JP2011053137A - Optical range finder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical range finder that changes operation condition as required. <P>SOLUTION: The optical range finder 1 includes: an optical scanning unit 5 that can apply Lissajous scanning to light entering an optical reflection surface in an objective region by rocking of a movable unit having the optical reflection surface; a drive unit 7 that supplies first and second driving signals for rocking the movable unit in first and second directions, respectively, to the optical scanning unit 5 to rock and drive the movable unit; a light source unit 9 to emit pulse light toward the optical reflection surface; a light receiving unit 11 to receive the reflection light of the pulse light; and a distance measurement unit 13 to measure a distance to an object reflecting the pulse light based on the outgoing timing of the pulse light and the light receiving timing of the reflection light. The drive unit 7 includes at least either of a phase difference changing unit 72 for changing a phase difference between the first and second driving signals and an amplitude changing unit 73 for changing the rocking amplitude of the movable unit while adjusting the size of the first and second driving signals. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical distance measuring device for measuring the distance of an object existing in a target region by Lissajous scanning laser light (pulse light) in the target region.

  2. Description of the Related Art Conventionally, there has been known an optical distance measuring device that measures the distance to an object by performing Lissajous scanning with laser light within the object region. This type of optical distance measuring device receives, for example, a light source that emits a laser pulse, a scanning mechanism that includes a two-dimensional resonant galvanometer mirror, a scanning drive unit that drives the scanning mechanism, and a reflected laser pulse. A light receiving unit, and a distance measuring unit that measures a distance to the object based on a time difference between the emission timing of the laser pulse and the light reception timing of the reflected light.

JP 2004-157796 A

  By the way, in the optical distance measuring apparatus adopting the distance measuring method by the Lissajous scanning as in the above prior art, the angle resolution is improved, that is, the position for measuring the distance in the target region (hereinafter simply referred to as “measurement position”). An increase is required. For example, the measurement position in the target area can be increased by narrowing the interval of the Lissajous scanning trajectory in the target area.

  However, there is a limit to the time interval during which laser pulses can be emitted continuously in terms of the performance and safety of the light source. If the number of measurement positions is increased, the number of Lissajous scans necessary for ranging at all measurement positions ( Or the scanning period) also increases. In the above scanning mechanism, it is difficult to significantly reduce the Lissajous scanning cycle. For this reason, normally, when the measurement position is increased, the time until the distance measurement for the target region is completed (hereinafter referred to as “distance measurement completion time”) becomes longer.

  On the other hand, in consideration of an object that moves or passes through the target area in a short time, the distance measurement completion time is preferably as short as possible. However, in this case, the measurement position in the target area cannot be increased.

  In this way, in the distance measurement method using Lissajous scanning, there is a trade-off between improving the angular resolution (increasing the measurement position) and shortening the distance measurement completion time, and optical distance measurement to satisfy one of the requirements. When the device is configured, it is difficult for the optical distance measuring device to respond to the change in request when the request changes to the other.

  The present invention has been made paying attention to such a problem, and in an optical distance measuring device adopting a distance measuring method by Lissajous scanning, an optical distance measuring device whose operation state can be changed as required. The purpose is to provide.

  In the optical distance measuring device according to the present invention, a movable part having a light reflecting surface is formed so as to be able to swing in a first direction and a second direction orthogonal to each other, and the movable part is swung to be incident on the light reflecting surface. An optical scanning unit capable of Lissajous scanning within the target area, a first drive signal for swinging the movable unit in the first direction, and a second drive signal for swinging the movable unit in the second direction. A drive unit that swings and drives the movable unit by supplying to the optical scanning unit, a light source unit that emits pulsed light toward the light reflecting surface, and pulsed light emitted from the light source unit within the target region A light receiving unit that receives the reflected light reflected by the object existing in the light source, and a distance measuring unit that measures the distance of the object based on the emission timing of the pulsed light by the light source unit and the light reception timing of the reflected light by the light receiving unit And the drive unit A phase difference changing unit that changes a phase difference between the first drive signal and the second drive signal; and swinging the movable unit by adjusting the magnitudes of the first drive signal and the second drive signal. It includes at least one of amplitude changing sections that change the amplitude.

  According to the optical distance measuring device of the present invention, the drive unit that swings and drives the movable part (light reflection surface) of the optical scanning unit includes at least one of the phase difference changing unit and the amplitude changing unit, for example, the optical scanning unit Increase the measurement position in the target area by narrowing the interval of the Lissajous scanning trajectory by, or target every 1/2 cycle of the Lissajous scanning as almost the same scanning trajectory in the first and second half of the Lissajous scanning cycle by the optical scanning unit It becomes possible to complete the distance measurement for the region. Thereby, the operation state of the optical distance measuring device can be changed according to a request, and the distance can be measured in a preferable state.

It is a block diagram which shows schematic structure of the optical ranging apparatus by 1st Embodiment. It is a figure which shows the structure of a two-dimensional galvanometer mirror as an optical scanning part of an optical distance measuring device. It is a figure which shows the Lissajous scanning locus | trajectory by the optical scanning part when changing the phase difference of a 1st drive signal and a 2nd drive signal. It is a figure which shows the same Lissajous scanning locus | trajectory in which the scanning direction is mutually reverse by the first half and the second half of a Lissajous scanning period. It is a figure which shows a Lissajous scanning locus when the oscillation amplitude of an inner side movable part is made small. It is a figure which shows the principal part of the 1st modification of the optical ranging apparatus by 1st Embodiment. It is a figure which shows the principal part of the 2nd modification of the optical ranging apparatus by 1st Embodiment. It is a block diagram which shows schematic structure of the optical ranging apparatus by 2nd Embodiment. It is a figure which shows the example of the Lissajous scanning locus | trajectory by the optical scanning part in 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of the optical distance measuring device according to the first embodiment of the present invention.
The optical distance measuring device 1 according to the present embodiment performs a Lissajous scan with pulsed light (laser pulse) in a target region, measures a distance to an object existing in the target region (ranging), and based on the measurement result. A distance image is generated and output (displayed).

  The optical distance measuring device 1 according to the present embodiment is configured to be operable in a plurality of operation modes. As shown in FIG. 1, an information input unit 3, an electromagnetically driven optical scanning unit 5, and an optical scanning unit. 5, a light source unit 9 that emits pulsed light, a light receiving unit 11 that receives reflected light of the emitted pulsed light, and a distance measuring unit that measures the distance to an object that reflects the pulsed light 13, an image generation unit 15 that generates a distance image based on a measurement result by the distance measurement unit 13, and a display unit 17 that outputs (displays) the generated distance image.

  For example, the user inputs information related to the operation of the optical distance measuring device 1, for example, a mode selection command for selecting an operation mode of the optical distance measuring device 1 to the information input unit 3. The operation modes that can be selected in the present embodiment include a basic “normal measurement mode”, a “detailed measurement mode” that performs detailed ranging for the target area by increasing the number of measurement positions compared to the normal measurement mode, A “partial detail mode” for performing detailed distance measurement for a part and a “high-speed measurement mode” for which the distance measurement completion time for the target region is shorter than that in the normal measurement mode are included.

  The optical scanning unit 5 is formed such that a movable unit having a light reflection surface (mirror) can swing in a first direction and a second direction orthogonal to each other, and emits light (pulse light) incident on the light reflection surface. Two-dimensional scanning, more specifically, Lissajous scanning can be performed within the target region. As such an optical scanning unit 5, for example, a two-dimensional scanning semiconductor galvanometer mirror (hereinafter simply referred to as “two-dimensional galvanometer mirror”) described in Japanese Patent No. 2722314 proposed by the present applicant is used. it can.

FIG. 2 shows a configuration of a two-dimensional galvanometer mirror 50 as a specific example of the optical scanning unit 5.
As shown in FIG. 2, the two-dimensional galvanometer mirror 50 is an outer movable member that is disposed inside the fixed portion 51 and is supported by a pair of first torsion bars 52, 52 so as to be swingable. A portion 53 and an inner movable portion 55 that is disposed inside the outer movable portion 53 and is swingably supported by a pair of second torsion bars 54, 54 that are orthogonal to the first torsion bars 52, 52. Is provided.

  A light reflecting surface (mirror) 56 is formed at the central portion of the inner movable portion 55, and a first drive coil 57 and a second drive coil 58 are formed at the peripheral portions of the outer movable portion 53 and the inner movable portion 55, respectively. Yes. The end of the first drive coil 57 is connected to first electrode terminals 59 and 59 formed on the fixed portion 51, and the end of the second drive coil 58 is connected to the second electrode terminal 60 formed on the fixed portion 51. , 60.

  In addition, a pair of first permanent magnets 61 and 61 for applying a magnetic field to the first drive coil 57 and a pair of second permanent magnets 62 and 62 for applying a magnetic field to the second drive coil 58 are opposed to each other with the fixing portion 51 interposed therebetween. Has been placed. The fixed portion 51, the first torsion bars 52, 52, the outer movable portion 53, the second torsion bars 54, 54, and the inner movable portion 55 are integrally formed from a semiconductor substrate.

  The two-dimensional galvanometer mirror 50 has an outer movable portion by a current (alternating current) flowing through the first drive coil 57 and the second drive coil 58 and a magnetic field generated by the first permanent magnets 61 and 61 and the second permanent magnets 62 and 62. A Lorentz force acts on 53 and the inner movable part 55, and as a result, the inner movable part 55 swings in a two-dimensional direction. As the inner movable portion 55 swings, the pulsed light incident on the light reflecting surface 56 is Lissajous scanned within the target region.

  The drive unit 7 supplies a drive signal (vibration current) to the optical scanning unit 5 through the first electrode terminals 59 and 59 and the second electrode terminals 60 and 60 to cause the inner movable unit 55 (and the outer movable unit 53) to move. Swing drive. The drive unit 7 supplies a first drive signal to the first drive coil 57 and supplies a second drive signal to the second drive coil 58, and a phase difference between the first drive signal and the second drive signal. A phase difference changing unit 72 that changes the amplitude, and an amplitude changing unit 73 that changes the swing amplitude of the inner movable unit 55 by adjusting the magnitude (amplitude) of the first drive signal and the second drive signal.

  The drive circuit 71 inputs the phase difference from the phase difference changing unit 72 and the magnitudes of the first and second drive signals from the amplitude changing unit 73, and the first drive signal and the second drive signal having the inputted magnitudes. Are supplied to the optical scanning unit 5 with the inputted phase difference. Here, the frequency of the first drive signal and the frequency of the second drive signal are set to frequencies that are the same as or close to the resonance frequency of the two-dimensional galvanometer mirror 50, and the first drive signal is set to the first drive coil 57. The outer movable portion 53 and the inner movable portion 55 swing around the axes of the first torsion bars 52, 52 by supplying the second drive signal to the second drive coil 58. It swings around the axis of the second torsion bars 54, 54. In the present embodiment, the pulsed light incident on the light reflecting surface 56 is scanned in the horizontal direction by the swinging of the outer movable portion 53 and the inner movable portion 55 due to the supply of the first drive signal, and the second drive signal It is assumed that the pulsed light incident on the light reflecting surface 56 is scanned in the vertical direction by the swinging of the inner movable portion 55 by the supply.

  The phase difference changing unit 72 changes the phase difference between the first drive signal and the second drive signal with reference to the first drive signal (frequency). Specifically, the phase difference changing unit 72 sets the phase difference between the first drive signal and the second drive signal in accordance with the mode selection command input via the information input unit 3, and sets the set phase difference. Output to the drive circuit 71.

  FIG. 3 shows a Lissajous scanning locus by the optical scanning unit 5 when the phase difference between the first driving signal and the second driving signal is changed. Here, the phase difference between the first drive signal and the second drive signal, that is, the phase difference between the horizontal direction scan and the vertical direction scan is changed every π / 4 (rad) between 0 and 2π (rad). The Lissajous scanning trajectory in the case of being made is shown.

The Lissajous scanning trajectory returns to the scanning starting point again after a period (Lissajous period) determined from the frequency of the first driving signal (horizontal scanning period) and the frequency of the second driving signal (vertical scanning period). In the present embodiment, the frequency of the first drive signal is 1600.00 (Hz), and the frequency of the second drive signal is 444.44 (Hz).
As shown in FIG. 3, by changing the phase difference, the interval of the Lissajous scanning trajectory by the optical scanning unit 5 can be made dense or rough. In this embodiment, when the phase difference is π / 2 (3π / 2 is the same), the interval of the Lissajous scanning trajectory is the smallest. If the interval of the Lissajous scanning trajectory becomes close, it is possible to increase the measurement position in the target region (that is, improve the angular resolution). When the phase difference is 0 (same for π and 2π), as shown in FIG. 4, the first half (FIG. 4 (a)) and the second half (FIG. 4 (b)) of one cycle (TLs) of the Lissajous scanning. And the same Lissajous scanning trajectory with the scanning directions being opposite to each other. In this case, measurement (ranging) at the same position in the target area is possible in the first half and the second half of the Lissajous scanning cycle.

  The amplitude changing unit 73 adjusts the magnitude (amplitude) of the first drive signal and the second drive signal to change the swing amplitude of the inner movable unit 55 of the optical scanning unit 5. Specifically, the amplitude changing unit 73 sets the magnitudes of the first drive signal and the second drive signal in accordance with the mode selection command input via the information input unit 3, and drives the set magnitudes. Output to the circuit 71. If the swinging amplitude of the inner movable unit 55 is reduced, the Lissajous scanning range by the optical scanning unit 5 is reduced. If the swinging amplitude of the inner movable unit 55 is increased, the Lissajous scanning range by the optical scanning unit 5 is increased.

FIG. 5 shows an example of changing the swing amplitude of the inner movable portion 55 by the amplitude changing portion 73.
When the magnitudes of the first drive signal and the second drive signal are reduced at a constant rate to reduce the oscillation amplitude of the inner movable portion 55, the scanning range by the optical scanning portion 9, that is, the Lissajous as shown in FIG. Although the scanning trajectory becomes similar and small, the interval of the Lissajous scanning trajectory becomes close to a part of the target region. That is, it becomes a state in which a part of the target area is zoomed to perform distance measurement, and the measurement position can be increased for a part of the target area. However, since the scanning range (Lissajous scanning trajectory) by the optical scanning unit 9 becomes small, the direction of the optical distance measuring device 1 and the like so that the scanning range by the optical scanning unit 9 and the portion (area) to be measured coincide with each other. Need to be changed.

  Returning to FIG. 1, the light source unit 9 emits pulsed light toward the light reflecting surface 66 formed on the inner movable unit 55 of the optical scanning unit 5, and controls the light source 91 and the driving of the light source 91. A light source controller 92 and a light projecting optical system 93.

The light source 91 is a laser diode, for example, and emits pulsed light (laser pulse) by emitting light in response to a drive signal from the light source control unit 92.
The light source control unit 92 controls the light emission timing of the light source 91, that is, the emission timing of the pulsed light by the light source unit 9 in accordance with the mode selection command input via the information input unit 3. The light source control unit 92 includes a light emission timing table in which, for example, a measurement position in the target region and time (timing) are associated with each operation mode, and at a timing (measurement position) set in advance according to the operation mode. The light source 91 is caused to emit light.
The light projecting optical system 93 makes the pulsed light emitted from the light source 91 in a preferable state, and includes, for example, a collimator lens, and converts the pulsed light emitted from the light source 91 into parallel light.
Then, the pulsed light emitted from the light source unit 9 is reflected by the light reflecting surface 56 of the optical scanning unit 5 and is subjected to Lissajous scanning in the target region.

The light receiving unit 11 receives and detects pulsed light (reflected light) emitted from the light source unit 9 and reflected by an object existing in the target region, and for example, a photosensor can be used. The light receiving unit 11 may receive the reflected light directly, or may receive the reflected light via the optical scanning unit 5 (light reflecting surface 56).
The distance measuring unit 13 inputs the emission timing of the pulsed light from the light source unit 9 and the reception timing of the reflected light from the light receiving unit 11, and the object that reflects the pulsed light based on the time difference between them (light flight time). Measure the distance. The distance measurement by the distance measurement unit 13 is performed at each measurement position in the target area, that is, every time pulse light is emitted from the light source unit 9, and the measurement result is output to the image generation unit 15.

  The image generation unit 15 determines a pixel value at each measurement position based on the distance measured by the distance measurement unit 13, and generates a distance image for the target region. The generated distance image is, for example, an image having a different color for each measured distance, that is, a three-dimensional image in which the depth distance of an object existing in the target region is reflected. The distance image generated by the image generation unit 15 is output to the display unit 17. The display unit 17 includes a display and displays the distance image output from the image generation unit 15. It is possible to recognize not only the object existing in the target area from the distance image but also the change in the position of the object, the distance to the object, the posture of the object, and the like.

Next, the operation of the optical distance measuring device 1 having the above configuration will be described.
When the mode selection command for selecting the normal measurement mode is input from the information input unit 3 or when the mode selection command is not input from the information input unit 3, the optical distance measuring device 1 operates in the normal measurement mode. In this normal measurement mode, the phase difference between the first drive signal and the second drive signal by the phase difference changing unit 72, that is, the phase difference between the horizontal scanning and the vertical scanning by the optical scanning unit 5 is set to 0 (rad). The pulsed light is emitted from the light source unit 9 at a timing (measurement position) set in advance for the normal measurement mode. In this case, the optical distance measuring device 1 measures the distance at each measurement position (for example, the number of measurements = n1) on the Lissajous scanning locus shown in FIG. 3A, and measures at all the measurement positions in the target area. When the distance is completed (for example, every cycle of Lissajous scanning), a distance image for the target region is generated and output. That is, the distance image is updated every cycle of the Lissajous scan.

  When a mode selection command for selecting the detailed measurement mode is input from the information input unit 3, the optical distance measuring device 1 operates in the detailed measurement mode. In this detailed measurement mode, the phase difference between the first drive signal and the second drive signal is set (changed) to π / 2 (rad) by the phase difference changing unit 72 and set in advance for the detailed measurement mode from the light source unit 9. Pulsed light is emitted at the determined timing (measurement position). In this case, the optical distance measuring device 1 performs distance measurement at each measurement position (for example, measurement number = n2> n1) on the Lissajous scanning locus shown in FIG. 3C, and all the measurement positions in the target region. When the distance measurement is completed in (for example, every multiple cycles of Lissajous scanning), a distance image is generated and output. That is, the distance image is updated every multiple cycles of Lissajous scanning. In the detailed measurement mode, it is possible to perform more detailed measurement for the target area by increasing the number of measurement positions than in the normal measurement mode. However, since the pulse light is emitted at all measurement positions, the number of Lissajous scans increases and normal measurement is performed. The distance measurement completion time, that is, the distance image generation (update) cycle becomes longer than that in the mode (frame rate decreases). Therefore, the detailed measurement mode is usually selected when distance measurement more detailed than the frame rate is required.

  When a mode selection command for selecting the partial detailed mode is input from the information input unit 3, the optical distance measuring device 1 operates in the partial detailed mode. In this partial detailed mode, the phase difference change unit 72 sets the phase difference between the first drive signal and the second drive signal to 0 (rad), and the amplitude change unit 73 sets the magnitudes of the first drive signal and the second drive signal. Is set smaller at a constant rate than in the normal measurement mode, and pulsed light is emitted from the light source unit 9 at a preset timing for the partial measurement mode. However, here, it is assumed that pulsed light is emitted at the same timing as in the normal measurement mode. In this case, the optical distance measuring device 1 performs distance measurement at each measurement position (for example, the number of measurements = n1) on the scanning trajectory that is reduced as shown in FIG. 5, and the distance measurement is completed at all measurement positions. Then (for example, every period of Lissajous scanning), a distance image is generated and output. That is, the distance image is updated every cycle of the Lissajous scan. In the partial detailed mode, it is possible to perform detailed measurement on a part of the target area without reducing the frame rate as compared with the case of the normal measurement mode. Therefore, the partial detail mode is usually selected when the area where distance measurement is required is narrow.

  When a mode selection command for selecting the high-speed measurement mode is input from the information input unit 3, the optical distance measuring device 1 operates in the high-speed measurement mode. In this high-speed measurement mode, the phase difference between the first drive signal and the second drive signal is set to 0 (rad) by the phase difference changing unit 72, and the timing (measurement) set in advance for the high-speed measurement mode from the light source unit 9. Pulse light is emitted at the position). In the high-speed measurement mode, distance measurement is performed at the same position in the target area in the first half and the second half of one cycle of the Lissajous scan. In this case, the optical distance measuring device 1 performs distance measurement at each measurement position (for example, measurement number = n3 = n1 / 2) in the first half portion of the Lissajous scanning locus shown in FIG. When distance measurement is completed in (i.e., every half cycle of Lissajous scanning), a distance image is generated and output, and each measurement position (number of measurements) in the latter half of the Lissajous scanning locus shown in FIG. = N3), and distance measurement is completed at all measurement positions (that is, every 1/2 cycle of Lissajous scanning), a distance image is generated and output. That is, the distance image is updated every half cycle of the Lissajous scan. In the high-speed measurement mode, the distance measurement completion time for the target region, that is, the distance image generation cycle (update cycle) is halved compared to the normal measurement mode, and the frame rate is improved. Therefore, the high-speed measurement mode is usually selected when a frame rate is required.

  As described above, in the optical distance measuring device 1 according to the present embodiment, the drive unit 7 that swings and drives the inner movable unit 55 (light reflection surface 56) of the two-dimensional galvanometer mirror 50 as the optical scanning unit 5 changes the phase difference. A unit 72 and an amplitude changing unit 73 are provided. In response to the mode selection command, the phase difference changing unit 72 calculates a phase difference between the first drive signal for swinging the inner movable unit 55 in the horizontal direction and the second drive signal for swinging the inner movable unit 51 in the vertical direction. The amplitude changing unit 73 changes the swing amplitude of the inner movable unit 55 (the light reflecting surface 56) by adjusting the magnitudes of the first drive signal and the second drive signal in accordance with the mode selection command. The light source unit 9 emits pulsed light at a timing set in advance according to the mode selection command. As a result, the optical distance measuring device 1 can operate in any one of the normal measurement mode, the detailed measurement mode, the partial detailed mode, and the high-speed measurement mode. 1 can be operated.

  Incidentally, the optical distance measuring device 1 according to the above-described embodiment is configured to be operable in the normal measurement mode, the detailed measurement mode, the partial detailed mode, or the high-speed measurement mode, but is limited to those that can operate in all these operation modes. Instead of this, it may be configured to be operable in two or three operation modes appropriately combined. In other words, the driving unit 7 does not necessarily include both the phase difference changing unit 72 and the amplitude changing unit 73, and may include at least one.

  Further, the phase difference between the first drive signal and the second drive signal in each operation mode, the emission timing (number of measurements) of the pulsed light by the light source unit 9 are merely examples, and can be set as appropriate. That is, when it is desired to increase the measurement position in the target area, the phase difference between the first drive signal and the second drive signal is changed to increase the density of the Lissajous scanning trajectory in the target area and emit pulsed light. What is necessary is just to adjust a timing suitably and to increase the measurement position in an object area | region. For example, in the normal measurement mode, the phase difference between the first drive signal and the second drive signal is π / 4 (rad), in the detailed measurement mode, the phase difference is π / 2 (rad), and in the high-speed measurement mode, the above-described phase difference is set. The phase difference may be 0 (rad). In the partial detailed mode, the phase difference may be a value other than 0 (rad).

  Here, particularly in the detailed measurement mode and the partial detailed mode, the distance between adjacent measurement positions becomes small. For this reason, it is preferable to reduce the beam diameter of the pulsed light projected onto the target region in advance. Therefore, the light projecting optical system 93 may include a beam diameter changing unit that restricts the beam diameter of the laser light emitted from the light source 91 to at least one of the vertical direction and the horizontal direction. Such a beam diameter changing unit can be configured using, for example, at least one of a first cylindrical lens that narrows the beam in the vertical direction and a second cylindrical lens that narrows the beam in the horizontal direction, or a converging lens.

  For example, when the measurement position in the horizontal direction of the target region increases in the detailed measurement mode as compared with the normal measurement mode, the beam diameter changing unit causes the laser light emitted from the light source 91 by the light projecting optical system 93 to move in the horizontal direction. When the measurement position in the vertical direction of the target area increases in the aperture and detailed measurement mode as compared with the normal measurement mode, the laser light emitted from the light source 91 is narrowed in the vertical direction by the light projecting optical system 93. Of course, the laser light emitted from the light source 91 may be focused in the horizontal direction and the vertical direction. In this way, it is not necessary to change the light source to a light source having a small beam diameter, and the detailed measurement mode and the partial detailed mode can be effectively realized while using a conventional light source.

  The beam diameter may be changed using the warp of the light reflecting surface 56 instead of the beam changing unit. For example, the beam diameter can be reduced by making the light reflecting surface 56 concave. In this case, after collimating the beam diameter, it is preferable to pass through a collimator lens or the like to obtain parallel light. Even in this case, the detailed measurement mode and the partial detailed mode can be effectively realized while using the conventional light source.

  Furthermore, the beam diameter changing unit may change the beam diameter in accordance with a mode selection command input via the information input unit 3. For example, the inner movable portion 55 is provided with a heating element, and the inner movable portion 55 is configured so that the light reflecting surface 56 becomes a concave surface (or convex surface) by supplying current to the heating element according to the mode selection command and the heat generated by the heating element. It can be considered to be configured to be deformed.

  In the optical distance measuring device 1 according to the first embodiment, as shown in FIG. 3, even if the phase difference between the first drive signal and the second drive signal is changed, the interval of the Lissajous scanning trajectory is the target region. In the vicinity of the center, the roughness is rougher than that near the upper and lower ends. Therefore, the optical distance measuring device may be configured to have at least two scanning trajectories near the center of the target region. In this way, it is possible to increase the measurement position by narrowing the interval of the scanning trajectory near the center of the target area, which is particularly effective in the detailed measurement mode. A modification of the optical distance measuring device 1 according to the first embodiment will be described below.

  FIG. 6 shows a main part of a first modification of the optical distance measuring device 1 according to the first embodiment. As shown in FIG. 6, in the first modification, the light source unit 9 includes a first light source 91 a and a second light source 91 b having different incident angles of pulsed light to the light reflecting surface 56 of the light scanning unit 5. The scanning range (A1) of pulsed light from the first light source 91a by the scanning unit 5 and the scanning range (A2) of pulsed light from the second light source 91b by the optical scanning unit 5 overlap in the vicinity of the center of the target region. It is configured.

  In this way, the scanning range (that is, the distance measurement possible range) by the optical scanning unit 5 is expanded, and in the portion where both scanning ranges overlap, the second between the scanning trajectory of the pulsed light from the first light source 91a. The scanning trajectory of the pulsed light from the light source 91b is filled, and the interval between the scanning trajectories near the center becomes close. Thereby, the measurement position in the vicinity of the center of the target area can be sufficiently secured. In this case, in order to avoid crosstalk, the first light source 91a and the second light source 91b are light sources having different wavelengths, or the emission timing of the pulsed light is made different between the first light source 91 and the second light source 91b. It is preferable.

  FIG. 7 shows a main part of a second modification of the optical distance measuring device 1 according to the first embodiment. As shown in FIG. 7, in the second modification, in the two-dimensional galvanometer mirror 50 as the optical scanning unit 5, not only the inner movable unit 55 but also the outer movable unit 53 is provided with a light reflecting surface 63, The light reflection surface 56 provided at 55 performs two-dimensional scanning (Lissajous scanning) of the pulse light, and the light reflection surface 63 provided at the outer movable portion 53 performs one-dimensional scanning.

  Specifically, for example, as illustrated in FIG. 7A, the light source unit 9 includes a first light source 91 a and a second light source 91 b, and the first light source 91 a is provided on the inner movable unit 55. The second light source 91b emits the pulsed light toward the light reflecting surface 63 provided on the outer movable portion 53, and the light reflecting surface 56 of the pulsed light from the first light source 91a is emitted. The scanning range (two-dimensional scanning) according to the above and the scanning range (one-dimensional scanning) of the light reflecting surface 63 of the pulsed light from the second light source 91b are overlapped in the vicinity of the center of the scanning range. Even in this case, the measurement position near the center of the target region can be increased.

  Further, as shown in FIG. 7B, one light source 91 emits pulsed light toward the light reflecting surface 56 provided on the inner movable portion 55 and the light reflecting surface 63 provided on the outer movable portion 53. The scanning range of the pulsed light from the light source 91 by the light reflection surface 56 (two-dimensional scanning) and the scanning range by the light reflection surface 63 (one-dimensional scanning) are configured to have an overlapping portion near the center of the scanning range. Also good.

Next, an optical distance measuring device according to a second embodiment of the present invention will be described.
FIG. 8 is a block diagram showing a schematic configuration of the optical distance measuring device according to the second embodiment of the present invention.
Similarly to the optical distance measuring device 1 according to the first embodiment, the optical distance measuring device 100 according to the second embodiment performs Lissajous scanning with pulsed light (laser pulse) in the target area to the object existing in the target area. The distance is measured (ranging), and a distance image based on the measurement result is generated and output (displayed). However, in the optical distance measuring device 100 according to the second embodiment, the frequency of the first drive signal and the frequency of the second drive signal are the same, and the phase difference between the first drive signal and the second drive signal is π / 2. The point fixed to (rad) is different from the optical distance measuring device 1 according to the first embodiment. In the following description, the same elements as those of the optical distance measuring device 1 according to the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The optical distance measuring device 100 according to the present embodiment is configured to be operable in a plurality of operation modes. As shown in FIG. 5, the optical distance measuring device 100 includes an information input unit 3, an electromagnetically driven optical scanning unit 5, and an optical scanning unit 5. A driving unit 107 for driving, a light source unit 9 for emitting pulsed light, a light receiving unit 11 for receiving reflected light of the emitted pulsed light, and a distance measuring unit 13 for measuring a distance to an object reflecting the pulsed light The image generation unit 15 generates a distance image based on the measurement result of the distance measurement unit 13, and the display unit 17 outputs (displays) the generated distance image. Here, the plurality of operation modes include “normal measurement mode”, “detailed measurement mode”, and “high-speed measurement mode”.

  The drive unit 107 supplies a drive signal (alternating current) to the optical scanning unit 5 to drive the inner movable unit 55 (and the outer movable unit 53) to swing. The drive unit 107 supplies a first drive signal to the first drive coil 57 and supplies a second drive signal to the second drive coil 58, and the magnitudes of the first drive signal and the second drive signal ( And an amplitude changing unit 109 that changes the swing amplitude of the inner movable portion 55 by adjusting the amplitude).

  The drive circuit 108 receives the magnitudes of the first and second drive signals from the amplitude changing unit 108 and supplies the first drive signal and the second drive signal having the inputted magnitudes to the optical scanning unit 5. However, in the present embodiment, as described above, the frequency of the first drive signal and the frequency of the second drive signal are the same, and the phase difference between the first drive signal and the second drive signal is π / 2 ( rad).

  The amplitude changing unit 109 changes the swing amplitude of the inner movable unit 55 of the optical scanning unit 5 by adjusting the magnitudes of the first drive signal and the second drive signal. However, the amplitude changing unit 109 of the present embodiment does not change (set) the magnitudes of the first drive signal and the second drive signal in accordance with the mode selection command, but the magnitudes of the first drive signal and the second drive signal. Change the thickness gradually. Thereby, the optical scanning unit 5 scans the pulsed light while changing the swing amplitude of the inner movable unit 55. Specifically, the amplitude changing unit 109 swings around the axis of the first torsion bars 52, 52 of the inner movable unit 55 (horizontal scanning amplitude) and swings around the axis of the second torsion bars 54, 54. While setting the amplitude (vertical scanning amplitude) to be the same, the magnitudes of the first drive signal and the second drive signal are set so as to gradually change both oscillation amplitudes as time elapses. Output to the drive circuit 108. That is, the amplitude changing unit 109 gradually changes the swing amplitude of the inner movable unit 55 over time while keeping the horizontal / vertical amplitude ratio of the inner movable unit 55 constant. The scanning amplitude of the pulsed light is increased at a constant rate and then decreased at a constant rate.

FIG. 9 shows a Lissajous scanning locus by the optical scanning unit 5 in the second embodiment.
In the present embodiment, the frequency of the first drive signal and the frequency of the second drive signal are the same, and the horizontal and vertical drive cycles of the inner movable portion 55 are constant. The phase difference between the first drive signal and the second drive signal is π / 2 (rad), and the horizontal / vertical amplitude ratio of the inner movable portion 55 is also constant. In this state, when the first drive signal and the second drive signal are gradually increased by the amplitude changing unit 109 and the swing amplitude of the inner movable unit 55 is increased at a constant rate, the Lissajous scanning locus is shown in FIG. A spiral line having a diameter that gradually increases from the center of the target region to the outside as illustrated. After that, when the first drive signal and the second drive signal are gradually reduced and the swing amplitude of the inner movable portion 55 decreases at a constant rate, the outer portion gradually moves from the outside toward the center as shown in FIG. The spiral becomes smaller in diameter. That is, in this embodiment, the spiral Lissajous scanning trajectory reciprocates in the target region in one cycle of the Lissajous scanning, and the Lissajous scanning trajectory (FIG. 9A) in the first half of the Lissajous scanning cycle and the Lissajous scanning. Most of the Lissajous scanning trajectory in the latter half of the cycle (FIG. 9B) follows the same path.

The operation of the optical distance measuring device 100 according to the second embodiment having the above configuration will be described.
When the mode selection command for selecting the normal measurement mode is input from the information input unit 3 or when the mode selection command is not input from the information input unit 3, the optical distance measuring device 100 operates in the normal measurement mode. In this normal measurement mode, pulsed light is emitted from the light source unit 9 at a timing (measurement position) preset for the normal measurement mode. In this case, the optical distance measuring device 100 performs distance measurement at each measurement position (measurement number = n4) on the scanning locus shown in FIGS. 9A and 9B, for example, every cycle of Lissajous scanning. A distance image for the target area is generated and output. That is, the distance image is updated every cycle of the Lissajous scan.

  When a mode selection command for selecting the detailed measurement mode is input from the information input unit 3, the optical distance measuring device 100 operates in the detailed measurement mode. In the detailed measurement mode, pulsed light is emitted from the light source unit 9 at a timing (measurement position) set in advance for the detailed measurement mode. In this case, the optical distance measuring device 100 is at each measurement position (measurement number = n5> n4, here n5 = 2 × n4) on the scanning locus shown in FIGS. 9A and 9B. Distance measurement is performed, and for example, a distance image for the target region is generated and output every two cycles of Lissajous scanning. That is, the distance image is updated every two cycles of Lissajous scanning. The detailed measurement mode is usually selected when a detailed distance measurement for the target area is required.

  When a mode selection command for selecting the high-speed measurement mode is input from the information input unit 3, the optical distance measuring device 100 operates in the high-speed measurement mode. In the high-speed measurement mode, pulsed light is emitted from the light source unit 9 at a timing (measurement position) set in advance for the high-speed measurement mode. Here, in the high-speed measurement mode, pulse light is emitted from the light source unit 9 at the same position during forward scanning of the target region (the first half of one cycle of Lissajous scanning) and during backward scanning (the second half of one cycle of Lissajous scanning). The In this case, the optical distance measuring device 100 performs distance measurement at each measurement position (measurement number = n6 <n4, here n6 = n4 / 2) on the scanning locus shown in FIG. A distance image for the target image is generated and output every half of the cycle, and the distance is measured at the same measurement position (measurement number = n6) on the scanning locus shown in FIG. A distance image for the target region is generated and output every 1/2 cycle of the Lissajous scan. That is, the distance image is updated every half cycle of the Lissajous scan. The high-speed measurement mode is usually selected when a frame rate is required.

  As described above, in the optical distance measuring device 100 according to the second embodiment, the driving unit 107 that swings the inner movable unit 55 (light reflecting surface 56) of the two-dimensional galvanometer mirror 50 as the optical scanning unit 5 includes the driving circuit 108. And an amplitude changing unit 109. The amplitude changing unit 109 gradually increases the swing amplitude of the inner movable unit 55 over time, and then gradually decreases it while keeping the horizontal / vertical swing amplitude ratio of the inner movable unit 55 constant. Further, the magnitudes of the first drive signal and the second drive signal are adjusted, and the drive circuit 108 outputs the first drive signal and the second drive signal having the same frequency with a phase difference π / 2. The light source unit 9 emits pulsed light at a timing set in advance according to the operation mode. As a result, the optical distance measuring device 100 can operate in any one of the normal measurement mode, the detailed measurement mode, and the high-speed measurement mode only by changing the emission timing of the pulsed light according to the operation mode. The optical distance measuring device 100 can be operated in a preferable operation mode according to the above. In the optical distance measuring device 100 according to the second embodiment, the changing speed of the swing amplitude of the inner movable unit 55 and the emission timing (number of measurements) of the pulsed light by the light source unit 9 can be set as appropriate. Of course, the section 9 (projection optical system 93) may include a beam diameter changing section.

  Incidentally, in the optical distance measuring devices 1 and 100 according to the first and second embodiments, the operation mode is changed according to the mode selection command input via the information input unit 3, but the operation is performed by another method. The mode may be changed. Some examples will be described below.

  The distance from the optical distance measuring device 1, 100 is set within a certain range (for example, between 1 m and 10 m) as the main distance measurement target space, and the operation is performed depending on whether or not an object exists in the distance measurement target space. The mode may be changed. For example, when the optical distance measuring device 1, 100 is operating in the normal measurement mode or the high-speed measurement mode, when an object enters the set distance measurement target space, the mode is changed to the detailed measurement mode, and the detailed measurement mode is operated. When no object is present in the distance measurement target space, the mode is changed to the normal measurement mode. If the state in which no object exists in the distance measurement target space continues further, the mode is changed to the high-speed measurement mode. In this case, for example, an operation mode determination unit that inputs a measurement result by the distance measurement unit 13 and determines an operation mode based on the input measurement result is provided. In the optical distance measurement device 1 according to the first embodiment, The determination result of the operation mode determination unit is output to the phase difference changing unit 72 and the light source control unit 92, and the second optical distance measuring device 100 is configured to output the determination result of the operation mode determination unit to the light source control unit 92. That's fine.

  Further, the operation mode may be changed according to the distance to the object in the target area. For example, the optical distance measuring devices 1 and 100 first operate in the normal measurement mode, and change to the detailed measurement mode when all of the objects in the target area are located at a position away from the preset first distance. When at least one of the objects in the target area is present at a position closer than a preset second distance (<first distance), the high-speed measurement mode is changed. Further, when at least one object existing in the target area is within the first distance when operating in the detailed measurement mode, the mode is changed to the normal measurement mode, and within the target area when operating in the high-speed measurement mode. When all the objects existing in are separated by the second distance or more, the normal measurement mode is changed. That is, the optical distance measuring devices 1 and 100 operate in the high-speed measurement mode if at least one of the objects in the target area is closer than the second distance, and all the objects in the target area are separated from the first distance. If it is in the specified position, it operates in the detailed measurement mode, otherwise it operates in the normal measurement mode. Even in this case, an operation mode determination unit that determines an operation mode based on the measurement result input from the distance measurement unit 13 is provided. In the optical distance measuring device 1 according to the first embodiment, the determination result of the operation mode determination unit is determined. What is necessary is just to comprise so that it may output to the phase difference change part 72 and the light source control part 92, and the determination result of an operation mode determination part may be output to the light source control part 92 in the 2nd optical distance measuring device 100.

  Furthermore, when the optical distance measuring devices 1 and 100 are attached to a moving body such as an automobile, the operation mode may be changed according to the moving speed of the moving body. For example, the optical distance measuring devices 1 and 100 first operate in the normal measurement mode, and when the moving speed of the moving body (= the moving speed of the optical distance measuring device) is higher than the preset first speed, the high speed measurement is performed. When the moving speed of the moving body is lower than the preset second speed (<first speed), the mode is changed to the detailed measurement mode. When the moving speed of the moving object becomes equal to or higher than the second speed when operating in the detailed measurement mode, the mode is changed to the normal measurement mode, and the moving speed of the moving object is equal to or lower than the first speed when operating in the high-speed measurement mode. Then, change to normal measurement mode. That is, the optical distance measuring devices 1 and 100 operate in the high-speed measurement mode when the moving speed of the moving body is higher than the first speed, and in the detailed measurement mode when the moving speed of the moving body is lower than the second speed. Operates, otherwise it operates in normal measurement mode. In this case, the optical distance measuring device 1,100 is provided with a speed input unit for inputting a moving speed from the speed sensor or the moving body, and an operation mode determining unit for determining an operating mode based on the moving speed of the moving body, In the optical distance measuring device 1 according to the first embodiment, the determination result of the operation mode determination unit is output to the phase difference changing unit 72 and the light source control unit 92, and in the second optical distance measurement device 100, the determination result of the operation mode determination unit. May be output to the light source control unit 92.

  Although it is possible to change the operation mode in accordance with the moving speed of the measurement object, in this case, a mode selection command selected in accordance with the moving speed of the measurement object is input from the information input unit 3. do it.

  DESCRIPTION OF SYMBOLS 1 ... Optical distance measuring device, 3 ... Information input part, 5 ... Optical scanning part, 7 ... Drive part, 9 ... Light source part, 11 ... Light receiving part, 13 ... Distance measuring part, 15 ... Image generation part, 17 ... Display part , 50 ... Two-dimensional galvanometer mirror, 51 ... Fixed part, 52 ... First torsion bar, 53 ... Outer movable part, 54 ... Second torsion bar, 55 ... Inner movable part, 57 ... First drive coil, 58 ... Second Drive coil, 71 ... Drive circuit, 72 ... Phase difference changing unit, 73 ... Amplitude changing unit, 91 ... Light source, 92 ... Light source control unit, 93 ... Projecting optical system 93, 100 ... Optical distance measuring device, 107 ... Drive unit , 108 ... Drive circuit, 109 ... Amplitude changing unit

Claims (17)

A movable part having a light reflecting surface is formed so as to be able to swing in a first direction and a second direction orthogonal to each other, and the light incident on the light reflecting surface as a result of the swinging of the movable part is Lissajous in the target region. An optical scanning unit capable of scanning;
A first drive signal for swinging the movable portion in the first direction and a second drive signal for swinging the movable portion in the second direction are supplied to the optical scanning portion to drive the movable portion to swing. A drive unit;
A light source unit that emits pulsed light toward the light reflecting surface;
A light receiving unit that receives the reflected light reflected by the object existing in the target region, the pulsed light emitted from the light source unit;
A distance measuring unit that measures the distance of the object based on the emission timing of the pulsed light by the light source unit and the reception timing of the reflected light by the light receiving unit,
The drive unit is configured to change a phase difference between the first drive signal and the second drive signal, and adjust the magnitudes of the first drive signal and the second drive signal to move the movable unit. An optical distance measuring device including at least one of amplitude changing units for changing the swing amplitude of the unit.   2. The light according to claim 1, wherein the phase difference changing unit changes a phase difference between the first drive signal and the second drive signal to make the interval of the Lissajous scanning locus by the optical scanning unit dense or coarse. Distance measuring device. An information input unit for inputting operation-related information related to the operation of the optical distance measuring device;
The phase difference changing unit changes the phase difference between the first drive signal and the second drive signal based on operation-related information input via the information input unit. The optical distance measuring device described.   The optical distance measuring device according to claim 1, wherein the phase difference changing unit changes a phase difference between the first drive signal and the second drive signal based on a measurement result by the distance measuring unit. .   The optical distance measuring device according to any one of claims 1 to 4, wherein the amplitude changing unit changes a swing amplitude of the movable unit to reduce or increase a Lissajous scanning range. An information input unit for inputting operation-related information related to the operation of the optical distance measuring device;
The optical distance measuring device according to claim 1, wherein the amplitude changing unit changes a swing amplitude of the movable unit based on operation-related information input via the information input unit. .   The said light source part is provided with the light source control part which controls the emission timing of the said pulsed light based on the measurement result by the said ranging part or the operation | movement relevant information input via the said information input part. The optical distance measuring device according to any one of the above.   The optical distance measuring device according to claim 1, wherein the light source unit includes a beam diameter changing unit that narrows a beam diameter of pulsed light emitted toward the light reflecting surface.   9. The optical distance measuring device according to claim 1, further comprising an image generation unit configured to generate a distance image for the target region using a measurement result obtained by the distance measurement unit as a pixel value. 10. The drive unit supplies the first drive signal and the second drive signal to the optical scanning unit so that the scan locus in the first half of the Lissajous scanning cycle and the scan locus in the second half follow the same path,
10. The optical measurement according to claim 1, wherein the light source unit emits the pulsed light at a timing at which the same measurement position of the target region is scanned in the first half and the second half of the Lissajous scanning cycle. Distance device.   When the phase difference changing unit changes the phase difference between the first drive signal and the second drive signal, the scanning trajectory in the first half and the scanning trajectory in the second half of the Lissajous scanning cycle are the same in the reverse scanning direction. The optical distance measuring device according to claim 10.   The swirl-like Lissajous scanning trajectory reciprocates in the target region in the Lissajous scanning cycle by the amplitude changing unit gradually increasing the swing amplitude of the movable unit and then gradually decreasing the swinging amplitude. The optical distance measuring device described in 1.   The optical distance measuring device according to claim 10, wherein the image generation unit generates a distance image for the target region every ½ cycle of the Lissajous scanning. The optical scanning unit
A frame-shaped fixing part;
An outer movable portion disposed inside the fixed portion and supported by a pair of first torsion bars so as to be swingable;
An inner movable part that is disposed inside the outer movable part, and is pivotably supported by a pair of second torsion bars whose axial directions are orthogonal to each other with the first torsion bar;
A first light reflecting surface formed on the inner movable part,
The optical distance measuring device according to claim 1, wherein the pulsed light emitted from the light source unit and incident on the first light reflecting surface is Lissajous scanned within the target region. The optical scanning unit further includes a second light reflecting surface formed on the outer movable unit,
The pulsed light emitted from the light source unit and incident on the first light reflecting surface is Lissajous scanned within the target region, while the pulsed light emitted from the light source unit and incident on the second light reflecting surface is the target. The optical distance measuring device according to claim 14, wherein one-dimensional scanning is performed within the region. The light source unit has two light sources,
The optical distance measuring device according to claim 14, wherein an incident angle of the pulsed light emitted from each light source to the first light reflecting surface is different. The light source unit has two light sources,
The optical distance measuring device according to claim 15, wherein one light source emits pulsed light toward the first light reflecting surface, and the other light source emits pulsed light toward the second light reflecting surface.

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