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JP5730094B2 - Light wave distance meter - Google Patents

Light wave distance meter Download PDF

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JP5730094B2
JP5730094B2 JP2011070404A JP2011070404A JP5730094B2 JP 5730094 B2 JP5730094 B2 JP 5730094B2 JP 2011070404 A JP2011070404 A JP 2011070404A JP 2011070404 A JP2011070404 A JP 2011070404A JP 5730094 B2 JP5730094 B2 JP 5730094B2
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JP2012202944A (en
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康俊 青木
康俊 青木
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Topcon Corp
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Description

本願発明は、目標反射物までの直線距離を光電的に測定する位相差方式の光波距離計に関する。   The present invention relates to a phase difference type lightwave distance meter that photoelectrically measures a linear distance to a target reflector.

この種の光波距離計では、測距光(または参照光)のみで距離を測定した場合には、発光素子の駆動回路や受光素子の検出回路の温度位相ドリフト、増幅器やコンデンサ等からなる電気回路における位相ドリフト等が測定誤差となって顕れるため、測距光と参照光との位相差から測距値を算出することが一般的である。このために、発光素子から出射した光は、測距光路と参照光路に、シャッターを移動させることによって交互に切り換えられる。しかしながら近年、測距時間の高速化が求められており、光路の切換に時間を要するシャッターを用いない光波距離計が望まれていた。   In this type of lightwave distance meter, when the distance is measured only with distance measuring light (or reference light), the temperature phase drift of the drive circuit of the light emitting element and the detection circuit of the light receiving element, an electric circuit comprising an amplifier, a capacitor, etc. Therefore, it is common to calculate the distance value from the phase difference between the distance measuring light and the reference light. For this reason, the light emitted from the light emitting element is alternately switched by moving the shutter between the distance measuring optical path and the reference optical path. However, in recent years, there has been a demand for speeding up of the distance measurement time, and an optical distance meter that does not use a shutter that requires time for switching the optical path has been desired.

シャッターを省いた光波距離計としては、以下のものが開示されている。特許文献1では、発光素子、受光素子をそれぞれ2つずつ備え、第1の発光素子から出射された光の一方は測距光路を経て第1の受光素子に入射し、他方は参照光路を経て第2の受光素子に入射され、第2の発光素子から出射された光は、参照光として、一方は第1の受光素子に入射し、他方は第2の受光素子に入射するように構成されている。そして、分解能に応じて測距値の各桁を決定するために大きさの異なる周波数(f,f)の変調光を両発光素子から交互に出射することにより、測距光に係る中間周波信号、第1〜第3の参照光に係る各中間周波信号の合わせて4つの中間周波信号を得て、これらの初期位相を求めることにより、測定誤差を補正する工夫がなされている。 The following are disclosed as light wave distance meters without a shutter. In Patent Document 1, two light-emitting elements and two light-receiving elements are provided, and one of the light emitted from the first light-emitting element enters the first light-receiving element via the distance measuring optical path, and the other passes through the reference optical path. Light that is incident on the second light receiving element and emitted from the second light emitting element is configured as reference light, one incident on the first light receiving element and the other incident on the second light receiving element. ing. Then, in order to determine each digit of the distance measurement value in accordance with the resolution, the modulated light having different frequencies (f 1 , f 2 ) is alternately emitted from the two light emitting elements, so that the intermediate of the distance measurement light is obtained. A device for correcting the measurement error is obtained by obtaining four intermediate frequency signals in combination of the frequency signal and each of the intermediate frequency signals related to the first to third reference lights, and obtaining their initial phases.

特許文献2では、周波数の異なる2種類の送光信号(f,f),(f-△f,f-△f)を、2つの発光素子から測距光路及び参照光路へ同時に送出し、2つの受光素子で同時に受光して、測距光路と参照光路を同時に測距することで、両光路における温度位相ドリフトを演算処理部にて計算で打ち消し、測定誤差を補正する工夫がなされている。 In Patent Document 2, the frequency of two different light-sending signals (f 1, f 2), (f 1 - △ f 1, f 2 - △ f 2) and from the two light emitting elements distance measuring optical path and the reference light path , Simultaneously receiving light by two light receiving elements, and simultaneously measuring the distance measuring optical path and the reference optical path, the calculation phase cancels the temperature phase drift in both optical paths and corrects the measurement error. Ingenuity has been made.

特開2001−255369号公報(段落0004〜0010,図1)JP 2001-255369 A (paragraphs 0004 to 0010, FIG. 1) 特開2011-2302号公報(段落0014,0016,図1)Japanese Patent Laying-Open No. 20112302 (paragraphs 0014 and 0016, FIG. 1)

しかし、特許文献1では、シャッターを省くことで測距時間が短縮されたものの、各発光素子や各受光素子等の電気部品による温度位相ドリフトによる誤差が完全には除去されない。   However, in Patent Document 1, although the distance measurement time is shortened by omitting the shutter, errors due to temperature phase drift due to electrical components such as each light emitting element and each light receiving element are not completely removed.

特許文献2では、計算により、上記電気部品による温度位相ドリフトに起因する誤差は低減される。しかし、測距光路と参照光路を同時に測距するため同一周波数の中間周波信号が2つ得られ、これらが同一の受光部(増幅器やコンデンサ等の電気部品からなる電気回路)を使用しないために生じる原因不明な位相ドリフト差が残り、これらは計算で除去されない。   In Patent Document 2, the error due to the temperature phase drift due to the electrical component is reduced by calculation. However, in order to measure the distance optical path and the reference optical path at the same time, two intermediate frequency signals having the same frequency are obtained, and these do not use the same light receiving part (an electric circuit made up of electric parts such as an amplifier and a capacitor). The resulting unknown phase drift differences remain and are not removed in the calculations.

本願発明は、従来の光波距離計にみられる問題点を解決するためになされたものであり、光波距離計に固有な誤差(電気部品等の温度位相ドリフト、受光部を異にすることで生じる原因不明な位相ドリフト)の大幅な低減を可能にした光波距離計を提供することを目的とする。   The present invention was made in order to solve the problems found in the conventional optical distance meter, and is caused by errors inherent in the optical distance meter (temperature phase drift of electrical components, etc., and different light receiving portions). An object of the present invention is to provide an optical rangefinder that can significantly reduce the phase drift of unknown causes.

前記目的を達成するために、請求項1に係る光波距離計においては、周波数発振器より生成された周波数信号を大きさの異なる複数の変調周波数に変調された光として出射する第1の発光素子及び第2の発光素子と、前記両発光素子から出射された光を受光する第1の受光素子及び第2の受光素子と、前記第1の受光素子に接続され、周波数変換器を含む第1の受光部と、前記第2の受光素子に接続され、周波数変換器を含む第2の受光部と、を備え、 前記第1の発光素子及び第2の発光素子は、発光切換手段によって交互に切り換えられて択一的に発光し、 第1の発光素子から出射された光は2つに分けられ、一方は測距光として目標反射物までを往復する測距光路を経て第1の受光素子に入射し、他方は参照光として第1の参照光路を経て第2の受光素子に入射し、第2の発光素子から出射された光は2つに分けられ、一方は参照光として第2の参照光路を経て第2の受光素子に入射し、他方は参照光として第3の参照光路を経て第1の受光素子に入射し、 前記第2の受光部を経た中間周波信号が帰還され、整調用信号としてPLL制御回路に入力され、該PLL制御回路において、前記周波数発振器から比較用に分周された固定周波数信号と前記整調用信号とが位相比較されフィルタ平滑後の電圧で発振された周波数がPLL回路出力信号として再出力され、前記PLL回路出力信号が、前記第1の受光部及び第2の受光部の周波数変換器に入力され、それぞれA/D変換器で測定されてデジタルデータに変換されて、演算処理部において、前記択一的発光により得られた測距信号と参照信号の位相差から目標反射物までの測距値を算出するように構成した。
In order to achieve the above object, in the lightwave distance meter according to claim 1, a first light emitting element that emits a frequency signal generated by a frequency oscillator as light modulated to a plurality of modulation frequencies having different sizes, and A second light-emitting element, a first light-receiving element and a second light-receiving element that receive light emitted from both the light-emitting elements, and a first light-receiving element that is connected to the first light-receiving element and includes a frequency converter A light receiving section and a second light receiving section connected to the second light receiving element and including a frequency converter, wherein the first light emitting element and the second light emitting element are alternately switched by a light emission switching means. The light emitted alternatively from the first light emitting element is divided into two, and one of the lights is sent to the first light receiving element through a distance measuring light path that reciprocates to the target reflector as distance measuring light. Incident, and the other is the first reference optical path as reference light The light incident on the second light receiving element and emitted from the second light emitting element is divided into two parts, one of which enters the second light receiving element via the second reference optical path as the reference light, and the other As a reference light, it enters the first light receiving element through the third reference light path, the intermediate frequency signal passed through the second light receiving unit is fed back, and is input to the PLL control circuit as a pacing signal. The fixed frequency signal frequency-divided for comparison from the frequency oscillator and the pacing signal are phase-compared, and the frequency oscillated by the voltage after filter smoothing is re-output as the PLL circuit output signal, and the PLL circuit output signal Are input to the frequency converters of the first light receiving unit and the second light receiving unit, respectively measured by the A / D converter and converted into digital data, and the arithmetic processing unit performs the selective light emission. Obtained Was constructed from the phase difference 距信 No. and the reference signal to calculate the distance value to a target reflector.

(作用)第1の発光素子を発光させて測距すると、PLL回路出力信号は、各発光素子,各受光素子,各受光部の電気部品等の温度位相ドリフト及び受光部を異にする(電気回路を異にする)ことによって生じる原因不明な位相ドリフト等の全ての位相ドリフトに追随した位相を持つため、第1及び第2の受光部の周波数変換器を介して測距信号の位相ドリフトは略除去され、その後A/D変換器で測定される測距信号の位相ドリフトには極小のドリフト量しか含まれなくなる。一方、第2の発光素子を発光させて測距して、同様に参照信号を測定し、測距信号と参照信号の位相差をとれば、計算により上記の様々な位相ドリフトが低減・除去される。   (Operation) When the first light-emitting element emits light and the distance is measured, the PLL circuit output signal varies in temperature phase drift and light-receiving part of each light-emitting element, each light-receiving element, each light-receiving unit electrical component, etc. The phase drift of the ranging signal via the frequency converters of the first and second light receiving units is as follows. The phase drift of the distance measurement signal that is substantially eliminated and then measured by the A / D converter includes only a minimal drift amount. On the other hand, if the second light emitting element emits light and measures the distance, the reference signal is measured in the same manner, and the phase difference between the distance measurement signal and the reference signal is taken, the above-mentioned various phase drifts are reduced or eliminated by calculation. The

請求項2においては、請求項1に記載の光波距離計において、前記PLL制御回路に、前記PLL回路出力信号及び前記周波数発振器からの固定周波数信号が入力されて低周波信号を出力する設定用ミキサーと、前記演算処理部の指令により、前記設定用ミキサーからの低周波信号又は前記整調用信号のいずれか一方を選択的に該PLL制御回路に出力する信号切換手段が設けられ、前記信号切換手段は、前記光波距離計内部の初期設定時には前記低周波信号が、光波距離計内部の増幅度が決定された後は前記整調用信号が出力されるよう構成した。 2. The setting mixer according to claim 1, wherein the PLL control circuit outputs a low frequency signal when the PLL circuit output signal and a fixed frequency signal from the frequency oscillator are input to the PLL control circuit. When, by a command from the arithmetic processing unit, the signal switching means for outputting selectively the PLL control circuit either the low-frequency signal or the pacing signal is provided from the setting mixer, the signal switching means Is configured such that the low-frequency signal is output at the time of initial setting inside the lightwave distance meter and the pacing signal is output after the amplification degree inside the lightwave distance meter is determined.

(作用)本願発明に係る光波距離計の製造時、初期のPLL制御回路は、各受光部の増幅度が決定されていないため、PLL回路出力信号が安定せず、光波距離計内部の種々の設定ができない。そこで、演算処理部において、各受光部の増幅度を決める場合は、信号切換回路からは設定用ミキサーによる低周波信号が出力されるようにし、PLL制御回路を早期に安定状態に入るようにする。PLL制御回路が安定すれば、各増幅度を決定することができる。増幅度が決められた後は、信号切換回路からは整調用信号が出力されるようにし、係る増幅度のもとで受光部への受光光量を調整する濃度フィルタの位置決めを行い、整調用信号振幅を調整し、PLL制御回路を安定状態にする。PLL制御回路が安定すれば、測距を行うことができ、請求項1の効果が発揮される。   (Operation) At the time of manufacturing the optical distance meter according to the present invention, the initial PLL control circuit does not determine the amplification degree of each light receiving unit, so the output signal of the PLL circuit is not stable, and various internal components of the optical distance meter Cannot set. Therefore, in the arithmetic processing unit, when determining the amplification degree of each light receiving unit, the signal switching circuit outputs a low frequency signal from the setting mixer so that the PLL control circuit enters the stable state at an early stage. . If the PLL control circuit is stabilized, each amplification degree can be determined. After the amplification degree is determined, a pacing signal is output from the signal switching circuit, and the density filter that adjusts the amount of received light to the light receiving unit is positioned based on the amplification degree. The amplitude is adjusted to bring the PLL control circuit into a stable state. If the PLL control circuit is stabilized, distance measurement can be performed, and the effect of claim 1 is exhibited.

請求項3においては、請求項1または請求項2に記載の光波距離計において、前記大きさの異なる複数変調周波数のうち、最も周波数の大きい第1周波数には、前記整調用信号が入力される前記PLL制御回路を用い、前記第1周波数より周波数の低い第2周波数には、前記周波数発振器からの固定周波数信号が入力される第2回路用ミキサーを備えた第2のPLL制御回路を設けた。   According to a third aspect of the present invention, in the optical wave distance meter according to the first or second aspect, the pacing signal is input to a first frequency having the largest frequency among the plurality of modulation frequencies having different sizes. Using the PLL control circuit, a second PLL control circuit having a second circuit mixer to which a fixed frequency signal from the frequency oscillator is input is provided at a second frequency lower than the first frequency. .

(作用)第1周波数より周波数が低い第2周波数では、生じる位相ドリフトが第1周波数よりも当然に少ないという周知の事実から、第2周波数において、第1の周波数と同一のPLL制御回路(同一の発振器)を用いると、第1周波数における位相ドリフトと同程度の大きさの位相ドリフトが含まれてしまう。そこで、上記事実に着眼し、第2の周波数には、別個のPLL制御回路(周波数発振器からの固定周波数信号を用いてPLL回路出力信号を生成するPLL制御回路)を用いたほうが、第2周波数において顕れる位相ドリフトは小さくなる。   (Operation) Due to the well-known fact that the generated phase drift is naturally less than that of the first frequency at the second frequency lower than the first frequency, the same PLL control circuit (same as the first frequency) at the second frequency. If the oscillator is used, a phase drift of the same magnitude as the phase drift at the first frequency is included. Therefore, paying attention to the above fact, it is better to use a separate PLL control circuit (a PLL control circuit that generates a PLL circuit output signal using a fixed frequency signal from a frequency oscillator) as the second frequency. The phase drift that appears in is small.

以上より、請求項1に係る発明によれば、2つの発光素子を択一的に発光させることで、測距信号,参照信号の位相をそれぞれ測定できる構成とし、かつ、発光素子,受光素子等の温度位相ドリフト、更には受光部を異にすることによる(使用電気回路の相違による)原因不明な位相ドリフトを全て含む信号を、故意にPLL制御回路の整調用信号として用い、該PLL回路出力信号を第1及び第2の受光部の周波数変換器に入力することで、測距信号と参照信号の位相差をとったときには、既知の固定位相ドリフトのみが残り、原因不明な位相ドリフトは全て除去されるため、様々な位相ドリフトにより生じる測距値誤差が大幅に低減される。   As described above, according to the first aspect of the present invention, it is possible to measure the phase of the ranging signal and the reference signal by selectively emitting light from the two light emitting elements, and the light emitting element, the light receiving element, etc. A signal including all the phase drifts of unknown causes (due to the difference in the electric circuit used) due to the difference in the temperature phase drift of the light receiving unit is intentionally used as a pacing signal for the PLL control circuit, and the PLL circuit output When the phase difference between the distance measurement signal and the reference signal is obtained by inputting the signal to the frequency converters of the first and second light receiving units, only the known fixed phase drift remains, and all the phase drifts with unknown causes remain. Since it is eliminated, distance measurement error caused by various phase drifts is greatly reduced.

また、特許文献2では、2つの発光素子に異なる2種類の送光信号が用意されており、電波干渉によって送光信号が相互に漏れこみ、測距値誤差の一因になるという問題があったが、本願発明では、送光信号は1種類しか用意しないため、電波干渉による上記誤差は生じない。   Further, in Patent Document 2, two different types of light transmission signals are prepared for two light emitting elements, and there is a problem that the light transmission signals leak into each other due to radio wave interference and contribute to distance measurement error. However, in the present invention, since only one type of light transmission signal is prepared, the above error due to radio wave interference does not occur.

また、特許文献2では、A/D変換器に入力される信号には周波数が異なる複数の中間周波信号があるため、これらをデジタルフィルタで分離している。しかし、プリズム測距の場合、測距光が大気の揺らぎの影響でプリズム視準位置が時折ずれ、振幅変調と同じ影響を受ける。その変調周波数は数Hz〜数kHzにまで及ぶため、A/D変換器に入力した測距光の周波数と参照光の周波数が近接(数kHz程度の差)していると、大気の揺らぎの影響で参照信号に測距信号が合成され、参照信号に測定誤差がおこるという問題があるが、本願発明では、A/D変換器に入力する中間周波信号は1種類しかないため、これを原因とする誤差は生じない。   In Patent Document 2, since a signal input to the A / D converter includes a plurality of intermediate frequency signals having different frequencies, these are separated by a digital filter. However, in the case of prism distance measurement, the distance collimated light is sometimes shifted due to the influence of atmospheric fluctuations, and is affected by the same effect as amplitude modulation. Since the modulation frequency ranges from several Hz to several kHz, if the frequency of the ranging light input to the A / D converter and the frequency of the reference light are close (difference of about several kHz), the fluctuation of the atmosphere There is a problem in that a ranging signal is combined with a reference signal due to the influence, and a measurement error occurs in the reference signal. However, in the present invention, there is only one type of intermediate frequency signal input to the A / D converter. No error occurs.

請求項2に係る発明によれば、請求項1の効果を発揮させるための光波距離計内部の様々な初期調整を、正確適切に行うことができる。   According to the second aspect of the present invention, various initial adjustments inside the optical distance meter for achieving the effect of the first aspect can be accurately and appropriately performed.

請求項3に係る発明によれば、第1周波数と第2周波数に用いるPLL制御回路(発振器)を別にしたことで、第2周波数には第1周波数の位相ドリフトは含まれず、顕れる位相ドリフトが小さいため、周波数の低い第2周波数にとってより優位な構成となり、さらに測距値誤差を低減することができる。   According to the invention of claim 3, by separating the PLL control circuit (oscillator) used for the first frequency and the second frequency, the second frequency does not include the phase drift of the first frequency, and the apparent phase drift does not occur. Since it is small, the configuration is more advantageous for the second frequency having a low frequency, and the distance measurement value error can be further reduced.

本願発明の第1の実施例に係る光波距離計のブロック図である。1 is a block diagram of a lightwave distance meter according to a first embodiment of the present invention. 同光波距離計において、様々な位相ドリフトが除去される理由を説明するための図である。It is a figure for demonstrating the reason that various phase drifts are removed in the same optical distance meter. 同光波距離計で得た測距値を示すグラフである。It is a graph which shows the ranging value obtained with the same light wave rangefinder. 従来の光波距離計で得た測距値を示すグラフである。It is a graph which shows the ranging value obtained with the conventional lightwave distance meter. 本願発明の第2の実施例に係る光波距離計のブロック図である。It is a block diagram of the lightwave distance meter which concerns on 2nd Example of this invention.

以下に図1に基づいて、本願発明の光波距離計の第1の実施例の構成を説明する。実施例の光波距離計は、測距光と参照光との位相差から目標反射物22までの距離を算出する位相差方式の光波距離計であって、測距光路と参照光路の光路切換えのためのシャッターを省くため、2つの発光素子と2つの受光素子、即ち、発光素子6,発光素子8と、受光素子40,受光素子60と、を使用したものである。そして、以下に示すように、受光素子40に接続され、主として周波数変換器42,45,48と増幅器41,43,46,49を備える第1の受光部300と、受光素子60に接続され、主として周波数変換器62,65,68と増幅器61,63,66,69を備える第2の受光部400と、発光素子6と発光素子8の発光切換手段である発光切換回路4と、第2の受光部400を経た中間周波信号が帰還されて整調用信号として入力される第1のPLL制御回路100と、さらに、同光波距離計の製造時に各種設定を実現するための、設定用ミキサー13と、信号切換回路14と、演算処理部80と、を構成要素に含む。   The configuration of the first embodiment of the lightwave distance meter according to the present invention will be described below with reference to FIG. The lightwave distance meter of the embodiment is a phase difference type lightwave distance meter that calculates the distance to the target reflector 22 from the phase difference between the distance measurement light and the reference light, and switches the optical path between the distance measurement optical path and the reference optical path. In order to omit the shutter, the two light emitting elements and the two light receiving elements, that is, the light emitting element 6, the light emitting element 8, the light receiving element 40, and the light receiving element 60 are used. And, as shown below, connected to the light receiving element 40, connected to the first light receiving unit 300 mainly including the frequency converters 42, 45, 48 and the amplifiers 41, 43, 46, 49, and the light receiving element 60, A second light receiving unit 400 mainly including frequency converters 62, 65, 68 and amplifiers 61, 63, 66, 69; a light emission switching circuit 4 which is a light emission switching means of the light emitting element 6 and the light emitting element 8; A first PLL control circuit 100 to which an intermediate frequency signal passed through the light receiving unit 400 is fed back and input as a pacing signal, and a setting mixer 13 for realizing various settings when manufacturing the optical distance meter The signal switching circuit 14 and the arithmetic processing unit 80 are included in the constituent elements.

周波数発振器1から生成された周波数F1は、分周部2,9に入力される。分周部2ではF1を分周し、周波数F2,F3及びF3+△f3を出力する。周波数F1,F2,F3は、F1から順に周波数が低いものとなっており、それぞれの分解能に応じて測距値の各桁が決定される。F3+△f3信号は、周波数変換器42,62へと入力される。周波数重畳回路3ではF1,F2,F3信号を重畳する。発光切換回路4は重畳信号F1,F2,F3を駆動回路5,7のどちらか一方に出力し同時には出力しない。駆動回路5からの重畳信号F1,F2,F3は発光素子6に入力され、駆動回路7からの重畳信号F1,F2,F3は発光素子8に入力される。即ち、発光素子6,8は、発光切換回路4によって交互に切り換えられて択一的に発光し、同時には発光しない。   The frequency F1 generated from the frequency oscillator 1 is input to the frequency dividers 2 and 9. The frequency divider 2 divides F1 and outputs frequencies F2, F3 and F3 + Δf3. The frequencies F1, F2, and F3 have a lower frequency in order from F1, and each digit of the distance measurement value is determined according to each resolution. The F3 + Δf3 signal is input to the frequency converters 42 and 62. The frequency superimposing circuit 3 superimposes the F1, F2, and F3 signals. The light emission switching circuit 4 outputs the superimposed signals F1, F2, and F3 to one of the drive circuits 5 and 7, but does not output them simultaneously. The superimposed signals F1, F2, and F3 from the drive circuit 5 are input to the light emitting element 6, and the superimposed signals F1, F2, and F3 from the drive circuit 7 are input to the light emitting element 8. That is, the light emitting elements 6 and 8 are alternately switched by the light emission switching circuit 4 and selectively emit light, but do not emit light simultaneously.

分周部9では、F1を分周して周波数△f1yを生成し、第1のPLL(フェーズロックループ)制御回路100へ、比較用の固定周波数信号として入力する。第1のPLL制御回路100は、位相比較器10,ループフィルタ11,回路内発振器12を備え、回路内発振器12からの出力周波数(PLL回路出力信号)を安定させることができる。位相比較器10には後述する増幅器71からの整調用信号△f1xと分周部9からの固定周波数信号△f1yが入力される。初期状態では、△f1x,△f1yは周波数が異なっている。位相比較器10では初期位相の差を出力する。ループフィルタ11は第1のPLL制御回路100の性能を決めるフィルタであり平滑後に電圧を出力する。回路内発振器12はループフィルタ11からの出力電圧により周波数が決定され、第1のPLL制御回路100により安定したPLL回路出力信号F1+△f1を周波数変換器48,68へ出力する。このとき、△f1xと△f1yは周波数が同じで位相が異なっている。一方、周波数生成回路19ではF2+△f2を生成し、周波数変換器45,65へと出力する。   The frequency divider 9 divides F1 to generate a frequency Δf1y, which is input to the first PLL (phase lock loop) control circuit 100 as a fixed frequency signal for comparison. The first PLL control circuit 100 includes a phase comparator 10, a loop filter 11, and an in-circuit oscillator 12, and can stabilize the output frequency (PLL circuit output signal) from the in-circuit oscillator 12. The phase comparator 10 receives a pacing signal Δf1x from an amplifier 71, which will be described later, and a fixed frequency signal Δf1y from the frequency divider 9. In the initial state, Δf1x and Δf1y have different frequencies. The phase comparator 10 outputs an initial phase difference. The loop filter 11 is a filter that determines the performance of the first PLL control circuit 100, and outputs a voltage after smoothing. The in-circuit oscillator 12 has a frequency determined by the output voltage from the loop filter 11, and outputs a stable PLL circuit output signal F 1 + Δf 1 to the frequency converters 48 and 68 by the first PLL control circuit 100. At this time, Δf1x and Δf1y have the same frequency and different phases. On the other hand, the frequency generation circuit 19 generates F2 + Δf2 and outputs it to the frequency converters 45 and 65.

また、第1のPLL制御回路100には、PLL回路出力信号F1+△f1及び周波数発振器1からの固定周波数信号F1が入力されて低周波信号△f1を出力する設定用ミキサー13と、設定用ミキサー13からの低周波信号△f1又は整調用信号△f1xのいずれか一方を選択的に位相比較器10に出力する信号切換回路14が設けられている。信号切換回路14は、後述する演算処理部80の指令により、信号△f1と信号△f1xのいずれか一方を位相比較器10へ出力する。これにより、光波距離計内部の種々の初期設定が正確適切に行われる。   The first PLL control circuit 100 receives a PLL circuit output signal F1 + Δf1 and a fixed frequency signal F1 from the frequency oscillator 1 and outputs a low frequency signal Δf1, and a setting mixer. A signal switching circuit 14 for selectively outputting either the low frequency signal Δf1 or the pacing signal Δf1x from 13 to the phase comparator 10 is provided. The signal switching circuit 14 outputs either the signal Δf1 or the signal Δf1x to the phase comparator 10 according to a command from the arithmetic processing unit 80 described later. As a result, various initial settings inside the optical distance meter are accurately and appropriately performed.

発光素子6から出射された光はビームスプリッタ20で2つに分割され、一方の光は、測距光路21を経て目標反射物22で反射され測距光路23を経て光量調整用濃度フィルタ24を通過し受光光学25で集光され受光素子40に到達する。他方の光は、第1の参照光路26を経て光量調整用濃度フィルタ27を通過し受光素子60に到達する。   The light emitted from the light emitting element 6 is split into two by the beam splitter 20, and one light is reflected by the target reflector 22 through the distance measuring optical path 21, and passes through the distance measuring optical path 23 and passes through the distance adjusting optical path 23. The light passes through and is collected by the light receiving optics 25 and reaches the light receiving element 40. The other light passes through the first reference optical path 26, passes through the light amount adjusting density filter 27, and reaches the light receiving element 60.

発光素子8から出射された光はビームスプリッタ28で2つに分割され、一方の光は、第3の参照光路29を経て光量調整用濃度フィルタ30を通過し受光素子40に到達する。他方の光は、第2の参照光路31を経て光量調整用濃度フィルタ32を通過し受光素子60に到達する。   The light emitted from the light emitting element 8 is divided into two by the beam splitter 28, and one light passes through the third reference optical path 29, passes through the light quantity adjusting density filter 30, and reaches the light receiving element 40. The other light passes through the second reference light path 31, passes through the light amount adjusting density filter 32, and reaches the light receiving element 60.

受光素子40で受光された光は、3つの周波数F1,F2,F3をもつ信号に変換される。これらは増幅器41で信号振幅を増幅された後、周波数変換器42,45,48に入力される。周波数変換器42では周波数F3+△f3が入力されることで周波数乗算が行われる。乗算後△f3が得られ、増幅器43により最適な信号レベルに増幅された後にA/D変換器44に入力される。周波数変換器45では周波数F2+△f2が入力されることで周波数乗算が行われる。乗算後△f2が得られ、増幅器46により最適な信号レベルに増幅された後にA/D変換器47に入力される。周波数変換器48では周波数F1+△f1が入力されることで周波数乗算が行われる。乗算後△f1が得られ、増幅器49により最適な信号レベルに増幅された後にA/D変換器50に入力される。   The light received by the light receiving element 40 is converted into a signal having three frequencies F1, F2, and F3. These signals are amplified by the amplifier 41 and then input to the frequency converters 42, 45 and 48. The frequency converter 42 performs frequency multiplication by inputting the frequency F3 + Δf3. After the multiplication, Δf3 is obtained, amplified to an optimum signal level by the amplifier 43, and input to the A / D converter 44. The frequency converter 45 performs frequency multiplication by inputting the frequency F2 + Δf2. After multiplication, Δf2 is obtained, amplified to an optimum signal level by the amplifier 46, and input to the A / D converter 47. The frequency converter 48 receives the frequency F1 + Δf1 and performs frequency multiplication. After the multiplication, Δf1 is obtained, amplified to an optimum signal level by the amplifier 49, and input to the A / D converter 50.

同様に、受光素子60で受光された光は、3つの周波数F1,F2,F3をもつ信号に変換される。これらは増幅器61で信号振幅を増幅された後、周波数変換器62,65,68に入力される。周波数変換器62では周波数F3+△f3が入力されることで周波数乗算が行われる。乗算後△f3が得られ、増幅器63により最適な信号レベルに増幅された後にA/D変換器64に入力される。周波数変換器65では周波数F2+△f2が入力されることで周波数乗算が行われる。乗算後△f2が得られ、増幅器66により最適な信号レベルに増幅された後にA/D変換器67に入力される。周波数変換器68では周波数F1+△f1が入力されることで周波数乗算が行われる。乗算後△f1が得られ、増幅器69により最適な信号レベルに増幅された後にA/D変換器70に入力される。   Similarly, the light received by the light receiving element 60 is converted into a signal having three frequencies F1, F2, and F3. These signals are amplified by the amplifier 61 and then input to the frequency converters 62, 65 and 68. The frequency converter 62 performs frequency multiplication by inputting the frequency F3 + Δf3. After multiplication, Δf3 is obtained, amplified to an optimum signal level by the amplifier 63, and input to the A / D converter 64. The frequency converter 65 performs frequency multiplication by inputting the frequency F2 + Δf2. After the multiplication, Δf2 is obtained, amplified to an optimum signal level by the amplifier 66, and input to the A / D converter 67. The frequency converter 68 receives the frequency F1 + Δf1 and performs frequency multiplication. After the multiplication, Δf1 is obtained, amplified to an optimum signal level by the amplifier 69, and input to the A / D converter 70.

ここで、増幅器69からの出力信号△f1は、デジタル処理が可能な信号レベルにまで増幅器71にて増幅され、整調用信号△f1xとして、第1のPLL制御回路100の位相比較器10へ(信号切換回路14によって選択的に)帰還されて、第1のPLL制御回路100の一部として使用される。   Here, the output signal Δf1 from the amplifier 69 is amplified by the amplifier 71 to a signal level that allows digital processing, and is sent to the phase comparator 10 of the first PLL control circuit 100 as a pacing signal Δf1x ( The signal is selectively fed back by the signal switching circuit 14 and used as part of the first PLL control circuit 100.

A/D変換器44,47,50,64,67,70では、アナログ信号を多値デジタル信号に変換し、演算処理部80にて信号の振幅情報、位相情報を取得できるようにする。振幅情報は、後述のように、濃度フィルタ24,27,30,32の調整に活用される。   The A / D converters 44, 47, 50, 64, 67 and 70 convert the analog signal into a multi-value digital signal so that the arithmetic processing unit 80 can acquire the amplitude information and phase information of the signal. The amplitude information is used for adjusting the density filters 24, 27, 30, and 32 as will be described later.

本実施例の光波距離計の製造時において、まず、第1の受光部300における増幅器41,43,46,49の増幅度と、第2の受光部400における増幅器61,63,66,69の増幅度を決める必要がある。増幅度を決める条件は、目標反射物22から返ってくる光強度と目標反射物22までの距離によって決められる。   At the time of manufacturing the optical distance meter of the present embodiment, first, the amplification degree of the amplifiers 41, 43, 46, and 49 in the first light receiving unit 300 and the amplifiers 61, 63, 66, and 69 in the second light receiving unit 400 are firstly described. It is necessary to determine the degree of amplification. The condition for determining the amplification degree is determined by the light intensity returned from the target reflector 22 and the distance to the target reflector 22.

増幅度調整のためには、A/D変換器44,47,50,64,67,70に安定した信号を入力させ、信号振幅測定のために最適な振幅となるようにする必要がある。このとき、第1のPLL制御回路100は安定状態になければならないが、濃度フィルタ27,32の位置も増幅器61,69,71の増幅度も決まっていない初期状態で、Δf1の信号振幅がデジタル処理が可能な信号レベルに達していない場合、第1のPLL制御回路100のPLL回路出力信号は安定状態にない。   In order to adjust the amplification degree, it is necessary to input a stable signal to the A / D converters 44, 47, 50, 64, 67, and 70 so as to obtain an optimum amplitude for signal amplitude measurement. At this time, the first PLL control circuit 100 must be in a stable state, but the signal amplitude of Δf1 is digital in an initial state in which the positions of the density filters 27 and 32 and the amplification degrees of the amplifiers 61, 69, and 71 are not determined. If the signal level that can be processed has not been reached, the PLL circuit output signal of the first PLL control circuit 100 is not in a stable state.

そこで、初期状態でも第1のPLL制御回路100を確実に安定状態にさせるために、信号切換回路14は、演算処理部80の制御により、信号△f1か△f1xのどちらかを選択的に出力するようになっている。   Therefore, in order to ensure that the first PLL control circuit 100 is in a stable state even in the initial state, the signal switching circuit 14 selectively outputs either the signal Δf1 or Δf1x under the control of the arithmetic processing unit 80. It is supposed to be.

即ち、初期設定時、信号切換回路14からは△f1信号が出力されるように制御され、第1のPLL制御回路100が早期に安定状態に入るようにする。PLL回路出力信号が安定すれば、各増幅度を決定することができる。なお、第2の受光部400の増幅器61,63,66,69の増幅度はそれぞれ第1の受光部300の増幅器41,43,46,49と同等でよい。   That is, at the time of initial setting, the signal switching circuit 14 is controlled so as to output the Δf1 signal so that the first PLL control circuit 100 enters the stable state at an early stage. If the PLL circuit output signal is stabilized, each amplification degree can be determined. Note that the amplification degrees of the amplifiers 61, 63, 66, and 69 of the second light receiving unit 400 may be equivalent to the amplifiers 41, 43, 46, and 49 of the first light receiving unit 300, respectively.

増幅度が決められた後は、信号切換回路14からは整調用信号△f1xが出力されるように制御し、係る増幅度のもとで、第1の受光部300及び第2の受光部400への受光光量を調整する各濃度フィルタ27,30,32の位置決めを行う。   After the amplification degree is determined, the signal switching circuit 14 is controlled to output the pacing signal Δf1x, and the first light receiving unit 300 and the second light receiving unit 400 are controlled based on the amplification degree. Each density filter 27, 30, 32 for adjusting the amount of received light is positioned.

第1の参照光路26上にある濃度フィルタ27については、発光素子6を発光させ、A/D変換器64で測定される△f3信号レベル、あるいはA/D変換器67で測定される△f2信号レベル、あるいはA/D変換器70で測定される△f1信号レベルが最適になるように位置決めを行う。第3の参照光路29上にある濃度フィルタ30については、発光素子8を発光させ、A/D変換器44で測定される△f3信号レベル、あるいはA/D変換器47で測定される△f2信号レベル、あるいはA/D変換器50で測定される△f1信号レベルが最適になるように位置決めを行う。第2の参照光路31上にある濃度フィルタ32については、発光素子8を発光させ、A/D変換器64で測定される△f3信号レベル、あるいはA/D変換器67で測定される△f2信号レベル、あるいはA/D変換器70で測定される△f1信号レベルが最適になるように位置決めを行う。なお、測距光路23にある濃度フィルタ24については、目標反射物22の反射率により受光レベルが変化するため、演算処理部80による絞り制御信号81により位置調整を測距毎に行うため位置決めはしない。   For the density filter 27 on the first reference optical path 26, the light emitting element 6 emits light, and the Δf3 signal level measured by the A / D converter 64 or Δf2 measured by the A / D converter 67. Positioning is performed so that the signal level or the Δf1 signal level measured by the A / D converter 70 is optimized. For the density filter 30 on the third reference optical path 29, the light emitting element 8 emits light, and the Δf3 signal level measured by the A / D converter 44 or Δf2 measured by the A / D converter 47. Positioning is performed so that the signal level or the Δf1 signal level measured by the A / D converter 50 is optimized. For the density filter 32 on the second reference optical path 31, the light emitting element 8 emits light, and the Δf3 signal level measured by the A / D converter 64 or Δf2 measured by the A / D converter 67. Positioning is performed so that the signal level or the Δf1 signal level measured by the A / D converter 70 is optimized. Since the light receiving level of the density filter 24 in the distance measuring optical path 23 varies depending on the reflectance of the target reflector 22, the position adjustment is performed for each distance measurement by the aperture control signal 81 from the arithmetic processing unit 80. do not do.

各濃度フィルタ27,30,32の位置決め後、整調用信号△f1xの振幅を増幅器71の増幅度により調整し、第1のPLL制御回路100を再び安定状態にする。PLL回路出力信号F1+△f1が安定すれば、種々の初期設定が完了となり、以下の通り測距を行うことができる。   After positioning the density filters 27, 30, and 32, the amplitude of the pacing signal Δf1x is adjusted by the amplification degree of the amplifier 71, and the first PLL control circuit 100 is brought into a stable state again. If the PLL circuit output signal F1 + Δf1 is stabilized, various initial settings are completed, and ranging can be performed as follows.

まず、発光素子8を発光させ、第2の参照光路31および位置決めした濃度フィルタ32を通過した光は受光素子60により電気信号に変換され、増幅器61,周波数変換器68,増幅器69,増幅器71を経て位相比較器10へ入力され、回路内発振器12からのPLL回路出力信号F1+△f1はPLL安定状態に入る。同様に、周波数生成回路19から出力される信号F2+△f2もPLL安定状態に入る。ここで、第2の参照光路31,第3の参照光路29について測距を行い、F1,F2,F3それぞれ2つずつの測距値を得る。   First, the light emitting element 8 emits light, and the light passing through the second reference light path 31 and the positioned density filter 32 is converted into an electric signal by the light receiving element 60, and the amplifier 61, the frequency converter 68, the amplifier 69, and the amplifier 71 are turned on. Then, it is input to the phase comparator 10 and the PLL circuit output signal F1 + Δf1 from the in-circuit oscillator 12 enters the PLL stable state. Similarly, the signal F2 + Δf2 output from the frequency generation circuit 19 also enters the PLL stable state. Here, distance measurement is performed for the second reference light path 31 and the third reference light path 29, and two distance measurement values are obtained for each of F1, F2, and F3.

次に、発光切換回路4により、今度は発光素子6を発光させる。第1の参照光路26および位置決めした濃度フィルタ27を通過した光は受光素子60により電気信号に変換され、増幅器61,周波数変換器68,増幅器69,増幅器71を経て位相比較器10へ入力され、PLL回路出力信号F1+△f1はPLL安定状態に入る。F2+△f2も同様にPLL安定状態に入る。ここで、第1の参照光路26および測距光路21について測距を行い、F1,F2,F3それぞれ2つずつの測距値を得る。なお、発光切換回路4で切り換える前後で、位相比較器10に入力される信号振幅は、各濃度フィルタ27,32の位置決めを既にしてあるので、同じ振幅になる。したがって第1のPLL制御回路100を正常に動作させることが可能である。   Next, the light emission switching circuit 4 causes the light emitting element 6 to emit light. The light that has passed through the first reference optical path 26 and the positioned density filter 27 is converted into an electric signal by the light receiving element 60, and is input to the phase comparator 10 through the amplifier 61, the frequency converter 68, the amplifier 69, and the amplifier 71. The PLL circuit output signal F1 + Δf1 enters the PLL stable state. Similarly, F2 + Δf2 enters the PLL stable state. Here, ranging is performed for the first reference optical path 26 and the ranging optical path 21, and two ranging values are obtained for each of F1, F2, and F3. The signal amplitude input to the phase comparator 10 before and after switching by the light emission switching circuit 4 has the same amplitude because the density filters 27 and 32 have already been positioned. Therefore, the first PLL control circuit 100 can be operated normally.

そして、発光切換回路4の切換前後で得られた測距値、即ち、発光素子6,8の択一的発光により得られた測距信号と参照信号の位相差から、目標反射物22までの測距値が算出される。この際、各発光素子、各受光素子、各増幅器及び周波数変換器等の電気部品の温度位相ドリフト、受光部を異にすること(電気回路を異にすること)によって生じる原因不明な位相ドリフトが、全て除去される。
ここで、上記に述べる様々な位相ドリフトが除去される理由について、図2に基づいて説明する。温度位相ドリフトは信号F1,F2,F3全てに起きる現象であるが、ドリフト量はF1,F2,F3の順に小さくなるので、最も周波数の大きい信号F1を用いて説明する。なお、信号F3のドリフトは微少であるので説明しない。
Then, the distance measurement value obtained before and after switching of the light emission switching circuit 4, that is, the phase difference between the distance measurement signal obtained by the selective light emission of the light emitting elements 6 and 8 and the reference signal, to the target reflector 22 A distance measurement value is calculated. At this time, the temperature phase drift of electrical components such as each light emitting element, each light receiving element, each amplifier and frequency converter, and phase drift of unknown cause caused by different light receiving parts (different electric circuits) All removed.
Here, the reason why the various phase drifts described above are eliminated will be described with reference to FIG. The temperature phase drift is a phenomenon that occurs in all of the signals F1, F2, and F3. Since the drift amount decreases in the order of F1, F2, and F3, the signal F1 having the highest frequency will be described. Since the drift of the signal F3 is very small, it will not be described.

図2は、信号F1についての位相ドリフトおよび固定位相を示している。図2における各記号は、次のように定義される。
φLD1:発光素子6の温度位相ドリフト
φLD2:発光素子8の温度位相ドリフト
φ:測距光路21,23(光波距離計と目標反射物22までの往復距離分)の固定位相
φC1:第1の参照光路26の固定位相
φC2:第2の参照光路31の固定位相
φC3:第3の参照光路29の固定位相
φAPD1:受光素子40の温度位相ドリフト
φAPD2:受光素子60の温度位相ドリフト
φRFAMP1:増幅器41(周波数変換器48を含む)の温度位相ドリフト
φRFAMP2:増幅器61(周波数変換器68を含む)の温度位相ドリフト
φLO: Local信号の初期位相
φIFAMP1 :増幅器49の温度位相ドリフト
φIFAMP2:増幅器69の温度位相ドリフト
φIFAMP3 :増幅器71の温度位相ドリフト
φX1:第1の受光部300の信号F1に係る部分301の不明位相ドリフト
φX2:第2の受光部400の信号F1に係る部分401の不明位相ドリフト。
FIG. 2 shows the phase drift and fixed phase for signal F1. Each symbol in FIG. 2 is defined as follows.
φ LD1 : Temperature phase drift of the light emitting element 6 φ LD2 : Temperature phase drift of the light emitting element 8 φ M : Fixed phase φ R1 of the distance measuring optical paths 21 and 23 (the reciprocating distance to the light wave rangefinder and the target reflector 22) φ C1 : Fixed phase φ C2 of the first reference optical path 26: Fixed phase φ C3 of the second reference optical path 31: Fixed phase φ APD1 of the third reference optical path 29: Temperature phase drift φ APD2 of the light receiving element 40: Temperature phase drift φ RFAMP1 : Temperature phase drift φ AMAMP2 of the amplifier 41 (including the frequency converter 48): Temperature phase drift φ AM of the amplifier 61 (including the frequency converter 68) LO : Initial phase φ IFAMP1 of the local signal: Amplifier 49 temperature phase drift φ IFAMP2: temperature of the amplifier 69 phase drift φ IFAMP3: temperature of the amplifier 71 phase drift phi X1: first Unknown phase drift part 301 according to the signal F1 of the light receiving portion 300 phi X2: unknown phase drift part 401 according to the signal F1 of the second light receiving portion 400.

まず、発光素子8を発光させる。受光部401から得られる安定した信号レベルの整調用信号△f1xが第1のPLL制御回路100に入力され、PLL制御回路100が安定状態に入る。Local信号F1+△f1も安定した周波数になる。このときのLocal信号の位相φは、

Figure 0005730094
・・・(1)
である。この状態で測距を行うと、A/D変換器50で測定される信号位相φは、
Figure 0005730094
・・・(2)
であり、A/D変換器70で測定される信号位相φ は、
Figure 0005730094
・・・(3)
となる。φをφに代入すると、
Figure 0005730094
・・・(4)
Figure 0005730094
・・・(5)
となり、式(4)と式(5)の差を取ると、
Figure 0005730094
・・・(6)
となる。 First, the light emitting element 8 is caused to emit light. A pacing signal Δf1x having a stable signal level obtained from the light receiving unit 401 is input to the first PLL control circuit 100, and the PLL control circuit 100 enters a stable state. The local signal F1 + Δf1 also has a stable frequency. The phase φ 1 of the Local signal at this time is
Figure 0005730094
... (1)
It is. When ranging is performed in this state, the signal phase φ A measured by the A / D converter 50 is
Figure 0005730094
... (2)
The signal phase φ B measured by the A / D converter 70 is
Figure 0005730094
... (3)
It becomes. Substituting φ 1 into φ A and φ B ,
Figure 0005730094
... (4)
Figure 0005730094
... (5)
And taking the difference between Equation (4) and Equation (5),
Figure 0005730094
... (6)
It becomes.

次に発光素子6を発光させる。受光部401から得られる安定した信号レベルの整調用信号△f1xが第1のPLL制御回路100に入力され、第1のPLL制御回路100が安定状態に入る。Local信号F1+△f1も安定した周波数になる。このときのLocal信号の位相φ は、

Figure 0005730094
・・・(7)
である。この状態で測距を行うと、A/D変換器50で測定される信号位相φは、
Figure 0005730094
・・・(8)
であり、A/D変換器70で測定される信号位相φは、
Figure 0005730094
・・・(9)
となる。φをφに代入すると、
Figure 0005730094
・・・(10)
Figure 0005730094
・・・(11)
となり、式(10)と式(11)の差を取ると、
Figure 0005730094
・・・(12)
となる。 Next, the light emitting element 6 emits light. A pacing signal Δf1x having a stable signal level obtained from the light receiving unit 401 is input to the first PLL control circuit 100, and the first PLL control circuit 100 enters a stable state. The local signal F1 + Δf1 also has a stable frequency. The phase φ 2 of the Local signal at this time is
Figure 0005730094
... (7)
It is. When ranging is performed in this state, the signal phase φ C measured by the A / D converter 50 is
Figure 0005730094
... (8)
The signal phase φ D measured by the A / D converter 70 is
Figure 0005730094
... (9)
It becomes. Substituting φ 2 into φ C and φ D ,
Figure 0005730094
(10)
Figure 0005730094
(11)
And taking the difference between Equation (10) and Equation (11),
Figure 0005730094
(12)
It becomes.

ここで、式(6)と式(12)の差、即ちφ−φとφ−φの差を取ると、

Figure 0005730094
・・・(13)
を得る。式(13)は、発光素子6,8の温度位相ドリフトφLD1LD2、受光素子40,60の温度位相ドリフトφAPD1APD2、受光部301における電気部品による位相ドリフトφRFAMP1,φIFAMP1、受光部401における電気部品による位相ドリフトφRFAMP2,φIFAMP2,φIFAMP3は除去され、測距光路,参照光路の固定位相φC1C3C2のみとなっている。このことから、各発光素子,各受光素子,各周波数変換器等の電気部品の温度位相ドリフトが大幅に低減されている。さらに、受光部301と受光部401において電気回路が異なることによって生じる原因不明な位相ドリフトφX1,φX2は完全に除去されていることが判る。なお、信号F1の場合、φ, φは同じ値であるため、φ, φ を測定しなくとも、式(6)から同様の式を得られる。 Here, when the difference between Expression (6) and Expression (12), that is, the difference between φ A −φ B and φ C −φ D is taken,
Figure 0005730094
... (13)
Get. Equation (13), the temperature phase drift phi LD1 of the light-emitting element 6, 8, phi LD2, temperature phase drift phi APD1 of the light receiving elements 40, 60, phi APD 2, phase drift phi RFAMP1 by electrical components in the light receiving unit 301, phi IFAmp1 The phase drifts φ RFAMP2 , φ IFAMP2 , φ IFAMP3 due to electric components in the light receiving unit 401 are removed, and only the fixed phases φ M , φ C1 , φ C3 , φ C2 of the distance measuring optical path and the reference optical path are provided. For this reason, the temperature phase drift of electrical components such as each light emitting element, each light receiving element, and each frequency converter is greatly reduced. Further, it can be seen that the phase drifts φ X1 and φ X2 whose causes are unknown due to the difference in the electric circuit between the light receiving unit 301 and the light receiving unit 401 are completely removed. In the case of the signal F1, since φ B and φ D have the same value, the same formula can be obtained from the formula (6) without measuring φ B and φ D.

また、信号F2の場合は、信号F1と共通の回路内発振器12を使用するため、位相φ , φ は信号F1についての位相となる。よって、φ−φの式(式(6))のみでは、信号F2本来の位相ドリフトよりも大きなドリフトが残ることになる。そのため、φ, φ も測定し、式(13)から位相φ , φを除去すればよい。 Further, in the case of the signal F2, since the in-circuit oscillator 12 common to the signal F1 is used, the phases φ 1 and φ 2 are phases with respect to the signal F1. Therefore, a drift larger than the original phase drift of the signal F2 remains only in the formula of φ A −φ B (formula (6)). Therefore, φ B and φ D are also measured, and the phases φ 1 and φ 2 may be removed from the equation (13).

本実施例によれば、2つの発光素子6,8を択一的に発光させることで、測距信号,参照信号の位相をそれぞれ測定できる構成とし、かつ、上記の様々な位相ドリフトに追随した位相を持つ△f1xを、故意に、第1のPLL制御回路100の整調用信号として用い、PLL回路出力信号f1+△f1を周波数変換器48及び周波数変換器68に入力することで、発光素子6を発光させて測距すると、受光部301の周波数変換器48及び受光部401の周波数変換器68を介して測距信号の位相ドリフトは略除去され、その後A/D変換器50,70で測定される測距信号の位相ドリフトには極小のドリフト量しか含まれなくなる。次に、発光素子8に発光を切り換え、同様に参照信号を測定し、測距信号と参照信号の位相差をとれば、上述の計算により、既知の固定位相ドリフトのみが残り、原因不明な位相ドリフトφX1,φX2は全て除去されるので、本実施例の光波距離計に生じる測距値誤差は大幅に低減される。 According to the present embodiment, the two light emitting elements 6 and 8 are selectively made to emit light so that the phase of the ranging signal and the reference signal can be measured, respectively, and the above various phase drifts are followed. By intentionally using Δf1x having a phase as a pacing signal for the first PLL control circuit 100 and inputting the PLL circuit output signal f1 + Δf1 to the frequency converter 48 and the frequency converter 68, the light emitting element 6 When the distance is measured by emitting light, the phase drift of the distance measurement signal is substantially removed via the frequency converter 48 of the light receiving unit 301 and the frequency converter 68 of the light receiving unit 401, and then measured by the A / D converters 50 and 70. The phase drift of the ranging signal to be performed includes only a minimal drift amount. Next, if the light emission is switched to the light emitting element 8 and the reference signal is measured in the same manner and the phase difference between the distance measurement signal and the reference signal is taken, only the known fixed phase drift remains, and the unknown phase remains. Since all the drifts φ X1 and φ X2 are eliminated, the distance measurement value error generated in the light wave rangefinder of this embodiment is greatly reduced.

実際に、図3に本実施例における光波距離計で得た測距値を、図4に従来の光波距離計で得た測距値を示す。図3,図4ともに、横軸に温度[℃]、縦軸に測距値[m]を表しており、0mを基準として温度0℃〜45℃の範囲の測距値を示している。図3,図4において、測距値ドリフト(測距値の最大値と最小値との差)を比較すると、従来の光波距離計の測距値ドリフトは0.002m(2mm)であるのに対し、本実施例における光波距離計の測距値ドリフトは0.001m(1mm)であることが判る。よって、本実施例における光波距離計は、様々な位相ドリフトが大幅に低減されたことにより、従来の光波距離計よりも測距値誤差が減り、より正確な測距値が得られることが証明された。   Actually, FIG. 3 shows a distance measurement value obtained by the light wave distance meter in this embodiment, and FIG. 4 shows a distance measurement value obtained by a conventional light wave distance meter. 3 and 4, the horizontal axis represents the temperature [° C.] and the vertical axis represents the distance measurement value [m], and the distance measurement value in the temperature range of 0 ° C. to 45 ° C. with 0 m as a reference. 3 and 4, when the distance value drift (difference between the maximum value and the minimum value of the distance value) is compared, the distance value drift of the conventional optical rangefinder is 0.002 m (2 mm). On the other hand, it can be seen that the distance value drift of the optical wave distance meter in the present embodiment is 0.001 m (1 mm). Therefore, it is proved that the optical distance meter in the present embodiment has a reduced range error and a more accurate distance value than the conventional optical distance meter because various phase drifts are greatly reduced. It was done.

また、特許文献2では、2つの発光素子に、異なる2種類の送光信号(f,f)及び(f-△f,f-△f)が用意されており、測距時に電波干渉して送光信号同士が相互に漏れこみ、測距値誤差の一因になるという問題があったが、本実施例における光波距離計では、送光信号は1種類(f,f)しか用意しないため、電波干渉による上記誤差は生じない。 In Patent Document 2, the two light emitting elements, two different types of light-sending signals (f 1, f 2) and (f 1 - △ f 1, f 2 - △ f 2) are prepared, measured There was a problem that the transmitted light signals leaked to each other due to radio wave interference at a distance, which contributed to a distance measurement value error. However, in the lightwave distance meter in this embodiment, there is one type of transmitted signal (f 1 , F 2 ) are prepared, and the above error due to radio wave interference does not occur.

さらに、特許文献2では、A/D変換器に入力される信号には周波数が異なる複数の中間周波信号があるため、これらをデジタルフィルタで分離している。しかし、プリズム測距の場合、測距光が大気の揺らぎの影響でプリズム視準位置が時折ずれ、振幅変調と同じ影響を受ける。その変調周波数は数Hz〜数kHzにまで及ぶため、A/D変換器に入力した測距光の周波数と参照光の周波数が近接(数kHz程度の差)していると、大気の揺らぎの影響で参照信号に測距信号が合成され、参照信号に測定誤差がおこる問題があるが、本願発明では、A/D変換器に入力する中間周波信号は1種類しかないため、これを原因とする誤差も生じない。   Furthermore, in Patent Document 2, since a signal input to the A / D converter includes a plurality of intermediate frequency signals having different frequencies, these are separated by a digital filter. However, in the case of prism distance measurement, the distance collimated light is sometimes shifted due to the influence of atmospheric fluctuations, and is affected by the same effect as amplitude modulation. Since the modulation frequency ranges from several Hz to several kHz, if the frequency of the ranging light input to the A / D converter and the frequency of the reference light are close (difference of about several kHz), the fluctuation of the atmosphere Due to the influence, the ranging signal is combined with the reference signal, and there is a problem that a measurement error occurs in the reference signal. However, in the present invention, there is only one type of intermediate frequency signal input to the A / D converter. No error occurs.

図5は、本願発明の第2の実施例に係る光波距離計のブロック図である。第2の実施例では、最も大きい周波数のF1よりも低い周波数のF2に係る信号F2+△f2を、周波数生成回路19ではなく第2のPLL制御回路200により生成し、信号F2のLocal信号を、信号F1と共通の発振器(回路内発振器12)を用いずに生成する構成となっている。その他の構成は、第1の実施例と同様である。   FIG. 5 is a block diagram of a lightwave distance meter according to a second embodiment of the present invention. In the second embodiment, the signal F2 + Δf2 related to F2 having a frequency lower than F1 having the highest frequency is generated by the second PLL control circuit 200 instead of the frequency generating circuit 19, and the Local signal of the signal F2 is The signal F1 and the common oscillator (in-circuit oscillator 12) are used without being generated. Other configurations are the same as those of the first embodiment.

図5において、分周部15では、F1を分周して周波数△f2を生成し、第2のPLL制御回路200へ比較用の固定周波数信号として入力する。第2のPLL制御回路200は、位相比較器16,ループフィルタ17,回路内発振器18と、回路内発振器18からのPLL回路出力信号F2+△f2及び周波数発振器1からの固定周波数信号F1が入力されて低周波信号△f2を位相比較器16に出力する第2回路用ミキサー91を備えており、回路内発振器18のPLL回路出力信号を安定させることができる。   In FIG. 5, the frequency divider 15 divides F <b> 1 to generate a frequency Δf <b> 2 and inputs the frequency Δf <b> 2 as a fixed frequency signal for comparison to the second PLL control circuit 200. The second PLL control circuit 200 receives the phase comparator 16, the loop filter 17, the in-circuit oscillator 18, the PLL circuit output signal F2 + Δf2 from the in-circuit oscillator 18 and the fixed frequency signal F1 from the frequency oscillator 1. The second circuit mixer 91 for outputting the low frequency signal Δf2 to the phase comparator 16 is provided, and the PLL circuit output signal of the in-circuit oscillator 18 can be stabilized.

第1の実施例では、信号F2と信号F1で共通の回路内発振器12を使用するため、信号F2においても、位相φ , φ は信号F1についての位相となり、信号F2本来の位相ドリフトよりも大きなドリフトが残ることから、φ, φ も測定し、式(13)から位相φ , φを除去する必要があった。しかし、信号F1よりも周波数が低い信号F2では、発光素子6,8、受光素子40,60の位相ドリフトが信号F1よりも当然に少ないという周知の事実から、信号F2には、別個の発振器を用いたほうが、顕れる位相ドリフトが小さくなる。 In the first embodiment, since the common in-circuit oscillator 12 is used for the signal F2 and the signal F1, the phases φ 1 and φ 2 are also the phases for the signal F1 in the signal F2, and from the original phase drift of the signal F2 Therefore, it was necessary to measure φ B and φ D and remove the phases φ 1 and φ 2 from the equation (13). However, the signal F2 having a frequency lower than that of the signal F1 has a known fact that the phase drift of the light emitting elements 6 and 8 and the light receiving elements 40 and 60 is naturally less than that of the signal F1, so that a separate oscillator is used for the signal F2. When used, the apparent phase drift becomes smaller.

本実施例によれば、別個に第2のPLL制御回路200を設けたことで、信号F2には信号F1の位相ドリフトは含まれず、かつ顕れる位相ドリフトが小さいため、さらに測距値誤差を低減することができる。   According to the present embodiment, since the second PLL control circuit 200 is separately provided, the signal F2 does not include the phase drift of the signal F1, and the apparent phase drift is small, thereby further reducing the distance measurement value error. can do.

また、φ, φ,を測定しなくとも、 式(6)からφ, φと同様にφ, φを得ることができることから、信号F2,F1ともにφ, φを測定しなくとも良いことから、測定時間が短縮される。 Also, φ B, φ D, even without measuring, A phi from equation (6), φ C as well as phi B, since it is possible to obtain a phi D, the signal F2, F1 both phi B, the phi D Since it is not necessary to measure, the measurement time is shortened.

なお、本願発明は、前記第1及び第2の実施例に限るものではなく、例えば、光波距離計を内蔵した測量機、例えばトータルステーションや、その他の距離測定装置等にも広く利用できる。   The present invention is not limited to the first and second embodiments, and can be widely used for, for example, a surveying instrument having a built-in lightwave distance meter, for example, a total station or other distance measuring devices.

1 周波数発振器
4 発光切換回路(発光切換手段)
6 第1の発光素子
8 第2の発光素子
13 設定用ミキサー
14 信号切換回路
22 目標反射物
21、23 測距光路
26、29、31 参照光路
40 第1の受光素子
60 第2の受光素子
42、45、48、62、65、68 周波数変換器
44、47、50、64、67、70 A/D変換器
80 演算処理部
100 第1のPLL制御回路
200 第2のPLL制御回路
300 第1の受光部
400 第2の受光部
1 Frequency oscillator 4 Light emission switching circuit (light emission switching means)
6 First light-emitting element 8 Second light-emitting element 13 Setting mixer 14 Signal switching circuit 22 Target reflector 21, 23 Distance optical path 26, 29, 31 Reference optical path 40 First light-receiving element 60 Second light-receiving element 42 , 45, 48, 62, 65, 68 Frequency converters 44, 47, 50, 64, 67, 70 A / D converter 80 Arithmetic processing unit 100 First PLL control circuit 200 Second PLL control circuit 300 First Second light receiving portion 400

Claims (3)

周波数発振器より生成された周波数信号を大きさの異なる複数の変調周波数に変調された光として出射する第1の発光素子及び第2の発光素子と、前記両発光素子から出射された光を受光する第1の受光素子及び第2の受光素子と、前記第1の受光素子に接続され、周波数変換器を含む第1の受光部と、前記第2の受光素子に接続され、周波数変換器を含む第2の受光部と、を備え、
前記第1の発光素子及び第2の発光素子は、発光切換手段によって交互に切り換えられて択一的に発光し、
第1の発光素子から出射された光は2つに分けられ、一方は測距光として目標反射物までを往復する測距光路を経て第1の受光素子に入射し、他方は参照光として第1の参照光路を経て第2の受光素子に入射し、
第2の発光素子から出射された光は2つに分けられ、一方は参照光として第2の参照光路を経て第2の受光素子に入射し、他方は参照光として第3の参照光路を経て第1の受光素子に入射し、
前記第2の受光部を経た中間周波信号が帰還され、整調用信号としてPLL制御回路に入力され、該PLL制御回路において、前記周波数発振器から比較用に分周された固定周波数信号と前記整調用信号とが位相比較されフィルタ平滑後の電圧で発振された周波数がPLL回路出力信号として再出力され、
前記PLL回路出力信号が、前記第1の受光部及び第2の受光部の周波数変換器に入力され、それぞれA/D変換器で測定されてデジタルデータに変換され、演算処理部において、前記択一的発光により得られた測距信号と第1の参照信号の位相差と第3の参照信号と第2の参照信号の位相差との差から目標反射物までの測距値を算出する光波距離計。
A first light emitting element and a second light emitting element that emit a frequency signal generated by a frequency oscillator as light modulated to a plurality of modulation frequencies having different sizes, and light emitted from both the light emitting elements is received. A first light receiving element and a second light receiving element; a first light receiving unit connected to the first light receiving element and including a frequency converter; and a second light receiving element connected to the second light receiving element and including a frequency converter. A second light receiving unit,
The first light emitting element and the second light emitting element are alternately switched by a light emission switching means to selectively emit light,
The light emitted from the first light emitting element is divided into two, one of which enters the first light receiving element as a distance measuring light through a distance measuring optical path that reciprocates to the target reflector, and the other as the reference light. 1 is incident on the second light receiving element via the reference optical path,
The light emitted from the second light emitting element is divided into two parts, one of which enters the second light receiving element through the second reference light path as the reference light, and the other through the third reference light path as the reference light. Incident on the first light receiving element,
The intermediate frequency signal that has passed through the second light-receiving unit is fed back and input to the PLL control circuit as a pacing signal. In the PLL control circuit, the fixed frequency signal divided from the frequency oscillator for comparison and the pacing signal The signal is phase-compared and the frequency oscillated with the smoothed voltage is re-output as the PLL circuit output signal,
The PLL circuit output signal is input to the frequency converters of the first light receiving unit and the second light receiving unit, each measured by an A / D converter and converted into digital data. A light wave for calculating a distance measurement value to the target reflector from the difference between the phase difference between the distance measurement signal and the first reference signal and the phase difference between the third reference signal and the second reference signal obtained by single light emission. Distance meter.
前記PLL制御回路に、前記PLL回路出力信号及び前記周波数発振器からの固定周波数信号が入力されて低周波信号を出力する設定用ミキサーと、前記演算処理部の指令により、前記設定用ミキサーからの低周波信号又は前記整調用信号のいずれか一方を選択的に該PLL制御回路に出力する信号切換手段が設けられ、前記信号切換手段は、前記光波距離計内部の初期設定時には前記低周波信号が、光波距離計内部の増幅度が決定された後は前記整調用信号が出力されるよう構成されたことを特徴とする請求項1に記載の光波距離計。 A setting mixer that outputs a low frequency signal when the PLL circuit output signal and the fixed frequency signal from the frequency oscillator are input to the PLL control circuit, and a low frequency signal from the setting mixer according to a command from the arithmetic processing unit. A signal switching means for selectively outputting either the frequency signal or the pacing signal to the PLL control circuit is provided, and the signal switching means is configured so that the low-frequency signal is initially set in the optical distance meter, The lightwave distance meter according to claim 1, wherein the pacing signal is output after the amplification degree in the lightwave distance meter is determined . 前記大きさの異なる複数変調周波数のうち、
最も周波数の大きい第1周波数には、前記整調用信号が入力される前記PLL制御回路が用られ、
前記第1周波数より周波数の低い第2周波数には、前記周波数発振器からの固定周波数信号が入力される第2回路用ミキサーを備えた第2のPLL制御回路が設けられたことを特徴とする請求項1又は2に記載の光波距離計。
Among the plurality of modulation frequencies having different sizes,
For the first frequency having the largest frequency, the PLL control circuit to which the pacing signal is input is used.
The second PLL control circuit including a second circuit mixer to which a fixed frequency signal from the frequency oscillator is input is provided at a second frequency lower than the first frequency. Item 3. A light wave distance meter according to item 1 or 2.
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