Estimation device, illumination control device, illumination control system, estimation method, illumination control method, estimation program, and illumination control program

Abstract

This estimation device is provided with: an acquisition unit for acquiring measurement results of the brightness at two or more points located in an illumination control area which is defined by a ceiling, a floor, and a wall and which has an extraneous light incidence unit located on the wall; and an estimation unit for estimating, on the basis of the measurement results of the brightness at the two or more points, the main direction of the extraneous light incident through the external light incidence unit from outside of the illumination control area.

Description

Estimation device, lighting control device, lighting control system, estimation method, lighting control method, estimation program, and lighting control program Cross-reference to related applications

[0001] This application claims priority from Japanese Patent Application No. 2024-3505 (filed January 12, 2024), the entire disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to an estimation device, a lighting control device, a lighting control system, an estimation method, a lighting control method, an estimation program, and a lighting control program.

[0003] Patent Document 1 describes a system for calculating the daylight illuminance in a room based on the daylight factor corresponding to the position of the sun.

[0004] JP 2013-218962 A

[0005] An estimation device according to an embodiment of the present disclosure includes an acquisition unit and an estimation unit. The acquisition unit acquires brightness measurement results of at least two points located in a lighting-controlled area partitioned by a ceiling, a floor, and walls and having an external light incident unit located on the walls. The estimation unit estimates a main direction of external light entering the lighting-controlled area from outside through the external light incident unit based on the brightness measurement results of the at least two points.

[0006] A lighting control device according to an embodiment of the present disclosure controls lighting devices installed in the lighting control area based on the brightness estimation result obtained by the estimation device.

[0007] A lighting control system according to an embodiment of the present disclosure includes the estimation device, the lighting control device, and lighting devices installed in the lighting control area.

[0008] An estimation method according to an embodiment of the present disclosure includes an estimation device acquiring brightness measurement results of at least two points located in a lighting-controlled area partitioned by a ceiling, a floor, and walls and having an external light entrance portion located on the walls, and estimating, by the estimation device, a main direction of external light entering the lighting-controlled area from outside through the external light entrance portion based on the brightness measurement results of the at least two points.

[0009] A lighting control method according to one embodiment of the present disclosure includes a lighting control device controlling lighting devices installed in the lighting control area based on brightness estimation results obtained by executing the estimation method.

[0010] An estimation program according to an embodiment of the present disclosure causes an estimation device to acquire brightness measurement results of at least two points located in a lighting-controlled area partitioned by a ceiling, a floor, and walls and having an external light incident portion located on the wall. The estimation program causes the estimation device to estimate a main direction of external light entering the lighting-controlled area from outside the lighting-controlled area through the external light incident portion based on the brightness measurement results of the at least two points.

[0011] A lighting control program according to an embodiment of the present disclosure causes a lighting control device to control lighting devices installed in the lighting control area based on the brightness estimation result obtained by executing the estimation program.

[0012] FIG. 1 is a block diagram showing an example of the configuration of a lighting control system according to an embodiment; FIG. 2 is a schematic diagram showing an example of the configuration of a lighting control area; FIG. 3 is a side view showing an example of the configuration of a lighting control area; FIG. 4 is a plan view showing an example of the configuration of a lighting control area; FIG. 5 is a schematic diagram illustrating an example of the traveling direction of extraneous light incident from an extraneous light incident unit; FIG. 6 is a plan view showing an example of the arrangement of measurement points; FIG. 7 is a plan view illustrating the components of light incident on each measurement point when the traveling direction of extraneous light is inclined to the horizontal direction; FIG. 8 is a plan view illustrating the components of light incident on each measurement point when the traveling direction of extraneous light is inclined to the vertical direction; FIG. 9 is a flow chart showing an example of the flow of information calculated or estimated by an estimation device; FIG. 10 is a flowchart showing an example of the procedure of an estimation method according to an embodiment; FIG. 11 is a flowchart showing an example of the procedure of a lighting control method according to an embodiment;

[0013] (Configuration example of lighting control system 1) As shown in Figure 1, a lighting control system 1 according to one embodiment includes a lighting control device 10, a brightness measurement device 20, and a lighting device 40. As illustrated in Figures 2A, 2B, and 2C, the lighting device 40 and the brightness measurement device 20 are located in a lighting control area 100. The number of lighting devices 40 is not limited to one and may be two or more. The positions of the lighting devices 40 may be determined as appropriate. The number of brightness measurement devices 20 is two or more. The positional relationships between the multiple brightness measurement devices 20 will be described below.

[0014] The lighting-controlled area 100 may include various spaces for which lighting is to be controlled, such as an office, a conference room, or a classroom. The lighting-controlled area 100 is a space partitioned by a ceiling 110, a floor 120, and a wall 130. The wall 130 has an external light entrance section 140 that transmits external light 50 (see FIGS. 2B and 2C ). The external light 50 brightens the lighting-controlled area 100. The external light entrance section 140 may be a window or an opening.

[0015] In this embodiment, the lighting device 40 and the brightness measurement device 20 are located on the ceiling 110 of the lighting controlled area 100. The lighting device 40 emits illumination light 60 (see FIG. 2B ) from the ceiling 110. The illumination light 60 brightens the lighting controlled area 100.

[0016] The brightness of each point in the lighting-controlled area 100 corresponds to the intensity of light incident on each point. The light incident on each point includes direct light and indirect light. Direct light is light that is external light 50 or illumination light 60 that directly enters each point. Indirect light is light that is the illumination light 60 or external light 50 that enters after being reflected or scattered at another point. In this embodiment, the intensity of indirect light is considered to be negligibly small compared to the intensity of direct light. Hereinafter, it is assumed that the brightness of each point in the lighting-controlled area 100 is determined by the intensity of direct light that enters each point.

[0017] The brightness measuring device 20 measures the brightness of a measurement point 80 located on the floor 120. The brightness of the measurement point 80 is determined according to the intensity of the illumination light 60 and the intensity of the external light 50 incident on the measurement point 80. The stronger the light incident on the measurement point 80, the brighter the measurement point 80. The brightness of the measurement point 80 may be expressed as the illuminance of light at the measurement point 80. The brightness of the measurement point 80 may also be expressed by a value estimated based on an image of the measurement point 80. In other words, the brightness value of the measurement point 80 may be a value estimated based on an image of the measurement point 80. For example, the brightness measuring device 20 may image the measurement point 80 in YUV format and measure a value calculated from the luminance signal Y of the image as a value representing the brightness of the measurement point 80. The brightness of the measurement point 80 is not limited to these examples and may be expressed as various other physical quantities. The brightness of the measurement point 80 may be expressed by various indices.

[0018] The external light 50 is light that enters the lighting-controlled area 100 through the external light entrance section 140. The external light 50 includes light scattered by the atmosphere, i.e., light incident from a blue sky 141 (see FIG. 2A ), or light scattered by clouds. Clouds may be classified as white clouds 142 or black clouds 143 (see FIG. 2A ), depending on the intensity of light reaching the lighting-controlled area 100. The white clouds 142 are clouds that appear bright due to the strong light that reaches the lighting-controlled area 100. The black clouds 143 are clouds that appear dark due to the weak light that reaches the lighting-controlled area 100.

[0019] When the intensity of light incident on the external light incident section 140 is uniform in all directions, the intensities of the components of external light 50 in each direction are approximately equal. For example, if all you can see when looking outside from the external light incident section 140 is blue sky 141, the intensity of light incident on the external light incident section 140 may be uniform in all directions. This is because the blue sky 141 is observed as a result of uniform blue light being incident on the external light incident section 140.

[0020] 2A , when looking outside from external light incident portion 140, not only blue sky 141 but also white clouds 142 or black clouds 143 may be seen. In this case, a distribution occurs in the intensity of the components of external light 50 in each direction. Specifically, the light component incident from the direction in which white cloud 142 is seen is stronger than the light component incident from the direction in which blue sky 141 or black cloud 143 is seen.

[0021] 2A , when looking outside from lighting control area 100 through external light incident section 140, white cloud 142 is located to the right of blue sky 141 or black cloud 143. The light incident on external light incident section 140 from white cloud 142 is stronger than the light incident on external light incident section 140 from blue sky 141 or black cloud 143. Therefore, of the components of external light 50 in each direction, the component incident in a direction tilted from the right to the left with respect to external light incident section 140 is stronger.

[0022] 2A , when looking outside from the lighting control area 100 through the external light incident section 140, a black cloud 143 is located to the left of a blue sky 141. The light incident on the external light incident section 140 from the black cloud 143 is weaker than the light incident on the external light incident section 140 from the blue sky 141. In other words, of the components of external light 50 in each direction, the component incident in a direction tilted from the left side to the right side with respect to the external light incident section 140 is weak.

[0023] As described above, external light 50 has directionality. Directivity is a property that causes a distribution in the intensity of the components of external light 50 in each direction. If the intensity of the components of external light 50 in each direction is uniform, external light 50 does not have directionality. The directionality of external light 50 is determined according to the arrangement of objects visible from external light entrance section 140, such as blue sky 141, white clouds 142, or black clouds 143, which serve as light sources of external light 50.

[0024] The external light 50 may include direct sunlight. The lighting control device 10 according to the present disclosure estimates the directionality of the external light 50 excluding direct sunlight.

[0025] When external light 50, excluding direct sunlight, enters the lighting control area 100 through the external light incident section 140, the external light incident section 140 is approximated to a surface light source that emits the external light 50. In other words, the external light 50 is approximated to light emitted from a surface light source. The light emitted from a surface light source includes light traveling in various directions. The intensity of the light emitted from the surface light source and traveling in each direction has a distribution. The strongest light component of the light traveling in each direction is also referred to as the main component of the surface light source. The direction in which the main component of the surface light source travels is also referred to as the main direction of the surface light source. The strongest light component of the light traveling in each direction of the external light 50 is also referred to as the main component of the external light 50. The direction in which the main component of the external light 50 travels is also referred to as the main direction of the external light 50.

[0026] The main direction of the surface light source may be a direction that coincides with the normal direction of the light exit surface of the surface light source. The main direction of the surface light source may be a direction that has an angle with the normal direction of the exit surface. The directionality of the external light 50 is expressed as the main direction of the surface light source that approximates the external light 50.

[0027] The lighting control device 10 estimates the directionality of external light 50 based on the measurement results of the brightness measurement device 20 in the lighting-controlled area 100 illustrated in Figures 2A, 2B, and 2C. The lighting control device 10 estimates the brightness caused by the external light 50 in the lighting-controlled area 100 based on the estimation results of the directionality of the external light 50. The lighting control device 10 determines the intensity of the illumination light 60 to be emitted by the lighting device 40, i.e., the output of the lighting device 40, so as to control the combined brightness of the brightness caused by the external light 50 and the brightness caused by the illumination light 60 in the lighting-controlled area 100.

[0028] An example of the configuration of each part of the lighting control system 1 will be described below.

[0029] <Lighting Control Device 10> As shown in FIG. 1 , the lighting control device 10 includes an acquisition unit 12, an estimation unit 14, and a control unit 16.

[0030] The acquisition unit 12 acquires the measurement results of the brightness measurement device 20. The acquisition unit 12 may be configured to be able to communicate with the brightness measurement device 20 based on various communication standards such as a LAN (Local Area Network) or RS-232C or RS-485. The acquisition unit 12 may be configured to be able to communicate with the brightness measurement device 20 via a wired or wireless connection.

[0031] The estimation unit 14 estimates the brightness of the illumination-controlled area 100 based on the measurement result of the brightness measurement device 20. The control unit 16 determines the intensity of the illumination light 60 to be emitted by the illumination device 40 based on the estimation result of the brightness of the illumination-controlled area 100, and controls the illumination device 40.

[0032] The estimation unit 14 or the control unit 16 may include at least one processor. The processor may execute a program that implements the functions of the estimation unit 14 or the control unit 16. The processor may be implemented as a single integrated circuit or a discrete circuit. The processor may be implemented as multiple communicatively connected integrated circuits or discrete circuits. The processor may also be implemented based on various other known technologies.

[0033] The lighting control device 10 may further include a memory unit. The memory unit may include, for example, an electromagnetic storage medium such as a magnetic disk, or may include a memory such as a semiconductor memory or a magnetic memory. The memory unit may store various information referenced in the operation of the estimation unit 14 or the control unit 16, and programs that implement various functions of the estimation unit 14 or the control unit 16. The memory unit may function as a work memory for the estimation unit 14 or the control unit 16. The memory unit may be configured integrally with the estimation unit 14 or the control unit 16, or may be configured separately from the estimation unit 14 or the control unit 16.

[0034] The control unit 16 outputs information for controlling the lighting device 40 to the lighting device 40. The control unit 16 may be configured to be able to communicate with the lighting device 40 based on various communication standards such as LAN, RS-232C, or RS-485. The control unit 16 may be configured to be able to communicate with the lighting device 40 via wired or wireless communication. In the control unit 16, a portion that generates information for controlling the lighting device 40 and a portion that communicates with the lighting device 40 may be configured separately.

[0035] The acquisition unit 12, the estimation unit 14, and the control unit 16 may be configured integrally. The acquisition unit 12 and the estimation unit 14 may be configured integrally. The estimation unit 14 and the control unit 16 may be configured integrally.

[0036] The lighting control device 10 may further include an input device that accepts input of information, data, etc. from a user. The input device may include, for example, a touch panel or touch sensor, or a pointing device such as a mouse. The input device may include physical keys. The input device may include an audio input device such as a microphone. The lighting control device 10 may be configured to be connectable to an external input device.

[0037] The lighting control device 10 may further include an output device that outputs information, data, or the like to a user. The output device may include, for example, a display device that outputs visual information such as images, characters, or graphics. The display device may include, for example, a liquid crystal display (LCD), an organic electroluminescence (EL) display, an inorganic electroluminescence (EL) display, or a plasma display panel (PDP). The display device is not limited to these displays and may include various other display types. The display device may include a light-emitting device such as an LED (light-emitting diode) or an LD (laser diode). The display device may include various other devices. The output device may include, for example, an audio output device such as a speaker that outputs auditory information such as sound. The output device may include, for example, a vibration device such as a vibrator that outputs tactile information such as vibration. The output device is not limited to these examples and may include various other devices. The lighting control device 10 may be configured to be connectable to an external output device.

[0038] The part of the lighting control device 10 that estimates the directionality of extraneous light 50 or the brightness of the lighting control device 10 due to extraneous light 50 is also referred to as an estimation device. The estimation device includes the estimation unit 14 of the lighting control device 10. The estimation device may also include the acquisition unit 12 of the lighting control device 10. The estimation device may be configured as a separate entity from the lighting control device 10.

[0039] <Illumination Device 40> The illumination device 40 emits illumination light 60. The illumination device 40 includes various light sources such as LEDs. The illumination device 40 may be configured as a glareless light. The illumination device 40 is not limited to being a glareless light and may be configured in various other ways.

[0040] The number of lighting devices 40 installed in the lighting control area 100 is not limited to one and may be two or more. When multiple lighting devices 40 are installed in the lighting control area 100, the lighting control device 10 may individually control the on / off state of each lighting device 40. Furthermore, the lighting control device 10 may individually set the intensity of the illumination light 60 emitted by each lighting device 40.

[0041] <Brightness measuring device 20> The brightness measuring device 20 measures the brightness of a measurement point 80 (see FIG. 2B or FIG. 2C ) located in the lighting control area 100. The brighter the measurement point 80, the stronger the light reflected or scattered from the measurement point 80. The brightness measuring device 20 may measure the intensity of light reflected or scattered from the measurement point 80 and incident on the brightness measuring device 20 as the brightness of the measurement point 80.

[0042] The brightness measurement device 20 may be configured to include an illuminance sensor that measures the illuminance at the measurement point 80. The brightness measurement device 20 may measure the illuminance at the measurement point 80 as the brightness at the measurement point 80. Illuminance is the amount of luminous flux incident on a unit area.

[0043] The brightness measurement device 20 may be configured to include an image sensor that captures an image of the measurement point 80. The brightness measurement device 20 may measure a value calculated from a luminance signal Y of an image captured by the image sensor in YUV format of the measurement point 80 as the brightness or illuminance of the measurement point 80. The image sensor may include a CCD (Charge Coupled Device Image Sensor) or a CMOS (Complementary Metal Oxide Semiconductor) sensor, etc.

[0044] (Example of Operation of Lighting Control System 1) As described above, external light 50 has directionality. The directionality of external light 50 affects the distribution of brightness in lighting-controlled area 100 caused by external light 50.

[0045] In lighting control system 1, lighting control device 10 utilizes the fact that the directionality of external light 50 affects the brightness distribution caused by external light 50, and estimates the directionality of external light 50 based on brightness measurement results at at least two measurement points 80 located in lighting control area 100. Lighting control device 10 can estimate the directionality of external light 50 without measuring the brightness distribution of the entire lighting control area 100. As a result, the configuration for measuring brightness can be simplified.

[0046] Based on the estimated directionality of the external light 50, the lighting control device 10 estimates the brightness caused by the external light 50 at points other than the measurement point 80. The lighting control device 10 sets the intensity of the illumination light 60 emitted by the lighting device 40 so as to control the combined brightness of the brightness caused by the external light 50 and the brightness caused by the illumination light 60 in the lighting-controlled area 100. In other words, the lighting control device 10 can estimate the brightness caused by the external light 50 in the entire lighting-controlled area 100 from the brightness measurement results of at least two measurement points 80 in the lighting-controlled area 100. As a result, the configuration for measuring brightness can be simplified.

[0047] <Estimation of Directionality of Extraneous Light 50> The operation of estimating the directionality of extraneous light 50 will be described below. Extraneous light 50 is assumed to be approximated by light emitted from a surface light source. In other words, extraneous light incident unit 140 is approximated by a surface light source. Lighting control device 10 estimates the main direction of the surface light source as the directionality of extraneous light 50.

[0048] The lighting control device 10 can calculate the intensity of light incident from each point on the emission surface of the surface light source to any point in the lighting control area 100 based on the main direction and light intensity of the surface light source that approximates the external light incident unit 140. The integrated value of the intensities of light incident from all points on the emission surface of the surface light source to any point represents the intensity of light incident from the entire surface light source to the any point. The intensity of light incident from the entire surface light source that approximates the external light incident unit 140 corresponds to the brightness caused by external light 50.

[0049] As illustrated in FIG. 3 , light incident on the lighting control area 100 from each point on the emission surface of the surface light source includes a main component represented by a solid line traveling in a main direction from each point on the emission surface of the surface light source, and a component represented by a dashed line traveling from each point on the emission surface of the surface light source toward an arbitrary point. In FIG. 3 , an arbitrary point for which the lighting control device 10 estimates brightness is represented as an estimated point 70. The lighting control device 10 can calculate the intensity of light incident on the estimated point 70 from the entire external light incident unit 140 by calculating the sum of the light intensities of the components represented by the solid lines that enter the estimated point 70 from each point on the external light incident unit 140, which is approximated to a surface light source. The intensity of light incident on the estimated point 70 from the entire external light incident unit 140 corresponds to the brightness of the estimated point 70.

[0050] In the present disclosure, the relationship between the main direction of a surface light source and the intensity of light incident from each point on the emission surface of the surface light source to an estimated point 70 in the lighting control area 100 is represented by a ray volume model. In the ray volume model, the intensity of light incident from an arbitrary point on the emission surface of the surface light source to an estimated point 70 away from the surface light source is determined according to the positional relationship between the arbitrary point on the emission surface of the surface light source and the estimated point 70. A method using a ray volume model will be described below as a method for estimating brightness due to external light at a specified estimated point.

[0051] The distribution of the intensity of light emitted in each direction from an arbitrary point on the emission surface of a surface light source is approximated by an ellipse on a plane including the principal direction of the surface light source, with the principal direction of the surface light source being its major axis. The degree of flattening of the ellipse may be expressed by a form factor. The sharper the directionality of the light emitted from the surface light source, the closer the value of the form factor is set to 0.

[0052] When the distribution of the intensity of light emitted in each direction from a surface light source is approximated by an ellipse on a plane including the main direction of the surface light source, the intensity of the light component incident on the estimated point 70 from each point of the surface light source changes depending on the angle between the traveling direction of the component and the main direction of the surface light source. Specifically, the greater the angle between the traveling direction of the light component and the main direction of the surface light source, the smaller the intensity of the light component.

[0053] When calculating the intensity of a component of light incident on estimated point 70 from an arbitrary point on external light incident section 140 that approximates a surface light source, lighting control device 10 can calculate the intensity of the component to be calculated by multiplying the intensity of the main component of the surface light source by a coefficient determined according to the angle between the traveling direction of the component to be calculated and the main direction of the surface light source. Lighting control device 10 may appropriately determine the coefficient determined according to the angle between the traveling direction of the component to be calculated and the main direction of the surface light source according to the ray volume model.

[0054] The intensity of light incident on the estimated point 70 from any point on the emission surface of the surface light source is inversely proportional to the square of the distance that the light travels. In other words, the intensity of the light component incident on the estimated point 70 from each point on the external light incident unit 140, which is approximated to a surface light source, is inversely proportional to the square of the distance from each point on the external light incident unit 140 to the estimated point 70.

[0055] Here, the angle between the traveling direction of the light component incident on estimated point 70 and the main direction of the surface light source is represented by θ. The distance the light component incident on estimated point 70 travels from external light incident unit 140 to estimated point 70 is calculated as the value obtained by multiplying the distance the main component of the surface light source travels to estimated point 70 by 1 / cos θ. Then, lighting control device 10 can calculate the intensity of the component traveling in a direction whose angle from the main direction of the surface light source is represented by θ when it enters estimated point 70, as the value obtained by multiplying the intensity of the main component of the surface light source when it enters estimated point 70 by the square of cos θ.

[0056] As described above, the lighting control device 10 can calculate the intensity of components traveling from each point on the external light incident unit 140, which is approximated to a surface light source, to the estimated point 70 when they are incident on the estimated point 70, taking into account the direction and distance of light travel. In the ray volume model, the intensity of light incident on the estimated point 70 is the sum of the intensities of light incident on the estimated point 70 from each point on the emission surface of the surface light source. The intensity of light incident on the estimated point 70 corresponds to the brightness of the estimated point 70. Therefore, the lighting control device 10 can calculate the brightness attributable to external light 50 at the estimated point 70 by summing, across the entire external light incident unit 140, the calculation results of the intensities of components incident on the estimated point 70 from each point on the external light incident unit 140.

[0057] By performing the reverse calculation to calculate the brightness of the estimated point 70 in the lighting control area 100 based on the main direction of the external light 50, the main direction of the external light 50 can be estimated based on the measurement results of the brightness of the measurement point 80 located in the lighting control area 100.

[0058] The main direction of the external light 50 is determined by the angle with respect to the normal direction of the emission surface of a surface light source that approximates the external light incident section 140. In the present disclosure, the emission surface of the surface light source that approximates the external light incident section 140 is assumed to be a plane that includes the vertical direction. When the emission surface of the surface light source is a plane that includes the vertical direction, the normal direction of the emission surface of the surface light source is a direction perpendicular to the vertical direction, i.e., the horizontal direction. The horizontal direction is a direction included in a horizontal plane that is perpendicular to the vertical direction.

[0059] The main direction of the external light 50 may be specified by a horizontal angle and a vertical angle. The horizontal angle is the angle with respect to the normal direction of the emission surface of the surface light source when the main direction of the external light 50 is projected onto a horizontal plane, and is the angle θ between the dashed line representing the normal direction and the arrow of the main direction of the external light 50 in FIG. 2C . Ｈ The vertical angle is an angle with respect to the horizontal plane, and is the angle θ between the dashed line representing the horizontal plane in FIG. 2B and the arrow indicating the main direction of the external light 50. Ｖ It is expressed as:

[0060] The lighting control system 1 according to the present disclosure may use a brightness measurement device 20 (see FIG. 2B or FIG. 2C) to measure the brightness at measurement points 81 to 88 located as illustrated in FIG. 4 in the lighting control area 100. When there is no need to distinguish between the measurement points 81 to 88, they will be collectively referred to as measurement point 80 (see FIGS. 2B and 2C).

[0061] The measurement points 81, 82, and 83 are aligned in a row along the external light entrance portion 140 on the floor 120 of the lighting control area 100. The group including the measurement points 81, 82, and 83 is also referred to as a first group.

[0062] The measurement points 84, 85, and 86 are aligned in a row along the external light entrance portion 140 on the floor 120 of the lighting control area 100. The group including the measurement points 84, 85, and 86 is located farther from the external light entrance portion 140 than the first group, and is also referred to as the second group.

[0063] The measurement points 87 and 88 are located on the floor 120 of the lighting control area 100 farther from the external light entrance portion 140 than the points in the second group. The group including the measurement points 87 and 88 is also referred to as the third group.

[0064] Below, a procedure for estimating the main direction of external light 50 will be described, assuming that only external light 50 is incident on lighting-controlled area 100. In other words, a procedure for estimating the main direction of external light 50 will be described when lighting devices 40 installed in lighting-controlled area 100 are turned off and are not emitting illumination light 60.

[0065] <<Estimation of horizontal angle>> If the direction of the main direction of the external light 50 when projected onto a horizontal plane is inclined with respect to the normal direction of the emission surface of the surface light source, that is, if the horizontal angle of the main direction of the external light 50 is not 0 degrees, the brightness caused by the external light 50 may differ at each of the multiple measurement points 80 lined up in a direction along the external light incident section 140.

[0066] As illustrated in FIG. 5 , it is assumed that, in a plan view of the floor 120 of the lighting-controlled area 100, the measurement points 81, 82, and 83 of the first group are arranged side by side from top to bottom, and the main direction of the external light 50 is tilted downward. In this case, the main component of the external light 50 cannot be incident on the measurement point 81 located above. On the other hand, the main component of the external light 50 can be incident on the measurement point 83 located below. In this case, the measurement point 83 can be brighter than the measurement point 81. Furthermore, the difference in brightness between the measurement point 81 and the measurement point 83 can change depending on the horizontal angle of the main component of the external light 50.

[0067] The lighting control device 10 may acquire brightness measurement results for each of the measurement points 81 and 83 using the acquisition unit 12, and may estimate the horizontal angle of the main direction of the external light 50 using the estimation unit 14 based on the magnitude of the difference between the brightness measurement result for the measurement point 81 and the brightness measurement result for the measurement point 83. The lighting control device 10 may further acquire brightness measurement results for the measurement point 82 using the acquisition unit 12, and may estimate the horizontal angle of the main direction of the external light 50 based further on the brightness measurement result for the measurement point 82 using the estimation unit 14.

[0068] The first group is not limited to the measurement points 81, 82, and 83, and may include other measurement points 80 positioned side by side in a direction along the external light incident section 140. The acquisition unit 12 may acquire brightness measurement results of at least two measurement points 80 among the plurality of measurement points 80 in the first group. The estimation unit 14 may estimate the horizontal angle of the main direction of the external light 50 based on the brightness measurement results of at least two measurement points 80 among the plurality of measurement points 80 in the first group.

[0069] As illustrated in FIG. 5 , it is assumed that in a plan view of the floor 120 of the lighting-controlled area 100, in addition to the first group, measurement points 84, 85, and 86 of the second group are positioned side by side from top to bottom. In this case, depending on the inclination of the main component of the external light 50, the brightness of two measurement points 80 aligned in the normal direction to the emission surface of a surface light source approximating the external light incident section 140 may differ. Specifically, the brightness of measurement point 81 may differ from the brightness of measurement point 84. Furthermore, the brightness of measurement point 82 may differ from the brightness of measurement point 85. Furthermore, the brightness of measurement point 83 may differ from the brightness of measurement point 86.

[0070] Acquisition unit 12 of lighting control device 10 may acquire the brightness measurement results of measurement point 84, 85, or 86. When acquisition unit 12 acquires the brightness measurement results of measurement point 81 and measurement point 84, estimation unit 14 of lighting control device 10 may estimate the horizontal angle of the main direction of external light 50 further based on the magnitude of the difference between the brightness measurement results of measurement point 81 and measurement point 84.

[0071] The estimation unit 14 may correct the result of estimating the horizontal angle of the main direction of the external light 50 based on the brightness measurement results of the measurement points 80 of the first group based on the brightness measurement results of the measurement points 80 of the second group.

[0072] <<Estimation of Vertical Angle>> The greater the downward inclination of the main direction of the external light 50 with respect to the normal to the emission surface of the surface light source, the shorter the distance that the external light 50 reaches within the illumination-controlled area 100. As a result, the greater the vertical angle of the main direction of the external light 50, the weaker the brightness caused by the external light 50 at points farther from the external light incident section 140 in the illumination-controlled area 100. In other words, the brightness caused by the external light 50 may differ at each of the multiple measurement points 80 lined up in a direction away from the external light incident section 140.

[0073] 6 , in a cross-sectional view of the lighting control area 100, it is assumed that the first group of measurement points 82 and the second group of measurement points 85 are positioned side by side in a direction away from the external light incident section 140, and the main direction of the external light 50 is tilted downward. In this case, the main component of the external light 50 is incident on the first group of measurement points 82 that are close to the external light incident section 140, but cannot be incident on the second group of measurement points 85 that are far from the external light incident section 140. In this case, the measurement point 82 may be brighter than the measurement point 85. Furthermore, the difference in brightness between the measurement point 82 and the measurement point 85 may vary depending on the vertical angle of the main component of the external light 50.

[0074] The lighting control device 10 may acquire the brightness measurement results of each of the measurement points 82 and 85 using the acquisition unit 12, and estimate the vertical angle of the main direction of the external light 50 based on the magnitude of the difference between the brightness measurement result of the measurement point 82 and the brightness measurement result of the measurement point 85 using the estimation unit 14.

[0075] The measurement point 82 is also referred to as a first point. The measurement point 85 is also referred to as a second point. The second point, i.e., the measurement point 85, is located farther from the external light incident unit 140 than the first point, i.e., the measurement point 82. The estimation unit 14 may estimate the vertical angle of the main direction of the external light 50 based on the brightness measurement results of each of the first and second points.

[0076] The acquisition unit 12 may acquire brightness measurement results not only for measurement point 82 in the first group but also for other points, such as measurement point 81 or 83. When the acquisition unit 12 acquires the brightness measurement result for measurement point 81 in the first group, the acquisition unit 12 may acquire the brightness measurement result for measurement point 84 in the second group, which is located in the normal direction of the external light incident unit 140 relative to measurement point 81 in the first group. In other words, the acquisition unit 12 may select points from each of the first and second groups that are aligned in the normal direction of the external light incident unit 140, and acquire the brightness measurement results for the selected points. The estimation unit 14 may estimate the perpendicular angle of the principal direction of the external light 50 based on the brightness measurement result for at least one point in the first group and the brightness measurement result for at least one point in the second group. Of the points at which the estimation unit 14 measures brightness to estimate the perpendicular angle of the principal direction of the external light 50, the number of points in the second group may be smaller than the number of points in the first group.

[0077] The acquisition unit 12 may acquire brightness measurement results of a third group of measurement points 80 that are farther from the external light incident unit 140 than the second group. The estimation unit 14 may correct the result of estimating the vertical angle of the main direction of the external light 50 based on the brightness measurement results of the measurement points 80 of the first and second groups, based on the brightness measurement results of the measurement points 80 of the third group. When the acquisition unit 12 acquires brightness measurement results of the measurement points 80 of the third group, the estimation unit 14 may estimate the vertical angle of the main direction of the external light 50 based on the brightness measurement results of the measurement points 80 of the first group and the brightness measurement results of the third group. The estimation unit 14 may estimate the vertical angle of the main direction of the external light 50 based on the brightness measurement results of the measurement points 80 of the second group and the brightness measurement results of the third group. Of the points whose brightness the estimation unit 14 measures to estimate the vertical angle of the main direction of the external light 50, the number of points in the third group may be smaller than the number of points in the first group.

[0078] The points in the first group, the second group, and the third group selected by the acquisition unit 12 do not have to be aligned in the normal direction of the external light incident unit 140. The acquisition unit 12 may acquire brightness measurement results of at least two points that are at different distances from the external light incident unit 140 along the direction when the main direction of the external light 50 is projected onto a horizontal plane in a plan view of the lighting control area 100.

[0079] <<Estimation Taking Influence of Illumination Light 60 In the procedure described above, the brightness at each point in the lighting-controlled area 100 is calculated as the brightness due only to external light 50. When the lighting devices 40 installed in the lighting-controlled area 100 emit illumination light 60, the brightness at each point in the lighting-controlled area 100 is the combined brightness of the brightness due to external light 50 and the brightness due to illumination light 60.

[0080] The estimation unit 14 of the lighting control device 10 calculates a value by subtracting the brightness attributable to the illumination light 60 from the brightness measurement results at each point in the lighting control area 100 acquired by the acquisition unit 12. In other words, the estimation unit 14 may remove the component attributable to the illumination light 60 from the brightness at each point in the lighting control area 100. The estimation unit 14 may regard the brightness from which the component attributable to the illumination light 60 has been removed as the brightness attributable to the external light 50, and estimate the main direction of the external light 50.

[0081] The estimation unit 14 may calculate the brightness at each point caused by the illumination light 60 based on the installation position of the illumination device 40 and the output of the illumination device 40. The output of the illumination device 40 may be expressed as the intensity of the illumination light 60 emitted from the illumination device 40. The output of the illumination device 40 may be expressed as the power input to the illumination device 40.

[0082] Specifically, the estimation unit 14 may calculate the intensity of the illumination light 60 emitted in each direction from the illumination device 40 based on the output of the illumination device 40. When one illumination device 40 is installed in the illumination-controlled area 100, the estimation unit 14 may calculate the intensity of the illumination light 60 incident from one illumination device 40 to each point in the illumination-controlled area 100 as the brightness attributable to the illumination light 60 at each point. In other words, the estimation unit 14 can calculate the distribution of brightness attributable to the illumination light 60 emitted from one illumination device 40.

[0083] When a plurality of lighting devices 40 are installed in the lighting control area 100, the estimation unit 14 may calculate the sum of the intensities of the illumination light 60 incident on an arbitrary point from the plurality of lighting devices 40 by calculating and summing the intensities of the components of the illumination light 60 incident on the arbitrary point from each lighting device 40. The estimation unit 14 may calculate the sum of the intensities of the illumination light 60 incident on the arbitrary point as the brightness caused by the illumination light 60 at the arbitrary point. The estimation unit 14 can calculate the brightness caused by the illumination light 60 at each point of the lighting control area 100 by calculating the sum of the intensities of the illumination light 60 incident on the arbitrary point at each point of the lighting control area 100. In other words, the estimation unit 14 can calculate the distribution of brightness caused by the illumination light 60 emitted from the plurality of lighting devices 40.

[0084] The estimation unit 14 may calculate the intensity of the illumination light 60 by assuming that the intensity of the components of the illumination light 60 emitted from the lighting device 40 is uniform in each direction. In other words, the estimation unit 14 may assume that the illumination light 60 emitted from the lighting device 40 does not have directionality. The estimation unit 14 may calculate the brightness caused by the illumination light 60 by taking into account the directionality of the illumination light 60 emitted from the lighting device 40.

[0085] <<Summary of Estimation of Directionality of Extraneous Light 50>> As described above, the estimation unit 14 can estimate the main direction of the extraneous light 50. The estimation unit 14 may estimate both the horizontal angle and the vertical angle of the main direction of the extraneous light 50. The estimation unit 14 may estimate only the horizontal angle of the main direction of the extraneous light 50. The estimation unit 14 may estimate only the vertical angle of the main direction of the extraneous light 50.

[0086] <Estimation of brightness caused by external light 50> The estimation unit 14 of the lighting control device 10 can estimate the brightness caused by external light 50 at any point in the lighting control area 100 based on the estimation result of the main direction of the external light 50. The estimation unit 14 may estimate the distribution of brightness caused by external light 50 in the lighting control area 100 by estimating the brightness caused by external light 50 at a plurality of points in the lighting control area 100.

[0087] Specifically, the estimation unit 14 uses the above-described ray volume model to calculate the intensity of light traveling in each direction from each point on the external light incident unit 140, based on the main direction of the external light 50. The estimation unit 14 identifies the components of light that are incident on an arbitrary point on the illumination control area 100 from each point on the external light incident unit 140, and calculates the intensity of light that is incident on an arbitrary point on the illumination control area 100 by summing the intensities of the identified light components.

[0088] The estimation unit 14 may output the calculation result of the intensity of light incident on an arbitrary point in the lighting-controlled area 100 as an estimation result of the brightness at the arbitrary point in the lighting-controlled area 100. The estimation unit 14 may set a conversion coefficient specifying the relationship between light intensity and brightness, and output a value obtained by multiplying the value of the calculation result of the intensity of light incident on the arbitrary point by the conversion coefficient as an estimation value of the brightness at the arbitrary point. The estimation unit 14 may output the value of the calculation result of the intensity of light incident on the arbitrary point as is as the estimation value of the brightness at the arbitrary point.

[0089] As described above, the estimation unit 14 may estimate both the horizontal angle and the vertical angle of the main direction of the external light 50. In this case, the estimation unit 14 may calculate the brightness distribution in the direction along the external light incident section 140 based on the estimation result of the horizontal angle, and may calculate the brightness distribution in the normal direction of the external light incident section 140 based on the estimation result of the vertical angle.

[0090] As described above, the estimation unit 14 may estimate only the horizontal angle of the main direction of the external light 50. In this case, the estimation unit 14 may calculate the brightness distribution in a direction along the emission surface of a surface light source that approximates the external light incident unit 140 based on the estimation result of the horizontal angle. The estimation unit 14 may calculate the brightness distribution in the normal direction of the external light incident unit 140 using a value that is set in advance as the vertical angle. The estimation unit 14 may use, for example, a value that is set depending on the altitude of the sun or the environment outside the external light incident unit 140 as the vertical angle.

[0091] As described above, the estimation unit 14 may estimate only the vertical angle of the main direction of the external light 50. In this case, the estimation unit 14 may calculate the brightness distribution in the normal direction of the external light incident unit 140 based on the result of estimating the vertical angle. The estimation unit 14 may use a value set in advance as the horizontal angle to calculate the brightness distribution in a direction along the emission surface of a surface light source that approximates the external light incident unit 140. The estimation unit 14 may use, for example, a value set in accordance with the direction of the sun or the environment outside the external light incident unit 140 as the horizontal angle.

[0092] <Control of lighting device 40> The control unit 16 of the lighting control device 10 controls the lighting device 40 based on the estimation result of the brightness of the lighting control area 100 estimated by the estimation unit 14. The control unit 16 may control the on / off state of the lighting device 40. The control unit 16 may also control the intensity of the illumination light 60 output when the lighting device 40 is on.

[0093] The control unit 16 may set a brightness control target for each point in the lighting control area 100, and determine the output of the lighting device 40 so that the difference between the brightness control target and the estimated brightness caused by external light 50 is compensated for with the brightness caused by the illumination light 60.

[0094] The control unit 16 may set the brightness control target so as to uniformly distribute brightness in the illumination-controlled area 100. The control unit 16 may also set the brightness control target so as to brighten only a specific area in the illumination-controlled area 100.

[0095] The control unit 16 may set the area to be brightened as an area in the lighting controlled area 100 where a person is present. The control unit 16 may acquire the area in the lighting controlled area 100 where a person is present based on information from a motion sensor or a camera installed in the lighting controlled area 100. The lighting control system 1 may include a device capable of detecting the position of a person in the lighting controlled area 100.

[0096] The control unit 16 determines the output of the lighting device 40 so as to control the brightness caused by the illumination light 60 at each point in the lighting control area 100. The output of the lighting device 40 may be expressed as the intensity of the illumination light 60 emitted from the lighting device 40. The output of the lighting device 40 may be expressed as the power input to the lighting device 40.

[0097] Specifically, the control unit 16 may calculate the intensity of the illumination light 60 that needs to be incident on each point in the illumination control area 100 so that the brightness caused by the illumination light 60 at each point matches the control target.

[0098] On the other hand, the control unit 16 may calculate the intensity of the illumination light 60 incident on each point in the lighting control area 100 from each of the multiple lighting devices 40 installed in the lighting control area 100, based on the distribution of the components of the illumination light 60 emitted toward each point in the lighting control area 100 by each of the multiple lighting devices 40 installed in the lighting control area 100, i.e., the directionality of the illumination light 60, using a mathematical formula that includes the output of each lighting device 40 as a parameter.

[0099] The control unit 16 may generate a mathematical formula for calculating the sum of the intensities of the components of the illumination light 60 incident from each lighting device 40 for each point in the lighting control area 100. The control unit 16 may generate an evaluation function that outputs the difference between a value calculated by the mathematical formula generated for each point in the lighting control area 100 and the intensity of the illumination light 60 that needs to be incident on each point in the lighting control area 100, and may determine the output of each lighting device 40 by solving a linear programming problem that minimizes the value of the evaluation function. In order to achieve power savings for the lighting devices 40, the evaluation function may include a term for the sum of the outputs of the lighting devices 40.

[0100] The control unit 16 may determine the output of the lighting device 40 using various other methods, not limited to the method based on the evaluation function described above.

[0101] <Example of information flow in lighting control system 1> The lighting control system 1 can control the brightness of the lighting control area 100 through mutual cooperation between the lighting control device 10, brightness measurement device 20, and lighting device 40. The flow of information between the lighting control device 10, brightness measurement device 20, and lighting device 40 in the lighting control system 1 will be described below with reference to Figure 7.

[0102] The brightness measuring device 20 outputs the brightness measurement values ​​at the measurement points 80 of the first group to the lighting control device 10. The brightness measuring device 20 outputs the brightness measurement values ​​at the measurement points 80 of the second group to the lighting control device 10. The brightness measurement result by the brightness measuring device 20 is the combined brightness of the brightness caused by extraneous light 50 and the brightness caused by illumination light 60.

[0103] The lighting device 40 outputs the brightness resulting from the illumination light 60 emitted by the lighting device 40 to the lighting control device 10. The lighting device 40 may also output a setting value for the intensity of the illumination light 60 emitted by the lighting device 40 to the lighting control device 10.

[0104] The lighting control device 10 calculates the brightness caused by extraneous light 50 at the measurement points 80 of the first group by subtracting the brightness caused by the illumination light 60 from the measured brightness values ​​at the measurement points 80 of the first group. The lighting control device 10 calculates the brightness caused by extraneous light 50 at the measurement points 80 of the second group by subtracting the brightness caused by the illumination light 60 from the measured brightness values ​​at the measurement points 80 of the second group. When the lighting control device 10 acquires the set value of the intensity of the illumination light 60 from the lighting device 40, it calculates the brightness caused by the illumination light 60 at each measurement point 80 based on the set value of the intensity of the illumination light 60 and the directional characteristics of the illumination light 60 emitted by the lighting device 40.

[0105] The lighting control device 10 may estimate the horizontal angle of the main direction of the extraneous light 50 based on the brightness attributable to the extraneous light 50 at the first group of measurement points 80 and the brightness attributable to the extraneous light 50 at the second group of measurement points 80. The lighting control device 10 may estimate the horizontal angle of the main direction of the extraneous light 50 based only on the brightness attributable to the extraneous light 50 at the first group of measurement points 80.

[0106] The lighting control device 10 may estimate the vertical angle of the principal direction of the external light 50 based on the brightness attributable to the external light 50 at the first group of measurement points 80 and the brightness attributable to the external light 50 at the second group of measurement points 80. The lighting control device 10 may estimate the vertical angle of the principal direction of the external light 50 further based on the estimation result of the horizontal angle of the principal direction of the external light 50.

[0107] The lighting control device 10 estimates the distribution of brightness caused by the external light 50 at points other than the measurement point 80 in the lighting-controlled area 100 based on at least one of the horizontal angle and vertical angle of the main direction of the external light 50. Based on the distribution of brightness caused by the external light 50 in the lighting-controlled area 100, the lighting control device 10 determines the output of the lighting device 40 so as to control the brightness at each point in the lighting-controlled area 100, and outputs the output to the lighting device 40. The lighting device 40 emits illumination light 60 based on the output determined by the lighting control device 10.

[0108] As described above, in lighting control system 1, the brightness of lighting-controlled area 100 is controlled by information flowing between lighting control device 10, brightness measurement device 20, and lighting device 40. By repeatedly estimating the brightness caused by external light 50, lighting control system 1 can control lighting device 40 to maintain the brightness of lighting-controlled area 100 even when the intensity of external light 50 changes.

[0109] The brightness measurement device 20 may output the brightness measurement values ​​at the third group of measurement points 80 to the lighting control device 10. The lighting control device 10 may calculate the brightness attributable to extraneous light 50 at the third group of measurement points 80 from the brightness measurement values ​​at the third group of measurement points 80. The lighting control device 10 may estimate the vertical angle of the main direction of extraneous light 50 based further on the brightness attributable to extraneous light 50 at the third group of measurement points 80.

[0110] <Example of Procedure of Estimation Method> The estimation unit 14 of the lighting control device 10 may execute an estimation method including the steps of the flowchart illustrated in Fig. 8. The estimation method may be realized as an estimation program executed by a processor constituting the estimation unit 14. The estimation program may be stored on a non-transitory computer-readable medium.

[0111] The estimation unit 14 acquires the brightness measurement result at the measurement point 80 located in the illumination control area 100 from the brightness measurement device 20 (step S1).

[0112] The estimation unit 14 removes the component attributable to illumination from the brightness measurement result at the measurement point 80 (step S2). Specifically, the estimation unit 14 acquires information about the output of the lighting device 40, calculates the brightness attributable to illumination light 60, and removes the component attributable to illumination by subtracting the brightness attributable to illumination light 60 from the brightness measurement result at the measurement point 80. The value calculated by removing the component attributable to illumination from the brightness measurement result at the measurement point 80 corresponds to the brightness attributable to external light 50 at the measurement point 80.

[0113] The estimation unit 14 estimates the main direction of the external light 50 based on the brightness caused by the external light 50 at the measurement point 80 (step S3). The estimation unit 14 may estimate both the horizontal angle and the vertical angle of the main direction of the external light 50. The estimation unit 14 may estimate only the horizontal angle or only the vertical angle of the main direction of the external light 50.

[0114] The estimation unit 14 estimates the brightness caused by the extraneous light 50 at points other than the measurement point 80 in the lighting control area 100 (step S4). The estimation unit 14 may output the estimation results of the brightness at each point in the lighting control area 100 to the control unit 16. After performing the procedure of step S4, the estimation unit 14 ends the execution of the procedure of the flowchart in Fig. 8. The estimation unit 14 may repeatedly perform the procedure from steps S1 to S4. The estimation unit 14 may output the estimation result of the main direction of the extraneous light 50 after step S3.

[0115] <Example of Procedure of Lighting Control Method> Controller 16 of lighting control device 10 may execute a lighting control method including the procedure of the flowchart illustrated in Fig. 9. The lighting control method may be realized as a lighting control program executed by a processor constituting controller 16. The lighting control program may be stored on a non-transitory computer-readable medium.

[0116] The control unit 16 acquires from the estimation unit 14 the estimation result of the brightness caused by the external light 50 at each point in the illumination controlled area 100 (step S11).

[0117] Based on the estimation result of the brightness caused by external light 50 at each point in the illumination-controlled area 100, the control unit 16 determines the output of the illumination device 40 so as to control the brightness at each point in the illumination-controlled area 100 (step S12). The output of the illumination device 40 may be specified as the intensity of the illumination light 60 emitted by the illumination device 40. The output of the illumination device 40 may also be specified as the power input to the illumination device 40.

[0118] The control unit 16 controls the illumination device 40 based on the output of the illumination device 40 determined in step S12 (step S13). The illumination device 40 emits illumination light 60 at the output determined in step S12. After performing step S13, the control unit 16 ends the execution of the procedure of the flowchart in FIG. 9.

[0119] <Summary> As described above, the lighting control system 1 measures the brightness at at least two measurement points 80 in the lighting controlled area 100 using the brightness measurement device 20, and the lighting control device 10 can estimate the main direction of the external light 50. The lighting control device 10 can estimate the main direction of the external light 50 from only the brightness measurement results at the two measurement points 80. In other words, by simply obtaining the brightness measurement results at the two measurement points 80, the brightness distribution within the lighting controlled area 100, i.e., the room, can be estimated taking into account the directionality of the external light 50. As a result, the number of points at which brightness is measured can be minimized.

[0120] Furthermore, the lighting control system 1 can determine the output of the lighting devices 40 based on the estimated brightness distribution at each point in the lighting-controlled area 100. In other words, the brightness distribution of the entire lighting-controlled area 100 is controlled based on only the brightness measurement results at the two measurement points 80. As a result, the configuration for measuring brightness used to control the brightness distribution in the lighting-controlled area 100 is simplified.

[0121] The drawings illustrating the embodiments of the present disclosure are schematic, and the dimensional ratios and the like in the drawings do not necessarily correspond to the actual ones.

[0122] Those skilled in the art may make various modifications and alterations to the contents of the present disclosure based on the present disclosure. Therefore, these modifications and alterations are within the scope of the present disclosure. For example, in each embodiment, each functional unit, each means, or each step may be added to other embodiments without logical inconsistency, or may be replaced with each functional unit, each means, or each step of other embodiments. Furthermore, in each embodiment, multiple functional units, each means, or each step may be combined into one or divided into separate units. Furthermore, the above-described embodiments of the present disclosure are not limited to faithful implementation of each of the described embodiments, and may be implemented by combining features or omitting some features as appropriate.

[0123] In this disclosure, descriptions such as "first" and "second" are identifiers for distinguishing the configuration. In this disclosure, configurations distinguished by descriptions such as "first" and "second" can have their numbers exchanged. For example, the first group can exchange the identifiers "first" and "second" with the second group. The exchange of identifiers is performed simultaneously. The configurations remain distinguished even after the exchange of identifiers. Identifiers may be deleted. A configuration from which an identifier has been deleted is distinguished by a symbol. The descriptions of identifiers such as "first" and "second" in this disclosure should not be used solely to interpret the order of the configurations or to justify the existence of an identifier with a smaller number.

[0124] In one embodiment, (1) the estimation device includes an acquisition unit that acquires brightness measurement results of at least two points located in a lighting control area that is partitioned by a ceiling, a floor, and walls and has an external light entrance portion located on the wall, and an estimation unit that estimates a main direction of external light that enters from outside the lighting control area through the external light entrance portion based on the brightness measurement results of the at least two points.

[0125] (2) In the estimation device described in (1), the at least two points may include a first group including a plurality of points aligned along the external light incident portion on the floor, and the estimation unit may estimate a horizontal angle of the main direction of the external light based on a result of measuring brightness of each point in the first group.

[0126] (3) In the estimation device described in (2), the at least two points may include a second group including at least one point located farther from the external light incident unit than each of the points in the first group, and the estimation unit may estimate a horizontal angle of the main direction of the external light based on a result of measuring the brightness of each of the points in the second group.

[0127] (4) In the estimation device described in (3) above, the estimation unit may estimate the vertical angle of the main direction of the external light based on the brightness measurement result of at least one point in the first group and the brightness measurement result of at least one point in the second group.

[0128] (5) In the estimation device described in (4) above, the number of points in the second group may be smaller than the number of points in the first group.

[0129] (6) In the estimation device described in (3), the at least two points may include a third group including at least one point located farther from the external light incident unit than each of the points in the second group, and the estimation unit may estimate a vertical angle of the main direction of the external light based on a brightness measurement result of the at least one point in the first group and a brightness measurement result of the at least one point in the third group.

[0130] (7) In the estimation device described in (6) above, the number of points in the third group may be smaller than the number of points in the first group.

[0131] (8) In the estimation device described in (1), the at least two points may include a first point and a second point located farther from the external light incident unit than the first point. The estimation unit may estimate a vertical angle of the main direction of the external light based on brightness measurement results of the first point and the second point.

[0132] (9) In the estimation device described in any one of (1) to (8) above, the estimation unit may estimate the brightness of a point in the lighting control area that is different from the at least two points based on the estimation result of the main direction of the external light.

[0133] (10) In the estimation device described in (9) above, the estimation unit may estimate a brightness distribution within the illumination control area.

[0134] In one embodiment, (11) a lighting control device controls lighting devices installed in the lighting control area based on the brightness estimation result by the estimation device described in (9) or (10) above.

[0135] In one embodiment, (12) a lighting control system includes an estimation device according to any one of (1) to (10) above, a lighting control device according to claim 11, and a lighting device installed in the lighting control area.

[0136] In one embodiment, (13) an estimation method includes an estimation device obtaining brightness measurement results of at least two points located in a lighting control area partitioned by a ceiling, a floor, and walls and having an external light entrance portion located on the wall, and the estimation device estimating a main direction of external light entering from outside the lighting control area through the external light entrance portion based on the brightness measurement results of the at least two points.

[0137] In one embodiment, (14) the lighting control method includes a lighting control device controlling lighting devices installed in the lighting control area based on the brightness estimation result obtained by executing the estimation method described in (13) above.

[0138] In one embodiment, (15) the estimation program causes the estimation device to acquire brightness measurement results of at least two points located in a lighting control area that is partitioned by a ceiling, a floor, and walls and has an external light entrance portion located on the wall, and estimate a main direction of external light that enters from outside the lighting control area through the external light entrance portion based on the brightness measurement results of the at least two points.

[0139] In one embodiment, (16) the lighting control program causes the lighting control device to control the lighting devices installed in the lighting control area based on the brightness estimation result obtained by executing the estimation program described in (15) above.

[0140] 1 Lighting control system 10 Lighting control device (12: acquisition unit, 14: estimation unit, 16: control unit) 20 Brightness measurement device 40 Lighting device 50 External light (51: main component, 52: scattered component) 60 Illumination light 80-88 Measurement point 100 Lighting control area (110: ceiling, 120: floor, 130: wall, 140: external light incident part (141: blue sky, 142: white cloud, 143: black cloud)

Claims

1. An estimation device comprising: an acquisition unit that acquires measurement results of brightness at at least two points located in an illumination control area partitioned by a ceiling, a floor, and walls and having an external light incident portion located on the walls; and an estimation unit that estimates a main direction of external light incident through the external light incident portion from outside the illumination control area based on the measurement results of brightness at the at least two points.

2. The estimation device according to claim 1, wherein the at least two points include a first group including a plurality of points arranged along the external light incident portion on the floor, and the estimation unit estimates a horizontal angle of the main direction of the external light based on the measurement results of brightness at each point in the first group.

3. The estimation device according to claim 2, wherein the at least two points include a second group including at least one point located farther from the external light incident portion than each point in the first group, and the estimation unit further estimates a horizontal angle of the main direction of the external light based on the measurement results of brightness at each point in the second group.

4. The estimation device according to claim 3, wherein the estimation unit estimates a vertical angle of the main direction of the external light based on the measurement results of brightness at at least one point in the first group and the measurement results of brightness at at least one point in the second group.

5. The estimation device according to claim 4, wherein the number of points in the second group is less than the number of points in the first group.

6. The estimation device according to claim 3, wherein the at least two points include a third group including at least one point located farther from the external light incident portion than each point in the second group, and the estimation unit estimates a vertical angle of the main direction of the external light based on the measurement results of brightness at at least one point in the first group and the measurement results of brightness at at least one point in the third group.

7. The estimation device according to claim 6, wherein the number of points in the third group is less than the number of points in the first group.

8. The estimation device according to claim 1, wherein the at least two points include a first point and a second point located farther from the external light incident portion than the first point, and the estimation unit estimates a vertical angle of the main direction of the external light based on the measurement results of brightness at the first point and the second point respectively.

9. The estimation device according to any one of claims 1 to 8, wherein the estimation unit estimates the brightness of a point different from the at least two points in the illumination control area based on the estimation result of the main direction of the external light.

10. The estimation device according to claim 9, wherein the estimation unit estimates the brightness distribution in the illumination control area.

11. An illumination control device that controls an illumination device installed in the illumination control area based on the brightness estimation result by the estimation device according to claim 9 or 10.

12. An illumination control system comprising the estimation device according to any one of claims 1 to 10, the illumination control device according to claim 11, and an illumination device installed in the illumination control area.

13. An estimation method including: the estimation device obtaining measurement results of the brightness of at least two points located in an illumination control area partitioned by a ceiling, a floor, and walls and having an external light incident portion located on the wall; and the estimation device estimating the main direction of external light incident through the external light incident portion from outside the illumination control area based on the measurement results of the brightness of the at least two points.

14. An illumination control method including: the illumination control device controlling an illumination device installed in the illumination control area based on the brightness estimation result obtained by executing the estimation method according to claim 13.

15. An estimation program for causing an estimation device to: obtain measurement results of the brightness of at least two points located in an illumination control area partitioned by a ceiling, a floor, and walls and having an external light incident portion located on the wall; and estimate the main direction of external light incident through the external light incident portion from outside the illumination control area based on the measurement results of the brightness of the at least two points.

16. An illumination control program for causing an illumination control device to control an illumination device installed in the illumination control area based on the brightness estimation result obtained by executing the estimation program according to claim 15.

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