を作り出して仮のＲＰ閾値に基づく判定を行う。 In the above description, the OP threshold value for detecting the change from the light-blocking state to the light-blocking state is auto-tuned. However, the RP threshold value for detecting the change from the light-blocking state to the light-blocking state is also auto-tuned by the same method. To do. When auto-tuning the RP threshold value, the control unit 11 sets a temporary RP threshold value (indicated by a black circle (●) in FIG. 7) in consideration of the hysteresis width from the temporary OP threshold value in step ST3. Further, in step ST4, the control unit 11 outputs a set-on signal, maximizes the count value of the up / down counter 9, creates a pseudo light incident state, and makes a determination based on the temporary RP threshold value.

なお、ＯＰ閾値およびＲＰ閾値の探索方法は、図６に示す２分法に限定されるものではなく、任意の方法でよい。以下に、図８を参照しながら逐次法を説明する。
図８は、ＯＰ閾値およびＲＰ閾値の概念図であり、縦軸を光量とする。前の状態とは、セットオン信号出力時の擬似的な入光状態、またはセットオフ信号出力時の擬似的な遮光状態のことであり、後の状態とは、入光状態の判定結果のことである。前の状態がＯＦＦ（遮光状態）の場合、後の状態がＯＦＦであれば光量＜ＯＰ閾値、後の状態がＯＮ（入光状態）であれば光量＞ＯＰ閾値となる。一方、前の状態がＯＮの場合、後の状態がＯＦＦであれば光量＜ＲＰ閾値、後の状態がＯＮであれば光量＞ＲＰ閾値となる。 Note that the search method for the OP threshold value and the RP threshold value is not limited to the bisection method shown in FIG. 6, and may be any method. Hereinafter, the sequential method will be described with reference to FIG.
FIG. 8 is a conceptual diagram of the OP threshold and the RP threshold, and the vertical axis represents the light amount. The previous state is a pseudo light incident state when a set-on signal is output or a pseudo light-shielding state when a set-off signal is output, and the subsequent state is a determination result of the light incident state. It is. When the previous state is OFF (light shielding state), the light amount <OP threshold value if the subsequent state is OFF, and the light amount> OP threshold value if the subsequent state is ON (light incident state). On the other hand, if the previous state is ON, the light amount <RP threshold value if the subsequent state is OFF, and the light amount> RP threshold value if the subsequent state is ON.

制御部１１は、仮のＲＰ閾値と仮のＯＰ閾値を閾値下限側から徐々に閾値上限側に変更しながら、入光状態か否か繰り返し判定していき、図８に示すように後の状態がＯＦＦからＯＮになる境界のＲＰ閾値と、後の状態がＯＦＦからＯＮになる境界のＯＰ閾値を探す。もちろん、仮のＲＰ閾値と仮のＯＰ閾値を閾値上限側から徐々に閾値下限側に変更してもよい。また、仮のＲＰ閾値と仮のＯＰ閾値を設定する際にヒステリシスの幅を加味する必要がある。 The control unit 11 repeatedly determines whether or not the light is in an incident state while gradually changing the temporary RP threshold and the temporary OP threshold from the threshold lower limit side to the threshold upper limit side, as shown in FIG. Search for the RP threshold value at the boundary where A is turned from OFF to ON and the OP threshold value at the boundary where the subsequent state is turned from OFF to ON. Of course, the temporary RP threshold and the temporary OP threshold may be gradually changed from the threshold upper limit side to the threshold lower limit side. Moreover, it is necessary to consider the hysteresis width when setting the temporary RP threshold and the temporary OP threshold.

以上より、実施の形態１によれば、反射形光電センサ１は、検出領域へ投光する投光素子２と、投光素子２からの光を受光し、受光量に応じたレベルの受光信号を出力する受光素子４と、受光素子４からの受光信号を所定の閾値（ＯＰまたはＲＰ）で弁別して出力するコンパレータ６と、コンパレータ６の出力を所定の周期毎にカウントアップまたはカウントダウンするアップダウンカウンタ９と、アップダウンカウンタ９のカウント値が最大値のとき入光状態にあり、最小値のとき遮光状態にあることを示す信号を出力する出力制御回路１０と、受光信号に基づいてコンパレータ６の閾値をチューニングする場合に、アップダウンカウンタ９のカウント値を最大値または最小値にリセットする制御部１１とを備えるように構成した。このため、コンパレータ６の閾値をチューニングする際に、制御部１１からセットオン信号またはセットオフ信号を出力することにより、アップダウンカウンタ９のカウント値が最大値または最小値になるのを待たずに入光状態または遮光状態を作り出すことができる。従って、受光量を電気信号に変換してコンパレータ６で閾値判定する構成の反射形光電センサ１において、回路規模を増大することなく、素早くオートチューニングを実施することができる。 As described above, according to the first embodiment, the reflective photoelectric sensor 1 receives the light from the light projecting element 2 that projects light onto the detection region and the light from the light projecting element 2, and receives light at a level corresponding to the amount of light received. , A comparator 6 that discriminates and outputs a light-receiving signal from the light-receiving element 4 with a predetermined threshold (OP or RP), and an up-down that counts up or down the output of the comparator 6 at predetermined intervals The counter 9, the output control circuit 10 that outputs a signal indicating that the light is in the incident state when the count value of the up / down counter 9 is the maximum value, and the light shielding state when the value is the minimum value, and the comparator 6 based on the light reception signal The control unit 11 is configured to reset the count value of the up / down counter 9 to the maximum value or the minimum value when tuning the threshold value. For this reason, when tuning the threshold value of the comparator 6, a set-on signal or a set-off signal is output from the control unit 11 without waiting for the count value of the up / down counter 9 to reach the maximum value or the minimum value. A light incident state or a light shielding state can be created. Therefore, in the reflective photoelectric sensor 1 having a configuration in which the received light amount is converted into an electric signal and the threshold value is determined by the comparator 6, auto-tuning can be performed quickly without increasing the circuit scale.

また、実施の形態１によれば、制御部１１は、アップダウンカウンタ９の閾値が取り得る範囲の最大値を閾値上限、最小値を閾値下限に初期設定し、閾値上限および閾値下限から仮の閾値を求めて閾値設定回路７を介してコンパレータ６に設定して入光状態か遮光状態かを判定し、入光状態であった場合は当該仮の閾値を閾値下限に設定する一方、遮光状態であった場合は当該仮の閾値を閾値上限に設定して当該仮の閾値を求め直すことを繰り返し、所定回数繰り返した後の仮の閾値をコンパレータ６に設定するように構成した。このため、受光量を電気信号に変換してコンパレータ６で閾値判定する構成の反射形光電センサ１において、受光量に基づいてＯＰ閾値およびＲＰ閾値のオートチューニングを実施することができ、ＯＰ閾値のチューニングを行うのかＲＰ閾値のチューニングを行うのか外部から設定する必要がない。また、２分法を利用して素早く閾値を探索することができ、チューニング時間を短縮することができる。 Further, according to the first embodiment, the control unit 11 initially sets the maximum value of the range that can be taken by the threshold value of the up / down counter 9 as the threshold upper limit and the minimum value as the threshold lower limit. The threshold value is obtained and set in the comparator 6 via the threshold setting circuit 7 to determine whether the light is in the light incident state or the light shielding state. If it is in the light incident state, the temporary threshold is set as the threshold lower limit. In this case, the provisional threshold is set to the upper limit threshold and the provisional threshold is obtained again, and the provisional threshold after being repeated a predetermined number of times is set in the comparator 6. Therefore, in the reflective photoelectric sensor 1 configured to convert the received light amount into an electrical signal and determine the threshold value by the comparator 6, the OP threshold value and the RP threshold value can be automatically tuned based on the received light amount. There is no need to externally set whether to perform tuning or tuning of the RP threshold. Further, the threshold value can be quickly searched using the bisection method, and the tuning time can be shortened.

なお、以上の説明ではオートチューニング（自動で感度調整）する場合に自動的にセットオン信号およびセットオフ信号を出力する構成にしたが、マニュアルチューニング（手動で感度調整）する場合に、ボタン操作などによる外部からの指示を受け付けてセットオン信号およびセットオフ信号を出力する構成にしてもよい。 In the above description, the set-on signal and set-off signal are automatically output when auto-tuning (automatic sensitivity adjustment). However, when manual tuning (manual sensitivity adjustment) is performed, button operation, etc. A configuration may be adopted in which a set-on signal and a set-off signal are output in response to an instruction from the outside.

また、以上の説明では、反射形光電センサ１の感度調整として、受光量の閾値（ＯＰおよびＲＰ）をチューニングしたが、閾値に限定されるものではない。例えば、閾値は固定して、増幅回路５の増幅度（ゲイン）を変更しながら入光状態の判定を繰り返すことにより増幅度をチューニングしたり、投光素子２からの投光量を変更しながら入光状態の判定を繰り返すことにより投光量をチューニングしたりして、反射形光電センサ１の感度調整を行ってもよい。増幅度の調整は、制御部１１から増幅回路５へ増幅度選択信号を通知することにより行い、投光量の調整は、制御部１１から投光回路３へ投光量選択信号を通知することにより行えばよい。 In the above description, the threshold values (OP and RP) of the received light amount are tuned as sensitivity adjustment of the reflective photoelectric sensor 1, but the present invention is not limited to the threshold values. For example, the threshold value is fixed, and the amplification degree is tuned by repeating the determination of the incident light state while changing the amplification degree (gain) of the amplifier circuit 5 or the incident light quantity from the light projecting element 2 is changed. The sensitivity of the reflective photoelectric sensor 1 may be adjusted by tuning the light projection amount by repeating the determination of the light state. The adjustment of the amplification degree is performed by notifying the amplification degree selection signal from the control unit 11 to the amplification circuit 5, and the adjustment of the light emission amount is performed by notifying the light emission amount selection signal from the control unit 11 to the light projection circuit 3. Just do it.

さらに、閾値、増幅度および投光量のうちの複数を変更することにより受光感度を調整してもよい。例えば、増幅度（２段階）と閾値を両方変更する場合、制御部１１は、先ず２段階の増幅度のどちらのときにオン信号が出力されるか入光状態を判定し、オン信号が出力される増幅度に設定した状態で図６のフローチャートを実行して閾値をチューニングする。 Furthermore, the light receiving sensitivity may be adjusted by changing a plurality of threshold values, amplification factors, and light projection amounts. For example, when both the amplification degree (two stages) and the threshold value are changed, the control unit 11 first determines the light incident state when the amplification signal is output in two stages, and the on signal is output. The threshold value is tuned by executing the flowchart of FIG.

また、以上の説明では、反射形光電センサ１のチューニングを行ったが、このチューニングを透過形の光電センサに適用することも可能である。透過形の光電センサは、検出領域を間に挟んで投光器と受光器を向かい合わせに設置し、検出領域に検出対象物が存在するとき投光器から発せられた光が検出対象物に遮蔽されることを利用して物体検出を行う。従って、検出領域に検出対象物が有ると受光信号が小さく、検出対象物が無いと受光信号が大きくなる点が反射形光電センサ１とは異なるのみで、反射形光電センサ１と同様の方法によりチューニングを行うことができ、反射形光電センサ１を透過形としても使用可能である。 In the above description, the reflective photoelectric sensor 1 is tuned. However, this tuning can also be applied to a transmissive photoelectric sensor. A transmissive photoelectric sensor has a projector and a light receiver placed facing each other with a detection region in between, and when the detection target exists in the detection region, the light emitted from the projector is shielded by the detection target Detect objects using. Therefore, the light receiving signal is small when there is a detection target in the detection region, and the light receiving signal is large when there is no detection target, except that it is different from the reflective photoelectric sensor 1 in the same manner as the reflective photoelectric sensor 1. Tuning can be performed, and the reflective photoelectric sensor 1 can also be used as a transmission type.

ただし、透過形の場合、投光器と受光器を離間して設置するので、同期信号用の信号線を配策しにくい。そのため、透過形として使用する場合には、パルス検出回路８が同期信号を用いずにコンパレータ６のパルスが有効か否かを判断する。従って、反射形光電センサ１を反射形および透過形として兼用可能に構成する場合には、パルス検出回路８のパルス検出方式を反射形と透過形とで切り替えるための検出方式信号を、制御部１１からパルス検出回路８へ出力し、パルス検出回路８は反射形のときは同期信号を用いてパルスの有効性を判断し、透過形のときは同期信号を用いない方法でパルスの有効性を判断する。 However, in the case of the transmissive type, the projector and the light receiver are installed apart from each other, so that it is difficult to route the signal line for the synchronization signal. Therefore, when used as a transmission type, the pulse detection circuit 8 determines whether the pulse of the comparator 6 is valid without using the synchronization signal. Accordingly, when the reflection type photoelectric sensor 1 is configured to be used as both a reflection type and a transmission type, a detection method signal for switching the pulse detection method of the pulse detection circuit 8 between the reflection type and the transmission type is supplied to the control unit 11. To the pulse detection circuit 8, the pulse detection circuit 8 determines the validity of the pulse by using the synchronization signal when the reflection type is used, and determines the validity of the pulse by a method that does not use the synchronization signal when the transmission type is the transmission type. To do.

ここまで本発明の実施形態を図面を参照して詳述してきたが、具体的な構成は、上述した実施の形態の構成に限られるものではなく、本発明の要旨を逸脱しない範囲の設計の変更などがあっても本発明に含まれることは言うまでもない。 The embodiment of the present invention has been described in detail with reference to the drawings, but the specific configuration is not limited to the configuration of the above-described embodiment, and the design is within the scope not departing from the gist of the present invention. Needless to say, changes and the like are included in the present invention.

１反射形光電センサ
２投光素子
３投光回路
４受光素子
５増幅回路
６コンパレータ（弁別部）
７閾値設定回路
８パルス検出回路
９アップダウンカウンタ
１０出力制御回路
１１制御部
１２記憶部 DESCRIPTION OF SYMBOLS 1 Reflection type photoelectric sensor 2 Light emitting element 3 Light emitting circuit 4 Light receiving element 5 Amplifying circuit 6 Comparator (discrimination part)
7 Threshold Setting Circuit 8 Pulse Detection Circuit 9 Up / Down Counter 10 Output Control Circuit 11 Control Unit 12 Storage Unit

Claims

A light projecting element that projects light to the detection area;
A light receiving element that receives light from the light projecting element and outputs a light receiving signal at a level corresponding to the amount of light received;
A discrimination unit that discriminates and outputs a light reception signal from the light receiving element at a predetermined threshold;
An up / down counter that counts up or counts down the output of the discriminator at predetermined intervals;
An output control unit that outputs a signal indicating that the up / down counter is in a light incident state when the count value is a maximum value and is in a light shielding state when the count value is a minimum value;
A photoelectric sensor comprising: a control unit that resets the count value of the up / down counter to a maximum value or a minimum value when tuning the threshold value of the discrimination unit based on the light reception signal.

The control unit initially sets a maximum value of a range that can be taken by the threshold value of the discrimination unit as a threshold upper limit and a minimum value as a threshold lower limit, and obtains a temporary threshold from the threshold upper limit and the threshold lower limit and sets the threshold in the discrimination unit In the case of the light incident state, the temporary threshold value is set to the lower threshold value. On the other hand, in the light blocked state, the temporary threshold value is set to the upper threshold value. 2. The photoelectric sensor according to claim 1, wherein setting and recalculating the temporary threshold are repeated, and the temporary threshold after being repeated a predetermined number of times is used as the threshold of the discrimination unit.

An amplification unit that amplifies a light reception signal from the light receiving element and inputs the amplified signal to the discrimination unit;
The control unit resets the count value of the up / down counter to a maximum value or a minimum value when tuning the amplification degree of the amplification unit based on a comparison between the light reception signal and a threshold value of the discrimination unit. The photoelectric sensor according to claim 1 or 2, wherein the photoelectric sensor is characterized in that:

The said control part resets the count value of the said up / down counter to the maximum value or the minimum value, when an instruction | indication is received from the outside, The any one of Claims 1-3 characterized by the above-mentioned. Photoelectric sensor.

A light projecting element that projects light to the detection area;
A light receiving element that receives light from the light projecting element and outputs a light receiving signal at a level corresponding to the amount of light received;
A discrimination unit that discriminates and outputs a light reception signal from the light receiving element at a predetermined threshold;
An up / down counter that counts up or counts down the output of the discriminator at predetermined intervals;
An output control unit that outputs a signal indicating that the count value of the up / down counter is in an input state when the count value is a maximum value and is in a light shielding state when the count value is a minimum value;
A photoelectric sensor comprising: a control unit that resets the count value of the up / down counter to a maximum value or a minimum value when tuning the amplification degree of the amplification unit based on a comparison between the light reception signal and the threshold value.

The said control part resets the count value of the said up / down counter to the maximum value or the minimum value, when tuning the threshold value of the said discrimination part based on the light reception signal of the said light receiving element. Photoelectric sensor.

The control unit sets the count value of the up / down counter to a maximum value or a minimum value when tuning the light projection amount of the light projection element based on a comparison between a light reception signal of the light reception element and a threshold value of the discrimination unit. 7. The photoelectric sensor according to claim 5, wherein the photoelectric sensor is reset.

The control unit initially sets a maximum value of a range that can be taken by the threshold value of the discrimination unit as a threshold upper limit and a minimum value as a threshold lower limit, and obtains a temporary threshold from the threshold upper limit and the threshold lower limit and sets the threshold in the discrimination unit In the case of the light incident state, the temporary threshold value is set to the lower threshold value. On the other hand, in the light blocked state, the temporary threshold value is set to the upper threshold value. 7. The photoelectric sensor according to claim 6, wherein setting and re-determining the temporary threshold are repeated, and the temporary threshold after being repeated a predetermined number of times is used as the threshold of the discrimination unit.

The said control part resets the count value of the said up / down counter to the maximum value or the minimum value, when an instruction | indication is received from the outside, Any one of Claims 5-8 characterized by the above-mentioned. Photoelectric sensor.

A light projecting element that projects light to the detection area;
A light receiving element that receives light from the light projecting element and outputs a light receiving signal at a level corresponding to the amount of light received;
A discrimination unit that discriminates and outputs a light reception signal from the light receiving element at a predetermined threshold;
An up / down counter that counts up or counts down the output of the discriminator at predetermined intervals;
An output control unit that outputs a signal indicating that the up / down counter is in a light incident state when the count value is a maximum value and is in a light shielding state when the count value is a minimum value;
A photoelectric sensor comprising: a control unit that resets the count value of the up / down counter to a maximum value or a minimum value when tuning a light projection amount of the light projecting element based on a comparison between the light reception signal and the threshold value.

An amplification unit that amplifies a light reception signal from the light receiving element and inputs the amplified signal to the discrimination unit;
The control unit resets the count value of the up / down counter to a maximum value or a minimum value when tuning the amplification degree of the amplification unit based on a comparison between the light reception signal and a threshold value of the discrimination unit. The photoelectric sensor according to claim 10.

12. The photoelectric sensor according to claim 10, wherein the controller resets the count value of the up / down counter to a maximum value or a minimum value when receiving an instruction from the outside.