Lighting control system

Abstract

To improve a visual comfort.SOLUTION: External light illuminance sensors 11a and 11b detect an illuminance of a surface on which an external light incident from a window is incident. A wall surface illuminance sensor 12 detects the illuminance of a wall surface of an indoor space having the window. A window surface luminance calculation part 31 calculates the window surface luminance of the window based on the illuminance detected by the external light illuminance sensors 11a and 11b. A wall surface luminance calculation part 32 calculates the wall surface luminance of the wall surface based on the illuminance detected by the wall surface illuminance sensor 12. A luminance ratio calculation part 33 calculates a luminance ratio by calculating a quotient obtained by dividing the window surface luminance calculated by the window surface luminance calculation part 31 by the wall surface luminance calculated by the wall surface luminance calculation part 32. A control part 37 controls an illumination device installed in the indoor space based on the luminance ratio calculated by the luminance ratio calculation part 33.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a lighting control system for controlling a lighting device. [Background technology]

[0002] Patent Document 1 discloses a lighting control system that detects the illuminance of natural light incident on an area illuminated by a lighting load, and controls the lighting load based on the detected illuminance. Non-Patent Document 1 proposes a method for controlling the luminance contrast between a window and the wall surrounding it. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-029034 [Non-patent literature]

[0004] [Non-Patent Document 1] Mika Kato et al., "Study on the preferred luminance contrast between window surfaces and their surroundings when using daylight (Part 1): Study on lower windows including blinds," Journal of Environmental Engineering, Architectural Institute of Japan, Vol. 86, No. 790, pp. 883-891, December 2021. Summary of the Invention [Problem to be solved by the invention]

[0005] The lighting control system of Patent Document 1 aims to save energy by turning off part or all of the lighting loads when the illuminance of natural light incident on the lighting area is high. However, when strong external light is coming in through a window, if the lighting is dimmed, the areas not exposed to the external light will become dark, increasing the brightness ratio with the window and resulting in a deviation from the desired brightness ratio. The present invention aims to solve such problems, for example. [Means for solving the problem]

[0006] The lighting control system includes an external light illuminance sensor that detects the illuminance of a surface hit by external light entering through a window; a wall surface illuminance sensor that detects the illuminance of a wall surface in an indoor space where the window is located; a window surface luminance calculation unit that calculates the window surface luminance of the window based on the illuminance detected by the external light illuminance sensor; a wall surface luminance calculation unit that calculates the wall surface luminance of the wall surface based on the illuminance detected by the wall surface illuminance sensor; a luminance ratio calculation unit that calculates a luminance ratio by dividing the window surface luminance calculated by the window surface luminance calculation unit by the wall surface luminance calculated by the wall surface luminance calculation unit; and a control unit that controls lighting devices installed in the indoor space based on the luminance ratio calculated by the luminance ratio calculation unit. [Effects of the Invention]

[0007] The lighting device is controlled taking into consideration not only the indoor illuminance condition but also the luminance ratio condition, so it is possible to prevent the indoor space from feeling dark even when the indoor illuminance condition is met, thereby improving visual comfort. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a side view showing an example of a lighting control system. [Figure 2] FIG. 2 is a block diagram showing an example of a control device. [Figure 3] FIG. 4 is a flowchart showing an example of a lighting control process. DETAILED DESCRIPTION OF THE INVENTION

[0009] Referring to FIG. 1, a lighting control system 10 will be described. The lighting control system 10 controls lighting devices 14a and 14b installed in an indoor space such as a room having a window 81 through which external light 91 enters. The lighting control system 10 includes, for example, ambient light illuminance sensors 11a and 11b, a wall surface illuminance sensor 12, a control device 13, and lighting devices 14a and 14b.

[0010] The lighting devices 14a and 14b are installed, for example, on a ceiling 83 of the indoor space 80 and illuminate the indoor space 80.

[0011] The external light illuminance sensors 11a and 11b are installed on the ceiling 83, for example. The external light illuminance sensor 11a is disposed, for example, near the lighting device 14a, and detects the illuminance of reflected light 92a that is reflected by a light receiving surface 82 on which external light 91 that has entered through a window 81 is incident. The external light illuminance sensor 11b is disposed, for example, near the lighting device 14b, and detects the illuminance of reflected light 92b that is reflected by a light receiving surface 82 on which external light 91 that has entered through a window 81 is incident. The ambient light illuminance sensors 11a and 11b output signals representing the detected illuminance. The external light illuminance sensors 11a and 11b are arranged so as not to be affected by the light emitted by the lighting devices 14a and 14b.

[0012] The wall illuminance sensor 12 is installed, for example, on a wall 84 of the indoor space 80, and detects the illuminance of light incident from all directions. The wall surface illuminance sensor 12 outputs a signal representing the detected illuminance.

[0013] The control device 13 controls the lighting device 14a based on the illuminance detected by the external light illuminance sensor 11a and the wall surface illuminance sensor 12, and controls the lighting device 14b based on the illuminance detected by the external light illuminance sensor 11b and the wall surface illuminance sensor 12, for example. The control device 13 receives, for example, signals output by the external light illuminance sensors 11a and 11b and the wall surface illuminance sensor 12, and outputs control signals for controlling the lighting devices 14a and 14b. These signals may be transmitted by wire or wirelessly, or via a network such as a local area network or the Internet, or via a communication line such as a public communication line.

[0014] The control device 13 will be described in detail with reference to FIG. The control device 13 is a computer such as a server device, and executes a stored computer program to realize the functional blocks described below. The server device may be one or more physically independent devices, or may be virtually constructed on the cloud. The control device 13 is not limited to a computer, and may be realized by hardware such as a logic circuit. Furthermore, functional blocks realized by software and functional blocks realized by hardware may be mixed. The control device 13 includes, for example, a window surface luminance calculation unit 31, a wall surface luminance calculation unit 32, a luminance ratio calculation unit 33, an external light illuminance calculation unit 34, an illumination illuminance calculation unit 35, an indoor illuminance calculation unit 36, and a control unit 37.

[0015] The window surface luminance calculation unit 31 calculates the window surface luminance of the window 81 based on the illuminance detected by the external light illuminance sensors 11a and 11b. The window surface luminance is the average luminance when the window 81 is viewed from a predetermined point in the indoor space 80. Since the luminance varies depending on the positional relationship between the observation point and the light-emitting surface, for example, for each of the external light illuminance sensors 11a and 11b, the window surface luminance calculation unit 31 sets as an observation point a predetermined position within an illumination area illuminated by the lighting device 14a or 14b located near the position where the external light illuminance sensor 11a or 11b is installed, and calculates the window surface luminance when the window 81 is viewed from the observation point. Specifically, for example, the intensity of external light 91 striking the light receiving surface 82 is estimated based on the illuminance detected by the external light illuminance sensor 11a or 11b, the luminous flux of external light 91 reaching the observation point through the window 81 is estimated based on the estimated intensity of external light 91, and the window surface luminance is estimated from the estimated luminous flux based on the positional relationship between the window 81 and the observation point. Alternatively, for example, the relationship between the illuminance detected by the external light illuminance sensors 11a and 11b and the window surface luminance as seen from an observation point may be measured in advance, and the window surface luminance may be estimated based on the measured relationship. For example, a luminance meter may be installed at the observation point to measure the window surface luminance, and at the same time, the external light illuminance sensors 11a and 11b may detect the illuminance, thereby actually measuring the relationship between the illuminance and the window surface luminance. Alternatively, for example, the relationship between illuminance and window surface luminance may be estimated in advance by computer simulation or the like, and the window surface luminance may be estimated based on the estimated relationship.

[0016] The wall surface luminance calculation unit 32 calculates the wall surface luminance of the wall 84 based on the illuminance detected by the wall surface illuminance sensor 12. The wall surface luminance calculation unit 32 calculates the wall surface luminance for each observation point at which the window surface luminance calculation unit 31 calculated the window surface luminance, for example. Specifically, for example, the intensity of light falling on the wall 84 is estimated based on the illuminance detected by the wall illuminance sensor 12, the intensity of light reflected by the wall 84 is estimated from the estimated intensity of light falling on the wall 84 based on the reflectance of the wall 84, the luminous flux of light reaching the observation point from the wall 84 is estimated based on the estimated intensity of light reflected by the wall 84, and the wall luminance is estimated from the estimated luminous flux based on the positional relationship between the wall 84 and the observation point. Alternatively, for example, assuming that the wall surface is an equal-diffuse reflecting surface, the wall surface luminance calculation unit 32 calculates the product by dividing the reflectance of the wall 84 by pi (π) and multiplying the quotient by the illuminance detected by the wall surface illuminance sensor 12, and determines the calculated product as the wall surface luminance of the wall 84 at the point where the wall surface illuminance sensor 12 is installed.

[0017] The luminance ratio calculation unit 33 calculates a luminance ratio based on the window surface luminance calculated by the window surface luminance calculation unit 31 and the wall surface luminance calculated by the wall surface luminance calculation unit 32. The luminance ratio is the ratio of the window surface luminance to the wall surface luminance, and the luminance ratio increases as the window surface luminance increases, and decreases as the wall surface luminance increases. The window surface luminance calculation unit 31 calculates the luminance ratio for each observation point where the window surface luminance calculation unit 31 has calculated the window surface luminance and the wall surface luminance calculation unit 32 has calculated the wall surface luminance, for example. Specifically, for example, the luminance ratio at each observation point is calculated by dividing the window surface luminance by the wall surface luminance.

[0018] The external light illuminance calculation unit 34 calculates the illuminance due to external light 91 based on the illuminance detected by the external light illuminance sensors 11a and 11b. The light present in the indoor space 80 includes light based on external light 91, such as external light 91 entering through the window 81 and light reflected when the external light 91 hits something and is reflected, and light based on the lighting devices 14a and 14b, such as light emitted by the lighting devices 14a and 14b and light reflected when that light hits something and is reflected. The illuminance due to external light 91 refers to the portion of the illuminance at a given point in the indoor space 80 that is due to light based on external light 91. Since illuminance varies depending on the location, the external light illuminance calculation unit 34 calculates the external light illuminance at each of the lighting devices 14a and 14b, for example, by setting a predetermined position within the lighting area of ​​each of the lighting devices 14a and 14b as a target location. Specifically, for example, similar to the window surface luminance calculation unit 31, the intensity of the external light 91 striking the light receiving surface 82 is estimated based on the illuminance detected by the external light illuminance sensor 11a or 11b, the luminous flux of light based on the external light 91 reaching a specified point is estimated based on the estimated intensity of the external light 91, and the external light illuminance is estimated from the estimated luminous flux. Alternatively, for example, the relationship between the illuminance detected by the external light illuminance sensors 11a and 11b and the external light illuminance at a target point may be measured in advance, and the external light illuminance may be estimated based on the measured relationship. For example, an illuminance sensor may be installed at the target point, and the external light illuminance may be measured by detecting the illuminance at the target point with the lighting devices 14a and 14b turned off. At the same time, the external light illuminance sensors 11a and 11b may detect the illuminance, thereby measuring the relationship between the illuminance detected by the external light illuminance sensors 11a and 11b and the external light illuminance. Alternatively, for example, the relationship between the illuminance detected by the ambient light illuminance sensors 11a and 11b and the ambient light illuminance may be estimated in advance by computer simulation or the like, and the ambient light illuminance may be estimated based on the estimated relationship.

[0019] The target point for which the external light illuminance calculation unit 34 calculates the external light illuminance is usually different from the observation point for which the window surface luminance calculation unit 31 and the wall surface luminance calculation unit 32 calculate the luminance. This is because the observation point for which the luminance is calculated is set, for example, at the position of the observer's viewpoint, whereas the target point for which the illuminance is calculated is set, for example, at the position of the surface of a work desk.

[0020] The illumination illuminance calculation unit 35 calculates the illumination illuminance based on the lighting states of the lighting devices 14a and 14b. The illumination illuminance refers to the illuminance at a predetermined point in the indoor space 80 that is due to light from the lighting devices 14a and 14b. The lighting states of the lighting devices 14a and 14b refer to, for example, whether they are on or off, and if they are on, what dimming rate they are at. Because the lighting devices 14a and 14b are controlled by the control unit 37 of the control device 13, the illumination illuminance calculation unit 35 obtains the lighting states of the lighting devices 14a and 14b from the control unit 37. The illumination illuminance calculation unit 35 calculates the illumination illuminance for each target point for which the ambient light illuminance calculation unit 34 calculates the ambient light illuminance, for example. Specifically, for example, the illumination illuminance at the target point is calculated by multiplying the dimming rate of the lighting devices 14a and 14b by a design value that is designed as the illuminance at the target point when the lighting devices 14a and 14b are turned on at 100%. Note that, in consideration of the aging deterioration of the lighting devices 14a and 14b, a dimming rate due to aging deterioration may be calculated based on the cumulative lighting time of the lighting devices 14a and 14b, and the calculated dimming rate may be further multiplied. Alternatively, for example, the relationship between the dimming rate and the lighting illuminance at the target point may be measured in advance, and the lighting illuminance may be estimated based on the measured relationship. For example, an illuminance sensor may be installed at the target point, and in a state where external light is blocked, the lighting illuminance may be measured by detecting the illuminance at the target point while changing the dimming rate of the lighting devices 14a and 14b, thereby measuring the relationship between the dimming rate and the lighting illuminance. Alternatively, for example, the relationship between the dimming rate and the illumination intensity may be estimated in advance by computer simulation or the like, and the illumination intensity may be estimated based on the estimated relationship.

[0021] The indoor illuminance calculation unit 36 ​​calculates the indoor illuminance based on the external light illuminance calculated by the external light illuminance calculation unit 34 and the illumination illuminance calculated by the illumination illuminance calculation unit 35. The indoor illuminance is the illuminance at a predetermined point in the indoor space 80, and is the sum of the external light illuminance and the illumination illuminance. For example, the indoor illuminance calculation unit 36 ​​calculates the indoor illuminance for each target point for which the external light illuminance calculation unit 34 has calculated the external light illuminance and the illumination illuminance calculation unit 35 has calculated the illumination illuminance. Specifically, for example, the indoor illuminance is calculated by adding the external light illuminance and the lighting illuminance for each target point.

[0022] The control unit 37 controls the lighting devices 14a and 14b based on the luminance ratio calculated by the luminance ratio calculation unit 33 and the indoor illuminance calculated by the indoor illuminance calculation unit 36. The control unit 37, for example, controls the lighting devices 14a and 14b separately. For example, the control unit 37 controls the lighting device 14a based on the luminance ratio calculated by the luminance ratio calculation unit 33 for an observation point set in the lighting area of ​​the lighting device 14a and the indoor illuminance calculated by the indoor illuminance calculation unit 36 ​​for a target point set in the lighting area of ​​the lighting device 14a. Similarly, the control unit 37 controls the lighting device 14b based on the luminance ratio calculated by the luminance ratio calculation unit 33 for an observation point set in the lighting area of ​​the lighting device 14b and the indoor illuminance calculated by the indoor illuminance calculation unit 36 ​​for a target point set in the lighting area of ​​the lighting device 14b.

[0023] Specifically, for example, the dimming ratios of the lighting devices 14a and 14b are set to the smallest possible value within a range in which the luminance ratio does not exceed a predetermined target luminance ratio and the indoor illuminance does not fall below a predetermined target illuminance. The target illuminance is set in advance to a value that does not fall below the minimum illuminance specified in, for example, the industrial hygiene standards. The target luminance ratio is set in advance to a value that will not cause the wall luminance to exceed 75% of the allowable wall luminance, regardless of the value of the average window luminance, based on the calculation formula for 75% of the allowable wall luminance described in Non-Patent Document 1, for example.

[0024] The control unit 37 changes the dimming rate based on, for example, the luminance ratio or the indoor illuminance calculated based on the illuminance detected by the external light illuminance sensors 11a and 11b and the wall illuminance sensor 12 at the current dimming rate. For example, if the luminance ratio is greater than the target luminance ratio or the indoor illuminance is less than the target illuminance, the dimming rate is increased slightly. If the dimming rate is increased, the wall luminance increases, which reduces the luminance ratio, and the lighting illuminance increases, which increases the indoor illuminance. Conversely, if the luminance ratio is smaller than the target luminance ratio and the room illuminance is greater than the target illuminance, the dimming rate is slightly reduced. Reducing the dimming rate increases the luminance ratio and reduces the room illuminance. By repeating this process, the dimming ratio of the lighting devices 14a and 14b is optimized.

[0025] The illumination control process 60 will be described with reference to FIG. In the lighting control process 60, the control device 13 controls the lighting device 14a. Note that the control for the lighting device 14b is similar, and therefore a description thereof will be omitted. The lighting control process 60 includes, for example, illuminance detection steps 61 and 65, an indoor illuminance calculation step 62, dimming rate increase steps 63 and 67, a dimming rate decrease step 64, and a luminance ratio calculation step 66.

[0026] In the illuminance detection step 61, the external light illuminance sensor 11a detects the external light illuminance.

[0027] In the indoor illuminance calculation step 62, the external light illuminance calculation unit 34 calculates the external light illuminance based on the external light illuminance detected by the external light illuminance sensor 11a in the illuminance detection step 61. Furthermore, the illumination illuminance calculation unit 35 calculates the illumination illuminance based on the dimming rate of the lighting device 14a. Then, based on the calculated external light illuminance and lighting illuminance, the indoor illuminance calculation unit 36 ​​calculates the indoor illuminance.

[0028] The dimming rate increasing step 63 is executed when the indoor illuminance calculated in the indoor illuminance calculating step 62 is smaller than the target illuminance. In the dimming rate increasing step 63, the control unit 37 increases the dimming rate of the lighting device 14a. Increasing the dimming rate increases the indoor illuminance, so the process returns to the illuminance detection step 61 to determine whether the indoor illuminance condition is met.

[0029] The dimming rate reduction step 64 is executed when the indoor illuminance calculated in the indoor illuminance calculation step 62 is greater than the upper limit of the target illuminance. The upper limit of the target illuminance is the target illuminance plus an allowable error. Since it is difficult to exactly match the indoor illuminance with the target illuminance, an allowable error is set. However, to prevent the indoor illuminance from falling below the target illuminance, an error is allowed only on the upper side, and not on the lower side. In the dimming rate decreasing step 64, the control unit 37 decreases the dimming rate of the lighting device 14a. By reducing the dimming rate, the indoor illuminance is reduced. Therefore, by returning to the illuminance detection step 61, it is determined whether the indoor illuminance has fallen within the allowable range.

[0030] The illuminance detection step 65 is executed when the indoor illuminance calculated in the indoor illuminance calculation step 62 is within the allowable range. As described above, the allowable range is a range that is equal to or greater than the target illuminance and equal to or less than the upper limit of the target illuminance. In the illuminance detection step 65, the external light illuminance sensor 11a detects the external light illuminance, and the wall surface illuminance sensor 12 detects the wall surface illuminance.

[0031] In the luminance ratio calculation step 66, the window surface luminance calculation unit 31 calculates the window surface luminance based on the external light illuminance detected by the external light illuminance sensor 11a in the illuminance detection step 65, and the wall surface luminance calculation unit 32 calculates the wall surface luminance based on the wall surface illuminance detected by the wall surface illuminance sensor 12 in the illuminance detection step 65.

[0032] The dimming rate increasing step 67 is executed when the luminance ratio calculated in the luminance ratio calculating step 66 is greater than the target luminance ratio. In the dimming rate increasing step 67, the control unit 37 increases the dimming rate of the lighting device 14a. Increasing the dimming rate reduces the brightness ratio, so the process returns to the illuminance detection step 65 to determine whether the brightness ratio condition is met.

[0033] If the luminance ratio calculated in the luminance ratio calculation step 66 is smaller than the target luminance ratio, the dimming rate is not reduced. This is because the required conditions are met in this state, namely, that the indoor illuminance does not fall below the target illuminance and that the luminance ratio does not exceed the target luminance ratio. If the dimming rate were reduced, not only would the luminance ratio increase, but the indoor illuminance would also decrease, which could result in the indoor illuminance falling below the target illuminance. Therefore, the dimming rate of the lighting device 14a is now adjusted to an optimum level.

[0034] Thereafter, since there is a possibility that the condition will no longer be satisfied due to a change in the intensity of external light 91, the process returns to illuminance detection step 61 and detects the illuminance again. Note that before returning to illuminance detection step 61, a predetermined interval (for example, 10 seconds) may be set.

[0035] In this way, the dimming rate may be adjusted first to satisfy the indoor illuminance condition, and then the dimming rate may be increased to satisfy the brightness ratio condition. Conversely, the dimming rate may be first adjusted to satisfy the luminance ratio condition, and then increased to satisfy the indoor illuminance condition. That is, the dimming rate is adjusted so that the luminance ratio falls within a predetermined allowable range, and then the dimming rate is increased so that the indoor illuminance does not fall below the target illuminance. The allowable range of the luminance ratio is, for example, a range above the target luminance ratio lower limit and below the target luminance ratio. Alternatively, the adjustment based on which condition is performed first may be changed depending on the intensity of external light. For example, when external light is strong, the luminance ratio condition is stricter, so the adjustment based on the luminance ratio condition is performed first. Conversely, when external light is weak, the indoor illuminance condition is stricter, so the adjustment based on the indoor illuminance condition is performed first. This reduces the number of times the dimming rate is changed until the adjustment is completed. Alternatively, the dimming rate may be adjusted by simultaneously determining the luminance ratio and the indoor illuminance. For example, if the luminance ratio is greater than the target luminance ratio or if the indoor illuminance is less than the target illuminance, the dimming rate is increased. Conversely, if the luminance ratio is less than the target luminance ratio lower limit and the indoor illuminance is greater than the target illuminance upper limit, the dimming rate is decreased.

[0036] As described above, the lighting device is controlled taking into consideration not only the indoor illuminance condition but also the luminance ratio condition, thereby preventing the indoor space from feeling too dark even when the indoor illuminance condition is met, thereby improving visual comfort. In addition, since the indoor illuminance is determined by separately calculating the external light illuminance and the lighting illuminance, it is possible to prevent the indoor illuminance from not satisfying the conditions due to the external light illuminance being detected excessively, and to ensure the brightness of the space.

[0037] The number of lighting devices to be controlled is not limited to two, and may be one, or three or more. When there are multiple lighting devices to be controlled, they may be controlled as a group rather than being controlled separately, or may be divided into multiple groups and controlled separately. When a group includes multiple lighting devices, instead of changing the dimming rate of each lighting device, the number of lighting devices that are turned on in the group may be changed, or both the dimming rate and the number of lighting devices that are turned on may be changed. When lighting devices are controlled for each group, it is not necessary to provide an external light illuminance sensor for each lighting device, and it is sufficient to provide at least one external light illuminance sensor for each group. The number of wall illuminance sensors is not limited to one, but may be two or more. In this case, for example, the wall luminance may be calculated based on the wall illuminance detected by the wall illuminance sensor installed on the wall that is most visible from the lighting area of ​​the lighting device or group to be controlled.

[0038] The above-described embodiment is an example for facilitating understanding of the present invention. The present invention is not limited thereto, and includes various modifications, changes, additions, or omissions without departing from the scope defined by the appended claims. This can be easily understood by those skilled in the art from the above description.

[0039] When using an illuminance sensor to detect illuminance and control lighting to maintain a constant indoor illuminance, it is necessary to prevent the illuminance sensor from over-detecting the illuminance of daylight, causing the actual indoor illuminance to fall below the target illuminance. This lighting control system ensures sufficient illuminance even in rooms where daylight is present, and also ensures the brightness of the space, thereby maintaining visual comfort. This prevents the illuminance sensor from detecting excessive daylight illuminance, even in spaces with a high aperture ratio, and prevents the actual indoor illuminance from falling below the target illuminance. Furthermore, even if the luminance of the window surface is high, the contrast between the luminance of the window surface and the interior of the room can prevent the room from appearing dark. For example, illuminance sensors are installed on the ceiling and wall surfaces. The indoor illuminance is calculated from the ceiling illuminance sensor and the dimming rate of the lighting fixture, and control is performed using the illuminance sensor. Next, the window surface luminance is calculated from the ceiling illuminance sensor, and the wall surface luminance is calculated from the wall illuminance sensor, and the luminance ratio (window surface luminance / wall surface luminance) is calculated. Finally, if the current luminance ratio is higher than the target luminance ratio, the dimming rate is increased. The target luminance ratio is set with reference to Non-Patent Document 1, etc. Various calculations and dimming rate control signals are performed within the lighting controller (control device). If the number of lighting control groups increases, an illuminance sensor is installed on the ceiling for each lighting control group. Unlike when controlling only the target illuminance, it is possible to prevent a large luminance contrast between the window surface and the interior of the room, ensuring brightness in the space and improving visual comfort. [Explanation of symbols]

[0040] 10 Lighting control system, 11a, 11b External light illuminance sensor, 12 Wall surface illuminance sensor, 13 Control device, 14a, 14b Lighting device, 31 Window surface luminance calculation unit, 32 Wall surface luminance calculation unit, 33 Luminance ratio calculation unit, 34 External light illuminance calculation unit, 35 Lighting illuminance calculation unit, 36 Indoor illuminance calculation unit, 37 Control unit, 60 Lighting control processing, 61, 65 Illuminance detection process, 62 Indoor illuminance calculation process, 63, 67 Dimming rate increase process, 64 Dimming rate decrease process, 66 Luminance ratio calculation process, 80 Indoor space, 81 Window, 82 Light receiving surface, 83 Ceiling, 84 Wall, 91 External light, 92a, 92b Reflected light,

Claims

1. an external light illuminance sensor that detects the illuminance of a surface hit by external light entering through a window; a wall illuminance sensor that detects the illuminance of a wall surface of the indoor space where the window is located; a window surface luminance calculation unit that calculates the window surface luminance of the window based on the illuminance detected by the external light illuminance sensor; a wall surface luminance calculation unit that calculates the wall surface luminance based on the illuminance detected by the wall surface illuminance sensor; a luminance ratio calculation unit that calculates a quotient by dividing the window surface luminance calculated by the window surface luminance calculation unit by the wall surface luminance calculated by the wall surface luminance calculation unit, thereby calculating a luminance ratio; a control unit that controls a lighting device installed in the indoor space based on the luminance ratio calculated by the luminance ratio calculation unit; A lighting control system comprising:

2. The control unit controlling the lighting device so that the luminance ratio calculated by the luminance ratio calculation unit does not exceed a predetermined target luminance ratio; The lighting control system of claim 1 .

3. an external light illuminance calculation unit that calculates an indoor illuminance due to external light entering through the window based on the illuminance detected by the external light illuminance sensor; an illumination illuminance calculation unit that calculates an indoor illuminance by the illumination device based on a dimming rate of the illumination device; an indoor illuminance calculation unit that calculates an overall indoor illuminance by adding the indoor illuminance calculated by the lighting illuminance calculation unit to the indoor illuminance calculated by the external light illuminance calculation unit; Further provided with The control unit controlling the lighting device based on the luminance ratio calculated by the luminance ratio calculation unit and the indoor illuminance calculated by the indoor illuminance calculation unit; 3. The lighting control system according to claim 1 or 2.

4. The control unit controlling the lighting device so that the indoor illuminance calculated by the indoor illuminance calculation unit does not fall below a predetermined target illuminance; The lighting control system of claim 3.

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