JPH073882B2 - Ambient light compensation method for photo sensor and its circuit - Google Patents
Ambient light compensation method for photo sensor and its circuitInfo
- Publication number
- JPH073882B2 JPH073882B2 JP10835786A JP10835786A JPH073882B2 JP H073882 B2 JPH073882 B2 JP H073882B2 JP 10835786 A JP10835786 A JP 10835786A JP 10835786 A JP10835786 A JP 10835786A JP H073882 B2 JPH073882 B2 JP H073882B2
- Authority
- JP
- Japan
- Prior art keywords
- light
- component
- pulse
- receiving element
- disturbance
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 230000007257 malfunction Effects 0.000 description 3
- 230000004043 responsiveness Effects 0.000 description 3
- 230000035945 sensitivity Effects 0.000 description 3
- 230000010354 integration Effects 0.000 description 2
- 230000001360 synchronised effect Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
Landscapes
- Photo Coupler, Interrupter, Optical-To-Optical Conversion Devices (AREA)
Description
【発明の詳細な説明】 産業上の利用分野 この発明は、ウェハカセット内のウェハの有無確認など
に用いるフオトセンサに関するもので、更に述べると、
フオトセンサが、外乱光により誤作動するのを防止する
ための外乱光補償方法及びその回路に関するものであ
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photo sensor used for confirming the presence / absence of a wafer in a wafer cassette.
The present invention relates to a disturbance light compensation method and a circuit for preventing the photo sensor from malfunctioning due to disturbance light.
従来の技術 ウエハカセツト内のウエハは、フオトセンサにより自動
的に、その有無が確認されている。2. Description of the Related Art The presence / absence of a wafer in a wafer cassette is automatically confirmed by a photo sensor.
従来のフオトセンサでは、発光素子と受光素子を対向し
て設け、発光素子を直流点灯し、ウエハカセツト内にウ
エハが収容されていないと、その光は、受光素子に入
り、電気信号に変換される。In the conventional photo sensor, the light emitting element and the light receiving element are provided so as to face each other, the light emitting element is turned on by direct current, and if the wafer is not housed in the wafer cassette, the light enters the light receiving element and is converted into an electric signal. .
しかし、この受光素子には、発光素子の光の他、外乱光
も入るため、この外乱光により誤作動を生ずることがあ
る。However, in addition to the light from the light-emitting element, ambient light enters the light-receiving element, and this ambient light may cause a malfunction.
そこで、この誤作動を防止するため、フオトセンサに
は、外乱光補償回路が設けられている。Therefore, in order to prevent this malfunction, the photo sensor is provided with a disturbance light compensation circuit.
この補償回路は、発光素子をパルス発生器に接続して信
号成分をパルス点灯すると共に、受光素子を同期検波器
に接続し、受光素子に入る外乱光成分を同期検波器で除
去し、直流信号を取り出すものである。This compensation circuit connects a light emitting element to a pulse generator to pulse-light a signal component, connects a light receiving element to a synchronous detector, removes disturbance light components entering the light receiving element with a synchronous detector, and outputs a DC signal. To take out.
発明が解決しようとする問題 従来例のフオトセンサの外乱光補償回路では、外乱光の
影響は受けにくいが、完全にその影響を除去できない。Problems to be Solved by the Invention Although the disturbance light compensation circuit of the conventional photo sensor is not easily affected by the disturbance light, the influence cannot be completely removed.
そこで、積分器の積分定数を更に大きくして、外乱光の
影響をより少なくすることも考えられるが、このように
すると、応答性および感度が共に低下する。Therefore, it is conceivable to further increase the integration constant of the integrator to reduce the influence of ambient light, but if this is done, both the responsiveness and the sensitivity decrease.
この発明は、上記事情に鑑み、応答性や感度を低下させ
ることなく完全に外乱光の影響を除去できるフオトセン
サの外乱光補償回路を提供することを目的とする。SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a disturbance light compensation circuit for a photo sensor, which can completely remove the influence of disturbance light without lowering the responsiveness or sensitivity.
問題点を解決するための手段 この発明は、パルス発生器に接続され、かつ、外乱光の
周波数よりも高い周波数でパルス点灯する発光素子と受
光素子とを互いに対向するように配設し、該受光素子の
出力側に、抵抗R1の一端を接続するとともに、同じ受光
素子の出力側に外乱光成分のみを通すローパスフィルタ
と該外乱光成分を逆極性にする極性反転アンプ及び別の
抵抗R2の一端を順次直列に接続し、前記各抵抗R1、R2の
それぞれの他端を接続点に連結し、該接続点で前記各抵
抗R1、R2からの各出力を加算してパルス成分のみを求
め、該パルス成分を積算器に入力して直流信号に変換
し、受光量に比例した信号を取り出すこと、により前記
問題を解決しようとするものである。Means for Solving the Problems In the present invention, a light emitting element and a light receiving element which are connected to a pulse generator and which are pulse-lighted at a frequency higher than the frequency of disturbance light are arranged so as to face each other, and Connect one end of the resistor R 1 to the output side of the light receiving element, and pass a disturbance light component only to the output side of the same light receiving element, a polarity inverting amplifier that reverses the disturbance light component and another resistor R. One end of 2 is sequentially connected in series, and the other end of each of the resistors R 1 and R 2 is connected to a connection point, and the outputs from the resistors R 1 and R 2 are added at the connection point. The above problem is solved by obtaining only a pulse component, inputting the pulse component into an integrator, converting it into a DC signal, and taking out a signal proportional to the amount of received light.
作用 パルス発生器により発光素子がパルス点灯すると、その
光は、外乱光と共に受光素子に入り、電流に変換され
る。When the light emitting element is pulse-lighted by the action pulse generator, the light enters the light receiving element together with the ambient light and is converted into a current.
この変換された電流は一方では、そのまま抵抗R1を介し
て接続点に流れ、他方では、ローパスフイルタによりパ
ルス成分が取り除かれ、外乱光成分のみが極性反転アン
プに入り、その極性が反転された後、抵抗２を介して接
続点に流れる。On the one hand, this converted current flows through the resistor R1 to the connection point as it is, and on the other hand, the pulse component is removed by the low-pass filter, and only the disturbance light component enters the polarity inverting amplifier, and after its polarity is inverted. , To the connection point via the resistor 2.
そして、この接続点において両電流は、加算され外乱光
成分が相殺されるので、パルス成分のみが積分器に流
れ、直流信号に変換される。Then, at this connection point, both currents are added and the disturbance light component is canceled out, so that only the pulse component flows into the integrator and is converted into a DC signal.
実施例 この発明の一実施例について説明するが、同一図面符号
は、その名称も機能も同一である。Embodiments One embodiment of the present invention will be described, but the same reference numerals have the same names and functions.
パルス発生器１は、分配器２を介して発光素子３に接続
されている。このパルス発生器１は、外乱光４の周波数
の10〜20倍の高周波、例えば、2,000Hzのパルスを発生
させる。The pulse generator 1 is connected to the light emitting element 3 via the distributor 2. The pulse generator 1 generates a pulse having a high frequency of 10 to 20 times the frequency of the ambient light 4, for example, 2,000 Hz.
分配器２は、各発光素子３に接続され、間隔をおいて順
次各発光素子３にパルスを送る。The distributor 2 is connected to each light emitting element 3 and sends a pulse to each light emitting element 3 sequentially at intervals.
発光素子３は、例えば、LEDにより形成され、第１図、
第２図に示す様に、受光素子５と対向して設けられてい
る。The light emitting element 3 is formed of, for example, an LED, and is shown in FIG.
As shown in FIG. 2, it is provided so as to face the light receiving element 5.
この受光素子５は、例えば、フオトトランジスタやフオ
トダイオードで形成されている。The light receiving element 5 is formed of, for example, a phototransistor or a photodiode.
発光素子３と受光素子５は、夫々ウエハカセット６内の
ウエハ溝７の数だけ、例えば25個設けられれるが、透過
形フオトセンサの場合には、前述のように両者３、５を
対向して設け、又、反射形フオトセンサの場合には、第
２図の一点鎖線で示す様に両者3a、5aを間隔をおいて並
列に配設する。The light-emitting element 3 and the light-receiving element 5 are provided in the number of the wafer grooves 7 in the wafer cassette 6, for example, 25 pieces. In the case of a transmissive photosensor, the two elements 3 and 5 face each other as described above. In the case of the reflection type photo sensor, both 3a and 5a are arranged in parallel at an interval as shown by the one-dot chain line in FIG.
各受光素子５は、外乱光補償回路８に接続されている。Each light receiving element 5 is connected to the ambient light compensation circuit 8.
この外乱光補償回路８は、受光素子５に接続する抵抗R1
と、受光素子５にローパスフイルタ９と極性反転アンプ
10とを介して接続された抵抗R2と、抵抗R1、R2の出力端
の接続点Ｃに連結した積分器11とからなる。The disturbance light compensation circuit 8 has a resistor R1 connected to the light receiving element 5.
And a low-pass filter 9 and a polarity inversion amplifier on the light receiving element 5.
A resistor R2 connected via 10 and an integrator 11 connected to a connection point C at the output ends of the resistors R1 and R2.
この抵抗R1と抵抗R2の抵抗値は、等しく形成されてい
る。The resistance values of the resistors R1 and R2 are formed to be equal.
次に、この実施例の作動につき説明するとウエハカセツ
ト６を所定位置に配設し、パルス発生器１から高周波、
例えば、2,000HZのパルスを分配器２に送ると、各発光
素子３は、間隔をおいて順次パルス点灯する。Next, the operation of this embodiment will be described. The wafer cassette 6 is arranged at a predetermined position, and the pulse generator 1 outputs high frequency,
For example, when a pulse of 2,000 HZ is sent to the distributor 2, each light emitting element 3 is sequentially pulsed at intervals.
このパルス点灯された光は、ウエハ溝７にウエハ12が収
納されていると反射されるので、受光素子５に入らない
が、ウエハ溝７にウエハ12が無いと、障害物がないの
で、そのまま受光素子５に入り電流に変換される。This pulsed light does not enter the light receiving element 5 because it is reflected when the wafer 12 is housed in the wafer groove 7, but without the wafer 12 in the wafer groove 7, there is no obstacle. It enters the light receiving element 5 and is converted into a current.
この時受光素子５には、蛍光灯などによる外乱光４が同
時に入るが、この外乱光４は、低周波であり、例えば、
100HZである。At this time, the disturbance light 4 from a fluorescent lamp or the like enters the light receiving element 5 at the same time, and the disturbance light 4 has a low frequency.
It is 100HZ.
この変換された電流は、一方では、そのまま抵抗R1を介
して接続点Ｃに流れ、他方では、ローパスフイルタ（LP
F）９によりパルス成分が除去され、外乱光成分のみが
極性反転アンプ10に−１倍されて、その極性が反転した
後、抵抗R2を介して接続点Ｃに流れる。On the one hand, this converted current flows through the resistor R1 to the connection point C as it is, and on the other hand, the low-pass filter (LP
The pulse component is removed by F) 9, and only the disturbance light component is multiplied by -1 by the polarity inverting amplifier 10 to invert its polarity, and then flows to the connection point C via the resistor R2.
そして、接続点Ｃで両電流は、加算され、外乱光成分が
相殺されてパルス成分だけが抽出される。この抽出され
た信号は、積分器11に入り直流信号に変換され、結果と
して受光量に比例した信号が取り出せる。Then, at the connection point C, the two currents are added, the disturbance light component is canceled out, and only the pulse component is extracted. The extracted signal enters the integrator 11 and is converted into a DC signal, and as a result, a signal proportional to the amount of received light can be taken out.
なお、フオトトランジスタやフオトダイオードでは、発
光素子３が発光していない状態でも光電流が流れるので
（これを暗電流という）、外乱光補償回路８に多くの受
光素子５が接続されていると、前述の暗電流も大きくな
る。In the phototransistor or the photodiode, a photocurrent flows even when the light emitting element 3 is not emitting light (this is called a dark current). Therefore, if many light receiving elements 5 are connected to the ambient light compensation circuit 8, The dark current mentioned above also becomes large.
しかし、この外乱光補償回路８では、常に暗電流が相殺
されるので、この暗電流による誤作動は、完全に防止さ
れる。However, in the disturbance light compensation circuit 8, since the dark current is always canceled out, the malfunction due to the dark current is completely prevented.
発明の効果 この発明は、以上のように受光素子に接続された抵抗R1
と、受光素子にローパスフイルタと極性反転アンプとを
介して接続された抵抗R2と、抵抗R1、R2の出力端の接続
点に連結した積分器とを有するので、受光素子に入つた
パルス光成分と外乱光成分は、電流に変換され、一方で
は、抵抗R1を介して接続点に出力し、他方では、ローパ
スフイルタによりパルス成分が除去され、外乱光成分の
みが極性反転アンプに入り、その極性を反転された上で
抵抗R2を介して持続点に出力し、前記出力と加算され
る。そして外乱光成分は、相殺され、パルス成分だけが
積分器に入り、直流信号に変換される。EFFECTS OF THE INVENTION The present invention relates to the resistor R1 connected to the light receiving element as described above.
And a resistor R2 connected to the light receiving element via a low-pass filter and a polarity inverting amplifier, and an integrator connected to the connection point of the output ends of the resistors R1 and R2, so that the pulsed light component entering the light receiving element And the disturbance light component are converted into a current and output to the connection point via the resistor R1 on the one hand, and the pulse component is removed by the low-pass filter on the other hand, and only the disturbance light component enters the polarity inverting amplifier and its polarity Is inverted and output to the sustain point via the resistor R2, and is added to the output. Then, the ambient light component is canceled out, and only the pulse component enters the integrator and is converted into a DC signal.
このようにパルス成分だけが積分器に入るので結果的に
は、受光量に比例した信号が取り出せる。In this way, only the pulse component enters the integrator, and as a result, a signal proportional to the amount of received light can be taken out.
従つて、外乱光の影響を受けることなく、正確に作動す
るフオトセンサを得ることができる。Therefore, it is possible to obtain a photo sensor that operates accurately without being affected by ambient light.
又、従来例のように積分定数を大きくする必要もないの
で応答性や感度の低下の問題は生じない。Further, unlike the conventional example, there is no need to increase the integration constant, so that there is no problem of deterioration of responsiveness or sensitivity.
第１図は、この発明の実施例を示す図、第２図は、この
発明の使用状態を示す一部断面図である。 １……パルス発生器 ３……発光素子 ５……発光素子 ８……外乱光補償回路 ９……ローパスフイルタ 10……極性反転アンプ 11……積分器 R1、R2……抵抗FIG. 1 is a view showing an embodiment of the present invention, and FIG. 2 is a partial cross-sectional view showing a usage state of the present invention. 1 …… Pulse generator 3 …… Light emitting element 5 …… Light emitting element 8 …… Disturbance light compensation circuit 9 …… Low-pass filter 10 …… Polarity inverting amplifier 11 …… Integrator R1, R2 …… Resistance
Claims (2)
周波数よりも高い周波数でパルス点灯する発光素子と受
光素子とを互いに対向するように配設し、該受光素子の
出力側に、抵抗R1の一端を接続するとともに、同じ受光
素子の出力側に外乱光成分のみを通すローパスフィルタ
と該外乱光成分を逆極性にする極性反転アンプ及び別の
抵抗R2の一端を順次直列に接続し、前記各抵抗R1、R2の
それぞれの他端を接続点に連結し、該接続点で前記各抵
抗R1、R2からの各出力を加算してパルス成分のみを求
め、該パルス成分を積算器に入力して直流信号に変換
し、受光量に比例した信号を取り出すことを特徴とする
フォトセンサの外乱光補償回路。1. A light emitting element and a light receiving element which are connected to a pulse generator and which are pulse-lit at a frequency higher than the frequency of the ambient light are arranged so as to face each other, and an output side of the light receiving element is provided. While connecting one end of the resistor R 1, a low-pass filter that passes only the disturbance light component to the output side of the same light receiving element, a polarity inverting amplifier that reverses the disturbance light component, and one end of another resistor R 2 are serially connected. Connected, the other end of each of the resistors R 1 and R 2 is connected to a connection point, and at the connection point the outputs from the resistors R 1 and R 2 are added to obtain only the pulse component, An ambient light compensation circuit for a photo sensor, wherein a pulse component is input to an integrator, converted into a DC signal, and a signal proportional to the amount of received light is extracted.
波数よりも高い周波数でパルス点灯させる工程と； 該発光素子からのパルス成分と外乱光成分とを受光素子
により受光する工程と； 該受光素子からのパルス成分と外乱光成分とからなる合
成出力を接続点に出力する工程と； 該受光素子からの前記合成出力をローパスフィルタに入
力して外乱光成分のみ取り出し該外乱光成分を極性反転
アンプに入力して逆極性成分にした後前記接続点に出力
する工程と； 前記接続点において、前記合成出力と逆極性成分とを加
算し、パルス成分のみを求める工程と； 該パルス成分を積算器に入力し、受光量に比例した信号
を取り出す工程と； をそなえていることを特徴とするフォトセンサの外乱光
補償方法。2. A step of pulse-lighting a light emitting element at a frequency higher than the frequency of disturbance light by a pulse generator; a step of receiving a pulse component and a disturbance light component from the light emitting element by a light receiving element; Outputting a combined output composed of a pulse component and a disturbance light component from the element to a connection point; inputting the combined output from the light receiving element to a low-pass filter and extracting only the disturbance light component, and reversing the polarity of the disturbance light component A step of inputting to an amplifier to make a reverse polarity component and then outputting it to the connection point; a step of adding the synthesized output and a reverse polarity component at the connection point to obtain only a pulse component; A method of compensating for ambient light of a photosensor, comprising:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10835786A JPH073882B2 (en) | 1986-05-12 | 1986-05-12 | Ambient light compensation method for photo sensor and its circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10835786A JPH073882B2 (en) | 1986-05-12 | 1986-05-12 | Ambient light compensation method for photo sensor and its circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS62264679A JPS62264679A (en) | 1987-11-17 |
| JPH073882B2 true JPH073882B2 (en) | 1995-01-18 |
Family
ID=14482672
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10835786A Expired - Fee Related JPH073882B2 (en) | 1986-05-12 | 1986-05-12 | Ambient light compensation method for photo sensor and its circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH073882B2 (en) |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5286176A (en) * | 1976-01-14 | 1977-07-18 | Matsushita Electric Works Ltd | Circuit for preventing errouneous operation in photoelectric switch |
| JPS61176877A (en) * | 1985-01-31 | 1986-08-08 | Sharp Corp | Object detector |
| JPS61265878A (en) * | 1985-05-20 | 1986-11-25 | Sharp Corp | Optical modulation type detecting device |
-
1986
- 1986-05-12 JP JP10835786A patent/JPH073882B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPS62264679A (en) | 1987-11-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |