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

Abstract

To provide an estimation device that can estimate the distribution of the brightness in a room with a consideration of the directivity of extraneous light, an illumination control device, an illumination control system, an estimation method, an illumination control method, an estimation program, and an illumination control program.SOLUTION: An estimation device 10 comprises: an acquisition unit 12 that acquires a measurement result of the brightness of at least two points located in an illumination control area 100 that is partitioned by the ceiling 110, the floor 120, and a wall 130, and has an extraneous light incident part 140 located on the wall 130; and an estimation unit 14 that, on the basis of the measurement result of the brightness of the at least two points, estimates a main direction of extraneous light 50 incident from the outside of the illumination control area 100 through the extraneous light incident part 140.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] 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.

Background Art

[0002] A system for calculating indoor daylight illuminance based on a daylight factor corresponding to the sun position is described in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The distribution of indoor brightness due to external light is affected by the directionality of the external light. The directionality of the external light is determined by various factors, not limited to the sun position. An estimation of the brightness distribution considering the directionality of the external light is required.

[0005] An object of the present disclosure is to provide 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 capable of estimating the distribution of indoor brightness considering the directionality of external light.

Means for Solving the Problems

[0006] An estimation device according to an embodiment of the present disclosure includes an acquisition unit and an estimation unit. The acquisition unit acquires measurement results of brightness at at least two points located in a lighting control area partitioned by a ceiling, a floor, and walls and having an external light incident portion located on the wall. The estimation unit estimates a main direction of external light incident through the external light incident portion from outside the lighting control area based on the measurement results of brightness at the at least two points.

[0007] The lighting control device according to an embodiment of the present disclosure controls a lighting device installed in the lighting control area based on the brightness estimation result by the estimation device.

[0008] The lighting control system according to an embodiment of the present disclosure includes the estimation device, the lighting control device, and a lighting device installed in the lighting control area.

[0009] The estimation method according to an embodiment of the present disclosure includes an estimation device acquiring measurement results of brightness at at least two locations located in a lighting control area partitioned by a ceiling, a floor, and walls and having an external light incident portion located on the walls. The estimation method includes the estimation device estimating a main direction of external light incident through the external light incident portion from outside the lighting control area based on the measurement results of the brightness at the at least two locations.

[0010] The lighting control method according to an embodiment of the present disclosure includes a lighting control device controlling a lighting device installed in the lighting control area based on a brightness estimation result obtained by executing the estimation method.

[0011] The estimation program according to an embodiment of the present disclosure causes an estimation device to acquire measurement results of brightness at at least two locations located in a lighting control area partitioned by a ceiling, a floor, and walls and having an external light incident portion located on the walls. The estimation program causes the estimation device to estimate a main direction of external light incident through the external light incident portion from outside the lighting control area based on the measurement results of the brightness at the at least two locations.

[0012] The lighting control program according to an embodiment of the present disclosure causes a lighting control device to control a lighting device installed in the lighting control area based on a brightness estimation result obtained by executing the estimation program.

Advantages of the Invention

[0013] According 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 according to an embodiment of the present disclosure, the distribution of indoor brightness is estimated in consideration of the direction of external light.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2A

Figure 2B

Figure 2C

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0015] (Configuration Example of Lighting Control System 1) As shown in FIG. 1, an illumination control system 1 according to an embodiment includes an illumination control device 10, a brightness measurement device 20, and an illumination device 40. As illustrated in FIGS. 2A, 2B, and 2C, the illumination device 40 and the brightness measurement device 20 are located in an illumination control area 100. The number of the illumination devices 40 is not limited to one and may be two or more. The position of the illumination device 40 may be determined as appropriate. The number of the brightness measurement devices 20 is two or more. The positional relationship of each of the plurality of brightness measurement devices 20 will be described later.

[0016] The illumination control area 100 may include various spaces to be controlled for illumination, such as an office, a conference room, or a classroom. It is assumed that the illumination control area 100 is a space partitioned by a ceiling 110, a floor 120, and a wall 130. The wall 130 has an external light incident portion 140 that transmits external light 50 (see FIGS. 2B and 2C). The external light 50 brightens the illumination control area 100. The external light incident portion 140 may be a window or an opening.

[0017] In the present embodiment, the illumination device 40 and the brightness measurement device 20 are located on the ceiling 110 of the illumination control area 100. The illumination device 40 emits illumination light 60 (see FIG. 2B) from the ceiling 110. The illumination light 60 brightens the illumination control area 100.

[0018] The brightness of each point in the illumination control area 100 corresponds to the intensity of the light incident on each point. The light incident on each point includes direct light and indirect light. The direct light is the light in which the external light 50 or the illumination light 60 directly enters each point. The indirect light is the light that enters after the illumination light 60 or the external light 50 is reflected or scattered at other points. In the present embodiment, it is considered that the intensity of the indirect light is small enough to be ignored compared to the intensity of the direct light. Hereinafter, it is assumed that the brightness of each point in the illumination control area 100 is determined by the intensity of the direct light incident on each point.

[0019] The brightness measurement device 20 measures the brightness of the 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 ambient light 50 incident on the measurement point 80. The stronger the light incident on the measurement point 80, the brighter the measurement point 80 becomes. The brightness of the measurement point 80 may be expressed as the illuminance of the light at the measurement point 80. The brightness of the measurement point 80 may be represented by a value estimated based on an image obtained by photographing the measurement point 80. That is, the value of the brightness of the measurement point 80 may be a value estimated based on an image obtained by photographing the measurement point 80. For example, the brightness measurement device 20 may image the measurement point 80 in the YUV format and measure, as a value representing the brightness of the measurement point 80, a value calculated from the luminance signal Y of the captured image. The brightness of the measurement point 80 is not limited to these examples and may be represented as various other physical quantities. The brightness of the measurement point 80 may be represented by various indices.

[0020] The ambient light 50 is light that enters the illumination control area 100 through the ambient light incident portion 140. The ambient light 50 includes light scattered by the atmosphere, that is, light incident from the blue sky 141 (see FIG. 2A), or light scattered by clouds. The clouds may be classified into white clouds 142 or black clouds 143 (see FIG. 2A), etc., according to the intensity of the light reaching the illumination control area 100. The white cloud 142 is a cloud that appears bright because the light reaching the illumination control area 100 is strong. The black cloud 143 is a cloud that appears dark because the light reaching the illumination control area 100 is weak.

[0021] When the intensity of the light incident on the ambient light incident portion 140 is uniform in all directions, the intensities of the components of the ambient light 50 in each direction are substantially equal. For example, when only the blue sky 141 can be seen when looking outside from the ambient light incident portion 140, the intensity of the light incident on the ambient light incident portion 140 can be uniform in all directions. This is because the blue sky 141 is observed as a result of uniform blue light entering the ambient light incident portion 140.

[0022] Here, when looking out from the external light incident portion 140, as illustrated in FIG. 2A, not only the blue sky 141 but also white clouds 142 or black clouds 143 etc. may be visible. In this case, a distribution occurs in the intensity of the components of the external light 50 in each direction. Specifically, the component of the light incident from the direction where the white clouds 142 are visible is stronger than the component of the light incident from the direction where the blue sky 141 or black clouds 143 are visible.

[0023] In the example of FIG. 2A, when looking out from the illumination control area 100 through the external light incident portion 140, the white clouds 142 are located on the right side with respect to the blue sky 141 or black clouds 143. The light incident on the external light incident portion 140 from the white clouds 142 is stronger than the light incident on the external light incident portion 140 from the blue sky 141 or black clouds 143. Therefore, among the components of the external light 50 in each direction, the component incident in a direction inclined from the right side to the left side with respect to the external light incident portion 140 is strong.

[0024] Also, in the example of FIG. 2A, when looking out from the illumination control area 100 through the external light incident portion 140, the black clouds 143 are located on the left side with respect to the blue sky 141. The light incident on the external light incident portion 140 from the black clouds 143 is weaker than the light incident on the external light incident portion 140 from the blue sky 141. That is, among the components of the external light 50 in each direction, the component incident in a direction inclined from the left side to the right side with respect to the external light incident portion 140 is weak.

[0025] As described above, the external light 50 has directivity. Directivity is the property in which a distribution occurs in the intensity of the components of the external light 50 in each direction. When the intensity of the components of the external light 50 in each direction is uniform, the external light 50 does not have directivity. The directivity of the external light 50 is determined according to the arrangement of the objects such as the blue sky 141, white clouds 142 or black clouds 143 that are the light sources of the external light 50 and are visible from the external light incident portion 140.

[0026] The external light 50 may include direct sunlight. The illumination control device 10 according to the present disclosure estimates the directivity of the external light 50 excluding the direct sunlight among the external light 50.

[0027] When external light 50 excluding direct sunlight enters the illumination control area 100 through the external light incident portion 140, the external light incident portion 140 approximates a surface light source that emits the external light 50. That is, the external light 50 approximates the light emitted from the surface light source. The light emitted from the 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 component of the light traveling in each direction with the highest intensity 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. Also, the component of the light traveling in each direction of the external light 50 with the highest intensity 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.

[0028] The main direction of the surface light source may be a direction that coincides with the normal direction of the light emitting surface of the surface light source. The main direction of the surface light source may be a direction having an angle with respect to the normal direction of the light emitting surface. Assume that the directivity of the external light 50 is represented as the main direction of the surface light source that approximates the external light 50.

[0029] The illumination control device 10 estimates the directivity of the external light 50 based on the measurement results of the brightness measurement device 20 in the illumination control area 100 illustrated in FIGS. 2A, 2B, and 2C. The illumination control device 10 estimates the brightness caused by the external light 50 in the illumination control area 100 based on the estimation result of the directivity of the external light 50. The illumination control device 10 determines the intensity of the illumination light 60 emitted to the illumination device 40, that is, the output of the illumination 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 illumination control area 100.

[0030] Hereinafter, a configuration example of each part of the illumination control system 1 will be described.

[0031] <Illumination control device 10> As shown in FIG. 1, the illumination control device 10 includes an acquisition unit 12, an estimation unit 14, and a control unit 16.

[0032] The acquisition unit 12 acquires the measurement result of the brightness measurement device 20. The acquisition unit 12 may be configured to communicate with the brightness measurement device 20 based on various communication standards such as LAN (Local Area Network) or RS-232C or RS-485. The acquisition unit 12 may be configured to communicate with the brightness measurement device 20 either wired or wirelessly.

[0033] The estimation unit 14 estimates the brightness of the lighting control 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 to the lighting device 40 based on the estimation result of the brightness of the lighting control area 100, and controls the lighting device 40.

[0034] The estimation unit 14 or the control unit 16 may include at least one processor. The processor can execute a program that realizes the functions of the estimation unit 14 or the control unit 16. The processor may be realized as a single integrated circuit or a discrete circuit. The processor may be realized as a plurality of communicably connected integrated circuits or discrete circuits. The processor may be realized based on various other known technologies.

[0035] The lighting control device 10 may further include a storage unit. The storage 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 storage unit may store various information referred to in the operation of the estimation unit 14 or the control unit 16 and a program for realizing various functions of the estimation unit 14 or the control unit 16. The storage unit may function as a working memory of the estimation unit 14 or the control unit 16. The storage 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.

[0036] 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 communicable 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 communicable with the lighting device 40 either wired or wirelessly. Among the control unit 16, the part that generates information for controlling the lighting device 40 and the part that communicates with the lighting device 40 may be configured separately.

[0037] The acquisition unit 12, the estimation unit 14, and the control unit 16 may be integrally configured. The acquisition unit 12 and the estimation unit 14 may be integrally configured. The estimation unit 14 and the control unit 16 may be integrally configured.

[0038] The lighting control device 10 may further include an input device that receives an input such as information or data from a user. The input device may be configured to include, for example, a touch panel or a touch sensor, or a pointing device such as a mouse. The input device may be configured to include physical keys. The input device may be configured to include a voice input device such as a microphone. The lighting control device 10 may be configured to be connectable to an external input device.

[0039] The lighting control device 10 may further include an output device that outputs information, data, etc. to the 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 be configured to include, for example, an LCD (Liquid Crystal Display), an organic EL (Electro-Luminescence) display, an inorganic EL display, or a PDP (Plasma Display Panel), etc. The display device is not limited to these displays and may be configured to include various other types of displays. The display device may be configured to include a light-emitting device such as an LED (Light Emitting Diode) or an LD (Laser Diode). The display device may be configured to 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.

[0040] Among the lighting control device 10, the part that estimates the direction of the external light 50 or the brightness caused by the external light 50 in the lighting control device 10 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 include the acquisition unit 12 of the lighting control device 10. The estimation device may be configured as a separate body from the lighting control device 10.

[0041] <Lighting device 40> The lighting device 40 emits illumination light 60. The lighting device 40 is configured to include various light sources such as, for example, LEDs. The lighting device 40 may be configured as a glareless light. The lighting device 40 is not limited to a glareless light and may be configured in various other manners.

[0042] The number of the lighting devices 40 installed in the lighting control area 100 is not limited to one and may be two or more. When a plurality of lighting devices 40 are installed in the lighting control area 100, the lighting control device 10 may individually control the lighting or extinguishing states of the respective lighting devices 40. Further, the lighting control device 10 may individually set the intensity of the illumination light 60 emitted by each lighting device 40.

[0043] <Brightness measurement device 20> The brightness measurement device 20 measures the brightness of the measurement point 80 (see FIGS. 2B or 2C) located in the lighting control area 100. The brighter the measurement point 80 is, the stronger the light reflected or scattered from the measurement point 80 becomes. The brightness measurement device 20 may measure the intensity of the light reflected or scattered from the measurement point 80 and incident on the brightness measurement device 20 as the brightness of the measurement point 80.

[0044] The brightness measurement device 20 may include an illuminance sensor that measures the illuminance of the measurement point 80. The brightness measurement device 20 may measure the illuminance of the measurement point 80 as the brightness of the measurement point 80. Illuminance is the amount of luminous flux incident on a unit area.

[0045] The brightness measurement device 20 may include an image sensor that images the measurement point 80. The brightness measurement device 20 may measure, as the brightness or illuminance of the measurement point 80, a value calculated from the luminance signal Y of an image obtained by imaging the measurement point 80 in YUV format with the image sensor. The image sensor may include a CCD (Charge Coupled Device Image Sensor), a CMOS (Complementary Metal Oxide Semiconductor) sensor, or the like.

[0046] (Operation example of the lighting control system 1) As described above, the external light 50 has a direction. The direction of the external light 50 affects the distribution of the brightness caused by the external light 50 in the lighting control area 100.

[0047] In the lighting control system 1, the lighting control device 10 estimates the direction of the external light 50 based on the measurement results of the brightness at at least two measurement points 80 located in the lighting control area 100, taking advantage of the fact that the directionality of the external light 50 affects the brightness distribution caused by the external light 50. The lighting control device 10 can estimate the direction of the external light 50 without measuring the overall brightness distribution of the lighting control area 100. As a result, the configuration for measuring brightness can be simplified.

[0048] Based on the estimation result of the direction 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 to 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 control area 100. That is, the lighting control device 10 can estimate the brightness caused by the external light 50 in the entire lighting control area 100 from the measurement results of the brightness at at least two measurement points 80 in the lighting control area 100. As a result, the configuration for measuring brightness can be simplified.

[0049] <Estimation of the direction of the external light 50> Hereinafter, the operation of estimating the direction of the external light 50 will be described. It is assumed that the external light 50 is approximated by light emitted from a surface light source. That is, the external light incident portion 140 is approximated by a surface light source. The lighting control device 10 estimates the main direction of the surface light source as the direction of the external light 50.

[0050] Based on the main direction and the light intensity of the surface light source approximating the external light incident portion 140, the lighting control device 10 can calculate the light intensity incident from each point on the emission surface of the surface light source to an arbitrary point in the lighting control area 100. The value obtained by integrating the light intensities incident from all points on the emission surface of the surface light source to an arbitrary point represents the light intensity incident from the entire surface light source to an arbitrary point. The light intensity incident from the entire surface light source approximating the external light incident portion 140 corresponds to the brightness caused by the external light 50.

[0051] As illustrated in FIG. 3, the light incident on the illumination control area 100 from each point on the light-emitting surface of the surface light source includes a main component represented by a solid line traveling in the main direction from each point on the light-emitting surface of the surface light source, and a component represented by a broken line traveling from each point on the light-emitting surface of the surface light source toward an arbitrary point. In FIG. 3, an arbitrary point for which the illumination control device 10 estimates brightness is represented as an estimation point 70. The illumination control device 10 can calculate the intensity of the light incident on the estimation point 70 from the entire external light incident portion 140 by calculating the sum of the intensities of the components of the light represented by solid lines incident on the estimation point 70 from each point of the external light incident portion 140 approximated to the surface light source. The intensity of the light incident on the estimation point 70 from the entire external light incident portion 140 corresponds to the brightness of the estimation point 70.

[0052] In the present disclosure, it is assumed that the relationship between the main direction of the surface light source and the intensity of the light incident on the estimation point 70 of the illumination control area 100 from each point on the light-emitting surface of the surface light source is represented by a ray volume model. In the ray volume model, the intensity of the light incident on the estimation point 70 from an arbitrary point on the light-emitting surface of the surface light source with respect to the estimation point 70 away from the surface light source is determined according to the positional relationship between an arbitrary point on the light-emitting surface of the surface light source and the estimation point 70. As a method for estimating the brightness caused by external light at a predetermined estimation point, a method using a ray volume model will be described below.

[0053] The distribution of the intensity of the light emitted from an arbitrary point on the light-emitting surface of the surface light source in each direction is approximated by an ellipse having the main direction of the surface light source as the major axis on a plane including the main direction of the surface light source. The degree of flatness of the ellipse may be represented by a form factor. The sharper the directivity of the light emitted from the surface light source, the closer the value of the form factor is set to 0.

[0054] On a plane including the main direction of the surface light source, when the distribution of the intensity of the light emitted from the surface light source in each direction is approximated by an ellipse, the intensity of the component of the light incident on the estimation point 70 from each point of the surface light source changes according to the angle between the traveling direction of the component and the main direction of the surface light source. Specifically, the larger 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.

[0055] When the lighting control device 10 calculates the intensity of the component of the light incident from an arbitrary point on the external light incident portion 140 approximated to a surface light source to the estimation point 70, the intensity of the component to be calculated can 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. The lighting control device 10 may appropriately determine 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 according to the model of the ray volume.

[0056] The intensity of the light incident from an arbitrary point on the emission surface of the surface light source to the estimation point 70 is inversely proportional to the square of the distance that the light travels. That is, the intensity of the component of the light incident from each point of the external light incident portion 140 approximated to the surface light source to the estimation point 70 is inversely proportional to the square of the distance from each point of the external light incident portion 140 to the estimation point 70.

[0057] Here, it is assumed that the angle between the traveling direction of the component of the light incident on the estimation point 70 and the main direction of the surface light source is represented by θ. The distance that the component of the light incident on the estimation point 70 travels from the external light incident portion 140 is calculated as the value obtained by multiplying the distance that the main component of the surface light source travels to the estimation point 70 by 1 / cosθ. Then, the lighting control device 10 can calculate the intensity when the component traveling in the direction represented by the angle θ from the main direction of the surface light source is incident on the estimation point 70 as the value obtained by multiplying the intensity when the main component of the surface light source is incident on the estimation point 70 by the square of cosθ.

[0058] As described above, the lighting control device 10 can calculate the intensity when the component traveling from each point of the external light incident part 140 approximated to a surface light source to the estimation point 70 enters the estimation point 70, considering the direction and distance in which the light travels. In the model of the ray volume, the intensity of the light incident on the estimation point 70 is the total value of the intensities of the light incident on the estimation point 70 from each point on the emission surface of the surface light source. And the intensity of the light incident on the estimation point 70 corresponds to the brightness of the estimation point 70. Therefore, the lighting control device 10 can calculate the brightness caused by the external light 50 at the estimation point 70 by summing up the calculation results of the intensities of the components incident from each point of the external light incident part 140 to the estimation point 70 over the entire external light incident part 140.

[0059] By inversely executing the operation of calculating the brightness of the estimation 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 result of the brightness of the measurement point 80 located in the lighting control area 100.

[0060] The main direction of the external light 50 is specified by the angle with respect to the normal direction of the emission surface of the surface light source approximating the external light incident part 140. In the present disclosure, it is assumed that the emission surface of the surface light source approximating the external light incident part 140 is a plane including the vertical direction. When the emission surface of the surface light source is a plane including the vertical direction, the normal direction of the emission surface of the surface light source is a direction orthogonal to the vertical direction, that is, the horizontal direction. The horizontal direction is a direction included in the horizontal plane orthogonal to the vertical direction.

[0061] 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 the horizontal plane, and is the angle θ H represented as. The vertical angle is the angle with respect to the horizontal plane, and is the angle θ V represented as.

[0062] The lighting control system 1 according to the present disclosure may measure the brightness of measurement points 81 to 88 located as illustrated in FIG. 4 in the lighting control area 100 using a brightness measuring device 20 (see FIGS. 2B or 2C). When there is no need to distinguish, the measurement points 81 to 88 are collectively referred to as a measurement point 80 (see FIGS. 2B and 2C).

[0063] The measurement points 81, 82, and 83 are arranged in a line along the external light incident part 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 the first group.

[0064] The measurement points 84, 85, and 86 are arranged in a line along the external light incident part 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 incident part 140 than the first group and is also referred to as the second group.

[0065] The measurement points 87 and 88 are located farther from the external light incident part 140 than each point of the second group on the floor 120 of the lighting control area 100. The group including the measurement points 87 and 88 is also referred to as the third group.

[0066] Hereinafter, assuming that only the external light 50 is incident on the lighting control area 100, a procedure for estimating the main direction of the external light 50 will be described. That is, a procedure for estimating the main direction of the external light 50 when the lighting device 40 installed in the lighting control area 100 is turned off and not emitting the illumination light 60 will be described.

[0067] <<Estimation of horizontal angle>> When the direction when the main direction of the external light 50 is projected onto the horizontal plane is inclined with respect to the normal direction of the light emitting surface of the surface light source, that is, when 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 be different at each of the plurality of measurement points 80 arranged in the direction along the external light incident part 140.

[0068] As illustrated in FIG. 5, in a plan view of the floor 120 of the lighting control area 100, it is assumed that the measurement points 81, 82, and 83 of the first group are arranged in a line from top to bottom, and the main direction of the external light 50 is inclined downward. In this case, the main component of the external light 50 cannot enter the measurement point 81 located above. On the other hand, the main component of the external light 50 can enter the measurement point 83 located below. In this case, the measurement point 83 may be brighter than the measurement point 81. Also, the difference in brightness between the measurement point 81 and the measurement point 83 can vary according to the horizontal angle of the main component of the external light 50.

[0069] The lighting control device 10 may acquire the measurement results of the brightness of the measurement points 81 and 83 respectively by the acquisition unit 12, and estimate the horizontal angle of the main direction of the external light 50 based on the magnitude of the difference between the measurement result of the brightness of the measurement point 81 and the measurement result of the brightness of the measurement point 83 by the estimation unit 14. The lighting control device 10 may further acquire the measurement result of the brightness of the measurement point 82 by the acquisition unit 12, and estimate the horizontal angle of the main direction of the external light 50 based further on the measurement result of the brightness of the measurement point 82 by the estimation unit 14.

[0070] The first group is not limited to the measurement points 81, 82, and 83, and may include other measurement points 80 arranged in a line along the external light incident portion 140. The acquisition unit 12 may acquire the measurement results of the brightness of at least two of 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 measurement results of the brightness of at least two of the plurality of measurement points 80 in the first group.

[0071] As illustrated in FIG. 5, it is assumed that in a plan view of the floor 120 of the lighting control area 100, in addition to the first group, the measurement points 84, 85, and 86 of the second group are arranged one below the other from top to bottom. In this case, depending on the inclination of the main component of the external light 50, the brightness of the two measurement points 80 arranged in the normal direction of the emission surface of the surface light source approximating the external light incident portion 140 may be different. Specifically, the brightness of the measurement point 81 and the brightness of the measurement point 84 may be different. Also, the brightness of the measurement point 82 and the brightness of the measurement point 85 may be different. Further, the brightness of the measurement point 83 and the brightness of the measurement point 86 may be different.

[0072] The acquisition unit 12 of the lighting control device 10 may acquire the measurement result of the brightness of the measurement point 84, 85, or 86. When the acquisition unit 12 acquires the measurement result of the brightness of the measurement point 81 and the measurement result of the brightness of the measurement point 84, the estimation unit 14 of the lighting control device 10 may estimate the horizontal angle of the main direction of the external light 50 based on the magnitude of the difference between the measurement result of the brightness of the measurement point 81 and the measurement result of the brightness of the measurement point 84.

[0073] 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 measurement result of the brightness of the measurement points 80 in the first group with the measurement result of the brightness of the measurement points 80 in the second group.

[0074] <<Estimation of vertical angle>> The greater the downward inclination of the main direction of the external light 50 with respect to the normal direction of the emission surface of the surface light source, the shorter the distance that the external light 50 reaches into the lighting control 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 a point far from the external light incident portion 140 of the lighting control area 100. That is, the brightness caused by the external light 50 may be different at each of the plurality of measurement points 80 arranged in the direction away from the external light incident portion 140.

[0075] As illustrated in FIG. 6, in a cross-sectional view of the illumination control area 100, it is assumed that the measurement points 82 of the first group and the measurement points 85 of the second group are arranged side by side in a direction away from the external light incident portion 140, and the main direction of the external light 50 is inclined downward. In this case, although the main component of the external light 50 enters the measurement points 82 of the first group that are close to the external light incident portion 140, it cannot enter the measurement points 85 of the second group that are far from the external light incident portion 140. In this case, the measurement points 82 may be brighter than the measurement points 85. Also, the difference in brightness between the measurement points 82 and the measurement points 85 may vary according to the vertical angle of the main component of the external light 50.

[0076] The illumination control device 10 may acquire the measurement results of the brightness of each of the measurement points 82 and 85 by 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 measurement result of the brightness of the measurement point 82 and the measurement result of the brightness of the measurement point 85 by the estimation unit 14.

[0077] The measurement point 82 is also referred to as the first point. The measurement point 85 is also referred to as the second point. The second point, that is, the measurement point 85, is located farther from the external light incident portion 140 than the first point, that is, 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 measurement results of the brightness of each of the first point and the second point.

[0078] The acquisition unit 12 may acquire measurement results of the brightness at other locations such as measurement location 81 or 83, not limited to measurement location 82, among the first group. When the acquisition unit 12 acquires the measurement result of the brightness at measurement location 81 of the first group, it may acquire the measurement result of the brightness at measurement location 84 that is located in the normal direction of the external light incident unit 140 with respect to measurement location 81 of the first group among the second group. That is, the acquisition unit 12 may select locations arranged in the normal direction of the external light incident unit 140 from each of the first group and the second group, and acquire the measurement results of the brightness at the selected locations. The estimation unit 14 may estimate the vertical angle of the main direction of the external light 50 based on the measurement results of the brightness at at least one location in the first group and the measurement results of the brightness at at least one location in the second group. Among the locations where the estimation unit 14 measures the brightness to estimate the vertical angle of the main direction of the external light 50, the number of locations in the second group may be less than the number of locations in the first group.

[0079] The acquisition unit 12 may also acquire the measurement result of the brightness at measurement location 80 of the third group, which is further away 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 measurement results of the brightness at measurement location 80 of the first group and the second group, based on the measurement result of the brightness at measurement location 80 of the third group. When the acquisition unit 12 acquires the measurement result of the brightness at measurement location 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 measurement result of the brightness at measurement location 80 of the first group and the measurement result of the brightness of the third group. The estimation unit 14 may also estimate the vertical angle of the main direction of the external light 50 based on the measurement result of the brightness at measurement location 80 of the second group and the measurement result of the brightness of the third group. Among the locations where the estimation unit 14 measures the brightness to estimate the vertical angle of the main direction of the external light 50, the number of locations in the third group may be less than the number of locations in the first group.

[0080] The points of each of the first group, the second group, and the third group selected by the acquisition unit 12 do not have to be arranged in the normal direction of the external light incident unit 140. The acquisition unit 12 may acquire measurement results of the brightness of at least two points with different distances from the external light incident unit 140 along the direction when the main direction of the external light 50 is projected onto the horizontal plane in a plan view of the illumination control area 100.

[0081] <<Estimation Considering the Influence of the Illumination Light 60>> In the procedure described above, the brightness of each point in the illumination control area 100 is calculated as the brightness caused only by the external light 50. When the lighting device 40 installed in the illumination control area 100 emits the illumination light 60, the brightness of each point in the illumination control area 100 is the combined brightness of the brightness caused by the external light 50 and the brightness caused by the illumination light 60.

[0082] The estimation unit 14 of the illumination control device 10 calculates a value obtained by subtracting the brightness caused by the illumination light 60 from the measurement result of the brightness of each point in the illumination control area 100 acquired by the acquisition unit 12. That is, the estimation unit 14 may remove the component caused by the illumination light 60 from the brightness of each point in the illumination control area 100. The estimation unit 14 may regard the brightness from which the component caused by the illumination light 60 is removed as the brightness caused by the external light 50 and estimate the main direction of the external light 50.

[0083] The estimation unit 14 may calculate the brightness of each point caused by the illumination light 60 based on the installation position of the lighting device 40 and the output of the lighting device 40. The output of the lighting device 40 may be represented as the intensity of the illumination light 60 emitted from the lighting device 40. The output of the lighting device 40 may be represented as the power input to the lighting device 40.

[0084] Specifically, the estimation unit 14 may calculate the intensity of the illumination light 60 emitted from the illumination device 40 in each direction based on the output of the illumination device 40. When one illumination device 40 is installed in the illumination control area 100, the estimation unit 14 may calculate the intensity of the illumination light 60 incident from one illumination device 40 on each point in the illumination control area 100 as the brightness caused by the illumination light 60 at each point. That is, the estimation unit 14 can calculate the distribution of the brightness caused by the illumination light 60 emitted from one illumination device 40.

[0085] When a plurality of illumination devices 40 are installed in the illumination control area 100, the estimation unit 14 may calculate the intensity of the component of the illumination light 60 incident from each illumination device 40 on an arbitrary point in the illumination control area 100 and sum them up, thereby calculating the total intensity of the illumination light 60 incident from the plurality of illumination devices 40 on the arbitrary point. The estimation unit 14 may calculate the total intensity of the illumination light 60 incident on an 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 in the illumination control area 100 by calculating the total intensity of the illumination light 60 incident on each point in the illumination control area 100. That is, the estimation unit 14 can calculate the distribution of the brightness caused by the illumination light 60 emitted from the plurality of illumination devices 40.

[0086] The estimation unit 14 may calculate the intensity of the illumination light 60 by assuming that the intensity of the component of the illumination light 60 emitted from the illumination device 40 is uniform in each direction. That is, the estimation unit 14 may assume that the illumination light 60 emitted from the illumination device 40 has no directivity. The estimation unit 14 may also calculate the brightness caused by the illumination light 60 in consideration of the directivity of the illumination light 60 emitted from the illumination device 40.

[0087] <<Estimation of the directivity of the external light 50 (parentheses)>> As described above, the estimation unit 14 can estimate the main direction of the external light 50. 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 of the main direction of the external light 50. The estimation unit 14 may estimate only the vertical angle of the main direction of the external light 50.

[0088] <Estimation of brightness due to the external light 50> Based on the estimation result of the main direction of the external light 50, the estimation unit 14 of the lighting control device 10 can estimate the brightness due to the external light 50 at any point in the lighting control area 100. The estimation unit 14 may estimate the distribution of the brightness due to the external light 50 in the lighting control area 100 by estimating the brightness due to the external light 50 at a plurality of points in the lighting control area 100.

[0089] 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 of the external light incident unit 140 based on the main direction of the external light 50. The estimation unit 14 identifies the component of the light incident from each point of the external light incident unit 140 to an arbitrary point in the lighting control area 100, and calculates the intensity of the light incident on an arbitrary point in the lighting control area 100 by summing the intensities of the identified light components.

[0090] The estimation unit 14 may output the calculation result of the intensity of the light incident on an arbitrary point in the lighting control area 100 as an estimation result of the brightness at an arbitrary point in the lighting control area 100. The estimation unit 14 may set a conversion coefficient that specifies the relationship between the light intensity and the brightness, and output the value obtained by multiplying the value of the calculation result of the intensity of the light incident on an arbitrary point by the conversion coefficient as an estimated value of the brightness at the arbitrary point. The estimation unit 14 may also output the value of the calculation result of the intensity of the light incident on an arbitrary point as it is as an estimated value of the brightness at the arbitrary point.

[0091] 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 portion 140 based on the estimation result of the horizontal angle, and calculate the brightness distribution in the normal direction of the external light incident portion 140 based on the estimation result of the vertical angle.

[0092] 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 the direction along the emission surface of the surface light source approximated by the external light incident portion 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 portion 140 using a value set in advance as the vertical angle. The estimation unit 14 may use, for example, the altitude of the sun or a value set according to the environment outside the external light incident portion 140 as the vertical angle.

[0093] 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 portion 140 based on the estimation result of the vertical angle. The estimation unit 14 may calculate the brightness distribution in the direction along the emission surface of the surface light source approximated by the external light incident portion 140 using a value set in advance as the horizontal angle. The estimation unit 14 may use, for example, the azimuth of the sun or a value set according to the environment outside the external light incident portion 140 as the horizontal angle.

[0094] <Control of the 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 or 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.

[0095] The control unit 16 may set the control target of the brightness at each point in the lighting control area 100, and determine the output of the lighting device 40 so as to compensate for the difference between the control target of the brightness and the estimated result of the brightness caused by the external light 50 with the brightness caused by the lighting light 60.

[0096] The control unit 16 may set the control target of the brightness so as to make the brightness distribution in the lighting control area 100 uniform. The control unit 16 may also set the control target of the brightness so as to brighten only a specific area in the lighting control area 100.

[0097] The control unit 16 may set the area to be brightened as the area where a human exists in the lighting control area 100. The control unit 16 may acquire the area where a human exists in the lighting control area 100 based on information such as a human presence sensor or a camera installed in the lighting control area 100. The lighting control system 1 may include a device capable of detecting the position of a human in the lighting control area 100.

[0098] The control unit 16 determines the output of the lighting device 40 so as to control the brightness caused by the lighting light 60 at each point in the lighting control area 100. The output of the lighting device 40 may be represented as the intensity of the lighting light 60 emitted from the lighting device 40. The output of the lighting device 40 may be represented as the power input to the lighting device 40.

[0099] Specifically, the control unit 16 may calculate the intensity of the lighting light 60 that needs to be incident on each point so that the brightness caused by the lighting light 60 at each point in the lighting control area 100 matches the control target.

[0100] On the other hand, based on the distribution of the components of the lighting light 60 emitted from each of the plurality of lighting devices 40 installed in the lighting control area 100 toward each point in the lighting control area 100, that is, based on the directivity of the lighting light 60, the control unit 16 may calculate the intensity of the lighting light 60 incident from each lighting device 40 on each point in the lighting control area 100 using a mathematical formula including the output of each lighting device 40 as a parameter.

[0101] 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 illumination device 40 for each point in the illumination control area 100. The control unit 16 generates an evaluation function that outputs the difference between the value calculated by the mathematical formula generated for each point in the illumination control area 100 and the intensity of the illumination light 60 that needs to be incident on each point in the illumination control area 100, and may determine the output of each illumination device 40 by solving a linear programming problem that minimizes the value of the evaluation function. In order to achieve power saving of the illumination device 40, the evaluation function may include a term for the sum of the outputs of each illumination device 40.

[0102] The control unit 16 is not limited to the method based on the above-described evaluation function, and may determine the output of the illumination device 40 using various other methods.

[0103] <An example of the information flow in the illumination control system 1> The illumination control system 1 can control the brightness of the illumination control area 100 through the mutual cooperation of the illumination control device 10, the brightness measurement device 20, and the illumination device 40. Hereinafter, with reference to FIG. 7, the information flow among the illumination control device 10, the brightness measurement device 20, and the illumination device 40 in the illumination control system 1 will be described.

[0104] The brightness measurement device 20 outputs the measured value of the brightness at the first group of measurement points 80 to the illumination control device 10. The brightness measurement device 20 outputs the measured value of the brightness at the second group of measurement points 80 to the illumination control device 10. The measurement result of the brightness by the brightness measurement device 20 is the brightness obtained by combining the brightness caused by the external light 50 and the brightness caused by the illumination light 60.

[0105] The illumination device 40 outputs the brightness caused by the illumination light 60 emitted by the illumination device 40 to the illumination control device 10. The illumination device 40 may output the set value of the intensity of the illumination light 60 emitted by the illumination device 40 to the illumination control device 10.

[0106] The lighting control device 10 calculates the brightness caused by the external light 50 at the measurement points 80 in the first group by subtracting the brightness caused by the lighting light 60 from the measured value of the brightness at the measurement points 80 in the first group. The lighting control device 10 calculates the brightness caused by the external light 50 at the measurement points 80 in the second group by subtracting the brightness caused by the lighting light 60 from the measured value of the brightness at the measurement points 80 in the second group. When the lighting control device 10 acquires the set value of the intensity of the lighting light 60 from the lighting device 40, based on the set value of the intensity of the lighting light 60 and the directivity characteristics of the lighting light 60 emitted by the lighting device 40, the lighting control device 10 calculates the brightness caused by the lighting light 60 at each measurement point 80.

[0107] Based on the brightness caused by the external light 50 at the measurement points 80 in the first group and the brightness caused by the external light 50 at the measurement points 80 in the second group, the lighting control device 10 may estimate the horizontal angle of the main direction of the external light 50. Based only on the brightness caused by the external light 50 at the measurement points 80 in the first group, the lighting control device 10 may estimate the horizontal angle of the main direction of the external light 50.

[0108] Based on the brightness caused by the external light 50 at the measurement points 80 in the first group and the brightness caused by the external light 50 at the measurement points 80 in the second group, the lighting control device 10 may estimate the vertical angle of the main direction of the external light 50. Based further on the estimation result of the horizontal angle of the main direction of the external light 50, the lighting control device 10 may estimate the vertical angle of the main direction of the external light 50.

[0109] Based on at least one of the horizontal angle or the vertical angle of the main direction of the external light 50, the lighting control device 10 estimates the distribution of the brightness caused by the external light 50 at points other than the measurement points 80 in the lighting control area 100. Based on the distribution of the brightness caused by the external light 50 in the lighting control area 100, the lighting control device 10 determines the output of the lighting device 40 so as to be able to control the brightness of each point in the lighting control area 100, and outputs it to the lighting device 40. The lighting device 40 emits the lighting light 60 based on the output determined by the lighting control device 10.

[0110] As described above, in the lighting control system 1, information flows among the lighting control device 10, the brightness measurement device 20, and the lighting device 40, whereby the brightness of the lighting control area 100 is controlled. The lighting control system 1 can control the lighting device 40 so as to maintain the brightness of the lighting control area 100 even when the intensity of the external light 50 changes by repeatedly estimating the brightness caused by the external light 50.

[0111] The brightness measurement device 20 may output the measurement value of the brightness at the measurement point 80 located in the lighting control area 100 to the lighting control device 10. The lighting control device 10 may calculate the brightness caused by the external light 50 at the measurement point 80 of the third group from the measurement value of the brightness at the measurement point 80 of the third group. The lighting control device 10 may further estimate the vertical angle of the main direction of the external light 50 based on the brightness caused by the external light 50 at the measurement point 80 of the third group.

[0112] <Example of the procedure of the estimation method> The estimation unit 14 of the lighting control device 10 may execute an estimation method including the procedure of the flowchart illustrated in FIG. 8. The estimation method may be realized as an estimation program that causes the processor constituting the estimation unit 14 to execute. The estimation program may be stored in a non-transitory computer-readable medium.

[0113] The estimation unit 14 acquires the measurement result of the brightness at the measurement point 80 located in the lighting control area 100 from the brightness measurement device 20 (step S1).

[0114] The estimation unit 14 removes the component caused by illumination from the measurement result of the brightness at the measurement point 80 (step S2). Specifically, the estimation unit 14 acquires information on the output of the lighting device 40, calculates the brightness caused by the illumination light 60, and subtracts the brightness caused by the illumination light 60 from the measurement result of the brightness at the measurement point 80, thereby removing the component caused by illumination. The value calculated by removing the component caused by illumination from the measurement result of the brightness at the measurement point 80 corresponds to the brightness caused by the ambient light 50 at the measurement point 80.

[0115] The estimation unit 14 estimates the main direction of the ambient light 50 based on the brightness caused by the ambient 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 ambient light 50. The estimation unit 14 may estimate only the horizontal angle of the main direction of the ambient light 50, or may estimate only the vertical angle.

[0116] The estimation unit 14 estimates the brightness caused by the ambient 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 result of the brightness at each point in the lighting control area 100 to the control unit 16. After executing 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 execute the procedures from step S1 to S4. The estimation unit 14 may output the estimation result of the main direction of the ambient light 50 after step S3.

[0117] <Example procedure of lighting control method> The control unit 16 of the 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 that causes a processor constituting the control unit 16 to execute. The lighting control program may be stored in a non-transitory computer-readable medium.

[0118] The control unit 16 acquires the estimation result of the brightness caused by the ambient light 50 at each point in the lighting control area 100 from the estimation unit 14 (step S11).

[0119] Based on the estimation results of the brightness caused by the external light 50 at each point in the lighting control area 100, the control unit 16 determines the output of the lighting device 40 so as to control the brightness at each point in the lighting control area 100 (step S12). The output of the lighting device 40 may be specified as the intensity of the illumination light 60 emitted by the lighting device 40. The output of the lighting device 40 may also be specified as the power input to the lighting device 40.

[0120] The control unit 16 controls the lighting device 40 based on the output of the lighting device 40 determined in the procedure of step S12 (step S13). The lighting device 40 emits the illumination light 60 with the output determined in the procedure of step S12. After executing the procedure of step S13, the control unit 16 ends the execution of the procedure of the flowchart in FIG. 9.

[0121] <Summary> As described above, the lighting control system 1 measures the brightness at at least two measurement points 80 in the lighting control area 100 with 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 only from the measurement results of the brightness at the two measurement points 80. That is, by simply obtaining the measurement results of the brightness at the two measurement points 80, the distribution of the brightness in the lighting control area 100, that is, the indoor brightness distribution, is estimated in consideration of the directivity of the external light 50. As a result, the number of points for measuring the brightness is minimized.

[0122] In addition, the lighting control system 1 can determine the output of the lighting device 40 based on the estimation results of the brightness distribution at each point in the lighting control area 100. That is, the brightness distribution of the entire lighting control area 100 is controlled only from the measurement results of the brightness at the two measurement points 80. As a result, the configuration for measuring the brightness, which is used to control the brightness distribution in the lighting control area 100, is simplified.

[0123] The drawings for explaining the embodiments according to the present disclosure are schematic. The dimensional ratios on the drawings do not necessarily match the actual ones.

[0124] Those skilled in the art can make various modifications and alterations based on the present disclosure. Therefore, these modifications and alterations are included in the scope of the present disclosure. For example, in each embodiment, each functional unit, each means, or each step, etc. can be added to other embodiments so as not to be logically contradictory, or can be replaced with each functional unit, each means, or each step, etc. of other embodiments. Also, in each embodiment, a plurality of each functional unit, each means, or each step, etc. can be combined into one or divided. Further, each embodiment of the present disclosure described above is not limited to being faithfully implemented in each described embodiment, and can also be implemented by appropriately combining each feature or omitting a part thereof.

[0125] In the present disclosure, descriptions such as "first" and "second" are identifiers for distinguishing the relevant components. The components distinguished by the descriptions such as "first" and "second" in the present disclosure can have their numbers in the component exchanged. For example, the first group can exchange the "first" and "second" which are identifiers with the second group. The exchange of identifiers is performed simultaneously. The components are still distinguishable after the exchange of identifiers. The identifiers can be deleted. The components after deleting the identifiers are distinguished by symbols. Based only on the descriptions of identifiers such as "first" and "second" in the present disclosure, the order of the components should not be interpreted, nor should it be used as the basis for the existence of an identifier with a smaller number.

[0126] In one embodiment, (1) the estimation device includes an acquisition unit that acquires measurement results of illuminance at at least two locations 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 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 illuminance at the at least two locations.

[0127] (2) In the estimation device according to (1) above, the at least two points may include a first group including a plurality of points arranged along the external light incident portion on the floor. The estimation unit may estimate a horizontal angle of the main direction of the external light based on the measurement results of the brightness of each point in the first group.

[0128] (3) In the estimation device according to (2) above, the at least two points may include a second group including at least one point located farther from the external light incident portion than each point in the first group. The estimation unit may further estimate a horizontal angle of the main direction of the external light based on the measurement results of the brightness of each point in the second group.

[0129] (4) In the estimation device according to (3) above, the estimation unit may estimate a vertical angle of the main direction of the external light based on the measurement result of the brightness of at least one point in the first group and the measurement result of the brightness of at least one point in the second group.

[0130] (5) In the estimation device according to (4) above, the number of points in the second group may be less than the number of points in the first group.

[0131] (6) In the estimation device according to (3) above, the at least two points may include a third group including at least one point located farther from the external light incident portion than each point in the second group. The estimation unit may estimate a vertical angle of the main direction of the external light based on the measurement result of the brightness of at least one point in the first group and the measurement result of the brightness of at least one point in the third group.

[0132] (7) In the estimation device according to (6) above, the number of points in the third group may be less than the number of points in the first group.

[0133] (8) In the estimation device according to (1) above, the at least two points may include a first point and a second point located farther from the external light incident portion than the first point. The estimation unit may estimate a vertical angle of the main direction of the external light based on the measurement results of the brightness of each of the first point and the second point.

[0134] (9) In the estimation device according to any one of (1) to (8) above, the estimation unit may estimate 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.

[0135] (10) In the estimation device according to (9) above, the estimation unit may estimate the brightness distribution in the illumination control area.

[0136] In one embodiment, (11) the illumination control device controls the illumination device installed in the illumination control area based on the brightness estimation result by the estimation device according to (9) or (10) above.

[0137] In one embodiment, (12) the illumination control system includes the estimation device according to any one of (1) to (10) above, the illumination control device according to claim 11, and the illumination device installed in the illumination control area.

[0138] In one embodiment, (13) the estimation method includes the estimation device acquiring 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 the 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.

[0139] In one embodiment, the (14) lighting control method includes controlling a lighting device installed in the lighting control area by a lighting control device based on an estimated brightness result obtained by executing the estimation method described in the above (13).

[0140] In one embodiment, the (15) estimation program causes an estimation device to acquire measurement results of brightness at at least two points located in a lighting control area partitioned by a ceiling, a floor, and walls and having an external light incident portion located on the walls, and to estimate a main direction of external light incident through the external light incident portion from outside the lighting control area based on the measurement results of brightness at the at least two points.

[0141] In one embodiment, the (16) lighting control program causes a lighting control device to control a lighting device installed in the lighting control area based on an estimated brightness result obtained by executing the estimation program described in the above (15).

Explanation of Reference Numerals

[0142] 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 Lighting light 80 - 88 Measurement points 100 Lighting control area (110: Ceiling, 120: Floor, 130: Walls, 140: External light incident portion (141: Blue sky, 142: White cloud, 143: Black cloud)

Claims

1. 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 wall; 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 An estimation device comprising:

2. The at least two points include a first group including a plurality of points arranged along the external light incident portion above the floor, 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. The estimation device according to claim 1.

3. 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, 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. The estimation device according to claim 2.

4. 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. The estimation device according to claim 3.

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

6. 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, 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. The estimation device according to claim 3.

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

8. 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, The estimation unit estimates a vertical angle of the main direction of the external light based on the measurement results of brightness at each of the first point and the second point. The estimation device according to claim 1.

9. The estimation device according to claim 1, 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. The estimation device obtains measurement results of the brightness of at least two points located in an illumination control area partitioned by a ceiling, a floor, and a wall and having an external light incident portion located on the wall. The estimation device estimates 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. An estimation method comprising:

14. An illumination control method comprising controlling, by an illumination control device, 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. Obtaining measurement results of the brightness of at least two points located in an illumination control area partitioned by a ceiling, a floor, and a wall and having an external light incident portion located on the wall. 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. An estimation program for causing an estimation device to execute:

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.

Images