JP2020148642A

JP2020148642A - Optical sensor

Info

Publication number: JP2020148642A
Application number: JP2019046743A
Authority: JP
Inventors: 信太郎安藤; Shintaro Ando; 公輔植村; Kosuke Uemura
Original assignee: Omron Corp; Omron Tateisi Electronics Co
Current assignee: Omron Corp
Priority date: 2019-03-14
Filing date: 2019-03-14
Publication date: 2020-09-17
Anticipated expiration: 2039-03-14
Also published as: JP7037770B2

Abstract

To provide an optical sensor that can detect a signal noise even in a case where the optical sensor has a short exposure time compared with the period of the signal noise including pulse disturbance light.SOLUTION: An optical sensor comprises: a light projection unit 10 that projects light on a detection area; a light receiving unit 20 that receives light from the detection area and outputs light reception signals indicating the quantity of received light; a comparison unit 31 that compares the level of a first light reception signal at a first timing with the level of a second light reception signal at a second timing; and an output unit 32 that outputs candidates for a signal noise in the light reception signals based on a result of comparison performed by the comparison unit.SELECTED DRAWING: Figure 1

Description

本発明は、光電センサに関する。 The present invention relates to a photoelectric sensor.

従来、検出対象物に光を投光し、検出対象物から反射した光を受光する光学式センサでは、外乱光による信号ノイズを検出して、当該信号ノイズの影響を低減するよう投光のサイクルを調整することがある。また、このような外乱光には、ＬＥＤ照明等から発せられるパルス点灯する外乱光（以下、「パルス外乱光」という）が含まれる場合がある。下記特許文献１には、パルス間隔が互いに異なる第１パルス間隔と第２パルス間隔とを有するパルス光の組を信号光として繰り返し発する投光素子を有し、受光信号データから第１パルス間隔と第２パルス間隔とを有するパルス光の組を探して入光状態又は遮光状態を判断して投光素子からの信号光を識別することができる、パルス外乱光に対する耐性を向上させるための光学センサが開示されている。 Conventionally, an optical sensor that projects light onto a detection target and receives the light reflected from the detection target detects signal noise due to ambient light and reduces the effect of the signal noise in the light projection cycle. May be adjusted. Further, such disturbance light may include disturbance light (hereinafter, referred to as “pulse disturbance light”) that is pulse-lit and emitted from LED lighting or the like. The following Patent Document 1 has a light projecting element that repeatedly emits a set of pulsed light having a first pulse interval and a second pulse interval having different pulse intervals as signal light, and obtains the first pulse interval from the received signal data. An optical sensor for improving resistance to pulse disturbance light, which can identify a signal light from a light projecting element by searching for a set of pulsed light having a second pulse interval and determining an incoming light state or a light blocking state. Is disclosed.

また、従来の光学式センサにおいては、図５の（ａ）従来のセンサＡの露光時間及び（ｂ）従来のセンサＢの露光時間に示すように、パルス外乱光の点灯周期と比較して光学式センサの露光時間が十分に長く、当該露光時間の間に複数パルス分が蓄積されて受光信号全体のレベルが上がるため、受光波形のピーク値の検出等において受光信号に対するパルス外乱光の影響は受けにくかった。なお、露光時間とは、光学式センサの受光期間の長さとしてもよいし、投光期間と受光期間とが異なる場合には、両期間が重複する期間としてもよい。 Further, in the conventional optical sensor, as shown in (a) the exposure time of the conventional sensor A and (b) the exposure time of the conventional sensor B in FIG. 5, the optical is compared with the lighting cycle of the pulse disturbance light. Since the exposure time of the type sensor is sufficiently long and multiple pulses are accumulated during the exposure time and the level of the entire received light signal rises, the influence of pulse disturbance light on the received signal is affected in the detection of the peak value of the received light waveform. It was hard to receive. The exposure time may be the length of the light receiving period of the optical sensor, or may be a period in which both periods overlap when the light projecting period and the light receiving period are different.

特開２０１５−２１２７１１号公報Japanese Unexamined Patent Publication No. 2015-212711

近年、ＣＭＯＳセンサ素子又はＣＣＤセンサ素子等の撮像素子を使用した光学式センサにおいて、露光時間を長くすることで外乱光が多く蓄積されてしまい、受光素子が飽和しやすくなるという問題がある。そこで、光学式センサの露光時間を短くして、その分投光量を増やすことでＳ／Ｎ比を向上させる高速動作の光学式センサが存在する。しかしながら、このような高速動作の光学式センサにおいて、図５の（ｃ）高速動作のセンサＣ及び（ｄ）高速動作のセンサＤに示すように、パルス外乱光の点灯周期と比較して光学式センサの露光時間が短くなってしまうことがある。これにより、上記のような高速動作の光学式センサにおいては、露光時間の間にパルス外乱光の１パルスが蓄積されたりされなかったりと受光信号のレベルが大きく変化し、受光信号に対するパルス外乱光の影響は受けやすくなるという課題があった。 In recent years, in an optical sensor using an image pickup element such as a CMOS sensor element or a CCD sensor element, there is a problem that a large amount of ambient light is accumulated by lengthening the exposure time, and the light receiving element tends to be saturated. Therefore, there is a high-speed operation optical sensor that improves the S / N ratio by shortening the exposure time of the optical sensor and increasing the amount of light projected accordingly. However, in such a high-speed operation optical sensor, as shown in (c) high-speed operation sensor C and (d) high-speed operation sensor D in FIG. 5, the optical type is compared with the lighting cycle of the pulse disturbance light. The exposure time of the sensor may be shortened. As a result, in the high-speed operation optical sensor as described above, the level of the received signal is greatly changed depending on whether one pulse of the pulse disturbance light is accumulated or not during the exposure time, and the pulse disturbance light with respect to the received signal. There was a problem that it became more susceptible to the influence of.

そこで、本発明は、パルス外乱光を含む信号ノイズの周期と比較して光学式センサの露光時間が短い場合でも、当該信号ノイズを検出できる光学式センサを提供することを目的とする。 Therefore, an object of the present invention is to provide an optical sensor capable of detecting the signal noise even when the exposure time of the optical sensor is shorter than the period of the signal noise including pulse disturbance light.

本発明の一態様に係る光学式センサは、検出領域に光を投光する投光部と、検出領域からの光を受光して、受光量を示す受光信号を出力する受光部と、第１タイミングにおける第１受光信号のレベルと、第２タイミングにおける第２受光信号のレベルとを比較する比較部と、比較部による比較結果に基づいて、受光信号における信号ノイズの候補を出力する出力部と、を備える。 The optical sensor according to one aspect of the present invention includes a light projecting unit that projects light into a detection region, a light receiving unit that receives light from the detection region and outputs a light receiving signal indicating the amount of received light, and a first. A comparison unit that compares the level of the first light receiving signal at the timing with the level of the second light receiving signal at the second timing, and an output unit that outputs signal noise candidates in the received signal based on the comparison result by the comparison unit. , Equipped with.

この態様によれば、光学式センサは、異なるタイミングの二つの受光信号のレベルを比較して、当該比較結果に基づいて受光信号におけるパルス外乱光を含む信号ノイズの候補を出力するため、パルス外乱光の点灯周期と比較して露光時間が短い場合でもパルス外乱光を検出することができる。 According to this aspect, the optical sensor compares the levels of two received signals at different timings and outputs a candidate for signal noise including pulse disturbance light in the received signal based on the comparison result, so that the pulse disturbance Pulse disturbance light can be detected even when the exposure time is shorter than the lighting cycle of the light.

上記態様において、投光部は、１つのサイクル内に投光モードと非投光モードとを有し、出力部は、第１タイミングと第２タイミングとが、それぞれ異なるサイクルの非投光モードにおけるタイミングであり、かつ、比較結果に基づいて第１受光信号と第２受光信号とのレベル差が第１所定範囲内ではない場合、受光信号における信号ノイズの第１候補を出力してもよい。 In the above aspect, the light projecting unit has a light projecting mode and a non-light projecting mode in one cycle, and the output unit is in a non-light projecting mode in which the first timing and the second timing are different from each other. When it is the timing and the level difference between the first light receiving signal and the second light receiving signal is not within the first predetermined range based on the comparison result, the first candidate of the signal noise in the received light signal may be output.

光学式センサにおいて、非投光モード、すなわち、投光部からの投光がない状態において、パルス外乱光等の信号ノイズを蓄積したりしなかったりといった影響により異なるサイクルの第１受光信号と第２受光信号との間にレベル差が生じる場合（第１所定範囲内ではない場合）がある。この態様によれば、光学式センサは、上記のような場合、上記信号ノイズの候補を出力することで、当該信号ノイズを検出することができる。 In the optical sensor, the first received signal and the first received signal of different cycles are different depending on the influence of the non-light projecting mode, that is, the accumulation or non-accumulation of signal noise such as pulse disturbance light in the state where there is no light projecting from the light projecting section. 2 There is a case where a level difference occurs with the received signal (when it is not within the first predetermined range). According to this aspect, in the above case, the optical sensor can detect the signal noise by outputting the signal noise candidate.

上記態様において、出力部は、第１タイミングはサイクルの投光モードにおけるタイミングで第２タイミングは第１タイミングと同一のサイクルの非投光モードにおけるタイミングであり、かつ、比較結果に基づいて第１受光信号のレベルが第２受光信号のレベルより小さい場合、受光信号における信号ノイズの第２候補を出力してもよい。 In the above aspect, in the output unit, the first timing is the timing in the flood mode of the cycle, the second timing is the timing in the non-flood mode of the same cycle as the first timing, and the first timing is based on the comparison result. When the level of the received light signal is smaller than the level of the second received signal, the second candidate for signal noise in the received signal may be output.

光学式センサにおいて、パルス外乱光等の信号ノイズが蓄積した影響を受けて同一サイクルの投光モードにおける受光信号のレベルが非投光モードにおける受光信号のレベルより小さい場合がある。この態様によれば、光学式センサは、上記のような場合、上記信号ノイズの候補を出力することで、当該信号ノイズを検出することができる。 In the optical sensor, the level of the received signal in the flooded mode of the same cycle may be lower than the level of the received signal in the non-flooded mode due to the influence of accumulated signal noise such as pulse disturbance light. According to this aspect, in the above case, the optical sensor can detect the signal noise by outputting the signal noise candidate.

上記態様において、出力部は、第１タイミングと第２タイミングとが、それぞれ異なるサイクルの投光モードにおけるタイミングであり、かつ、比較結果に基づいて第１受光信号と第２受光信号とのレベル差が第２所定範囲内ではない場合、受光信号における信号ノイズの第３候補を出力してもよい。 In the above aspect, in the output unit, the first timing and the second timing are the timings in the projection mode of different cycles, and the level difference between the first light receiving signal and the second light receiving signal based on the comparison result. If is not within the second predetermined range, a third candidate for signal noise in the received signal may be output.

光学式センサにおいて、投光モード、すなわち、投光部からの投光がある状態において、パルス外乱光等の信号ノイズを蓄積したりしなかったりといった影響により異なるサイクルの第１受光信号と第２受光信号との間にレベル差が生じる場合（第２所定範囲内ではない場合）がある。この態様によれば、光学式センサは、上記のような場合、上記信号ノイズの候補を出力することで、当該信号ノイズを検出することができる。 In the optical sensor, the first light receiving signal and the second light receiving signal of different cycles are different depending on the influence of the light projection mode, that is, the accumulation or non-accumulation of signal noise such as pulse disturbance light in the state where the light is projected from the light projecting unit. There may be a level difference with the received signal (when it is not within the second predetermined range). According to this aspect, in the above case, the optical sensor can detect the signal noise by outputting the signal noise candidate.

上記態様において、出力部により出力された信号ノイズの第１候補、第２候補及び第３候補の少なくともいずれかに基づいて、総合的に受光信号における信号ノイズの有無を判定する判定部を備えてもよい。 In the above aspect, a determination unit for comprehensively determining the presence or absence of signal noise in the received signal based on at least one of the first candidate, the second candidate, and the third candidate of the signal noise output by the output unit is provided. May be good.

この態様によれば、光学式センサは、信号ノイズの複数の候補をふまえて、総合的に受光信号における信号ノイズの有無を判定することで、より精度よく信号ノイズを検出することができる。 According to this aspect, the optical sensor can detect signal noise more accurately by comprehensively determining the presence or absence of signal noise in the received signal based on a plurality of candidates for signal noise.

上記態様において、判定部により前記受光信号において前記信号ノイズ有りと判定された場合、前記サイクルを所定の変動量変更させるよう前記投光部及び前記受光部の少なくともいずれかを制御する投受光制御部を備えてもよい。 In the above aspect, when the determination unit determines that the signal noise is present in the light receiving signal, the light emitting / receiving control unit controls at least one of the light emitting unit and the light receiving unit so as to change the cycle by a predetermined fluctuation amount. May be provided.

この態様によれば、光学式センサは、受光信号において信号ノイズが有ると判断された場合に、投光部のサイクルを変更することで、信号ノイズの影響を受けにくいタイミングで投光することができるため、当該信号ノイズの影響を低減することができる。 According to this aspect, when it is determined that there is signal noise in the received signal, the optical sensor can project light at a timing that is not easily affected by the signal noise by changing the cycle of the light projecting unit. Therefore, the influence of the signal noise can be reduced.

本発明によれば、パルス外乱光を含む信号ノイズの周期と比較して光学式センサの露光時間が短い場合でも、当該信号ノイズを検出できる光学式センサを提供することができる。 According to the present invention, it is possible to provide an optical sensor capable of detecting the signal noise even when the exposure time of the optical sensor is shorter than the period of the signal noise including pulse disturbance light.

実施形態に係る光学式センサの概略ブロック図である。It is a schematic block diagram of the optical sensor which concerns on embodiment. 実施形態に係る投光部における投光タイミングと、受光部におけるシャッター開放タイミング及び受光信号の生成タイミングとの関係の一例を示したタイムチャートである。It is a time chart which showed an example of the relationship between the light projection timing in the light emitting part which concerns on embodiment, the shutter opening timing in a light receiving part, and the generation timing of a light receiving signal. 実施形態に係る投光部における投光タイミングと、受光部におけるシャッター開放タイミング及び受光信号の生成タイミングと、外乱光信号との関係の一例を示したタイムチャートである。It is a time chart which showed an example of the relationship between the light projection timing in the light projecting section, the shutter opening timing and the light receiving signal generation timing in the light receiving section, and the ambient light signal according to the embodiment. 実施形態に係る光学式センサの信号ノイズ検出及び投受光制御の動作の一例を示したフロー図である。It is a flow chart which showed an example of the operation of the signal noise detection and the light-receiving control of an optical sensor which concerns on embodiment. パルス外乱光と、従来の光学式センサの露光時間及び高速動作の光学式センサの露光時間との関係の一例を示したタイムチャートである。It is a time chart which showed an example of the relationship between the pulse disturbance light, the exposure time of a conventional optical sensor, and the exposure time of a high-speed operation optical sensor.

添付図面を参照して、本発明の好適な実施形態（以下「本実施形態」という。）について説明する。なお、各図において、同一の符号を付したものは、同一又は同様の構成を有する。 A preferred embodiment of the present invention (hereinafter referred to as “the present embodiment”) will be described with reference to the accompanying drawings. In each figure, those having the same reference numerals have the same or similar configurations.

＜１．構成例＞
図１を用いて、本実施形態に係る光学式センサ１の構成例について説明する。 <1. Configuration example>
A configuration example of the optical sensor 1 according to the present embodiment will be described with reference to FIG.

図１は、実施形態に係る光学式センサ１の概略ブロック図である。本実施形態に係る光学式センサ１は、検出対象物を、検出対象物の有無の判定や検出対象物までの距離の測定等を行って検出する（以下、単に「検出対象物を検出する」という）ための反射型の光学式センサであるが、これに限る主旨ではない。光学式センサ１は、例えば、透過型の光学式センサであってもよい。また、光学式センサ１は、ＴＯＦ（Time Of Flight）センサ等の３〜１０ｎｓｅｃ程度の非常に短いパルス幅のパルス光の投光を行うセンサであってもよい。 FIG. 1 is a schematic block diagram of the optical sensor 1 according to the embodiment. The optical sensor 1 according to the present embodiment detects the detection target by determining the presence or absence of the detection target, measuring the distance to the detection target, and the like (hereinafter, simply "detecting the detection target"). It is a reflection type optical sensor for (), but it is not limited to this. The optical sensor 1 may be, for example, a transmissive optical sensor. Further, the optical sensor 1 may be a sensor such as a TOF (Time Of Flight) sensor that projects pulsed light having a very short pulse width of about 3 to 10 nsec.

光学式センサ１は、投光部１０と、受光部２０と、制御部３０と、記憶部４０と、を備える。光学式センサ１は、例えば、検出領域に向けて投光部１０から光を投光し、検出領域からの反射光を受光部２０で受光する。 The optical sensor 1 includes a light emitting unit 10, a light receiving unit 20, a control unit 30, and a storage unit 40. For example, the optical sensor 1 projects light from the light projecting unit 10 toward the detection region, and receives the reflected light from the detection region by the light receiving unit 20.

投光部１０は、投光素子１１と、投光素子１１を駆動させる投光制御回路１２と、を備える。投光部１０は、１つのサイクル内に投光モードと非投光モードとを有し、投光モードの場合に検出領域に第１パラメータで指定された光を投光する。投光部１０からの投光がある状態を「投光モード」といい、投光がない状態を「非投光モード」という。 The light projecting unit 10 includes a light projecting element 11 and a light projecting control circuit 12 for driving the light projecting element 11. The light projecting unit 10 has a light projecting mode and a non-light projecting mode within one cycle, and in the case of the light projecting mode, the light specified by the first parameter is projected onto the detection region. The state in which the light is projected from the light projecting unit 10 is referred to as a "projection mode", and the state in which there is no light projection is referred to as a "non-projection mode".

「サイクル」とは、検出対象物の検出を行う周期であるが、投光部１０が投光処理を行う投光タイミングの間隔であってもよい。ここで図２を参照して、サイクルと投光部１０の投光タイミングとの関係の一例を説明する。図２は、投光部１０の投光タイミングと、受光素子２１のシャッター開放タイミングと、Ａ／Ｄ変換回路２３の受光信号の生成タイミングと、の関係の一例を表すタイムチャートである。図２に示すように、投光部１０の投光タイミングは、１つのサイクルの開始時において投光処理を行い、次のサイクルの開始時において次の投光処理を行うように設定されている。また、投光部１０は、各サイクルの投光処理後に一定時間投光がない状態を設けてもよい。 The “cycle” is a cycle for detecting the object to be detected, but may be an interval of the light projection timing at which the light projecting unit 10 performs the light projection process. Here, an example of the relationship between the cycle and the projection timing of the projection unit 10 will be described with reference to FIG. FIG. 2 is a time chart showing an example of the relationship between the light projection timing of the light projecting unit 10, the shutter opening timing of the light receiving element 21, and the generation timing of the light receiving signal of the A / D conversion circuit 23. As shown in FIG. 2, the light projecting timing of the light projecting unit 10 is set so that the light projecting process is performed at the start of one cycle and the next light projecting process is performed at the start of the next cycle. .. Further, the light projecting unit 10 may be provided with no light projecting for a certain period of time after the light projecting process of each cycle.

「第１パラメータ」とは、投光部１０の投光制御を行うために指定されるパラメータである。第１パラメータは、例えば、投光部１０の投光に適用される投光タイミング、及び投光部１０による投光強度の少なくともいずれかを含んでもよい。 The "first parameter" is a parameter designated for controlling the light projection of the light projecting unit 10. The first parameter may include, for example, at least one of the light projection timing applied to the light projection of the light projecting unit 10 and the light projection intensity by the light projecting unit 10.

投光素子１１は、検出領域に光を投光する素子である。投光素子１１は、例えば、レーザダイオードであってよいが、発光ダイオード等の素子で構成されてもよい。投光制御回路１２は、制御部３０からの第１パラメータを含む投光指令信号に基づいて、投光素子１１を駆動するための駆動信号を投光素子１１に出力する。 The light projecting element 11 is an element that projects light into the detection region. The light projecting element 11 may be, for example, a laser diode, but may be composed of an element such as a light emitting diode. The projection control circuit 12 outputs a drive signal for driving the projection element 11 to the projection element 11 based on the projection command signal including the first parameter from the control unit 30.

受光部２０は、受光素子２１と、信号処理回路２２と、Ａ／Ｄ変換回路２３と、を備える。受光部２０は、検出領域から光を第２パラメータで指定された感度で受光する。ここで「第２パラメータ」とは、受光部２０の受光制御を行うために指定されるパラメータである。第２パラメータは、例えば、受光部２０の受光に適用される受光期間、及び受光部２０の受光ゲインの少なくともいずれかを含んでもよい。 The light receiving unit 20 includes a light receiving element 21, a signal processing circuit 22, and an A / D conversion circuit 23. The light receiving unit 20 receives light from the detection region with the sensitivity specified by the second parameter. Here, the "second parameter" is a parameter designated for controlling the light reception of the light receiving unit 20. The second parameter may include, for example, at least one of the light receiving period applied to the light receiving of the light receiving unit 20 and the light receiving gain of the light receiving unit 20.

受光素子２１は、例えば、ＣＭＯＳセンサ素子又はＣＣＤセンサ素子等の撮像素子であり、シャッター機能を有してもよい。上記の受光期間は、例えば、受光素子２１がＣＭＯＳセンサ素子でありシャッター機能を有する場合、受光素子２１のシャッターの開放時間（以下、「シャッター開放時間」という）であってもよい。受光部２０は、例えば、受光素子２１が一次元の撮像素子の場合、後述の比較部３１による比較対象の受光信号として、一次元に配列された画素を探索して受光量分布のピークの光量を得てもよい。また、受光部２０は、受光素子２１が一次元の撮像素子の場合、比較部３１による比較対象の受光信号として、受光量分布のピーク以外の光量（例えば、ノイズフロア等のフロア値）を得てもよいし、受光量分布の平均光量を得てもよい。なお、光学式センサ１が三角測距方式を用いた測距センサの場合、このピークの画素位置によって検出対象物までの距離が測定される。また、光学式センサ１は、この測定された距離と予め設定された検出対象物の距離とに基づいて、検出対象物の有無を判定してもよい。受光素子２１がシャッター機能を有する場合、第２パラメータにシャッター開放時間を含めてもよい。 The light receiving element 21 is, for example, an image pickup element such as a CMOS sensor element or a CCD sensor element, and may have a shutter function. The light receiving period may be, for example, the shutter opening time of the light receiving element 21 (hereinafter, referred to as “shutter opening time”) when the light receiving element 21 is a CMOS sensor element and has a shutter function. For example, when the light receiving element 21 is a one-dimensional image sensor, the light receiving unit 20 searches for pixels arranged in one dimension as a light receiving signal to be compared by the comparison unit 31, which will be described later, and the light amount of the peak of the light receiving amount distribution. May be obtained. Further, when the light receiving element 21 is a one-dimensional image pickup element, the light receiving unit 20 obtains a light amount other than the peak of the light receiving amount distribution (for example, a floor value such as a noise floor) as a light receiving signal to be compared by the comparing unit 31. Alternatively, the average amount of light in the received light amount distribution may be obtained. When the optical sensor 1 is a distance measuring sensor using a triangular distance measuring method, the distance to the detection target is measured by the pixel position of this peak. Further, the optical sensor 1 may determine the presence / absence of the detection target object based on the measured distance and the preset distance of the detection target object. When the light receiving element 21 has a shutter function, the shutter opening time may be included in the second parameter.

信号処理回路２２は、受光素子２１から出力された信号に対して増幅等の処理をする。Ａ／Ｄ変換回路２３は、信号処理回路２２から出力された信号をデジタル信号に変換して受光量を表す受光信号を生成する。 The signal processing circuit 22 performs processing such as amplification on the signal output from the light receiving element 21. The A / D conversion circuit 23 converts the signal output from the signal processing circuit 22 into a digital signal to generate a light receiving signal representing the amount of light received.

図２を参照して、サイクルと受光素子２１のシャッター開放タイミングとＡ／Ｄ変換回路２３の受光信号の生成タイミングとの関係の一例を説明する。図２に示すように、（ｂ）受光素子２１のシャッター開放タイミングは、１つのサイクルの投光モード開始時においてシャッター開放処理を行い、また、同じサイクル内の非投光モードの開始時においてもシャッター開放処理を行うように設定されている。（ｃ）Ａ／Ｄ変換回路２３の受光信号の生成タイミングにおいて、投光モードと非投光モードのそれぞれのシャッター開放処理によって受光素子２１に受光された光に基づいて、投光モードの受光信号（図２の（ｃ）の（１））と非投光モードの受光信号（図２の（ｃ）の（２））とが生成される。このような構成によれば、受光素子２１は、投光部１０の投光モードと非投光モードとの両方の状態において受光信号を得ることができる。 An example of the relationship between the cycle, the shutter opening timing of the light receiving element 21, and the generation timing of the light receiving signal of the A / D conversion circuit 23 will be described with reference to FIG. As shown in FIG. 2, (b) the shutter release timing of the light receiving element 21 is such that the shutter release process is performed at the start of the floodlight mode in one cycle, and also at the start of the non-lightlight mode in the same cycle. It is set to perform shutter release processing. (C) At the generation timing of the light receiving signal of the A / D conversion circuit 23, the light receiving signal of the light emitting mode is based on the light received by the light receiving element 21 by the shutter opening processing of each of the light projecting mode and the non-light emitting mode. ((1) in (c) of FIG. 2) and a light receiving signal in the non-projection mode ((2) in (c) of FIG. 2) are generated. According to such a configuration, the light receiving element 21 can obtain a light receiving signal in both the light emitting mode and the non-light emitting mode of the light projecting unit 10.

制御部３０は、比較部３１と、出力部３２と、判定部３３と、投受光制御部３４と、を備える。制御部３０は、後述の記憶部４０に格納されたプログラムに基づき検出対象物の検出に係る処理を実行する。制御部３０は、例えば、ＣＰＵ（Central Processing Unit）又はＦＰＧＡ (Field Programmable Gate Array）等で構成されている。 The control unit 30 includes a comparison unit 31, an output unit 32, a determination unit 33, and a light emitting / receiving control unit 34. The control unit 30 executes a process related to the detection of the detection target based on the program stored in the storage unit 40 described later. The control unit 30 is composed of, for example, a CPU (Central Processing Unit), an FPGA (Field Programmable Gate Array), or the like.

比較部３１は、第１タイミングにおける第１受光信号のレベルと、第２タイミングにおける第２受光信号のレベルとを比較する。比較部３１の比較にあたっては、例えば、（Ａ）第１受光信号のレベルと第２受光信号のレベルとの大小関係を評価する方法、（Ｂ）第１受光信号のレベルと第２受光信号のレベルとの差分（以下、「レベル差」という）を算出する方法、等の比較方法が考えられる。ここで「第１タイミング」とは、比較部３１により比較対象となる一方の受光信号（第１受光信号）に関するタイミングであり、「第２タイミング」とは、第１タイミングと異なるタイミングであり、比較部３１により比較対象となる他方の受光信号（第２受光信号）に関するタイミングである。第１タイミング及び第２タイミングは、例えば、投光部１０の異なる二つの投光タイミングであってもよいし、受光部２０の異なる二つの受光信号の生成タイミングであってもよい。 The comparison unit 31 compares the level of the first received signal at the first timing with the level of the second received signal at the second timing. In the comparison of the comparison unit 31, for example, (A) a method of evaluating the magnitude relationship between the level of the first received signal and the level of the second received signal, and (B) the level of the first received signal and the second received signal. A comparison method such as a method of calculating a difference from a level (hereinafter referred to as "level difference") can be considered. Here, the "first timing" is a timing relating to one of the light receiving signals (first light receiving signal) to be compared by the comparison unit 31, and the "second timing" is a timing different from the first timing. This is the timing regarding the other light receiving signal (second light receiving signal) to be compared by the comparison unit 31. The first timing and the second timing may be, for example, two different light projecting timings of the light projecting unit 10 or two different light receiving signal generation timings of the light receiving unit 20.

比較部３１は、例えば、異なるサイクルにおける非投光モードでの二つの受光信号同士を比較して、当該受光信号同士のレベル差を算出してもよい。比較部３１は、具体的には、それぞれ異なるサイクルの非投光モードにおける第１タイミングと第２タイミングとにおいて、第１タイミングにおける第１受光信号と第２タイミングにおける第２受光信号とのレベル差を算出してもよい。 The comparison unit 31 may, for example, compare two light-receiving signals in the non-light-emitting mode in different cycles and calculate the level difference between the light-receiving signals. Specifically, the comparison unit 31 describes the level difference between the first light receiving signal in the first timing and the second light receiving signal in the second timing in the first timing and the second timing in the non-flooding mode of different cycles. May be calculated.

比較部３１は、例えば、同一のサイクルにおける投光モードでの受光信号と非投光モードでの受光信号とを比較して、これらの受光信号間のレベルの大小関係を評価してもよい。比較部３１は、具体的には、サイクル内の投光モードにおけるタイミングの第１タイミングと、当該第１タイミングと同一のサイクル内の非投光モードにおけるタイミングの第２タイミングとにおいて、第１タイミングにおける第１受光信号のレベルと第２タイミングにおける第２受光信号のレベルとの大小関係を評価してもよい。 For example, the comparison unit 31 may compare the light-receiving signal in the floodlight mode and the light-received signal in the non-light-light mode in the same cycle to evaluate the magnitude relationship between the received light signals. Specifically, the comparison unit 31 sets the first timing in the first timing of the timing in the flooding mode in the cycle and the second timing of the timing in the non-flooding mode in the same cycle as the first timing. The magnitude relationship between the level of the first light receiving signal and the level of the second light receiving signal at the second timing may be evaluated.

比較部３１は、例えば、異なるサイクルにおける投光モードでの受光信号同士を比較して、当該受光信号同士のレベル差を算出してもよい。比較部３１は、具体的には、それぞれ異なるサイクルの投光モードにおける第１タイミングと第２タイミングとにおいて、第１タイミングにおける第１受光信号と第２タイミングにおける第２受光信号とのレベル差を算出してもよい。 For example, the comparison unit 31 may compare the received light signals in the light projection mode in different cycles and calculate the level difference between the received light signals. Specifically, the comparison unit 31 determines the level difference between the first light receiving signal in the first timing and the second light receiving signal in the second timing in the first timing and the second timing in the projection modes having different cycles. It may be calculated.

図３を参照して、比較部３１における二つの受光信号の比較方法の一例について説明する。図３は、投光部１０の投光タイミングと、受光素子２１のシャッター開放タイミングと、Ａ／Ｄ変換回路２３の受光信号の生成タイミングと、受光信号における信号ノイズとして受光素子２１で受光されたパルス外乱光の信号（以下、単に「外乱光信号」という）との関係の一例を表すタイムチャートである。本例では、下記（ア）〜（ウ）の３つの比較パターンを用いる例を説明する。また、本例では、１サイクル（ｔＡ）の期間を１００μｓ、１サイクル内の投光モードの期間（ｔＢ）をｔＡ／２（５０μｓ）、１サイクル内の非投光モードの期間（ｔＣ）をｔＡ／２（５０μｓ）とする。 An example of a method of comparing two received signals in the comparison unit 31 will be described with reference to FIG. FIG. 3 shows the light projection timing of the light projecting unit 10, the shutter opening timing of the light receiving element 21, the generation timing of the light receiving signal of the A / D conversion circuit 23, and the light receiving by the light receiving element 21 as signal noise in the light receiving signal. It is a time chart which shows an example of the relationship with the signal of a pulse disturbance light (hereinafter, simply referred to as "a disturbance light signal"). In this example, an example using the following three comparison patterns (a) to (c) will be described. Further, in this example, the period of one cycle (tA) is 100 μs, the period of the projection mode (tB) within one cycle is tA / 2 (50 μs), and the period of the non-illumination mode within one cycle (tC). It is tA / 2 (50 μs).

（ア）図３に示すように、（ｄ）外乱光信号のポイントＰ１では、１サイクル内の投光モードの（ａ）に示す投光期間と（ｂ）に示すシャッター開放時間とが重なる露光時間において、外乱光信号は点灯状態にある。このため、（ｃ）Ａ／Ｄ変換回路２３で生成された受光信号（１）のレベルは、投光部１０からの投光による受光信号にこの点灯状態の外乱光信号の影響を受けたレベルとなる。一方、外乱光信号のポイントＰ２では、同じサイクル内の非投光モードの（ｂ）に示すシャッター開放時間において外乱光信号は消灯状態にある。このため、（ｃ）Ａ／Ｄ変換回路２３で生成された受光信号（２）のレベルは、投光部１０からの投光による受光信号がなく、また、外乱光信号の影響も受けないレベルとなる。このような場合、比較部３１は、同一のサイクルにおける投光モードでの受光信号（１）のレベルと非投光モードでの受光信号（２）のレベルとの大小関係を評価し、受光信号（１）のレベルは、受光信号（２）のレベルより大きいと評価する。 (A) As shown in FIG. 3, at (d) point P1 of the disturbance light signal, the exposure in which the light projection period shown in (a) and the shutter opening time shown in (b) of the light projection mode within one cycle overlap. In time, the ambient light signal is lit. Therefore, (c) the level of the light receiving signal (1) generated by the A / D conversion circuit 23 is the level at which the light receiving signal generated by the light projected from the light projecting unit 10 is affected by the disturbance light signal in this lighting state. It becomes. On the other hand, at the point P2 of the disturbance light signal, the disturbance light signal is in the extinguished state during the shutter opening time shown in (b) of the non-flooding mode in the same cycle. Therefore, (c) the level of the light receiving signal (2) generated by the A / D conversion circuit 23 is a level at which there is no light receiving signal due to the light projected from the light projecting unit 10 and the level is not affected by the ambient light signal. It becomes. In such a case, the comparison unit 31 evaluates the magnitude relationship between the level of the light receiving signal (1) in the floodlight mode and the level of the light receiving signal (2) in the non-lightning mode in the same cycle, and evaluates the light receiving signal It is evaluated that the level of (1) is larger than the level of the received signal (2).

「露光時間」とは、受光部２０における受光期間の長さをいう。露光時間は、例えば、投光期間と受光期間とが異なる場合には、両期間が重複する期間としてもよいし、投光期間が受光期間より早く開始し受光期間が投光期間より遅く終了する場合には、投光期間が開始されてから受光期間が終了するまでの期間としてもよい。露光時間は、具体的には、受光素子２１がＣＭＯＳセンサ素子やＣＣＤセンサ素子でありシャッター機能を有する場合、受光素子２１のシャッターの開放期間と、投光素子１１の投光期間との重なりの時間に相当する。また、露光時間は、別の例として、受光素子２１がフォトダイオード等の単一受光素子の場合、受光量のサンプリング期間に相当する。 The "exposure time" refers to the length of the light receiving period in the light receiving unit 20. The exposure time may be, for example, a period in which both periods overlap when the light emitting period and the light receiving period are different, or the light emitting period starts earlier than the light receiving period and ends later than the light emitting period. In this case, it may be the period from the start of the light projection period to the end of the light receiving period. Specifically, when the light receiving element 21 is a CMOS sensor element or a CCD sensor element and has a shutter function, the exposure time is the overlap between the shutter opening period of the light receiving element 21 and the light emitting period of the light projecting element 11. Corresponds to time. Further, as another example, when the light receiving element 21 is a single light receiving element such as a photodiode, the exposure time corresponds to the sampling period of the light receiving amount.

（イ）図３の（ｄ）外乱光信号のポイントＰ３では、上記の受光信号（１）とは異なるサイクル内の投光モードの露光時間において、外乱光信号は消灯状態にある。このため、（ｃ）Ａ／Ｄ変換回路２３で生成された受光信号（３）のレベルは、この消灯状態の外乱光信号、すなわち、外乱光の影響を受けないレベルとなる。比較部３１は、異なるサイクルにおける投光モードでの受光信号（１）と受光信号（３）とのレベル差を算出する。 (A) At the point P3 of the disturbance light signal (d) in FIG. 3, the disturbance light signal is in the extinguished state at the exposure time of the projection mode in the cycle different from the received light signal (1). Therefore, (c) the level of the received light signal (3) generated by the A / D conversion circuit 23 is a level that is not affected by the ambient light signal in the extinguished state, that is, the ambient light. The comparison unit 31 calculates the level difference between the light receiving signal (1) and the light receiving signal (3) in the light projection mode in different cycles.

（ウ）図３の（ｄ）外乱光信号のポイントＰ４では、上記の受光信号（２）とは異なるサイクル内の非投光モードのシャッター開放時間において、外乱光信号は点灯状態にある。このため、（ｃ）Ａ／Ｄ変換回路２３で生成された受光信号（４）のレベルは、投光部１０からの投光による受光信号はなく、外乱光信号による影響を受けたレベルとなる。比較部３１は、異なるサイクルにおける非投光モードでの受光信号（２）と受光信号（４）とのレベル差を算出する。 (C) At the point P4 of the disturbance light signal (d) in FIG. 3, the disturbance light signal is in the lit state at the shutter opening time in the non-light projection mode within the cycle different from the received light signal (2). Therefore, (c) the level of the light receiving signal (4) generated by the A / D conversion circuit 23 is a level affected by the disturbance light signal without the light receiving signal due to the light projected from the light projecting unit 10. .. The comparison unit 31 calculates the level difference between the light receiving signal (2) and the light receiving signal (4) in the non-light projection mode in different cycles.

出力部３２は、比較部３１による比較結果に基づいて、受光信号における信号ノイズの候補を出力する。出力部３２は、例えば、比較部３１の上記（Ａ）の比較方法による比較結果に基づいて二つの受光信号のレベル間の大小関係が外乱光信号の影響を受けない場合と比べて異なる場合、比較対象の受光信号が信号ノイズの影響を受けている（又はその可能性がある）旨の出力をしてもよい。また、出力部３２は、例えば、比較部３１の上記（Ｂ）の比較方法による比較結果に基づいて二つの受光信号間のレベル差が外乱光信号の影響を受けない場合と比べて異なる場合、比較対象の受光信号が信号ノイズの影響を受けている等の旨の出力をしてもよい。また、出力部３２は、例えば、上記のような信号ノイズの影響を受けている（又はその可能性がある）受光信号を特定する旨の出力をしてもよい。 The output unit 32 outputs a candidate for signal noise in the received signal based on the comparison result by the comparison unit 31. In the output unit 32, for example, when the magnitude relationship between the levels of the two received light signals is different from the case where the disturbance light signal is not affected, based on the comparison result of the comparison method (A) of the comparison unit 31. An output indicating that the received signal to be compared is affected by (or may be) signal noise may be output. Further, when the output unit 32 is different from the case where the level difference between the two received light signals is different from the case where it is not affected by the disturbance light signal, for example, based on the comparison result by the comparison method of the above (B) of the comparison unit 31. An output indicating that the received signal to be compared is affected by signal noise may be output. Further, the output unit 32 may output, for example, to specify a received signal that is affected by (or may be affected by) the signal noise as described above.

上記構成によれば、光学式センサ１は、異なるタイミングの二つの受光信号のレベルの比較結果に基づいて受光信号におけるパルス外乱光を含む信号ノイズの候補を出力するため、パルス外乱光の点灯周期と比較して露光時間が短い場合でも信号ノイズを検出することができる。 According to the above configuration, since the optical sensor 1 outputs signal noise candidates including pulse disturbance light in the received signal based on the comparison result of the levels of the two received signals at different timings, the lighting cycle of the pulse disturbance light The signal noise can be detected even when the exposure time is shorter than that of the above.

出力部３２は、例えば、比較部３１の比較結果に基づいて、異なるサイクルにおける非投光モードでの二つの受光信号同士のレベル差が第１所定範囲内ではない場合、当該レベル差を生じさせる信号ノイズの候補（以下、「第１候補」という）が存在するとして、その信号ノイズの第１候補を出力してもよい。ここで、「第１所定範囲」とは、非投光モードでの異なるタイミングにおける受光信号同士が同一又は略同一レベルにあることを判定するための範囲である。 The output unit 32 causes the level difference, for example, based on the comparison result of the comparison unit 31, when the level difference between the two received light signals in the non-projection mode in different cycles is not within the first predetermined range. Assuming that there is a signal noise candidate (hereinafter, referred to as "first candidate"), the first candidate of the signal noise may be output. Here, the "first predetermined range" is a range for determining that the received signals at different timings in the non-projection mode are at the same or substantially the same level.

出力部３２の出力にあたっては、光学式センサ１において検出対象物を検出する際の受光信号の計測に影響する信号ノイズが検出できればよい。このため、仮に信号ノイズが受光信号に含まれていても、比較部３１において上記レベル差を算出する際に当該信号ノイズの成分が相殺されて当該レベル差が生じなければ、出力部３２において信号ノイズの第１候補が出力されなくてもよい。このことは、後述の同一サイクル内の投光モードと非投光モードの二つの受光信号間の大小関係、及び異なるサイクルの投光モードでの二つの受光信号同士のレベル差においても同様である。 For the output of the output unit 32, it is sufficient that the optical sensor 1 can detect signal noise that affects the measurement of the received light signal when detecting the object to be detected. Therefore, even if signal noise is included in the received signal, if the component of the signal noise is canceled out when the comparison unit 31 calculates the level difference and the level difference does not occur, the output unit 32 signals. The first candidate for noise does not have to be output. This also applies to the magnitude relationship between the two received signals in the flooded mode and the non-flooded mode in the same cycle, which will be described later, and the level difference between the two received signals in the flooded modes in different cycles. ..

出力部３２は、例えば、第１タイミングと第２タイミングとが、それぞれ異なるサイクルの非投光モードにおけるタイミングであり、かつ、比較部３１の比較結果に基づいて第１タイミングにおける第１受光信号と第２タイミングにおける第２受光信号とのレベル差が第１所定範囲内ではない場合、受光信号における信号ノイズの第１候補を出力してもよい。 In the output unit 32, for example, the first timing and the second timing are timings in the non-light projection mode of different cycles, and the first light receiving signal in the first timing is obtained based on the comparison result of the comparison unit 31. When the level difference from the second received signal at the second timing is not within the first predetermined range, the first candidate of the signal noise in the received signal may be output.

光学式センサ１において、非投光モード、すなわち、投光部１０からの投光がない状態において、パルス外乱光等の信号ノイズを蓄積したりしなかったりといった影響により異なるサイクルの第１受光信号と第２受光信号との間にレベル差が生じる場合（第１所定範囲内ではない場合）がある。上記構成によれば、光学式センサ１は、このような場合でも、上記比較結果に基づいて信号ノイズの第１候補を出力することで、当該信号ノイズを検出することができる。 In the optical sensor 1, the first light receiving signal of a different cycle depends on the influence of the non-light projecting mode, that is, the accumulation or non-accumulation of signal noise such as pulse disturbance light in the state where the light projecting unit 10 does not project light. There is a case where a level difference occurs between the light receiving signal and the second light receiving signal (when it is not within the first predetermined range). According to the above configuration, even in such a case, the optical sensor 1 can detect the signal noise by outputting the first candidate of the signal noise based on the comparison result.

出力部３２は、例えば、比較部３１の比較結果に基づいて、同一のサイクルにおける投光モードでの受光信号のレベルが非投光モードでの受光信号のレベルより小さい場合、非投光モードでの受光信号のレベルに影響を及ぼす信号ノイズの候補（以下、「第２候補」という）が存在するとして、その信号ノイズの第２候補を出力してもよい。出力部３２は、具体的には、第１タイミングはサイクルの投光モードにおけるタイミングで第２タイミングは当該第１タイミングと同一のサイクルの非投光モードにおけるタイミングであり、かつ、比較部３１の比較結果に基づいて第１受光信号のレベルが第２受光信号のレベルより小さい場合、受光信号における信号ノイズの第２候補を出力してもよい。 The output unit 32 is set to the non-projection mode when, for example, the level of the received signal in the floodlight mode in the same cycle is lower than the level of the received signal in the non-projection mode based on the comparison result of the comparison unit 31. Assuming that there is a signal noise candidate (hereinafter, referred to as “second candidate”) that affects the level of the received signal of the above, the second candidate of the signal noise may be output. Specifically, in the output unit 32, the first timing is the timing in the projection mode of the cycle, the second timing is the timing in the non-illumination mode of the same cycle as the first timing, and the comparison unit 31 When the level of the first received light signal is smaller than the level of the second received light signal based on the comparison result, the second candidate of the signal noise in the received light signal may be output.

光学式センサ１において、パルス外乱光等の信号ノイズが蓄積した影響を受けて同一サイクルの投光モードにおける受光信号のレベルが非投光モードにおける受光信号のレベルより小さい場合がある。上記構成によれば、光学式センサ１は、このような場合でも、上記比較結果に基づいて信号ノイズの第２候補を出力することで、当該信号ノイズを検出することができる。 In the optical sensor 1, the level of the received signal in the flooded mode of the same cycle may be lower than the level of the received signal in the non-flooded mode due to the influence of accumulated signal noise such as pulse disturbance light. According to the above configuration, even in such a case, the optical sensor 1 can detect the signal noise by outputting the second candidate of the signal noise based on the comparison result.

出力部３２は、例えば、比較部３１の比較結果に基づいて、異なるサイクルにおける投光モードでの二つの受光信号同士のレベル差が第２所定範囲内ではない場合、当該レベル差を生じさせる信号ノイズの候補（以下、「信号ノイズの第３候補」という）が存在するとして、その信号ノイズの第３候補を出力してもよい。ここで、「第２所定範囲」とは、投光モードでの受光信号同士が同一又は略同一レベルにあることを判定するための範囲である。 Based on the comparison result of the comparison unit 31, for example, the output unit 32 is a signal that causes the level difference when the level difference between the two received light signals in the floodlight mode in different cycles is not within the second predetermined range. Assuming that there is a noise candidate (hereinafter, referred to as "third candidate for signal noise"), the third candidate for the signal noise may be output. Here, the "second predetermined range" is a range for determining that the received light signals in the floodlight mode are at the same or substantially the same level.

出力部３２は、例えば、第１タイミングと第２タイミングとが、それぞれ異なるサイクルの投光モードにおけるタイミングであり、かつ、比較部３１の比較結果に基づいて第１受光信号と第２受光信号とのレベル差が第２所定範囲内ではない場合、受光信号における信号ノイズの第３候補を出力してもよい。 In the output unit 32, for example, the first timing and the second timing are timings in different cycles of the projection mode, and the first light receiving signal and the second light receiving signal are based on the comparison result of the comparison unit 31. When the level difference of is not within the second predetermined range, a third candidate for signal noise in the received signal may be output.

光学式センサ１において、投光モード、すなわち、投光部１０からの投光がある状態において、パルス外乱光等の信号ノイズを蓄積したりしなかったりといった影響により異なるサイクルの第１受光信号と第２受光信号との間にレベル差が生じる場合（第２所定範囲内ではない場合）がある。上記構成によれば、光学式センサ１は、このような場合でも、上記比較結果に基づいて信号ノイズの第３候補を出力することで、当該信号ノイズを検出することができる。 In the optical sensor 1, in the light projecting mode, that is, in the state where the light projecting from the light projecting unit 10 is present, the first light receiving signal having a different cycle depends on the influence of whether or not signal noise such as pulse disturbance light is accumulated. There is a case where a level difference occurs with the second received signal (when it is not within the second predetermined range). According to the above configuration, even in such a case, the optical sensor 1 can detect the signal noise by outputting the third candidate of the signal noise based on the comparison result.

図３を参照して、出力部３２における二つの受光信号の比較結果に基づく信号ノイズの候補の出力方法の一例について説明する。 With reference to FIG. 3, an example of an output method of signal noise candidates based on the comparison result of the two received signals in the output unit 32 will be described.

出力部３２は、例えば、上記（ア）の比較パターンの場合、比較部３１の投光モードの受光信号（１）のレベルは、非投光モードの受光信号（２）のレベルより大きいと評価する比較結果に基づいて、信号ノイズの第２候補は存在しないとして出力しない。 For example, in the case of the comparison pattern of (a) above, the output unit 32 evaluates that the level of the light receiving signal (1) in the floodlight mode of the comparison unit 31 is higher than the level of the light receiving signal (2) in the non-lightlight mode. Based on the comparison result, the second candidate for signal noise is not output as it does not exist.

出力部３２は、例えば、上記（イ）の比較パターンの場合、比較部３１による算出された異なるサイクルにおける投光モードでの受光信号（１）のレベルと受光信号（３）のレベル差とする比較結果に基づいて、当該レベル差を生じさせる信号ノイズの第３候補が存在するとして、その信号ノイズの第３候補を出力する。この場合、信号ノイズの第３候補は、（ｄ）外乱光信号である。 For example, in the case of the comparison pattern of (a) above, the output unit 32 is the level difference between the light receiving signal (1) and the light receiving signal (3) in the floodlight mode calculated by the comparison unit 31 in different cycles. Based on the comparison result, assuming that there is a third candidate for the signal noise that causes the level difference, the third candidate for the signal noise is output. In this case, the third candidate for signal noise is (d) ambient light signal.

出力部３２は、例えば、上記（ウ）の比較パターンの場合、比較部３１の比較結果に基づいて、非投光モードの受光信号同士のレベル差を生じさせる信号ノイズの第１候補が存在するとして、その信号ノイズの第１候補を出力する。この場合、信号ノイズの第１候補は、（ｄ）外乱光信号である。 For example, in the case of the comparison pattern (c) described above, the output unit 32 has a first candidate for signal noise that causes a level difference between the received signals in the non-projection mode based on the comparison result of the comparison unit 31. As a result, the first candidate for the signal noise is output. In this case, the first candidate for signal noise is (d) ambient light signal.

判定部３３は、出力部３２により出力された信号ノイズの候補に基づいて、受光信号における信号ノイズの有無を判定する。判定部３３は、例えば、出力部３２により出力された第１候補、第２候補及び第３候補の少なくともいずれかに基づいて、総合的に受光信号における信号ノイズの有無を判定してもよい。 The determination unit 33 determines the presence or absence of signal noise in the received signal based on the signal noise candidates output by the output unit 32. The determination unit 33 may comprehensively determine the presence or absence of signal noise in the received signal based on at least one of the first candidate, the second candidate, and the third candidate output by the output unit 32, for example.

判定部３３は、例えば、信号ノイズの第１候補、第２候補及び第３候補のいずれか一つでも出力されれば受光信号において信号ノイズ有りと判定してもよい。別の例として、判定部３３は、第１候補、第２候補及び第３候補に優先度を設定して、優先度の高い信号ノイズの候補が出力された場合は、信号ノイズが有ると判定してもよい。判定部３３は、具体的には、第１候補を優先度「高」、第２候補を優先度「中」、第３候補を優先度「低」に設定し、優先度「高」の第１候補のみ出力された場合は信号ノイズ有りと判定し、一方優先度「低」の第３候補のみ出力された場合は信号ノイズ無しと判定してもよい。判定部３３は、例えば、図３の例において、上記のように信号ノイズの候補ごとに優先度を設定した場合、優先度「高」の第１候補が出力されたため、信号ノイズ有りと判定してもよい。 The determination unit 33 may determine, for example, that there is signal noise in the received signal if any one of the first candidate, the second candidate, and the third candidate of the signal noise is output. As another example, the determination unit 33 sets priorities for the first candidate, the second candidate, and the third candidate, and when a signal noise candidate having a high priority is output, it is determined that there is signal noise. You may. Specifically, the determination unit 33 sets the first candidate as the priority "high", the second candidate as the priority "medium", and the third candidate as the priority "low", and the first candidate has the priority "high". If only one candidate is output, it may be determined that there is signal noise, while if only the third candidate having a priority of "low" is output, it may be determined that there is no signal noise. For example, in the example of FIG. 3, when the priority is set for each signal noise candidate as described above, the determination unit 33 determines that there is signal noise because the first candidate having the priority “high” is output. You may.

判定部３３は、別の例として、信号ノイズの第１候補、第２候補及び第３候補ごとに又は信号ノイズの候補全体で出力回数の閾値を設けて、所定期間内の当該出力回数が当該閾値を超えた場合に信号ノイズ有りと判定してもよい。 As another example, the determination unit 33 sets a threshold value for the number of outputs for each of the first, second, and third candidates for signal noise, or for the entire signal noise candidate, and the number of outputs within a predetermined period is the said. When the threshold value is exceeded, it may be determined that there is signal noise.

上記構成によれば、光学式センサ１は、信号ノイズの複数の候補をふまえて、総合的に受光信号における信号ノイズの有無を判定することで、より精度よく信号ノイズを検出することができる。 According to the above configuration, the optical sensor 1 can detect signal noise more accurately by comprehensively determining the presence or absence of signal noise in the received signal based on a plurality of candidates for signal noise.

投受光制御部３４は、投光部１０の投光制御及び受光部２０の受光制御を行う。投受光制御部３４は、これらの制御にあたって、投光部１０の第１パラメータを調整してもよいし、受光部２０の第２パラメータを調整してもよい。投受光制御部３４は、例えば、判定部３３により受光信号において信号ノイズ有りと判定された場合、サイクルを所定の変動量変更させるよう投光部１０及び受光部２０の少なくともいずれかを制御してもよい。投受光制御部３４は、例えば、投光部１０の投光タイミング、及び受光部２０のシャッター開放タイミング等を変更させることで、１サイクルの長さを所定の変動量（例えば、変更前と比較して１０％延びるように１サイクルの長さを変更する等）変更させてもよい。 The light emitting / receiving control unit 34 controls the light projection of the light emitting unit 10 and the light receiving control of the light receiving unit 20. The light emitting / receiving control unit 34 may adjust the first parameter of the light emitting / receiving unit 10 or the second parameter of the light receiving unit 20 in these controls. For example, when the determination unit 33 determines that there is signal noise in the received signal, the light emitting / receiving control unit 34 controls at least one of the light emitting / receiving unit 10 and the light receiving unit 20 so as to change the cycle by a predetermined fluctuation amount. May be good. The light emitting / receiving control unit 34 changes the length of one cycle by, for example, changing the light emitting timing of the light emitting unit 10 and the shutter opening timing of the light receiving unit 20 (for example, comparing the length of one cycle with that before the change). Then, the length of one cycle may be changed so as to extend by 10%).

上記構成によれば、光学式センサ１は、受光信号において信号ノイズが有ると判断された場合に、サイクルを変更することで、信号ノイズの影響を受けにくいタイミングで投受光することができるため、当該信号ノイズの影響を低減することができる。 According to the above configuration, when it is determined that there is signal noise in the received signal, the optical sensor 1 can emit and receive light at a timing that is not easily affected by the signal noise by changing the cycle. The influence of the signal noise can be reduced.

制御部３０は、例えば、光学式センサ１において、パルスカウント処理を用いて測定された検出対象物までの距離と所定の閾値とを比較して出力の判定を行う場合、判定部３３により受光信号において信号ノイズ有りと判定された場合、信号ノイズ有りと判定された受光信号を計測対象外としてもよい。この際、光学式センサ１における上記出力の状態は前回値を保持としてもよい。このような構成によれば、制御部３０は、上記のような出力の判定において、信号ノイズによる影響を低減することができる。 When the control unit 30 determines the output by comparing the distance to the detection target measured by using the pulse count process with a predetermined threshold value in the optical sensor 1, for example, the light receiving signal is determined by the determination unit 33. If it is determined that there is signal noise in the above, the received signal determined to have signal noise may be excluded from the measurement target. At this time, the state of the output in the optical sensor 1 may hold the previous value. According to such a configuration, the control unit 30 can reduce the influence of signal noise in the determination of the output as described above.

記憶部４０は、検出対象物の有無の判定、検出対象物までの距離の測定や第１パラメータ及び第２パラメータの調整に係る処理を実行させるプログラムを記憶してもよい。また、記憶部４０は、光学式センサ１と通信可能に接続されている。すなわち、記憶部４０は、光学式センサ１内の制御部３０と通信可能に接続されていれば、光学式センサ１内部に設けてもよいし、光学式センサ１外部に設けてもよい。 The storage unit 40 may store a program for executing processing related to determination of the presence / absence of the detection target, measurement of the distance to the detection target, and adjustment of the first parameter and the second parameter. Further, the storage unit 40 is communicably connected to the optical sensor 1. That is, the storage unit 40 may be provided inside the optical sensor 1 or outside the optical sensor 1 as long as it is communicably connected to the control unit 30 in the optical sensor 1.

＜２．動作例＞
図４を用いて、本実施形態に係る光学式センサ１の信号ノイズ検出及び投受光制御の動作例を説明する。本例では、光学式センサ１の動作中常に信号ノイズの検出処理を実行し、信号ノイズ有りと判定された場合に自動でサイクルを変更するよう投受光制御を実行する例を用いて説明する。なお、他の例として、光学式センサ１は、例えば、ユーザに対して信号ノイズ有る旨の通知をしてユーザからの操作指示により手動でサイクルを変更させてもよい。 <2. Operation example>
An operation example of signal noise detection and light receiving / receiving control of the optical sensor 1 according to the present embodiment will be described with reference to FIG. In this example, the signal noise detection process is always executed during the operation of the optical sensor 1, and when it is determined that there is signal noise, the light emitting / receiving control is executed so as to automatically change the cycle. As another example, the optical sensor 1 may notify the user that there is signal noise and manually change the cycle according to an operation instruction from the user.

図４に示すように、比較部３１は、初期設定されたサイクルにおける２サイクル分の受光信号を受光部２０から取得する（Ｓ１０）。なお、比較部３１は、異なるサイクルにおける二つの受光信号を比較しない場合は、１サイクル分の受光信号を取得してもよい。比較部３１は、第１タイミングにおける第１受光信号のレベルと、第２タイミングにおける第２受光信号のレベルとを比較する（Ｓ１１）。 As shown in FIG. 4, the comparison unit 31 acquires the light receiving signals for two cycles in the initially set cycle from the light receiving unit 20 (S10). If the comparison unit 31 does not compare two light-receiving signals in different cycles, the comparison unit 31 may acquire the light-receiving signals for one cycle. The comparison unit 31 compares the level of the first light receiving signal at the first timing with the level of the second light receiving signal at the second timing (S11).

出力部３２は、比較部３１の比較結果に基づいて、信号ノイズの候補を出力する（Ｓ１２）。判定部３３は、出力部３２により出力された信号ノイズの候補に基づいて、受光信号における信号ノイズの有無を判定する（Ｓ１３）。判定部３３において受光信号において信号ノイズ有りと判定された場合（Ｓ１３のＹｅｓ）、投受光制御部３４は、サイクルを所定の変動量変更させるよう投光部１０及び受光部２０の少なくともいずれかを制御する（Ｓ１４）。判定部３３において受光信号において信号ノイズ無しと判定された場合（Ｓ１３のＮｏ）、投受光制御部３４は、サイクルを維持するよう投光部１０及び受光部２０の少なくともいずれかを制御する（Ｓ１５）。 The output unit 32 outputs a signal noise candidate based on the comparison result of the comparison unit 31 (S12). The determination unit 33 determines the presence or absence of signal noise in the received signal based on the signal noise candidates output by the output unit 32 (S13). When the determination unit 33 determines that there is signal noise in the light receiving signal (Yes in S13), the light emitting / receiving control unit 34 causes at least one of the light emitting unit 10 and the light receiving unit 20 to change the cycle by a predetermined fluctuation amount. Control (S14). When the determination unit 33 determines that there is no signal noise in the light receiving signal (No in S13), the light emitting / receiving control unit 34 controls at least one of the light emitting unit 10 and the light receiving unit 20 so as to maintain the cycle (S15). ).

比較部３１は、電源がＯＮの場合（Ｓ１６のＮｏ）、変更又は維持されたサイクルにおける２サイクル分の受光信号を受光部２０から取得し（Ｓ１７）、図４のフローのステップＳ１１の前に戻る。光学式センサ１は、電源がＯＦＦの場合（Ｓ１６のＹｅｓ）、信号ノイズの検出及び投受光制御の動作を終了する。 When the power is turned on (No in S16), the comparison unit 31 acquires the received signal for two cycles in the changed or maintained cycle from the light receiving unit 20 (S17), and before step S11 of the flow of FIG. Return. When the power is turned off (Yes in S16), the optical sensor 1 ends the operation of signal noise detection and light reception control.

以上説明した実施形態は、本発明の理解を容易にするためのものであり、本発明を限定して解釈するためのものではない。実施形態が備える各要素並びにその配置、材料、条件、形状及びサイズ等は、例示したものに限定されるわけではなく適宜変更することができる。また、異なる実施形態で示した構成同士を部分的に置換し又は組み合わせることが可能である。 The embodiments described above are for facilitating the understanding of the present invention, and are not for limiting and interpreting the present invention. Each element included in the embodiment and its arrangement, material, condition, shape, size, etc. are not limited to those exemplified, and can be changed as appropriate. In addition, the configurations shown in different embodiments can be partially replaced or combined.

本実施形態の一部又は全部は、以下の附記のようにも記載されうるが、以下には限られない。 A part or all of this embodiment may be described as in the appendix below, but is not limited to the following.

［附記］
検出領域に光を投光する投光部（１０）と、
前記検出領域からの光を受光して、受光量を示す受光信号を出力する受光部（２０）と、
第１タイミングにおける第１受光信号のレベルと、第２タイミングにおける第２受光信号のレベルとを比較する比較部（３１）と、
前記比較部による比較結果に基づいて、前記受光信号における信号ノイズの候補を出力する出力部（３２）と、を備える、
光学式センサ（１）。 [Appendix]
A light projecting unit (10) that projects light into the detection area,
A light receiving unit (20) that receives light from the detection region and outputs a light receiving signal indicating the amount of received light.
A comparison unit (31) that compares the level of the first received signal at the first timing with the level of the second received signal at the second timing.
An output unit (32) that outputs a candidate for signal noise in the received signal based on the comparison result by the comparison unit is provided.
Optical sensor (1).

１…光学式センサ、１０…投光部、１１…投光素子、１２…投光制御回路、２０…受光部、２１…受光素子、２２…信号処理回路、３０…制御部、３１…比較部、３２…出力部、３２…比較部、３３…判定部、３４…投受光制御部、４０…記憶部。 1 ... Optical sensor, 10 ... Light projecting unit, 11 ... Light projecting element, 12 ... Light projecting control circuit, 20 ... Light receiving unit, 21 ... Light receiving element, 22 ... Signal processing circuit, 30 ... Control unit, 31 ... Comparison unit , 32 ... Output unit, 32 ... Comparison unit, 33 ... Judgment unit, 34 ... Light emitting / receiving control unit, 40 ... Storage unit.

Claims

検出領域に光を投光する投光部と、
前記検出領域からの光を受光して、受光量を示す受光信号を出力する受光部と、
第１タイミングにおける第１受光信号のレベルと、第２タイミングにおける第２受光信号のレベルとを比較する比較部と、
前記比較部による比較結果に基づいて、前記受光信号における信号ノイズの候補を出力する出力部と、を備える、
光学式センサ。 A light projecting unit that projects light into the detection area,
A light receiving unit that receives light from the detection region and outputs a light receiving signal indicating the amount of received light.
A comparison unit that compares the level of the first received signal at the first timing with the level of the second received signal at the second timing.
An output unit that outputs a candidate for signal noise in the received signal based on the comparison result by the comparison unit is provided.
Optical sensor.

前記投光部は、１つのサイクル内に投光モードと非投光モードとを有し、
前記出力部は、前記第１タイミングと前記第２タイミングとが、それぞれ異なる前記サイクルの前記非投光モードにおけるタイミングであり、かつ、前記比較結果に基づいて前記第１受光信号と前記第２受光信号とのレベル差が第１所定範囲内ではない場合、前記受光信号における信号ノイズの第１候補を出力する、
請求項１に記載の光学式センサ。 The light projecting unit has a light projecting mode and a non-light projecting mode in one cycle.
In the output unit, the first timing and the second timing are different timings in the non-projection mode of the cycle, and the first light receiving signal and the second light receiving signal are based on the comparison result. When the level difference from the signal is not within the first predetermined range, the first candidate for signal noise in the received signal is output.
The optical sensor according to claim 1.

前記出力部は、前記第１タイミングは前記サイクルの前記投光モードにおけるタイミングで前記第２タイミングは前記第１タイミングと同一の前記サイクルの前記非投光モードにおけるタイミングであり、かつ、前記比較結果に基づいて前記第１受光信号のレベルが前記第２受光信号のレベルより小さい場合、前記受光信号における信号ノイズの第２候補を出力する、
請求項２に記載の光学式センサ。 In the output unit, the first timing is the timing in the flooding mode of the cycle, the second timing is the timing in the non-flooding mode of the same cycle as the first timing, and the comparison result. When the level of the first light receiving signal is smaller than the level of the second light receiving signal based on the above, the second candidate of the signal noise in the light receiving signal is output.
The optical sensor according to claim 2.

前記出力部は、前記第１タイミングと前記第２タイミングとが、それぞれ異なる前記サイクルの前記投光モードにおけるタイミングであり、かつ、前記比較結果に基づいて前記第１受光信号と前記第２受光信号とのレベル差が第２所定範囲内ではない場合、前記受光信号における信号ノイズの第３候補を出力する、
請求項３に記載の光学式センサ。 In the output unit, the first timing and the second timing are different timings in the projection mode of the cycle, and the first light receiving signal and the second light receiving signal are based on the comparison result. When the level difference from and is not within the second predetermined range, the third candidate for signal noise in the received signal is output.
The optical sensor according to claim 3.

前記出力部により出力された前記信号ノイズの前記第１候補、前記第２候補及び前記第３候補の少なくともいずれかに基づいて、総合的に前記受光信号における信号ノイズの有無を判定する判定部を備える、
請求項４に記載の光学式センサ。 A determination unit that comprehensively determines the presence or absence of signal noise in the received signal based on at least one of the first candidate, the second candidate, and the third candidate of the signal noise output by the output unit. Prepare, prepare
The optical sensor according to claim 4.

前記判定部により前記受光信号において前記信号ノイズ有りと判定された場合、前記サイクルを所定の変動量変更させるよう前記投光部及び前記受光部の少なくともいずれかを制御する投受光制御部を備える、
請求項５に記載の光学式センサ。 When the determination unit determines that there is signal noise in the light receiving signal, the light emitting / receiving control unit is provided to control at least one of the light emitting unit and the light receiving unit so as to change the cycle by a predetermined fluctuation amount.
The optical sensor according to claim 5.