Laser imaging detection and ranging device

Abstract

The present invention relates to a laser imaging detection and ranging device, which includes a light source (12), a mirror (16), a rotatable shaft (24), and a motor (26). The light source (12) is configured to emit a beam for scanning a scanning area (SZ) having a predetermined beam width; the rotatable shaft (24) has a central axis (CX) parallel to the reflecting surface (16a) of the mirror (16) and the rotatable shaft (24) is connected to the back surface (16b) of the mirror (16). The motor (26) is configured to rotate the shaft (24) to rotate the mirror (16) between a first position and a second position. The light source (12) and the mirror (16) are arranged in a positional relationship such that when the mirror (16) is in the first position, the mirror center (MC) is aligned with the beam center (BC), and when the mirror (16) swings between the first position (excluding the first position) and the second position (including the second position), the mirror center (MC) is displaced within the movement area.

Description

Technical Field

[0001] The present disclosure relates to a LIDAR device for calculating the distance to an object. Background Art

[0002] LIDAR, which stands for Light Detection and Ranging, is a remote sensing method for measuring the distance to an object in a scanned area. Such LIDAR systems have been well used in various fields, including those for autonomous driving areas. A LIDAR system typically uses a light emitter, a light receiver, and a mirror for reflecting the emitted light towards the scanned area. A scanning mirror is usually used by rotating the mirror to expand the detection area. Summary of the Invention

[0003] One aspect of the present disclosure is a LIDAR device for measuring the distance to an object in a predetermined scanned area. The device includes a light source, a mirror, a rotatable shaft, and a motor. The light source is configured to emit a beam for scanning the scanned area with a predetermined beam width. The mirror has a reflective surface and a back surface opposite to the reflective surface. The mirror is configured to reflect the beam emitted from the light source towards the scanned area using the reflective surface. The rotatable shaft has a central axis parallel to the reflective surface of the mirror. The shaft is connected to the back surface of the mirror via, for example, a connecting member.

[0004] The motor is configured to rotate the shaft to swing the mirror between a first position corresponding to one end of the predetermined scanned area and a second position corresponding to the other end of the predetermined scanned area, and the incident angle of the beam with respect to the reflective surface is greater when the mirror is in the first position than when the mirror is in the second position.

[0005] When the center of the beam is defined as the center of the beam width of the beam from the light source to the reflective surface, then one side of the center axis of the shaft including the center of the beam is defined as the movement area.

[0006] The light source and the mirror are arranged in a positional relationship such that when viewed in the direction of the central axis of the shaft, when the mirror is in the first position, the center of the mirror is aligned with the center of the beam, the center of the mirror being defined as the point on the reflective surface closest to the central axis of the shaft, and when the mirror swings between the first position (excluding the first position) and the second position (including the second position), the center of the mirror is displaced within the movement area. Brief Description of the Drawings

[0007] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings.

[0008] Figure 1 is a schematic diagram of a LIDAR device according to a first embodiment.

[0009] Figure 2 It is a top view showing the positional relationship between the light-emitting module and the scanning mirror.

[0010] Figure 3 It is a side view of the LIDAR device.

[0011] Figure 4 It is a diagram showing that the scanning mirror reflects the laser beam at -60 degrees in (a), 0 degrees in (b), and +60 degrees in (c).

[0012] Figure 5 It is a block diagram of the LIDAR device.

[0013] Figure 6 It is a timing diagram of the detection signal, emission control signal, and return signal according to the first embodiment.

[0014] Figure 7 It is a flowchart executed by the LIDAR device according to the first embodiment.

[0015] Figure 8 It is a schematic diagram showing a comparative example of the positional relationship between the light-emitting module and the scanning mirror.

[0016] Figure 9 It is a timing diagram of a comparative example of the detection signal, emission control signal, and return signal.

[0017] Figure 10 It is a timing diagram of the detection signal, emission control signal, and return signal according to the second embodiment.

[0018] Figure 11 It is a flowchart executed by the LIDAR device according to the second embodiment.

[0019] Figure 12 It is a timing diagram of the detection signal, emission control signal, and return signal according to the third embodiment.

[0020] Figure 13 It is a flowchart executed by the LIDAR device according to the third embodiment.

[0021] Figure 14 It is a timing diagram of the detection signal, emission control signal, and return signal according to the fourth embodiment.

[0022] Figure 15 It is a flowchart executed by the LIDAR device according to the fourth embodiment.

[0023] Figure 16 It is a block diagram of the LIDAR device according to the fifth embodiment.

[0024] Figure 17 It is a timing chart of a detection signal, a transmission control signal, and a return signal according to the fifth embodiment.

[0025] Figure 18 It is a flowchart executed by the LIDAR device according to the fifth embodiment. Detailed Embodiments

[0026] Hereinafter, multiple embodiments of the present disclosure will be described with reference to the drawings. In the following embodiments, the same or equivalent components are denoted by the same reference numerals, and descriptions will be provided for the same reference numerals to simplify the description. Further, in the following embodiments, although the light detection and ranging (LIDAR) device is installed in a vehicle such as a motor vehicle, the LIDAR device 10 can be installed in any vehicle such as a motorcycle, an airplane, a ship, a drone, etc.

[0027] (First Embodiment)

[0028] Figures 1 to 3 A schematic diagram of the LIDAR device 10 according to the first embodiment is shown. The LIDAR device 10 is configured to calculate the distance to an object X in the scanning area SZ using the time-of-flight (ToF) technique. The LIDAR device 10 basically includes a light emitting module 12, a light receiving module 14, a scanner module 18, and a motor controller 50 (see Figure 5 ). The calculation of the distance to the object X is performed by a controller 21 integrally provided in the light receiving module 14, as will be described later.

[0029] The LIDAR device 10 is formed as a single component housed in a box-like container 10a, as Figure 1 shown. In this embodiment, the vertical surface is defined as the surface along which the optical axis of the light emitting module 12 extends and which is parallel to the central axis CX of the rotatable shaft 24 (described later), and the vertical direction is defined as the direction parallel to the central axis CX, as Figure 1 defined. Then, the light emitting module 12 and the light receiving module 14 are arranged in the direction along the vertical direction as Figure 1 defined. Figure 1 The vertical direction defined in Figure 1 can match the up-and-down direction of the vehicle on which the LIDAR device 10 is installed. In other words, the light emitting module 12 and the light receiving module 14 are arranged in the direction along the rotatable shaft 24 of the scanner module 18. More specifically, the light emitting module 12 is provided above the light receiving module 14, as

[0030] The light emitting module 12 or the light source is configured to emit a laser beam toward the scanning mirror 16 of the scanner module 18. As Figure 1 and Figure 2 shown, the light emitting module 12 includes two pairs of light emitters 20a, 20b and transmitter lenses 22a, 22b. Each of the light emitters 20a, 20b is, for example, a semiconductor laser diode configured to emit pulsed laser light. Each of the light emitters 20a, 20b is electrically connected to the controller 21 and is configured to emit a laser beam when the light emitting module 12 receives an emission control signal from the controller 21. Therefore, the emission timing of the light emitters 20a, 20b can be controlled by the emission control signal output from the controller 21.

[0031] The light emitting module 12 is also configured to output the actual emission timing to the controller 21. The actual emission timing is the timing at which the light emitting module 12 actually emits a light beam. As will be described below, the actual emission timing is used to compensate for errors generated when the controller 21 calculates the distance.

[0032] Each of the transmitter lenses 22a, 22b is a lens configured to focus the pulsed laser light emitted from the light emitter to form a vertical line (i.e., a linear light beam) extending in the direction along the vertical direction (see Figure 1 ). That is, the LIDAR device 10 employs a one-dimensional line scanning method that uses a linear laser beam extending in the vertical direction for horizontal scanning.

[0033] In this embodiment, the horizontal surface is defined as a surface perpendicular to the vertical surface, and the horizontal direction is along the horizontal surface defined as in Figure 1 . Therefore, the two pairs of light emitters 20a, 20b and the transmitter lenses 22a, 22b are arranged in the horizontal direction. That is, the horizontal direction is a direction perpendicular to the laser emission direction. Hereinafter, the laser beam emitted from one of the two pairs of light emitters and transmitter lenses ( Figure 2 the left pair 20a, 22a in ) is referred to as the first laser beam, and the laser beam emitted from the other of the two pairs of light emitters and transmitter lenses ( Figure 2 the right pair 20b, 22b in ) is referred to as the second laser beam. Therefore, the first laser beam and the second laser beam emitted from the two light emitters 20a, 20b and focused by the transmitter lenses 22a, 22b are collectively referred to as the light beam band LB.

[0034] As Figure 2As shown, the light beam bands LB of the two light emitters 20a and 20b have a beam width W, which is the width in a direction perpendicular to the light propagation direction when viewed from above. Therefore, the beam center BC is defined as the center of the beam width W of the light beam band LB. More specifically, the beam center BC is a center line extending along the center point of the beam width W in a direction perpendicular to the light propagation direction when viewed from above.

[0035] As Figure 3 shown, the scanner module 18 includes a scanning mirror 16, a rotatable shaft 24, a drive motor 26, and an angle sensor 28. The rotatable shaft 24 is a shaft configured to rotate about a central axis CX. In this embodiment, the central axis CX extends in a direction parallel to the vertical direction defined as Figure 1 . The rotatable shaft 24 has a columnar shape with a specified diameter. The side surface 24a of the rotatable shaft 24 is connected to the scanning mirror 16 via, for example, a connecting member. It should be noted that Figures 1 to 3 the connecting member is not shown therein.

[0036] The scanning mirror 16 is a mirror configured to directly or indirectly reflect a laser beam toward the scanning area SZ through one or more other mirrors. In addition, the scanning mirror 16 in this embodiment is configured to reflect a return beam reflected by the object X toward the light receiving module 14. That is, the scanning mirror 16 serves as both a transmitter mirror and a receiver mirror.

[0037] In this embodiment, the scanning mirror 16 is a plate-like member and includes a reflection surface 16a and a back surface 16b opposite to the reflection surface 16a. The back surface 16b of the scanning mirror 16 is connected to the side surface of the rotatable shaft 24 via, for example, a connecting member. Therefore, as Figure 2 shown, the reflection surface 16a is separated from the central axis CX of the rotatable shaft 24 by a predetermined distance (for example, the radius of the rotatable shaft 24 + the thickness of the mirror + the thickness of the connecting member). Thus, the scanning mirror 16 rotates (i.e., swings) around the central axis CX, rather than rotates (i.e., swings) about the central axis CX.

[0038] In this embodiment, when viewed from the front side, the reflection surface 16a has a quadrilateral shape (e.g., a rectangular shape) (see Figure 5 ). However, the shape of the reflection surface 16a does not have to be limited to a rectangular shape and can be a trapezoidal shape having a lower base and an upper base located above the lower base in the vertical direction. Alternatively, the shape of the reflection surface 16a can be a shape formed by chamfering the corners in a rectangular shape. The reflection surface 16a extends in the vertical direction. Refer to Figure 5, two edge portions 30 of the reflective surface 16a are defined as portions including the elongated side edges of the reflective surface 16a that extend in a direction along the vertical direction. Similarly, the central portion 32 of the reflective surface 16a is defined as the portion of the central region of the reflective surface 16a between the two edge portions 30. Then, the mirror center MC is defined as the point on the reflective surface 16a that is closest to the central axis CX of the rotatable shaft 24 when viewed in the direction along the central axis CX, i.e., the vertical direction, as Figure 2 shown. In this embodiment, the mirror center MC is the center point between the two edge portions 30 when viewed in the direction along the central axis CX. In other words, the mirror center MC is the center point of the width of the reflective surface 16a.

[0039] The drive motor 26 is an electric motor configured to rotate the rotatable shaft 24 about the central axis CX. The drive motor 26 is electrically connected to the motor controller 50, and the operation of the drive motor 26 is controlled by a motor drive signal output from the motor controller 50. The motor controller 50 is an electronic control unit (ECU) including, for example, at least one processor and a memory. The memory includes random access memory, read-only memory, flash memory, or a combination thereof. The memory has instructions stored thereon that, when executed by the processor, cause the processor to control the drive motor 26.

[0040] The motor controller 50 is configured to control the drive motor 26 to operate alternately in opposite directions. Therefore, the rotatable shaft 24 rotates backward and forward (i.e., in two directions) by the motor, so that the scanning mirror 16 swings between a first position and a second position within a predetermined scanning angle range. That is, the scanning mirror 16 swings periodically between the first position and the second position.

[0041] As Figure 2 shown, the first position of the scanning mirror 16 is the position corresponding to one end A of the scanning area SZ, and the second position of the scanning mirror 16 is the position corresponding to the other end B of the scanning area SZ. As Figure 4 shown, the incident angle of the light beam with respect to the reflective surface 16a when the mirror is in the first position is greater than the incident angle of the light beam with respect to the reflective surface 16a when the mirror 16 is in the second position. In this embodiment, the scanning angle range is set to 120 degrees (i.e., -60° ≤ scanning angle θ ≤ +60°), and the scanning angle θ is -60° when the scanning mirror 16 is in the first position, and the scanning angle θ is +60° when the scanning mirror 16 is in the second position (see Figure 4 ).

[0042] Referring to Figure 2 , the movement region is defined as the side of the beam center BC including the central axis CX of the shaft 24 when viewed in the direction along the central axis CX ( Figure 2the shaded area in). Then, the light emitting module 12 and the scanning mirror 16 are arranged to have the following positional relationship, which makes the mirror center MC aligned with the beam center BC when the mirror is in the first position when viewed in the direction of the central axis CX of the rotatable shaft 24 (see Figure 2 and Figure 4 (a) in). On the other hand, when the mirror 16 swings between the first position (excluding the first position) and the second position (including the second position), the mirror center MC is displaced within the movement area (see Figure 4 (b) and (c) in). In other words, except when the scanning mirror 16 reaches the first position, the mirror center MC of the scanning mirror 16 is displaced within the movement area. Therefore, except when the scanning mirror 16 is in the first position, the mirror center MC and the beam center BC are offset from each other.

[0043] As Figure 4 (a) in shows, when the scanning mirror 16 is in the first position, the first laser beam emitted from the left light emitter is reflected at the left edge portion 30 of the reflection surface 16a, and the second laser beam emitted from the right light emitter is reflected at the right edge portion 30 of the reflection surface 16a (however, a part of the first laser beam and a part of the second laser beam may be reflected at the central portion 32). On the other hand, as Figure 4 (c) in shows, when the scanning mirror 16 is in the second position, the first laser beam and the second laser beam emitted from the two light emitters are mainly reflected at the central portion 32 of the reflection surface 16a. Therefore, compared with when the mirror 16 is in the first position, the amount of the beam reflected by the pair of edge portions 30 is reduced when the mirror 16 is in the second position.

[0044] The scanner module 18 also includes an angle sensor 28 that detects the rotation angle of the scanning mirror 16. The angle sensor 28 can be an optical sensor, a mechanical sensor, an ultrasonic sensor, etc. The angle sensor 28 is configured to detect the rotation angle at a plurality of predetermined angular intervals during each rotation cycle of the scanning mirror 16 between the first position and the second position. In this embodiment, the angle sensor 28 is configured to detect the rotation angle of the mirror 16 every 0.1 degree (i.e., the maximum angular resolution is 0.1 degree). However, the resolution of the angle sensor 28 does not have to be limited to 0.1 degree, and can be, for example, 0.05 degree or 0.2 degree.

[0045] The angle sensor 28 is connected to the controller 21 and is configured to output a detection signal indicating the rotation angle of the mirror at angular intervals (i.e., at 0.1-degree intervals). The inventors of the present disclosure have found that, since the movable scanning mirror 16 moves to swing between the first position and the second position, an acceleration is applied to the scanning mirror 16 during the swing. Therefore, the rotational speed of the scanning mirror 16 changes (does not remain constant) during one rotation period of the scanning mirror 16. Accordingly, the rotation angle of the scanning mirror 16 is not counted by the angle sensor 28 at the same time intervals, as Figure 6 shown. That is, the angle sensor 28 outputs detection signals to the controller 21 at the same angular intervals but at different time intervals.

[0046] The light receiving module 14 includes a photoreceiver 34 and a controller 21. The photoreceiver 34 includes an integrated circuit 36 having a receiving lens 35 and a plurality of photosensitive devices, and the controller 21 is provided within the integrated circuit 36 of the photoreceiver 34. In other words, in this embodiment, the photoreceiver 34 and the controller 21 are integrally formed as a single module. In this embodiment, the plurality of photosensitive devices of the photoreceiver 34 are single-photon avalanche diodes (SPADs) 38, which are formed as a two-dimensional SPAD array 34a by arranging a plurality of SPADs 38 in both columns and rows. Since the SPAD array 34a constitutes a digital circuit, the SPAD array 34a has a high angular resolution compared to other photosensitive devices forming an analog-type circuit. Accordingly, the photoreceiver 34 can detect the return beam at small rotation angle intervals, for example, at 0.1-degree intervals. When the photoreceiver 34 (SPAD array 34a) receives the return beam, the photoreceiver 34 outputs a return signal as a digital signal to the controller 21 according to the return beam reflected by the object X. The photoreceiver 34 further includes a decoder 37 configured such that the SPADs 38 in a column can receive the return beam. It should be noted that the photoreceiver 34 may include photosensitive elements other than the plurality of SPADs. For example, a conventional type of avalanche photodiode or another photodiode may be used as the photosensitive element.

[0047] In this embodiment, the controller 21 is configured to control the emission of the laser beam by controlling the light emitting module 12. The controller 21 is further configured to calculate the distance to the object X based on the difference between the light emission timing of the laser beam emitted by the light emitting module 12 and the light reception timing of the return beam received by the light receiving module 14, as will be described below. Since the controller 21 is implemented together with the photoreceiver 34 (SPAD array 34a) on the integrated circuit 36 as a digital circuit, the controller 21 can perform the above-mentioned functions without a programmable processor.

[0048] Figure 5 Functional blocks of the controller 21 are shown. Although Figure 5It is shown that the controller 21 has these functions, but one or some of the functions can be performed by one or more physically separated circuits. The controller 21 includes a transmission control unit 39 and a calculation unit 40 as functional blocks.

[0049] The transmission control unit 39 is configured to control the light-emitting module 12 by outputting a transmission control signal to the light-emitting module 12. In this embodiment, the transmission control unit 39 is configured to output a transmission control signal when receiving a detection signal from the angle sensor 28 (see Figure 6 ). Thus, whenever the angle sensor 28 detects the rotation angle of the scanning mirror 16, the light-emitting module 12 emits a laser beam. In other words, the light-emitting module 12 emits laser beams at the same interval as the angular interval (i.e., 0.1-degree interval). In addition, the transmission control unit 39 is configured to output a signal output timing to the calculation unit 40. The signal output timing is the timing when the transmission control unit 39 outputs a control signal to the light-emitting module 12.

[0050] The calculation unit 40 is configured to calculate the distance to the object X using the return signal from the light-receiving module 14 and the signal output timing from the transmission control unit 39. More specifically, the calculation unit 40 uses the time-of-flight principle to calculate the distance to the object X based on the difference between the signal output timing and the light-receiving timing (i.e., the return signal). In addition, the calculation unit 40 is configured to receive the above-mentioned actual emission timing from the light-emitting module 12 (see Figure 5 ). Then, the calculation unit 40 is configured to correct the calculated distance using the actual emission timing. That is, there is a time lag from when the controller 21 outputs the signal output timing until the light-emitting module 12 actually emits a laser beam. Therefore, the controller 21 corrects the calculated distance based on the signal output timing using the actual emission timing. Alternatively, the calculation unit 40 can calculate the distance to the object X using the time difference between the actual emission timing and the timing of receiving the return signal.

[0051] Figure 7 A flowchart executed by the LIDAR device 10 to calculate the distance to the object X is shown. At step S10, when the angle sensor 28 detects the rotation angle of the scanning mirror 16 at each predetermined angle, at step S20, the angle sensor 28 outputs a detection signal indicating the detected rotation angle to the controller 21 (transmission control unit 39). As described above, the angle sensor 28 detects the rotation angle at a predetermined rotation angle interval (e.g., 0.1-degree interval), but the rotation speed of the scanning mirror 16 varies between the first position and the second position. At step S30, when the controller 21 receives the detection signal from the angle sensor 28, the controller 21 outputs a transmission control signal to the light-emitting module 12.

[0052] At step S40, when the light-emitting module 12 receives the emission control signal, the light-emitting module 12 emits a laser beam toward the scanning mirror 16. At step S50, the light-emitting module 12 also outputs the actual emission timing as the timing at which the light-emitting module 12 actually emits the laser beam to the controller 21 (computing unit 40).

[0053] The emitted laser beam is reflected at the reflecting surface 16a of the scanning mirror 16 and travels to the scanning area SZ. Then, if the laser beam is reflected by the object X, the return signal returns to the LIDAR device 10 and is again reflected by the reflecting surface 16a of the scanning mirror 16 toward the light-receiving module 14. At step S60, when the return beam reaches the light-receiving module 14, the light-receiving module 14 (SPAD array) detects the return beam, and then at step S70, the light-receiving module 14 outputs a return signal to the controller 21 (computing unit 40) in response to receiving the return beam.

[0054] At step S80, the controller 21 (computing unit 40) calculates the distance to the object X using the signal output timing and the return signal. Then, at step S90, the controller 21 (computing unit 40) corrects the calculated distance using the actual emission timing.

[0055] As described above, the LIDAR device 10 according to the first embodiment includes a light-emitting module 12 and a scanning mirror 16, and the light-emitting module 12 and the scanning mirror 16 are arranged to have a positional relationship such that when viewed in the direction of the central axis CX of the rotatable shaft 24, the mirror center MC is aligned with the beam center BC when the mirror 16 is in the first position. The first position is defined as the position corresponding to one end A of the scanning area SZ, and when the scanning mirror 16 is in the first position, the incident angle of the beam with respect to the reflecting surface 16a has the maximum value in the scanning angle range. On the other hand, when the mirror 16 swings between the first position (excluding the first position) and the second position (including the second position), the mirror center MC is displaced within the movement area. The second position is defined as the position corresponding to the other end B of the scanning area SZ, and when the scanning mirror 16 is in the second position, the incident angle of the beam with respect to the reflecting surface 16a has the minimum value in the scanning angle range.

[0056] Therefore, since the beam center BC is aligned with the mirror center MC when the scanning mirror 16 is in the first position, the first beam and the second beam are mainly reflected at the edge portion 30 where the mirror center MC of the reflecting surface 16a is located between them. More specifically, as Figure 4As shown in (a) thereof, when the scanning mirror 16 is in the first position, the first light beam and the second light beam are mainly reflected at the left edge portion and the right edge portion of the reflecting surface 16a, respectively. Therefore, as long as the reflecting surface 16a can receive the first light beam and the second light beam at the two edge portions 30 when the mirror 16 is in the first position, the width of the reflecting surface 16a (scanning mirror 16) can be minimized. As a result, since the mirror 16 has the minimum width, the size of the LIDAR device 10 can be reduced.

[0057] Conversely, as Figure 8 shown, if the light emitting module 12 and the scanning mirror 16 are arranged such that the mirror center MC is aligned with the central axis CX, at least the left side of the reflecting surface 16a needs to be extended when the scanning mirror 16 is in the first position in order to capture the first laser beam. As a result, since the mirror 16 has an extended width, the size of the LIDAR device 10 will increase.

[0058] In this embodiment, the angle sensor 28 is configured to: detect the rotation angle of the scanning mirror 16; and output a detection signal at a plurality of predetermined angular intervals (0.1 degree intervals in this embodiment) during each rotation cycle between the first position and the second position of the scanning mirror 16. Then, when the controller 21 receives the detection signal from the angle sensor 28, it outputs a control signal to the light emitting module 12, as Figure 6 shown. Therefore, the light emitting module 12 can emit laser beams at the same intervals as the plurality of predetermined angular intervals.

[0059] Here, Figure 9 a comparative example is shown in which the light emitting module 12 is controlled to emit laser beams at a plurality of predetermined "time" intervals (for example, every 27.8 microseconds). Since the scanning mirror 16 swings between the first position and the second position, the rotation speed irregularly changes due to the acceleration applied to the mirror 16. Therefore, although the light emitting module 12 can emit laser beams at a predetermined "time" interval, the light emitting module 12 cannot emit laser beams at a plurality of predetermined "rotation angle" intervals between the first position and the second position. Therefore, the amount of laser beams for each area corresponding to each rotation angle interval in the scanning area SZ will vary.

[0060] Conversely, since in this embodiment the light emitting module 12 is controlled to emit laser beams based on the rotation angle of the scanning mirror 16 detected by the angle sensor 28, rather than based on a time interval, the LIDAR device 10 can emit laser beams uniformly for each rotation angle interval. Therefore, the LIDAR device 10 can scan the scanning area SZ evenly.

[0061] The optical receiving module 14 includes an integrated circuit 36 on which the controller 21 is implemented. That is, in this embodiment, the controller 21 is integrally formed with the optical receiver 34 (SPAD array 34a), and the distance between the controller 21 and the optical receiver 34 can be reduced compared to the case where the controller 21 and the optical receiver 34 are physically separated. Therefore, the time required to transmit the return signal from the optical receiver 34 to the controller 21 can be reduced, and thus the accuracy of the calculated distance can be improved.

[0062] The optical receiving module 14 includes a plurality of SPADs 38 as photosensitive devices. The SPADs 38 have the sensitivity to receive the return light beam at high-resolution time intervals. Therefore, the optical receiving module 14 can detect the return light beam even at small rotational angle intervals (i.e., 0.1 degrees in this embodiment), and thus the LIDAR device 10 can accurately scan the scanning area SZ. In addition, the SPAD array and the controller 21 together form a digital circuit. Therefore, the distance to the object X can be calculated without a processor, and thus the manufacturing cost of the LIDAR device 10 is reduced.

[0063] In this embodiment, the light emitting module 12 is configured to output the actual emission timing of the light beam actually emitted by the light emitting module 12. Then, the controller 21 uses the actual emission timing to correct the calculated distance. Therefore, although the distance is calculated using the signal output timing of the control signal output from the controller 21 to the light emitting module 12, and thus the calculated distance inevitably includes an error caused by the time lag between the signal output timing and the actual emission timing, the error can be corrected or compensated using the actual emission timing. Therefore, the LIDAR device 10 can obtain the distance to the object X with high accuracy.

[0064] (Second Embodiment)

[0065] Next, refer to Figures 10 to 11 Describe the second embodiment of the present disclosure. In the following description, only the parts different from the first embodiment are described.

[0066] In the first embodiment, the controller 21 is configured to output an emission control signal when receiving a detection signal from the angle sensor 28. In the second embodiment, the controller 21 is configured to: when receiving a detection signal from the angle sensor 28, output a plurality of control signals to the light emitting module 12 before receiving one of the subsequent detection signals.

[0067] More specifically, as Figure 10As shown, the controller 21 outputs a predetermined number of control signals within each rotation angle interval (i.e., between when the controller 21 receives a detection signal and when the controller 21 receives a subsequent detection signal). In this embodiment, the number of control signals output within the rotation angle interval is 10. Further, the controller 21 continuously outputs control signals ten times at a predetermined "time" interval (not a rotation angle interval), and then stops outputting control signals when the tenth control signal is output.

[0068] The controller 21 is also configured to: for each rotation angle interval, calculate the distance to the object X using a plurality of return signals corresponding to the plurality of control signals. For example, the controller 21 calculates ten distances corresponding to ten control signals for each rotation angle interval. Then, the controller 21 accumulates the ten distances and obtains an average distance based on the calculated ten distances.

[0069] Figure 11 A flowchart of the processing performed by the LIDAR device 10 according to the second embodiment is shown. It should be noted that in the second embodiment, the steps for correcting the calculated distance using the actual emission timing (i.e., Figure 7 steps S50 and S90 in

[0070] At step S100, when the angle sensor 28 detects the rotation angle of the scanning mirror 16, at step S110, the angle sensor 28 outputs a detection signal indicating the detected rotation angle to the controller 21. At step S120, when the controller 21 receives the detection signal from the angle sensor 28, the controller 21 outputs a transmission control signal to the light emitting module 12.

[0071] At step S130, when the light emitting module 12 receives the transmission control signal, the light emitting module 12 emits a laser beam toward the scanning mirror 16. The emitted laser beam is reflected at the reflecting surface of the scanning mirror 16 and travels to the scanning area SZ. Then, if the laser beam is reflected by the object X, the return beam returns to the LIDAR device and is again reflected by the reflecting surface 16a of the scanning mirror 16 toward the light receiving module 14. At step S140, when the return beam reaches the light receiving module 14, the light receiving module 14 detects the return beam, and then at step S150 the light receiving module 14 outputs a return signal to the controller 21 in response to receiving the return beam.

[0072] At step S160, the controller 21 calculates the distance to the object X using the signal output timing and the return signal. Then, at step S170, the controller 21 determines whether the number of emission control signals emitted after receiving the detection signal is ten. If the number is not ten (step S170: No), the process proceeds to step S180, and the controller 21 determines whether a predetermined time interval (e.g., 3 microseconds) has elapsed after outputting the emission control signal. If the time interval has not elapsed (step S180: No), the controller 21 repeats step S180. If the time interval has elapsed (step S180: Yes), the process proceeds to step S120, and the controller 21 outputs the emission control signal again. Next, the process repeats steps S120 to S160, and the controller 21 determines whether the number of emitted emission control signals is ten. At step S170, if the number is ten, then at step S190, the controller 21 stops outputting the emission control signal, and then at step S200, the controller 21 calculates the average distance based on the calculated ten distances. Then, the process returns to step S100.

[0073] As described above, the LIDAR device 10 according to the second embodiment outputs a plurality of emission control signals when receiving the detection signal from the angle sensor 28 until a subsequent detection signal is received. Then, the controller 21 calculates a plurality of distances to the object X based on the plurality of return signals corresponding to the plurality of emission control signals, and obtains the average distance according to the calculated plurality of distances. Therefore, the LIDAR device 10 can obtain the distance to the object X with high accuracy.

[0074] (Third Embodiment)

[0075] Next, refer to Figures 12 to 13 Describe the third embodiment of the present disclosure. In the following description, only the parts different from the first and second embodiments are described.

[0076] In the second embodiment, the controller 21 is configured to output a predetermined number (e.g., ten) of emission control signals after receiving the detection signal until a subsequent detection signal is received. In the third embodiment, the controller 21 is configured to continuously output the emission control signal at a predetermined time interval after receiving the detection signal until a subsequent detection signal is received (see Figure 12 ).

[0077] Similar to the second embodiment, the controller 21 calculates a plurality of distances to the object X for each rotation angle interval based on the plurality of return signals corresponding to the plurality of emission control signals, and then obtains the average distance according to the calculated plurality of distances.

[0078] Figure 13FIG. 0 shows a flowchart of the processing performed by the LIDAR device 10 according to the third embodiment. It should be noted that, as in the second embodiment, the steps for correcting the calculated distance using the actual emission timing (i.e., Figure 7 steps S50 and S90 in

[0079] are eliminated).

[0080] At step S300, when the angle sensor 28 detects the rotation angle of the scanning mirror 16, at step S310, the angle sensor 28 outputs a detection signal indicating the detected rotation angle to the controller 21. At step S320, when the controller 21 receives the detection signal from the angle sensor 28, the controller 21 outputs a transmission control signal to the light emitting module 12. At step S330, when the light emitting module 12 receives the transmission control signal, the light emitting module 12 emits a laser beam toward the scanning mirror 16.

[0081] At step S340, when the return beam reaches the light receiving module 14, the light receiving module 14 detects the return beam, and then at step S350, the light receiving module 14 outputs a return signal to the controller 21 in response to receiving the return beam.

[0082] At step 360, the controller 21 calculates the distance to the object X using the signal output timing and the return signal. Then at S370, the controller 21 determines whether the controller 21 has received a subsequent detection signal from the angle sensor 28 after receiving the previous detection signal. If step S370 is NO, the process proceeds to step S380, and then the controller 21 determines whether a predetermined time interval (e.g., 3 microseconds) has elapsed after outputting the transmission control signal. If the time interval has not elapsed (step S380: NO), the controller 21 repeats step S380. If the time interval has elapsed (step S380: YES), the process returns to step S320, and the controller 21 outputs the transmission control signal again. Then, the process repeats steps S320 to S370, and the controller 21 outputs a plurality of transmission control signals at a predetermined time interval until a subsequent detection signal is received.

[0083] As described above, the LIDAR device 10 according to the third embodiment continuously outputs a plurality of emission control signals at a predetermined time interval for each rotation angle interval. Then, the controller 21 calculates a plurality of distances to the object X based on the plurality of return signals corresponding to the plurality of emission control signals for each rotation angle interval, and obtains an average distance based on the calculated plurality of distances. Therefore, like the second embodiment, the LIDAR device 10 can obtain the distance to the object X with high accuracy.

[0084] (Fourth Embodiment)

[0085] Next, refer to Figures 14 to 15 to describe the fourth embodiment of the present disclosure. In the following description, only the parts different from the first to third embodiments are described.

[0086] In the first embodiment, the controller 21 is configured to automatically output an emission control signal when receiving a detection signal from the angle sensor 28. In the fourth embodiment, the controller 21 is configured to output an emission control signal if the detection signal (rotation angle) matches any one of a plurality of target rotation angles (see Figure 14 ). In this embodiment, the target rotation angles are set to, for example, 0.0 degrees, 0.2 degrees, 0.4 degrees, 0.6 degrees,..., 120.00 degrees.

[0087] Figure 15 A flowchart of the process performed by the LIDAR device 10 according to the fourth embodiment is shown. It should be noted that the steps for correcting the calculated distance using the actual emission timing (i.e., Figure 7 steps S50 to S90) are eliminated in the fourth embodiment.

[0088] At step S400, when the angle sensor 28 detects the rotation angle of the scanning mirror 16, at step S410, the angle sensor 28 outputs a detection signal indicating the detected rotation angle to the controller 21. When the controller 21 receives the detection signal from the angle sensor 28, at step S420, the controller 21 determines whether the detection signal matches any one of the target rotation angles. If the answer at step S420 is no, the process returns to step S400 and steps S410 to S420 are repeated. At step S430, if the answer at step S420 is yes, the controller 21 outputs an emission control signal to the light emitting module 12.

[0089] At step S440, when the light emitting module 12 receives the emission control signal, the light emitting module 12 emits a laser beam toward the scanning mirror 16. Accordingly, when the scanning mirror 16 is at a desired rotation angle, the LIDAR device 10 can emit a laser beam. At step S450, when the return beam reaches the light receiving module 14, the light receiving module 14 detects the return beam, and then at step S460, the light receiving module 14 outputs a return signal to the controller 21 in response to receiving the return beam.

[0090] At step S470, the controller 21 calculates the distance to the object X using the signal output timing and the return signal. Then, the process returns to step S400 and steps S410 to S470 are repeated.

[0091] As described above, when the rotation angle matches any one of the plurality of target rotation angles, the LIDAR device 10 according to the fourth embodiment outputs an emission control signal. Accordingly, the LIDAR can accurately emit a laser beam toward a desired area in the scanning area SZ.

[0092] In the fourth embodiment described above, the target rotation angles are set in a regular manner (e.g., 0.0, 0.2, 0.4, etc.). However, the target rotation angles can be set in an irregular manner using, for example, a predetermined target angle table stored in at least one memory. In this case, at least one processor can be used to determine whether the detection signal (rotation angle) matches the target rotation angle.

[0093] (Fifth Embodiment)

[0094] Next, refer to Figures 16 to 18 Describe a fifth embodiment of the present disclosure. In the following description, only the parts different from the first to fourth embodiments are described. In the above embodiments, the LIDAR device 10 emits laser light in a constant manner for each rotation angle interval (e.g., emits one laser beam for each rotation angle interval in the first embodiment, and emits a plurality of laser beams for each rotation angle interval in the second and third embodiments). In the fifth embodiment, the LIDAR device 10 is configured to emit laser beams in different ways for a specific target area and the remaining area within the scanning area SZ.

[0095] In this embodiment, a specific rotation angle range corresponding to the target area of the scanning mirror 16 is defined within the rotation angle range (e.g., -20° ≤ specific rotation angle θ ≤ +20°). As Figure 17As shown, the light-emitting module 12 is configured to emit a laser beam in a different manner within a specific rotation angle range compared to other rotation angle ranges (e.g., -60° ≤ θ < -20° and +20° < θ ≤ +60°). For example, the light-emitting module 12 is controlled to emit a predetermined number of laser beams (e.g., 10) for each rotation angle interval within a specific rotation angle range. Hereinafter, the rotation angle range of the scanning mirror 16 other than the specific rotation angle range is referred to as the normal range, in which, as in the first embodiment, the light-emitting module is controlled to emit a laser beam when receiving a detection signal from the angle sensor 28.

[0096] In this embodiment, as Figure 16 shown, the controller 21 is provided separately from the light-receiving module 14. That is, the light-receiving module 14 does not integrally include the controller 21 as described in the first embodiment. In this embodiment, the controller 21 is an electronic control unit (ECU) including at least one processor 21a and at least one memory 21b, rather than at least one circuit or a combination with at least one circuit. The memory 21b includes a random access memory, a read-only memory, a flash memory, or a combination thereof. The memory 21b has instructions stored thereon, which when executed by the processor 21a cause the processor 21a to perform various tasks as will be described later. The memory 21b also stores a specific rotation angle range.

[0097] Figure 18 A flowchart executed by the LIDAR device 10 according to this embodiment is shown. It should be noted that the steps for correcting the calculated distance using the actual emission timing (i.e., Figure 7 steps S50 and S90 in

[0098] are eliminated in the fifth embodiment. At step S500, when the angle sensor 28 detects the rotation angle of the scanning mirror 16, at step S510, the angle sensor 28 outputs a detection signal. At step S520, when the controller 21 receives the detection signal from the angle sensor 28, the controller 21 (processor 21a) determines whether the rotation angle of the scanning mirror 16 is within a specific rotation angle range. If the answer is no at step S520 (the rotation angle is within the normal range), the process proceeds to step S530, and the controller 21 outputs an emission control signal. Accordingly, when the rotation angle of the scanning mirror 16 is within the normal angle range, the controller 21 outputs an emission control signal when receiving the detection signal.

[0099] At step S540, when the light emitting module 12 receives the emission control signal, the light emitting module 12 emits a laser beam towards the scanning mirror 16. Then, at step S550, when the return beam reaches the light receiving module 14, the light receiving module detects the return beam, and then, at step S560, the light receiving module 14 outputs a return signal to the controller 21 in response to receiving the return beam.

[0100] At step S570, the controller 21 calculates the distance to the object X using the signal output timing and the return signal. Then, the process returns to step S500. In this way, when the rotation angle is within the normal range, the distance to the object X is calculated for each rotation angle interval.

[0101] At step S520, if the controller 21 determines that the rotation angle is within a specific rotation angle range (step S520: Yes), the process proceeds to step S580. Then, at step S580, the controller 21 outputs an emission control signal. At step S590, when the light emitting module 12 receives the emission control signal, the light emitting module 12 emits a laser beam towards the scanning mirror 16. Then, at step S600, when the return beam reaches the light receiving module 14, the light receiving module 14 detects the return beam, and then, at step S610, the light receiving module 14 outputs a return signal to the controller 21 in response to receiving the return beam.

[0102] At step S620, if the controller 21 receives the return signal, the controller 21 calculates the distance to the object X using the return signal. Then, at step S630, the controller 21 determines whether the number of emissions of the emission control signal after receiving the detection signal is ten. If it is No at step S630, the process proceeds to step S640, and the controller 21 determines whether a predetermined time interval (e.g., 3 microseconds) has elapsed after outputting the emission control signal. If the time interval has not elapsed (step S640: No), the controller 21 repeats step S640. If the time interval has elapsed (step S640: Yes), the process proceeds to step S580, and the controller 21 outputs the emission control signal again. Then, the process repeats steps S590 to S620, and at S630, the controller 21 determines whether the number of emitted emission control signals is ten. If it is Yes at step S630, at step S650, the controller 21 stops outputting the emission control signal, and then, at step S660, the controller 21 calculates the average distance based on the calculated ten distances. Then, the process returns to step S500.

[0103] Therefore, when the rotation angle is within a specific rotation angle range, the controller 21 outputs ten emission control signals for each rotation angle interval. The controller 21 calculates ten distances based on ten return signals corresponding to the ten emission control signals. Then, the controller 21 obtains an average distance for each rotation angle interval within the specific rotation angle range according to the calculated ten distances. Therefore, the LIDAR device 10 according to the fifth embodiment can accurately scan a specific area of the scanning area SZ and obtain the distance to the object X with high accuracy for such a specific area.

[0104] (Modifications to the Embodiment)

[0105] Several modifications can be applied to the above-described embodiment.

[0106] For example, in the embodiment described above, the light emitting module is configured to emit two laser beams from two light emitting elements. However, the light emitting module can emit a laser beam from a single light emitting element, or emit three or more laser beams from three or more light emitting elements.

[0107] In the embodiment described above, the light emitting module is configured to emit a laser during the entire period of the scanning mirror (i.e., one route from the first position to the second position and another route from the second position to the first position). However, the light emitting module can be configured to emit a laser only during one route of the scanning mirror. For example, the light emitting module can be controlled to emit a laser only when the mirror swings from the first position to the second position. In this case, after the mirror moves to the second position, the mirror immediately returns quickly to the first position.

[0108] In the embodiment described above, the light receiver includes a plurality of SPADs. However, other photosensitive elements can be used. However, if the SPAD is used as the light receiver, since the SPAD can output a digital signal, as described above, there is no need to use a processor to calculate the distance to the object.

[0109] In this application, the terms "module" and "system" can include hardware components such as a housing, a fixing device, wiring, etc. Additionally, in this application, the term "processor" can refer to a circuit or circuitry that includes processing core hardware (shared, dedicated, or grouped) that executes code and memory hardware (shared, dedicated, or grouped) that stores the code executed by the processing core hardware, or a part of or includes such a circuit or circuitry. Thus, the term "processor" can be replaced by the term "circuit".

[0110] Unless explicitly identified as an order of execution, the method steps, processes, and operations described herein should not be construed as necessarily requiring execution in the particular order discussed or illustrated. It should also be understood that additional or alternative steps may be employed.

[0111] Although terms such as "first", "second", "particular", etc. are used to describe various elements, these terms are only used to distinguish one element from another. Unless the context clearly indicates otherwise, terms such as "first", "second", and other numerical terms used herein do not imply an order or sequence. Thus, without departing from the teachings of the exemplary embodiments, the first element, component, region, layer, or portion discussed below may be referred to as the second element, component, region, layer, or portion.

[0112] For ease of description, spatial relative terms such as "front", "rear", "left", "right", etc. may be used to describe the relationship of one element or feature to another element or feature as shown in the drawings. In addition to the orientation depicted in the drawings, the spatial relative terms are also intended to encompass different orientations of the device during use or operation. For example, if the sensor system in the drawings is rotated, the element described as "front / rear" will be oriented "left / right" relative to the vehicle. Thus, the exemplary term "front" can cover any direction in practice. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatial relative descriptors used herein may be interpreted accordingly.

Claims

1. A laser imaging detection and ranging device for measuring the distance to an object (X) in a predetermined scanning area (SZ), the laser imaging detection and ranging device comprises: a light source (12) configured to emit a beam for scanning the scanning area with a predetermined beam width, the beam including at least a first laser beam and a second laser beam; a mirror (16) having a reflective surface (16a) and a back surface (16b) opposite to the reflective surface, the mirror being configured to: reflect the beam emitted from the light source towards the scanning area using the reflective surface; a rotatable shaft (24) having a central axis (CX) parallel to the reflective surface of the mirror, the rotatable shaft being connected to the back surface of the mirror; and a motor (26) configured to: rotate the rotatable shaft to swing the mirror between a first position corresponding to one end (A) of the predetermined scanning area and a second position corresponding to the other end (B) of the predetermined scanning area, the incident angle of the beam with respect to the reflective surface being greater when the mirror is in the first position than when the mirror is in the second position, wherein, when the beam center (BC) is defined as the center of the beam width of the beam from the light source to the reflective surface, then one side of the beam center including the central axis of the rotatable shaft is defined as the movement area, and the light source and the mirror are arranged in a positional relationship such that when viewed in the direction of the central axis of the rotatable shaft, when the mirror is in the first position, (i) the mirror center (MC) is aligned with the beam center, the mirror center (MC) being defined as the point on the reflective surface closest to the central axis of the rotatable shaft, (ii) the first laser beam is reflected at one of the two edge portions (30) of the mirror in the width direction of the mirror, and (iii) the second laser beam is reflected at the other edge portion (30) of the two edge portions (30) of the mirror in the width direction of the mirror, and when the mirror swings between the first position and the second position, the mirror center is displaced within the movement area, wherein the second position is included and the first position is not included between the first position and the second position.

2. The laser imaging detection and ranging device according to claim 1, wherein, the light source includes two light emitting elements (20a, 20b) that jointly emit the beam.

3. The laser imaging detection and ranging device according to claim 2, wherein, the reflective surface includes: a central portion (32) including the mirror center; and a pair of edge portions (30) extending in the direction of the central axis on both sides of the central portion. When the mirror is in the second position, the light beams from the two light-emitting elements are mainly reflected by the mirror at the central portion, and when the mirror is in the first position, the light beams from the two light-emitting elements are mainly reflected by the mirror at the paired edge portions.

4. The laser imaging detection and ranging device according to claim 3, wherein, the shape of the reflective surface has a rectangular shape, a trapezoidal shape, or a shape formed by chamfering the corners of a rectangular shape.

5. The laser imaging detection and ranging device according to claim 3, wherein, the center of the mirror is the center between the paired edge portions.

6. The laser imaging detection and ranging device according to any one of claims 1 to 5, further comprising, a controller (50), the controller (50) being configured to control the motor to swing between the first position and the second position.

7. The laser imaging detection and ranging device according to any one of claims 1 to 5, wherein, the rotatable shaft has a columnar shape and includes a side surface (24a), and the side surface (24a) is connected to the back surface of the mirror via a connecting member.

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