Light projection device, object detection device, moving body, light projection method and program

Abstract

To provide a floodlight device capable of controlling floodlight.SOLUTION: A floodlight device 10 that projects light has a light source unit that emits light, and a control unit that controls a pulse width of light and a voltage applied to the light source unit. The control unit controls the pulse width and the applied voltage so that when light is projected onto a first region, an amount of projected light becomes a first light amount, and when light is projected onto a second region different from the first region, the amount of projected light becomes a second light amount different from the first light amount.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present application relates to a light projection device, an object detection device, a moving body, a light projection method, and a program. [Background technology]

[0002] Conventionally, there is known a device that has a laser light projecting device, processes a light receiving signal of return light that is reflected or scattered by an object from the projected laser light, and detects object information such as the presence or absence of an object, the distance to the object, etc. Furthermore, when it is desired to obtain longer distance information or highly accurate object information in a specific area such as the center of the light projection area, a technique is known for increasing the amount of light projected to this specific area.

[0003] Also, in order to enable long-distance light projection, a configuration has been disclosed in which a light source such as a semiconductor laser is voltage-controlled (see, for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the device of Patent Document 1, when the amount of light projected onto a specific area is increased, the stabilization time until the voltage reaches a desired voltage becomes long, and there is room for improvement in the control of light projection.

[0005] An object of the present invention is to provide a floodlight device capable of controlling light emission. [Means for solving the problem]

[0006] A light-projecting device according to one aspect of the present invention is a light-projecting device that projects light, and emits the light. Light emitting circuit including a laser diode Department and A voltage application unit and a pulse width control unit are included, and the voltage application unit and the pulse width control unit control the emission of the light by the laser diode. A control unit, a current flowing through the laser diode in response to a voltage applied to the light-emitting circuit unit by controlling the voltage applied by the voltage application unit, and a pulse width of light emitted by the light-emitting circuit unit by the pulse width control unit to control an integrated light quantity per pulse of the light emitted by the laser diode; When the light is projected onto the first region, The integral of the light When the light amount becomes a first light amount and the light is projected onto a second area different from the first area, The integral of light a second light amount different from the first light amount is controlled; The integral of lightThe amount of light reaches the first amount of light or the second amount of light. When reaching the goal Until now, In response to the passage of time, Increasing the applied voltage This increases the current flowing through the laser diode. In addition, Of light The pulse width is increased, The integral of light After the light amount reaches the first light amount or the second light amount, the applied voltage , which is greater than the applied voltage when the target is reached. As we make it bigger 、 The above Of light Pulse width , the pulse width of the light when the target is reached Make it narrower. Effect of the Invention

[0007] According to the present invention, light projection can be controlled. [Brief description of the drawings]

[0008] [Figure 1] 1 is a block diagram showing an example of the overall configuration of a LIDAR device according to a first embodiment. FIG. [Diagram 2] FIG. 2 is a block diagram showing a configuration example of a light-emitting unit. [Diagram 3] 4 is a circuit diagram illustrating an example of a function of a light emitting circuit unit. FIG. [Figure 4] 13 is a diagram showing examples of various driving waveforms, where (a) shows the DC / DC converter output voltage, (b) shows the pulse width of the light emission control unit, (c) shows the voltage applied to the light emission circuit unit, and (d) shows the current flowing through the LD. [Diagram 5] 4 is a timing chart of a first example of a control operation of the light emitting circuit unit. [Figure 6] 10 is a timing chart of a second example of the control operation of the light emitting circuit unit. [Figure 7] 13 is a timing chart of a third example of the control operation of the light emitting circuit unit. [Figure 8] 13 is a timing chart of a fourth example of the control operation of the light emitting circuit unit. [Figure 9] FIG. 4 is a diagram illustrating a light scanning range. [Figure 10] 11A and 11B are diagrams showing a first example of the control operation of the pulse width and the applied voltage according to the scanning angle. [Figure 11]11A to 11C are diagrams showing the control operation of various pulse widths and applied voltages according to the scanning angle, where (a) shows a second example, (b) shows a third example, and (c) shows a fourth example. [Figure 12] 10A to 10C are diagrams showing examples of control operations of a pulse width and an applied voltage according to a first detection scene, where (a) shows the first detection scene, (b) shows a first example, and (c) shows a second example. [Figure 13] 11A to 11C are diagrams showing examples of control operations of pulse width and applied voltage according to a second detection scene, where (a) shows the second detection scene, (b) shows the first example, and (c) shows the second example. [Figure 14] 4 is a flowchart of an operation example of the LIDAR device according to the first embodiment. [Figure 15] FIG. 11 is a diagram illustrating an example of the overall configuration of a moving body according to a second embodiment. [Figure 16] FIG. 11 is a diagram illustrating an example of the hardware configuration of a moving body according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiment of the invention will be described with reference to the drawings. In each drawing, the same components are given the same reference numerals, and duplicated explanations may be omitted. The embodiments shown below are examples of a light projecting device and an object detection device for embodying the technical idea of ​​the present invention, and the present invention is not limited to the embodiments shown below. The dimensions, materials, shapes, relative positions, etc. of the components described below are intended to be illustrative, and not to limit the scope of the present invention, unless otherwise specified. The sizes and positional relationships of the components shown in the drawings may be exaggerated to clarify the explanation.

[0010] The light projection device according to the embodiment includes a light source unit that emits light and a control unit that controls the pulse width of the light and the voltage applied to the light source unit. This light projection device is a device used by an object detection device that detects object information such as the presence or absence of an object or the distance to the object based on the return light reflected or scattered by the object when the projected light is projected. Such object detection devices include LIDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging) devices mounted on moving bodies such as vehicles.

[0011] In the embodiment, when light is projected onto the first region, the projected light amount becomes the first light amount, and when light is projected onto the second region different from the first region, the pulse width and the applied voltage are controlled so that the projected light amount becomes the second light amount different from the first light amount.

[0012] For example, the first region corresponds to a specific region, and the first light amount corresponds to a projected light amount larger than the second light amount. By controlling both the pulse width and the applied voltage, even when increasing the projected light amount to a specific region, the projected light amount can be changed at high speed and the light projection can be controlled.

[0013] Hereinafter, the embodiment will be described by taking a LIDAR device mounted on an automobile (an example of a moving body) having the light projection device according to the embodiment as an example.

[0014] [First Embodiment] [Overall Configuration Example of LIDAR Device 100]< First, referring to FIG. 1, an overall configuration example of the LIDAR device 100 according to the first embodiment will be described. FIG. 1 is a block diagram for explaining an example of the overall configuration of the LIDAR device 100.

[0015] The LIDAR device 100 is an example of an object detection device that is mounted on an automobile and detects the presence or absence of an object present in the positive X-axis direction corresponding to the moving direction of the automobile, and detects object information including the distance to the object. As shown in Fig. 1, the LIDAR device 100 has a light projecting device 10, a light receiving unit 3, a light receiving circuit 4, an A / D (Analog / Digital) conversion unit 5, a signal processing unit 6, and an area information acquisition unit 7. Each component is fixed in a housing (not shown) to constitute the LIDAR device 100. However, some of the components may be disposed outside the housing.

[0016] Of these, the light projection device 10 has a light emitting unit 1 and a scanning unit 2, and projects a scanning light of a laser beam 101 toward a light projection area 200.

[0017] The light emitting unit 1 is an example of a light source unit that emits a pulsed laser light 101. The laser light 101 is an example of light emitted by a light source unit. The wavelength of the laser light 101 is not particularly limited, but when the LIDAR device 100 is mounted on an automobile, non-visible light that cannot be seen by the naked eye, such as light with a wavelength longer than 760 nm, is preferable from the viewpoint of safety. Details of the light emitting unit 1 will be described below with reference to FIG. 2.

[0018] The scanning unit 2 is an example of an optical scanning unit that scans the laser light 101 emitted by the light emitting unit 1 in a scanning direction (Y-axis direction) that intersects with the moving direction of the automobile. This scanning direction is an example of a predetermined direction. The scanning unit 2 has a deflection element such as a MEMS (Micro Electro Mechanical System) mirror, a polygon mirror, or a galvanometer mirror, and scans the laser light 101 by changing the angle of the deflection surface of the deflection element. This enables light projection over a wide range.

[0019] The light receiving unit 3 has a light receiving element, receives return light 102 resulting from the laser light 101 being reflected or scattered by an object 201 present in the light projection area 200, and outputs a voltage signal according to the light intensity of the return light 102 to the light receiving circuit 4. The light receiving unit 3 is an example of an optical detection unit that receives return light 102 resulting from the laser light 101 projected by the light projecting device 10 being reflected or scattered by an object.

[0020] The light receiving element may be a photodiode (PD), an avalanche photodiode (APD), a single photo avalanche photodiode (SPAD) which is a Geiger mode APD, etc. The light receiving unit 3 may include optical elements such as a lens and a mirror.

[0021] The light receiving circuit 4 amplifies this voltage signal and outputs it to the A / D conversion unit 5. The light receiving circuit 4 may also include a filter or the like for cutting noise.

[0022] The A / D conversion unit 5 has an A / D converter and outputs a digital signal after A / D conversion to the signal processing unit 6. The A / D conversion unit 5 may be configured with an integrated circuit such as an FPGA (Field Programmable Gate Array) or an IC (Integrated Circuit) that adds other functions in addition to A / D conversion. Also, a function equivalent to that of the A / D conversion unit 5 can be realized by a comparator.

[0023] The signal processing unit 6 can acquire object information by calculation based on the input digital signal and output the acquired object information to an external device. In this case, the external device may be an ECU (Electronic Control Unit) of an automobile. Here, the signal processing unit 6 is an example of an output unit that outputs object information including at least one of information on the presence or absence of an object acquired based on detection information by the light receiving unit 3 and information on the distance to the object.

[0024] The area information acquisition unit 7 acquires area information indicating the position of the area in which the object 201 exists within the light projection area 200, and provides the area information to the light projection device 10. This area information acquisition unit 7 is, for example, a speedometer or a stereo camera. The area information acquisition unit 7 can also be configured by a processing circuit or the like that acquires area information based on information acquired immediately before by the signal processing unit 6.

[0025] <Configuration example of light-emitting unit 1> Next, the configuration of the light-emitting unit 1 will be described with reference to Fig. 2. Fig. 2 is a block diagram illustrating an example of the configuration of the light-emitting unit 1. As shown in Fig. 2, the light-emitting unit 1 has a control unit 11, a light-emitting circuit unit 12, and a temperature detection unit 13. Each component is mounted on an electric board or the like to form the light-emitting unit 1.

[0026] The control unit 11 has a DC / DC (Direct Current / Direct Current) converter 111 and a light emission control unit 112 , and controls the pulse width of the light emitted by the light emission circuit unit 12 and the voltage applied to the light emission circuit unit 12 .

[0027] The DC / DC converter 111 is an example of a voltage application unit that converts a voltage input from an external power supply into a voltage of a predetermined value and generates a voltage to be applied to the light-emitting circuit unit 12. For example, the DC / DC converter 111 can convert a voltage of 5 [V], 12 [V], 24 [V], or the like output from the external power supply into a voltage ranging from 5 [V] to 100 [V] to generate a voltage to be applied. An example of the external power supply is a battery provided in an automobile in which the LIDAR device 100 is mounted.

[0028] The light emission control unit 112 is configured to include an FPGA or an SoC (System on a Chip), etc. The light emission control unit 112 is an example of a pulse width control unit that controls the pulse width of light emitted by the light emission circuit unit 12 by switching-driving the LD drive switch 122 at a desired timing.

[0029] The light-emitting circuit section 12 has an LD (Laser Diode) 121 and an LD drive switch 122, and is an example of a light source section that emits laser light 101 (see FIG. 1).

[0030] The LD 121 is a light source that emits the laser light 101. Note that instead of the LD, a vertical cavity surface emitting laser (VCSEL) or a light emitting diode (LED) may be used.

[0031] The LD drive switch 122 is a switching circuit that switches between emission (on) and non-emission (off) of the laser light 101 by the LD 121, and is an example of a switching unit. In the embodiment, the LD drive switch 122 includes a GaN (gallium nitride) FET. However, it may also be configured to include a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) or other transistors.

[0032] The temperature detection unit 13 includes a temperature sensor such as a thermocouple that detects the temperature of the light emitting unit 1 and / or the surroundings of the light emitting unit 1. Since the IV characteristics and IL characteristics of the LD 121 may change depending on the temperature of the light emitting unit 1, the LD 121 can be controlled based on the detection value by the temperature detection unit 13.

[0033] In addition to the above configuration, the light emitting unit 1 may also include optical elements such as lenses and mirrors, a spectroscope that separates the projected laser light, and a light quantity meter that measures the quantity of the projected laser light.

[0034] <Example of detailed functions of the light emission circuit section 12> Next, the function of the light-emitting circuit unit 12 in the light-emitting unit 1 will be described in detail with reference to Fig. 3. Fig. 3 is a circuit diagram illustrating an example of the function of the light-emitting circuit unit 12. As shown in Fig. 3, a resistor R, an inductance L, an LD 121, and an LD drive switch 122 are connected in series to configure the light-emitting circuit unit 12.

[0035] Here, the current I flowing through the light-emitting circuit section 12 can be expressed by the following formula (1).

[0036]

number

[0037] The amount of light of the projected laser light 101 is proportional to the current I, and can be expressed as the following equation (2) using a proportionality coefficient η.

[0038]

number

[0039] In addition, as can be seen from formula (1), by controlling the voltage applied to the light-emitting circuit unit 12, it is possible to control the amount of light emitted by the LD 121 without directly controlling the voltage of the LD 121.

[0040] Generally, the time it takes for a DC / DC converter to stabilize is on the scale of milliseconds to seconds, and voltage control alone requires a time on the scale of milliseconds to seconds until the light intensity of the light source stabilizes. On the other hand, even when the on-time of the light source is extended, the maximum current is Vop-Vld / R, so the current dynamic range is narrow.

[0041] In contrast, in the embodiment, the amount of laser light can be controlled by both the time t corresponding to the pulse width and the voltage V corresponding to the applied voltage, as in formula (2). Therefore, even when increasing the amount of light projected onto a specific area, the light-emitting circuit unit 12 is capable of controlling light projection so as to change the amount of light projected onto the specific area at high speed and project light onto the specific area at high speed.

[0042] Next, the drive waveforms of each component of the light-emitting unit 1 will be described with reference to Fig. 4. Fig. 4 is a timing chart showing an example of various drive waveforms. (a) shows the output voltage of the DC / DC converter 111, (b) shows the pulse width by the light-emitting control unit 112, (c) shows the voltage applied to the light-emitting circuit unit 12, and (d) shows the current flowing through the LD 121. Note that since the current flowing through the LD 121 is proportional to the amount of laser light emitted by the LD 121, Fig. 4(d) also corresponds to the amount of light emitted.

[0043] Since the stabilization time of the DC / DC converter 111 is long, the DC / DC converter 111 increases the output voltage in stages over separate periods, as shown in Fig. 4(a). The voltage applied to the light-emitting circuit unit 12 increases as the output voltage increases. Furthermore, according to the period during which the DC / DC converter 111 increases the output voltage, the light-emitting control unit 112 controls the pulse width to become wider, as shown in Fig. 4(b).

[0044] In the light-emitting circuit unit 12, the voltage application time becomes longer and the voltage value becomes larger as shown in Fig. 4(c) according to the output voltage of the DC / DC converter 111 and the pulse width by the light-emitting control unit 112. Also, in response to the voltage applied to the light-emitting circuit unit 12, the amount of current flowing through the LD 121 increases and the period during which the current flows through the LD 121 becomes longer as shown in Fig. 4(d).

[0045] In this way, the control unit 11 uses the DC / DC converter 111 and the light emission control unit 112 to control the pulse width of the laser light emitted by the LD 121 and the voltage applied to the light emission circuit unit 12, thereby controlling the amount of light projection.

[0046] <Example of control operation of the light-emitting circuit section 12> Next, an example of the control operation of the light emitting circuit unit 12 will be described with reference to Fig. 5 to Fig. 8. Here, in the LIDAR device, in order to properly detect object information, it may be necessary to optimize the amount of light projected by the laser light according to the detection scene. Fig. 5 to Fig. 8 show examples of the control operation of the LD 121 according to various detection scenes. The description will also be given with reference to the configuration diagram of Fig. 3 as appropriate.

[0047] (Example 1) 5 is a timing chart for explaining a first example of the control operation of the light-emitting circuit unit 12. The first example is an example of the control operation of the light-emitting circuit unit 12 when it is desired to suddenly change the current flowing through the LD 121. More specifically, this is the case when the road on which the automobile carrying the LIDAR device 100 is traveling changes from an urban road to an expressway.

[0048] For example, in urban areas, it is sufficient to mainly detect information on objects located close to the vehicle, such as oncoming vehicles, pedestrians, and bicycles. On the other hand, on expressways, it is preferable to also detect information on objects located far away, such as a preceding vehicle traveling ahead of the vehicle. Therefore, when the road changes from an urban road to an expressway, it is preferable to suddenly increase the current flowing through the LD 121 to increase the amount of light projected, so that information on objects located far away can be detected immediately.

[0049] 5 is a timing chart showing the output voltage of the DC / DC converter 111, the middle one the pulse width by the light emission control unit 112, and the bottom one the current flowing through the LD 121. The graph in the bottom also corresponds to the amount of projected laser light.

[0050] 5, the light emission control unit 112 widens the pulse width in accordance with the output voltage of the DC / DC converter 111. This increases the voltage value applied to the light emission circuit unit 12 and lengthens the application time, thereby enabling control to increase the amount of projected light at high speed compared to the case where only the output voltage of the DC / DC converter 111 is controlled.

[0051] (Example 2) Next, Fig. 6 is a timing chart for explaining a second example of the control operation of the light-emitting circuit section 12. The way to read the figure is the same as Fig. 5, but compared to Fig. 5, a graph showing the number of times light is emitted per unit time is added at the bottom.

[0052] The second example is a control operation of the light-emitting circuit unit 12 when it is desired to keep the current flowing through the LD 121 constant for each of a plurality of operation modes. In Fig. 6, a normal operation mode A and an operation mode B for reducing power consumption are shown as the plurality of operation modes. In operation mode B, the output voltage of the DC / DC converter 111 is reduced and the pulse width by the light-emitting control unit 112 is narrowed, thereby suppressing the current flowing through the LD 121 and suppressing power consumption. It is also possible to improve the angular resolution by increasing the number of emissions per unit time while suppressing power consumption.

[0053] 6, in operation mode B, the output voltage of the DC / DC converter 111 is smaller and the pulse width by the light emission control unit 112 is narrower than in operation mode A. This reduces the current flowing through the LD 121, suppressing power consumption. Note that during the operation period in each operation mode, the current flowing through the LD 121 is constant.

[0054] (Example 3) Next, Fig. 7 is a timing chart of a third example of the LD control operation. The diagram can be read in the same way as Fig. 5. The third example is a control operation in which the change in the output voltage of the DC / DC converter 111 is assisted by the pulse width of the light emission control unit 112 when the output voltage of the DC / DC converter 111 fluctuates due to the influence of temperature fluctuations and the like, and there is a possibility that the amount of projected light may deviate from the target value.

[0055] 7, the light emission control unit 112 gradually narrows the pulse width in response to an increase in the output voltage of the DC / DC converter 111 accompanying an increase in temperature. As a result, the current flowing through the LD 121 becomes almost equal to the target value and is constant.

[0056] (Example 4) Fig. 8 is a timing chart of a fourth example of the control operation of the light-emitting circuit unit 12. The diagram can be read in the same way as in Fig. 5. The fourth example is a control operation in which the current flowing through the LD 121 is rapidly increased, the amount of projected light reaches a target value, and then the output voltage of the DC / DC converter 111 is further increased and the pulse width is narrowed conversely. Since there is a concern that power consumption will increase when the pulse width is wide, the pulse width is narrowed after the amount of projected light reaches a target value and the output voltage of the DC / DC converter 111 is increased, thereby making it possible to suppress power consumption while keeping the amount of projected light constant.

[0057] 8, until the amount of projected light reaches the target value, the output voltage of DC / DC converter 111 is increased and the pulse width by light emission control unit 112 is widened. After the amount of projected light reaches the target value, the output voltage of DC / DC converter 111 is increased, but the pulse width by light emission control unit 112 is narrowed. This suppresses power consumption while maintaining the amount of projected light at the target value.

[0058] <Example of control operation according to scanning angle> Next, a control operation of the applied voltage and pulse width control operation according to the scanning angle by the scanning unit 2 (see FIG. 1) will be described.

[0059] First, Fig. 9 is a diagram for explaining an example of an optical scanning range by the scanning unit 2. Fig. 9 shows how the LIDAR device 100 projects the laser light 101 in the positive direction of the X-axis corresponding to the movement direction while scanning with the laser light 101 in a scanning direction along the Y-axis direction. The direction along the movement direction corresponds to the direction of a scan angle of 0 degrees, and the LIDAR device 100 scans with the laser light 101 in a scanning range from +α degrees to -α degrees.

[0060] In the embodiment, an area corresponding to a predetermined angle such as 0 degrees of scanning angle is set as the attention area, and the light amount of the laser light 101 is increased to enable detection of object information even for objects at a long distance. This attention area corresponds to a specific area and is an example of a first area. The light amount of the laser light 101 increased in the attention area is an example of a first light amount. Moreover, an area other than the attention area within the scanning range is an example of a second area. The light amount of the laser light 101 projected to this second area and smaller than the first light amount in the attention area is an example of the second light. Various control operation examples of the pulse width and applied voltage according to the scanning angle will be described below.

[0061] (Example 1) Fig. 10 is a diagram for explaining a first example of the control operation of the pulse width and applied voltage according to the scan angle. In Fig. 10, as in Fig. 9, the positive X-axis direction corresponds to the moving direction of the car, and the Y-axis direction corresponds to the scanning direction of the laser light. The direction along the moving direction corresponds to the direction of the scan angle of 0 degrees, and the range from +α degrees to -α degrees is the scanning range of the laser light.

[0062] The dashed line indicates the pulse width 103, which is a graph showing the pulse width of the laser light for each scanning angle. The solid line indicates the applied voltage 104, which is a graph showing the applied voltage to the light-emitting circuit unit 12 for each scanning angle. In these graphs, the more positive the X-axis, the wider the pulse width 103 and the larger the applied voltage 104.

[0063] In the example of FIG. 10, the region of interest is an area corresponding to a scanning angle of 0 degrees. At a scanning angle of 0 degrees, the LIDAR device 100 widens the pulse width 103 and increases the applied voltage 104. By controlling both the pulse width 103 and the applied voltage 104, the amount of projected light can be controlled at high speed and the amount of projected light in the region of interest can be increased at high speed. In other words, the LIDAR device 100 controls both the pulse width 103 and the applied voltage 104 according to the region to which the laser light 101 is projected, thereby changing the waveform of the voltage applied to the light emission circuit unit 12 and enabling the amount of projected light to be controlled at high speed.

[0064] (2nd to 4th cases) 11A, 11B, and 11C are diagrams for explaining the control operation of various pulse widths and applied voltages according to the scanning angle, where (a) shows a second example, (b) shows a third example, and (c) shows a fourth example.

[0065] 11(a) to 11(c) can be viewed in the same manner as in FIG. 9, but in order to simplify the drawing, the LIDAR device 100 and the scanning angles α and −α are omitted in FIG.

[0066] 11(a) shows the control operation when the region of interest is set to an area corresponding to a scan angle of 0 degrees, the pulse width 103 is narrowed at a scan angle of 0 degrees, and the applied voltage 104 is increased. Compared to when the pulse width is widened together with the applied voltage, the control width for the amount of projected light is narrowed, but by narrowing the pulse width, it is possible to reduce the temporal variation in object detection.

[0067] Figures 11(b) and (c) show the control operation when the region of interest is set to a region other than the region corresponding to a scan angle of 0 degrees. In Figure 11(b), pulse width 103 is narrowed at the scan angle corresponding to the region of interest, and applied voltage 104 is increased. In Figure 11(c), pulse width 103 is widened at the scan angle corresponding to the region of interest, and applied voltage 104 is increased.

[0068] <Examples of control operations according to detected scenes> Next, the control operation of the pulse width and applied voltage according to various detection scenes by the LIDAR device will be described.

[0069] (Example of control operation in the first detection scene) 12 is a diagram for explaining an example of the control operation of the pulse width and the applied voltage according to the first detection scene. (a) shows the first detection scene, (b) shows the first example, and (c) shows the second example. Note that the way to view (b) and (c) of FIG. 12 is the same as FIG. 11.

[0070] Fig. 12(a) shows a state where a vehicle 300 equipped with a LIDAR device travels in an urban area in the positive direction of the X-axis, as indicated by an arrow 301, and then turns left in the negative direction of the Y-axis at an intersection. In the vicinity of the intersection, objects such as pedestrians 202, a preceding vehicle 203, and an oncoming vehicle 204 are scattered over a wide area. Therefore, it is preferable to project laser light with the same light projection amount over a wide scanning angle. As shown in Fig. 12(b), control is performed so that light is projected with the same pulse width 103 and applied voltage 104 regardless of the scanning angle.

[0071] Furthermore, as shown in FIG. 12(a), when the vehicle 300 turns left at an intersection and a pedestrian 202 is present, it is desirable to set the pedestrian 202 as a target area (target object) and accurately detect the distance to the pedestrian 202.

[0072] When the pedestrian 202 is present in the area corresponding to the scanning angle β, the pulse width 103 and the applied voltage 104 are controlled so that the amount of projected light is increased at the scanning angle β, as shown in Fig. 12(c). Because both the pulse width 103 and the applied voltage 104 are controlled, the amount of projected light can be increased at higher speeds, and the system can be quickly switched to a state in which the distance to the pedestrian 202 can be accurately detected even in rapidly changing conditions while driving. After the host vehicle 300 passes near the pedestrian 202, the control returns to the state in Fig. 12(b).

[0073] (Example of control operation in the second detection scene) 13 is a diagram for explaining an example of the control operation of the pulse width and the applied voltage according to the second detection scene. (a) shows the second detection scene, (b) shows the first example, and (c) shows the second example. The way to view (b) and (c) of FIG. 13 is the same as FIG. 11.

[0074] In Fig. 13(a), a vehicle 300a equipped with a LIDAR device is shown traveling on a highway in the positive direction of the X-axis. Since the vehicle speed is high on the highway, it is necessary to detect objects that are far away. In addition, since there are no pedestrians on the highway, it is sufficient to perform detection within a narrow range, such as the range corresponding to the width of the road on which the vehicle is traveling, as shown in Fig. 13(b).

[0075] As shown in Fig. 13(a), when the host vehicle 300a attempts to change lanes in the direction of arrow 301 and move to the position of the host vehicle 300b, if the preceding vehicle 205 is present in the right lane, it is desired to accurately detect the distance to the preceding vehicle 205 with the preceding vehicle 205 as the attention area (attention object).

[0076] When the preceding vehicle 205 is present in the area corresponding to the scanning angle γ, as shown in Fig. 13(c), the pulse width 103 and the applied voltage 104 are controlled so that the light emission amount increases at the scanning angle γ. In order to control both the pulse width 103 and the applied voltage 104, the light emission amount can be increased at a higher speed, and it can be quickly switched to a state where the distance to the preceding vehicle 205 can be accurately detected. After the host vehicle 300b changes lanes and ends, such as when moving to the position of the host vehicle 300c, the operation returns to the state of Fig. 13(b).

[0077] Although two detection scenes, the first detection scene and the second detection scene, are exemplified, the present invention is not limited thereto, and the LIDAR device 100 can correspond to various detection scenes.

[0078] <Example of control operation of LIDAR device 100> Next, with reference to Fig. 14, the operation of the LIDAR device 100 will be described. Fig. 14 is a flowchart showing an example of the operation of the LIDAR device 100. In Fig. 14, the start of the detection operation by the LIDAR device 100 is used as a trigger. The description will be made while appropriately referring to Figs. 1 and 2 as well.

[0079] First, in step S141, the area information acquisition unit 7 acquires area information in front of the moving direction of the automobile on which the LIDAR device 100 is mounted and provides it to the light emission device 10.

[0080] For example, the surrounding situation is acquired using surrounding distance data previously acquired by the LIDAR device 100, or a distance data group which is a collection of distance data, or measurement data by a distance measuring device capable of acquiring distance data directly or indirectly. In addition, in the case of a car, the surrounding situation may be acquired based on position information or map information by a GPS (Global Positioning System), and in the case of an unmanned vehicle, the surrounding situation may be acquired based on layout information such as an interior layout diagram or the presence or absence of transported goods in a warehouse.

[0081] Next, in step S142, the floodlight device 10 selects a light projection mode. The light projection mode is a light projection mode according to the position of the host vehicle, such as the host vehicles 300a, 300b, and 300c shown in Fig. 13(a), and is determined in advance.

[0082] Next, in step S143, the light projection device 10 detects the scanning angle of the scanning unit 2 and prepares for light projection. The scanning angle can be detected based on the elapsed time from the scanning origin, for example.

[0083] The order of the operations in steps S141 to S143 may be changed as appropriate, or these operations may be performed in parallel.

[0084] Next, in step S144, the light projection device 10 sets the pulse width of the laser light 101 to be projected and the voltage to be applied to the light emission circuit unit 12 based on the area information acquired in step S141 or the light projection mode selected in step S142.

[0085] Next, in step S145, the light projecting device 10 projects the laser light 101.

[0086] Next, in step S146, the light receiving unit 3 receives the return light 102 and outputs a voltage signal according to the optical intensity of the return light 102 to the light receiving circuit 4. The light receiving circuit 4 amplifies the voltage signal and outputs it to the A / D conversion unit 5, and the A / D conversion unit 5 outputs a digital signal after A / D conversion to the signal processing unit 6. The signal processing unit 6 outputs object information acquired by calculation based on the input digital signal.

[0087] Next, in step S147, the LIDAR device 100 determines whether or not one scan has been completed.

[0088] If it is determined in step S147 that the detection operation has not ended (step S147, No), the LIDAR device 100 returns to the operation in step S143 and performs the operations from step S143 onwards again. On the other hand, if it is determined in step S147 that the detection operation has ended (step S147, Yes), the LIDAR device 100 determines in step S148 whether or not to end the detection operation.

[0089] If it is determined in step S148 that the operation should not end (step S148, No), the LIDAR device 100 returns to step S141 and performs the operations from step S141 onwards again. On the other hand, if it is determined in step S148 that the operation should end (step S148, Yes), the LIDAR device 100 ends the operation.

[0090] In this manner, the LIDAR device 100 can detect object information.

[0091] <Functions and Effects of the Light Flooding Device 10> Next, the effects of the floodlight device 10 will be described.

[0092] In recent years, there has been active development of devices that project laser light, receive the return light reflected or scattered by the object, and detect object information based on the time difference between the light projection and the light reception. In such devices, the greater the amount of laser light projected, the longer the detection distance becomes.

[0093] In addition, a technology is known in which an LD is used in a light-projecting device that projects laser light, and when it is desired to detect longer distance information or highly accurate object information in a specific area, the amount of light projected onto the specific area is increased.

[0094] There are two types of LD control methods: current control and voltage control. When a large amount of light is required, such as in a LIDAR device, the voltage control method is often used. As a method for emitting a large amount of laser light using the voltage control method, a method is known in which the charge in a charged capacitor is released all at once when the LD is driven. This method only controls the charge release timing, so it is not possible to change the waveform of the laser, such as the pulse width.

[0095] In response to this, with the emergence of high-speed switching elements such as GaN FETs, a control method for LDs has been developed that emits a large amount of laser light by switching the switch on and off.

[0096] However, in the conventional control method, when the amount of light projected in a specific area is increased, the stabilization time until the applied voltage reaches a desired voltage becomes long, and there is room for improvement in the light projection control.

[0097] In this embodiment, the pulse width and applied voltage are controlled so that when laser light is projected onto a first area, the amount of projected light becomes a first amount of light, and when laser light is projected onto a second area different from the first area, the amount of projected light becomes a second amount of light different from the first amount of light.

[0098] For example, when the laser light is projected onto the first region, the applied voltage is increased and the pulse width is made wider compared to when the laser light is projected onto the second region, or, when the laser light is projected onto the first region, the applied voltage is decreased and the pulse width is made narrower compared to when the laser light is projected onto the second region.

[0099] In this way, by controlling both the pulse width and the applied voltage, the amount of light projected can be increased without waiting for the applied voltage to reach the desired voltage, so that even when the amount of light projected onto a specific area is to be increased, the amount of light projected can be changed at high speed, enabling light projection control.

[0100] In this embodiment, the waveform of the applied voltage is changed depending on the area where the laser light is projected, so that a larger amount of laser light can be projected onto a specific area such as a target area than onto other areas, and long-distance information and highly accurate object information can be obtained in the specific area.

[0101] In this embodiment, the first region is the central region of the region where the light can be projected by the light projecting device. For example, by projecting a larger amount of laser light onto this first region than onto other regions, it becomes possible to detect information on an object located far ahead of the vehicle on a highway or the like.

[0102] In the present embodiment, the optical scanning unit scans the laser beam in a predetermined direction, and projects the scanned beam from the optical scanning unit. This allows the laser beam to be projected over a wider range, making it possible to detect object information over a wider range. The predetermined direction is, for example, a direction parallel to the horizontal plane in the traveling direction of the moving body.

[0103] In this embodiment, the light source unit includes a switching unit having GaN, and the control unit controls the pulse width using the switching unit. The switching unit having GaN has a small time constant, so that the rise time is short. This allows the amount of laser light to be controlled by controlling the pulse width even during the rise.

[0104] In the present embodiment, area information about the object is acquired, and the first area is determined based on the acquired area information. This allows the first area, such as a focus area, to be determined according to the situation around the object, and the light source unit to be appropriately controlled.

[0105] [Second embodiment] Next, a moving body according to a second embodiment will be described.

[0106] Fig. 15 is a diagram showing an example of the configuration of a moving body 400 equipped with a LIDAR device 100. The moving body 400 is an automated guided vehicle that automatically transports luggage to a destination. In Fig. 15, the Z-axis direction indicates the moving direction of the moving body 400, the X-axis direction indicates a predetermined direction in a plane perpendicular to the Z-axis, and the Y-axis direction indicates a direction perpendicular to the X-axis in the plane perpendicular to the Z-axis.

[0107] The LIDAR device 100 is attached to the front (positive Z-axis direction) of the moving body 400, and acquires object information such as a range image on the positive Z-axis direction side of the moving body 400. Object information such as an obstacle on the positive Z-axis direction side of the moving body 400 can be detected by the output of the LIDAR device 100.

[0108] Next, Fig. 16 is a block diagram showing an example of a hardware configuration of a moving body 400. As shown in Fig. 16, the moving body 400 has a LIDAR device 100, a display device 30, a position control device 40, a memory 50, and a voice / alarm generating device 60. These are electrically connected via a bus 70 capable of transmitting signals and data.

[0109] In this embodiment, a travel management device 401 is configured by the LIDAR device 100, the display device 30, the position control device 40, the memory 50, and the voice / alarm generating device 60. The travel management device 401 is mounted on a moving body 400. The travel management device 401 is also electrically connected to a main controller 80 of the moving body 400.

[0110] The display device 30 is a display such as an LCD (Liquid Crystal Display) that displays object information acquired by the LIDAR device 100 and various setting information related to the moving body 400. The position control device 40 is a calculation device such as a CPU that controls the position of the moving body 400 based on the object information acquired by the LIDAR device 100. The voice / alarm generation device 60 is a device such as a speaker that determines whether an obstacle can be avoided based on the object information acquired by the LIDAR device 100 and notifies surrounding personnel when it is determined that the obstacle cannot be avoided.

[0111] In this manner, a mobile body having the LIDAR device 100 can be provided.

[0112] The moving body equipped with the LIDAR device 100 is not limited to an automatic guided vehicle. It can also be mounted on a vehicle such as an automobile, or an aircraft such as a drone. In addition to the moving body, it can also be mounted on an information terminal such as a smartphone or a tablet.

[0113] Effects other than those mentioned above are similar to those described in the first embodiment, so a duplicated description will be omitted here.

[0114] Although the embodiments have been described above, the present invention is not limited to the above specifically disclosed embodiments, and various modifications and changes are possible without departing from the scope of the claims.

[0115] The light projected by the LIDAR device 100 is not limited to laser light, and may be light with no directivity. Also, electromagnetic waves with long wavelengths, such as radar, may be used.

[0116] The embodiment also includes a light projection method. For example, the light projection method is a light projection method using a light projection device that projects light, and includes a step of emitting light from a light source unit and a step of controlling a pulse width of the light and an applied voltage to the light source unit, and in the controlling step, the pulse width and the applied voltage are controlled so that when the light is projected onto a first region, the projected light amount becomes a first light amount, and when the light is projected onto a second region different from the first region, the projected light amount becomes a second light amount different from the first light amount. Such a light projection method can provide the same effect as the above-mentioned light projection device.

[0117] The embodiment also includes a program. For example, the program causes a computer to execute a process of controlling a pulse width of light emitted by a light source unit and a voltage applied to the light source unit, and in the control process, causes the computer to execute a process of controlling the pulse width and the applied voltage so that when the light is projected onto a first area, the projected light amount becomes a first light amount, and when the light is projected onto a second area different from the first area, the projected light amount becomes a second light amount different from the first light amount. Such a program can provide the same effect as the above-mentioned light projecting device.

[0118] In addition, all numbers such as ordinal numbers and quantities used in the description of the embodiments are provided as examples to specifically explain the technology of the present invention, and the present invention is not limited to the exemplified numbers. In addition, the connection relationships between the components are provided as examples to specifically explain the technology of the present invention, and the connection relationships that realize the functions of the present invention are not limited to these.

[0119] In addition, the division of blocks in the functional block diagram is an example, and multiple blocks may be realized as one block, one block may be divided into multiple blocks, and / or some functions may be transferred to another block. Furthermore, the functions of multiple blocks having similar functions may be processed in parallel or in a time-division manner by a single piece of hardware or software. [Explanation of symbols]

[0120] 1 Light emitting unit 2 Scanning section 3. Light receiving unit (example of light detection unit) 4. Photoreceiver circuit 5 A / D conversion section 6 Signal processing section (an example of an output section) 7 Area information acquisition unit 10. Floodlight 11 Control section 111 DC / DC converter (an example of a voltage application unit) 112 Light emission control unit (an example of a pulse width control unit) 12 Light emitting circuit section (example of light source section) 121LD 122 LD drive switch 13 Temperature detection section 100 LIDAR device (an example of an object detection device) 101 Laser light 102 Return light 103 Pulse Width 104 Applied voltage 200 Light projection area 201 Object [Prior art documents] [Patent documents]

[0121] [Patent Document 1] JP 2019-027783 A

Claims

1. A light-projecting device that projects light, a light emitting circuit section including a laser diode that emits the light; a control unit including a voltage application unit and a pulse width control unit, and controlling the emission of the light by the laser diode; The control unit is a current flowing through the laser diode in response to a voltage applied to the light-emitting circuit unit by the voltage application unit is controlled, and a pulse width of light emitted by the light-emitting circuit unit is controlled by the pulse width control unit to control an integrated light quantity per pulse of the light emitted by the laser diode; controlling the integrated light quantity of the light to be a first light quantity when the light is projected onto a first region, and to be a second light quantity different from the first light quantity when the light is projected onto a second region different from the first region; until the integrated light amount of the light reaches the first light amount or the second light amount, the applied voltage is increased to increase the current flowing through the laser diode and the pulse width of the light is widened in response to the passage of time; After the integrated light amount of the light reaches the first light amount or the second light amount, the applied voltage is made larger than the applied voltage when the target is reached, and the pulse width of the light is made narrower than the pulse width of the light when the target is reached. Floodlight.

2. The control unit changes a waveform of the applied voltage depending on the area onto which the light is projected.

2. The light projecting device according to claim 1.

3. The first region is a central region in a region where light can be projected by the light projecting device.

3. The floodlight device according to claim 1 or 2.

4. a light scanning unit that scans the light in a predetermined direction; The optical scanning unit projects a scanning light.

4. The light projecting device according to claim 1.

5. the light-emitting circuit unit includes a switching unit having GaN, The control unit controls the pulse width of the light by using the switching unit.

5. A light projecting device according to claim 1.

6. the light emitting circuit unit has one laser diode drive switch that switches between emitting and not emitting the light by the laser diode, The control unit controls the operation of the laser diode drive switch to control the pulse width of the light.

6. A floodlight device according to claim 1.

7. A light projecting device according to any one of claims 1 to 6, a light detection unit that receives return light that is the light projected by the light projecting device and reflected or scattered by an object; and an output unit that outputs object information including at least one of information on the presence or absence of the object and information on the distance to the object, the information being acquired based on the detection information by the light detection unit. Object detection device.

8. a region information acquisition unit that acquires region information about the object, The control unit determines the first region based on the region information. The object detection device according to claim 7.

9. The object detection device according to claim 7 or 8, Detecting the object information in the first area or the second area in a horizontal plane in the traveling direction. Mobile body.

10. The projection of light in the first area or the second area is changed according to the movement of the moving body based on at least one of position information, map information, and arrangement information of the object. The moving body according to claim 9.

11. A light projection method using a light projection device that projects light, comprising the steps of: Emitting light from the laser diode by a light emitting circuit unit; a step of controlling the emission of the light from the laser diode by a control unit including a voltage application unit and a pulse width control unit; The control unit is a current flowing through the laser diode in response to a voltage applied to the light-emitting circuit unit by the voltage application unit is controlled, and a pulse width of light emitted by the light-emitting circuit unit is controlled by the pulse width control unit to control an integrated light quantity per pulse of the light emitted by the laser diode; controlling the integrated light quantity of the light to be a first light quantity when the light is projected onto a first region, and to be a second light quantity different from the first light quantity when the light is projected onto a second region different from the first region; until the integrated light amount of the light reaches the first light amount or the second light amount, the applied voltage is increased to increase the current flowing through the laser diode and the pulse width of the light is widened in response to the passage of time; After the integrated light amount of the light reaches the first light amount or the second light amount, the applied voltage is made larger than the applied voltage when the target is reached, and the pulse width of the light is made narrower than the pulse width of the light when the target is reached. Light projection method.

12. A program that operates in a light-projecting device that projects light, A light emitting circuit unit causes a laser diode to emit the light, a control unit including a voltage application unit and a pulse width control unit controls emission of the light by the laser diode; The control unit: a current flowing through the laser diode in response to a voltage applied to the light-emitting circuit unit by the voltage application unit is controlled, and a pulse width of light emitted by the light-emitting circuit unit is controlled by the pulse width control unit to control an integrated light quantity per pulse of the light emitted by the laser diode; controlling the integrated light quantity of the light to be a first light quantity when the light is projected onto a first region, and to be a second light quantity different from the first light quantity when the light is projected onto a second region different from the first region; until the integrated light amount of the light reaches the first light amount or the second light amount, the applied voltage is increased to increase the current flowing through the laser diode and the pulse width of the light is widened in response to the passage of time; After the integrated light amount of the light reaches the first light amount or the second light amount, the applied voltage is made larger than the applied voltage when the target is reached, and the pulse width of the light is made narrower than the pulse width of the light when the target is reached. Making a computer carry out a process program.

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