JP2529870B2 - Lightwave rangefinder - Google Patents
Lightwave rangefinderInfo
- Publication number
- JP2529870B2 JP2529870B2 JP62273900A JP27390087A JP2529870B2 JP 2529870 B2 JP2529870 B2 JP 2529870B2 JP 62273900 A JP62273900 A JP 62273900A JP 27390087 A JP27390087 A JP 27390087A JP 2529870 B2 JP2529870 B2 JP 2529870B2
- Authority
- JP
- Japan
- Prior art keywords
- circuit
- light
- receiving element
- light receiving
- frequency
- 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
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は、目標に照射する照射光に対応する電気信号
と反射光に対応する電気信号の位相差を測定することに
より目標までの距離を測定する光波距離計に関する。DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention determines the distance to a target by measuring the phase difference between the electric signal corresponding to the irradiation light applied to the target and the electric signal corresponding to the reflected light. The present invention relates to an optical distance meter for measuring.
（従来の技術） 従来、この種の光波距離計として、第５図示のような
構成を有するものが知られている。(Prior Art) Conventionally, as this type of optical distance meter, one having a configuration as shown in FIG. 5 is known.
第５図において、ａはレーザダイオード等の発光源
で、該発光源ａは、周波数ｆの正弦波を出力する発振器
ｂに接続された駆動回路ｃの出力で変調された光波を送
信用光学系ｄを介して目標（図示せず）に対して照射す
るようになっている。ｅは目標から反射してきた光を受
信用光学系ｇを介して受光する例えばアバランシェフォ
トダイオードの受光素子であり、該受光素子ｅの一端
は、該受光素子ｅが最適に動作するようなバイアス電圧
を該受光素子ｅに与えるトランジスタから成るバイアス
回路ｈに接続されると共に該バイアス電圧をローカル周
波数（ｆ−fR）で変調するトランジスタから成る変調回
路ｉに接続され、他端は負荷抵抗ｊに接続され、その一
端は周波数選択特性を有し、目的の周波数成分fRを増幅
する増幅器ｋを介して位相差測定回路ｌに接続されてい
る。In FIG. 5, a is a light emitting source such as a laser diode, and the light emitting source a is an optical system for transmitting a light wave modulated by the output of a drive circuit c connected to an oscillator b that outputs a sine wave of frequency f. The target (not shown) is irradiated via d. e is a light receiving element of, for example, an avalanche photodiode that receives the light reflected from the target through the receiving optical system g, and one end of the light receiving element e has a bias voltage for optimally operating the light receiving element e. Is connected to a bias circuit h formed of a transistor for supplying the light receiving element e to the light receiving element e and a modulation circuit i formed of a transistor for modulating the bias voltage at a local frequency (f−f R ), and the other end is connected to a load resistor j. They are connected, one end of which has a frequency selection characteristic, and are connected to the phase difference measuring circuit 1 through an amplifier k that amplifies a target frequency component f R.
該位相差測定回路ｌの他方の入力端子には、前記発振
器ｂの出力の周波数ｆをfRに分周する分周器ｍが接続さ
れ、該分周器ｍは、発振器ｂの出力信号と分周器ｍ出力
信号を用いて極部発振信号（周波数ｆ−fR）を出力する
周波数変換器ｎに接続され、該周波数変換器ｎの出力は
変調回路ｉに供給される。A frequency divider m for dividing the frequency f of the output of the oscillator b into f R is connected to the other input terminal of the phase difference measuring circuit l, and the frequency divider m outputs an output signal of the oscillator b and It is connected to a frequency converter n which outputs a pole oscillation signal (frequency f−f R ) using the output signal of the frequency divider m, and the output of the frequency converter n is supplied to the modulation circuit i.
以上の構成によれば、受光素子ｅで受光したときの光
波は VREC＝Sin（２πft−ψ） …（１） ここで、ψは発光源ａから出射される光波をVT＝Sin
2πftとしたときの目標までの距離に対応する位相差
で、 但し R:目標までの距離 C:光速 受光素子ｅに接続された負荷抵抗ｊに出力する信号V
APDは VAPD＝VL・VREC ＝COS（２πfR t−φ）＋COS｛２π（2f−fR）ｔ−φ｝
…（３） 但し、VL:周波数変換器ｎの出力信号 この信号VAPD増幅器ｋを経ることにより、周波数fRの
成分VSのみが抽出される。According to the above configuration, the light wave when received by the light receiving element e is V REC = Sin (2πft−ψ) (1) where ψ is the light wave emitted from the light emitting source a V T = Sin
Phase difference corresponding to the distance to the target when 2πft is set, Where R: distance to target C: speed of light V signal output to load resistor j connected to light receiving element e
APD is V APD = V L · V REC = COS (2πf R t−φ) + COS {2π (2f−f R ) t−φ}
(3) However, V L : Output signal of the frequency converter n By passing through this signal V APD amplifier k, only the component V S of the frequency f R is extracted.
VS＝COS（２πfRt−ψ） …（４） このVSと分周器ｍの出力信号VR＝COS2πfRtとの位相
差が位相差測定回路ｌで測定され、この位相差から距離
情報が得られる。V S = COS (2πf R t−ψ) (4) The phase difference between this V S and the output signal V R = COS2πf R t of the frequency divider m is measured by the phase difference measuring circuit l, and from this phase difference Distance information is obtained.
（発明が解決しようとする問題点） 従来の上記した回路によれば、バイアス回路ｈ及び変
調回路ｉはトランジスタのコレクタが出力側であるか
ら、その出力インピーダンスは高インピーダンスであ
り、増幅器ｋはある程度の周波数選択特性しか有しない
から、例えばバイアス回路ｋの出力にノイズが混在する
と、ノイズも信号源として増幅器ｋを通過し、また、受
光素子自体から発生する広帯域のノイズ成分も増幅器ｋ
を通過したしまうことになる。したがって該回路ではS/
N比が制限され、高精度の距離情報が得られにくいとい
う問題があった。(Problems to be Solved by the Invention) According to the above-described conventional circuit, the output impedance of the bias circuit h and the modulation circuit i is high because the collectors of the transistors are on the output side, and the amplifier k is to some extent. Since, for example, noise is mixed in the output of the bias circuit k, the noise also passes through the amplifier k as a signal source and the broadband noise component generated from the light receiving element itself is also amplified by the amplifier k.
Will pass through. Therefore, S /
There is a problem that the N ratio is limited and it is difficult to obtain highly accurate distance information.
本発明は、このような問題を解決することをその目的
とするものである。The object of the present invention is to solve such a problem.
（問題点を解決するための手段） 本発明は、上記の目的を達成するために、発光源から
放射される光を変調する変調器と、該光を目標に照射す
るための送信光学系と、目標で反射された光を集めるた
めの受信光学系と、該受信光学系で集光された光を光電
変換する受光素子と、該受光素子を最適動作させるため
のバイアス回路と、該バイアス回路のバイアス電圧を前
記変調器の変調周波数からその分周周波数を減算した周
波数の電圧で変調する変調回路と、照射光に対応する電
気信号と反射光に対応する電気信号の位相差を測定する
位相差測定回路とを備え、その位相差から目標までの距
離を測定するものにおいて、前記変調回路として低出力
インピーダンスのものを用いると共に、前記受光素子の
出力から前記分周周波数成分を抽出する信号抽出回路を
設け、該信号抽出回路を前記位相差測定回路に接続し、
前記バイアス回路の出力に混在するノイズ，前記受光素
子から発生するノイズ等のノイズに対して前記変調回路
及び受光素子が前記信号抽出回路に並列接続されるよう
にしたことを特徴とする。(Means for Solving the Problems) In order to achieve the above object, the present invention provides a modulator for modulating light emitted from a light emitting source, and a transmission optical system for irradiating the light with a target. A receiving optical system for collecting the light reflected by the target, a light receiving element for photoelectrically converting the light collected by the receiving optical system, a bias circuit for optimally operating the light receiving element, and the bias circuit A modulation circuit for modulating the bias voltage of the modulator with a voltage of a frequency obtained by subtracting the frequency division frequency from the modulation frequency of the modulator, and a unit for measuring the phase difference between the electric signal corresponding to the irradiation light and the electric signal corresponding to the reflection light. A circuit for measuring a distance from a phase difference to a target by using a phase difference measuring circuit, which uses a low output impedance as the modulation circuit and extracts the frequency division frequency component from the output of the light receiving element. Signal extraction circuit is provided, and the signal extraction circuit is connected to the phase difference measurement circuit,
The modulation circuit and the light receiving element are connected in parallel to the signal extracting circuit for noise such as noise mixed in the output of the bias circuit and noise generated from the light receiving element.
（作 用） 変調回路は低出力インピーダンスであるので、ノイズ
に対して該変調回路及び受光素子は信号抽出回路並列接
続されたことになる。したがってバイアス回路の出力及
び受光素子自体にノイズが含まれていた場合、該ノイズ
は信号抽出回路で吸収され、位相差測定回路に入力しな
い。(Operation) Since the modulation circuit has a low output impedance, the modulation circuit and the light receiving element are connected in parallel to the signal extraction circuit against noise. Therefore, when noise is included in the output of the bias circuit and the light receiving element itself, the noise is absorbed by the signal extraction circuit and is not input to the phase difference measurement circuit.
（実施例） 以下本発明の実施例を図面につき説明する。Embodiment An embodiment of the present invention will be described below with reference to the drawings.
第１図において、１は発光源で、該発光源１は駆動回
路２に接続され、該駆動回路２は発振器３に接続されて
いる。発光源１から出射される光波は送信用光学系４を
介して目標（図示せず）を照射するようになっている。
５は目標で反射され受信用光学系６を介して入射する光
波を光電交換する例えばアバランシェフォトダイオード
の受光素子で、その一端はバイアス回路７及び変調回路
８に接続され、該変調回路８には、前記発振器３の出力
周波数ｆをfRに分周する分周器９の出力信号と該発振器
３の出力信号を用いて局部発振信号（周波数ｆ−fR）を
出力する周波数変換器10が接続されている。前記受光素
子５の他端から出力する信号の周波数成分fRはそれを選
択増幅する増幅器11を介して位相差測定回路12の一端子
に入力し、該位相差測定回路12によりその他端子に入力
する分周器９の出力信号との間の位相差が測定されるよ
うになっている。In FIG. 1, reference numeral 1 denotes a light emitting source, the light emitting source 1 is connected to a drive circuit 2, and the drive circuit 2 is connected to an oscillator 3. The light wave emitted from the light emission source 1 irradiates a target (not shown) via the transmission optical system 4.
Reference numeral 5 denotes a light receiving element of, for example, an avalanche photodiode that photoelectrically exchanges the light wave reflected by the target and incident through the receiving optical system 6, one end of which is connected to the bias circuit 7 and the modulation circuit 8, and the modulation circuit 8 includes , A frequency converter 10 for outputting a local oscillation signal (frequency f−f R ) using the output signal of the frequency divider 9 for dividing the output frequency f of the oscillator 3 into f R and the output signal of the oscillator 3. It is connected. The frequency component f R of the signal output from the other end of the light receiving element 5 is input to one terminal of the phase difference measuring circuit 12 via the amplifier 11 that selectively amplifies it, and is input to the other terminal by the phase difference measuring circuit 12. The phase difference with the output signal of the frequency divider 9 is measured.
以上の構成及び作用は、上記した従来のものと特に異
ならない。The above-described structure and operation are not particularly different from those of the above-described conventional one.
本発明によれば、前記変調回路８は、例えば、低出力
インピーダンスのバッファ13が使用されており、受光素
子５の出力回路には、コンデンサ14及びインダクタンス
15から成り、前記周波数成分fRの信号を抽出する信号抽
出回路16が接続され、該信号抽出回路16と受光素子５と
の接続点に出力側が位相差測定回路12に接続された増幅
器11の入力側が接続されている。According to the present invention, the modulation circuit 8 uses, for example, a buffer 13 having a low output impedance, and the output circuit of the light receiving element 5 includes a capacitor 14 and an inductance.
A signal extraction circuit 16 for extracting the signal of the frequency component f R is connected, and the output side of the amplifier 11 is connected to the phase difference measurement circuit 12 at the connection point between the signal extraction circuit 16 and the light receiving element 5. Input side is connected.
本発明の実施例回路において、受光素子５自体のノイ
ズ、太陽光等の外乱光などのノイズ又はバイアス回路７
の出力に含まれるノイズが発生すると、実施例回路はノ
イズに対しては、第２図示のような回路となり、受光素
子５及び変調回路８は信号抽出回路15に並列接続される
ことになる。In the circuit of the embodiment of the present invention, noise of the light receiving element 5 itself, noise such as ambient light such as sunlight, or the bias circuit 7
When the noise included in the output is generated, the circuit of the embodiment becomes a circuit as shown in the second figure with respect to the noise, and the light receiving element 5 and the modulation circuit 8 are connected in parallel to the signal extraction circuit 15.
かくてノイズ信号17は信号抽出回路16で吸収され、測
定に必要な周波数成分fRの信号のみが増幅器11の入力に
現われることになる。Thus, the noise signal 17 is absorbed by the signal extraction circuit 16, and only the signal of the frequency component f R necessary for measurement appears at the input of the amplifier 11.
以上の実施例では、前記変調回路８として低出力イン
ピーダンスのバッファ13が使用されているが、第３図示
のように、トランジスタ18のコレクタに変成器19を接続
し、その２次側を受光素子５に接続して低出力インピー
ダンスとしたり、あるいは、第４図示のように、トラン
ジスタ18のエミッタフォロワの回路構成として低出力イ
ンピーダンスとしてもよい。In the above embodiment, the buffer 13 having a low output impedance is used as the modulation circuit 8. However, as shown in FIG. 3, the transformer 19 is connected to the collector of the transistor 18, and the secondary side thereof is the light receiving element. The output follower may be connected to No. 5 to have a low output impedance, or as shown in FIG. 4, the emitter follower of the transistor 18 may have a low output impedance as a circuit configuration.
（発明の効果） 以上説明したように、本発明によれば、受光素子自体
から発生するノイズ、バイアス回路に含まれるノイズ等
を無くしS/N比を向上し、高精度の距離情報が得られる
効果を有する。(Effects of the Invention) As described above, according to the present invention, noise generated from the light receiving element itself, noise included in the bias circuit, etc. is eliminated, the S / N ratio is improved, and highly accurate distance information can be obtained. Have an effect.
第１図は本発明の１実施例のブロック図、第２図はその
ノイズに対する回路図、第３図及び第４図はその変調回
路の他の例の回路図、第５図は従来例のブロック図であ
る。 １……発光源、３……発振器 ４……送信光学系、５……受光素子 ６……受信光学系、７……バイアス回路 ８……変調回路、９……分周器 12……位相差測定回路、16……信号抽出回路 17……ノイズ信号FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a circuit diagram for the noise, FIGS. 3 and 4 are circuit diagrams of other examples of the modulation circuit, and FIG. 5 is a conventional example. It is a block diagram. 1 ... Emission source, 3 ... Oscillator, 4 ... Transmission optical system, 5 ... Light receiving element, 6 ... Reception optical system, 7 ... Bias circuit, 8 ... Modulation circuit, 9 ... Divider, 12 ... Phase difference measurement circuit, 16 …… Signal extraction circuit 17 …… Noise signal
Claims (1)
と、該光を目標に照射するための送信光学系と、目標で
反射された光を集めるための受信光学系と、該受信光学
系で集光された光を光電変換する受光素子と、該受光素
子を最適動作させるためのバイアス回路と、該バイアス
回路のバイアス電圧を前記変調器の変調周波数からその
分周周波数を減算した周波数の電圧で変調する変調回路
と、照射光に対応する電気信号と反射光に対応する電気
信号の位相差を測定する位相差測定回路とを備え、その
位相差から目標までの距離を測定するものにおいて、前
記変調回路として低出力インピーダンスのものを用いる
と共に、前記受光素子の出力から前記分周周波数成分を
抽出する信号抽出回路を設け、該信号抽出回路を前記位
相差測定回路に接続し、前記バイアス回路の出力に混在
するノイズ，前記受光素子から発生するノイズ等のノイ
ズに対して前記変調回路及び受光素子が前記信号抽出回
路に並列接続されるようにしたことを特徴とする光波距
離計。1. A modulator for modulating light emitted from a light emitting source, a transmission optical system for irradiating the target with the light, a reception optical system for collecting light reflected by the target, and the reception. A light receiving element for photoelectrically converting the light collected by the optical system, a bias circuit for optimally operating the light receiving element, and a bias voltage of the bias circuit is obtained by subtracting the frequency division frequency from the modulation frequency of the modulator. A modulation circuit that modulates with a voltage of frequency and a phase difference measurement circuit that measures the phase difference between the electric signal corresponding to the irradiation light and the electric signal corresponding to the reflected light are provided, and the distance from the phase difference to the target is measured. In this case, a low output impedance modulation circuit is used, and a signal extraction circuit for extracting the divided frequency component from the output of the light receiving element is provided, and the signal extraction circuit is connected to the phase difference measurement circuit. However, the modulation circuit and the light receiving element are connected in parallel to the signal extracting circuit for noise such as noise mixed in the output of the bias circuit and noise generated from the light receiving element. Rangefinder.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62273900A JP2529870B2 (en) | 1987-10-29 | 1987-10-29 | Lightwave rangefinder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62273900A JP2529870B2 (en) | 1987-10-29 | 1987-10-29 | Lightwave rangefinder |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01114777A JPH01114777A (en) | 1989-05-08 |
| JP2529870B2 true JP2529870B2 (en) | 1996-09-04 |
Family
ID=17534137
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62273900A Expired - Fee Related JP2529870B2 (en) | 1987-10-29 | 1987-10-29 | Lightwave rangefinder |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2529870B2 (en) |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4113381A (en) * | 1976-11-18 | 1978-09-12 | Hewlett-Packard Company | Surveying instrument and method |
| JPS60260872A (en) * | 1984-06-07 | 1985-12-24 | Mitsubishi Electric Corp | Distance measuring instrument |
-
1987
- 1987-10-29 JP JP62273900A patent/JP2529870B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01114777A (en) | 1989-05-08 |
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