Lighting control device

Abstract

To provide a lighting control device that enables appropriate lighting control. [Solution] The lighting control device 1, which controls the lighting mode of a lighting device configured to irradiate light toward the road surface, comprises a camera 20 and a control unit 10 that controls the lighting mode based on the captured image. The camera is configured to take pictures in two shooting modes: a first exposure mode and a second exposure mode in which the exposure amount is greater than that of the first exposure mode. The control unit acquires a first mode image, which is an image taken in the first exposure mode, and a second mode image, which is an image taken in the second exposure mode, respectively. Based on the first mode image and the second mode image, it determines whether or not there is a moving object within the shooting range and is configured to switch the lighting mode depending on whether or not it has been determined that there is a moving object.

Description

Technical Field

[0001] The disclosure in this specification relates to a lighting control device.

Background Art

[0002] Patent Document 1 discloses a system for controlling the lighting state of indoor lighting. The system controls lighting by detecting the presence or absence of people using a human presence sensor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In streetlights, when there are no pedestrians or the like, a configuration for reducing the light emission amount for power saving is being considered. In addition, in the lighting control of streetlights, in order to be able to detect more diverse objects, instead of a human presence sensor, a configuration for detecting an object from a captured image taken by a camera is conceivable. At this time, in a dark situation where the light emission amount is suppressed for power saving, depending on the exposure amount of the camera, the objects that can be detected from the captured image can change. For example, from a captured image when the exposure amount of the camera is low, a vehicle with its headlights on is easy to detect, but it is difficult to detect a pedestrian. On the other hand, from a captured image when the exposure value of the camera is large, a pedestrian is easy to detect, but it is difficult to detect a vehicle with headlights. Thus, depending on the setting of the exposure amount of the camera, there is a problem that an object cannot be detected based on the captured image and the lighting of the lighting device cannot be appropriately controlled.

[0005] One object of the disclosure is to provide a lighting control device that enables appropriate lighting control.

Means for Solving the Problems

[0006] The lighting control device disclosed herein is a lighting control device that controls the lighting mode of a lighting device configured to irradiate light toward a road surface, A camera (20) is installed so as to include the road surface in its shooting range, The system includes a control unit (10) that acquires a captured image from a camera and controls the lighting mode of the lighting device based on the captured image, The camera is configured to shoot in two modes: a first exposure mode and a second exposure mode that provides a greater exposure than the first exposure mode. The control unit is The camera acquires a first-mode image, which is an image taken in the first exposure mode, and a second-mode image, which is an image taken in the second exposure mode. Based on the first mode image and the second mode image, it is determined whether or not there is a moving object within the shooting range. The system is configured to switch the lighting mode depending on whether or not it detects the presence of a moving object.

[0007] According to this disclosure, the presence or absence of a moving object is determined from images captured using two different shooting modes with different exposure levels. As a result, the control unit can expect to detect a moving object from images captured using one shooting mode, even if it cannot detect one from images captured using the other shooting mode. In other words, the risk of failing to detect a moving object can be reduced. Therefore, the lighting mode of the lighting device can be appropriately controlled. [Brief explanation of the drawing]

[0008] [Figure 1] This is a diagram showing the overall structure of the lighting control system. [Figure 2] This flowchart shows an example of processing performed by a camera. [Figure 3] This flowchart shows an example of processing performed by the control unit. [Figure 4] This flowchart shows an example of processing performed by the control unit. [Figure 5]This is a diagram showing the overall structure of the lighting control system. [Figure 6] This flowchart shows an example of processing performed by the control unit. [Figure 7] This flowchart shows an example of processing performed by the control unit. [Modes for carrying out the invention]

[0009] <First Embodiment> The embodiments of this disclosure will be described below with reference to the figures. Figure 1 is a diagram showing an example of a schematic configuration of a lighting control system 100 including a lighting control device 1. The lighting control system 100 may also be referred to as a street light control system.

[0010] The lighting control device 1 is a device that controls the lighting mode of a lighting device 3 that is configured to emit light toward the road surface. The lighting control device 1 is installed, for example, on a streetlamp. The lighting device 3 that the lighting control device 1 controls is a light source that makes up a streetlamp. The streetlamp may be configured to include, for example, a light source and a support pole. The lighting control device 1 of this embodiment may be applied to streetlamps installed around intersections. The lighting control device 1 may be applied to various types of streetlamps, and may be introduced to streetlamps located on sidewalks, parking lots, or public transport stops, for example. Based on the image captured by the camera 20, the lighting control device 1 determines whether or not there is a moving object in the captured image and controls the lighting mode of the lighting device 3 according to the detected result.

[0011] <Lighting equipment> Lighting device 3 is a device that illuminates a predetermined area on the road surface. The area illuminated by lighting device 3 will also be referred to as the illumination area below. In this embodiment, lighting device 3 includes a light source and a drive circuit for turning on the light source. The light source is a visible light source that emits visible light. The light source is one or more LEDs (Light Emitting Diodes). Lighting device 3 may be other light sources such as fluorescent lamps or high-pressure sodium lamps. Lighting device 3 is positioned on a streetlamp in a position that forms a desired illumination area. The LED as lighting device 3 is configured to switch lighting modes in response to a control signal from the control unit 10, which will be described later. The LED as lighting device 3 changes the brightness of the light it emits in response to the control signal. Below, the brightness of the light emitted by the LED as lighting device 3 will also be referred to as the amount of light emitted.

[0012] <Camera> In this embodiment, the lighting control device 1 includes at least one camera 20. The camera 20 is a visible light camera. The camera 20 is installed on a streetlamp so as to include the road surface in its shooting range. The shooting range of the camera 20 may be set arbitrarily. The shooting range may coincide with the illumination range, be larger than the illumination range, or be smaller than the illumination range.

[0013] Camera 20 is positioned so that light from the lighting device 3 does not directly enter its lens. Specifically, in the streetlight, camera 20 is positioned closer to the road surface than the lighting device 3. In other words, camera 20 is positioned below the lighting device 3. In this embodiment, the downward direction is the direction of gravity.

[0014] The camera 20 is configured to take pictures in two shooting modes: a first exposure mode and a second exposure mode with an exposure amount larger than that of the first exposure mode. The exposure amount of the camera 20 is adjusted by changing the exposure time (shutter speed) or the aperture of the lens. The exposure amount of the first exposure mode is described as the first exposure amount hereinafter. The exposure amount of the second exposure mode is described as the second exposure amount hereinafter. The first exposure mode may be referred to as a short exposure mode in one aspect. The second exposure mode may be referred to as a long exposure mode.

[0015] In this embodiment, the first exposure amount and the second exposure amount are set in advance by the control unit 10. Note that the first exposure amount and the second exposure amount may be dynamically adjusted by a signal from the control unit 10. The first adjustment signal is a signal for adjusting the first exposure amount to a predetermined value. The second adjustment signal is a signal for adjusting the second exposure amount to a predetermined value. When the camera 20 receives the first adjustment signal, it adjusts the first exposure amount based on the first adjustment signal. When the camera 20 receives the second adjustment signal from the control unit 10, it sets the second exposure amount based on the second adjustment signal.

[0016] Note that the camera 20 may include a memory in which parameters (hereinafter referred to as camera parameters) that define the operation of the camera 20, such as the exposure time and the aperture value, are stored. The camera parameters may include parameters for the first exposure mode (e.g., exposure time) and parameters for the second exposure mode. The set values of the camera parameters may be dynamically changed by the control unit 10 as described above. Further, the camera 20 may include a ROM (Read Only Memory) in which the initial values of the camera parameters are registered. Immediately after the camera 20 is activated, it may operate according to the initial values. When the camera parameters are specified from the control unit 10, the camera 20 may save the specified set values in the memory and operate according to the set values of the parameters stored in the memory.

[0017] In this embodiment, the camera 20 alternately switches between the first exposure mode and the second exposure mode for shooting. The shooting interval of the camera 20 is set in advance by the control unit 10. The shooting interval may be, for example, 100 milliseconds. In that case, the shooting interval in each of the first exposure mode and the second exposure mode is 200 milliseconds. This is because the camera 20 alternately switches between the first exposure mode and the second exposure mode for shooting. Note that the shooting interval of the camera 20 may be arbitrarily set. The shooting interval is also one of the camera parameters.

[0018] An image captured by the camera 20 in the first exposure mode is hereinafter referred to as a first mode image. An image captured by the camera 20 in the second exposure mode is hereinafter referred to as a second mode image. Hereinafter, an image captured by the camera 20 is also referred to as a captured image. The captured image includes the first mode image and the second mode image. The camera 20 transmits first captured image data including the first mode image to the control unit 10. Hereinafter, the first captured image data may be appropriately read as the first captured image. The camera 20 transmits second captured image data including the second mode image to the control unit 10. Hereinafter, the second captured image data may be appropriately read as the second captured image.

[0019] <Control Unit> The control unit 10 is hardware that acquires a captured image from the camera 20 and controls the lighting mode of the lighting device 3 based on the captured image. The control unit 10 has a processor 11, a RAM 12, a storage 13, and an I / O 14. The processor 11 is an arithmetic core that performs arithmetic processing based on the data received from the camera 20. The processor 11 may be a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). RAM is an abbreviation for Random Access Memory.

[0020] Storage 13 is a rewritable non-volatile memory. Storage 13 may be implemented using at least one type of non-transitory tangible storage medium, such as semiconductor memory, magnetic media, and optical media. Storage 13 may include multiple types of storage media, such as ROM and flash memory. I / O 14 is an input / output circuit.

[0021] The moving objects to be detected by the control unit 10 include a first moving object and a second moving object of different types. The first moving object is a moving object equipped with a light-emitting element that emits light with a brightness of a predetermined value or higher. Hereinafter, the light-emitting element that emits light with a brightness of a predetermined value or higher will also be referred to as the predetermined light-emitting element. The predetermined light-emitting element may be a headlight used in an automobile, for example. The predetermined value may be 6000 candelas, for example. The brightness of the light-emitting element may also be expressed in lumens. The second moving object is a moving object that is not equipped with the predetermined light-emitting element.

[0022] The first moving object is, for example, a car with its headlights on. Cars include trucks, buses, motorcycles, etc. The second moving object is a pedestrian, a bicycle, or a kick scooter. In this embodiment, pedestrians, bicycles, and kick scooters may be set as the second moving object. Note that a bicycle is a bicycle as a moving object with a person on it, and may be replaced with the expression cyclist. Similarly, a kick scooter is a kick scooter as a moving object with a person on it, and may be replaced with the expression kick scooter user.

[0023] Furthermore, pedestrians carrying light-emitting devices that emit light below a specified brightness level, such as smartphones, may also be considered a second type of moving object. Similarly, bicycles with light-emitting devices that emit light below a specified brightness level illuminated may also be considered a second type of moving object.

[0024] The control unit 10 acquires a first mode image and a second mode image from the camera 20. Based on the first mode image and the second mode image, the control unit 10 determines whether or not there is a moving object within the shooting range. Based on the first mode image, the control unit 10 determines whether or not a first moving object is within the shooting range. Based on the second mode image, the control unit 10 determines whether or not a second moving object is within the shooting range.

[0025] The control unit 10 changes the detection algorithm depending on whether it is determining a first moving object based on a first mode image or a second moving object based on a second mode image. Specifically, changes to the detection algorithm include changing the features extracted from the captured image, changing the feature extraction method, changing the referenced training dataset, and changing the pattern recognition algorithm.

[0026] This section describes the process by which the control unit 10 determines the presence or absence of a first moving object based on the first mode image. In this embodiment, as an example, the control unit 10 detects light sources emitting light with a brightness of a predetermined value or higher in the first mode image. Next, it determines whether the detected light sources correspond to headlights based on the number, color, or height from the road surface of the light sources. The control unit 10 may determine an object with headlights as a first moving object, regardless of its speed of movement. In other embodiments, the control unit 10 may detect an object with headlights and a speed of movement of a predetermined value or higher as a first moving object. Detecting a first moving object corresponds to determining that a first moving object exists.

[0027] In four-wheeled vehicles, there are usually two headlights, one on each side. Therefore, the control unit 10 may determine that a four-wheeled vehicle is present in the shooting range if a pair of headlights is detected in the captured image. In motorcycles, the headlights are also arranged in a specific pattern. The control unit 10 may determine that a motorcycle is present in the shooting range if light sources arranged in a specific pattern are detected in the captured image.

[0028] Furthermore, when detecting headlights, the control unit 10 may analyze the brightness values ​​of the first mode image, set a threshold, and extract contours that define high-brightness areas. The control unit 10 may also calculate feature quantities (shape, area, position, etc.) from the extracted contours and identify whether the detected light source is a headlight or not based on the feature quantities.

[0029] Furthermore, when velocity information is used to detect the first moving object, the control unit 10 may calculate the velocity of the object with headlights based on the change in the position of the headlights detected between the first mode images that are captured in succession. The velocity of the object with headlights may be calculated by any other method.

[0030] The control unit 10 may determine the presence or absence of the first moving object by making additional determinations regarding features other than the headlights. Examples of features other than the headlights include the outline of the vehicle body and the position of the license plate.

[0031] Furthermore, the control unit 10 may determine the presence of a first moving object in the captured image if it detects a light source emitting light with a brightness of a predetermined value or higher in the first mode image. Alternatively, the control unit 10 may determine the presence or absence of a first moving object by pattern matching or other means.

[0032] Next, the process by which the control unit 10 determines the presence or absence of a second moving object based on the second mode image will be described. In this embodiment, the control unit 10 detects the second moving object by pattern matching. Alternatively, the control unit 10 may extract feature quantities of human body parts such as shoulders, head, and contours from the second mode image and detect the presence of a person, which is the second moving object, based on the spatial arrangement information of the extracted feature quantities. Various image recognition algorithms may be applied to detect the second moving object based on the second mode image.

[0033] The control unit 10 switches the lighting mode depending on whether or not it determines that a moving object is present. In this embodiment, if the control unit 10 determines that there is no moving object, it switches the lighting mode of the lighting device 3 so that the brightness is at a predetermined first level. On the other hand, if the control unit 10 determines that there is a moving object, it switches the lighting mode so that the brightness of the light emitted by the lighting device 3 is at a predetermined second level, higher than when there is no moving object. The second level corresponds to a state that is brighter than the first level. The first level may be set to a level that is sufficiently low compared to the second level (for example, half or less). The first level may also be set to the minimum level necessary to detect the second moving object in the second exposure mode. For convenience, the lighting mode applied when there is no moving object will also be referred to as the power-saving mode, and the lighting mode applied when there is a moving object will also be referred to as the normal mode.

[0034] In one embodiment, the normal mode may be a lighting mode with a greater light output (in other words, a brighter brightness) than the power-saving mode. In this disclosure, the light output in the power-saving mode is also referred to as the power-saving level, and the light output in the normal mode is also referred to as the normal level. The power-saving level and the normal level may be replaced with power-saving brightness and normal brightness, respectively. Hereinafter, the brightness of the light emitted by the lighting device 3 will also be simply referred to as the brightness of the lighting device 3.

[0035] The control unit 10 outputs a control signal to the lighting device 3 for switching the lighting mode. Specifically, the control unit 10 outputs a PWM (Pulse Width Modulation) signal as the control signal to the lighting device 3. The control unit 10 changes the control signal according to the lighting mode. The control unit 10 adjusts the brightness of the lighting device 3 by changing the duty cycle (also called the duty ratio) of the PWM signal.

[0036] The control unit 10 may also change the illumination range, flashing interval, color, or directionality of the light emitted by the lighting device 3. If the control unit 10 determines that there is a moving object, it may switch to a lighting mode in which the flashing interval of the light emitted by the lighting device 3 is shorter than when it determines that there is no moving object.

[0037] If the control unit 10 determines that a moving object is present, it may increase the light output of the lighting device 3 by a predetermined amount and direct the direction of the light emitted by the lighting device 3 towards the direction of the moving object. In this case, the direction of the light emitted by the lighting device 3 may be set to follow the movement of the moving object. If the control unit 10 determines that a moving object is present, it may also highlight the detected moving object. Thus, the lighting modes may be distinguished not only by the brightness of the lighting device 3 but also by the direction of illumination. The lighting device 3 may be configured to switch between three or more lighting modes determined by a combination of brightness and illumination direction.

[0038] If multiple moving objects are detected, the control unit 10 may select the moving object to which to direct its illumination based on a predetermined priority of moving objects. The control unit 10 may illuminate the moving object with the highest priority. The priority may be determined according to the distance to the lighting control device 1. For example, the control unit 10 may determine that the closer the distance to the lighting control device 1, the higher the priority. In addition, the priority may be predetermined for each type of moving object. For example, bicycles or pedestrians may be given a higher priority than automobiles. The term "type" may be read as "category".

[0039] When the control unit 10 switches the lighting mode, it may adjust the first exposure amount and the second exposure amount according to the brightness of the lighting mode after the switch. If the brightness of the lighting mode after the switch is brighter than before the switch, the control unit 10 may reduce the first exposure amount and the second exposure amount by a predetermined amount in conjunction with the switching of the lighting mode. In other words, when the control unit 10 switches the lighting mode from power saving mode to normal mode, it may implement control to reduce the first exposure amount and the second exposure amount by a predetermined amount.

[0040] On the other hand, if the brightness of the lighting mode after switching becomes dimmer than before switching, the control unit 10 may increase the first exposure amount and the second exposure amount by a predetermined amount in conjunction with the switching of the lighting mode. In other words, when the control unit 10 switches the lighting mode from normal mode to power saving mode, it may perform control to increase the first exposure amount and the second exposure amount by a predetermined amount.

[0041] Adjusting the exposure amount is equivalent to changing the camera parameters applied to the camera 20. The storage 13 of the control unit 10 may store a first parameter setting that defines a first exposure amount for power saving mode and a second parameter setting that defines a first exposure amount for normal mode. The storage 13 may also store a third parameter setting that defines a second exposure amount for power saving mode and a fourth parameter setting that defines a second exposure amount for normal mode.

[0042] The parameters that define the exposure amount may be exposure time, aperture value, or a combination of exposure time and aperture value. For example, the second parameter setting may have an exposure time set to be a predetermined amount shorter than the first parameter setting. The fourth parameter setting may have an exposure time set to be a predetermined amount shorter than the third parameter setting. The control unit 10 outputs a first adjustment signal and a second adjustment signal to the camera 20 in order to adjust the first exposure amount and the second exposure amount in conjunction with (for example, prior to) the switching of the lighting mode. The adjustment signal may be a signal that includes the setting value of the camera parameter to be newly applied (for example, exposure time).

[0043] The control unit 10 adjusts the first exposure amount so that the average brightness of the first mode image before switching the lighting mode and the average brightness of the first mode image after switching the lighting mode fall within a predetermined range. The control unit 10 adjusts the second exposure amount so that the average brightness of the second mode image before switching the lighting mode and the average brightness of the second mode image after switching the lighting mode fall within a predetermined range.

[0044] When the lighting mode is switched, the brightness of the shooting range may change depending on the brightness of the lighting mode. This may also change the appropriate exposure amount. Therefore, it is expected that the control unit 10 will adjust the first exposure amount and the second exposure amount according to the brightness of the lighting mode, so that the appropriate exposure amount can be obtained even when the lighting mode is switched.

[0045] <Lighting control flow> Next, the lighting control process performed by the control unit 10 will be explained using the flowcharts shown in Figures 2, 3, and 4. The lighting control process starts when the area around the lighting control device 1 becomes dark and ends when the area around the lighting control device 1 becomes bright. For example, the lighting control device 1 may be equipped with an illuminance sensor that detects external illuminance, and the lighting control process may be executed based on the detection value of the illuminance sensor falling below a predetermined value. The illuminance sensor may be placed in a location that does not receive light from the lighting device 3, for example, above the lighting device 3. The lighting control process may start at night and end in the morning. The lighting control process is repeated.

[0046] Figure 2 shows the flow of processing performed by camera 20. Figure 3 shows the flow of lighting control processing performed by control unit 10 during power saving mode. The flow in Figure 3 is executed periodically while the lighting device 3 is set to power saving mode. Figure 4 shows the flow of lighting control processing performed by control unit 10 when the lighting device 3 is lit in normal mode. In the flow description, "S" means step. For example, the notation S11 may be replaced with step 11 or step S11.

[0047] First, an example of the operation of camera 20 will be explained using Figure 2. Camera 20 repeatedly performs the flow shown in Figure 2 while the execution conditions for the lighting control process are met, for example, while the output of the illuminance sensor is below a predetermined value. In S11, camera 20 takes a picture in the first exposure mode. In S12, camera 20 transmits the first mode image data to the control unit 10. In S13, camera 20 takes a picture in the second exposure mode. In S14, it transmits the second mode image data to the control unit 10. Then, returning to S11, camera 20 performs the flow shown in Figure 2 again. The shooting interval may be designed as appropriate.

[0048] Next, the processing performed by the control unit 10 will be explained (Figure 3). During power saving mode, the control unit 10 repeatedly performs the flow shown in Figure 3. In S21, the control unit 10 acquires a first mode image from the camera 20. The first mode image acquired here is the first mode image transmitted in S12. In S22, the control unit 10 determines whether the first moving object is within the shooting range based on the first mode image. In S22, if the result is YES, proceed to S23; otherwise, proceed to S24.

[0049] In S23, the control unit 10 switches the lighting mode to increase the brightness of the lighting device 3. Specifically, the control unit 10 switches the lighting mode from power-saving mode to normal mode. The control unit 10 sends a control signal to the lighting device 3 to switch from power-saving mode to normal mode. Upon receiving the control signal, the lighting device 3 switches the lighting mode according to the control signal.

[0050] After transmitting the control signal, the control unit 10 adjusts the exposure amount of the first exposure mode and the second exposure mode according to the brightness of the switched lighting mode. The control unit 10 transmits a first adjustment signal and a second adjustment signal to the camera 20 in order to adjust the first exposure amount and the second exposure amount. The first adjustment signal and the second adjustment signal may be included in the control signal or transmitted to the camera 20 together with the control signal. After the processing in S23 is completed, the control unit 10 starts the lighting control processing in normal mode (Figure 4), which will be described later.

[0051] In S24, the control unit 10 acquires a second-mode image from the camera 20. The first-mode image acquired here is the second-mode image transmitted in S14. In S25, the control unit 10 determines, based on the second-mode image, whether the second moving object is within the shooting range. If the answer in S24 is YES, the process proceeds to S23; if it is NO, it returns to S21, and the control unit 10 repeats the flow shown in Figure 3.

[0052] In S26, the control unit 10 switches the lighting mode to increase the brightness of the lighting device 3. Specifically, similar to S23, the control unit 10 switches the lighting mode from power-saving mode to normal mode. Similar to S23, the control unit 10 sends a control signal to the lighting device 3 to increase its brightness. Upon receiving the control signal, the lighting device 3 switches the lighting mode according to the control signal. Similar to S23, after sending the control signal, the control unit 10 adjusts the exposure amount of the first exposure mode and the second exposure mode according to the brightness of the switched lighting mode. Similar to S23, the control unit 10 sends a first adjustment signal and a second adjustment signal to the camera 20 to adjust the first exposure amount and the second exposure amount. After the processing in S23 is completed, the control unit 10 starts the lighting control processing in normal mode (Figure 4).

[0053] As described above, if a moving object is detected in either the first mode image or the second mode image, the control unit 10 switches the lighting mode from power-saving mode to normal mode. Note that the analysis processing of the first mode image in S21 to S22 may be performed while the camera 20 is shooting in the second exposure mode. Similarly, the analysis processing of the second mode image in S24 to S25 may be performed while the camera 20 is shooting in the first exposure mode.

[0054] Next, the lighting control process performed by the control unit 10 when the lighting device 3 is lit in normal mode will be explained using the flowchart shown in Figure 4. Even in normal mode, the camera 20 repeatedly performs the flow shown in Figure 2. In Figure 4, at the start of the flow, the lighting device 3 is set to normal mode.

[0055] During normal mode, the control unit 10 repeatedly performs the flow shown in Figure 4. In S31, the control unit 10 acquires a first mode image from the camera 20. The first mode image acquired here is the first mode image transmitted in S12. In S32, the control unit 10 determines whether the first moving object is within the shooting range based on the first mode image. In S22, if the result is YES, the process of switching the lighting mode is not performed, and the control unit 10 returns to S31 and performs the flow shown in Figure 4 again. In S32, if the result is NO, the process proceeds to S33.

[0056] In S33, the control unit 10 acquires a second mode image from the camera 20. The second mode image acquired here is the same second mode image transmitted in S14. In S34, the control unit 10 determines, based on the second mode image, whether or not the second moving object is within the shooting range. In S24, if the result is YES, the process of switching the lighting mode is not performed, and the process returns to S31, where the control unit 10 repeats the flow shown in Figure 4. In S24, if the result is NO, the process proceeds to S35.

[0057] In S35, the control unit 10 switches the lighting mode to reduce the brightness of the lighting device 3. Specifically, the control unit 10 switches the lighting mode from normal mode to power-saving mode. The control unit 10 transmits a control signal to the lighting device 3 to switch from normal mode to power-saving mode. Upon receiving the control signal, the lighting device 3 switches the lighting mode according to the control signal.

[0058] After transmitting the control signal, the control unit 10 adjusts the exposure amount of the first exposure mode and the second exposure mode according to the brightness of the switched lighting mode. The control unit 10 transmits the first adjustment signal and the second adjustment signal to the camera 20 in order to adjust the first exposure amount and the second exposure amount. After the processing in S35 is completed, the control unit 10 starts the lighting control processing in power saving mode (Figure 3).

[0059] As described above, if no moving object is detected in either the first mode image or the second mode image, the control unit 10 switches the lighting mode back from normal mode to power-saving mode. This reduces power consumption. If a moving object is detected in either the first mode image or the second mode image, the control unit 10 maintains normal mode. This reduces the risk of dimming the lighting when a moving object is present. Note that the analysis processing of the first mode image in S31-S32 may be performed while the camera 20 is shooting in second exposure mode. Similarly, the analysis processing of the second mode image in S33-S34 may be performed while the camera 20 is shooting in first exposure mode.

[0060] <Summary of the First Embodiment> According to this configuration, when the lighting device 3 is lit in power-saving mode, the control unit 10 determines whether or not a moving object is present from images taken in two different shooting modes with different exposure levels. As a result, even if the control unit 10 cannot detect a moving object from an image taken in one exposure mode, it is expected that it can detect a moving object from an image taken in the other shooting mode. In other words, the risk of the control unit 10 failing to detect a moving object is reduced. Consequently, the risk of the power-saving mode being maintained even when a moving object is present near the streetlamp is reduced. In short, the control unit 10 can appropriately control the lighting mode of the lighting device 3.

[0061] Furthermore, in this embodiment, when the lighting device 3 is lit in normal mode, the control unit switches the lighting mode to power-saving mode when it detects that no moving object is detected in either the first mode image or the second mode image. This reduces power consumption during standby.

[0062] In this configuration, different types of moving objects are set as detection targets for the first mode image and the second mode image. Specifically, the control unit 10 attempts to detect a first moving object, which is a moving object equipped with a light emitter that emits light of a brightness above a predetermined value, from the first mode image, which has a relatively small exposure amount. The control unit 10 also attempts to detect a second moving object, which is a moving object that does not have a light emitter, from the second mode image, which has a long exposure amount.

[0063] In dark environments, photographing pedestrians and other objects in the first exposure mode results in insufficient light, making it difficult to detect them in the captured image. On the other hand, photographing vehicles in the second exposure mode can result in flare, overexposure, or motion blur in the captured image, making it difficult to detect the vehicle.

[0064] To address such challenges, this configuration allows the control unit 10 to detect both moving objects equipped with light-emitting elements that emit a brightness above a predetermined value, and moving objects that do not have light-emitting elements, even in dark environments. In other words, it becomes possible to detect two types of moving objects.

[0065] Furthermore, the control unit 10 of this embodiment applies different object recognition algorithms to the two mode images, taking into account the characteristics of the captured image and the characteristics of the moving object to be detected. In other words, the algorithm for detecting a moving object from the first mode image is different from the algorithm for detecting a moving object from the second mode image. With this configuration, the first and second moving objects can be detected with high accuracy.

[0066] In this configuration, the first moving object is a car with its headlights on, and the second moving object is a pedestrian, bicycle, or kick scooter. The combination of second moving objects to be detected can be designed as appropriate. The second moving object may be just one of the pedestrian, bicycle, and kick scooter, or any two of them.

[0067] In this configuration, the camera 20 is controlled to alternately switch between two shooting modes. This allows the control unit 10 to acquire two types of images, a first-mode image and a second-mode image, using a single camera 20. Therefore, with this configuration, the control unit 10 can detect two types of moving objects with different self-illuminating amounts using a single camera 20.

[0068] <Example 1> When the lighting device 3 is lit in normal mode, the control unit 10 may determine whether there is an approaching object, which is a moving object, whose time until it enters a predetermined area on the road surface is less than or equal to a predetermined time. If the control unit 10 determines that there is an approaching object, it may be configured to switch the lighting mode to illuminate the road area related to the approaching object's path. The predetermined area may be the area around the streetlamp where the lighting control device 1 is installed. Alternatively, the predetermined area may be an intersection or pedestrian crossing near the streetlamp where the lighting control device 1 is installed. The road area related to the approaching object's path may be the expected path of the approaching object, a pedestrian crossing near the approaching object's path, etc. Alternatively, if the approaching object is a vehicle with headlights, the road area related to the approaching object's path may be the area not illuminated by the approaching object's headlights. In this disclosure, a moving object determined to be within the shooting range based on the first mode image and the second mode image is also referred to as a detected moving object.

[0069] The control unit 10 may calculate the speed of the detected moving object in order to detect the approaching object. Based on the position and speed of the detected moving object, the control unit 10 determines whether the time it takes for the detected moving object to enter a predetermined area is less than or equal to a predetermined time. The control unit 10 may calculate the position of the detected moving object using image processing techniques. The control unit 10 may calculate the speed of the detected moving object based on the change in the position of the detected moving object between consecutive captured images. The position and speed of the detected moving object may be calculated by any other method.

[0070] When the control unit 10 determines that the time it takes for the detected moving object to enter a predetermined area is less than or equal to a predetermined time, it determines that there is an approaching object. If the control unit 10 determines that there is an approaching object, it sends a control signal to the lighting device 3 to change the directionality so that it illuminates the road area related to the approaching object's path.

[0071] According to this disclosure, the area related to the path of a moving object entering a predetermined area, such as an intersection, within a predetermined time is illuminated. This makes it easier for vehicles or pedestrians in the vicinity of the predetermined area to recognize the presence of the approaching object before it enters the area. This is expected to help prevent traffic accidents.

[0072] <Other variations> The first and second moving objects may be different in terms of their movement speed, or in other words, in terms of the probability of motion blur occurring. For example, the first moving object may be a bicycle or a kick scooter, and the second moving object may be a pedestrian.

[0073] The above describes an embodiment using two types of captured images with different exposure levels, but the control unit 10 may be configured to detect three or more types of moving objects using three or more captured images, each with different exposure levels. For example, it may be configured to detect a car with its headlights on from the image with the shortest exposure level, a pedestrian from the image with the longest exposure level, and a bicycle or kick scooter from the image with an intermediate exposure level. Accordingly, the camera 20 may have three or more shooting modes, each with different exposure levels.

[0074] The lighting control device 1 may be installed in places other than streetlights. The lighting control device 1 may be installed on structures such as traffic lights or utility poles.

[0075] The light source of the lighting device 3 may consist of multiple LEDs arranged in an array. The control unit 10 may dynamically change the directionality of the light source as a whole by individually controlling each LED.

[0076] The control unit 10 may change the directionality of the light emitted by the lighting device 3 without changing the amount of light emitted between power-saving mode and normal mode. For example, in power-saving mode, the directionality may be directed directly below the streetlamp, and in normal mode, the directionality may be directed towards the detected moving object.

[0077] When switching lighting modes, the control unit 10 may adjust only one of the exposure amounts, either the first exposure amount or the second exposure amount, according to the brightness of the lighting mode after the switch. For example, when switching lighting modes, the control unit 10 may adjust only the first exposure amount according to the brightness of the lighting mode after the switch.

[0078] Furthermore, when the lighting device 3 is lit in normal mode, the camera 20 may be configured to only shoot in the first exposure mode and not in the second exposure mode. In other words, when the lighting device 3 is lit in power-saving mode, the camera 20 may be configured to shoot alternately in the two exposure modes, while when the lighting device 3 is lit in normal mode, it may be configured to only shoot in the first exposure mode. This is because in normal mode, the shooting range is expected to be bright.

[0079] <Second Embodiment> This embodiment is a modification based on a prior embodiment, and the description of the prior embodiment can be referenced. In the first embodiment, one camera 20 performed shooting by alternately switching between two shooting modes. In the second embodiment, the camera 20 is composed of a first camera that shoots in a first exposure mode and a second camera that shoots in a second exposure mode. The shooting range of the first camera and the shooting range of the second camera may be the same or different. The control unit 10 acquires a first mode image from the first camera and a second mode image from the second camera.

[0080] In the second embodiment, the camera 20 used for shooting differs depending on the shooting mode. Here, for example, if two shooting modes are alternately shot using one camera 20, it is not possible to shoot in the other mode while the camera 20 is shooting in one shooting mode. According to this embodiment, it becomes possible to shoot in the other mode even while shooting in one shooting mode. Therefore, with this configuration, the control unit 10 can shorten the detection interval for the first moving object and the detection interval for the second moving object.

[0081] <Third Embodiment> This embodiment is a modification based on a prior embodiment, and the description of the prior embodiment can be referenced. In the first embodiment, the lighting device 3 had a visible light source that emitted visible light. In contrast, in the third embodiment, as shown in Figure 5, the lighting device 3 further includes an infrared light source 32 in addition to the visible light source 31. The infrared light source 32 is hardware that emits infrared rays toward the road surface, and may be implemented using, for example, an infrared LED. The irradiation range of the infrared light source 32 includes the irradiation range of the visible light source 31 and is set to be wider than the irradiation range of the visible light source 31. The infrared light source 32 is configured to switch its lighting state in response to a signal from the control unit 10. Specifically, the infrared light source 32 switches between being on and off in response to a signal from the control unit 10.

[0082] In this embodiment, the camera 20 includes an infrared camera 22 in addition to a visible light camera 21. The visible light camera 21 is configured to capture images in two shooting modes, a first exposure mode and a second exposure mode, similar to the first embodiment. The images captured by the visible light camera 21 are also referred to as visible light images. Visible light images include first mode images and second mode images. The shooting range of the visible light camera 21 may coincide with the illumination range of the visible light source 31, or it may be larger or smaller than the illumination range of the visible light source 31.

[0083] The shooting range of the infrared camera 22 may coincide with the illumination range of the infrared light source 32, or it may be larger or smaller than the illumination range of the infrared light source 32. The shooting range of the visible light camera 21 will also be referred to as the visible light shooting range below. The shooting range of the infrared camera 22 will also be referred to as the infrared shooting range below. The infrared shooting range corresponds to a predetermined range.

[0084] The control unit 10 operates the infrared light source 32 and the infrared camera 22 when specific monitoring conditions are met. These specific monitoring conditions include situations such as being within a specific time period or when the external illumination is below a predetermined value. Images captured by the infrared camera 22 are also referred to as infrared images.

[0085] The control unit 10 determines whether or not there is a moving object within the infrared imaging range based on the infrared image. The moving object that the control unit 10 detects based on the infrared image includes a first moving object and a second moving object. The control unit 10 determines whether or not there is a moving object within the infrared imaging range using image recognition technology.

[0086] The control by the control unit 10 in this embodiment will now be described. When specific monitoring conditions are met, the control unit 10 controls the lighting device 3 to turn on the infrared light source 32 and turn on the visible light source 31 in power-saving mode. The control unit 10 then operates the infrared camera 22. The control unit 10 in this embodiment also operates the visible light camera 21. While the visible light source 31 is set to power-saving mode, the control unit 10 detects the presence or absence of a moving object based on the infrared image and also attempts to detect the presence or absence of a moving object based on the visible light image.

[0087] When the control unit 10 detects a moving object from an infrared or visible light image, it switches the illumination mode of the visible light source 31 from power-saving mode to normal mode. When the control unit 10 switches the illumination mode of the visible light source 31 to normal mode, it may output an exposure adjustment signal to the visible light camera 21. In addition, when the control unit 10 switches the illumination mode of the visible light source 31 to normal mode, it may turn off the infrared light source 32 and stop the infrared camera 22.

[0088] In other embodiments, the visible light camera 21 may be kept stopped while the visible light source 31 is set to power-saving mode. In this case, while the visible light source 31 is set to power-saving mode, the control unit 10 will attempt to detect the moving object using only the infrared image. Alternatively, the control unit 10 may start taking images with the visible light camera 21 after it has switched the lighting mode of the visible light source 31 from power-saving mode to normal mode.

[0089] While the visible light source 31 is set to normal mode, the control unit 10 detects a first moving object or a second moving object based on the first mode image and the second mode image acquired from the visible light camera 21. While the visible light source 31 is set to normal mode, the control unit 10 may continue or stop detecting moving objects based on infrared images.

[0090] <Lighting control flow> Next, the lighting control process performed by the control unit 10 will be explained using the flowcharts shown in Figures 6 and 7. The lighting control process is performed while specific monitoring conditions are met. Here, as an example, the specific monitoring condition is when the surrounding area of ​​the lighting control device 1 is below a predetermined value.

[0091] Figure 6 shows the flow of the lighting control process performed by the control unit 10 when the visible light source 31 is set to power saving mode. The flow in Figure 6 is executed periodically while the visible light source 31 is set to power saving mode. Figure 7 shows the flow of the lighting control process performed by the control unit 10 when the visible light source 31 is set to normal mode. The flow in Figure 7 is executed periodically while the visible light source 31 is set to normal mode.

[0092] As soon as the lighting control process begins, the control unit 10 sends a control signal to the lighting device 3 to turn on the infrared light source 32 and set the visible light source 31 to power-saving mode. The control unit 10 also sends a signal to the camera 20 to operate the infrared camera 22 and the visible light camera 21.

[0093] The process performed by the control unit 10 when the visible light source 31 is lit in power-saving mode will be described (Figure 6). In S41, the control unit 10 acquires an infrared image from the infrared camera 22. In S42, the control unit 10 determines whether the moving object is within the infrared imaging range based on the infrared image. If the result in S42 is YES, proceed to S47. If the result in S42 is NO, proceed to S43.

[0094] In S43, the control unit 10 acquires a first mode image from the visible light camera 21. In S44, the control unit 10 determines, based on the first mode image, whether the first moving object is within the shooting range. In S44, if the answer is YES, the process proceeds to S47; otherwise, the process proceeds to S45.

[0095] In S45, the control unit 10 acquires a second-mode image from the visible light camera 21. In S46, the control unit 10 determines, based on the second-mode image, whether the second moving object is within the shooting range. If the result in S46 is YES, the process proceeds to S47; otherwise, the control unit 10 repeats the flow shown in Figure 6 from S41.

[0096] In S47, the control unit 10 switches the lighting mode to increase the brightness of the visible light source 31. Specifically, the control unit 10 switches the lighting mode of the visible light source 31 from power-saving mode to normal mode.

[0097] Here, as an example, when the visible light source 31 is in normal mode, the control unit 10 stops detecting moving objects based on infrared images. The control unit 10 controls the infrared light source 32 to turn off and the infrared camera 22 to stop. Specifically, the control unit 10 turns off the infrared light source 32 and sends a control signal to the lighting device 3 to switch the lighting mode of the visible light source 31 from power-saving mode to normal mode. Upon receiving the control signal, the lighting device 3 switches the lighting state of the infrared light source 32 and the lighting mode of the visible light source 31 according to the control signal. This reduces power consumption during normal mode.

[0098] Following the above process, the control unit 10 may send a signal to the camera 20 to stop shooting with the infrared camera 22 and continue shooting with the visible light camera 21. Upon receiving the signal, the camera 20 stops shooting with the infrared camera 22 while continuing to shoot with the visible light camera 21. After the process in S47 is completed, the control unit 10 starts the lighting control process (Figure 7) for the visible light source 31 while it is in normal mode.

[0099] Next, we will explain the process performed by the control unit 10 when the visible light source 31 is lit in normal mode (Figure 7). In S51, the control unit 10 acquires a first mode image from the visible light camera 21. In S52, the control unit 10 determines whether the first moving object is within the shooting range based on the first mode image. In S52, if the result is YES, the process of switching the lighting mode of the visible light source 31 is not performed, and the process returns to S51, where the control unit 10 repeats the flow shown in Figure 7. In S52, if the result is NO, the process proceeds to S53.

[0100] In S53, the control unit 10 acquires a second-mode image from the visible light camera 21. In S54, the control unit 10 determines, based on the second-mode image, whether the second moving object is within the shooting range. In S54, if the result is YES, the process of switching the lighting mode of the visible light source 31 is not performed, and the process returns to S51, where the control unit 10 repeats the flow shown in Figure 7. In S54, if the result is NO, the process proceeds to S55.

[0101] In S55, the control unit 10 switches the lighting mode to reduce the brightness of the visible light source 31. Specifically, the control unit 10 switches the lighting mode of the visible light source 31 from normal mode to power saving mode.

[0102] In other words, in S55, the control unit 10 transmits a control signal to the lighting device 3 to turn on the infrared light source 32 and switch the lighting mode of the visible light source 31 from normal mode to power-saving mode. Upon receiving the control signal, the lighting device 3 switches the lighting state of the infrared light source 32 and the lighting mode of the visible light source 31 according to the control signal.

[0103] Furthermore, in S55, the control unit 10 sends a signal to camera 20 to start shooting with the infrared camera 22 and continue shooting with the visible light camera 21. Upon receiving the signal, camera 20 starts shooting with the infrared camera 22 and continues shooting with the visible light camera 21. After the processing in S55 is completed, the control unit 10 starts the lighting control process (Figure 6) for the visible light source 31 while it is in power saving mode.

[0104] Note that the configuration and execution order of the steps in each flowchart are examples and may be changed as appropriate. In the lighting control flow described above, when the visible light source 31 is in normal mode, the control unit 10 stops detecting moving objects based on infrared images, but this does not have to be done. Even when the visible light source 31 is in normal mode, detection of moving objects based on infrared images may continue. In other words, the flowchart shown in Figure 7 may include steps S41 to S42. In that case, the control unit 10 may be configured to maintain normal mode when a moving object is detected based on infrared images.

[0105] Furthermore, in the lighting control flow described above, when the visible light source 31 was in power-saving mode, the control unit 10 performed both detection of moving objects based on infrared images and detection of moving objects based on visible light images. As another example, when the visible light source 31 was in power-saving mode, detection of moving objects based on visible light images may not be performed, and only detection of moving objects based on infrared images may be performed. In other words, the processes S43 to S46 may be omitted.

[0106] <Summary of the third embodiment> When the control unit 10 detects a moving object using a visible light image, it may not be able to detect the moving object in a dark environment. Also, even in the second exposure mode, it may fail to detect the second moving object under certain conditions. In the configuration of this embodiment, the presence or absence of a moving object is determined not only based on the visible light image but also on the infrared image. According to the configuration of this embodiment, it may be possible to detect a moving object that cannot be detected by the visible light image using the infrared image. This improves the possibility of detecting a moving object. Therefore, it can be expected that the lighting mode of the lighting device 3 will be switched appropriately.

[0107] <Variation> The illumination range of the visible light source may be set to coincide with the illumination range of the infrared light source, or it may be set to be greater than or equal to the illumination range of the infrared light source.

[0108] The lighting device 30 in the third embodiment may also have an ultra-power-saving mode with an even lower light output than the power-saving mode. When no moving object is detected, the control unit 10 may switch to the ultra-power-saving mode. In the ultra-power-saving mode, the brightness of the visible light source 31 may be set to a level at which the second moving object cannot be detected even in the second exposure mode. Based on the detection of a moving object by infrared image, the control unit 10 may switch to the power-saving mode, or switch from the ultra-power-saving mode to the normal mode. In the power-saving mode, the brightness of the visible light source 31 may be set to a level at or above the minimum level necessary to detect the second moving object in the second exposure mode.

[0109] In any embodiment, the control unit 10 may be configured to gradually change the amount of light emitted by the lighting device 30 over a certain period of time, rather than switching it in steps. For example, dimming from the normal level to the energy-saving level may be done in stages (or continuously). For example, dimming from the normal level to the energy-saving level may be done slowly over about 5 seconds. Dimming from the energy-saving level to the normal level may also be done in stages over a certain period of time. [Explanation of Symbols]

[0110] 1...Lighting control device, 3...Lighting device, 10...Control unit, 11...Processor, 12...RAM, 13...Storage, 14...I / O, 20...Camera, 21...Visible light camera, 22...Infrared camera, 31...Visible light source, 32...Infrared light source, 100...Lighting control system.

Claims

1. A lighting control device that controls the lighting mode of a lighting device configured to irradiate light toward the road surface, A camera (20) is installed so as to include the aforementioned road surface in its shooting range, The system includes a control unit (10) that acquires an image from the camera and controls the lighting mode of the lighting device based on the image, The camera is configured to shoot in two shooting modes: a first exposure mode and a second exposure mode in which the exposure amount is greater than that of the first exposure mode. The control unit, The camera acquires a first mode image, which is an image taken in the first exposure mode, and a second mode image, which is an image taken in the second exposure mode. Based on the first mode image and the second mode image, it is determined whether or not there is a moving object within the shooting range. A lighting control device configured to switch the lighting mode depending on whether or not it is determined that the moving object is present.

2. The moving body to be detected by the control unit includes a first moving body and a second moving body of different types. The control unit, Based on the first mode image, it is determined whether the first moving object is within the shooting range. The lighting control device according to claim 1, which determines whether the second moving object is within the shooting range based on the second mode image.

3. The first mobile body is a mobile body that includes a light-emitting element that emits light with a brightness of a predetermined value or higher, The lighting control device according to claim 2, wherein the second mobile body is the mobile body that does not include the light-emitting body.

4. The first moving object is a car with its headlights on, The lighting control device according to claim 2, wherein the second moving body is a pedestrian, a bicycle, or a kick scooter.

5. The control unit, The lighting control device according to any one of claims 1 to 4, wherein when switching the lighting mode, the exposure amounts of the first exposure mode and the second exposure mode are adjusted according to the brightness of the lighting mode after switching.

6. The lighting control device according to any one of claims 1 to 4, wherein the control unit controls the camera to alternately switch between the two shooting modes while taking pictures.

7. The camera includes a first camera and a second camera, The first camera takes a picture in the first exposure mode, The second camera is configured to shoot in the second exposure mode, The control unit, The first mode image is acquired from the first camera. The lighting control device according to any one of claims 1 to 4, configured to acquire the second mode image from the second camera.

8. The control unit, It is determined whether or not there is an approaching object, which is a moving object, whose time until it enters a predetermined area on the road surface is less than or equal to a predetermined time. The lighting control device according to any one of claims 1 to 4, which, when it is determined that there is an approaching object, switches the lighting mode to illuminate the road area related to the path of the approaching object.

9. The aforementioned lighting device is a visible light source (31) that emits visible light, The system further comprises an infrared light source (32) that irradiates infrared rays toward the road surface, The camera includes a visible light camera (21) and an infrared camera (22). The control unit, When specific monitoring conditions are met, the infrared light source and the infrared camera are activated. Based on the image captured by the infrared camera, it is determined whether or not the moving object is within a predetermined range. If it is determined that the moving object is not within the predetermined range, the lighting mode of the visible light source is set to a power-saving mode in which the amount of light emitted is less than or equal to a predetermined value. The lighting control device according to any one of claims 1 to 4, wherein when it is determined that the moving body is within the predetermined range, the lighting mode of the visible light source is switched from the power saving mode to a normal mode in which the amount of light emitted is greater than that of the power saving mode.

Images