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JP2016090436A - Time-of-flight optical ranging device - Google Patents

Time-of-flight optical ranging device Download PDF

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JP2016090436A
JP2016090436A JP2014226070A JP2014226070A JP2016090436A JP 2016090436 A JP2016090436 A JP 2016090436A JP 2014226070 A JP2014226070 A JP 2014226070A JP 2014226070 A JP2014226070 A JP 2014226070A JP 2016090436 A JP2016090436 A JP 2016090436A
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light
light receiving
distance
receiving slot
phase
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JP6455088B2 (en
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光宏 清野
Mitsuhiro Kiyono
光宏 清野
柳井　謙一
Kenichi Yanai
謙一 柳井
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Denso Corp
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Abstract

PROBLEM TO BE SOLVED: To maintain required ranging accuracy even in long distance ranging while eliminating an increase of light emission intensity and avoiding the use of a large device.SOLUTION: A time-of-flight ranging device 1 has a photoreception slot indemnification unit 6a that identifies a photoreception slot that received return light upon emission of modulated light, and a phase-based TOF measurement unit 6b that measures phase difference between the modulated light and the return light. A precise distance from a host device to a target object is calculated and determined by first measuring a rough distance, which can be long, from the host device to the target object using the photoreception slot identification unit, and then measuring a phase difference within one cycle of the photoreception slots using the phase-based TOF measurement unit.SELECTED DRAWING: Figure 1

Description

本発明は、変調光を空間に発光し、変調光が対象物で反射した戻り光を含む入射光を受光して電荷を蓄積し、その電荷の蓄積状態に基づいて変調光と戻り光との間の位相差を計測し、自装置から対象物までの距離を計算して取得する光飛行型測距装置に関する。   The present invention emits modulated light into a space, receives incident light including return light reflected by an object, accumulates charges, and based on the accumulated state of the charges, The present invention relates to an optical flight-type distance measuring device that measures a phase difference between them and calculates and obtains a distance from its own device to an object.

従来より、変調光（測距光）を空間に発光し、変調光が対象物で反射した戻り光（反射光）を含む入射光を受光して電荷を蓄積し、その電荷の蓄積状態に基づいて変調光と戻り光との間の位相差を計測し、自装置から対象物までの距離を計算して取得する光飛行（ＴＯＦ：Time of Flight）型測距装置が供されている。近年では、複数の変調周波数を用いた位相差の計測を組み合わせることで、高精度且つ２π以上の遠距離測距に対応する技術も供されている（例えば特許文献１、２参照）。   Conventionally, modulated light (ranging light) is emitted into space, incident light including return light (reflected light) reflected by the object is received, charges are accumulated, and the charge is accumulated based on the accumulated state. Thus, a time-of-flight (TOF) type distance measuring device is provided that measures the phase difference between the modulated light and the return light and calculates and obtains the distance from the device to the object. In recent years, there has also been provided a technology that supports high-precision long-distance ranging of 2π or more by combining measurement of phase differences using a plurality of modulation frequencies (see, for example, Patent Documents 1 and 2).

米国特許第８６２９９７６号明細書U.S. Pat. No. 8,629,976 米国特許出願公開第２０１４／００４９７６７号明細書US Patent Application Publication No. 2014/0049767

しかしながら、必要な距離精度を維持したまま、車載要求の遠距離測距（例えば数１０ｍ程度）を行うには、発光強度（発光時間と発光ピークパワーとの積）を高める必要がある。そのため、大電力の光源を用いる構成や複数の光源を並列接続する構成が必要となり、装置全体の体格が大きくなってしまうという問題がある。   However, in order to perform a long-distance ranging (for example, about several tens of meters) required for in-vehicle use while maintaining the necessary distance accuracy, it is necessary to increase the emission intensity (product of emission time and emission peak power). For this reason, a configuration using a high-power light source or a configuration in which a plurality of light sources are connected in parallel is required, and there is a problem that the overall size of the apparatus becomes large.

本発明は、上記した事情に鑑みてなされたものであり、その目的は、発光強度を高めることを不要として装置全体の大型化を回避しつつ、遠距離測距でも必要な距離精度を維持することができる光飛行型測距装置を提供することにある。   The present invention has been made in view of the above-described circumstances, and an object of the present invention is to maintain the necessary distance accuracy even in long-distance ranging while avoiding an increase in the size of the entire apparatus without increasing the emission intensity. It is an object of the present invention to provide an optical flight type distance measuring device capable of performing the above.

請求項１に記載した発明によれば、発光手段は、変調光を空間に発光する。受光手段は、発光手段から発光された変調光が対象物で反射した戻り光を含む入射光を受光して電荷を蓄積する。発光制御手段は、発光手段の発光動作を制御する。受光制御手段は、受光手段の受光動作を制御する。受光スロット特定手段は、変調光が発光手段から発光された時点を基点とする所定時間間隔の距離スロットのうち戻り光が受光手段に受光された距離スロットを受光スロットとして特定する。位相型ＴＯＦ計測手段は、受光手段における電荷の蓄積状態に基づいて変調光と戻り光との間の位相差を計測する。距離取得手段は、受光スロット特定手段による特定結果と位相型ＴＯＦ計測手段による計測結果とを組み合わせることで、自装置から対象物までの距離を計算して取得する。   According to the first aspect of the present invention, the light emitting means emits the modulated light in space. The light receiving means receives incident light including the return light reflected by the object from the modulated light emitted from the light emitting means, and accumulates charges. The light emission control means controls the light emission operation of the light emission means. The light receiving control means controls the light receiving operation of the light receiving means. The light receiving slot specifying means specifies, as a light receiving slot, a distance slot in which the return light is received by the light receiving means among distance slots of a predetermined time interval starting from the time when the modulated light is emitted from the light emitting means. The phase-type TOF measurement unit measures the phase difference between the modulated light and the return light based on the charge accumulation state in the light receiving unit. The distance acquisition means calculates and acquires the distance from the own apparatus to the object by combining the specification result by the light receiving slot specification means and the measurement result by the phase-type TOF measurement means.

戻り光が受光された受光スロットを特定する方法は、高い分解能で距離を特定できなかったり、高範囲（高解像度）をカバーできなかったりする点で不利であるが、位相回りの発生を回避できたり、マルチパスやミックスドピクセルの影響を除去できたりする点で有利である。一方、変調光と戻り光との間の位相差を計測する方法は、位相回りが発生したり、マルチパスやミックスドピクセルの影響を受ける点で不利であるが、高い分解能で距離を特定できたり、高範囲をカバーできたりする点で有利である。   The method of identifying the receiving slot where the return light is received is disadvantageous in that it cannot identify the distance with high resolution or cannot cover the high range (high resolution), but it can avoid the occurrence of phase rotation. Or the influence of multi-pass and mixed pixels can be removed. On the other hand, the method of measuring the phase difference between the modulated light and the return light is disadvantageous in that phase rotation occurs and it is affected by multi-pass and mixed pixels, but the distance can be specified with high resolution. It is advantageous in that it can cover a high range.

本発明では、受光スロット特定手段による特定結果と位相型ＴＯＦ計測手段による計測結果とを組み合わせることで、それぞれの方法による利点を両立する。即ち、受光スロット特定では、変調光の発光波形のデューティーを従来の５０％よりも短くし（低デューティー化し）、その分、発光ピークパワーを高めることで、遠距離まで受光スロットを特定する。位相型ＴＯＦ計測では、変調光の発光波形のデューティーを従来の５０％よりも短くする、又は従来の５０％のままとし、受光スロットの１周期内での位相差を計測する。このように受光スロット特定により自装置から対象物までの大まかな距離を遠距離まで計測し、位相型ＴＯＦ計測により受光スロットの１周期内での位相差を計測することで、自装置から対象物までの詳細な距離を計算して取得することできる。これにより、発光強度を高めることを不要として装置全体の大型化を回避しつつ、遠距離測距でも必要な距離精度を維持することができる。   In the present invention, by combining the identification result by the light receiving slot identification unit and the measurement result by the phase-type TOF measurement unit, the advantages of the respective methods can be achieved. That is, in specifying the light receiving slot, the duty of the light emission waveform of the modulated light is made shorter than the conventional 50% (lower duty), and the light emission peak power is increased accordingly, thereby specifying the light receiving slot up to a long distance. In the phase-type TOF measurement, the duty of the emission waveform of the modulated light is made shorter than the conventional 50%, or is kept at the conventional 50%, and the phase difference within one period of the light receiving slot is measured. In this way, by measuring the rough distance from the own device to the object by specifying the light receiving slot, and measuring the phase difference within one period of the light receiving slot by the phase-type TOF measurement, the object from the own device is measured. It is possible to calculate and obtain a detailed distance up to. Thereby, it is possible to maintain the required distance accuracy even in long-distance ranging while avoiding the increase in the size of the entire apparatus without increasing the emission intensity.

本発明の第１の実施形態を示す機能ブロック図Functional block diagram showing a first embodiment of the present invention 発光波形を示す図Diagram showing light emission waveform 受光素子の構成を示す機能ブロック図Functional block diagram showing the configuration of the light receiving element バイナリコードを用いて受光スロットを特定する態様を示す図（その１）The figure which shows the aspect which identifies a light-receiving slot using a binary code (the 1) グレイコードを用いて受光スロットを特定する態様を示す図（その１）The figure which shows the aspect which identifies a light-receiving slot using a Gray code | cord | chord (the 1) バイナリコードを用いて受光スロットを特定する態様を示す図（その２）FIG. 2 is a diagram showing a mode of specifying a light receiving slot using a binary code (part 2) グレイコードを用いて受光スロットを特定する態様を示す図（その２）The figure which shows the aspect which identifies a light-receiving slot using a gray code (the 2) タイミングチャートTiming chart フローチャートflowchart 露光パターンを示す図（その１）Drawing showing exposure pattern (1) 露光パターンを示す図（その２）Drawing showing exposure pattern (2) 受光スロット特定と位相型ＴＯＦ計測の組み合わせを示す図Diagram showing combination of light receiving slot identification and phase-type TOF measurement 距離スロットの時間間隔と位相型ＴＯＦ計測の周期との関係を示す図（その１）The figure which shows the relationship between the time interval of a distance slot, and the period of phase type TOF measurement (the 1) 距離スロットの時間間隔と位相型ＴＯＦ計測の周期との関係を示す図（その２）The figure which shows the relationship between the time interval of a distance slot, and the period of phase type TOF measurement (the 2) 受光スロット特定と位相型ＴＯＦ計測との関係を概念的に示す図（その１）A diagram conceptually showing the relationship between light-receiving slot identification and phase-type TOF measurement (Part 1) 受光スロット特定と位相型ＴＯＦ計測との関係を概念的に示す図（その２）A diagram conceptually showing the relationship between light receiving slot identification and phase-type TOF measurement (Part 2) 本発明の第２の実施形態を示す機能ブロック図Functional block diagram showing a second embodiment of the present invention

（第１の実施形態）
以下、本発明を、車両に搭載可能な光飛行型測距装置に適用した第１の実施形態について図１から図１６を参照して説明する。光飛行型測距装置が車両に搭載される態様はどのような態様でも良い。例えば光飛行型測距装置１が車両の前方部及び後方部に搭載される態様では、車両の前方及び後方が対象物（例えば人、他の車両、壁等）の監視エリアとなる。光飛行型測距装置１は、１個の受光素子が１画素として構成されているセンサであり、所定の発光周波数（例えば２０ＭＨｚ）の変調光（測距光）を空間に発光する（照射する）。変調光が発光された空間に対象物が存在すると、変調光が対象物で反射した戻り光（反射光）を含む入射光が光飛行型測距装置１に受光される。 (First embodiment)
A first embodiment in which the present invention is applied to an optical flight type distance measuring device that can be mounted on a vehicle will be described below with reference to FIGS. The mode in which the optical flight type distance measuring device is mounted on the vehicle may be any mode. For example, in a mode in which the optical flight type distance measuring device 1 is mounted on the front part and the rear part of the vehicle, the front and rear of the vehicle are monitoring areas for objects (for example, people, other vehicles, walls, etc.). The optical flight type distance measuring device 1 is a sensor in which one light receiving element is configured as one pixel, and emits (irradiates) modulated light (ranging light) having a predetermined light emission frequency (for example, 20 MHz) into space. ). When an object is present in the space where the modulated light is emitted, incident light including return light (reflected light) reflected by the object is received by the optical flight rangefinder 1.

光飛行型測距装置１は、制御部２と、発光部３（発光手段）と、受光部４（受光手段）とを有する。制御部２は、発光部３の発光動作を制御する発光制御回路５（発光制御手段）と、受光部４の受光動作を制御する受光制御回路６（受光制御手段）と、記憶部７とを有する。受光制御回路６は、受光スロット特定部６ａ（受光スロット特定手段）と、位相型ＴＯＦ計測部６ｂ（位相型ＴＯＦ計測手段）と、距離取得部６ｃ（距離取得手段）とを有する。制御部２は、マイクロコンピュータを有しており、制御プログラムを実行することで、発光部３の発光動作や受光部４の受光動作等を制御する処理を行う。   The optical flight type distance measuring device 1 includes a control unit 2, a light emitting unit 3 (light emitting unit), and a light receiving unit 4 (light receiving unit). The control unit 2 includes a light emission control circuit 5 (light emission control unit) that controls the light emission operation of the light emitting unit 3, a light reception control circuit 6 (light reception control unit) that controls the light reception operation of the light receiving unit 4, and the storage unit 7. Have. The light receiving control circuit 6 includes a light receiving slot specifying unit 6a (light receiving slot specifying unit), a phase type TOF measuring unit 6b (phase type TOF measuring unit), and a distance acquiring unit 6c (distance acquiring unit). The control unit 2 includes a microcomputer, and performs processing for controlling the light emitting operation of the light emitting unit 3 and the light receiving operation of the light receiving unit 4 by executing a control program.

発光部３は、光源としての発光素子８と、発光素子８を駆動する駆動回路９とを有する。駆動回路９は、発光制御回路５から発光指令信号を入力すると、発光指令を発光素子８に出力する。発光素子８は、例えばＬＥＤ（Light Emitting Diode）やレーザ等の高速変調（高速点滅）が可能なデバイスから構成されている。発光素子８は、駆動回路９から発光指令を入力すると、駆動回路９から供給される電力を動作電力として駆動し、変調光を予め設定されている空間に発光する。   The light emitting unit 3 includes a light emitting element 8 as a light source and a drive circuit 9 that drives the light emitting element 8. When the light emission command signal is input from the light emission control circuit 5, the drive circuit 9 outputs the light emission command to the light emitting element 8. The light emitting element 8 is composed of a device capable of high-speed modulation (high-speed blinking) such as an LED (Light Emitting Diode) or a laser. When a light emission command is input from the drive circuit 9, the light emitting element 8 is driven using the power supplied from the drive circuit 9 as operating power, and emits modulated light in a preset space.

発光制御回路５は、図２に示すように、発光素子８から発光させる変調光の発光波形のデューティーを切替可能となっている。具体的には、発光制御回路５は、発光波形のデューティーを５０％として変調光を発光素子８から発光させる期間と、発光波形のデューティーを６．２５％として変調光を発光素子８から発光させる期間とを切替可能となっている。発光制御回路５は、発光波形のデューティーを６．２５％とする（低デューティー化する）ときには、従来の（発光波形のデューティーを５０％とするときの）８倍の発光ピークパワーで変調光を発光素子８から発光させる（Ｐ２＝８×Ｐ１）。尚、発光波形のデューティーを５０％とした場合と、発光波形のデューティーを６．２５％として発光ピークパワーを８倍とした場合とでは、発光強度がエネルギー（熱）的に等価であるので、回路規模や放熱対策は従来と同等のままで済む。即ち、ハードウェアの改良を必要とせずに、低デューティー化して発光ピークパワーを高めることで、遠距離までの測距が可能になると共に、外乱光に対するＳＮＲ（信号対雑音比）も向上して距離精度が高まる。加えて、発光素子８を駆動する駆動回路９でもデューティーを短くすることによる温度条件の緩和で電流ロスが少なくなり、発光ピークパワーがより一層高まる。   As shown in FIG. 2, the light emission control circuit 5 can switch the duty of the light emission waveform of the modulated light emitted from the light emitting element 8. Specifically, the light emission control circuit 5 emits the modulated light from the light emitting element 8 by setting the duty of the light emission waveform to 50% and emitting the modulated light from the light emitting element 8 and the duty of the light emission waveform to 6.25%. The period can be switched. When the duty of the light emission waveform is set to 6.25% (to reduce the duty), the light emission control circuit 5 outputs the modulated light with the light emission peak power of 8 times the conventional (when the duty of the light emission waveform is set to 50%). Light is emitted from the light emitting element 8 (P2 = 8 × P1). Since the emission waveform duty is 50% and the emission waveform duty is 6.25% and the emission peak power is 8 times, the emission intensity is equivalent in energy (heat). The circuit scale and heat dissipation measures remain the same as before. In other words, by increasing the emission peak power by reducing the duty without requiring hardware improvements, it is possible to measure distances up to long distances and improve the SNR (signal-to-noise ratio) for ambient light. Distance accuracy increases. In addition, the drive circuit 9 for driving the light emitting element 8 also reduces the current loss due to the relaxation of the temperature condition by shortening the duty, and the light emission peak power is further increased.

受光部４は、選択回路１０と、縦方向のラインを構成する複数の受光素子群１１ａ〜１１ｎとを有する。選択回路１０は、受光制御回路６から受光指令信号を入力すると、受光指令を各受光素子群１１ａ〜１１ｎに出力する。又、選択回路１０は、受光制御回路６から読出指令信号を入力すると、読出指令を各受光素子群１１ａ〜１１ｎに出力する。各受光素子群１１ａ〜１１ｎは、選択回路１０から受光指令を入力すると、発光素子８から発光された変調光が対象物で反射した戻り光を含む入射光の受光を待機する（受光不可能な状態から受光可能な状態へと移行する）。各受光素子群１１ａ〜１１ｎは、規則的に配列されている複数の受光素子１２ａ〜１２ｎを有する。   The light-receiving unit 4 includes a selection circuit 10 and a plurality of light-receiving element groups 11a to 11n that form vertical lines. When receiving the light reception command signal from the light reception control circuit 6, the selection circuit 10 outputs the light reception command to each of the light receiving element groups 11a to 11n. Further, when the selection circuit 10 receives a read command signal from the light reception control circuit 6, the selection circuit 10 outputs the read command to each of the light receiving element groups 11a to 11n. When each light receiving element group 11a to 11n receives a light reception command from the selection circuit 10, the light receiving element group 11a to 11n waits for reception of incident light including return light reflected from the object by the modulated light emitted from the light emitting element 8 (cannot receive light). Transition from a state to a state where light can be received). Each of the light receiving element groups 11a to 11n includes a plurality of light receiving elements 12a to 12n regularly arranged.

各受光素子１２ａ〜１２ｎは、図３に示すように、光電変換素子１３と、電荷蓄積部１４とを有する。光電変換素子１３は、変調光が対象物で反射した戻り光を含む入射光を受光すると、その受光した入射光を受光量に応じた電荷に変換する。電荷蓄積部１４は、第１〜第４の４個の単位蓄積部１５ａ〜１５ｄを有し、光電変換素子１３により変換された電荷を変調光の変調周期（１フレームの周期）に同期して振り分ける。そして、電荷蓄積部１４は、その振り分けた電荷をそれぞれ第１〜第４の単位蓄積部１５ａ〜１５ｄに蓄積する。   As shown in FIG. 3, each of the light receiving elements 12 a to 12 n includes a photoelectric conversion element 13 and a charge accumulation unit 14. When the photoelectric conversion element 13 receives incident light including the return light reflected by the object, the photoelectric conversion element 13 converts the received incident light into an electric charge corresponding to the amount of light received. The charge storage unit 14 includes first to fourth unit storage units 15a to 15d, and the charge converted by the photoelectric conversion element 13 is synchronized with the modulation period (period of one frame) of the modulated light. Distribute. The charge storage unit 14 stores the distributed charges in the first to fourth unit storage units 15a to 15d, respectively.

又、各受光素子群１１ａ〜１１ｎは、選択回路１０から読出指令を入力すると、各受光素子１２ａ〜１２ｎの第１〜第４の単位蓄積部１５ａ〜１５ｄに蓄積されている電荷の電荷量（受光量）を受光制御回路６に出力する。受光制御回路６は、読出指令を所定の時間間隔で選択回路１０に出力し、第１〜第４の単位蓄積部１５ａ〜１５ｄに蓄積されている電荷の電荷量を所定の時間間隔で読み出す。そして、受光制御回路６は、その読み出した電荷の電荷量を用いて、戻り光が受光された距離スロットである受光スロットの特定（受光スロット特定）を受光スロット特定部６ａにより行ったり、変調光と戻り光との間の位相差の計測（位相型ＴＯＦ計測）を位相型ＴＯＦ計測部６ｂにより行ったりする。   Further, when each light receiving element group 11a to 11n receives a read command from the selection circuit 10, the amount of charge accumulated in the first to fourth unit accumulating units 15a to 15d of each light receiving element 12a to 12n ( (Amount of received light) is output to the received light control circuit 6. The light reception control circuit 6 outputs a read command to the selection circuit 10 at a predetermined time interval, and reads out the charge amounts of the charges accumulated in the first to fourth unit accumulation units 15a to 15d at a predetermined time interval. The light receiving control circuit 6 uses the light amount of the read charge to specify the light receiving slot (light receiving slot specifying) which is a distance slot in which the return light is received by the light receiving slot specifying unit 6a, or to modulate light. The phase difference between the return light and the return light (phase-type TOF measurement) is measured by the phase-type TOF measurement unit 6b.

受光スロット特定部６ａは、変調光が発光素子８から発光された時点を基点とする所定時間間隔の距離スロットのうち戻り光（最大強度の戻り光）が受光部４に受光された距離スロットを受光スロットとして特定する。このとき、発光制御回路５は、発光波形のデューティーを６．２５％とし、発光ピークパワーを発光波形のデューティーが５０％のときの８倍として変調光を発光素子８から発光させる。受光スロット特定部６ａは、距離スロットの個数に対してバイナリコードやグレイコードを用いてサンプル数を最小化し、各サンプルについて電圧値の大小を判定することで、受光スロットを特定する。受光スロット特定部６ａは、電圧値の差が規定値以上である期間では「１」を割当て、電圧値の差が規定値未満である期間では「０」を割当てる。   The light receiving slot specifying unit 6 a is a distance slot in which the return light (return light with the maximum intensity) is received by the light receiving unit 4 among the distance slots with a predetermined time interval starting from the time when the modulated light is emitted from the light emitting element 8. It is specified as a light receiving slot. At this time, the light emission control circuit 5 causes the light emitting element 8 to emit modulated light by setting the duty of the light emission waveform to 6.25% and the light emission peak power to eight times that when the duty of the light emission waveform is 50%. The light receiving slot specifying unit 6a specifies the light receiving slot by minimizing the number of samples using binary code or gray code with respect to the number of distance slots and determining the magnitude of the voltage value for each sample. The light receiving slot specifying unit 6a assigns “1” during a period in which the voltage value difference is greater than or equal to the prescribed value, and assigns “0” in a period in which the voltage value difference is less than the prescribed value.

図４は、距離スロットの個数を「８」とし、サンプル数を「３」とし、バイナリコードのサンプリングパターンを用いて受光スロットを特定する態様を例示している。図４の例示では、戻り光の受光期間が距離スロッ３から距離スロット４への変化タイミングに重なっており、受光スロット特定部６ａは、バイナリコードを「１，０，１」と特定することで、距離スロット３を受光スロットとして特定する。又、図５は、距離スロットの個数を「８」とし、サンプル数を「３」とし、グレイコードのサンプリングパターンを用いて受光スロットを特定する態様を例示している。図５の例示でも、戻り光の受光期間が距離スロッ３から距離スロット４への変化タイミングに重なっており、受光スロット特定部６ａは、グレイコードを「１，１，１」と特定することで、距離スロット３を受光スロットとして特定する。   FIG. 4 illustrates an example in which the number of distance slots is “8”, the number of samples is “3”, and the light receiving slots are specified using a binary code sampling pattern. In the example of FIG. 4, the light receiving period of the return light overlaps with the change timing from the distance slot 3 to the distance slot 4, and the light receiving slot identifying unit 6 a identifies the binary code as “1, 0, 1”. The distance slot 3 is specified as the light receiving slot. FIG. 5 illustrates an example in which the number of distance slots is set to “8”, the number of samples is set to “3”, and the light receiving slots are specified using the Gray code sampling pattern. In the example of FIG. 5 as well, the light receiving period of the return light overlaps with the change timing from the distance slot 3 to the distance slot 4, and the light receiving slot identifying unit 6 a identifies the gray code as “1, 1, 1”. The distance slot 3 is specified as the light receiving slot.

バイナリコードを用いる方法では、「０」、「１」の変化点がサンプル同士で重複するタイミングが存在する。図４の例示では、例えば距離スロット２から距離スロット３への変化タイミング（ｔ２）では「０」、「１」の変化点がサンプル２、３で重複し、距離スロット４から距離スロット５への変化タイミング（ｔ４）では「０」、「１」の変化点がサンプル１〜３で重複し、距離スロット６から距離スロット７への変化タイミング（ｔ６）では「０」、「１」の変化点がサンプル２、３で重複する。これに対して、グレイコードを用いる方法では、「０」、「１」の変化点がサンプル同士で重複するタイミングが存在しない。このような性質の相違により、グレイコードを用いる場合はバイナリコードを用いる場合よりもロバスト性の点で有利である。   In the method using the binary code, there is a timing at which the change points of “0” and “1” overlap between samples. In the example of FIG. 4, for example, at the change timing (t2) from the distance slot 2 to the distance slot 3, the change points of “0” and “1” overlap in the samples 2 and 3, and the distance slot 4 to the distance slot 5 changes. At the change timing (t4), the change points “0” and “1” overlap in the samples 1 to 3, and at the change timing (t6) from the distance slot 6 to the distance slot 7, the change points “0” and “1”. Are duplicated in samples 2 and 3. On the other hand, in the method using the Gray code, there is no timing at which “0” and “1” change points overlap between samples. Due to the difference in properties, the use of the Gray code is more advantageous in terms of robustness than the use of the binary code.

具体的に説明すると、図６及び図７に示すように戻り光の受光期間が距離スロット４から距離スロット５への変化タイミングに重なるときを想定する。バイナリコードを用いた図６の例示では、受光スロット特定部６ａは、サンプル１〜３を「１，０，０」と特定することで、距離スロット４を受光スロットとして特定する。しかしながら、受光スロット特定部６ａは、例えばサンプル１を「０」と特定してしまい、サンプル１〜３を「０，０，０」と特定してしまうと、距離スロット８を受光スロットとして特定してしまう。即ち、サンプル１〜３のうちサンプル１について「０」、「１」の特定がずれただけでも、受光スロットの特定が距離スロット４から距離スロット８までずれてしまい、受光スロットを特定する誤差が大きい（受光スロットを特定する精度が低い）。サンプル２、３について「０」、「１」の特定がずれた場合も同様である。又、戻り光の受光期間が距離スロット２から距離スロット３への変化タイミングに重なるときや距離スロット６から距離スロット７への変化タイミングに重なるときも同様である。   More specifically, it is assumed that the light receiving period of the return light overlaps with the change timing from the distance slot 4 to the distance slot 5 as shown in FIGS. In the example of FIG. 6 using the binary code, the light receiving slot specifying unit 6a specifies the distance slot 4 as the light receiving slot by specifying the samples 1 to 3 as “1, 0, 0”. However, if the light receiving slot specifying unit 6a specifies the sample 1 as “0” and specifies the samples 1 to 3 as “0, 0, 0”, for example, the light receiving slot specifying unit 6a specifies the distance slot 8 as the light receiving slot. End up. That is, even if the specification of “0” and “1” for sample 1 among samples 1 to 3 is shifted, the specification of the light receiving slot is shifted from the distance slot 4 to the distance slot 8, and there is an error in specifying the light receiving slot. Large (the accuracy of identifying the light receiving slot is low). The same applies to the samples 2 and 3 when “0” and “1” are not specified. The same applies when the light receiving period of the return light overlaps with the change timing from the distance slot 2 to the distance slot 3 or when it overlaps with the change timing from the distance slot 6 to the distance slot 7.

これに対して、グレイコードを用いた図７の例示では、受光スロット特定部６ａは、サンプル１〜３を「１，１，０」と特定することで、距離スロット４を受光スロットとして特定する。この場合、上記と同様に例えばサンプル１を「０」と特定してしまい、サンプル１〜３を「０，１，０」と特定してしまっても、距離スロット４に隣接する距離スロット５を受光スロットとして特定するに止まる。即ち、サンプル１〜３のうちサンプル１について「０」、「１」の特定がずれても、受光スロットの特定が距離スロット４から距離スロット５までに止まり、受光スロットを特定する誤差が小さい（受光スロットを特定する精度が高い）。戻り光の受光期間が別の距離スロットから更に別の距離スロットへの変化タイミングに重なるときも同様である。このようにグレイコードを用いる場合はバイナリコードを用いる場合よりもロバスト性の点で有利である。   On the other hand, in the illustration of FIG. 7 using the gray code, the light receiving slot specifying unit 6a specifies the distance slot 4 as the light receiving slot by specifying the samples 1 to 3 as “1, 1, 0”. . In this case, for example, even if the sample 1 is specified as “0” and the samples 1 to 3 are specified as “0, 1, 0”, the distance slot 5 adjacent to the distance slot 4 is determined as described above. It only needs to be specified as a light receiving slot. That is, even if the specification of “0” and “1” is shifted for sample 1 among samples 1 to 3, the specification of the light receiving slot stops from the distance slot 4 to the distance slot 5 and the error for specifying the light receiving slot is small ( High accuracy to identify the light receiving slot). The same applies when the light receiving period of the return light overlaps with the change timing from another distance slot to another distance slot. Thus, the use of the Gray code is more advantageous in terms of robustness than the use of the binary code.

位相型ＴＯＦ計測部６ｂは、発光制御回路５と連携し、各受光素子１２の第１〜第４の単位蓄積部１５ａ〜１５ｄに蓄積されている電荷の電荷量に基づいて変調光と戻り光との間の位相差を計測する。即ち、図８に示すように、発光制御回路５は、１フレームの周期内の発光期間において、発光指令信号を周期がＴｓ、オン時間がＴｓ／２、オフ時間がＴｓ／２の矩形波として駆動回路９に出力し、発光素子８からのＴｓ／２時間の発光とＴｓ／２時間の発光停止とを繰り返させる。尚、発光制御回路５は、発光指令信号を矩形波で出力することに限らず、発光指令信号を正弦波や鋸波等で出力しても良い。   The phase-type TOF measurement unit 6b cooperates with the light emission control circuit 5, and modulates light and return light based on the amount of charge accumulated in the first to fourth unit accumulation units 15a to 15d of each light receiving element 12. Measure the phase difference between and. That is, as shown in FIG. 8, the light emission control circuit 5 converts the light emission command signal into a rectangular wave having a period of Ts, an on time of Ts / 2, and an off time of Ts / 2 in the light emission period within one frame period. It outputs to the drive circuit 9, and repeats light emission from the light emitting element 8 for Ts / 2 hours and light emission stop for Ts / 2 hours. The light emission control circuit 5 is not limited to outputting the light emission command signal as a rectangular wave, and may output the light emission command signal as a sine wave or a sawtooth wave.

位相型ＴＯＦ計測部６ｂは、発光期間において、受光指令信号を受光制御回路６から選択回路１０に出力させ、各受光素子群１１ａ〜１１ｎの第１〜第４の単位蓄積部１５ａ〜１５ｄにおける電荷を蓄積するタイミングを制御する。即ち、位相型ＴＯＦ計測部６ｂは、発光指令信号の周期Ｔｓを４等分した時間を、それぞれ順にＴ１、Ｔ２、Ｔ３、Ｔ４とすると、発光素子８の発光と同期するタイミングで第１の単位蓄積部１５ａをＴｓ／２時間オンする（蓄積Ｑ１）。又、位相型ＴＯＦ計測部６ｂは、第１の単位蓄積部１５ａのオンからＴ１遅れたタイミングで第２の単位蓄積部１５ｂをＴｓ／２時間オンする（蓄積Ｑ２）。又、位相型ＴＯＦ計測部６ｂは、第１の単位蓄積部１５ａのオンから（Ｔ１＋Ｔ２）遅れたタイミングで第３の単位蓄積部１５ｃをＴｓ／２時間オンする（蓄積Ｑ３）。更に、位相型ＴＯＦ計測部６ｂは、第１の単位蓄積部１５ａのオンから（Ｔ１＋Ｔ２＋Ｔ３）遅れたタイミングで第４の単位蓄積部１５ｄをＴｓ／２時間オンする（蓄積Ｑ４）。位相型ＴＯＦ計測部６ｂは、このように周期Ｔｓを４等分した時間ずつずらして電荷を振り分け、変調光の発光からそれぞれ０度、９０度、１８０度、２７０度位相がずれた電荷の蓄積を繰り返させる。 The phase-type TOF measurement unit 6b outputs a light reception command signal from the light reception control circuit 6 to the selection circuit 10 during the light emission period, and charges in the first to fourth unit accumulation units 15a to 15d of the light receiving element groups 11a to 11n. Control the timing to store the. That is, the phase-type TOF measurement unit 6b, the divided into four equal parts the time period Ts of the light emission command signal, respectively signals T 1, T 2, T 3 , T 4 in order, at a timing synchronized with light emission of the light emitting element 8 The first unit accumulation unit 15a is turned on for Ts / 2 hours (accumulation Q1). The phase-type TOF measurement unit 6b, a second unit storage section 15b turns on Ts / 2 hours by T 1 delayed timing from ON of the first unit storage portion 15a (accumulation Q2). The phase-type TOF measurement unit 6b turns on the third unit storage unit 15c for Ts / 2 hours (storage Q3) at a timing delayed by (T 1 + T 2 ) after the first unit storage unit 15a is turned on. Further, the phase-type TOF measuring unit 6b turns on the fourth unit storage unit 15d for Ts / 2 hours at a timing delayed by (T 1 + T 2 + T 3 ) from the turn-on of the first unit storage unit 15a (storage Q4). . In this way, the phase-type TOF measuring unit 6b distributes the charges by shifting the period Ts by four equal intervals, and accumulates charges whose phases are shifted by 0 degrees, 90 degrees, 180 degrees, and 270 degrees from the emission of the modulated light, respectively. Repeat.

一般的に、自装置から対象物までの距離を計測するには、数ｍｓ程度の時間の電荷の蓄積が必要である。一方、発光素子８から発光される変調光の発光周波数（変調周波数）は数十ＭＨｚである。よって、変調の１周期Ｔｓは数十ｎｓ程度である。このため、自装置から対象物までの距離を計測するには、数千〜数十万周期の露光期間（電荷蓄積期間）を必要とする。位相型ＴＯＦ計測部６ｂは、露光期間の時間間隔毎に第１〜第４の単位蓄積部１５ａ〜１５ｄに蓄積されている電荷の電荷量を読み出す。   Generally, in order to measure the distance from its own device to an object, it is necessary to accumulate charges for a time of about several ms. On the other hand, the emission frequency (modulation frequency) of the modulated light emitted from the light emitting element 8 is several tens of MHz. Therefore, one modulation period Ts is about several tens of ns. For this reason, in order to measure the distance from the own apparatus to the object, an exposure period (charge accumulation period) of several thousand to several hundred thousand cycles is required. The phase-type TOF measuring unit 6b reads the charge amount accumulated in the first to fourth unit accumulating units 15a to 15d at each time interval of the exposure period.

位相型ＴＯＦ計測部６ｂは、第１〜第４の単位蓄積部１５ａ〜１５ｄに蓄積されている電荷の電荷量を読み出すと、以下のようにして自装置から対象物までの距離を計測する。発光素子８から発光された変調光と、変調光が対象物で反射して各受光素子群１１ａ〜１１ｎに受光される戻り光との間には、光が対象物まで往復する飛行時間による位相差（遅延時間）が生じる。位相型ＴＯＦ計測部６ｂは、第１〜第４の単位蓄積部１５ａ〜１５ｄに蓄積されている電荷の電荷量をそれぞれＣ１、Ｃ２、Ｃ３、Ｃ４とすると、次式（１）により位相差φを計測する。   When the phase-type TOF measurement unit 6b reads the charge amount of the charges accumulated in the first to fourth unit accumulation units 15a to 15d, it measures the distance from the own device to the target as follows. Between the modulated light emitted from the light emitting element 8 and the return light reflected by the object and received by each of the light receiving element groups 11a to 11n, the time depending on the flight time when the light reciprocates to the object. A phase difference (delay time) occurs. The phase-type TOF measurement unit 6b has a phase difference φ according to the following equation (1) when the charge amounts of the charges accumulated in the first to fourth unit accumulation units 15a to 15d are C1, C2, C3, and C4, respectively. Measure.

φ＝ｔａｎ−１［（Ｃ１−Ｃ３）／（Ｃ２−Ｃ４）］…（１）
尚、各受光素子群１１ａ〜１１ｎには戻り光の他に背景光も入射光として受光されるが、入射光のうち戻り光による（戻り光成分の）電荷は遅延時間に応じて第１〜第４の単位蓄積部１５ａ〜１５ｄに割り振られる。そのため、第１〜第４の単位蓄積部１５ａ〜１５ｄに蓄積される戻り光による電荷の電荷量は異なる。一方、入射光のうち背景光による（背景光成分の）電荷は均等に第１〜第４の単位蓄積部１５ａ〜１５ｄに割り振られる。そのため、第１〜第４の単位蓄積部１５ａ〜１５ｄに蓄積される背景光による電荷の電荷量は略等しくなる。上記した式（１）では、背景光による電荷の電荷量が相殺されるので、背景光の影響を受けずに位相差φを計測することができる。 φ = tan −1 [(C1-C3) / (C2-C4)] (1)
Note that each of the light receiving element groups 11a to 11n receives background light as incident light in addition to the return light, but the charge of the return light (return light component) of the incident light depends on the delay time. The fourth unit accumulating units 15a to 15d are allocated. Therefore, the charge amount of the return light accumulated in the first to fourth unit accumulation units 15a to 15d is different. On the other hand, the electric charge by the background light (background light component) in the incident light is equally allocated to the first to fourth unit accumulating units 15a to 15d. Therefore, the charge amount of the background light accumulated in the first to fourth unit accumulating units 15a to 15d is substantially equal. In the above equation (1), since the charge amount of the background light is canceled, the phase difference φ can be measured without being affected by the background light.

距離取得部６ｃは、変調光と戻り光との間の位相差φが位相型ＴＯＦ計測部６ｂにより計測されると、その計測された位相差φ、周期Ｔｓ、光速ｃを用い、次式（２）により自装置から対象物までの距離Ｄを計算して取得する。   When the phase difference φ between the modulated light and the return light is measured by the phase-type TOF measurement unit 6b, the distance acquisition unit 6c uses the measured phase difference φ, the period Ts, and the speed of light c to obtain the following formula ( The distance D from the own device to the object is calculated and acquired by 2).

Ｄ＝（φ／２π）・（ｃ／２Ｔｓ）…（２）
尚、位相型ＴＯＦ計測部６ｂは、第１〜第４の単位蓄積部１５ａ〜１５ｄに蓄積されている電荷の電荷量を読み出す場合に、それらの電荷量を同時に読み出しても良いし個別に読み出しても良いし、複数のフレームに亘って読み出しても良い。又、本実施形態では、電荷蓄積部１４を４個の単位蓄積部１５ａ〜１５ｄで構成する場合を例示したが、互いに異なる位相の電荷量に基づいて自装置から対象物までの距離Ｄを計算して取得可能であれば、単位蓄積部の個数は２以上の幾つであっても良い。 D = (φ / 2π) · (c / 2Ts) (2)
The phase-type TOF measurement unit 6b may read out the charge amounts stored in the first to fourth unit storage units 15a to 15d at the same time or individually. Alternatively, it may be read over a plurality of frames. Further, in the present embodiment, the case where the charge storage unit 14 is configured by the four unit storage units 15a to 15d is exemplified, but the distance D from the own device to the object is calculated based on the charge amounts of different phases. As long as it can be acquired, the number of unit storage units may be any number of two or more.

図９は、制御部２が行う処理の流れを示している。制御部２は、自装置から対象物までの測距の開始条件が成立すると測距を開始する。制御部２は、測距を開始すると、受光スロット特定を受光スロット特定部６ａにより行い、戻り光が受光された距離スロットを受光スロットとして特定する（Ｓ１）。このとき、制御部２は、発光波形のデューティーを６．２５％とし、発光ピークパワーを従来の８倍として変調光を発光素子８から発光させる。   FIG. 9 shows the flow of processing performed by the control unit 2. The control unit 2 starts distance measurement when a distance measurement start condition from the own device to the object is satisfied. When the distance measurement is started, the control unit 2 specifies the light receiving slot by the light receiving slot specifying unit 6a, and specifies the distance slot in which the return light is received as the light receiving slot (S1). At this time, the control unit 2 causes the light emitting element 8 to emit modulated light by setting the duty of the light emission waveform to 6.25% and the light emission peak power to be eight times that of the prior art.

次いで、制御部２は、受光スロットを特定すると、位相型ＴＯＦ計測を位相型ＴＯＦ計測部６ｂにより行い、その特定した受光スロットの１周期内での位相差を計測する（Ｓ２）。このとき、制御部２は、発光波形を低デューティー化しても良いししなくても良い。制御部２は、発光波形を低デューティー化する場合であれば、図１０に示すように、発光波形のデューティーを６．２５％とし、発光ピークパワーを従来の（発光波形のデューティーを５０％とするときの）８倍として変調光を発光素子８から発光させ、受光スロットのみに対して位相差の計測を行う。この場合には、最大強度の戻り光が存在すると特定した距離スロットのみに対して位相差の計測を行うことにより、マルチパスやミックスドピクセルの原因となり得る複数の戻り光を同時に計測してしまうことがなくなり、マルチパスやミックスドピクセルの発生を未然に防ぐことができる。又、制御部２は、発光波形を低デューティー化しない場合であれば、図１１に示すように、発光波形のデューティーを従来の５０％のままとし、全ての距離スロットに対して位相差の計測を行う。この場合には、従来の制御をそのまま流用して実現することができる。そして、制御部２は、位相差を計測すると、その計測した位相差を用い、自装置から対象物までの詳細な距離を計算して取得する（Ｓ３）。   Next, when the light receiving slot is specified, the control unit 2 performs phase-type TOF measurement with the phase-type TOF measuring unit 6b, and measures the phase difference within one cycle of the specified light receiving slot (S2). At this time, the control unit 2 may or may not reduce the duty of the light emission waveform. In the case where the duty of the light emission waveform is reduced, the control unit 2 sets the light emission waveform duty to 6.25% and the light emission peak power to the conventional (light emission waveform duty to 50% as shown in FIG. The modulated light is emitted from the light emitting element 8 as 8 times, and the phase difference is measured only for the light receiving slot. In this case, by measuring the phase difference only for the distance slot that is identified as having the maximum intensity of return light, a plurality of return lights that may cause multi-pass and mixed pixels are simultaneously measured. This eliminates the occurrence of multi-pass and mixed pixels. In addition, if the duty of the light emission waveform is not reduced, the control unit 2 keeps the duty of the light emission waveform at 50% of the conventional value and measures the phase difference for all the distance slots as shown in FIG. I do. In this case, the conventional control can be used as it is. And the control part 2 will calculate and acquire the detailed distance from an own apparatus to a target object using the measured phase difference, if a phase difference is measured (S3).

このように本発明は、図１２に示すように、受光スロット特定と位相型ＴＯＦ計測とを組み合わせ、受光スロット特定により自装置から対象物までの大まかな距離を遠距離まで計測し、位相型ＴＯＦ計測により受光スロットの１周期内での位相差を計測することで、自装置から対象物までの詳細な距離を計算して取得する。   In this way, as shown in FIG. 12, the present invention combines light receiving slot identification and phase-type TOF measurement, and measures the approximate distance from its own device to the object by far light identification by specifying the light-receiving slot. By measuring the phase difference within one cycle of the light receiving slot by measurement, the detailed distance from the device to the object is calculated and acquired.

尚、以上に説明した一連の処理では、１つの距離スロットの時間間隔を、図１３に示すように、変調光と戻り光との間の位相差を計測するときの１周期（２π）としたが、図１４に示すように、半周期（π）としても良い。又、このように受光スロット特定と位相型ＴＯＦ計測とを組み合わせる構成では、車載アプリやシステム要件に依存する距離精度の要求により露光パターンや発光ピークパワーを最適に調整すれば良い。近距離のみで高い精度が要求される場合であれば、図１５に示すように、受光スロット特定を目標最長距離までとし、位相型ＴＯＦ計測を近距離までとする調整を行うことで、近距離で高い精度の測距を実現することができつつ、処理時間を低減することができ、又、必要な発光強度を抑えることができる。又、全域で高い精度が要求される場合であれば、図１６に示すように、受光スロット特定と位相型ＴＯＦ計測との両方を目標最長距離までとする調整を行うことで、全域で高い精度の測距を実現することができる。   In the series of processes described above, the time interval of one distance slot is set to one cycle (2π) when measuring the phase difference between the modulated light and the return light, as shown in FIG. However, as shown in FIG. 14, it is good also as a half period ((pi)). Further, in the configuration in which the light receiving slot identification and the phase-type TOF measurement are combined as described above, the exposure pattern and the light emission peak power may be optimally adjusted according to the requirement of distance accuracy depending on the in-vehicle application and system requirements. If high accuracy is required only at a short distance, as shown in FIG. 15, by adjusting the light receiving slot to the target longest distance and adjusting the phase-type TOF measurement to a short distance, Thus, it is possible to reduce the processing time while suppressing the required light emission intensity while realizing highly accurate ranging. If high accuracy is required in the entire area, as shown in FIG. 16, high accuracy can be achieved in the entire area by adjusting both the light receiving slot specification and the phase-type TOF measurement to the target maximum distance. Can be achieved.

以上に説明したように第１の実施形態によれば、次に示す作用効果を得ることができる。光飛行型測距装置１において、変調光が発光されたことで戻り光が受光された受光スロットを受光スロット特定部６ａにより特定し、変調光と戻り光との間の位相差を位相型ＴＯＦ計測部６ｂにより計測する。そして、受光スロット特定部６ａによる特定結果と位相型ＴＯＦ計測部６ｂによる計測結果とを組み合わせることで、それぞれの方法による利点を両立するようにした。即ち、受光スロット特定により自装置から対象物までの大まかな距離を遠距離まで計測し、位相型ＴＯＦ計測により受光スロットの１周期内での位相差を計測することで、自装置から対象物までの詳細な距離を計算して取得する。これにより、発光強度を高めることを不要として装置全体の大型化を回避しつつ、遠距離測距でも必要な距離精度を維持することができる。   As described above, according to the first embodiment, the following operational effects can be obtained. In the optical flight type distance measuring device 1, the light receiving slot specifying unit 6a specifies the light receiving slot in which the return light is received by the modulated light being emitted, and the phase difference between the modulated light and the return light is determined by the phase TOF. Measurement is performed by the measurement unit 6b. Then, by combining the result of identification by the light receiving slot identification unit 6a and the result of measurement by the phase-type TOF measurement unit 6b, the advantages of the respective methods are compatible. That is, a rough distance from the own device to the object is measured by specifying the light receiving slot to a long distance, and a phase difference within one cycle of the light receiving slot is measured by the phase-type TOF measurement. Calculate and get the detailed distance. Thereby, it is possible to maintain the required distance accuracy even in long-distance ranging while avoiding the increase in the size of the entire apparatus without increasing the emission intensity.

（第２の実施形態）
次に、本発明の第２の実施形態について、図１７を参照して説明する。尚、上記した第１の実施形態と同一部分については説明を省略し、異なる部分について説明する。第１の実施形態は、受光部４において、縦方向のラインを構成する受光素子群１１毎にサンプリング動作を制御する構成であるが、第２の実施形態は、受光素子１２毎にサンプリング動作を制御する構成である。即ち、光飛行型測距装置２１において、受光部２２４は、選択回路１０と、マトリックス状に配列されている複数の受光素子２３とを有する。各受光素子２３は、選択回路１０から受光指令を入力すると、発光素子８から発光された変調光が対象物で反射した戻り光を含む入射光の受光を待機する。又、各受光素子２３は、選択回路１０から読出指令を入力すると、蓄積されている電荷の電荷量（受光量）を受光制御回路６に出力する。第２の実施形態によれば、必要な距離精度を画素単位で実現することができる。 (Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. In addition, description is abbreviate | omitted about the same part as above-mentioned 1st Embodiment, and a different part is demonstrated. The first embodiment is configured to control the sampling operation for each light receiving element group 11 constituting the vertical line in the light receiving unit 4, but in the second embodiment, the sampling operation is performed for each light receiving element 12. It is the structure to control. That is, in the optical flight rangefinder 21, the light receiving unit 224 includes the selection circuit 10 and a plurality of light receiving elements 23 arranged in a matrix. When each light receiving element 23 receives a light reception command from the selection circuit 10, the light receiving element 23 waits for reception of incident light including return light reflected by the object from the modulated light emitted from the light emitting element 8. Each light receiving element 23 outputs a stored charge amount (light receiving amount) to the light receiving control circuit 6 when a read command is input from the selection circuit 10. According to the second embodiment, the required distance accuracy can be realized in units of pixels.

（その他の実施形態）
本発明は、上記した実施形態にのみ限定されるものではなく、以下のように変形又は拡張することができる。
車両以外の用途に適用しても良い。
変調光の発光波形を低デューティー化することとして、発光波形のデューティーを５０％よりも短くすれば、発光波形のデューティーを６．２５％以外の値に短くしても良い。又、発光波形のデューティーを５０％よりも短くした場合に、発光波形のデューティーを５０％としたときとエネルギー的に等価となる範囲内で、発光ピークパワーを高めれば良い。即ち、発光波形のデューティーを例えば１２．５％とするときには、発光ピークパワーを従来の４倍として変調光を発光させれば良い。 (Other embodiments)
The present invention is not limited to the above-described embodiment, and can be modified or expanded as follows.
You may apply to uses other than a vehicle.
In order to reduce the duty of the light emission waveform of the modulated light, if the duty of the light emission waveform is made shorter than 50%, the duty of the light emission waveform may be shortened to a value other than 6.25%. Further, when the duty of the light emission waveform is shorter than 50%, the light emission peak power may be increased within a range that is energetically equivalent to that when the duty of the light emission waveform is 50%. That is, when the duty of the light emission waveform is set to 12.5%, for example, the modulated light may be emitted by setting the light emission peak power to four times that of the prior art.

本実施形態では、先に受光スロット特定を行い、後から位相型ＴＯＦ計測を行う構成を例示したが、先に位相型ＴＯＦ計測を行い、後から受光スロット特定を行う構成でも良い。即ち、位相型ＴＯＦ計測では発光波形のデューティーを５０％として全ての距離スロットに対して位相差の計測を行い、受光スロット特定では発光波形のデューティーを５０％よりも短くして受光スロットを特定すれば良い。   In the present embodiment, the configuration in which the light receiving slot is identified first and the phase-type TOF measurement is performed later is illustrated, but the configuration in which the phase-type TOF measurement is performed first and the light receiving slot is identified later may be employed. That is, in the phase-type TOF measurement, the duty of the light emission waveform is set to 50%, and the phase difference is measured for all the distance slots, and in the light receiving slot specification, the light receiving waveform duty is made shorter than 50% to specify the light receiving slot. It ’s fine.

図面中、１、２１は光飛行型測距装置、３は発光部（発光手段）、４、２２は受光部（受光手段）、５は発光制御回路（発光制御手段）、６は受光制御回路（受光制御手段）、６ａは受光スロット特定部（受光スロット特定手段）、６ｂは位相型ＴＯＦ計測部（位相型ＴＯＦ計測手段）、６ｃは距離取得部（距離取得手段）である。   In the drawings, 1 and 21 are optical flight distance measuring devices, 3 is a light emitting part (light emitting means), 4 and 22 are light receiving parts (light receiving means), 5 is a light emission control circuit (light emission control means), and 6 is a light reception control circuit. (Light receiving control means), 6a is a light receiving slot specifying section (light receiving slot specifying means), 6b is a phase type TOF measuring section (phase type TOF measuring means), and 6c is a distance acquiring section (distance acquiring means).

Claims (7)

変調光を空間に発光する発光手段（８）と、
前記発光手段から発光された変調光が対象物で反射した戻り光を含む入射光を受光して電荷を蓄積する受光手段（４、２２）と、
前記発光手段の発光動作を制御する発光制御手段（５）と、
前記受光手段の受光動作を制御する受光制御手段（６）と、
前記発光手段から変調光が発光された時点を基点とする所定時間間隔の距離スロットのうち戻り光が前記受光手段に受光された距離スロットを受光スロットとして特定する受光スロット特定手段（６ａ）と、
前記受光手段における電荷の蓄積状態に基づいて変調光と戻り光との間の位相差を計測する位相型ＴＯＦ計測手段（６ｂ）と、
前記受光スロット特定手段による特定結果と前記位相型ＴＯＦ計測手段による計測結果とを組み合わせることで、自装置から対象物までの距離を計算して取得する距離取得手段（６ｃ）と、を備えたことを特徴とする光飛行型測距装置（１、２１）。 A light emitting means (8) for emitting modulated light in space;
A light receiving means (4, 22) for receiving incident light including return light reflected by an object from the modulated light emitted from the light emitting means and accumulating charges;
A light emission control means (5) for controlling the light emission operation of the light emission means;
A light receiving control means (6) for controlling the light receiving operation of the light receiving means;
A light receiving slot specifying means (6a) for specifying, as a light receiving slot, a distance slot in which return light is received by the light receiving means among distance slots of a predetermined time interval starting from the time when modulated light is emitted from the light emitting means;
Phase-type TOF measuring means (6b) for measuring the phase difference between the modulated light and the return light based on the charge accumulation state in the light receiving means;
Distance acquisition means (6c) for calculating and acquiring the distance from the device itself to the object by combining the result of identification by the light receiving slot identification means and the result of measurement by the phase-type TOF measurement means An optical flight-type distance measuring device (1, 21). 請求項１に記載した光飛行型測距装置において、
前記受光スロット特定手段は、バイナリコードのサンプリングパターンを用いて前記受光スロットを特定することを特徴とする光飛行型測距装置。 In the optical flight type distance measuring device according to claim 1,
The optical flight rangefinder characterized in that the light receiving slot specifying means specifies the light receiving slot using a binary code sampling pattern. 請求項１に記載した光飛行型測距装置において、
前記受光スロット特定手段は、グレイコードのサンプリングパターンを用いて前記受光スロットを特定することを特徴とする光飛行型測距装置。 In the optical flight type distance measuring device according to claim 1,
The optical flight type distance measuring device, wherein the light receiving slot specifying means specifies the light receiving slot using a gray code sampling pattern. 請求項１から３の何れか一項に記載した光飛行型測距装置において、
前記発光制御手段は、発光波形のデューティーを５０％よりも短くし、その分、発光ピークパワーを高めて変調光を前記発光手段から発光させ、
前記受光スロット特定手段は、前記発光手段から当該発光ピークパワーが高められた変調光が発光されたことで、前記受光スロットを特定することを特徴とする光飛行型測距装置。 In the optical flight type distance measuring device according to any one of claims 1 to 3,
The light emission control means shortens the duty of the light emission waveform to less than 50%, increases the emission peak power correspondingly, and emits modulated light from the light emission means,
The optical flight range finder according to claim 1, wherein the light receiving slot specifying means specifies the light receiving slot when the light emitting means emits modulated light having an increased emission peak power. 請求項１から４の何れか一項に記載した光飛行型測距装置において、
前記発光制御手段は、発光波形のデューティーを５０％よりも短くし、その分、デューティーを５０％とするときよりも発光ピークパワーを高めて変調光を前記発光手段から発光させ、
前記位相型ＴＯＦ計測手段は、前記受光スロットのみに対して位相差の計測を行うことを特徴とする光飛型測距装置。 In the optical flight type distance measuring device according to any one of claims 1 to 4,
The light emission control means shortens the duty of the light emission waveform to less than 50%, and accordingly, emits modulated light from the light emission means by increasing the light emission peak power than when the duty is 50%,
The phase-type TOF measuring means measures a phase difference only with respect to the light receiving slot. 請求項１から４の何れか一項に記載した光飛行型測距装置において、
前記発光制御手段は、発光波形のデューティーを５０％として変調光を前記発光手段から発光させ、
前記位相型ＴＯＦ計測手段は、前記受光スロットを含む全ての距離スロットに対して位相差の計測を行うことを特徴とする光飛行型測距装置。 In the optical flight type distance measuring device according to any one of claims 1 to 4,
The light emission control means causes the modulated light to be emitted from the light emission means with a duty of a light emission waveform as 50%,
The optical flight type distance measuring device, wherein the phase-type TOF measuring means measures phase differences for all distance slots including the light receiving slot. 請求項１から６の何れか一項に記載した光飛行型測距装置において、
前記受光スロット特定手段は、一の距離スロットの時間間隔を、前記位相型ＴＯＦ計測手段が変調光と戻り光との間の位相差を計測するときの１周期とすることを特徴とする光飛行型測距装置。 In the optical flight type distance measuring device according to any one of claims 1 to 6,
The light receiving slot specifying means sets the time interval of one distance slot as one period when the phase-type TOF measuring means measures the phase difference between the modulated light and the return light. Type ranging device.
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