JPH0816604B2 - Photo detector - Google Patents
Photo detectorInfo
- Publication number
- JPH0816604B2 JPH0816604B2 JP2080113A JP8011390A JPH0816604B2 JP H0816604 B2 JPH0816604 B2 JP H0816604B2 JP 2080113 A JP2080113 A JP 2080113A JP 8011390 A JP8011390 A JP 8011390A JP H0816604 B2 JPH0816604 B2 JP H0816604B2
- Authority
- JP
- Japan
- Prior art keywords
- signal
- circuit
- amplifier
- output
- attenuation
- 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
- 230000002238 attenuated effect Effects 0.000 claims description 6
- 230000003287 optical effect Effects 0.000 claims description 2
- 230000003321 amplification Effects 0.000 claims 1
- 238000003199 nucleic acid amplification method Methods 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 7
- 230000007257 malfunction Effects 0.000 description 3
- 229920006395 saturated elastomer Polymers 0.000 description 3
- 239000000872 buffer Substances 0.000 description 2
- 238000013016 damping Methods 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
Landscapes
- Length Measuring Devices By Optical Means (AREA)
- Optical Transform (AREA)
- Photometry And Measurement Of Optical Pulse Characteristics (AREA)
- Geophysics And Detection Of Objects (AREA)
Description
【発明の詳細な説明】 （イ）産業上の利用分野 本発明は、物体の移動状態を光学的に検出する光検出
器に関する。The present invention relates to a photodetector that optically detects a moving state of an object.
（ロ）従来の技術 第２図は従来の光検出器を示す図、第３図ABCDEは第
２図の各部波形を示す波形図である。(B) Conventional Technique FIG. 2 is a diagram showing a conventional photodetector, and FIG. 3 ABCDE is a waveform diagram showing waveforms at respective portions in FIG.
第２図において、駆動回路（１）は、駆動信号（第３
図Ａ）を出力し、発光ダイオード（２）は、該駆動信号
のハイレベル期間に発光する。受光ダイオード（３）
は、発光ダイオード（２）の発光信号を受光する。前段
の増幅器（４）は、受光ダイオード（３）の受光信号を
増幅する。可変抵抗（５）は、増幅器（４）の出力とア
ースとの間に接続され、増幅器（４）の増幅信号のレベ
ルを可変する為に手動調整される。後段の増幅器（６）
は、可変抵抗（５）の可変出力点と接続され、増幅器
（４）の増幅信号の可変出力を増幅する（第３図
（Ｂ）。コンパレータ（７）は、非反転入力（＋）端子
が増幅器（６）の出力と接続され且つ反転入力（−）端
子が基準電源VREFを介してアースされ、増幅器（６）の
増幅信号と基準電源VREFから得られる基準信号とを比較
し、ハイレベル又はローレベルの２値からなる比較信号
を出力する（第３図Ｃ）。In FIG. 2, the drive circuit (1) has a drive signal (third
A) is output, and the light emitting diode (2) emits light during the high level period of the drive signal. Light receiving diode (3)
Receives the light emission signal of the light emitting diode (2). The former amplifier (4) amplifies the light receiving signal of the light receiving diode (3). A variable resistor (5) is connected between the output of the amplifier (4) and ground and is manually adjusted to vary the level of the amplified signal of the amplifier (4). Rear stage amplifier (6)
Is connected to the variable output point of the variable resistor (5) and amplifies the variable output of the amplified signal of the amplifier (4) (FIG. 3 (B). The comparator (7) has a non-inverting input (+) terminal. It is connected to the output of the amplifier (6) and its inverting input (-) terminal is grounded via the reference power supply V REF, and the amplified signal of the amplifier (6) is compared with the reference signal obtained from the reference power supply V REF , A comparison signal composed of binary values of level or low level is output (FIG. 3C).
尚、減衰作用を有する可変抵抗（５）を増幅器の入力
に設けた場合、信号のS/Nが悪化し、反対に可変抵抗
（５）を増幅器の後段に設けた場合、増幅器が飽和した
時の増幅信号を十分に減衰できない等の問題がある。そ
こで、２段の増幅器（４）（６）を設け、且つ、増幅器
（４）（６）の間に可変抵抗（５）を設けることによっ
て、前記問題を解決している。When a variable resistor (5) having a damping action is provided at the input of the amplifier, the S / N of the signal deteriorates, and conversely, when the variable resistor (5) is provided at the subsequent stage of the amplifier, when the amplifier is saturated. There is a problem that the amplified signal of 1 cannot be attenuated sufficiently. Therefore, the above problem is solved by providing two-stage amplifiers (4) and (6) and providing a variable resistor (5) between the amplifiers (4) and (6).
（ハ）発明が解決しようとする課題 しかしながら、可変抵抗（５）が手動で調整される
為、過大電流が受光ダイオード（３）を流れても、増幅
器（４）の増幅信号は瞬時に減衰されることはない。例
えば、何らかの原因によって過大電流が受光ダイドード
（３）を流れた場合、増幅器（４）が飽和し、増幅器
（４）が飽和した時の増幅信号が可変抵抗（５）で十分
に減衰されずに後段の増幅器（６）が増幅される（第３
図Ｄ）。この結果、所定の物体が発光ダイオード（２）
及び受光ダイオード（３）の間を通過するしないに関わ
らず、コンパレータ（７）から期間t0の不要なパルスＰ
を含む誤った比較信号が発生し（第３図Ｅ）、後段のロ
ジック回路等（図示せず）が誤動作してしまう問題点が
あった。(C) Problem to be Solved by the Invention However, since the variable resistor (5) is manually adjusted, the amplified signal of the amplifier (4) is instantaneously attenuated even if an excessive current flows through the light receiving diode (3). There is no such thing. For example, when an excessive current flows through the photo diode (3) for some reason, the amplifier (4) is saturated, and the amplified signal when the amplifier (4) is saturated is not sufficiently attenuated by the variable resistor (5). The subsequent amplifier (6) is amplified (3rd
Figure D). As a result, the predetermined object is the light emitting diode (2).
And the unnecessary pulse P of the period t 0 from the comparator (7) regardless of whether or not it passes between the light receiving diode (3) and
There is a problem in that an erroneous comparison signal including the above is generated (FIG. 3E), and a logic circuit and the like (not shown) in the subsequent stage malfunctions.
そこで、本発明は、過大電流が受光ダイオード（３）
を流れても、コンパレータ（７）から正常な比較信号を
発生できる光検出器を提供することを目的とする。Therefore, according to the present invention, an excessive current is generated in the light receiving diode (3).
It is an object of the present invention to provide a photodetector that can generate a normal comparison signal from the comparator (7) even when the current flows.
（ニ）課題を解決するための手段 本発明は、前記問題点を解決する為に成されたもので
あり、その特徴とするところは、受光素子が駆動回路の
駆動信号に応じて発光した時、受光素子が発光信号を受
光することによって生じた受光信号を増幅する第１の増
幅器と、前記第１の増幅器の増幅信号を減衰する減衰回
路と、前記減衰回路の減衰信号を増幅する第２の増幅器
と、前記第２の増幅器の増幅信号と基準信号とをレベル
比較し、物体が前記発光信号の光路を通過したか否かを
表す信号を出力する比較回路と、前記発光信号の発生期
間だけ発生する前記駆動回路の駆動信号と前記第２の増
幅器の増幅信号とをレベル比較し、減衰制御信号を出力
する論理回路と、前記論理回路の減衰制御信号に応じて
前記減衰回路の減衰度を可変する減衰制御回路と、を備
え、前記受光素子の受光信号のレベルが大となり前記第
２の増幅器の出力が大となった時、前記論理回路の論理
出力に従って前記駆動信号の発生期間以外の前記第２の
増幅器の出力のみを減衰させ、前記比較回路から前記物
体の正常な通過状態を表す出力を得る点である。(D) Means for Solving the Problems The present invention has been made to solve the above problems, and is characterized in that when a light receiving element emits light in response to a drive signal of a drive circuit. A first amplifier for amplifying a light receiving signal generated by the light receiving element receiving a light emitting signal, an attenuating circuit for attenuating the amplified signal of the first amplifier, and a second amplifying the attenuating signal of the attenuating circuit. Circuit for comparing the level of the amplified signal of the second amplifier with the reference signal and outputting a signal indicating whether or not an object has passed the optical path of the light emission signal, and a generation period of the light emission signal. The level of the drive signal of the drive circuit and the amplified signal of the second amplifier, and outputs the attenuation control signal, and the attenuation degree of the attenuation circuit according to the attenuation control signal of the logic circuit. Damping control A circuit, and when the level of the light receiving signal of the light receiving element is high and the output of the second amplifier is high, the second output except the period during which the drive signal is generated according to the logic output of the logic circuit. The point is that only the output of the amplifier is attenuated and the output representing the normal passing state of the object is obtained from the comparison circuit.
（ホ）作用 本発明によれば、駆動回路の駆動信号と第２の増幅器
の増幅信号との比較結果に基づいて減衰回路の減衰度を
制御できる為、過大電流が受光素子を流れ第２の増幅器
の出力が大となった場合でも、論理回路の論理出力に従
って駆動信号の発生期間以外の第２の増幅器の出力のみ
を減衰させ、比較回路から物体の正常な通過状態を表す
信号を出力可能となる。(E) Action According to the present invention, since the attenuation degree of the attenuation circuit can be controlled based on the comparison result of the drive signal of the drive circuit and the amplified signal of the second amplifier, an excessive current flows through the light receiving element. Even when the output of the amplifier becomes large, only the output of the second amplifier is attenuated according to the logic output of the logic circuit except during the generation period of the drive signal, and the signal indicating the normal passing state of the object can be output from the comparison circuit. Becomes
（ヘ）実施例 本発明の詳細を図面に従って具体的に説明する。(F) Example The details of the present invention will be specifically described with reference to the drawings.
第１図は本発明の光検出器を示す図、第３図ABCDFは
第１図の各部波形を示す波形図である。尚、第１図にお
いて、第２図と同一素子には同一符号を付してある。FIG. 1 is a diagram showing the photodetector of the present invention, and FIG. 3 ABCDF is a waveform diagram showing the waveform of each part in FIG. In FIG. 1, the same elements as those in FIG. 2 are designated by the same reference numerals.
第１図において、減衰回路（８）は、前段の増幅器
（４）と後段の増幅器（６）との間に接続され、増幅器
（４）の増幅信号を受光ダイオード（３）の電流量に応
じて減衰させる。例えば、減衰回路（８）としては、複
数の差動増幅器を設け、前段の差動増幅器の一方の差動
トランジスタの出力と後段の差動増幅器の一方の差動ト
ラジスタの入力とを接続し、そして、初段の差動増幅器
の一方の差動トランジスタの入力に減衰制御信号を印加
し、最終段の差動増幅器の一方の差動トランジスタの出
力から減衰信号を得る様にすればよい。また、複数のト
ランジスタの出力路を直列接続することによって可変抵
抗（等価的）を形成し、そして、複数のトランジスタの
入力に減衰制御信号を印加し、複数のトランジスタの所
定の出力から減衰信号を得る様にしてもよい。EXORゲー
ト（９）は、一方の入力に駆動回路（１）の駆動信号
（第３図Ａ）が印加され、且つ、他方の入力に増幅器
（６）の増幅信号（第３図Ｂ又はＤ）がバッファ（10）
を介して印加され、両信号を比較する。減衰制御回路
（11）は、EXORゲート（９）の出力に応じて減衰回路
（８）の減衰度を可変する。例えば、増幅器（４）の増
幅信号（第３図Ｂ）がEXORゲート（９）に印加された場
合、EXORゲート（９）の出力が常時「０」の為、減衰回
路（８）の減衰度が常時低く設定される。これより、コ
ンパレータ（７）から正常な比較信号（第３図Ｆ）が得
られる。また、過大電流が受光ダイオード（３）に流
れ、増幅器（４）の増幅信号（第３図Ｄ）がEXORゲート
（９）に印加された場合、EXORゲート（９）の出力が期
間t0だけ「１」の為、減衰回路（８）の減衰度が期間t0
だけ高く設定される。これより、コンパレータ（７）か
ら期間t0のパルスＰの除去された正常な比較信号（第３
図Ｆ）が得られる。尚、減衰回路（８）、増幅器
（６）、バッファ（10）、EXORゲート（11）、及び減衰
回路（８）で形成されるフィードバックループの信号処
理時間は駆動回路（１）の駆動信号の１周期に比べて非
常に短く設定されており、コンパレータ（７）の比較信
号において期間t0のパルスＰは十分に除去される。In FIG. 1, an attenuator circuit (8) is connected between an amplifier (4) at the front stage and an amplifier (6) at the rear stage, and an amplified signal of the amplifier (4) is output according to the current amount of a light receiving diode (3). To attenuate. For example, as the attenuating circuit (8), a plurality of differential amplifiers are provided, and the output of one differential transistor of the preceding differential amplifier and the input of one differential transistor of the following differential amplifier are connected, Then, the attenuation control signal may be applied to the input of one differential transistor of the first stage differential amplifier, and the attenuation signal may be obtained from the output of one differential transistor of the final stage differential amplifier. A variable resistance (equivalent) is formed by connecting the output paths of a plurality of transistors in series, and an attenuation control signal is applied to the inputs of the plurality of transistors to output an attenuation signal from a predetermined output of the plurality of transistors. You may get it. The EXOR gate (9) has one input to which the drive signal (FIG. 3A) of the drive circuit (1) is applied, and the other input to the amplified signal of the amplifier (6) (FIG. 3B or D). Buffers (10)
Is applied via and the two signals are compared. The attenuation control circuit (11) varies the attenuation degree of the attenuation circuit (8) according to the output of the EXOR gate (9). For example, when the amplified signal of the amplifier (4) (FIG. 3B) is applied to the EXOR gate (9), the output of the EXOR gate (9) is always "0", and therefore the attenuation degree of the attenuation circuit (8). Is always set low. As a result, a normal comparison signal (Fig. 3F) is obtained from the comparator (7). Further, when an excessive current flows through the light receiving diode (3) and the amplified signal (FIG. 3D) of the amplifier (4) is applied to the EXOR gate (9), the output of the EXOR gate (9) is for the period t 0 only. Since it is "1", the attenuation of the attenuation circuit (8) is in the period t 0.
Only set higher. From this, the normal comparison signal (third part) from which the pulse P of the period t 0 is removed from the comparator (7)
Figure F) is obtained. The signal processing time of the feedback loop formed by the attenuation circuit (8), the amplifier (6), the buffer (10), the EXOR gate (11), and the attenuation circuit (8) depends on the drive signal of the drive circuit (1). It is set to be extremely shorter than one cycle, and the pulse P of the period t 0 is sufficiently removed in the comparison signal of the comparator (7).
以上より、過大電流が受光ダイドード（３）を流れた
場合でも、コンパレータ（７）から正常な比較信号が得
られ、後段のロジック回路の誤動作が防止される。From the above, even when an excessive current flows through the light receiving diode (3), a normal comparison signal is obtained from the comparator (7), and malfunction of the logic circuit in the subsequent stage is prevented.
（ト）発明の効果 本発明によれば、過大電流が受光素子を流れた場合で
も、第１の比較回路から正常な比較信号を得られ、後段
のロジック回路の誤動作を防止できる。これより、物体
の通過状態を確実に光検出できる利点が得られる。(G) Effect of the Invention According to the present invention, a normal comparison signal can be obtained from the first comparison circuit even when an excessive current flows through the light receiving element, and malfunction of the logic circuit in the subsequent stage can be prevented. As a result, there is an advantage that the passing state of the object can be surely detected by light.
第１図は本発明回路を示す図、第２図は従来回路を示す
図、第３図は第１図及び第２図の各部波形を示す波形図
である。 （４）（６）……増幅器、（７）……コンパレータ、
（８）……減衰回路、（９）……EXORゲート、（11）…
…減衰制御回路。FIG. 1 is a diagram showing a circuit of the present invention, FIG. 2 is a diagram showing a conventional circuit, and FIG. 3 is a waveform diagram showing waveforms at respective portions in FIGS. 1 and 2. (4) (6) …… Amplifier, (7) …… Comparator,
(8) ... Attenuation circuit, (9) ... EXOR gate, (11) ...
… Attenuation control circuit.
Claims (1)
光した時、受光素子が発光信号を受光することによって
生じた受光信号を増幅する第１の増幅器と、 前記第１の増幅器の増幅信号を減衰する減衰回路と、 前記減衰回路の減衰信号を増幅する第２の増幅器と、 前記第２の増幅器の増幅信号と基準信号とをレベル比較
し、物体が前記発光信号の光路を通過したか否かを表す
信号を出力する比較回路と、 前記発光信号の発生期間だけ発生する前記駆動回路の駆
動信号と前記第２の増幅器の増幅信号とをレベル比較
し、減衰制御信号を出力する論理回路と、 前記論理回路の減衰制御信号に応じて前記減衰回路の減
衰度を可変する減衰制御回路と、を備え、 前記受光素子の受光信号のレベルが大となり前記第２の
増幅器の出力が大となった時、前記論理回路の論理出力
に従って前記駆動信号の発生期間以外の前記第２の増幅
器の出力のみを減衰させ、前記比較回路から前記物体の
正常な通過状態を表す出力を得ることを特徴とする光検
出器。1. A first amplifier for amplifying a light reception signal generated by a light receiving element receiving a light emission signal when the light emitting element emits light in response to a drive signal of a drive circuit, and an amplification of the first amplifier. An attenuator circuit for attenuating a signal, a second amplifier for attenuating an attenuator signal of the attenuator circuit, a level comparison between an amplified signal of the second amplifier and a reference signal, and an object passes through the optical path of the light emission signal. A comparison circuit that outputs a signal indicating whether or not the level of the drive signal of the drive circuit that is generated only during the generation period of the light emission signal and an amplified signal of the second amplifier are compared, and a logic that outputs an attenuation control signal A circuit, and an attenuation control circuit that varies the degree of attenuation of the attenuation circuit according to the attenuation control signal of the logic circuit, the level of the light reception signal of the light receiving element is high, and the output of the second amplifier is high. When According to the logic output of the logic circuit, only the output of the second amplifier except the generation period of the drive signal is attenuated, and an output indicating a normal passing state of the object is obtained from the comparison circuit. vessel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2080113A JPH0816604B2 (en) | 1990-03-28 | 1990-03-28 | Photo detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2080113A JPH0816604B2 (en) | 1990-03-28 | 1990-03-28 | Photo detector |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03277909A JPH03277909A (en) | 1991-12-09 |
| JPH0816604B2 true JPH0816604B2 (en) | 1996-02-21 |
Family
ID=13709134
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2080113A Expired - Fee Related JPH0816604B2 (en) | 1990-03-28 | 1990-03-28 | Photo detector |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0816604B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5877766B2 (en) * | 2012-08-02 | 2016-03-08 | アツミ電氣株式会社 | Beam sensor signal processing circuit |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4650633A (en) * | 1984-07-02 | 1987-03-17 | General Electric Company | Method and apparatus for protection of pump systems |
-
1990
- 1990-03-28 JP JP2080113A patent/JPH0816604B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03277909A (en) | 1991-12-09 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |