JPH088470Y2 - Lightwave rangefinder - Google Patents
Lightwave rangefinderInfo
- Publication number
- JPH088470Y2 JPH088470Y2 JP8442889U JP8442889U JPH088470Y2 JP H088470 Y2 JPH088470 Y2 JP H088470Y2 JP 8442889 U JP8442889 U JP 8442889U JP 8442889 U JP8442889 U JP 8442889U JP H088470 Y2 JPH088470 Y2 JP H088470Y2
- Authority
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- Japan
- Prior art keywords
- frequency
- light
- bias
- signal
- receiving element
- Prior art date
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- Expired - Lifetime
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Description
【考案の詳細な説明】 〔産業上の利用分野〕 本考案は複数の強度変調周波数を用いる光波測距儀に
関するものである。DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a lightwave rangefinder using a plurality of intensity modulation frequencies.
光波測距儀では一般に変調周波数fTにて強度変調され
た送信光が、測定点におかれた反射鏡で反射され、位相
差φの遅れをもって受光素子に受信される。この位相差
φの遅れは測定距離と比例の関係にあり、複数の強度変
調周波数fTを併用することにより最大測定距離の向上、
高精度化が可能となる。In a light wave range finder, transmitted light whose intensity is generally modulated at a modulation frequency f T is reflected by a reflecting mirror placed at a measurement point and received by a light receiving element with a delay of a phase difference φ. The delay of this phase difference φ is proportional to the measurement distance, and the maximum measurement distance can be improved by using a plurality of intensity modulation frequencies f T together.
Higher accuracy is possible.
受信信号は位相差φの遅れを計測するため、周波数混
合によって位相情報を保存したまま、中間周波数fIFに
変換される。Since the received signal measures the delay of the phase difference φ, it is converted to the intermediate frequency f IF while the phase information is preserved by frequency mixing.
この周波数混合にはバイアス電圧制御によって増倍率
を可変できるアバランシェ・フォト・ダイオード（以下
APDと記す）が使用されている。第２図にAPD伝達特性の
一例を示す。第２図によれば、直流バイアス電圧を増大
する、APDがブレークダウン電圧になる前に増倍率が急
激に上昇する。またバイアス電圧に局部発振周波数fRを
重畳することによりAPDは周波数混合作用を持ち、APD出
力電流からは｜fT−fR｜となる中間周波数fIFが得られ
る。For this frequency mixing, the avalanche photo diode (hereinafter referred to as the “avalanche photodiode” whose gain can be changed by controlling the bias voltage
APD) is used. FIG. 2 shows an example of APD transfer characteristics. According to FIG. 2, the DC bias voltage is increased, and the gain is sharply increased before the APD reaches the breakdown voltage. Also, by superimposing the local oscillation frequency f R on the bias voltage, the APD has a frequency mixing action, and the intermediate frequency f IF that is | f T −f R | is obtained from the APD output current.
従来、APDは上述のように、光電変換・増倍作用・周
波数混合作用の３機能を常時受け持っていた。Conventionally, the APD has always been responsible for the three functions of photoelectric conversion, multiplication, and frequency mixing, as mentioned above.
しかしながら、従来の技術に於いては、APDは常に周
波数混合作用を行うため増倍率と周波数混合効率を分離
することは容易ではない。そのためAPD動作点の決定が
困難であり、光波測距儀個々の最大測定距離や精度のば
らつきの原因となっていた。However, in the conventional technique, since the APD always performs the frequency mixing action, it is not easy to separate the multiplication factor and the frequency mixing efficiency. For this reason, it is difficult to determine the APD operating point, which causes variations in the maximum measuring distance and accuracy of each optical rangefinder.
上記問題点の解決の為に本考案は、複数の異なった強
度変調周波数にて強度変調された送信光を時間を異なら
せて出射する光源手段（１、２、３、４、５）と、 受信信号を直流バイアス手段からの直流バイアスに応
じて増倍する作用と共に、局部発振周波数信号発生手段
からの局部発振周波数信号を前記受信光に混合して中間
周波数（fIF）にビートダウンする作用を備えた受光素
子によって、測定点に置かれた反射鏡で反射された受信
光を光電変換する受信手段と（６、７、８、９、10、1
1、12、14）と、 前記異なった強度変調周波数の各々について、前記送
信光と前記受信光との位相差を前記ビートダウンした信
号に基づいて求め、これらの位相差から前記測定点まで
の距離を測定する位相比較手段（13、14）と、 を備えた光波測距儀において、 前記複数の異なった強度変調周波数のうち最低周波数
を（fT４）を前記中間周波数と（fIF）と一致させる（f
IF＝FT４）と共に、 前記受信手段には、前記送信光の強度変調周波数が前
記最低周波数のときは、前記受光素子に直流バイアスの
みを印加し、前記送信光の強度変調周波数が前記最低周
波数以外のときは、前記受光素子に前記直流バイアスと
共に前記局部発振周波数信号を印加する制御手段（９、
14）、 をさらに設けたことを特徴とする光波測距儀。In order to solve the above problems, the present invention provides light source means (1, 2, 3, 4, 5) for emitting transmission light intensity-modulated at a plurality of different intensity modulation frequencies at different times, The function of multiplying the received signal according to the DC bias from the DC bias means, and the function of mixing the local oscillation frequency signal from the local oscillation frequency signal generation means with the received light to beat down to the intermediate frequency (f IF ). And a receiving means (6, 7, 8, 9, 10, 1 for photoelectrically converting received light reflected by a reflecting mirror placed at a measurement point by a light receiving element including
1, 12, 14), for each of the different intensity modulation frequencies, the phase difference between the transmitted light and the received light is determined based on the beat-down signal, from these phase differences to the measurement point. In a lightwave rangefinder equipped with phase comparison means (13, 14) for measuring distance, the lowest frequency (f T 4) of the plurality of different intensity modulation frequencies and the intermediate frequency (f IF ) Matches (f
IF = F T 4), the receiving means applies only a DC bias to the light receiving element when the intensity modulation frequency of the transmission light is the lowest frequency, and the intensity modulation frequency of the transmission light is the lowest frequency. When the frequency is other than the frequency, a control means (9, for applying the local oscillation frequency signal to the light receiving element together with the DC bias).
14), An optical wave rangefinder further comprising:
本考案に於いては、変調周波数fTが最低周波数のとき
は、直流バイアスのみを印加し、APDには増倍作用だけ
を受けもたす。In the present invention, when the modulation frequency f T is the lowest frequency, only the DC bias is applied, and the APD receives only the multiplication effect.
従って、APDの増倍率のみを測定・調整することがで
き、APDの動作点を正しく設定しうる。また変調周波数f
Tが中間周波数とは異なるときは、APDバイアス電圧には
局部発振周波数fRを重畳し、周波数混合作用を行わせる
ことにより、前記設定した増倍率を固定したままで周波
数混合効率を測定・調整することができる。Therefore, only the multiplication factor of the APD can be measured and adjusted, and the operating point of the APD can be set correctly. Also, the modulation frequency f
When T is different from the intermediate frequency, the local oscillation frequency f R is superimposed on the APD bias voltage and the frequency mixing action is performed to measure and adjust the frequency mixing efficiency with the set multiplication factor fixed. can do.
このように変調周波数fTを中間周波数と一致させるこ
とにより、従来と同様の回路構成でAPDの増倍率、周波
数混合効率を性格に設定することができ、APDに起因す
る光波測距儀の最大測定距離や精度のばらつきをなくす
ることができる。By matching the modulation frequency f T with the intermediate frequency in this way, it is possible to set the multiplication factor and frequency mixing efficiency of the APD with the same circuit configuration as the conventional one, and the maximum of the optical rangefinder due to APD can be set. It is possible to eliminate variations in measurement distance and accuracy.
以下本考案の一実施例について説明する。 An embodiment of the present invention will be described below.
第１図に４波の変調周波数を使用する光波測距儀の１
例を示す。基準発信器１の出力信号の周波数をfT１とす
ると、FT発生回路（分周回路）２は周波数fT１を1/1、1
/8、1/200、1/5000分周することにより、それぞれf
T１、fT２、fT３、fT４なる変調周波数を持った変調信
号を発生する。このfT１〜fT４の変調周波数のうち最低
変調周波数fT４を中間周波数fIFと等しくする。マイク
ロコンピュータ14は使用周波数fT１〜fT４のうち１周波
数のみを決定するために２ビットの制御信号FSe１を出
力する。周波数選択回路３に入力された変調周波数fT１
〜fT４の変調信号は制御信号FSe１にてそのうちの１周
波数の信号のみ選択され、駆動回路４に送られる。その
結果、発光素子５は上記のように周波数選択回路３にて
選択された変調周波数で強度変調されて発光する。Fig. 1 shows an example of a lightwave rangefinder that uses four modulation frequencies.
Here is an example: Assuming that the frequency of the output signal of the reference oscillator 1 is f T 1, the FT generation circuit (frequency dividing circuit) 2 changes the frequency f T 1 to 1/1, 1
By dividing by / 8, 1/200, and 1/5000, f
A modulation signal having a modulation frequency of T 1, f T 2, f T 3, f T 4 is generated. The lowest modulation frequency f T 4 of the modulation frequency of the f T 1~f T 4 is equal to the intermediate frequency f IF. The microcomputer 14 outputs a control signal F Se 1 of 2 bits to determine only one frequency among the operating frequency f T 1~f T 4. Modulation frequency f T 1 input to the frequency selection circuit 3
As for the modulated signals of up to f T 4, only the signal of one frequency is selected by the control signal F Se 1 and sent to the drive circuit 4. As a result, the light emitting element 5 emits light after being intensity-modulated at the modulation frequency selected by the frequency selection circuit 3 as described above.
このように、発光素子５の発光により得られる送信光
は測定点に置かれた不図示の反射鏡で反射され、受光素
子（APD）６へ入射される。受光素子６に接続された直
流バイアス回路７は、受光素子６の増倍率を決定する直
流バイアス電圧を発生する。In this way, the transmitted light obtained by the light emission of the light emitting element 5 is reflected by the reflecting mirror (not shown) placed at the measurement point and is incident on the light receiving element (APD) 6. The DC bias circuit 7 connected to the light receiving element 6 generates a DC bias voltage that determines the multiplication factor of the light receiving element 6.
局部発振信号発生回路８はPLLで構成される発信回路
であり、FT発生回路２の変調周波数fT４の変調信号を入
力し、変調周波数fT１〜fT３から中間周波数fIF（周波
数fT４に等しい）だけずれた局部発振周波数fR１〜fR３
を発生する。マイクロコンピュータ14から出力されFSe
１信号は周波数選択回路９にも入力されており、周波数
選択回路３が変調周波数fT４を選択した場合には、周波
数選択回路９は何の出力信号も発生せず、受光素子６に
は直流バイアス回路７の直流バイアス電圧のみが印加さ
れる。The local oscillation signal generation circuit 8 is a transmission circuit composed of a PLL, receives the modulation signal of the modulation frequency f T 4 of the FT generation circuit 2, and outputs from the modulation frequencies f T 1 to f T 3 to the intermediate frequency f IF (frequency local oscillation frequencies f R 1 to f R 3 deviated by (equal to f T 4)
Occurs. Output from microcomputer 14 F Se
One signal is also input to the frequency selection circuit 9, and when the frequency selection circuit 3 selects the modulation frequency f T 4, the frequency selection circuit 9 does not generate any output signal and the light receiving element 6 receives the signal. Only the DC bias voltage of the DC bias circuit 7 is applied.
マイクロコンピュータ14から出力されるFSe１信号に
より周波数選択回路３が変調周波数fT１〜fT３を選択し
た場合には、上記FSe１信号により周波数選択回路９は
直流バイアス電圧に局部発振周波数fR１〜fR３をさせ
る。従って、受光素子６には直流バイアス電圧に局部発
振信号を重畳したバイアス電圧が印加される。When the frequency selection circuit 3 selects the modulation frequency f T 1 to F T 3 by F Se 1 signal outputted from the microcomputer 14, the frequency selection circuit through the F Se 1 signal 9 local oscillator to a DC bias voltage make the frequency f R 1~f R 3. Therefore, a bias voltage in which the local oscillation signal is superimposed on the DC bias voltage is applied to the light receiving element 6.
以上の周波数構成の場合、変調周波数がfT４ならば、
fT４と中間周波数fIFが等しいため、受光素子６に印加
するバイアス電圧は直流バイアス回路７の直流バイアス
電圧のみでよい。従って受光素子６は光電変換・増倍作
用のみ行うため、バイアス電圧の調整によって増倍率の
設定を正しく行うことができる。In the case of the above frequency configuration, if the modulation frequency is f T 4,
Since the intermediate frequency f IF is equal to f T 4, the bias voltage applied to the light receiving element 6 is only the DC bias voltage of the DC bias circuit 7. Therefore, the light-receiving element 6 only performs photoelectric conversion / multiplication operations, so that the multiplication factor can be correctly set by adjusting the bias voltage.
また、変調周波数がfT１〜fT３の場合、直流バイアス
電圧に局部発振周波数fR１〜fR３をそれぞれ重畳したバ
イアス電圧が印加されるため、受光素子６は光電変換作
用・増倍作用・周波数混合作用を行う。ここで変調周波
数fT１〜fT３が選択された場合と変調周波数fT４が選択
された場合とで、電流−電圧変換回路10に生じたゲイン
差が周波数混合効率である。このゲイン差（周波数混合
効率）は、マイクロコンピュータ14から電流−電圧変換
回路10に入力される制御信号FSe１に応じて電流−電圧
変換回路10の増幅率を切り換えることで補正できる。す
なわち、電流−電圧変換回路10には、あらかじめ測定し
たゲイン差を補正するように異なった抵抗値を選択器に
より選択可能に設けておき、マイクロコンピュータ14の
制御信号FSe１により、前記選択器を制御すればよい。Also, when the modulation frequency is f T 1~f T 3, the bias voltage superimposed respectively the local oscillation frequency f R 1~f R 3 to a DC bias voltage is applied, the light receiving element 6 photoelectric conversion action and increase Doubles and mixes frequencies. Here in the case where when the modulation frequency f T 1~f T 3 is selected as the modulation frequency f T 4 is selected, the current - gain difference caused in the voltage conversion circuit 10 is a frequency mixing efficiency. This gain difference (frequency mixing efficiency) can be corrected by switching the amplification factor of the current-voltage conversion circuit 10 according to the control signal F Se 1 input from the microcomputer 14 to the current-voltage conversion circuit 10. That is, different resistance values are provided in the current-voltage conversion circuit 10 so that different resistance values can be selected by a selector so as to correct the gain difference measured in advance, and the selector is selected by the control signal F Se 1 of the microcomputer 14. Should be controlled.
以上の動作によって変調周波数がfT１〜fT４のいかな
る変調信号の場合でも、電流−電圧変換回路10の出力周
波数は中間周波数fIFの信号となる。この信号は自動利
得制御回路（AGC）11によって増幅され、一定振幅に調
整され（これは主に、目標点までの距離が異なることに
よる振幅の減少を補償する）、波形整形回路12によって
パルスに整形された後、位相比較・計数回路13によって
中間周波数fIFのIFR信号との位相差を測定される。マイ
クロコンピュータ14は位相比較・計数回路13の位相差デ
ータを読み取り、距離換算を行い、表示器15に測定距離
を表示させる。Even if the modulation frequency by the above operation of any modulation signal f T 1~f T 4, the current - the output frequency of the voltage conversion circuit 10 is an intermediate frequency f IF of the signal. This signal is amplified by an automatic gain control circuit (AGC) 11 and adjusted to a constant amplitude (which mainly compensates for the decrease in amplitude due to the different distances to the target point), and the waveform shaping circuit 12 converts it into a pulse. After being shaped, the phase comparison / counter circuit 13 measures the phase difference between the intermediate frequency f IF and the IFR signal. The microcomputer 14 reads the phase difference data of the phase comparison / counting circuit 13, converts the distance, and causes the display 15 to display the measured distance.
以上のように、本考案によれば、APDの増倍率を正し
く測定・調整することができ、APDの動作点を正確に設
定しうるばかりでなく、変調周波数のうち最低周波数を
中間周波数と一致させることにより、局部発振周波数を
１周波数省略することができる。As described above, according to the present invention, the multiplication factor of the APD can be correctly measured and adjusted, the operating point of the APD can be set accurately, and the lowest frequency among the modulation frequencies matches the intermediate frequency. By doing so, one local oscillation frequency can be omitted.
従って光波測距儀個々の最大測定距離や精度のばらつ
きを減少することができる。また、従来と同じ回路構成
で変調周波数を１周波数増すことができるので、小型で
高精度の光波測距儀を構成することができる。Therefore, it is possible to reduce the maximum measurement distance and the variation in accuracy of the individual optical distance measuring devices. Further, since the modulation frequency can be increased by one with the same circuit configuration as the conventional one, it is possible to configure a compact and highly accurate lightwave rangefinder.
第１図は本考案の実施例の電気回路のブロック図、第２
図はAPDの伝達特性の一例を示す図である。 〔主要部分の符号の説明〕 fT１、fT２、fT３、fT４……変調周波数、fIF……中間
周波数、FSe１……制御信号、７……直流バイアス回
路、８……局部発振信号発生回路、９……周波数選択回
路、10……電流−電圧変換回路、14……マイクロコンピ
ュータ。FIG. 1 is a block diagram of an electric circuit according to an embodiment of the present invention, and FIG.
The figure shows an example of the transfer characteristics of the APD. [Description of Signs of Main Parts] f T 1, f T 2, f T 3, f T 4 ... Modulation frequency, f IF ... Intermediate frequency, F Se 1 ... Control signal, 7 ... DC bias circuit, 8 ... Local oscillation signal generation circuit, 9 ... Frequency selection circuit, 10 ... Current-voltage conversion circuit, 14 ... Microcomputer.
Claims (1)
調された送信光を時間を異ならせて出射する光源駆動手
段と、 受信信号を直流バイアス手段からの直流バイアスに応じ
て増倍する作用と共に、局部発信周波数信号発生手段か
らの局部発信周波数信号を前記受信光に混合して中間周
波数にビートダウンする作用を備えた受光素子によっ
て、測定点に置かれた反射鏡で反射された受信光を光電
変換する受信手段と、 前記異なった強度変調周波数の各々について、前記送信
光と前記受信光との位相差を前記ビートダウンした信号
に基づいて求め、これらの位相差から前記測定点までの
距離を測定する位相比較手段と、 を備えた光波測距儀において、 前記複数の異なった強度変調周波数のうちの最低周波数
を前記中間周波数と一致させると共に、 前記受信手段には、前記送信光の強度変調周波数が前記
最低周波数のときは、前記受光素子に直流バイアスのみ
を印加し、前記送信光の強度変調周波数が前記最低周波
数以外のときは、前記受光素子に前記直流バイアスと共
に前記局部発信周波数信号を印加する制御手段、 をさらに設けたことを特徴とする光波測距儀。1. A light source driving means for emitting transmission light intensity-modulated at a plurality of different intensity modulation frequencies at different times, and an operation for multiplying a received signal according to a DC bias from a DC bias means. Along with the received light reflected by the reflecting mirror placed at the measurement point, the light receiving element having the function of mixing the received light with the locally transmitted frequency signal from the locally transmitted frequency signal generating means to beat down to the intermediate frequency. Receiving means for photoelectric conversion, for each of the different intensity modulation frequencies, the phase difference between the transmitted light and the received light is obtained based on the beatdown signal, and from these phase differences to the measurement point In a lightwave rangefinder having a phase comparison unit for measuring a distance, a lightwave rangefinder may be used in which a lowest frequency of the plurality of different intensity modulation frequencies is matched with the intermediate frequency. In the receiving means, when the intensity modulation frequency of the transmitted light is the lowest frequency, only a DC bias is applied to the light receiving element, and when the intensity modulated frequency of the transmitted light is other than the lowest frequency, A light distance measuring instrument, further comprising: a control unit that applies the local oscillation frequency signal together with the DC bias to the light receiving element.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8442889U JPH088470Y2 (en) | 1989-07-18 | 1989-07-18 | Lightwave rangefinder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8442889U JPH088470Y2 (en) | 1989-07-18 | 1989-07-18 | Lightwave rangefinder |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0323384U JPH0323384U (en) | 1991-03-11 |
| JPH088470Y2 true JPH088470Y2 (en) | 1996-03-06 |
Family
ID=31632908
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8442889U Expired - Lifetime JPH088470Y2 (en) | 1989-07-18 | 1989-07-18 | Lightwave rangefinder |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH088470Y2 (en) |
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| JP6353515B2 (en) | 2016-12-26 | 2018-07-04 | 株式会社三共 | Game machine |
-
1989
- 1989-07-18 JP JP8442889U patent/JPH088470Y2/en not_active Expired - Lifetime
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5921516B2 (en) | 2013-11-01 | 2016-05-24 | 日本特殊陶業株式会社 | Manufacturing method of spark plug |
| JP6353515B2 (en) | 2016-12-26 | 2018-07-04 | 株式会社三共 | Game machine |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0323384U (en) | 1991-03-11 |
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