JP2942046B2 - Optical ranging sensor - Google Patents
Optical ranging sensorInfo
- Publication number
- JP2942046B2 JP2942046B2 JP34489291A JP34489291A JP2942046B2 JP 2942046 B2 JP2942046 B2 JP 2942046B2 JP 34489291 A JP34489291 A JP 34489291A JP 34489291 A JP34489291 A JP 34489291A JP 2942046 B2 JP2942046 B2 JP 2942046B2
- Authority
- JP
- Japan
- Prior art keywords
- light
- psd
- amount
- circuit
- distance measuring
- 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
Landscapes
- Length Measuring Devices By Optical Means (AREA)
- Measurement Of Optical Distance (AREA)
- Photo Coupler, Interrupter, Optical-To-Optical Conversion Devices (AREA)
- Optical Radar Systems And Details Thereof (AREA)
Description
【0001】[0001]
【産業上の利用分野】本発明は、PSD等の光学的測距
センサーに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical distance measuring sensor such as a PSD.
【0002】[0002]
【従来の技術】PSD(Position Sensi
tive Photodetector=半導***置検
出素子)は、ホトダイオード(PD)を応用した光スポ
ツト位置検出用センサーである。2. Description of the Related Art PSD (Position Sensi)
The active Photodetector (semiconductor position detecting element) is a light spot position detecting sensor to which a photodiode (PD) is applied.
【0003】このPSDは、入射する光スポツトの位置
により、取出される信号電流I1とI2のバランスが変化
する。図2に、PSDを用いた測距センサーの検出原理
図を示す。In this PSD, the balance between the extracted signal currents I 1 and I 2 changes depending on the position of the incident light spot. FIG. 2 shows a detection principle diagram of a distance measuring sensor using a PSD.
【0004】図2に示すように、赤外発光ダイオード1
(LED)にて発光された光は、レンズ2を通して反射
物(一例として人物)3にて反射し、レンズ4を通して
PSD5に入射する。この反射光MがPSD5に入射す
る位置(光のスポツト位置)は、人物3とセンサーとの
距離Dによつて変化し、反射物3が遠くなると(Dが長
くなると)、反射光M1は図2中の点線のようになり、
PSD5に入射する光のスポツト位置も変化する。PS
D5に入射する光のスポツト位置が変化すると、これに
応じてPSD5の両端から取出される信号電流I1とI2
のバランスが変化する。[0004] As shown in FIG.
The light emitted from the (LED) is reflected by a reflector (for example, a person) 3 through a lens 2 and is incident on a PSD 5 through a lens 4. The position where the reflected light M is incident on the PSD 5 (spot position of the light) changes depending on the distance D between the person 3 and the sensor, and when the reflection object 3 is farther (when D becomes longer), the reflected light M1 is shown in FIG. It looks like the dotted line in 2,
The spot position of the light incident on the PSD 5 also changes. PS
When Supotsuto position of light changes incident to D5, the signal current I 1 and I 2 to be taken out from both ends of PSD5 accordingly
The balance changes.
【0005】この信号電流I1とI2のバランスを信号処
理回路にて検出することにより、反射物3とセンサーの
距離を検出することができ、PSD5を用いた測距セン
サーとして使用することができる。図5にPSD5を用
いた従来の測距センサーの機能ブロックを示す。図5に
おいて、8は信号処理回路部、9はLED駆動回路部で
ある。By detecting the balance between the signal currents I 1 and I 2 by a signal processing circuit, the distance between the reflector 3 and the sensor can be detected, and the sensor can be used as a distance measuring sensor using the PSD 5. it can. FIG. 5 shows functional blocks of a conventional distance measuring sensor using the PSD 5. As shown in FIG. In FIG. 5, reference numeral 8 denotes a signal processing circuit, and 9 denotes an LED drive circuit.
【0006】ここで、PSDの動作原理を図4に基づい
て説明する。PSD5は、図4の(A)に示すように、
シリコンチップの表面にp-層、裏面にn +層、そしてそ
の中間にあるI層の3層から構成され、PSD5の表面
に光スポットφを照射したとき、生成された電荷(キャ
リアー)は抵抗層(p-層)で光の入射位置と取り出し
電極A,Bまでの距離に逆比例して分割され、各々の電
極A,Bから電流I1,I2として取り出される。Here, the principle of operation of the PSD will be described with reference to FIG. PSD5 is, as shown in FIG.
The silicon chip is composed of a p - layer on the front surface, an n + layer on the back surface, and an I layer in the middle, and when the surface of the PSD 5 is irradiated with a light spot φ, the generated charges (carriers) are resistive. In the layer (p - layer), the light is divided in inverse proportion to the incident position of light and the distance to the extraction electrodes A and B, and the light is extracted as currents I 1 and I 2 from the electrodes A and B, respectively.
【0007】今、図4の(A)のように、光電流I0、
電極A,Bの中点から光入射位置P点までの距離をx、
入射位置P点から電極Aまでの抵抗値をR1、入射位置
P点から電極Bまでの抵抗値をR2、電極A,B間の距
離をL、電極A,B間の抵抗値をRT、電極A,Bから
取り出される電流をそれぞれI1,I2とすると、電流I
1,I2は以下の(1)(2)式で表される。Now, as shown in FIG. 4A, the photocurrent I 0 ,
The distance from the midpoint of the electrodes A and B to the light incident point P is x,
The resistance from the incident point P to the electrode A is R 1 , the resistance from the incident point P to the electrode B is R 2 , the distance between the electrodes A and B is L, and the resistance between the electrodes A and B is R. Assuming that the currents taken from T and electrodes A and B are I 1 and I 2 , respectively, the current I
1 and I 2 are represented by the following equations (1) and (2).
【0008】[0008]
【数1】 (Equation 1)
【0009】表面抵抗層(p-層)の比抵抗Riの分布が
図4の(B)のように一様であるので、抵抗R1,R2は
入射位置P点から電極A,Bまでの距離に比例し、次式
で表される。Since the distribution of the specific resistance R i of the surface resistance layer (p − layer) is uniform as shown in FIG. 4B, the resistances R 1 and R 2 are changed from the incident point P to the electrodes A and B. It is proportional to the distance to and is expressed by the following equation.
【0010】[0010]
【数2】 (Equation 2)
【0011】これを(1)(2)式に代入すると、電極
A,Bから取り出される電流I1,I2は次式となる。When this is substituted into the equations (1) and (2), the currents I 1 and I 2 extracted from the electrodes A and B are as follows.
【0012】[0012]
【数3】 (Equation 3)
【0013】ここで、電流I1,I2の和と差の比をとる
と次式となる。Here, the ratio of the sum and difference of the currents I 1 and I 2 is given by the following equation.
【0014】[0014]
【数4】 (Equation 4)
【0015】このように、受光素子としてPSDを用い
ると、直接位置情報を出力として得られる。As described above, when the PSD is used as the light receiving element, the position information can be directly obtained as an output.
【0016】このPSD5の信号電流I1とI2を処理す
る信号処理回路8の一例を図6に示す。図6において、
R1〜R7は抵抗、P1〜P5は増幅器を示す。PSD5
の信号電流I1,I2は、電流電圧変換回路部11にて、
電圧V01,V02に変換する。V01はV01=R1×I1、V
02はV02=R1×I2となる。次に、減算回路部12にて
V02とV01の引算を行い、I2−I1に対応した出力電圧
VOAを得る。V0Aは次式で表わされる。FIG. 6 shows an example of the signal processing circuit 8 for processing the signal currents I 1 and I 2 of the PSD 5. In FIG.
R1~R7 resistance, P 1 to P 5 denotes an amplifier. PSD5
The signal currents I 1 and I 2 of
The signals are converted into voltages V 01 and V 02 . V 01 is V 01 = R 1 × I 1 , V
02 is V 02 = R 1 × I 2 . Next, the subtraction of V 02 and V 01 at subtraction circuit 12 to obtain an output voltage V OA corresponding to I 2 -I 1. V 0A is represented by the following equation.
【0017】[0017]
【数5】 (Equation 5)
【0018】また、加算回路部13にて、V01とV02の
足し算を行う。図6において、V03は次式で表わされ
る。[0018] In addition, at the adder circuit unit 13, performs the addition of V 01 and V 02. In FIG. 6, V 03 is represented by the following equation.
【0019】[0019]
【数6】 (Equation 6)
【0020】そして、I1+I2に対応した出力VOBを得
ることができる。V0Bは次式で表わされる。Then, an output V OB corresponding to I 1 + I 2 can be obtained. V 0B is represented by the following equation.
【0021】[0021]
【数7】 (Equation 7)
【0022】このVOAとVOBをマイコン等で演算処理す
ることにより、VOA/VOBを求める。 V0A/V0Bは次
式で表わされる。The V OA and V OB are processed by a microcomputer or the like to obtain V OA / V OB . V 0A / V 0B is represented by the following equation.
【0023】[0023]
【数8】 (Equation 8)
【0024】したがつて、(I2−I1)/(I1+I2)
は、上述の如く、PSD5に入射する光の位置に対応し
ており、(I2−I1)/(I1+I2)により、PSD5
に入射する光のスポツト位置がわかる。Therefore, (I 2 −I 1 ) / (I 1 + I 2 )
Corresponds to the position of the light incident on the PSD 5 as described above, and is expressed by (I 2 −I 1 ) / (I 1 + I 2 ).
The position of the spot of the light incident on the spot is known.
【0025】PSD5に入射する光のスポツト位置がわ
かると、前述のように、センサーと反射物3との距離が
わかる。When the spot position of the light incident on the PSD 5 is known, the distance between the sensor and the reflector 3 is known as described above.
【0026】このようにして、PSD5の信号電流I1
とI2を信号処理回路8にて処理することにより、セン
サーと反射物3の距離を検出することができる。As described above, the signal current I 1 of the PSD 5 is obtained.
And I 2 are processed by the signal processing circuit 8, so that the distance between the sensor and the reflector 3 can be detected.
【0027】また、PSD5の他の信号処理回路8の例
を図7に示す。図7の回路において、15は対数変換回
路部、16は差動増幅回路部、17,18はlogダイ
オードで、その出力V01,V02は次式で表される。な
お、kはボルツマン定数、Tは絶対温度(°K)、qは
電子の電荷量である。FIG. 7 shows an example of another signal processing circuit 8 of the PSD 5. In the circuit of FIG. 7, 15 is a logarithmic conversion circuit section, 16 is a differential amplifier circuit section, 17 and 18 are log diodes, and outputs V 01 and V 02 are represented by the following equations. Here, k is the Boltzmann constant, T is the absolute temperature (° K), and q is the amount of electron charge.
【0028】[0028]
【数9】 (Equation 9)
【0029】そして、増幅回路部16内からの出力V0
は次式で表わされる。The output V 0 from inside the amplifier circuit section 16
Is represented by the following equation.
【0030】[0030]
【数10】 (Equation 10)
【0031】この回路により、log(I1/I2)に対
応した出力を得ることができる。I1/I2は、前述の如
く、PSD5に入射する光のスポツト位置に対応してお
り、log(I1/I2)により、PSD5に入射する光
のスポツト位置がわかる。PSD5に入射する光のスポ
ツト位置がわかると、前述のように、センサーと反射物
3との距離を検出することができる。With this circuit, an output corresponding to log (I 1 / I 2 ) can be obtained. As described above, I 1 / I 2 corresponds to the spot position of the light incident on the PSD 5 , and the log (I 1 / I 2 ) indicates the spot position of the light incident on the PSD 5 . When the spot position of the light incident on the PSD 5 is known, as described above, the sensor and the reflector
3 can be detected.
【0032】[0032]
【発明が解決しようとする課題】上記従来技術では、図
5の如く、LED1は、駆動回路部9のみにより駆動制
御されているので、発光量の制御は測距物体までの距離
によらず一定であつた。そのため、例えば、図2の如
く、PSD5を使用した場合、遠距離まで測定しようと
すると、受光量を大きくする必要がある。In the above prior art, as shown in FIG. 5, since the LED 1 is driven and controlled only by the drive circuit 9, the control of the light emission amount is constant regardless of the distance to the distance measuring object. It was. Therefore, for example, as shown in FIG. 2, when the PSD 5 is used, it is necessary to increase the amount of received light in order to measure a long distance.
【0033】しかし、そうすると、近距離側でPSD5
の許容光電流(図3)を越えるようになり、測距範囲が
制限されるようになる。However, when doing so, the PSD5 on the short distance side
Above the allowable photocurrent (FIG. 3), and the range of distance measurement is limited.
【0034】なお、図3において(A)はPSD5の等
価回路を示し、(B)は逆バイアスVRでの等価回路を
示す。この回路における許容光電流Iは次式で表わされ
る。[0034] Incidentally, in FIG. 3 (A) shows an equivalent circuit of the PSD 5, (B) shows an equivalent circuit of the reverse bias V R. The allowable photocurrent I in this circuit is represented by the following equation.
【0035】[0035]
【数11】 [Equation 11]
【0036】但し、VDFはダイオードの順方向電圧であ
る。Here, V DF is a forward voltage of the diode.
【0037】本発明は、上記に鑑み、PSDを使用して
も、遠距離までの測定も可能とする測距センサーの提供
を目的とする。In view of the above, it is an object of the present invention to provide a distance measuring sensor which can measure a long distance even if a PSD is used.
【0038】[0038]
【課題を解決するための手段】本発明は、図1に示すよ
うに、PSDの入射光量をモニターし、そのPSD光出
力電流により発光量を制御することにより、遠距離、近
距離の測距範囲を拡大しようとするものである。SUMMARY OF THE INVENTION As shown in FIG. 1, the present invention monitors the amount of light incident on a PSD and controls the amount of light emission based on the output current of the PSD light. Try to expand the range.
【0039】[0039]
【作用】上記課題解決手段において、PSD5の光出力
電流が大きくなれば、発光量を小さくし、PSD5の許
容光電流を越えないようにする。In the above means for solving the problems, when the light output current of the PSD 5 increases, the light emission amount is reduced so as not to exceed the allowable light current of the PSD 5.
【0040】[0040]
【実施例】以下、本発明の一実施例を図1に基づいて説
明する。An embodiment of the present invention will be described below with reference to FIG.
【0041】図1において、1は発光素子としてのLE
D、5は受光部としてのPSD、8は信号処理回路であ
り、これらの構成部品は従来と同一機能であるため、そ
の説明を省略する。In FIG. 1, reference numeral 1 denotes an LE as a light emitting element.
D and 5 are PSDs as light receiving units, and 8 is a signal processing circuit. These components have the same functions as those of the conventional one, and therefore description thereof is omitted.
【0042】そして、本実施例では、PSD5の受光量
を検出する受光量検出回路21が設けられる。この検出
回路21は、PSD5の共通端子、すなわち図1,4に
示すpnダイオードのn側の端子Cに接続され、PSD
5に流れる光電流を検出するものである。In this embodiment, a light receiving amount detecting circuit 21 for detecting the light receiving amount of the PSD 5 is provided. This detection circuit 21 has a common terminal of the PSD 5,
Connected to the n-side terminal C of the pn diode shown
5 is to detect the photocurrent flowing through 5.
【0043】この検出回路21からの信号は、LED1
からの発光量を制御する制御回路22に入力される。制
御回路22では、PSD5の許容光電流を越えないよう
に、LED1の発光量を制御する。すなわち、PSD5
の光出力電流が大きくなれば発光量を小さくし、PSD
5の許容光電流を越えないようにする。The signal from the detection circuit 21 is
Is input to a control circuit 22 for controlling the amount of light emitted from the light source. The control circuit 22 controls the light emission amount of the LED 1 so as not to exceed the allowable photocurrent of the PSD 5. That is, PSD5
If the light output current of the LED increases, the light emission amount decreases and the PSD
The allowable photocurrent of 5 is not exceeded.
【0044】上記構成において、遠距離まで測定すると
きは、発光量を大きくするよう制御する。この場合、反
射物からの受光量は、さほど大きくないため、PSD5
は許容光電流を越えることはない。In the above configuration, when measuring to a long distance, control is performed to increase the light emission amount. In this case, since the amount of light received from the reflecting object is not so large, PSD5
Does not exceed the allowable photocurrent.
【0045】また、近距離を測定する場合、発光量を小
さくして、PSD5の許容光電流を越えないようにす
る。When measuring a short distance, the amount of light emission is reduced so that the allowable photocurrent of the PSD 5 is not exceeded.
【0046】なお、本発明は、上記実施例に限定される
ものではなく、本発明の範囲内で上記実施例に多くの修
正および変更を加え得ることは勿論である。It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that many modifications and changes can be made to the above-described embodiment within the scope of the present invention.
【0047】[0047]
【発明の効果】以上の説明から明らかな通り、本発明に
よると、測定距離に応じて発光部からの発光量を制御し
ているので、近距離のみならず遠距離まで測定できる。As is clear from the description above, according to the present invention, according <br/> to the onset bright, since the controlled amount of light emitted from the light emitting portion in accordance with the measurement distance, long distance not short distance only Can be measured.
【0048】また、受光部として、半導***置検出素子
(PSD)を使用しても、その受光量を検出して、許容
光電流を越えないように発光量を制御しているので、近
距離、遠距離の測定範囲が拡大されるといった優れた効
果がある。この半導***置検出素子の受光量を検出する
とき、共通端子からの出力信号である半導***置検出素
子に流れる光電流に基づいて検出しているので、加算演
算が不要となって受光量検出回路の構成を簡単にでき
る。 Even if a semiconductor position detecting element (PSD) is used as the light receiving section, the light receiving amount is detected and the light emitting amount is controlled so as not to exceed the allowable photocurrent. There is an excellent effect that the measurement range at a long distance is expanded. Detecting the amount of light received by this semiconductor position detecting element
When the semiconductor position detection element which is the output signal from the common terminal
Detection based on the photocurrent flowing through the
Calculation is not required and the configuration of the received light amount detection circuit can be simplified.
You.
【図1】本発明に係る測距センサーの機能ブロツク図FIG. 1 is a functional block diagram of a distance measuring sensor according to the present invention.
【図2】測距センサーの検出原理図FIG. 2 is a diagram showing the principle of detection by a distance measuring sensor.
【図3】(A)はPSDの等価回路図、(B)はPSD
の逆バイアスでの等価回路図3A is an equivalent circuit diagram of a PSD, and FIG. 3B is a PSD.
Equivalent circuit diagram with reverse bias
【図4】(A)はPSDの動作原理図、(B)は表面抵
抗層の比抵抗Riの分布図4A is a diagram illustrating the principle of operation of a PSD, and FIG. 4B is a distribution diagram of a specific resistance R i of a surface resistance layer.
【図5】従来の測距センサーの機能ブロック図FIG. 5 is a functional block diagram of a conventional distance measuring sensor.
【図6】従来のPSDの信号電流I1,I2の信号処理回
路図FIG. 6 is a signal processing circuit diagram of signal currents I 1 and I 2 of a conventional PSD.
【図7】従来のPSDの信号電流I1,I2の別の信号処
理回路図FIG. 7 is another signal processing circuit diagram of signal currents I 1 and I 2 of a conventional PSD.
1 赤外発光ダイオード 2 レンズ 3 反射物 4 レンズ 5 PSD 8 信号処理回路 21 受光量検出回路 22 発光量制御回路 DESCRIPTION OF SYMBOLS 1 Infrared light emitting diode 2 Lens 3 Reflector 4 Lens 5 PSD 8 Signal processing circuit 21 Light reception amount detection circuit 22 Light emission amount control circuit
Claims (1)
反射した光を半導***置検出素子で構成された受光部で
受け、受光した光の受光位置に応じて検出物体までの距
離を測定する光学的測距センサーにおいて、前記受光部
での受光量を前記半導***置検出素子の共通端子からの
出力信号に基づいて検出する受光量検出回路が設けら
れ、該受光量検出回路からの検出結果に基いて、前記半
導***置検出素子の光出力電流が許容光電流を越えない
ように前記発光部からの発光量を制御する制御回路が設
けられたことを特徴とする光学的測距センサー。1. A light from a light emitting unit is applied to a detection object, the reflected light is received by a light receiving unit constituted by a semiconductor position detecting element, and a distance to the detection object is measured according to a light receiving position of the received light. In the optical distance measuring sensor, the amount of light received by the light receiving unit is changed from a common terminal of the semiconductor position detecting element.
A light reception amount detection circuit for detecting based on the output signal is provided, and based on a detection result from the light reception amount detection circuit, the light emitting unit outputs a light output current of the semiconductor position detection element so as not to exceed an allowable photocurrent. An optical distance measuring sensor comprising a control circuit for controlling the amount of light emitted from the optical distance measuring device.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP34489291A JP2942046B2 (en) | 1991-12-26 | 1991-12-26 | Optical ranging sensor |
US07/994,970 US5488468A (en) | 1991-12-26 | 1992-12-22 | Optical distance measuring apparatus having semiconductor position sensitive photodetector |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP34489291A JP2942046B2 (en) | 1991-12-26 | 1991-12-26 | Optical ranging sensor |
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Publication Number | Publication Date |
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JPH05172565A JPH05172565A (en) | 1993-07-09 |
JP2942046B2 true JP2942046B2 (en) | 1999-08-30 |
Family
ID=18372804
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JP34489291A Expired - Fee Related JP2942046B2 (en) | 1991-12-26 | 1991-12-26 | Optical ranging sensor |
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DE4312186C2 (en) * | 1993-04-14 | 1995-04-06 | Sick Optik Elektronik Erwin | Methods and devices for determining objects present in a surveillance area and / or for determining their position |
JP2016218064A (en) * | 2015-05-19 | 2016-12-22 | 日本精工株式会社 | Proximity sensor |
JP6771704B2 (en) * | 2018-08-01 | 2020-10-21 | 三菱電機株式会社 | Laser radar device |
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