Lighting control system and lighting control method

Abstract

To provide a lighting control system and a lighting control method capable of controlling lighting considering the brightness felt by people in a room.SOLUTION: An indoor lighting control system 1 includes a lighting fixture 2 installed in a room, a window surface luminance sensor 3 that detects the luminance of the window surface or the amount of light correlated with the luminance as a first detection value, a ceiling surface luminance sensor 4 that detects the luminance of the ceiling surface or the amount of light correlated with the luminance as a second detection value, and a control device 5 that calculates the current brightness of the indoor space from the first detection value and the second detection value using a mathematical formula with the brightness evaluation of the indoor space as an objective variable, and controls the lighting fixture on the basis of the calculated current brightness, and the control device 5 uses either the formula for the window surface or the formula for the wall surface according to a condition in the room to evaluate the current brightness of the space in the room.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a lighting control system and a lighting control method. [Background technology]

[0002] Conventional lighting control methods were based on whether the illuminance of a certain surface (desk surface) in a space met the design illuminance. Lighting control methods based on the brightness of the space are also being developed (see, for example, Patent Documents 1 and 2). The technology described in Patent Document 1 relates to the control of blinds installed on a window surface. In this technology, the outdoor luminance distribution directly facing the window surface is photographed, and the angle of the blinds is controlled so that the window surface luminance is not excessive. Furthermore, the window surface luminance distribution calculated from the outdoor luminance distribution is used to obtain the distribution of indices of brightness and glare, and the blinds are controlled so that the window surface luminance distribution or the distribution of indices of brightness and glare falls within an acceptable range. The technology described in Patent Document 2 is a method for creating a control pattern based on the amount of daylight introduced into a space and a target sense of brightness (NSB value). For example, Patent Document 2 shows a method for creating a lighting control pattern that satisfies the NSB value, which represents the sense of brightness, according to the amount of daylight introduced into a space that has windows that can introduce daylight. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-023428 A [Patent Document 2] JP 2018-181613 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional lighting control does not take into consideration the overall amount of light seen by people in a room (especially people working in offices). As a result, the lighting environment seen by people in the room is sometimes too dark or too bright, which is an issue. For example, the technology of Patent Document 1 has the problem that it only captures and controls images of the direction directly facing the window, and does not consider other directions. In addition, it requires a luminance camera, which poses problems of the need for a sophisticated system and costs for installing the luminance camera and processing the obtained data. Furthermore, the technology of Patent Document 2 does not take into consideration that the brightness perceived by an occupant in a room differs depending on the object in the occupant's line of sight. From this perspective, the present invention provides a lighting control system and a lighting control method that can control lighting taking into consideration the brightness perceived by occupants. [Means for solving the problem]

[0005] A lighting control system according to the present invention is an indoor lighting control system that includes a lighting fixture installed in the room, a window surface luminance sensor that detects the luminance of a window surface or an amount of light correlated with the luminance as a first detection value, a ceiling surface luminance sensor that detects the luminance of a ceiling surface or an amount of light correlated with the luminance as a second detection value, and a control device. The control device calculates the current brightness of the indoor space from the first detection value and the second detection value using a formula with the brightness evaluation of the indoor space as a target variable, and controls the lighting device based on the calculated current brightness. The formula has explanatory variables which are the luminance of the window surface, the luminance of the ceiling surface, and the solid angles of the window surface and the ceiling surface, and includes a formula for the window surface orientation which includes a coefficient taking into account the brightness perceived by an occupant facing the window surface, and a formula for the wall surface orientation which includes a coefficient taking into account the brightness perceived by an occupant facing the wall surface. The control device uses either the window surface orientation formula or the wall surface orientation formula depending on the indoor situation to evaluate the current brightness of the indoor space.

[0006] The formula is, for example, as shown below.

number

[0007] The window surface orientation formula and the wall surface orientation formula may be classified based on the following three conditions so that there are a total of six formulas with different coefficients. (1) When the window surface luminance is equal to or greater than the reference window surface luminance (2) When the window surface luminance is less than the reference window surface luminance and the ratio of the window surface luminance to the ceiling surface luminance is equal to or greater than the reference luminance ratio. (3) When the window surface luminance is smaller than the reference window surface luminance and the ratio of the window surface luminance to the ceiling surface luminance is smaller than the reference luminance ratio In this way, it is possible to evaluate the brightness perceived by the occupants in a more detailed manner, thereby providing a more suitable lighting environment for the occupants.

[0008] If the room is divided into multiple areas for which dimming is controlled, the control device may calculate the brightness in multiple directions at a representative point of each divided area for each direction using either the window-facing formula or the wall-facing formula, and control the dimming of the area based on the brightness evaluation in the direction with the lowest brightness. In this way, even if there are multiple occupants in a room and each occupant is facing in a different direction, a lighting environment that is not too dark for most of the occupants can be provided.

[0009] The window surface luminance sensor and the ceiling surface luminance sensor may be installed on a ceiling. The window surface luminance sensor has a first illuminance sensor element that detects illuminance in the direction of a floor surface, a housing that accommodates the first illuminance sensor element, and an attachment attached to the housing. The attachment has a light reflecting portion that guides light arriving from the direction of the window surface to the first illuminance sensor element. The control device has information indicating a relationship between the amount of light detected by the window surface luminance sensor and the luminance of the window surface, and calculates the luminance of the window surface based on the information. The ceiling surface luminance sensor includes a second illuminance sensor element that detects illuminance in the direction of the floor surface, a housing that contains the second illuminance sensor element, and a translucent cover attached to the housing. Light that passes through the cover is guided to the second illuminance sensor element. The control device has information indicating a relationship between the amount of light detected by the ceiling surface luminance sensor and the luminance of the ceiling surface, and calculates the luminance of the ceiling surface based on the information.

[0010] A lighting control method according to the present invention is a method for controlling lighting in a room, in which a lighting fixture, a window surface luminance sensor that detects a luminance of a window surface or an amount of light correlated with the luminance as a first detection value, and a ceiling surface luminance sensor that detects a luminance of a ceiling surface or an amount of light correlated with the luminance as a second detection value are installed. This lighting control method includes a detection step of detecting the first detection value and the second detection value using the window surface luminance sensor and the ceiling surface luminance sensor, and a control step of calculating a current brightness of the indoor space from the first detection value and the second detection value using a formula having a brightness evaluation of the indoor space as a target variable, and controlling the lighting device based on the calculated current brightness. The formula has explanatory variables which are the luminance of the window surface, the luminance of the ceiling surface, and the solid angles of the window surface and the ceiling surface, and includes a formula for the window surface orientation which includes a coefficient taking into account the brightness perceived by an occupant facing the window surface, and a formula for the wall surface orientation which includes a coefficient taking into account the brightness perceived by an occupant facing the wall surface. In the control step, the current brightness of the indoor space is evaluated using either the window surface orientation formula or the wall surface orientation formula depending on the indoor situation. According to the lighting control method of the present invention, the indoor space can be evaluated taking into consideration the brightness perceived by the occupants, and therefore it is possible to provide an appropriate lighting environment that is neither too dark nor too bright for the occupants. In other words, it is possible to perform detailed lighting control according to the line of sight of the occupants. Effect of the Invention

[0011] According to the present invention, lighting can be controlled taking into consideration the brightness perceived by occupants. [Brief description of the drawings]

[0012] [Figure 1] 1 is an overall configuration diagram of a lighting control system according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an external view of a window surface luminance sensor. [Diagram 3] FIG. 2 is an external view of a ceiling surface luminance sensor. [Figure 4] 1A to 1C are diagrams for explaining an attachment in a window surface luminance sensor, where (a) is a perspective view, (b) is a front view, and (c) is a side view. [Diagram 5] 11A and 11B are diagrams for explaining the function of an attachment in a window surface luminance sensor. [Figure 6] FIG. 4 is a diagram for explaining a brightness approximation formula used in the lighting control according to the embodiment of the present invention. [Figure 7] 1 is an image diagram to explain the field of view of an occupant. (a) shows the case where the occupant faces the window, and (b) shows the case where the occupant faces the wall. [Figure 8] 1 is an example flowchart of a lighting control method according to an embodiment of the present invention. [Figure 9] FIG. 13 is an image diagram of a room to be controlled. [Figure 10]13 is a flowchart illustrating another lighting control method, in which (a) to (f) correspond to first to sixth dimming sections. [Figure 11] This figure explains the contents of an experiment conducted to verify the formula used for the perceived brightness value of a space (BR value), where (a) is a table showing an overview of the experimental space, and (b) is a schematic drawing of the experimental space. [Figure 12] 5A and 5B are diagrams for explaining changes in the coefficient of determination of a prediction formula, in which (a) shows changes in the coefficient of determination due to the average luminance of a window surface, and (b) shows changes in the coefficient of determination due to the luminance ratio. [Figure 13] This is a plot of the evaluation value and predicted value of the brightness of the space facing a window. (a) is the case when the window surface luminance is 1500 cd / m2 or more, (b) is the case when the window surface luminance is less than 1500 cd / m2 and the luminance ratio is 0.7 or more, and (c) is the case when the luminance ratio is less than 0.7. [Figure 14] This figure explains the relationship between the estimated coefficient of each variable and the p-value in the space of window surface orientation. (a) is the case where the window surface luminance is 1500 cd / m2 or more, (b) is the case where the window surface luminance is less than 1500 cd / m2 and the luminance ratio is 0.7 or more, and (c) is the case where the luminance ratio is less than 0.7. [Figure 15] This is a plot of the evaluated and predicted brightness values ​​for spaces facing a wall. (a) is the case when the window surface luminance is 1500 cd / m2 or more, (b) is the case when the window surface luminance is less than 1500 cd / m2 and the luminance ratio is 0.7 or more, and (c) is the case when the luminance ratio is less than 0.7. [Figure 16] This is a diagram to explain the relationship between the estimated coefficient of each variable and the p-value in a space facing a wall, where (a) is the case where the window surface luminance is 1500 cd / m2 or more, (b) is the case where the window surface luminance is less than 1500 cd / m2 and the luminance ratio is 0.7 or more, and (c) is the case where the luminance ratio is less than 0.7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, the embodiment of the present invention will be described in detail with reference to the drawings. Each drawing is merely a schematic illustration to allow a sufficient understanding of the present invention. Therefore, the present invention is not limited to the illustrated examples. In each drawing, common or similar components are denoted by the same reference numerals, and duplicated explanations thereof will be omitted. <Configuration of lighting control system according to embodiment> A lighting control system 1 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is an overall configuration diagram of the lighting control system 1. The lighting control system 1 is a system that controls indoor lighting. The lighting control system 1 provides a suitable lighting environment that is neither too dark nor too bright by performing control that takes into account the brightness that people perceive in a room. Note that the "brightness that people perceive" is expressed by "luminance" rather than "illuminance," and it is generally known that appropriate control of ambient lighting is necessary to maintain the right brightness in a space.

[0014] The purpose and shape of the room in the lighting control system 1 are not particularly limited, and the lighting control system 1 can be applied to lighting control of various rooms. The room may be, for example, a building such as a building or a house (including a room that is a part of a building). In this embodiment, the shape of the room is assumed to be a space covered by a floor on the bottom, a ceiling on the top, and multiple walls on the sides. In addition, the purpose of the room is assumed to be office work. Therefore, the person in the room is an office worker who performs desk work, and the position of the seat where the office worker performs work in the room and the line of sight of the office worker while seated are determined in advance. As shown in FIG. 1, a window is formed in the wall of the room, and natural light enters the room from the window. The wall surface on which the window is formed is called a "window surface."

[0015] The lighting control system 1 includes a lighting fixture 2, a window surface luminance sensor 3, a ceiling surface luminance sensor 4, and a control device 5. The lighting fixture 2, the window surface luminance sensor 3, and the ceiling surface luminance sensor 4 are installed indoors, and the installation location of the control device 5 is not particularly limited. In this embodiment, the lighting fixture 2, the window surface luminance sensor 3, and the ceiling surface luminance sensor 4 are installed on the ceiling, and the control device 5 is installed outdoors (for example, in a control room of a building). The lighting fixture 2 is a fixture that illuminates a room with light, for example, ambient lighting. There is no limit to the number of lighting fixtures 2 installed in a room, and there may be one or more. The lighting fixture 2 is dimmable, and the amount of light it emits can be changed in stages. The lighting fixture 2 receives a control signal from the control device 5 and adjusts the amount of light it emits, for example, according to a dimming rate.

[0016] The window surface luminance sensor 3 is a sensor (detection means) that detects the luminance of the window surface. The window surface luminance sensor 3 is installed at a location where it can detect the luminance of the window surface. There is no limitation on the method by which the window surface luminance sensor 3 detects the luminance of the window surface. The window surface luminance sensor 3 may detect the amount of light that correlates with the luminance of the window surface, and calculate the luminance of the window surface from the detected amount of light. There is no limitation on the location where the luminance calculation is performed, and for example, the control device 5 may calculate the luminance. The window surface luminance sensor 3 transmits the detected detection value (referred to as the "first detection value") to the control device 5. As shown in Fig. 2, in this embodiment, it is assumed that the window surface luminance sensor 3 is substituted with an illuminance sensor, and the luminance of the window surface is calculated based on the detection value detected by the illuminance sensor. Fig. 2 is an external view of the window surface luminance sensor 3. Although details will be described later, the same is true for the ceiling surface luminance sensor 4, and it is assumed that the ceiling surface luminance sensor 4 is substituted with an illuminance sensor (see Fig. 3). Fig. 3 is an external view of the ceiling surface luminance sensor 4. In other words, in this embodiment, the luminance of the window surface and ceiling surface can be calculated by attaching accessories designed for each detection target to an illuminance sensor that is generally installed on the ceiling.

[0017] The configuration of the window surface luminance sensor 3 will be described with reference to Fig. 2. The window surface luminance sensor 3 includes a sensor main body 31 and an attachment 32. When the sensor main body 31 is used alone without the attachment 32 attached, it is capable of detecting the illuminance in the direction of the floor surface. The sensor main body 31 has a disk-shaped housing 31a and a light receiving section 31c (first illuminance sensor element). A recess 31b that receives light into the housing 31a is formed on the floor side of the housing 31a, and the light receiving section 31c is disposed in the recess 31b. The light receiving section 31c is an electronic component that converts the received light into an electrical signal. The light received in the recess 31b reaches the light receiving section 31c. The attachment 32 is a component that changes the direction of light received by the light receiving portion 31c toward the window, and is installed by being fitted into the recess 31b.

[0018] The configuration of the attachment 32 will be described with reference to Fig. 4. Fig. 4 is a diagram for explaining the attachment 32, where (a) is a perspective view, (b) is a front view, and (c) is a side view. Here, "up and down," "front and back," and "left and right" in the explanation of the attachment 32 follow the arrows in Fig. 4. Note that these directions are determined for the convenience of explanation, and do not limit the present invention. The attachment 32 has a through hole 32a through which light passes. One opening 32aa of the through hole 32a is formed on the front side, and the other opening 32ab is formed on the upper side. The opening 32aa on the front side serves as an entrance for taking in light, and the opening 32ab on the upper side serves as an exit for emitting light. A light reflecting portion 32m is installed in the through hole 32a. The light reflecting portion 32m is, for example, a mirror, and is installed so as to reflect the light entering from the opening 32aa on the front side upward, as shown in FIG. 5. FIG. 5 is a diagram for explaining the function of the attachment 32. The light reflected by the light reflecting portion 32m reaches the light receiving portion 31c through the opening 32ab on the upper side. The attachment 32 is installed so that the opening 32aa, which is the entrance, faces the window surface. As a result, the light reflecting portion 32m serves to guide the light arriving from the direction of the window surface to the light receiving portion 31c.

[0019] The configuration of the ceiling surface luminance sensor 4 will be described with reference to FIG. 3. The ceiling surface luminance sensor 4 is a sensor (detection means) that detects the luminance of the ceiling surface. The ceiling surface luminance sensor 4 is installed at a location where it can detect the luminance of the ceiling surface. There is no limitation on the method by which the ceiling surface luminance sensor 4 detects the luminance of the ceiling surface. The ceiling surface luminance sensor 4 may detect the amount of light that correlates with the luminance of the ceiling surface, and calculate the luminance of the ceiling surface from the detected amount of light. There is no limitation on the location where the luminance is calculated, and for example, the control device 5 may calculate the luminance. The ceiling surface luminance sensor 4 transmits the detected detection value (referred to as the "second detection value") to the control device 5. As described above, in this embodiment, it is assumed that the ceiling surface luminance sensor 4 is replaced with an illuminance sensor, and the luminance of the ceiling surface is calculated based on the detection value detected by the illuminance sensor.

[0020] As shown in Fig. 3, the ceiling surface luminance sensor 4 comprises a sensor body 41 and a cover 42. The sensor body 41 is the same as the sensor body 31 of the window surface luminance sensor 3, and when used alone without the cover 42, it is possible to detect the illuminance in the direction of the floor surface. The window surface luminance sensor 3 and the ceiling surface luminance sensor 4 differ in the cover 42 that is an accessory. The sensor main body 41 has a disk-shaped housing 41a and a light receiving section (second illuminance sensor element) (not shown). A recess 41b that takes in light into the housing 41a is formed on the floor side of the housing 41a, and the light receiving section is disposed in the recess 41b. The light receiving section is an electronic component that converts the received light into an electrical signal. The light taken in by the recess 41b reaches the light receiving section. The cover 42 is a component for smoothing the light received by the light receiving unit so as to make it easier to calculate the luminance of the ceiling surface. The cover 42 in this embodiment is plate-shaped (or sheet-shaped) and is installed so as to cover (close) the recess 41b. The cover 42 is, for example, white and semi-transparent, and diffuses the light passing through it. The light passing through the cover 42 is smoothed by being diffused, and becomes light suitable for calculating the luminance of the ceiling surface.

[0021] The control device 5 shown in Fig. 1 is a device that controls the lighting fixtures 2 to realize a comfortable lighting environment indoors. The control device 5 is a server installed in, for example, a large commercial building, a hospital, a factory, etc. The control device 5 may be composed of multiple devices (for example, an area controller and a floor controller, etc.). The control device 5 includes a storage unit and a control unit. The storage unit is composed of a storage medium such as a RAM (Random Access Memory), a ROM (Read Only Memory), a HDD (Hard Disk Drive), a flash memory, etc. The storage unit stores information necessary for controlling the lighting. The control unit is realized by a program execution process by a CPU (Central Processing Unit), a dedicated circuit, etc. When the control unit is realized by a program execution process, the control device 5 has a program (lighting control program) necessary for realizing lighting control. Instead of or in addition to the storage unit, the control unit may acquire information necessary for controlling the lighting via, for example, a network. The control device 5 is connected to the lighting fixture 2, the window surface luminance sensor 3, and the ceiling surface luminance sensor 4 so as to be able to transmit and receive data. The connection may be either wired or wireless.

[0022] The control device 5 obtains a detection value (first detection value) detected by the window surface luminance sensor 3. The detection value of the window surface luminance sensor 3 may be the luminance of the window surface, an amount of light correlated to the luminance of the window surface, etc. The control device 5 also obtains a detection value (second detection value) detected by the ceiling surface luminance sensor 4. The detection value of the ceiling surface luminance sensor 4 may be the luminance of the ceiling surface, an amount of light correlated to the luminance of the ceiling surface, etc. The control device 5 controls the lighting fixtures 2 based on the detection values ​​of the window surface luminance sensor 3 and the ceiling surface luminance sensor 4. The control device 5 performs control according to the brightness perceived by the occupants, and in particular performs control according to the brightness in the line of sight of the occupants (i.e., the amount of light (luminance) entering the field of vision of the occupants). For example, the control device 5 sets a representative (which may be a virtual occupant) for each area to be controlled, and performs control according to the brightness in the line of sight of the representative. The control device 5 may also set multiple representatives facing different directions, and perform control based on the brightness in the line of sight of each of the multiple representatives (for example, control according to the representative who perceives the lowest brightness). Details will be described later. The control device 5 transmits a control signal related to the lighting control (for example, a dimming rate) to the lighting fixtures 2. It is preferable that the control device 5 calibrates the detection value of the window surface luminance sensor 3 and the detection value of the ceiling surface luminance sensor 4. The control device 5 stores information necessary for the calibration in, for example, a storage unit.

[0023] (About the principles of lighting control) The principle of lighting control according to this embodiment will be described with reference to Fig. 6 and Fig. 7. Fig. 6 is a diagram for explaining a brightness approximation formula used in lighting control according to this embodiment. Fig. 7 is an image diagram for explaining the field of view of an occupant, where (a) shows a case where an occupant faces a window, and (b) shows a case where an occupant faces a wall. It is known that a person's sense of brightness is affected by the amount of light (luminance) entering the field of vision. Experiments have also shown that the brightness felt by people indoors is most easily affected by the brightness of the "window surface" and the "ceiling surface." In this embodiment, the current brightness of the indoor space is calculated using the following formula (A), which uses the brightness evaluation (sensation value) of the indoor space as the objective variable and the luminance of the window surface, the luminance of the ceiling surface, and the solid angle of the window surface and the ceiling surface as explanatory variables.

[0024]

number

[0025] In the above formula (A), "BR" is the "sensation value of the brightness of the space," "a, b" are coefficients (constants), "L" is luminance, and "ω" is a solid angle. Also, the subscript "w" indicates that it is a window surface, and "c" indicates that it is a ceiling surface. A specific example of the explanatory variables in the above formula (A) is shown in Figure 6. In Figure 6, we assume that the occupants are workers sitting at their desks and doing their work. Therefore, the height of the occupants' viewpoints is the height of the general line of sight of a worker sitting down (for example, 1.2 m from the floor).

[0026] The inventors have found that it is effective to use different values ​​for the coefficients "a, b" depending on the difference in the line of sight of the occupants when calculating the perceived brightness value (BR value) of a space using the above formula (A). In particular, when considering the configuration of a typical room and the arrangement of seats, the inventors have noticed that in most cases the occupants are either facing the window or the wall, and have found that it is effective to use different coefficients "a, b" for "a state in which the occupant faces directly on the window (see Fig. 7(a))" and "a state in which the occupant faces directly on the wall (for example, a state in which the occupant faces sideways at 90° to the window) (see Fig. 7(b))". Formula (A) used when facing a window as shown in Figure 7(a) is specifically referred to as "formula (B) for facing a window." Formula (B) for facing a window uses coefficients that take into account the brightness felt by people facing a window. On the other hand, formula (A) used when facing a wall as shown in Figure 7(b) is specifically referred to as "formula (C) for facing a wall." When the window surface luminance is greater than the reference window surface luminance, the coefficients used in formula (B) for facing a window tend to be smaller than those in formula (C) for facing a wall.

[0027] The inventors have also found that it is effective to use different values ​​for the coefficients "a, b" in the above formula (A) depending on the "window surface luminance Lw" and the "ratio of the window surface luminance Lw to the ceiling surface luminance Lc (sometimes simply referred to as "luminance ratio")." In this embodiment, classification is made based on the following three conditions, and different values ​​for the coefficients "a, b" are used for each classification. (1) When the window surface luminance Lw is equal to or higher than the reference window surface luminance Lw_standard. (2) When the window surface luminance Lw is smaller than the reference window surface luminance Lw_standard, and the ratio of the window surface luminance Lw to the ceiling surface luminance Lc is equal to or higher than the reference luminance ratio Lw / c_standard. (3) When the window surface luminance Lw is smaller than the reference window surface luminance Lw_standard, and the ratio of the window surface luminance Lw to the ceiling surface luminance Lc is smaller than the reference luminance ratio Lw / c_standard.

[0028] Furthermore, by combining the classification based on "the difference in the line-of-sight direction of the occupants" and the classification based on "the window surface luminance" and "the ratio of the window surface luminance to the ceiling surface luminance (luminance ratio)", more detailed control based on the brightness felt by the occupants can be performed. By combining the above two classifications, a total of six mathematical formulas (Formulas (1) to (6)) with different coefficients shown below are formed.

[0029] (BR value calculation formula in the state facing the window) · When the window surface luminance Lw ≥ Lw_standard, Formula (1) is used. BR = Aw_win_1·log10(Lw·ωw) + Ac_win_1·log10(Lc·ωc) + B_win_1 ·· Formula (1) · When the window surface luminance Lw < Lw_standard and Lw / Lc ≥ Lw / c_standard, Formula (2) is used. BR = Aw_win_2·log10(Lw·ωw) + Ac_win_2·log10(Lc·ωc) + B_win_2 ·· Formula (2) · When the window surface luminance Lw < Lw_standard and Lw / Lc < Lw / c_standard, Formula (3) is used. BR = Aw_win_3·log10(Lw·ωw) + Ac_win_3·log10(Lc·ωc) + B_win_3 ·· Formula (3) Here, "BR: predicted brightness value", "Aw: window area coefficient", "Ac: ceiling area coefficient", "B: coefficient", "Lw: window brightness", "Lc: ceiling brightness", "ω: solid angle", "Lw_standard: reference window brightness", "Lw / c_standard: reference brightness ratio". Also, the meanings of the subscripts are "w: window surface", "c: ceiling surface", "_win: window orientation", "_1: condition 1", "_2: condition 2", "_3: condition 3".

[0030] (BR value calculation formula in the state facing the wall surface (for example, the horizontal state at 90° to the window surface)) · When the window brightness Lw ≥ Lw_standard, formula (4) is used. BR = Aw_wall_1·log10(Lw·ωw) + Ac_wall_1·log10(Lc·ωc) + B_wall_1 ·· formula (4) · When the window brightness Lw < Lw_standard and Lw / Lc ≥ Lw / c_standard, formula (5) is used. BR = Aw_wall_2·log10(Lw·ωw) + Ac_wall_2·log10(Lc·ωc) + B_wall_2 ·· formula (5) · When the window brightness Lw < Lw_standard and Lw / Lc < Lw / c_standard, formula (6) is used. BR = Aw_wall_3·log10(Lw·ωw) + Ac_wall_3·log10(Lc·ωc) + B_wall_3 ·· formula (6) Here, "BR: predicted brightness value", "Aw: window area coefficient", "Ac: ceiling area coefficient", "B: coefficient", "Lw: window brightness", "Lc: ceiling brightness", "ω: solid angle", "Lw_standard: reference window brightness", "Lw / c_standard: reference brightness ratio". Also, the meanings of the subscripts are "w: window surface", "c: ceiling surface", "_wall: wall orientation", "_1: condition 1", "_2: condition 2", "_3: condition 3".

[0031] Tables 1 and 2 show examples of coefficients used in the above formulas (1) to (6). The coefficients used in formulas (1) to (6) and the thresholds for case classification based on the window surface luminance ratio to the window surface luminance and ceiling surface luminance were derived from a verification experiment of brightness by subjects. In the experiment, different light environment spaces were created in the office space that was the subject of the experiment, depending on the window blind angle and weather conditions. Under the different light environment conditions, subjects, from their seats facing the window and the wall facing 90 degrees to the side from the window, memorized the light environment in a box adjusted to a separately prepared standard brightness (300lx) as "100" and evaluated the brightness in the experimental space with a positive value in comparison. This value was statistically analyzed for each direction the subject faced, and the formula and coefficients for estimating the brightness of the space evaluated by the subject were derived. Details of the experiment will be described later.

[0032] [Table 1]

[0033] [Table 2]

[0034] <Operation of the lighting control system according to the embodiment> The operation of lighting control system 1 according to an embodiment will be described with reference to Fig. 8. Fig. 8 is an example of a flowchart of a lighting control method in lighting control system 1. The process of the flowchart shown in Fig. 8 may be executed at any timing, for example, or may be executed repeatedly at predetermined intervals. The control device 5 acquires information about the brightness of the room required for lighting control (step S1). Specifically, it acquires a detection value (referred to as a "first detection value") detected from the window surface luminance sensor 3 (step S1A), and also acquires a detection value (referred to as a "second detection value") detected from the ceiling surface luminance sensor 4 (step S1B). The detection value here is, for example, the amount of light correlated with the luminance of the window surface or the ceiling surface.

[0035] Next, the control device 5 calculates the window surface luminance based on the detection value detected by the window surface luminance sensor 3 (step S2A), and also calculates the ceiling surface luminance based on the detection value detected by the ceiling surface luminance sensor 4 (step S2B). The control device 5 has, for example, information associating the amount of light detected by the window surface luminance sensor 3 with the window surface luminance (or a formula for calculating the window surface luminance from the amount of light detected by the window surface luminance sensor 3, etc.). Similarly, the control device 5 has, for example, information associating the amount of light detected by the ceiling surface luminance sensor 4 with the ceiling surface luminance (or a formula for calculating the ceiling surface luminance from the amount of light detected by the ceiling surface luminance sensor 4, etc.).

[0036] Next, the control device 5 calculates the current BR value based on the detection value of the sensor using the above formula (A) (step S3). The control device 5 determines formulas (1) to (6) for calculating the BR value based on, for example, the line of sight direction of a person in the room (which may be the representative), the "window surface luminance" and the "ratio of the window surface luminance to the ceiling surface luminance (luminance ratio)", and calculates the current BR value using the determined formula. Here, the method of identifying the gaze direction of the occupant is not particularly limited, and various techniques can be used. For example, the gaze direction of the occupant may be identified from the startup status of a PC (Personal Computer) installed in the room. Also, the relationship between the occupant and the seat may be held in advance, and the occupant may be identified from entry and exit information to identify the gaze direction. Also, a camera may be installed in the room, and the gaze direction of the occupant may be identified by analyzing the captured image of the camera. In this way, the lighting control system 1 may include a detection means for detecting the gaze direction of the occupant. Also, the area to be controlled and the formulas (1) to (6) for calculating the BR value may be associated in advance, and the BR value may be calculated using a formula based on the association. The association between the area to be controlled and the formulas (1) to (6) for calculating the BR value may be set for each day of the week or time period. This control is effective, for example, when there are certain occupants for each day of the week or time period. The gaze direction of the occupant described here is an example of the "situation in the room."

[0037] Next, the control device 5 controls the dimming rate based on the relationship between the calculated current BR value and the target BR value. Specifically, if the current BR value is greater than the target BR value ("Yes" in step S4), the control device 5 reduces the dimming rate (step S5). On the other hand, if the current BR value is not greater than the target BR value ("No" in step S4), the control device 5 increases the dimming rate (step S6). Then, the control device 5 transmits the dimming rate determined in step S5 or step S6 to the lighting device 2 as a control signal. This completes the series of operations related to lighting control.

[0038] Next, another method of calculating the BR value of the controlled area will be described with reference to Fig. 9 and Fig. 10. Fig. 9 is an image diagram of a room to be controlled. Fig. 10 is an example of a flowchart of another lighting control method in the lighting control system 1. As shown in Fig. 9, six dimming sections A1 to A6 are set in the room space. The dimming sections A1 to A6 are units of lighting control and can be dimmed individually. The dimming sections A1 to A6 are areas where, for example, multiple office workers' seats are located. Two window surface luminance sensors 31, 32 and six ceiling surface luminance sensors 41-46 are installed in the room space. L-shaped windows are provided in the room on the lower and left side of the paper in FIG. 9, and one window surface luminance sensor 31 is arranged facing the lower window, and the other window surface luminance sensor 32 is arranged facing the left window. The ceiling surface luminance sensors 41-46 are arranged one by one in each of the dimming sections A1-A6. That is, one ceiling surface luminance sensor is arranged in one dimming section. In addition, reference positions P1-P6 are set for each of the dimming sections A1-A6. The reference positions P1-P6 are positions that serve as references for calculating the BR value, and may be any positions.

[0039] The control device 5 calculates the BR values ​​for a total of four directions (the "p direction", "q direction", "r direction", and "s direction") at each of the reference positions P1 to P6 at 90° intervals. For example, the control device 5 calculates the BR value when looking in the p direction at the reference position P1 as "BR 1-p ", and "BR 1-q ", and "BR 1-r ", and "BR 1-s The same is true for the reference positions P2 to P6. In calculating the BR value, consideration is given to "whether each direction faces the window or the wall," as well as the "window surface luminance" and the "ratio of the window surface luminance to the ceiling surface luminance (luminance ratio)," and the corresponding one of the above-mentioned formulas (1) to (6) is used. For example, assume that the BR value for the p direction at the reference position P1 is to be calculated. Since the p direction at the reference position P1 faces the window, the formulas (1) to (3) that match the conditions such as the window surface luminance are used. Next, assume that the BR value for the r direction at the reference position P1 is to be calculated. Since the r direction at the reference position P1 faces the wall, the formulas (4) to (6) that match the conditions such as the window surface luminance are used.

[0040] The control device 5 controls the dimming rate of each of the dimming sections A1 to A6 based on the calculated BR values ​​for the four directions. The control device 5 uses, for example, the lowest BR value among the calculated BR values ​​for the four directions as a control standard. In other words, the control device 5 dims the lighting fixtures 2 in the dimming section so that the brightness in the line of sight direction where the BR value is the lowest and perceived as dark is just right. An example of control based on the lowest BR value among the four directions is shown in FIG. 10. (a) to (f) of FIG. 10 correspond to the first to sixth dimming sections A1 to A6, and are processes equivalent to steps S3 to S7 of FIG. 8. For example, the dimming section A1 will be described as an example. The control device 5 determines the BR value "BR 1-p ", and "BR 1-q ", and "BR 1-r ", and "BR 1-s" and the minimum of the four is set as the current value for dimming section A1. Next, control device 5 decreases the dimming rate if the current BR value of dimming section A1 is greater than the target BR value, and increases the dimming rate if the current BR value is not greater than the target BR value. Then, control device 5 transmits the determined dimming rate as a control signal to lighting fixture 2 in dimming section A1, and dims lighting fixture 2.

[0041] As described above, the lighting control system 1 can evaluate the indoor space taking into account the brightness perceived by the occupants, and can provide a lighting environment that is neither too dark nor too bright for the occupants. In other words, it enables detailed lighting control according to the line of sight of the occupants. Furthermore, the lighting control system 1 can be constructed using an illuminance sensor that is generally installed on the ceiling. In other words, it does not require the installation of a luminance camera or an advanced system for data processing, and is based on a conventional brightness sensor and a controller that controls the output of the lighting, making it possible to realize a simple system at low cost.

[0042] <Brightness verification experiment by subjects> The inventor conducted an experiment to verify the formula used for the perceived value of spatial brightness (BR value), which will now be described. Figure 11 is a diagram for explaining the content of the experiment conducted to verify the formula used for the perceived value of spatial brightness (BR value), where (a) is a table showing an overview of the experimental space, and (b) is a schematic drawing of the experimental space. The experiment shown in Figure 11 evaluates the brightness felt when the subject faces a window surface and when the subject faces a wall surface. The experiment was conducted on January 8th and 9th, 2020 (weather: fine) in an experimental space with a window (W: 4.3m × D: 9.7m × H2.7m) as shown in Figure 11(b). The experiment was conducted in two time periods, morning and night, with three slat angles for the Venetian blinds installed on the windows: horizontal, 45 degrees, and closed, and three desk illuminance levels at the center of the experimental space: 200lx, 400lx, and 750lx. The subjects were asked to evaluate the brightness of the space under a total of 18 conditions. The subjects were asked to evaluate the brightness of the experimental space using the ME method, with the reference space being set as "100", as a positive integer. For the luminance measurement, a camera using a circular fisheye lens was installed at the viewpoint position of each evaluation seat, and the luminance distribution was measured at 5-minute intervals. The subjects were 12 students in their early 20s in all conditions.

[0043] (Study of an approximate brightness calculation formula for spaces facing windows) When the window surface is highly luminous, the threshold value based on the average luminance of the window surface is set to 50 cd / m 2 " and the coefficient of determination of the prediction formula for each case was confirmed. As shown in Figure 12(a), the threshold value of the average window luminance with the highest coefficient of determination for each case was "1500cd / m 2 ". Furthermore, when the threshold value for the luminance ratio was changed in increments of "0.1" and the coefficient of determination for the prediction formula in each case was checked, the coefficient of determination changed at the boundary of a luminance ratio of "0.7", as shown in Figure 12(b). From the above, (1) Window surface average luminance 1500 cd / m 2 (2) Window surface average luminance 1500cd / m 2 We created a new formula for estimating the brightness of spaces divided into (1) less than 1500cd / m2 and a luminance ratio of 0.7 or more, and (2) a luminance ratio of less than 0.7. The results are shown in Figures 13 and 14. 2 Above this, the coefficient for the window surface was negative, and the coefficient of determination was 0.62. On the other hand, the window surface luminance was 1500 cd / m 2 When the brightness ratio was less than 0.7 and the luminance ratio was 0.7 or more, the p-value of the coefficient for the window surface was high at 0.382, and the brightness of the space could be explained to a certain extent by the luminance and solid angle of the ceiling surface alone.

[0044] (Study of an approximate brightness calculation formula for a space facing a wall) As for the brightness of the space when the line of sight is directed toward a wall, an analysis was conducted by using the solid angle of each target surface of the average luminance of the window and ceiling surfaces "without lighting" as explanatory variables, just as with the window orientation, and setting a threshold value similar to that of the approximate formula for the window orientation. The results are shown in Figures 15 and 16. Looking at the coefficients of each window surface luminance, there is a tendency for the window surfaces to have a negative effect on the evaluation of the brightness of the space in all cases, however, the p-value of the estimated coefficient is not small enough, and particularly when the luminance ratio is less than 0.7, it is believed that the brightness of the space can be adequately predicted using only the variables of the ceiling surface and solid angle. [Explanation of symbols]

[0045] 1. Lighting control system 2. Lighting equipment 3 Window surface brightness sensor 4. Ceiling surface brightness sensor 5. Control device 31 Sensor body 31a Housing 31b Recess 31c Light receiving part 32 Attachment 41 Sensor body 41a Housing 41b Recess 42 Cover

Claims

1. An indoor lighting control system, comprising: A lighting fixture installed in the room; a window surface luminance sensor that detects the luminance of a window surface or an amount of light correlated to the luminance as a first detection value; a ceiling surface luminance sensor that detects the luminance of the ceiling surface or an amount of light correlated to the luminance as a second detection value; a control device that calculates a current brightness of the indoor space from the first detection value and the second detection value using a mathematical formula having a brightness evaluation of the indoor space as a response variable, and controls the lighting device based on the calculated current brightness, The formula has explanatory variables being the luminance of the window surface, the luminance of the ceiling surface, and the solid angles of the window surface and the ceiling surface, and the formula includes a window surface-oriented formula including a coefficient that takes into account the brightness felt by an occupant facing the window surface, and a wall surface-oriented formula including a coefficient that takes into account the brightness felt by an occupant facing the wall surface, The control device evaluates the current brightness of the indoor space by using either the window surface orientation formula or the wall surface orientation formula according to the indoor situation. A lighting control system comprising:

2. 2. The lighting control system of claim 1, wherein the formula is: [0010]

3. 3. The lighting control system according to claim 1, wherein the window surface orientation formula and the wall surface orientation formula are classified based on the following three conditions, so that there are a total of six formulas with different coefficients. (1) When the window surface luminance is equal to or greater than the reference window surface luminance (2) When the window surface luminance is smaller than the reference window surface luminance and the ratio of the window surface luminance to the ceiling surface luminance is equal to or greater than the reference luminance ratio. (3) When the window surface luminance is smaller than the reference window surface luminance and the ratio of the window surface luminance to the ceiling surface luminance is smaller than the reference luminance ratio

4. The room is divided into a plurality of areas for controlling dimming, The control device calculates the brightness in a plurality of directions at the representative point of each divided area for each direction using either the window surface orientation formula or the wall surface orientation formula, and controls the dimming of the area based on the brightness evaluation in the direction with the lowest brightness.

4. A lighting control system according to claim 1, wherein the lighting control system comprises:

5. The window surface luminance sensor and the ceiling surface luminance sensor are installed on a ceiling.

5. A lighting control system according to claim 1, wherein the lighting control system comprises:

6. The window surface luminance sensor includes a first illuminance sensor element that detects illuminance in a floor surface direction, a housing that accommodates the first illuminance sensor element, and an attachment that is attached to the housing; the attachment has a light reflecting portion that guides light coming from the direction of the window surface to the first illuminance sensor element, The control device has information indicating a relationship between the amount of light detected by the window surface luminance sensor and the luminance of the window surface, and calculates the luminance of the window surface based on the information.

6. A lighting control system as claimed in claim 5.

7. the ceiling surface luminance sensor includes a second illuminance sensor element for detecting illuminance in a floor surface direction, a housing for accommodating the second illuminance sensor element, and a translucent cover attached to the housing; The light transmitted through the cover is guided to the second illuminance sensor element, The control device has information indicating a relationship between the amount of light detected by the ceiling surface luminance sensor and the luminance of the ceiling surface, and calculates the luminance of the ceiling surface based on the information.

7. A lighting control system according to claim 5 or 6.

8. A method for controlling lighting in a room, comprising: A lighting fixture, a window surface luminance sensor that detects a luminance of a window surface or an amount of light correlated with the luminance as a first detection value, and a ceiling surface luminance sensor that detects a luminance of a ceiling surface or an amount of light correlated with the luminance as a second detection value are installed in the room; a detection step of detecting the first detection value and the second detection value using the window surface luminance sensor and the ceiling surface luminance sensor; a control step of calculating a current brightness of the indoor space from the first detection value and the second detection value using a mathematical formula having a brightness evaluation of the indoor space as a response variable, and controlling the lighting device based on the calculated current brightness, The formula has explanatory variables being the luminance of the window surface, the luminance of the ceiling surface, and the solid angles of the window surface and the ceiling surface, and the formula includes a window surface-oriented formula including a coefficient that takes into account the brightness felt by an occupant facing the window surface, and a wall surface-oriented formula including a coefficient that takes into account the brightness felt by an occupant facing the wall surface, In the control step, the window surface orientation formula or the wall surface orientation formula is used according to the indoor situation to evaluate the current brightness of the indoor space. A lighting control method comprising:

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