JP2018004257A - Optical scanner, object detection device, sensing device and traveling body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical scanning device capable of achieving miniaturization, long life and low power consumption. A light source, a coupling lens, a synchronization lens, a synchronization detection photodetector, a light source drive unit, a synchronization signal generation unit, a reflection mirror, an optical deflector, and the like are included. The light source driving section drives the light source by a first driving method and a second driving method having a light emission pattern different from the first driving method outside the scanning area, and within the scanning area, the first driving method and the second driving method. The light source is driven by a third driving method which is different from the second driving method in the amount of emitted light. The first driving method is a light emission pattern synchronized with the scanning period of the synchronous detection photodetector, and the second driving method is specialized for detecting a light reception signal from the synchronous detection photodetector. It is the emitted light pattern. [Selection diagram] Fig. 28

Description

  The present invention relates to an optical scanning device, an object detection device, a sensing device, and a traveling body, and more specifically, an optical scanning device that scans a scanning region with light, an object detection device having the optical scanning device, and the object detection device. The present invention relates to a sensing device having a traveling body including the sensing device.

  In recent years, development of an object detection device that detects an object using light has been actively performed (for example, see Patent Documents 1 to 6).

  This object detection device detects an object by optically scanning a detection region with an optical scanning device and receiving light reflected by the object.

  In recent years, there has been an increasing demand for object detection devices that are small in size, long in life, and low in power consumption. For this purpose, it is effective to reduce the size, extend the life, and reduce the power consumption of the optical scanning device used in the object detection device. However, in the conventional optical scanning device, it has been difficult to satisfy all of downsizing, long life, and low power consumption.

  The present invention is an optical scanning device that scans a predetermined scanning region with light, and includes a light source, a light source driving device that drives the light source, an optical deflector that deflects light from the light source, and the scanning region. A light detector for determining a timing to start scanning, and the light detector and the scanning region are sequentially scanned by one scanning by the light deflector, and the light source driving device is located outside the scanning region. Then, the light source is driven by a second driving method having a light emission pattern different from that of the first driving method and the first driving method, and the first driving method and the second driving method are used in a scanning region. Is an optical scanning device that drives the light source by a third driving method having different light emission amounts.

  According to the optical scanning device of the present invention, it is possible to reduce the size, extend the lifetime, and reduce the power consumption.

1 is an external view of a vehicle equipped with a laser radar according to an embodiment of the present invention. It is a block diagram for demonstrating the structure of the monitoring apparatus which concerns on one Embodiment of this invention. It is a figure for demonstrating the structure of a laser radar. It is a figure for demonstrating a light emission system. It is a figure for demonstrating a synchronous signal generation part. It is a figure for demonstrating the relationship between a received light signal and a synchronizing signal. It is a figure for demonstrating an optical deflection system. It is a figure for demonstrating an optical deflector. It is a figure for demonstrating the light for a synchronous detection. It is FIG. (1) for demonstrating the advancing direction of a detection light. It is FIG. (2) for demonstrating the advancing direction of detection light. FIG. 10 is a third diagram for explaining the traveling direction of detection light; It is a figure for demonstrating a detection area. It is a figure for demonstrating a light source drive signal. It is a figure for demonstrating a synchronous detection range. It is a figure for demonstrating a photon detection system. It is FIG. (1) for demonstrating the incident direction of the reflected light from an object. It is FIG. (2) for demonstrating the incident direction of the reflected light from an object. It is FIG. (3) for demonstrating the incident direction of the reflected light from an object. It is a figure for demonstrating a detection signal production | generation part. It is a figure for demonstrating the relationship between a received light signal and a detection signal. It is a figure for demonstrating the distance measurement to the object in an object information acquisition part. It is a figure for demonstrating the positional relationship of a light source and a light receiver. It is a timing chart for demonstrating the relationship between a light source drive signal, a synchronous detection range, and a synchronous signal. It is a figure for demonstrating the relationship of three drive methods. It is a timing chart for demonstrating the specific example 1. 10 is a flowchart for explaining a specific example 1; It is a timing chart for demonstrating the specific example 2. 10 is a timing chart for explaining division example 1; It is a figure for demonstrating the relationship between the lighting timing in a division example 1, and a synchronous detection period. 10 is a timing chart for explaining a division example 2; It is a figure for demonstrating the relationship between the lighting timing in a division example 2, and a synchronous detection period. 6 is a timing chart for explaining Comparative Example 1; It is a figure for demonstrating the relationship between the lighting timing in a comparative example 1, and a synchronous detection period. 10 is a timing chart for explaining Comparative Example 2; It is a figure for demonstrating the relationship between the lighting timing in a comparative example 2, and a synchronous detection period. 10 is a timing chart for explaining Comparative Example 3; It is a figure for demonstrating the relationship between the lighting timing in a comparative example 3, and a synchronous detection period. 10 is a timing chart for explaining a comparative example 4; It is a figure for demonstrating the relationship between the lighting timing in a comparative example 4, and a synchronous detection period. It is a timing chart (the 1) for explaining the case where the maximum number of times of synchronous lighting until a synchronous pulse is detected is set up in synchronous search mode. FIG. 10 is a timing chart for explaining a case where the number of times of detecting synchronous pulses continuously in order to return to the measurement mode is set in the synchronous search mode in the synchronous search mode. 12 is a timing chart (No. 2) for explaining a case where the maximum number of times of synchronous lighting until a synchronization pulse is detected is set in the synchronous search mode. It is a timing chart for demonstrating the case where pulse lighting is not carried out in the first scan which returned to the measurement mode. It is a timing chart for demonstrating measurement data transfer and invalid data transfer information. It is a figure for demonstrating that a synchronous lighting time and a synchronous lighting period are variable. It is a block diagram for demonstrating the structure of an audio | voice / alarm generator.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows an appearance of a vehicle 1 as a traveling body equipped with a laser radar 20 as an object detection device according to an embodiment.

  The laser radar 20 emits laser light, receives reflected light (scattered light) from an object (for example, a preceding vehicle, a stopped vehicle, an obstacle, a pedestrian, etc.) and measures the distance to the object. Laser radar. The laser radar 20 is supplied with electric power from, for example, a battery (storage battery) of the vehicle 1.

  Here, as an example, the laser radar 20 is attached in the vicinity of a license plate in front of the vehicle 1. In this specification, an XYZ three-dimensional orthogonal coordinate system is used, and the direction orthogonal to the road surface is described as the Z-axis direction, and the forward direction of the vehicle 1 is described as the + X direction. An area where the object can be detected by the laser radar 20 is referred to as a “detection area”. Furthermore, a direction parallel to the Z axis is also referred to as a “height direction” or a “vertical direction”, and a direction orthogonal to the Z axis is also referred to as a “horizontal direction”.

  As shown in FIG. 2 as an example, the vehicle 1 is provided with a display device 30, a monitoring control device 40, a memory 50, a sound / alarm generating device 60, and the like. These are electrically connected via a bus 70 capable of transmitting data.

  Here, the laser radar 20, the display device 30, the monitoring control device 40, the memory 50, and the voice / alarm generating device 60 constitute the monitoring device 10 as a sensing device. That is, the monitoring device 10 is mounted on the vehicle 1. The monitoring device 10 is electrically connected to the main controller of the vehicle 1.

  As shown in FIG. 3 as an example, the laser radar 20 includes an optical scanning device 200, a light detection system 202, an object information acquisition unit 203, and the like. And these are accommodated in the housing | casing.

  The optical scanning device 200 includes a light emission system 201, a light deflection system 204, and the like. Here, the light emission system 201 is disposed on the + Z side of the light detection system 202.

  As shown in FIG. 4 as an example, the light emission system 201 includes a light source 21, a coupling lens 22, a synchronization lens 23, a synchronization detection photodetector 24, a light source drive unit 25, a synchronization signal generation unit 26, and the like. doing.

  The light source 21 has a semiconductor laser (edge emitting laser) and is turned on and off by a light source drive signal from the light source drive unit 25. Here, the light source 21 is disposed so as to emit light in the + X direction.

  The coupling lens 22 is disposed on the + X side of the light source 21 and makes light emitted from the light source 21 parallel light or divergent light slightly diverged. Here, a plano-convex lens is used as the coupling lens 22. The light that has passed through the coupling lens 22 is light emitted from the light emission system 201. In place of the coupling lens 22, a coupling optical system having an equivalent function and including a plurality of optical elements may be used.

  The synchronization lens 23 is disposed on the optical path of the synchronization detection light incident on the light emission system 201 and condenses the synchronization detection light. The synchronization detection light will be described later.

  The synchronization detection light detector 24 is disposed at a position where the synchronization detection light is condensed via the synchronization lens 23. The synchronization detection photodetector 24 outputs a signal (light reception signal) corresponding to the amount of received light to the synchronization signal generation unit 26.

  The synchronization signal generation unit 26 generates a synchronization signal from the received light signal and outputs the synchronization signal to the light source driving unit 25. As shown in FIG. 5 as an example, the synchronization signal generator 26 has two functions of signal amplification of the light reception signal and timing detection from the light reception signal.

  Signal amplification of the received light signal is performed using a signal amplifier such as an amplifier. For timing detection from the received light signal, a comparator such as a comparator is used to detect the rising timing of the signal waveform that is equal to or higher than a certain output level (threshold level) in the received light signal. That is, the synchronization signal generation unit 26 outputs a logic signal obtained by binarizing the received light signal using a comparator as a synchronization signal (see FIG. 6). Hereinafter, for the sake of convenience, the high level portion of the synchronization signal is also referred to as a “synchronization pulse”.

  The light source driving unit 25 refers to the synchronization signal from the synchronization signal generating unit 26 and generates a light source driving signal for driving the light source 21. For example, the light source driving unit 25 includes a capacitor connected to be able to supply current to the light source 21, a transistor for switching conduction / non-conduction between the capacitor and the light source 21, and a charging device for charging the capacitor. Etc.

  When detecting the synchronization pulse in the synchronization signal from the synchronization signal generation unit 26, the light source driving unit 25 determines that the synchronization detection light detector 24 has received the synchronization detection light.

  The light deflection system 204 is disposed on the + X side of the light emission system 201. As shown in FIG. 7 as an example, the optical deflection system 204 includes a reflection mirror 31, an optical deflector 32, and the like.

  The reflection mirror 31 folds the light emitted from the light emission system 201 toward the optical deflector 32. The reflection mirror 31 is provided to reduce the size of the laser radar 20 by folding the optical path.

  The optical deflector 32 includes a rotating mirror and a driving mechanism for driving the rotating mirror to rotate. As an example, as shown in FIG. 8, the rotating mirror has two reflecting surfaces and rotates around a rotation axis parallel to the Z axis. The drive mechanism is controlled by the object information acquisition unit 203. Here, the rotating mirror is set to rotate clockwise when viewed from the + Z side. Each reflecting surface is parallel to the Z-axis direction.

  Note that the number of reflecting surfaces in the rotating mirror is not limited to two, and may be one or three or more. It is also possible to switch the scanning region with respect to the Z-axis direction by setting the at least two reflecting surfaces to different inclination angles with respect to the rotation axis.

  Returning to FIG. 7, the optical deflector 32 is disposed on the optical path of the light emitted from the light emission system 201 and reflected by the reflection mirror 31. That is, the light emitted from the light emission system 201 and reflected by the reflection mirror 31 is deflected by the light deflector 32.

  Therefore, the light emitted from the light source 21 is shaped into light having a predetermined beam profile by the coupling lens 22, reflected by the reflection mirror 31, and deflected around the Z axis by the optical deflector 32.

  As an example, as shown in FIG. 9, when the rotation angle of the rotating mirror is a predetermined angle, the light deflected by the optical deflector 32 returns to the reflecting mirror 31, is reflected by the reflecting mirror 31, and is synchronized with the synchronizing lens 23. The light is received by the synchronization detection photodetector 24. At this time, the light reflected by the reflection mirror 31 is the synchronization detection light.

  When the rotating mirror further rotates, the light deflected by the optical deflector 32 goes to the detection area. Hereinafter, the light deflected by the optical deflector 32 and directed to the detection region is also referred to as “detection light”.

  In the plane orthogonal to the Z-axis direction, the traveling direction of the detection light varies depending on the rotation angle of the rotating mirror (see FIGS. 10 to 12). That is, the detection area is scanned in the −Y direction by the detection light as the rotating mirror rotates (see FIG. 13).

  Then, in a plane orthogonal to the Z axis, an angle φ formed by the traveling direction of the detection light toward the + Y side end of the detection region and the traveling direction of the detection light toward the −Y side end of the detection region (FIG. 13). (Referred to as scanning angle). In other words, the detection region in the plane orthogonal to the Z-axis direction is a scanning region (predetermined scanning region) defined by the scanning angle φ.

  As described above, the synchronization detection photodetector 24 and the detection region are sequentially scanned by one scan by the one reflecting surface of the rotating mirror.

  Therefore, when the rotating mirror rotates, a synchronizing pulse is output from the synchronizing signal generator 26 every time the light reflected by each reflecting surface of the rotating mirror is received by the synchronization detection photodetector 24. That is, a synchronization pulse is periodically output from the synchronization signal generator 26.

  By turning on the light source 21 so that the light from the rotating mirror is incident on the synchronization detection photodetector 24, the rotation timing of the rotation mirror can be known from the light reception timing at the synchronization detection photodetector 24. . Hereinafter, for convenience, lighting the light source 21 for synchronization detection is also referred to as “synchronous lighting”.

  Therefore, the detection region can be optically scanned by turning on the light source 21 in a synchronized manner and turning on the light source 21 after a predetermined time (Td) has elapsed since the synchronization pulse was detected (see FIG. 14). That is, the detection region can be optically scanned by turning on the light source 21 in a period before and after the timing at which light enters the synchronization detection photodetector 24. Hereinafter, for the sake of convenience, the pulse lighting when optically scanning the detection region is also referred to as “scanning pulse lighting”.

  At this time, the amount of emitted light in synchronous lighting and the amount of emitted light in scanning pulse lighting are controlled so as to satisfy the relationship of (the amount of emitted light in synchronous lighting) <(the amount of emitted light in scanning pulse lighting).

  Hereinafter, a design period in which the light emitted from the light source 21 is received by the synchronization detection photodetector 24 when the rotating mirror is rotating is also referred to as a “synchronization detection range” (FIG. 15). reference).

  When receiving the object information acquisition start request from the monitoring control device 40, the object information acquisition unit 203 drives the drive mechanism of the optical deflector 32 and transmits the drive start request of the light source 21 to the light source drive unit 25. As a result, the light source driving unit 25 starts driving the light source 21.

  When the object information acquisition unit 203 receives an object information acquisition end request from the monitoring control device 40, the object information acquisition unit 203 transmits a drive end request for the light source 21 to the light source driving unit 25. Thereby, the light source driving unit 25 finishes driving the light source 21.

  By the way, if there is an object in the detection area, a part of the light emitted from the laser radar 20 and reflected by the object returns to the laser radar 20. Hereinafter, for convenience, the light reflected by the object and returning to the laser radar 20 is also referred to as “reflected light from the object”.

  The light reflected from the object and deflected in the direction toward the reflection mirror 31 by the optical deflector 32 is reflected by the reflection mirror 31 and enters the light detection system 202.

  As shown in FIG. 16 as an example, the light detection system 202 includes an imaging optical system 41, a light receiver 42, a detection signal generation unit 43, and the like.

  The imaging optical system 41 is disposed on the optical path of the reflected light from the object reflected by the reflecting mirror 31, and collects the light (see FIGS. 17 to 19). Here, the imaging optical system 41 is composed of two lenses, but is not limited to this. For example, the imaging optical system 41 may be composed of one lens, or may be composed of three or more lenses. A mirror optical system may be used as the imaging optical system 41.

  The light receiver 42 receives light via the imaging optical system 41 and outputs a signal (light reception signal) corresponding to the amount of received light to the detection signal generation unit 43.

  As the light receiving element of the light receiver 42, PD (photodiode), APD (avalanche photodiode), SPAD (single photo avalanche diode) which is a Geiger mode APD, or the like can be used. Since APD and SPAD are highly sensitive to PD, they are advantageous in terms of detection accuracy and detectable distance.

  The detection signal generation unit 43 generates a detection signal from the received light signal and outputs the detection signal to the object information acquisition unit 203. As shown in FIG. 20 as an example, the detection signal generation unit 43 has two functions of signal amplification of a light reception signal and timing detection from the light reception signal.

  Signal amplification of the received light signal is performed using a signal amplifier such as an amplifier. For timing detection from the received light signal, a comparator such as a comparator is used to detect the rising timing of the signal waveform that is equal to or higher than a certain output level (threshold level) in the received light signal. That is, the detection signal generation unit 43 outputs a logic signal obtained by binarizing the received light signal using a comparator as a detection signal (see FIG. 21). Hereinafter, for the sake of convenience, the high level portion of the detection signal is also referred to as a “detection pulse”.

  When the object information acquisition unit 203 detects a detection pulse in the detection signal from the detection signal generation unit 43, the object information acquisition unit 203 determines that the light receiver 42 has received reflected light from the object.

  As an example, as shown in FIG. 22, the distance from the elapsed time tk from the light emission timing of the light source 21 to the light reception timing of the light receiver 42 to the object is obtained. At this time, the object information acquisition unit 203 may perform a correction process as necessary.

  It is also possible to measure the time tk by A / D converting the waveforms of the light emission pulse and the light reception pulse into digital data, and calculating the correlation between the output signal of the light source 21 and the output signal of the light receiver 42. is there.

  The light emission system 201 and the light detection system 202 are arranged so as to overlap each other in the Z direction, and the light deflection system 204 is shared by the light emission system 201 and the light detection system 202 (see FIG. 23). In this case, the relative positional shift between the irradiation range of the light from the light source 21 on the object and the receivable range of the light receiver 42 can be reduced, and stable object detection can be realized.

  Next, the synchronization detection timing will be described.

  When the rotating mirror rotates stably, as shown in FIG. 24 as an example, a synchronization pulse is output from the synchronization signal generation unit 26 at a constant period, so that the next synchronization detection timing can be predicted. . Hereinafter, this cycle is also referred to as a “synchronization detection cycle”.

  In this case, the timing for performing the synchronous lighting is as follows: the synchronous lighting is started at the timing slightly before the next synchronous detection timing after the synchronous detection, that is, the timing after the time slightly shorter than the synchronous detection cycle. Synchronous detection can be performed.

  However, the synchronization detection timing cannot be predicted at the time of startup and when synchronization is lost for some reason. At this time, if the rotation of the rotating mirror is stable, the synchronization detection timing can be searched for by synchronously lighting the light source 21 continuously during the synchronization detection period at the longest.

  Hereinafter, the driving method in which the synchronous detection timing is known and the synchronous lighting is started at a timing slightly after a time shorter than the synchronous detection cycle is also referred to as a “first driving method”. Also, a driving method in which the scanning pulse is lit after a predetermined time (Td) has elapsed since the detection of the synchronization pulse in order to optically scan the detection region is also referred to as a “third driving method”.

  Here, the light emission control method of the light source 21 in this embodiment is demonstrated.

  First, it is stored whether or not a synchronization pulse has been detected in the previous scan. That is, it stores whether or not the synchronization detection timing detected periodically is known.

  When there is synchronization detection information at the time of normal measurement, the scanning pulse is lit on the scanning region based on the detection timing of the synchronization pulse. Also, with the sync pulse detection timing as a reference, synchronous lighting starts at a timing slightly before the next sync pulse detection timing, that is, at a timing outside the scanning region after a time slightly shorter than the sync detection cycle. Turns off when is detected.

  Next, when “synchronization detection information is not found” in which a synchronization pulse is not detected even when a time slightly longer than the synchronization detection period has elapsed, the measurement mode is shifted to the synchronization search mode. And after predetermined time passes, synchronous lighting is started and the detection timing of a synchronous pulse is searched. The driving method of the light source 21 at this time is referred to as a “second driving method”.

  The relationship between the three driving methods is shown in FIG. That is, the second driving method is selected in the synchronous search mode, and the first driving method and the third driving method are selected in the measurement mode. The amount of light emitted by the third drive method is larger than the amount of light emitted by the first drive method and the amount of light emitted by the second drive method.

  An embodiment in the case of shifting from the measurement mode to the synchronous search mode without detecting a synchronization pulse during object detection will be described. Here, as an example, it is assumed that the rotation speed of the rotating mirror is 2000 [rpm], the number of surfaces is 2 [surfaces], that is, the synchronization detection period is 15 [msec].

<Specific example 1>
First, specific example 1 of synchronization detection in the synchronization search mode will be described with reference to FIG. In the first scan from the left, a synchronization pulse is normally detected at a synchronization detection period of 15 [msec]. Then, on the basis of the detection timing, the scanning pulse lighting is started after a lapse of time until the rotating mirror rotates to the position of the first measurement point. When the scanning pulse lighting at the final measurement point of the scanning is completed, the light emission amount of the light source 21 is switched from “the light emission amount in the scanning pulse lighting” to “the light emission amount in the synchronous lighting”.

  Then, after the time slightly shorter than the synchronization detection period has elapsed from the synchronization detection timing of this scanning, the synchronous lighting in the measurement mode is started. Thereafter, the synchronization pulse of the second scan is detected.

  However, if a synchronization pulse is not detected even if a time slightly longer than the synchronization detection period elapses in the third scan, the mode shifts from the measurement mode to the synchronization search mode.

  In this case, scanning pulse lighting is not performed until the measurement mode is restored. This is because the position at which the scan pulse is lit cannot be specified, so it cannot be measured at the exact position of the target, and when the rotating mirror is stopped, high output light is repeatedly emitted to the same position. Because there is.

  Synchronous lighting is started after an arbitrary time has elapsed since the transition to the synchronous search mode. In this case, the light source 21 is continuously lit. If the synchronization detection function is normal, the synchronization pulse is detected within 15 [msec] from the start of the synchronous lighting. Hereinafter, for convenience, synchronous lighting by continuous lighting is also referred to as “continuous synchronous lighting”.

  Next, an example in which a synchronization pulse is detected in the synchronous search mode and the measurement mode is returned from the synchronous search mode will be described.

  When the synchronization pulse is detected, the measurement mode is returned from the synchronous search mode, and the light emission amount of the light source 21 is switched from “the light emission amount in the synchronous lighting” to “the light emission amount in the scanning pulse lighting”. Thereafter, the same control as in the first scan is performed.

  In this way, the light source driving unit 25 performs switching between “light emission amount in scanning pulse lighting” and “light emission amount in synchronous lighting” and switching the light emission pattern in conjunction with each other.

  A flowchart of processing performed by the light source driving unit 25 at this time is shown in FIG.

  In the first step S401, the light emission amount of the light source 21 is switched. Here, the “light emission amount in synchronous lighting” is switched.

  In the next step S403, synchronous lighting is performed by the first driving method.

  In the next step S405, it is determined whether or not a synchronization pulse has been detected. If no sync pulse is detected, the determination here is denied and the process proceeds to step S407.

  In step S407, it is determined whether a predetermined time has elapsed. If the predetermined time has not elapsed, the determination here is denied and the process returns to step S403. On the other hand, if the predetermined time has elapsed, the determination here is affirmed and the process proceeds to step S409.

  In step S409, synchronous lighting is performed by the second driving method.

  In the next step S411, it is determined whether or not a synchronization pulse has been detected. If a synchronization pulse is detected, the determination here is affirmed and the routine returns to step S403. On the other hand, if the synchronization pulse is not detected, the determination here is denied and the process proceeds to step S413.

  In step S413, it is determined whether a predetermined time has elapsed. If the predetermined time has not elapsed, the determination here is denied and the process returns to step S409. On the other hand, if the predetermined time has elapsed, the determination here is affirmed and the process is terminated.

  If a synchronization pulse is detected in step S405, the determination in step S405 is affirmed and the process proceeds to step S415.

  In step S415, the amount of light emitted from the light source 21 is switched. Here, it is switched to “amount of emitted light in scanning pulse lighting”.

  In the next step S417, the scan pulse is turned on by the third driving method.

  In the next step S419, it is determined whether or not one scan is completed. If one scan is not completed, the determination here is denied and the process returns to step S417. On the other hand, if one scan is completed, the determination here is affirmed, and the process returns to step S401.

<Specific example 2>
Next, specific example 2 of synchronization detection in the synchronization search mode will be described with reference to FIG. In this specific example 2, in the synchronous search mode, the synchronous lighting is performed at a cycle different from an integer multiple or a fraction of the synchronous detection cycle so as to be asynchronous with the synchronous detection cycle, and at least one scan is performed. Detect sync pulse.

  In FIG. 28, since a synchronization pulse is not detected even if a time slightly longer than the synchronization detection cycle has elapsed in the second scan, the mode shifts from the measurement mode to the synchronization search mode. Scan pulse lighting is not performed during the period from the transition to the synchronous search mode to the return to the measurement mode.

  After an arbitrary time has elapsed from the timing of shifting to the synchronous search mode, synchronous lighting with a lighting time of 3 [msec] is started at a cycle of 18 [msec]. Hereinafter, the period of synchronous lighting in the synchronous search mode is also referred to as “synchronous lighting period”.

  If the synchronization detection function is normal, the synchronization pulse is detected within 90 [msec] which is the least common multiple of the synchronization detection cycle 15 [msec] and the synchronization lighting cycle 18 [msec] from the start of the synchronization lighting. Can do.

  When a synchronous pulse is detected in the synchronous search mode, the synchronous search mode returns to the measurement mode.

  Next, a description will be given of the relationship between the synchronization detection period (here, 15 milliseconds), the lighting time, and the synchronous lighting period when the synchronous lighting is performed separately in the synchronous search mode.

<Division example 1>
As shown in FIG. 29, similarly to the specific example 1 described above, the division example 1 is a case where the lighting time is 3 [msec] and the synchronous lighting cycle is 18 [msec].

  FIG. 30 shows a diagram in which light source drive signals are cut out at the synchronization detection period and overlapped in the case of division example 1. In this case, the synchronization pulse can be detected at any timing within 5 times of synchronous lighting.

  At this time, the synchronization detection cycle 15 [msec] and the lighting cycle 18 [msec] have an asynchronous relationship. The longest time until the synchronization pulse is detected is 90 [msec] which is the least common multiple of the synchronization detection cycle 15 [msec] and the lighting cycle 18 [msec].

<Division example 2>
As shown in FIG. 31, a case where the lighting time is 3 [msec] and the synchronous lighting cycle is 12 [msec] is defined as division example 2.

  FIG. 32 shows a diagram in which, in the case of division example 2, the light source drive signals are cut out and overlapped at the synchronization detection period. In this case, the synchronization pulse can be detected at any timing within 5 times of synchronous lighting.

  At this time, the synchronization detection cycle 15 [msec] and the lighting cycle 12 [msec] are in an asynchronous relationship. The longest time until the synchronization pulse is detected is 60 [msec] which is the least common multiple of the synchronization detection cycle 15 [msec] and the lighting cycle 12 [msec].

<Comparative Example 1>
As shown in FIG. 33, the case of a lighting time of 3 [msec] and a synchronous lighting cycle of 15 [msec] is referred to as Comparative Example 1.

  FIG. 34 shows a diagram in which, in the case of the comparative example 1, the light source drive signal is cut out and overlapped at the synchronization detection period. In this case, the synchronous lighting timing is always in phase with the synchronous detection timing. Therefore, if the timing of synchronous lighting is the same as the timing of the synchronous pulse, the synchronous pulse can be detected, but if the timing of synchronous lighting is different from the timing of the synchronous pulse, the synchronous pulse cannot be detected permanently. .

<Comparative example 2>
As shown in FIG. 35, the case of lighting time 2 [msec] and synchronous lighting cycle 5 [msec] is referred to as Comparative Example 2.

  FIG. 36 shows a diagram in which, in the case of the comparative example 2, the light source drive signals are cut out and overlapped at the synchronization detection period. Also in this case, as in Comparative Example 1, the timing of synchronous lighting is always in phase with the timing of synchronous detection. Therefore, if the timing of synchronous lighting is the same as the timing of the synchronous pulse, the synchronous pulse can be detected, but if the timing of synchronous lighting is different from the timing of the synchronous pulse, the synchronous pulse cannot be detected permanently. .

<Comparative Example 3>
As shown in FIG. 37, the case of lighting time 2 [msec] and synchronous lighting cycle 18 [msec] is referred to as Comparative Example 3.

  FIG. 38 shows a diagram in which, in the case of the comparative example 3, the light source drive signals are cut out and overlapped at the synchronization detection period. In this case, there is a time during which the light source 21 is not turned on within the synchronization detection cycle. When this time is longer than the time required to detect the synchronization pulse, the synchronization pulse cannot be detected depending on the timing.

<Comparative Example 4>
As shown in FIG. 39, the case of lighting time 2 [msec] and synchronous lighting cycle 12 [msec] is referred to as Comparative Example 4.

  FIG. 40 shows a diagram in which, in the case of the comparative example 4, the light source drive signal is cut out and overlapped at the synchronization detection period. In this case, there is a time during which the light source 21 is not turned on within the synchronization detection cycle. When this time is longer than the time required to detect the synchronization pulse, the synchronization pulse cannot be detected depending on the timing.

  Therefore, when performing synchronous lighting separately in the synchronous search mode, the light source driving unit 25 performs synchronous lighting with a period that is different from an integer multiple of the synchronization detection period and a fraction of an integer. Further, the light source driving unit 25 has pw ≧ t / n−T (n) when t> T, where T is the synchronous detection cycle, t is the synchronous lighting cycle, and pw is the lighting time (pulse width) in synchronous lighting. Is the smallest positive integer satisfying T> t−T × n), and when t <T, pw ≧ T−t × n (n is the smallest positive integer satisfying t> T−t × n) The light source 21 is driven so as to satisfy the integer). In this case, it is possible to shorten the lighting time without causing synchronization detection omission.

  FIG. 41 shows an example in which synchronous lighting is performed at a preset number of times until a synchronous pulse is detected in the synchronous search mode, and the measurement mode is restored when the synchronous pulse is detected.

  In FIG. 41, even if a time slightly longer than the synchronization detection period elapses in the second scan, the synchronization pulse is not detected, so the mode is shifted from the measurement mode to the synchronization search mode. In this case, scanning pulse lighting is not performed during the period from the transition to the synchronous search mode to the return to the measurement mode.

  The continuous synchronous lighting is started after an arbitrary time has elapsed from the timing of shifting to the synchronous search mode. If the synchronization detection function is normal, the synchronization pulse is detected within the synchronization detection period 15 [msec] from the start of continuous synchronization lighting.

  However, in the example shown in FIG. 41, the synchronization pulse is not detected even if a time slightly longer than the synchronization detection period has elapsed with respect to the first continuous synchronization lighting after shifting to the synchronization search mode. Therefore, after the light source 21 is turned off for a predetermined time, the second continuous synchronous lighting is performed. Here, the synchronization pulse is not detected even if the time slightly longer than the synchronization detection cycle elapses as in the first continuous synchronized lighting. The third continuous synchronous lighting is started, and a synchronous pulse is detected at a timing when a time shorter than the synchronous detection cycle has elapsed. And it returns to measurement mode from synchronous search mode.

  In this way, the maximum number of times of continuous synchronous lighting (for example, 5 times) is set in advance, and when the synchronization pulse is detected within the number of times, it is determined that the synchronization detection function is operating normally, Return to measurement mode.

  FIG. 42 shows an example of returning to the measurement mode when the synchronization pulse is continuously detected a predetermined number of times in the synchronization search mode. Here, three times are set as the preset number of times.

  In FIG. 42, since a synchronization pulse is not detected even when a time slightly longer than the synchronization detection period elapses in the second scan, the mode shifts from the measurement mode to the synchronization search mode. At this time, scanning pulse lighting is not performed during the period from the transition to the synchronous search mode to the return to the measurement mode.

  The continuous synchronous lighting is started after an arbitrary time after shifting to the synchronous search mode. When the synchronization detection function is operating normally, the synchronization pulse is detected within the synchronization detection period 15 [msec] from the start of continuous synchronization lighting.

  When the first synchronization pulse is detected, similarly, continuous synchronous lighting is started after an arbitrary time. By repeating this, the second and third synchronization pulses are detected.

  When the synchronization pulse is detected three times in succession, it is determined that the synchronization detection function is operating normally, and the measurement mode is restored.

  FIG. 43 shows an example in which no synchronization pulse is detected even if continuous synchronous lighting is performed up to a preset maximum number of times (here, 3 times) in the synchronous search mode.

  In FIG. 43, since a synchronization pulse is not detected even when a time slightly longer than the synchronization detection period has elapsed in the second scan, the mode shifts from the measurement mode to the synchronization search mode. At this time, scanning pulse lighting is not performed during the period from the transition to the synchronous search mode to the return to the measurement mode.

  The continuous synchronous lighting is started after an arbitrary time after shifting to the synchronous search mode. If the synchronization detection function is normal, the synchronization pulse is detected within the synchronization detection period 15 [msec] from the start of continuous synchronization lighting.

  However, in the example shown in FIG. 43, the synchronization pulse is not detected even if continuous synchronous lighting is repeated three times. Therefore, at the timing when the third continuous synchronous lighting ends, it is determined that the synchronization detection function is abnormal, the synchronization search mode is terminated, and a synchronization detection abnormality is output to the object information acquisition unit 203.

  When the light source driving unit 25 outputs the synchronization detection abnormality, the light source 21 is not turned on unless the synchronization detection abnormality is cleared from the object information acquisition unit 203.

  As an example, as shown in FIG. 44, in the first scan after returning to the measurement mode, the scanning pulse is not turned on, only the synchronous lighting is performed, and from the synchronization pulse detected in the synchronous search mode to the next synchronization pulse. It may be confirmed whether or not the time matches the synchronization detection cycle. When a synchronization pulse is detected in the measurement mode, it is determined that the synchronization detection cycle is correct. Here, it is determined that the synchronization detection period is correct if adjacent synchronization pulses can be detected, but the determination may be made by measuring the detection time interval of the synchronization pulses using an internal counter.

  In the measurement mode, when it is determined that the synchronization detection cycle is correct, the scanning pulse is lit based on the detection timing of the synchronization pulse.

  Further, the number of times of returning from the synchronous search mode to the measurement mode may be recorded and notified to the user. As a notification method to the user, displaying on the screen of the display device 30, storing in the memory 50, saving in a measurement log file, and the like can be considered. By confirming the result, the user can confirm the stability of the operation and the measurement data before and after the synchronization pulse is not detected.

  In addition, if the falling edge cannot be detected in the polygon lock signal from the optical deflector 32, the light source 21 is turned off because the pulse cannot be emitted at the target accurate measurement position.

  FIG. 45 shows an example of measurement data transfer and invalid data transfer information. Here, data transfer is performed in the synchronous search mode as in the measurement mode. Data transfer is triggered by the timing of shifting to the synchronous search mode and lighting in the light source drive signal. As the data transfer in the synchronous search mode, a method of transferring invalid data prepared in advance or a method of adding invalid data transfer information to measurement data immediately before shifting to the synchronous search mode can be considered. The synchronous lighting period in the synchronous search mode needs to be set to a period at which data transfer can be sufficiently performed.

  By transferring invalid data in the synchronous search mode, it is possible to operate in the same sequence as during measurement, so that the control program and control software can be shared and the development man-hours can be reduced.

  In addition, the measurement data acquired in the scan immediately before the transition to the synchronous search mode is not detected because the sync pulse is not detected. There is no reliability. Therefore, the measurement data acquired by the scanning is not updated and is not used as measurement data.

  Further, the synchronous lighting cycle and lighting time can be changed (see FIG. 46). Thereby, it is possible to easily cope with various design conditions. Further, it is possible to easily cope with the rotational speed and rotational fluctuation of the rotating mirror.

  The object information acquisition unit 203 obtains object information such as the position of the object, the size of the object, and the shape of the object, and stores them in the memory 50.

  Further, the object information acquisition unit 203 determines that an object has not been detected if a detection pulse cannot be detected from the detection signal even after a predetermined time has elapsed since the light source 21 was turned on. The determination result is stored in the memory 50.

  Returning to FIG. 2, the monitoring control device 40 refers to the memory 50 at every predetermined timing, and moves the object when there is an object in front of the vehicle 1 based on the object information stored in the memory 50. The movement information including the moving direction and the moving speed is obtained when the object is moving. Then, the object information and the movement information are displayed on the display device 30.

  Further, the monitoring control device 40 determines the presence or absence of danger based on the object information and the movement information, and if it is determined that there is danger, notifies the main controller and the sound / alarm generating device 60 of the vehicle 1.

  As shown in FIG. 47 as an example, the voice / alarm generator 60 includes a voice synthesizer 61, an alarm signal generator 62, a speaker 63, and the like.

  The voice synthesizer 61 has a plurality of pieces of voice data. When the information indicating that there is a danger is received from the monitoring controller 40, the voice synthesizer 61 selects the corresponding voice data and outputs it to the speaker 63.

  When the warning signal generation device 62 receives information indicating that there is danger from the monitoring control device 40, the warning signal generation device 62 generates a corresponding warning signal and outputs it to the speaker 63.

  The main controller of the vehicle 1 controls the traveling of the vehicle 1 based on information from the monitoring device 10.

  As is clear from the above description, in the present embodiment, the photodetector in the optical scanning device of the present invention is configured by the synchronization detection photodetector 24, and the light source driving device is configured by the light source driving unit 25. The light detection system 202 constitutes a light receiving means in the object detection apparatus of the present invention.

  As described above, the optical scanning device 200 according to the present embodiment includes the light emission system 201, the light deflection system 204, and the like. The light emission system 201 includes a light source 21, a coupling lens 22, a synchronization lens 23, a synchronization detection photodetector 24, a light source drive unit 25, a synchronization signal generation unit 26, and the like. The optical deflection system 204 includes a reflection mirror 31, an optical deflector 32, and the like.

  The light source driving unit 25 drives the light source 21 by the first driving method and the second driving method having a light emission pattern different from that of the first driving method outside the scanning region, and the first driving method in the scanning region. The light source 21 is driven by a third driving method that is different from the method and the second driving method.

  The first driving method is a light emission pattern synchronized with a period (synchronization detection period) in which the synchronization detection photodetector 24 is scanned, and the second drive method detects light reception of the synchronization detection photodetector 24. It is a light emission pattern that is specialized for doing this.

  In the synchronous search mode, the second drive method is selected, and in the measurement mode, the first drive method and the third drive method are selected. Further, the amount of emitted light in the third driving method is larger than the amount of emitted light in the first driving method and the emitted light amount in the second driving method.

  In this case, synchronization with the rotating mirror can be detected without using a rotary encoder for detecting the angular position of the rotating mirror in the rotating direction. That is, since the rotary encoder is unnecessary, the apparatus can be reduced in size, particularly reduced in thickness. Further, the light for synchronization detection and the light for object detection can be controlled using the same light source.

  In addition, when the synchronization timing is not known, such as when the synchronization is temporarily lost at the time of start-up and when the synchronization is temporarily lost, the driving method for detecting the synchronization pulse (second driving method) is switched to detect the synchronization pulse, and the device Without stopping, it is possible to return to the measurement mode after detecting the synchronization pulse. At this time, the amount of light emitted from the light source can be switched in conjunction with the first driving method.

  Furthermore, since the driving method for synchronization detection is switched between when the synchronization timing is not known, such as when starting and when synchronization is lost, and when the synchronization timing is known, such as when detecting an object, the light source 21 is switched. It is possible to detect synchronously while keeping the lighting time of.

  Therefore, according to the optical scanning device 200 according to the present embodiment, it is possible to reduce the size, extend the life, and reduce the power consumption.

  The laser radar 20 according to the present embodiment includes the optical scanning device 200. As a result, it is possible to reduce the size, extend the lifetime, and reduce the power consumption.

  And according to the monitoring apparatus 10 which concerns on this embodiment, since the laser radar 20 is provided, size reduction, long life, and low power consumption can be achieved.

  And according to the vehicle 1 which concerns on this embodiment, since the size reduction, long life, and low power consumption of the monitoring apparatus 10 are achieved, the freedom degree of the installation position of the monitoring apparatus 10 can be improved. Safe driving can be performed stably.

  In the above embodiment, the optical deflector 32 may have a rotating polygon mirror instead of the rotating mirror.

  Moreover, although the said embodiment demonstrated the case where the light emission system 201 was arrange | positioned at the + Z side of the photon detection system 202, it is not limited to this.

  In the above embodiment, the monitoring control device 40 may perform a part of the processing in the object information acquisition unit 203, or the object information acquisition unit 203 may perform a part of the processing in the monitoring control device 40. good.

  In the above embodiment, the object information acquisition unit 203 may perform a part of the processing in the light source driving unit 25, or the light source driving unit 25 may perform a part of the processing in the object information acquisition unit 203. good.

  Moreover, although the said embodiment demonstrated the case where the monitoring apparatus 10 was provided with one laser radar 20, it is not limited to this. A plurality of laser radars 20 may be provided according to the size of the vehicle, the monitoring area, and the like.

  Moreover, although the said embodiment demonstrated the case where the laser radar 20 was used for the monitoring apparatus 10 which monitors the advancing direction of a vehicle, it is not limited to this. For example, you may use for the apparatus which monitors the back and side surface of a vehicle.

  Furthermore, the laser radar 20 can also be used for sensing devices other than those for in-vehicle use. In this case, the monitoring control device 40 outputs alarm information according to the purpose of sensing.

  The laser radar 20 can also be used for detecting only the presence or absence of an object.

  The laser radar 20 can also be used for applications other than the sensing device (for example, a distance measuring device or a shape measuring device).

  The optical scanning device 200 can also be used for applications other than the object detection device (for example, an image display device or an image forming device).

  DESCRIPTION OF SYMBOLS 1 ... Vehicle (traveling body), 10 ... Monitoring apparatus (sensing apparatus), 20 ... Laser radar (object detection apparatus), 21 ... Light source, 22 ... Coupling lens, 23 ... Synchronous lens, 24 ... Photodetector for synchronous detection (Light detector), 25 ... light source drive unit (light source drive device), 26 ... synchronization signal generation unit, 31 ... reflection mirror, 32 ... light deflector, 40 ... monitoring control device, 41 ... imaging optical system, 42 ... Light receiver, 43 ... detection signal generation unit, 50 ... memory, 60 ... sound / alarm generation device, 200 ... light scanning device, 201 ... light emission system, 202 ... light detection system (light receiving means), 203 ... object information acquisition unit 204, an optical deflection system.

Japanese Patent No. 5251858 Japanese Patent No. 5598831 Japanese Patent No. 5617554 Japanese Patent No. 5082704 Japanese Patent No. 5660429 Japanese Patent No. 4673078

Claims (17)

An optical scanning device that scans a predetermined scanning region with light,
A light source;
A light source driving device for driving the light source;
An optical deflector for deflecting light from the light source;
A photodetector for determining timing for starting scanning of the scanning region,
The light detector and the scanning region are sequentially scanned by one scan by the light deflector,
The light source driving device drives the light source by a second driving method having a light emission pattern different from that of the first driving method and the first driving method outside the scanning region. An optical scanning device that drives the light source by a third driving method that is different from the first driving method and the second driving method. The first driving method is a light emission pattern synchronized with a period in which the photodetector is scanned, and the second driving method is a light emission pattern specialized for detecting light reception of the photodetector. Yes,
2. The optical scanning device according to claim 1, wherein the light source driving device switches from the first driving method to the second driving method when light reception of the photodetector is not detected. 3.   3. The optical scanning device according to claim 1, wherein the light source driving device switches to the first driving method when detecting light reception of the photodetector in the second driving method. 4.   3. The light according to claim 1, wherein the light source driving device switches to the first driving method when detecting light reception by the photodetector for a preset number of times in the second driving method. 4. Scanning device.   When the light source driving device is switched from the second driving method to the first driving method, the light source driving device detects light reception of the photodetector by the first driving method, and then the light source by the third driving method. The optical scanning device according to claim 3, wherein the optical scanning device is driven.   2. The light source driving device according to claim 1, wherein, in the second driving method, the light source is pulse-lit at a cycle that is different from an integer multiple and a fraction of an integer of the scanning cycle of the photodetector. The optical scanning apparatus as described in any one of -5.   In the second driving method, when the scanning cycle is T, the pulse lighting cycle is t, and the pulse width of the pulse lighting is pw, when t> T, pw ≧ t / n−T (n is , T> t−T × n), and when t <T, pw ≧ T−t × n (n is the smallest positive integer satisfying t> T−t × n) The optical scanning device according to claim 6, wherein an integer) is satisfied.   8. The optical scanning device according to claim 6, wherein in the second driving method, a maximum number of times that the light source is pulse-lit before detection of light reception by the photodetector is set. 9.   In the second driving method, the longest time for detecting light received by the photodetector is set longer than the time of the pulse lighting cycle and the least common multiple of the scanning cycle of the photodetector. The optical scanning device according to claim 6, wherein the optical scanning device is provided.   10. The optical scanning device according to claim 6, wherein the light source driving device is capable of changing a pulse lighting cycle and a pulse lighting time in the second driving method. 11.   11. The light source driving device according to claim 6, wherein in the second driving method, invalid data different from measurement data is transferred using a pulse lighting timing as a scanning start timing for the scanning region. The optical scanning device according to Item.   12. The light source driving device according to claim 1, wherein, in the second driving method, when light reception of the photodetector is not detected, the light source driving device stops driving the light source and notifies an abnormality. The optical scanning device according to one item.   The light source driving device does not update measurement data acquired by the third driving method in the immediately preceding scan when light reception by the photodetector is not detected in the first driving method. Item 13. The optical scanning device according to any one of Items 1 to 12.   The light emission amount of the light source when driven by the first drive method and the second drive method is smaller than the light emission amount of the light source when driven by the third drive method. Item 14. The optical scanning device according to any one of Items 1 to 13. An optical scanning device according to any one of claims 1 to 14,
An object detection device comprising: a light receiving unit configured to receive light emitted from the optical scanning device toward a scanning region and reflected by the object when the object is in the scanning region. The object detection device according to claim 15;
And a monitoring control device that obtains at least one of the presence / absence of the object, the position of the object, and the moving speed of the object based on the output of the object detection device. A sensing device according to claim 16;
A traveling body comprising: a control device that controls traveling based on information from the sensing device.

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