Object detection device and object detection method

Abstract

To provide an object detection device with which it is possible to suppress false detection of presence of an object due to interference of projected light from another object detection device, even when the other object detection device is arranged face to face.SOLUTION: An object detection device comprises: a light-emitting element for projecting projection light in accordance with light projection timing; a light-receiving element for receiving reflected light of projection light having been reflected by an object and generating a light reception signal; and a controller. The controller is capable of setting a first light projection mode in which a plurality of pieces of light projection reference timing is generated so as to project light two or more times in a given cycle and light is projected taking each light projection timing as each light projection timing, and a second light projection mode in which light is projected in accordance with each light projection timing where each light projection reference timing is shifted in time. In the second light projection mode, each light projection reference timing is shifted an each light projection timing is determined so that a shift time at which each light projection reference timing is shifted changes once every given time.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to an object detection device and an object detection method for optically detecting an object.

Background Art

[0002] Conventionally, a pulse echo type distance measurement device that adjusts a slot number representing emission timing to prevent erroneous measurement by interference light is known (see Patent Document 1). In this distance measurement device, an emission signal representing emission timing is generated by a slot generation circuit based on the slot number set by a CPU, and a pulse laser beam is emitted by an emission circuit in response to this emission signal. The emitted pulse laser beam is projected by a scanner that performs scanning based on a scanner control signal given from a timing generation circuit. The time from the emission timing to the reception timing when reflected light from a preceding vehicle of the projected pulse laser beam is received is counted by a counter, and the inter-vehicle distance from the preceding vehicle is calculated by the CPU based on the counted value. The presence or absence of interference light is detected by a reception monitoring circuit based on the reception signal of the reception circuit. When interference light is detected, the slot number is changed by the CPU.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the distance measuring device of Patent Document 1 is arranged facing another distance measuring device with the same emission timing or the like, if these two distance measuring devices emit light at the same timing, the projected light from one distance measuring device may be received by the other distance measuring device, and in this case, the projected light is detected. In this case, the distance measuring device of Patent Document 1 changes the slot number and projects the projected light at different timings. However, when these two distance measuring devices change the slot number in the same manner according to the same specifications, still one distance measuring device may receive the next projected light from the other distance measuring device. In this case, one distance measuring (measurement) device may erroneously detect the presence of an object due to the interference of the projected light from the other distance measuring (measurement) device.

[0005] The present disclosure provides an object detection device and an object detection method capable of suppressing the erroneous detection of the presence of an object due to the interference of projected light from another object detection device even when another object detection device is arranged facing it.

Means for Solving the Problem

[0006] One aspect of the present disclosure includes a light emitting element that projects projected light according to a light projection timing, a light receiving element that receives reflected light reflected by an object from the projected light and generates a light reception signal, and a controller. The controller generates a plurality of light projection reference timings so as to project light a plurality of times at a constant period, and can set a first light projection mode in which each light projection reference timing is used as each light projection timing for light projection, and a second light projection mode in which light is projected according to each light projection timing obtained by shifting each light projection reference timing in time. In the second light projection mode, the object detection device is configured to shift each light projection reference timing so that the shift time for shifting each light projection reference timing changes by a fixed time each time to determine each light projection timing.

[0007] One aspect of the present disclosure includes a step of projecting projection light according to projection timing, a step of receiving reflected light reflected by an object from the projection light and generating a reception signal, a step of generating a plurality of projection reference timings so as to project light a plurality of times at a constant period, and a step of setting a projection mode. As the projection mode, a first projection mode in which each projection reference timing is used as each projection timing for projecting light, and a second projection mode in which light is projected according to each projection timing obtained by temporally shifting each projection reference timing can be set. The step of setting the projection mode includes, when the second projection mode is set as the projection mode, a step of shifting each projection reference timing to determine each projection timing such that a shift time for shifting each projection reference timing changes by a constant time. This is an object detection method.

Advantages of the Invention

[0008] According to the present disclosure, even when another object detection device is disposed opposite, it is possible to suppress misdetection of the presence of an object due to interference of projection light from another object detection device.

Brief Description of the Drawings

[0009]

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Figure 20

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, a more detailed description than necessary may be omitted. For example, detailed descriptions of well-known matters and descriptions of substantially identical configurations may be omitted. This is to avoid making the following description unnecessarily redundant and to facilitate understanding by those skilled in the art. Note that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0011] In addition, the “part” or “device” in the embodiments is not limited to a physical configuration mechanically realized by hardware alone, and also includes those in which the functions of the configuration are realized by software such as a program. Further, even if the function of one configuration is realized by two or more physical configurations, or the functions of two or more configurations are realized by, for example, one physical configuration, it does not matter.

[0012] (Process of arriving at the embodiments of the present disclosure) Suppose that a plurality of distance measuring devices (object detection devices) of a comparative example are installed facing each other as shown in FIG. 18. The distance measuring device of the comparative example is, for example, the distance measuring device of Patent Document 1. It is assumed that the distance measuring device 1XA and the distance measuring device 1XB operate asynchronously. In this case, at the timing when the distance measuring device 1XA emits the projection light A for distance measurement, the projection light B emitted by the distance measuring device 1XB for distance measurement may be received by the light receiving element of the distance measuring device 1XA. In this case, as shown in FIG. 19, when detected by a two-dimensional scan distance measuring device, for example, continuously N times and continuously M times (N and M are integers of 2 or more), within the detectable maximum time corresponding to the detectable maximum distance of the projection light B (that is, within the detection area), the distance measuring device 1XA will erroneously detect that an object exists within the detection area. That is, as shown in FIG. 20, due to interference, an erroneous detection occurs in which an object is recognized as existing although there is no object in the space (specifically, within the detection area).

[0013] In the following embodiments, an object detection device and an object detection method will be described that can suppress the misdetection of the presence of an object due to the interference of projected light from another object detection device even when another object detection device is disposed opposite.

[0014] (Embodiment) <Physical Configuration of Object Detection Device> FIG. 1 is an external perspective view of an object detection device 1 according to Embodiment 1. FIG. 2A is a longitudinal sectional view of the object detection device according to Embodiment 1. FIG. 2A corresponds to a cross-sectional view taken along line A-A in the object detection device 1 shown in FIG. 1. FIG. 2B is a top view of the object detection device 1 shown in FIG. 1 as viewed from above. In FIG. 2B, some members such as the housing are shown with omission.

[0015] The object detection device 1 is, for example, a LiDAR (Light Detection And Ranging) device. The object detection device 1 optically detects an object to be detected or measures (ranges) the distance to the object to be detected using light such as laser light. The object detection device 1 two-dimensionally scans (scans) using light in a scanner method to perform object detection and ranging.

[0016] As shown in FIGS. 1 and 2A, the object detection device 1 includes a fixed portion 100, a rotating portion 300, and an outer cover portion 10.

[0017] The fixed portion 100 has a substantially rectangular parallelepiped shape. The rotating portion 300 is connected to the upper surface of the fixed portion 100 and has a cylindrical shape that rotates about an axis perpendicular to the upper surface with the rotation axis C. The outer cover portion 10 has a substantially cylindrical shape and covers the rotating portion 300 from above. The outer cover portion 10 has a wavelength window 11 formed using a wavelength selection member at at least a part of the side surface. The wavelength selection member is a material that transmits light having a predetermined wavelength (frequency) component used for object detection and distance measurement and blocks light having a wavelength (frequency) component in the visible region. The wavelength selection member has a role of blocking external disturbance light such as natural light and electric lights, for example.

[0018] For convenience of explanation, as shown in FIG. 1, an axis perpendicular to the upper surface (or bottom surface) of the fixed part 100 is defined as the Z axis. An axis perpendicular to the Z axis is defined as the X axis. An axis perpendicular to the Z axis and the X axis is defined as the Y axis. Also, for convenience of explanation, the positive direction of the Z axis is referred to as "up", the negative direction of the Z axis is referred to as "down", and the direction away from the Z axis in the X-axis direction or the Y-axis direction may be referred to as "sideways". Note that these expressions regarding directions are used for convenience of explanation and are not intended to limit the posture during actual use of the structure. For example, the object detection device 1 shown in FIG. 1 may be used with its top and bottom reversed. Also, the cross-sectional view A-A shown in FIG. 2A corresponds to a cross-sectional view of the YZ plane.

[0019] The bottom surface of the fixed part 100 may be fixedly installed on a predetermined plane (for example, the floor surface or the housing surface of a predetermined device, etc.).

[0020] The rotating part 300 rotates about the central axis in the height direction (Z axis) of the cylinder as the rotation axis C. As the rotating part 300 rotates, the optical axis of the projection light (hereinafter referred to as projection light 3A) projected laterally from a part of the side surface of the rotating part 300 rotates about the rotation axis C. Accordingly, the projection light 3A and the area where object detection and distance measurement are possible with the projection light 3A (hereinafter referred to as the detection area) also rotate. As will be described later, the object detection device 1 detects whether an object exists in the detection area based on the time difference (Time of Flight (TOF)) between the timing when the projection light 3A is projected and the timing when the light reflected by the object in the detection area (hereinafter referred to as reflected light 3B) is received, and measures the distance to the object existing in the detection area. When the rotating part 300 makes one full rotation about the rotation axis C, the object detection device 1 can measure the distances to the objects existing in the detection area of 360 degrees in the surrounding lateral direction.

[0021] The fixed part 100 includes a substrate 101, a light-emitting element 102, a light-receiving element 103, a condenser lens 104, a collimator lens 105, a coil 106, and a photo interrupter 107. The rotating part 300 includes a rotating member 301, a magnet 302, and a reflecting mirror 303.

[0022] A hollow motor 402 (see FIG. 3) is formed by a coil 106 of the fixed part 100 and a magnet 302 of the rotating part 300. By driving this motor 402, the rotating part 300 rotates about the rotation axis C. As shown in FIG. 2B, a plurality of coils 106 are annularly arranged along the XY plane on the outer side in the radial direction of the rotating part 300 with the rotation axis C as the center.

[0023] As shown in FIG. 2A, the substrate 101 is, for example, a printed circuit board (PCB). A comparator 401, a TDC 500, and a controller 600 (see FIG. 3) described later are mounted on the substrate 101. Note that TDC is an abbreviation for Time to Digital Converter.

[0024] The light emitting element 102 is arranged along the rotation axis C and projects projection light 3A upward.

[0025] The collimator lens 105 corrects the projection light 3A projected from the light emitting element 102 into substantially parallel light and outputs it upward.

[0026] The reflecting mirror 303 is provided on the rotating member 301 so as to reflect the parallel light projected upward from the light emitting element 102 and corrected by the collimator lens 105 in the lateral direction (the direction along the XY plane). Since the reflecting mirror 303 rotates together with the rotating member 301, the projection light is projected (scanned) 360 degrees around the rotation axis C in the direction orthogonal to the rotation axis C (lateral direction) over time. The projection light 3A reflected by the reflecting mirror 303 passes through the wavelength window 11 of the outer cover part 10 and is projected onto the detection area.

[0027] The reflected light 3B obtained by reflecting the projection light 3A by an object passes through the wavelength window 11 of the outer cover part 10 and is reflected downward by the reflecting mirror 303.

[0028] The condenser lens 104 condenses the reflected light 3B reflected downward by the reflecting mirror 303 and outputs it downward.

[0029] The light-receiving element 103 receives the reflected light 3B condensed by the condenser lens 104.

[0030] The rotating member 301 includes a plurality of ribs 311 (slits) at regular intervals. For example, the rotating member is annular and the ribs are present at regular intervals in the circumferential direction. The photo interrupter 107 (photo coupler) is arranged so as to be able to detect the passage of one rib 311. By detecting and counting the passage of one rib 311 using the photo interrupter 107, the controller 600 described later can detect the rotation angle (rotation position) of the rotating member 301 (that is, the rotating part 300). Therefore, the photo interrupter 107 and the rib 311 can constitute a rotation angle detector 403 (see FIG. 3) described later.

[0031] <Functional configuration of the object detection device> FIG. 3 is a block diagram showing a functional configuration example of the object detection device 1 according to Embodiment 1.

[0032] The object detection device 1 includes a light-emitting element 102, a light-receiving element 103, an amplifier circuit 108, a laser drive circuit 109, a comparator 401, and a TDC 500. The object detection device 1 includes a motor 402, a rotation angle detector 403, and a motor drive circuit 404. The object detection device 1 includes a controller 600, a memory 710, a switch 720, and an external input / output circuit 730. The controller 600 has functions as a distance measurement control unit 610, a distance calculation unit 620, a rotation control unit 630, a light projection timing generation unit 640, and a light projection timing correction unit 650. Note that each part in the controller 600 may be configured as a dedicated circuit by hardware or may be functionally configured by software.

[0033] The light-emitting element 102 is constituted by, for example, a laser diode. The light-emitting element 102 receives a drive signal for driving the light-emitting element 102 from the laser drive circuit 109 and projects (emits) projection light 3A (illumination light) according to the drive signal. The light-emitting element 102 performs light projection periodically and projects the projection light 3A according to the light projection timing.

[0034] The light receiving element 103 is composed of, for example, a photodiode. The light receiving element 103 receives the reflected light 3B and outputs a light reception signal (electrical signal) according to the light reception level. The reflected light 3B can be the detected light when an object is detected, or can include the scattered light scattered by the object.

[0035] The amplification circuit 108 inputs and amplifies the light reception signal from the light receiving element 103, and increases the signal level of the light reception signal.

[0036] The laser drive circuit 109 inputs a pulse signal for instructing the light projection by the light emitting element 102 from the light projection timing correction unit 650 of the controller 600. The laser drive circuit 109 outputs a pulse-shaped drive signal corresponding to the input pulse signal (also referred to as the input pulse signal) to the light emitting element 102. Therefore, the light emitting element 102 projects the pulsed projection light 3A. In FIG. 3, the input of the input pulse signal is expressed as TDC START (START signal).

[0037] The comparator 401 inputs the amplified light reception signal from the light receiving element 103. The comparator 401 binarizes according to the signal level of this light reception signal and outputs a pulse signal (also referred to as the light reception pulse signal). The light reception pulse signal becomes a predetermined High level during the period when the level of the light reception signal is equal to or higher than a predetermined comparator threshold value (comparator slice level), and becomes a predetermined GND level during the period when the level of the light reception signal is lower than the comparator threshold value. The High level is larger than the GND level. In FIG. 3, the output of the light reception pulse signal is expressed as TDC STOP (STOP signal).

[0038] TDC500 receives the START signal from the light projection timing correction unit 650. The input timing of this START signal corresponds to the light projection timing of the projected light 3A by the light emitting element 102. TDC500 receives the STOP signal from the comparator 401. The input timing of the STOP signal corresponds to the light reception timing of the reflected light 3B by the light receiving element 103, and more specifically, corresponds to the timing when the light reception pulse signal is generated. TDC500 outputs TOF (time of flight) information based on the START signal and the STOP signal. Therefore, it can be said that TDC500 measures the time from the timing when the laser drive circuit 109 is driven to the timing of the signal change from the comparator 401. Also, TDC500 may output information on the pulse width of the received light signal.

[0039] The motor 402 applies a driving force for rotating the rotating unit 300 to the rotating unit 300 based on the motor drive signal from the motor drive circuit 404. By rotating the rotating unit 300 with this driving force, the motor 402 can change the light projection direction of the projected light 3A in an arbitrary direction and can change the light reception direction of the reflected light 3B in an arbitrary direction. The rotation angle detector 403 detects the rotation angle of the rotating unit 300. This rotation angle indicates the angle with respect to a predetermined reference angle. The rotation angle detector 403 may detect the rotation speed of the motor 402. The motor drive circuit 404 generates a drive signal for driving the motor 402 based on the rotation control signal from the rotation control unit 630 of the controller 600 and sends it to the motor 402.

[0040] The controller 600 may be configured to include an MPU (Micro Processing Unit), a CPU (Central Processing Unit), a DSP (Digital Signal Processor), etc. The controller 600 may be constituted by various integrated circuits (for example, LSI (Large Scale Integration), FPGA (Field Programmable Gate Array)). The controller 600 realizes various functions by executing a program held in a memory disposed inside or outside the controller 600. The controller 600 has, as various functional units, a distance measurement control unit 610, a distance calculation unit 620, a rotation control unit 630, a light projection timing generation unit 640, a light projection timing correction unit 650, and the like.

[0041] The distance measurement control unit 610 controls the distance measurement by the object detection device 1 and comprehensively controls each unit within the controller 600. Further, the distance measurement control unit 610 inputs the information obtained from the memory 710 and the switch 720 as parameters for performing various processes and controls by the controller 600. Further, the distance measurement control unit 610 outputs the information of the result of various processes and controls performed by the controller 600 to the external input / output circuit 730.

[0042] The distance calculation unit 620 acquires information on TOF and pulse width from the TDC 500. The distance calculation unit 620 calculates, for example, the distance from the object detection device 1 to the object by converting the TOF (temporal digital value) into a distance based on the acquired TOF and the speed of light. This distance is a distance value measured according to the TOF and is also referred to as a measured distance value.

[0043] Further, the distance calculation unit 620 may acquire, from the rotation angle detector 403 or the like, or derive by calculation, information on the rotation angle corresponding to the light projection timing corresponding to the START signal that is the basis of the TOF corresponding to the measured distance value. The distance calculation unit 620 may specify the two-dimensional position of the object based on the measured distance value and the obtained rotation angle.

[0044] The rotation control unit 630 controls the rotation of the motor 402, that is, the rotation of the rotating unit 300. Specifically, the rotation control unit 630 sends a rotation control signal for controlling the rotation of the motor 402 to the motor drive circuit 404. The rotation control unit 630 generates a rotation control signal for rotating the motor 402 at a constant speed based on the rotation angle information and rotation speed information from the rotation angle detector 403. That is, the rotation control unit 630 rotates the motor 402 and the rotating unit 300 at a constant speed.

[0045] The light projection timing generation unit 640 acquires the rotation angle and rotation speed information detected by the rotation angle detector 403. The light projection timing generation unit 640 generates a light projection reference timing (light emission reference timing) based on the acquired rotation angle, or the rotation angle and rotation speed. The light projection reference timing is the reference light projection timing (light emission timing) by the light emitting element 102.

[0046] For example, the light projection timing generation unit 640 may generate the light projection reference timing so that the light emitting element 102 projects light at a timing when the detected rotation angle is a predetermined angle (for example, 0.5 degrees, 1.0 degrees, 1.5 degrees,... with respect to the reference angle). That is, the light projection timing generation unit 640 may acquire the rotation angle detected by the rotation angle detector 403 and determine a fixed period during which the light projection reference timing is generated based on the rotation angle.

[0047] For example, the light projection timing generation unit 640 may generate the light projection reference timing at a fixed period of the clock generated by a clock generator (not shown), that is, at a predetermined time interval (for example, a time interval corresponding to 0.5 degrees, 1.0 degrees, 1.5 degrees,... with respect to the reference angle), so that the light emitting element 102 projects light. That is, the light projection timing generation unit 640 may acquire the clock generated by the clock generator and determine a fixed period during which the light projection reference timing is generated based on the clock.

[0048] According to the generation of the light projection reference timing based on the clock, even if the rotation of the rotating unit 300 is not at a constant speed, the light emitting element 102 can project light at a constant period. Also, according to the generation of the light projection reference timing based on the rotation angle, even if the clock generation is not at a constant period, the light emitting element 102 can project light at a constant period.

[0049] The light projection timing correction unit 650 corrects the light projection reference timing generated by the light projection timing generation unit 640 by temporally shifting it, and determines the light projection timing. The temporal amount (also referred to as the shift amount or shift time) by which the light projection reference timing is shifted by the correction varies depending on each light projection reference timing. For example, the shift time may vary according to how many degrees the rotating unit 300 is with respect to the reference angle (e.g., 0.5 degrees, 1.0 degrees,...). In the correction of a plurality of light projection reference timings, a plurality of light projection reference timings with different shift times in which the light projection timings are temporally shifted from each other may be included, or a plurality of light projection reference timings with the same shift time may be included. When the shift times are different, for example, the light projection timings before and after in succession are determined so that the shift times differ by a fixed time α each time. Also, among the plurality of generated light projection reference timings, there may be those in which the light projection reference timing is not corrected and the light projection reference timing is directly determined as the light projection timing.

[0050] The memory 710 may be, for example, a non-volatile memory, and may also include other memories and storage devices. The memory 710 holds various data, information, programs, etc. The memory 710 may hold, for example, area information regarding the detection area DR. The detection area DR is an area formed in a circular or fan shape around the object detection device 1, and is an area in which the object detection device 1 can detect an object and measure the distance. The area information may include information such as the position and size of the detection area DR. The size of the detection area DR is determined by the length of the radius of the detection area DR. This radius is the maximum distance at which the object detection device 1 can detect an object, and is also referred to as the area detection setting distance DL.

[0051] The memory 710 may include light projection mode information regarding the light projection modes described later. The light projection mode information may include at least one piece of information such as each light projection reference timing at which the light emitting element 102 projects light, a shift amount (shift time) for temporally shifting each light projection reference timing, and each light projection timing obtained by correcting each light projection reference timing. The light projection mode information may be held in the memory 710 for each light projection mode.

[0052] The switch 720 is, for example, a DIP switch or other switch and inputs various types of information. Note that instead of the switch 720, an input device (for example, a button, a key, a touch panel) capable of inputting various types of information may be provided in the object detection device 1. The switch 720 designates, for example, a detection area.

[0053] The external input / output circuit 730 communicates with an external device (for example, a PLC (programmable logic controller)) via wire or wirelessly. The external input / output circuit 730 gives an instruction from the external device and notifies the external device.

[0054] <Outline of Light Projection Modes> Next, an outline of the light projection modes will be described.

[0055] The distance measurement control unit 610 of the controller 600 sets a light projection mode that determines how the light emitting element 102 projects light. The light projection modes include a normal light projection mode and a shift light projection mode.

[0056] The normal light projection mode is a light projection mode in which each generated light projection reference timing is used as each light projection timing without being shifted, and light is projected according to each light projection timing. Therefore, in the normal light projection mode, the projected light 3A is projected at a constant period.

[0057] The shift projection mode is a projection mode that corrects each generated light projection reference timing and projects light according to each corrected light projection timing. In the shift projection mode, the light projection reference timing is corrected so that the shift time shifted from the light projection reference timing changes by a fixed time α each time, that is, changes by an integer multiple of α. The shift projection mode may include a plurality of shift projection modes based on the way of correction for correcting the light projection reference timing, for example, based on the way of change in the shift amount at each consecutive light projection timing. The distance measurement control unit 610 may select and set one light projection mode from among the plurality of light projection modes, or may switch and set the plurality of light projection modes.

[0058] The distance measurement control unit 610 may, for example, acquire area information from the memory 710 and set the detection area. The distance measurement control unit 610 may, for example, set the light projection mode specified by the switch 720 among the light projection modes related to the light projection mode information held in the memory 710. The distance measurement control unit 610 may switch and set a plurality of light projection modes according to the designation by the switch 720.

[0059] Since the distance measurement control unit 610 can set a plurality of light projection modes and can switch and set the light projection modes, when a plurality of object detection devices 1 are arranged in their respective detection areas, even if the plurality of object detection devices 1 are asynchronous, it is possible to suppress the misrecognition that an object exists even though there is no object in the space within the detection area due to the interference by the projection light 3A projected by another object detection device 1. For example, for example, two object detection devices 1 are mounted on two AGVs (Automated Guided Vehicles), and when the two AGVs pass by each other, one object detection device 1 may receive the projection light 3A projected by the other object detection device 1. Even in this case, false detection can be suppressed. For example, when one object detection device 1 is set to the normal projection mode and the other object detection device 1 is set to the shift projection mode, there may be a possibility of receiving the projection light 3A once, but the possibility of continuously receiving it a plurality of times can be reduced, and false detection of an object can be suppressed.

[0060] In addition, the normal light projection mode is a general light projection mode. However, when there is a device that performs the same periodic light projection in other object detection devices, once interference occurs, it is likely to continue to occur. In contrast, by being set to the shift light projection mode, the object detection device 1 is less likely to interfere with other object detection devices, and even if interference occurs once, the occurrence of interference can be continuously suppressed.

[0061] <Details of Object Detection> Next, the details of object detection will be described.

[0062] FIG. 4 is a diagram for explaining the details of object detection.

[0063] In the object detection device 1, as an example, in the periodic light projection of the light emitting element 102, the light projection period is, for example, 69.444 μs (microseconds), which corresponds to 0.5 degrees. Also, as an example, the rotation frequency of the motor 402 is, for example, 20 Hz. Also, as an example, the distance conversion coefficient in TOF is 150 mm / ns.

[0064] For example, assume a case where the rotating unit 300 rotates at a constant speed and the light emitting element 102 projects light at predetermined rotation angles each time the rotation angle of the rotating unit 300 reaches a predetermined rotation angle. In this case, when each light projection reference timing is arranged on the time axis, each light projection reference timing is arranged side by side at a constant time interval (for example, 69.444 μs). On the time axis, the ranging interval (detection interval) is, for example, a time interval of 0.030 μs (microseconds) with respect to the light projection reference timing, and the non-ranging interval (non-detection interval) is, for example, a time interval of 69.414 μs. That is, if the light emitting element 102 projects the projection light 3A at the light projection reference timing and the reflected light 3B is not detected within the temporal response range of the TDC 500, the TDC 500 times out. The time until the TDC 500 times out is the maximum measurable distance range (maximum detectable range).

[0065] The distance measurement control unit 610 determines that an object exists in the detection area when, for example, based on light projection at continuous light projection timings (e.g., light projection reference timing), reflected light 3B is continuously received within the temporal response range of the TDC500. The distance measurement control unit 610 determines that no object exists in the detection area when, for example, based on light projection at continuous light projection timings (e.g., light projection reference timing), reflected light 3B is not continuously received within the temporal response range of the TDC500. Also, for example, when, based on light projection at continuous light projection timings (e.g., light projection reference timing), light other than reflected light 3B (e.g., projection light projected by another object detection device) is continuously received within the temporal response range of the TDC500, it is detected that an object exists in the detection area. This detection is a false detection.

[0066] FIG. 5 is a diagram showing an example of the position of an object existing in the detection area DR. FIG. 6 is a diagram showing an example of the light projection timing of the projection light 3A and the light reception timing of the detection light (here, the reflected light 3B) when an object exists in the detection area DR. FIG. 7 is a diagram showing an example of the position of an object existing outside the detection area DR. FIG. 8 is a diagram showing an example of the light projection timing of the projection light 3A and the light reception timing of the detection light (here, the reflected light 3B) when an object exists outside the detection area DR.

[0067] As an example, when the motor 402, that is, the rotating unit 300, rotates at a constant speed of, for example, 50 ms (milliseconds) / one rotation and is detected with a detection resolution of 0.5 degrees, the light emitting element 102 projects the projection light 3A at a constant time interval of 69.444 μs. That is, the time interval between the consecutive light projection reference timings of the light projection before and after that is not projected from the light emitting element 102 is a constant time interval of 69.444 μs.

[0068] For example, assuming the time from the point in time when the projection light 3A is projected to the point in time when the detection light is received is T(s), T(s) is the time for the light to travel to and fro, and the one-way time is half of that. Therefore, assuming the speed of light is 3.0×10 8 (m / s), the distance OL to the object is T(s)×3.0×10 8It is calculated by (m / s) / 2.

[0069] The distance measurement control unit 610 calculates the distance OL to the above object. Further, the distance measurement control unit 610 compares the distance OL to the object with the area detection set distance DL. When the distance OL to the object is less than or equal to the area detection set distance DL, the distance measurement control unit 610 determines that the object exists within the detection area DR (see FIGS. 5 and 6). When the distance OL to the object is longer than the area detection set distance DL, the distance measurement control unit 610 determines that the object exists outside the detection area DR (see FIGS. 7 and 8).

[0070] In addition, in FIGS. 6 and 8, since the temporal positional relationship is shown, when the time difference between the projected light 3A and the detected light is within the area detection set time DT corresponding to the area detection set distance DL, it indicates that it exists within the detection area DR. Also, when the time difference between the projected light 3A and the detected light is outside the area detection set time DT, it indicates that the object exists outside the detection area DR. The area detection set time DT is a time based on the longest distance possible by the projected light 3A (that is, the area detection set distance DL) and the speed of light, and is the time required for light to travel to and from the area detection set distance DL. Therefore, it is a value obtained by dividing twice the area detection set distance DL by the speed of light (that is, area detection set distance DL×2 / speed of light). Note that the area detection set time DT starts timing immediately after the projection of the projected light 3A.

[0071] <Details of the normal projection mode> Next, the details of the normal projection mode will be described.

[0072] In the normal projection mode, the projection timing generation unit 640 generates each projection reference timing at a predetermined rotation angle, that is, at regular time intervals, and the projection timing correction unit 650 determines each projection reference timing as each projection timing without temporally shifting each projection reference timing.

[0073] FIG. 9 is a diagram showing a first example of the light projection timing and the light reception timing in the normal light projection mode. FIG. 10 is a diagram showing a second example of the light projection timing and the light reception timing in the normal light projection mode. FIG. 11 is a diagram showing a third example of the light projection timing and the light reception timing in the normal light projection mode.

[0074] In FIGS. 9 to 11, as an example, each time the light projection timing generation unit 640 rotates by 0.5 degrees with respect to the reference angle X degrees, that is, at X + 0.5 degrees, X + 1.0 degrees, etc., the light projection reference timing is generated so as to project the projection light 3A.

[0075] Also, in FIGS. 9 and 10, as a detection condition for detecting an object, it is necessary to detect the width of the object. Therefore, it is necessary to continuously detect the detection light at a plurality of points. When the detection light is received continuously N times within the area detection setting time DT for each projection light 3A, it is determined that an object exists in the detection area DR. Here, as an example, N = 2.

[0076] More specifically, the detection condition may include a condition for determining that an object exists (may exist). As this condition, since it is necessary to detect the width of the object, it may include a condition of continuously detecting at a plurality of points. The detection condition may include a condition for determining that an object exists. As this condition, it may include detecting the width of the object in a plurality of cycles (M cycles). In this case, detecting in a plurality of cycles may include detecting at different angles in a plurality of cycles (for example, the first cycle and other cycles). Note that even if the number of consecutive points is different as long as detection is performed continuously at a plurality of points in each of the M cycles. Note that the plurality of cycles here may be consecutive cycles or non-consecutive cycles.

[0077] In Fig. 9, at X + 0.5 degrees, X + 1.0 degrees, X + 1.5 degrees, and X + 2.0 degrees, reflected light 3B is received at a time point after the point in time until the area detection setting time DT has elapsed (also referred to as the time point when the area detection setting time DT has elapsed). Therefore, since no reflected light 3B (detection light) has been received within the area detection setting time DT for the projected light 3A projected at consecutive light projection reference timings, the distance measurement control unit 610 determines that there is no object in the detection area DR. Thus, the detection condition may include a condition for determining that there is no object. This condition may include, for example, not detecting the width of the object (i.e., no detection at multiple consecutive points), and not detecting the width of the object continuously for multiple rounds.

[0078] In Fig. 10, at X + 0.5 degrees and X + 2.0 degrees, reflected light 3B is received at a time after the time point when the area detection setting time DT has elapsed. Also, at X + 1.0 degrees and X + 1.5 degrees, reflected light 3B is received at a time point before the time point when the area detection setting time DT has elapsed. Therefore, since the reflected light 3B (detection light) is continuously received within the area detection setting time DT for the projected light 3A projected at consecutive light projection reference timings, the distance measurement control unit 610 determines that there is an object in the detection area DR.

[0079] In Fig. 11, as a detection condition for detecting an object, it is assumed that when the detection light is received within the area detection setting time DT for each projected light 3A continuously N times and continuously for M rounds of rotation of the rotating unit 300, it is determined that there is an object in the detection area DR. For example, here, as an example, N = 2 and M = 2. Also, since the object may be moving, the position where the object is detected may be at different angles or in different ranges.

[0080] In FIG. 11, regardless of whether the rotation of the rotating part 300 is the Y-th round or the (Y + 1)-th round, as in FIG. 10, at X + 1.0 degrees and X + 1.5 degrees, the reflected light 3B is received at a time point before the elapse of the area detection setting time DT. That is, in FIG. 11, the detection light is received twice continuously and twice continuously around, and the reflected light 3B is received at a time point before the elapse of the area detection setting time DT. Therefore, the distance measurement control unit 610 determines that an object exists in the detection area DR.

[0081] In this way, the object detection device 1 can suppress the misdetection of an object such as floating dust that does not actually exist by strictifying the object detection conditions. For example, the object detection device 1 detects the presence or absence of an object in the detection area DR for each detection resolution. When the detection light is received before the elapse of the area detection setting time DT continuously N times and continuously M rounds (N and M are 2 or more), the distance measurement control unit 610 determines that an object exists in the detection area DR. Then, the distance measurement control unit 610 outputs the determination result to the external input / output circuit 730. The external input / output circuit 730 notifies the external device of the information of this determination result.

[0082] <Details of the Shift Projection Mode> Next, the details of the shift projection mode SM will be described. The shift projection mode SM may include one or more shift projection modes SM in which the method of correcting each projection reference timing is different. The shift projection mode SM may include at least one of shift projection modes SM1 to SM5 as described later, for example.

[0083] In the shift projection mode, as in the normal projection mode, the projection timing generation unit 640 generates a plurality of projection reference timings so as to project a plurality of times at a constant period. Further, the projection timing correction unit 650 shifts each projection reference timing so that the shift time for shifting each projection reference timing changes by a constant time α longer than the area detection setting time DT, and determines each projection timing.

[0084] In the shift light projection mode, the light projection timing generation unit 640 may generate a plurality of light projection reference timings so as to perform light projection at every certain angle (for example, every 0.5 degrees) in the rotation by the rotation unit 300. The light projection timing correction unit 650 may shift each light projection reference timing at every certain angle so that the shift time for shifting each light projection reference timing changes by a constant time α each time, and determine each light projection timing.

[0085] FIG. 12 is a diagram showing an example of the light projection timing and the light reception timing when the shift light projection mode SM1 is specified. FIG. 13 is a diagram showing an example of the light projection timing and the light reception timing when the shift light projection mode SM2 is specified. FIG. 14 is a diagram showing an example of the light projection timing and the light reception timing when the shift light projection mode SM3 is specified. FIG. 15 is a diagram showing an example of the light projection timing and the light reception timing when the shift light projection mode SM4 is specified. FIG. 16 is a diagram showing an example of the light projection timing and the light reception timing when the shift light projection mode SM5 is specified.

[0086] In FIGS. 12 to 16, as an example, the light projection timing generation unit 640 generates light projection reference timings so as to project the projection light 3A at every 0.5-degree rotation with respect to the reference angle X degrees, that is, at X + 0.5 degrees, X + 1.0 degrees,.... The light projection angle of the k-th light projection is X + k × 0.5 (degrees). For example, in order to perform light projection at an angle of 160 degrees to 200 degrees, X = 159.5 degrees and k = 1 to 81. Assuming the maximum number of light emission times is Kmax, the number of light emission times is 81 times.

[0087] Also, in FIGS. 12 to 16, as a detection condition for detecting an object, it is assumed that when the detection light is received continuously N times with respect to each projection light 3A within the area detection setting time DT corresponding to the area detection setting distance DL, it is determined that an object exists in the detection area DR. Here, as an example, N = 2.

[0088] As an example, assuming that the motor 402, i.e., the rotating part 300, rotates at a constant speed of, for example, 50 ms (milliseconds) per rotation and is detected with a detection resolution of 0.5 degrees, the light emitting element 102 projects the projection light 3A at a constant time interval of 69.444 μs. That is, the time interval between the successive front and rear light projection reference timings projected by the light emitting element 102 is a constant time interval of 69.444 μs.

[0089] Also, in FIGS. 12 to 16, it is assumed that a plurality of object detection devices 1 (1A, 1B) are arranged to face each other. Therefore, the object detection device 1A can receive the projection light 3A projected by the object detection device 1B. It is assumed that the object detection device 1A is set to any one of the shift light projection modes and projects the projection light 3A with the light projection timing shifted at a constant period. It is assumed that the object detection device 1B is set to the normal light projection mode and projects the projection light 3A at a constant period. In FIGS. 12 to 16, the projection light 3A projected by the object detection device 1A is shown as "LA", and the projection light 3A projected by the object detection device 1B is shown as "LB".

[0090] In FIG. 12, the light projection timing correction unit 650 determines each light projection timing by shifting each light projection reference timing so that the shift time increases by a constant time α each time.

[0091] In FIG. 12, assuming that the correction amount of the light projection timing as the shift time is α (ns), at the light projection timing of the projection light 3A at X + 0.5 degrees for the first emission, the shift time is 0 × α. At the light projection timing of the projection light 3A at X + 1.0 degrees for the second emission, the shift time is 1 × α. At the light projection timing of the projection light 3A at X + k × 0.5 degrees for the k-th emission, the shift time is (k - 1) × α. That is, the light projection timing correction unit 650 can gradually shift the light projection timing to a later time by increasing the shift time by a constant time α each time and adding this gradually increasing shift time to each light projection reference timing.

[0092] As a result, the object detection device 1 can correct the light projection timing while minimizing the temporal shift from the light projection reference timing, and can shift the light projection timing so as to be close to the originally planned light projection timing. Also, in FIG. 12, detection light (here, the projection light 3A of the object detection device 1B) is received within the area detection setting time DT with respect to the first projection light 3A. However, detection light is not received within the area detection setting time DT after the second projection. Therefore, the object detection device 1 can suppress false detection of the presence of an object.

[0093] In FIG. 13, the light projection timing correction unit 650 determines each light projection timing by shifting each light projection reference timing so that the shift time decreases by a fixed time α each time.

[0094] In FIG. 13, if the correction amount of the light projection timing as the shift time is α (ns), then at the light projection timing of the projection light 3A at X + 0.5 degrees for the first projection, the shift time is (Kmax - 1) × α. At the light projection timing of the projection light 3A at X + 1.0 degrees for the second projection, the shift time is (Kmax - 2) × α. At the light projection timing of the projection light 3A at X + k × 0.5 degrees for the k-th projection, the shift time is (Kmax - k) × α. At the light projection timing of the projection light 3A at X + Kmax × 0.5 degrees for the Kmax-th projection, the shift time is 0 × α. That is, the light projection timing correction unit 650 can gradually shift the light projection timing to an earlier time by shortening the shift time by a fixed time α each time and adding this gradually decreasing shift time to each light projection reference timing.

[0095] As a result, at the light projection timings in the early stages such as the first and second projections, the object detection device 1 is highly likely to avoid receiving the projection light 3A from another object detection device 1 (here, the object detection device 1B) within the area detection setting time DT, and can reduce the possibility of misrecognizing the presence of an object.

[0096] In FIG. 14, the light projection timing correction unit 650 may shift each light projection reference timing so that the shift time increases by a fixed time α for a predetermined number of shift times (for example, n times). Then, after the end of the predetermined number of shift times, the light projection timing correction unit 650 may return the light projection timing to the light projection reference timing and repeat the same shift of each light projection reference timing for the predetermined number of shift times to determine each light projection timing. In FIG. 14, n = 3 is illustrated as an example.

[0097] Specifically, in order to repeat the shift a number of times (n times), the shift time can be repeated by shifting at the time of the k-th light projection by the number of the remainder when (k - 1) is divided by n. Assume that the function that outputs the number of the remainder of (k - 1)÷n is MOD((k - 1), n), and the correction amount of the light projection timing as the shift time is α (ns). Also, in FIG. 14, n = 3. In this case, at the light projection timing of the projected light 3A at X + 0.5 degrees for the first time, the shift time is MOD(0, 3)×α (= 0×α). At the light projection timing of the projected light 3A at X + 1.0 degrees for the second time, the shift time is MOD(1, 3)×α (= 1×α). At the light projection timing of the projected light 3A at X + 1.5 degrees for the third time, the shift time is MOD(2, 3)×α (= 2×α). At the light projection timing of the projected light 3A at X + 1.0 degrees for the third time, the shift time is MOD(2, 3)×α (= 2×α). At the light projection timing of the projected light 3A at X + 2.0 degrees for the fourth time, the shift time is MOD(3, 3)×α (= 0×α). Therefore, when n = 3, it can be repeated three times. Therefore, at the light projection timing of the projected light 3A at X + k×0.5 degrees for the k-th time, the shift time is MOD((k - 1), n)×α.

[0098] That is, the light projection timing correction unit 650 gradually shifts the light projection timing to a later time by increasing the shift time by a fixed time α for each light projection reference timing for a predetermined number of shift times and adding this gradually increasing shift time to each light projection reference timing. After that, the light projection timing correction unit 650 resets the temporal shift of the light projection reference timing and gradually shifts the light projection timing to a later time again by a fixed time α each time. Therefore, the object detection device 1 can suppress the shift time from being accumulated and becoming too long, and can suppress the reduction in the light projection frequency of the projected light 3A.

[0099] In FIG. 15, the light projection timing correction unit 650 may shift each light projection reference timing so that the shift time becomes shorter by a fixed time α for a predetermined number of shift times (for example, n times). Then, after the end of the predetermined number of shift times, the light projection timing correction unit 650 may return the light projection timing to the light projection reference timing and repeat the same shift of each light projection reference timing for the predetermined number of shift times to determine each light projection timing. In FIG. 15, n = 3 is illustrated as an example.

[0100] Specifically, to repeat by the number of shift times (n times), the shift time can be repeated by shifting at the light projection time of the k-th time by a value obtained by subtracting the remainder when (k - 1) is divided by n from n. Assume that the function for outputting the remainder of (k - 1)÷n is MOD(k - 1, n), and let the correction amount of the light projection timing as the shift time be α (ns). Also, assume n = 3 in FIG. 15. In this case, at the light projection timing of the projected light 3A at X + 0.5 degrees for the first time, the shift time is (3 - (MOD(0, 3)))×α (= 3×α). At the light projection timing of the projected light 3A at X + 1.0 degrees for the second time, the shift time is 3 - (MOD(1, 3))×α (= 2×α). At the light projection timing of the projected light 3A at X + 1.5 degrees for the third time, the shift time is 3 - (MOD(2, 3))×α (= 1×α). At the light projection timing of the projected light 3A at X + 2.0 degrees for the fourth time, the shift time is 3 - (MOD(3, 3))×α (= 3×α). Therefore, when n = 3, it can be repeated 3 times. Thus, at the light projection timing of the projected light 3A at X + k×0.5 degrees for the k-th time, the shift time is (n - (MOD((k - 1), n)))×α.

[0101] That is, the light projection timing correction unit 650 shortens the shift time by a fixed time α for a predetermined number of shift times, and adds this gradually shortening shift time to each light projection reference timing, thereby gradually shifting the light projection timing to an earlier time. After that, the light projection timing correction unit 650 resets the temporal shift of the light projection reference timing, and gradually shifts the light projection timing to an earlier time again by a fixed time α. Therefore, the object detection device 1 can suppress the shift time from becoming short, and it becomes easier to ensure the time interval between the light projection reference timing and the corrected light projection timing. Therefore, the object detection device 1 has a high possibility of avoiding the situation where the projected light 3A from another object detection device 1 (here, the object detection device 1B) is received within the area detection setting time DT, and can reduce the possibility of misrecognition of the presence of an object.

[0102] In FIG. 16, the light projection timing correction unit 650 may determine each light projection timing by shifting each light projection reference timing so that the shift time increases (lengthens) by a fixed time α each time, and then shifting each light projection reference timing so that the shift time decreases (shortens) by a fixed time α each time. Alternatively, the light projection timing correction unit 650 may determine each light projection timing by shifting each light projection reference timing so that the shift time decreases by a fixed time α each time, and then shifting each light projection reference timing so that the shift time increases by a fixed time α each time. In FIG. 16, n = 4 is illustrated as an example.

[0103] Specifically, to repeat the shift a certain number of times (n times), for the light projection timing correction unit 650, regarding the shift time, when projecting light for the k-th time, it can handle the situation by repeating the process of switching the processing based on whether the remainder when (k - 1) is divided by n is less than n÷2 or greater than or equal to n÷2. Assume the function that outputs the remainder of (k - 1)÷n is MOD(k - 1,n), and assume the correction amount of the light projection timing as the shift time is α (ns). Also, assume n = 4 in FIG. 16. In this case, at the light projection timing of the projected light 3A at X + 0.5 degrees for the first time, MOD(0,4) = 0, which is less than n÷2 (=2), so the shift time is MOD(0,4))×α (=0×α). At the light projection timing of the projected light 3A at X + 1.0 degrees for the second time, MOD(1,4) = 1, which is less than n÷2 (=2), so the shift time is (MOD(1,4))×α (=1×α). At the light projection timing of the projected light 3A at X + 1.5 degrees for the third time, MOD(2,4) = 2, which is greater than or equal to n÷2, so the shift time is (4 - (MOD(2,4)))×α (=2×α). At the light projection timing of the projected light 3A at X + 2.0 degrees for the fourth time, MOD(3,4) = 3, which is greater than or equal to n÷2, so the shift time is (4 - (MOD(3,4)))×α (=1×α). At the light projection timing of the projected light 3A at X + 2.5 degrees for the fifth time, MOD(4,4) = 0, which is less than n÷2, so the shift time is (MOD(4,4))×α (=0×α). Therefore, at the light projection timing of the projected light 3A at X + k×0.5 degrees for the k-th time, the shift time is (MOD((k - 1),n))×α when MOD((k - 1),n) is less than n÷2, and (n - (MOD((k - 1),n)))×α when MOD((k - 1),n) is greater than or equal to n÷2. The light projection timing correction unit 650 may correct the light projection reference timing so as to repeat such a change in the shift time.

[0104] Even with such a mountain - shaped or valley - shaped light projection reference timing, the object detection device 1 can suppress receiving the projected light 3A from other object detection devices 1 within the area detection setting time DT, that is, it can suppress misrecognizing that there is an object in the detection area DR.

[0105] Note that the fixed time α is set to be longer than the time until the timeout of the TDC500 by the maximum measurable distance range (maximum detectable range). Specifically, when the maximum measurable range (maximum detectable range) is L = 4500 mm and the speed of light is 3.0 × 10^8 m / s, the time T for light to travel to and fro for L = 4500 mm is T = L × 2 ÷ speed of light = 30 (nsec). Therefore, the light projection timing correction unit 650 sets the value of α (ns), which is the basis for the shift time as the timing correction amount, to be larger than the above T.

[0106] FIG. 17 is a diagram showing an example of the light projection timing when another shift light projection mode SM6 is specified.

[0107] The light projection timing correction unit 650 determines each light projection timing by incrementally shifting in the ± direction from each light projection reference timing for each scan cycle, that is, for each rotation of the rotating unit 300, according to the shift light projection mode SM6. Here, the scan cycle may be a rotation of a predetermined angle within one rotation of the rotating unit 300 as described above, or a rotation in units of one rotation of the rotating unit 300. The shift time for incremental shifting is increased or decreased by a fixed time α as described above. The light projection timing correction unit 650 determines each light projection timing by shifting the time by a fixed time α for each scan cycle with respect to the light projection reference timing. When the light projection timing correction unit 650 determines each light projection timing after shifting by the set number of shift times, it projects light at the light projection reference timing in the next scan cycle. Thereafter, the light projection timing correction unit 650 similarly determines each light projection timing while shifting the light projection reference timing by a fixed time α each time.

[0108] Note that the fixed time α serving as the basis for the shift time needs to be longer than the time T = L×2÷speed of light = 30 (nsec) obtained from the maximum measurable range (maximum detectable range) L = 4500 mm. For example, with a 2-fold margin, it is 60 ns. In that case, the number of shifts is based on the light projection at intervals of 69.444 μs, so the maximum number of shifts is 1157 calculated from the light projection interval ÷ fixed time α.

[0109] In this way, when one object detection device 1A is set to the normal light projection mode and the other object detection device 1B is set to the shift light projection mode, as shown in FIGS. 12 to 16, the object detection device 1A can suppress the occurrence of interference caused by the projected light 3A of the other object detection device 1B and can suppress the false detection of an object.

[0110] Also, by making the shift time different as a fixed time α longer than the area detection setting time DT at two light projection timings before and after in time, for example, even if interference occurs at the previous light projection timing, the interference can be suppressed at the subsequent light projection timing. This is because the fixed time α is longer than the area detection setting time DT, so it is possible to suppress the projected light projected periodically from being received within the area detection setting time DT at the subsequent light projection timing.

[0111] When one object detection device 1A is set to the normal light projection mode and the other object detection device 1B is set to the shift light projection mode, as shown in FIGS. 12 to 16, the object detection device 1A can suppress the occurrence of interference caused by the projected light 3A of the other object detection device 1B and can suppress the false detection of an object.

[0112] Also, similar to the normal light projection mode, in the shift light projection mode, the object detection device 1 can suppress false detection of objects such as floating dust that do not actually exist by strictifying the object detection conditions. For example, the object detection device 1 detects the presence or absence of an object in the detection area DR for each detection resolution. If the detection light is received before the elapse of the area detection setting time DT for N consecutive times and M consecutive rounds (where N and M are 2 or more), the distance measurement control unit 610 determines that an object exists in the detection area DR. Then, the distance measurement control unit 610 outputs the determination result to the external input / output circuit 730. The external input / output circuit 730 notifies the external device of the information on this determination result.

[0113] In this way, the object detection device 1 of the present embodiment can be set to switch between a plurality of light projection modes, so that when a plurality of object detection devices 1 are arranged, it is possible to prevent the interference state caused by the projection light 3A projected from other object detection devices from occurring continuously. Thereby, the object detection device 1 can suppress false detection that an object exists even though there is no object in the space due to interference.

[0114] Also, by setting the shift light projection mode, the object detection device 1 can avoid interference by flexibly increasing or decreasing the light projection timing quickly. For example, even when the light projection reference timing is generated at the same fixed period, by making it possible to set different light projection modes, the probability of non-interference can be increased. When set to different light projection modes, it is possible to suppress the continuation of the interference state caused by the projection light 3A projected by other object detection devices.

[0115] Also, in order to detect the projected light as much as possible, the light reception sensitivity of the light receiving element 103 of the object detection device 1 can be increased. In this case, when a plurality of object detection devices 1 are arranged facing each other, there is a high probability of interference. Also, including stray light from production equipment and FA equipment in the factory where the object detection device 1 is installed, the possibility of interference becomes even higher. In contrast, according to the object detection device 1, it is possible to perform light projection at each light projection timing obtained by regularly correcting the light projection reference timing, and suppress the occurrence of interference.

[0116] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is obvious that those skilled in the art can conceive of various modifications or corrections within the scope described in the claims, and it is naturally understood that they also belong to the technical scope of the present invention. Further, within the scope not departing from the gist of the invention, the components in the above embodiments may be arbitrarily combined.

[0117] <Summary of this embodiment> As described above, the present disclosure describes at least the following matters. In the parentheses, the corresponding components and the like in the above-described embodiments are exemplified, but the present disclosure is not limited thereto.

[0118] (Item 1) A light-emitting element (light-emitting element 102) that projects projection light (projection light 3A) according to projection timing, A light-receiving element (light-receiving element 103) that receives the reflected light obtained by reflecting the projection light by an object and generates a light-receiving signal, A controller (controller 600), and The controller Generates a plurality of projection reference timings so as to perform projection a plurality of times at a fixed period, A first projection mode (normal projection mode) in which each projection reference timing is used as each projection timing for projection, and a second projection mode (shift projection mode) in which projection is performed according to each projection timing obtained by temporally shifting each projection reference timing can be set, In the second projection mode, the shift time for shifting each projection reference timing is changed by a fixed time (fixed time α) each time, and each projection reference timing is shifted to determine each projection timing. An object detection device (object detection device 1).

[0119] Accordingly, even if a plurality of object detection devices are arranged in the vicinity, the object detection device can prevent the interference state caused by the projection light projected by other object detection devices from occurring continuously, and can suppress false detection of the presence of an object.

[0120] (Item 2) The controller In the second light projection mode, for a predetermined number of shift times, shift each light projection reference timing so that the shift time changes by the fixed time each time, and after the end of the predetermined number of shift times, return the light projection timing to the light projection reference timing, and determine each light projection timing so as to repeat the shift of each light projection reference timing over the predetermined number of shift times. The object detection device according to Item 1.

[0121] Accordingly, the object detection device can prevent the change in the shift time from accumulating and the time difference between the light projection reference timing and the corrected light projection timing from becoming too long. Therefore, the object detection device can suppress a decrease in the light projection frequency of the projection light and performing object detection in a detection direction different from the originally intended detection direction.

[0122] (Item 3) The controller In the second light projection mode, shift each light projection reference timing so that the shift time increases by the fixed time each time, and determine each light projection timing. The object detection device according to Item 1 or 2.

[0123] Accordingly, the object detection device can correct the light projection timing while minimizing the temporal shift from the light projection reference timing, for example, by gradually increasing from the light projection reference timing. Therefore, the object detection device can shift the light projection timing so as to be close to the originally planned light projection timing.

[0124] (Item 4) The controller In the second light projection mode, each light projection reference timing is shifted so that the shift time decreases by the fixed time at a time, and each light projection timing is determined. The object detection device according to item 1 or 2.

[0125] Accordingly, the object detection device, for example, gradually shortens the shift time by the fixed time at a time from a timing as far as possible from the light projection reference timing after the light projection reference timing, so that it is possible to expect that the presence or absence of the received light of the projection light 3A from another object detection device can be confirmed at the light projection timing in the early stage. Therefore, it is highly possible that the object detection device can avoid receiving interference light within the longest time corresponding to the longest distance measurable by the projection light, and can reduce the possibility of false detection of an object.

[0126] (Item 5) The controller is In the second light projection mode, after shifting each light projection reference timing so that the shift time increases by the fixed time at a time, each light projection reference timing is shifted so that the shift time decreases by the fixed time at a time, and each light projection timing is determined, or after shifting each light projection reference timing so that the shift time decreases by the fixed time at a time, each light projection reference timing is shifted so that the shift time increases by the fixed time at a time, and each light projection timing is determined. The object detection device according to item 1 or 2.

[0127] Accordingly, even when the object detection device performs a plurality of consecutive increases and decreases of the fixed time of the shift time, it is possible to prevent the interference state caused by the projection light projected by another object detection device from occurring continuously, and it is possible to suppress false detection of the presence of an object.

[0128] (Item 6) The projection light is projected along a first plane (the upper or lower surface of the fixed part 100, the floor surface, the housing surface of a predetermined device), and further includes a rotating part (rotating part 300) that rotates the projection direction of the projection light along the first plane. The controller controls the rotating part to rotate at a constant speed. generates the plurality of light projection reference timings so as to perform light projection at every certain angle in the rotation by the rotating part. In the second light projection mode, at every certain angle, the shift time for shifting each light projection reference timing is changed by a certain time, and each light projection reference timing is shifted to determine each light projection timing. The object detection device according to any one of Items 1 to 5.

[0129] Thereby, when the object detection device can project light in various directions by the rotation of the rotating part and detect an object, it is possible to prevent the interference state caused by the projection light projected by another object detection device from occurring continuously, and false detection of the object can be suppressed.

[0130] (Item 7) The certain time is longer than the time (area detection setting time DT) based on the longest distance measurable by the projection light (area detection setting distance DL) and the speed of light. The object detection device according to any one of Items 1 to 6.

[0131] Thereby, even if interference occurs at the previous light projection timing, the object detection device can suppress the interference at the subsequent light projection timing. This is because it is possible to prevent the projection light projected periodically from being received within the above time (area detection setting time DT) at the subsequent light projection timing.

[0132] (Item 8) The controller acquires the clock generated by the clock generator. determines the certain period based on the clock. The object detection device according to any one of items 1 to 7.

[0133] Thereby, even if the operation of the rotation angle detector is inaccurate, the object detection device can determine a constant period.

[0134] (Item 9) Obtain the rotation angle detected by a rotation angle detector (rotation angle detector 403) that detects the rotation angle of the rotating part, Determine the constant period based on the rotation angle, The object detection device according to any one of items 1 to 7.

[0135] Thereby, even if the operation of the clock generator is inaccurate, the object detection device can determine a constant period.

[0136] (Item 10) A step of projecting projection light according to projection timing, A step of receiving the reflected light reflected by the object from the projection light and generating a reception signal, A step of generating a plurality of projection reference timings so as to project light a plurality of times at a constant period, A step of setting a projection mode, And having As the projection mode, a first projection mode in which each projection reference timing is used as each projection timing, and a second projection mode in which each projection is performed according to each projection timing obtained by temporally shifting each projection reference timing can be set, The step of setting the projection mode is When the second projection mode is set as the projection mode, the step of shifting each projection reference timing to determine each projection timing so that the shift time for shifting each projection reference timing changes by a fixed time each time. Object detection method.

[0137] Thereby, the same effect as in item 1 can be obtained.

Industrial Applicability

[0138] The present disclosure is useful for an object detection device, an object detection method, etc. that can suppress false detection of the presence of an object due to interference of projected light from another object detection device even when another object detection device is disposed opposite thereto.

Description of Reference Numerals

[0139] 1 Object detection device 3A Projected light 3B Reflected light 10 Outer cover part 11 Wavelength window 100 Fixed part 101 Substrate 102 Light-emitting element 103 Light-receiving element 104 Condensing lens 105 Collimator lens 106 Coil 107 Photointerrupter 108 Amplification circuit 109 Laser drive circuit 300 Rotating part 301 Rotating member 302 Magnet 303 Reflecting mirror 311 Rib 401 Comparator 402 Motor 403 Rotation angle detector 404 Motor drive circuit 500 TDC 600 Controller 610 Distance measurement control unit 620 Distance calculation unit 630 Rotation control unit 640 Light projection timing generation unit 650 Light projection timing correction unit

Claims

1. A light-emitting element that emits projection light according to projection timing, a light-receiving element that receives reflected light obtained by reflecting the projection light by an object and generates a light-receiving signal, and a controller, wherein the controller generates a plurality of light projection reference timings so as to perform light projection a plurality of times at a constant period, and is capable of setting a first light projection mode in which each light projection reference timing is used as each light projection timing for light projection, and a second light projection mode in which light projection is performed according to each light projection timing obtained by temporally shifting each light projection reference timing, and in the second light projection mode, each light projection reference timing is shifted to determine each light projection timing such that a shift time for shifting each light projection reference timing changes by a fixed time at a time. An object detection device.

2. The controller in the second light projection mode, shifts each light projection reference timing so that the shift time changes by the fixed time over a predetermined number of shift times, returns the light projection timing to the light projection reference timing after the end of the predetermined number of shift times, and determines each light projection timing so as to repeat the shift of each light projection reference timing over the predetermined number of shift times. The object detection device according to claim 1.

3. The controller in the second light projection mode, shifts each light projection reference timing so that the shift time increases by the fixed time at a time to determine each light projection timing. The object detection device according to claim 1 or 2.

4. The controller in the second light projection mode, shifts each light projection reference timing so that the shift time decreases by the fixed time at a time to determine each light projection timing. The object detection device according to claim 1 or 2.

5. The controller in the second light projection mode, after shifting each light projection reference timing so that the shift time increases by the fixed time at a time, shifts each light projection reference timing so that the shift time decreases by the fixed time at a time to determine each light projection timing, or after shifting each light projection reference timing so that the shift time decreases by the fixed time at a time, shifts each light projection reference timing so that the shift time increases by the fixed time at a time to determine each light projection timing. The object detection device according to claim 1 or 2.

6. The projection light is projected along a first plane, and a rotating unit that rotates the projection direction of the projection light along the first plane is further provided. The controller: controls the rotating unit to rotate at a constant speed, generates the plurality of light projection reference timings so as to perform light projection at every certain angle in the rotation by the rotating unit, In the second light projection mode, at every certain angle, the light projection timings are determined by shifting the respective light projection reference timings such that the shift time for shifting the respective light projection reference timings changes by the certain time at a time. The object detection device according to claim 1 or 2.

7. The certain time is a time longer than a time based on the longest distance measurable by the projection light and the speed of light. The object detection device according to claim 1 or 2.

8. The controller: acquires a clock generated by a clock generator, determines the certain period based on the clock. The object detection device according to claim 1 or 2.

9. acquires the rotation angle from a rotation angle detector that detects the rotation angle of the rotating unit, determines the certain period based on the rotation angle. The object detection device according to claim 6.

10. A step of projecting projection light according to a light projection timing; A step of receiving reflected light reflected by an object from the projection light and generating a reception signal; A step of generating a plurality of light projection reference timings so as to perform light projection a plurality of times at a certain period; A step of setting a light projection mode; and includes: As the light projection mode, a first light projection mode in which each light projection reference timing is used as a light projection timing for light projection and a second light projection mode in which light projection is performed according to each light projection timing obtained by temporally shifting each light projection reference timing can be set. The step of setting the light projection mode: When the second light projection mode is set as the light projection mode, includes a step of shifting the respective light projection reference timings so that the shift time for shifting the respective light projection reference timings changes by a certain time at a time, and determining the respective light projection timings. An object detection method.

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