Illumination system and illumination method

Abstract

To provide an illumination system capable of adjusting the chromaticity of output light and capable of achieving output light that has a high general color rendering index Ra, and an illumination method.SOLUTION: A control unit included in the illumination system achieves output light that has the chromaticity values in the first region of a triangle whose vertices are the three closest points to the blackbody locus among the four points by emitting from 3 out of the 4 light sources corresponding to the 3 vertices of the first region and achieves output light that has chromaticity values in the second triangular area excluding the first area from the rectangular area by emitting 3 of the 4 light sources corresponding to the 3 vertices of the second region.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Conventionally, various techniques have been proposed for adjusting the color tone of output light from a lighting device (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-123429 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention provides a lighting system and a lighting method capable of adjusting the chromaticity of output light, which can realize output light having a high general color rendering index Ra. [Means for solving the problem]

[0005] According to one embodiment of the present invention, there is provided a lighting system comprising a control unit which controls four light sources which emit light having different chromaticity values ​​from each other, wherein a rectangular region on a chromaticity coordinate system having four vertices corresponding to the chromaticity values ​​of the light emitted by the four light sources includes at least a portion of the chromaticity range of the light source color defined in JIS Z9112, and the control unit realizes output light having chromaticity values ​​within a first triangular region having vertices that are the top three points among the four points which are closest to the blackbody locus, by causing three of the four light sources which correspond to the three vertices of the first region to emit light, and realizes output light having chromaticity values ​​within a second triangular region which is the rectangular region excluding the first region, by causing three of the four light sources which correspond to the three vertices of the second region to emit light.

[0006] An illumination method according to one aspect of the present invention includes a control step of controlling four light sources that emit light having different chromaticity values ​​from each other, wherein a rectangular region on a chromaticity coordinate system having four vertices corresponding to the chromaticity values ​​of the light emitted by the four light sources includes at least a portion of the chromaticity range of the light source color defined in JIS Z9112, and in the control step, output light having chromaticity values ​​within a first triangular region having vertices that are top three points among the four points that are closest to the blackbody locus is realized by causing three of the four light sources that correspond to the three vertices of the first region to emit light, and output light having chromaticity values ​​within a second triangular region obtained by excluding the first region from the rectangular region is realized by causing three of the four light sources that correspond to the three vertices of the second region to emit light.

[0007] A program according to one aspect of the present invention is a program for causing a computer to execute the lighting method. Effect of the Invention

[0008] According to the present invention, there is provided a lighting system and a lighting method capable of adjusting the chromaticity of output light, which can realize output light having a high general color rendering index Ra. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram showing a functional configuration of a lighting system according to the first embodiment. [Diagram 2] FIG. 2 is a diagram showing chromaticity coordinates in which chromaticity values ​​of four light sources included in the lighting system according to the first embodiment are plotted. [Diagram 3] FIG. 3 is a diagram showing the general color rendering index Ra of output light obtained by the chromaticity control method (control example 1) in the lighting system according to the first embodiment. [Figure 4] FIG. 4 is a diagram showing chromaticity coordinates in which points relating to control example 2 of the lighting system according to embodiment 1 are plotted. [Diagram 5]FIG. 5 is a diagram showing a simulation result of the luminous flux and general color rendering index Ra of the output light realized by Control Example 2 of the first embodiment. [Figure 6] FIG. 6 is a block diagram showing a functional configuration of a lighting system according to the second embodiment. [Figure 7] FIG. 7 is a diagram showing chromaticity coordinates in which the chromaticity values ​​of the four light sources included in the lighting system according to the second embodiment are plotted. [Figure 8] FIG. 8 is a diagram showing the general color rendering index Ra of output light obtained by the chromaticity control method (control example 1) in the lighting system according to the second embodiment. [Figure 9] FIG. 9 is a diagram showing chromaticity coordinates on which points relating to control example 2 of the lighting system according to embodiment 2 are plotted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments will be described in detail with reference to the drawings. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component arrangement and connection forms, steps, and order of steps shown in the following embodiments are merely examples and are not intended to limit the present invention. In addition, among the components in the following embodiments, components that are not described in the independent claims will be described as optional components.

[0011] In addition, each drawing is a schematic diagram and is not necessarily a precise illustration. In addition, in each drawing, the same reference numerals are used for substantially the same configuration, and duplicated explanations may be omitted or simplified.

[0012] (Embodiment 1) [composition] First, a description will be given of the configuration of a lighting system according to embodiment 1. Fig. 1 is a block diagram showing the functional configuration of the lighting system according to embodiment 1.

[0013] The lighting system 10 is a system that can cause the lighting device 40 to emit light with a chromaticity desired by a user by independently adjusting the dimming of a blue light source 42b, a green light source 42g, a red light source 42r, and a blue-green light source 42bg included in a light source unit 42 of the lighting device 40. In other words, the lighting system 10 is a system that supports a chromaticity adjustment function of the lighting device 40. The lighting system 10 includes an input device 20, a control device 30, and a lighting device 40. Note that the lighting system 10 may include a plurality of lighting devices 40 for one control device 30.

[0014] The input device 20 receives an input for specifying chromaticity from a user. The input device 20 is, for example, a portable information terminal such as a smartphone or a tablet terminal, but may also be a stationary information terminal that is fixedly installed on a wall or the like. The input device 20 may be realized by installing an application program corresponding to the lighting system 10 in a general-purpose device, or may be a device dedicated to the lighting system 10.

[0015] The control device 30 controls the lighting device 40 to emit light with the chromaticity input to the input device 20. The control device 30 includes a control unit 31 and a storage unit 32. The input device 20 and the control device 30 may be realized as a single integrated device.

[0016] The control unit 31 controls the light emission of the lighting device 40. Specifically, the control unit 31 can adjust the chromaticity of the light emitted by the lighting device 40 by transmitting a control signal to the lighting device 40. The control unit 31 transmits the control signal to the lighting device 40 by, for example, wireless communication, but may transmit the control signal to the lighting device 40 by wired communication. The control unit 31 is realized by, for example, a microcomputer, but may also be realized by a processor. The function of the control unit 31 is realized by the microcomputer or processor constituting the control unit 31 executing a computer program stored in the storage unit 32.

[0017] The storage unit 32 is a storage device that stores the computer program executed by the control unit 31 and various information necessary for controlling the lighting device 40. Specifically, the storage unit 32 is realized by a semiconductor memory or the like.

[0018] The lighting device 40 is installed, for example, indoors and illuminates the indoor space. The lighting device 40 is, for example, a ceiling light, but may be other lighting devices such as a spotlight or a downlight. The lighting device 40 includes a dimming circuit 41 and a light source unit 42. The light source unit 42 includes a red light source 42r, a green light source 42g, a blue light source 42b, and a blue-green light source 42bg.

[0019] The dimming circuit 41 is a circuit that supplies power to the light source unit 42 in response to a control signal transmitted from the control device 30 (control unit 31). The dimming circuit 41 includes, for example, a chopper control circuit. The control unit 31 changes the current supplied to the light source unit 42 by switching a switching element included in the dimming circuit 41 (chopper control circuit) using a control signal. The dimming circuit 41 can supply power (current) independently to each of the blue light source 42b, the green light source 42g, the red light source 42r, and the blue-green light source 42bg of the light source unit 42. That is, the dimming circuit 41 can independently dim the red light source 42r, the green light source 42g, the blue light source 42b, and the blue-green light source 42bg of the light source unit 42.

[0020] The blue light source 42b is a light source that emits blue light. The blue light source 42b emits blue light (specifically, including blue and purple light) with an emission peak wavelength of, for example, 380 nm or more and 480 nm or less. Specifically, the blue light source 42b is a light-emitting module using a blue LED, but the specific form of the blue light source 42b is not particularly limited.

[0021] The green light source 42g is a light source that emits green light. The green light source 42g emits, for example, green light with an emission peak wavelength of 480 nm or more and 580 nm or less (specifically, including green-blue, blue-green, green, and yellow-green light). Specifically, the green light source 42g is a light-emitting module using a green LED, but the specific form of the green light source 42g is not particularly limited.

[0022] The red light source 42r is a light source that emits red light. The red light source 42r emits red light with an emission peak wavelength of, for example, 600 nm or more and 680 nm or less. Specifically, the red light source 42r is a light-emitting module using a red LED, but the specific form of the red light source 42r is not particularly limited.

[0023] The blue-green light source 42bg is a light source that emits blue-green light (blue-green may also be expressed as royal blue, etc.) and is an example of another light source or another blue light source. The blue-green light source 42bg emits blue-green light (blue light with a longer wavelength than the blue light source 42b) with an emission peak wavelength of, for example, 465 nm or more and 490 nm or less. The blue-green light source 42bg is specifically a light-emitting module that uses an LED that emits blue-green light, but the specific embodiment of the blue-green light source 42bg is not particularly limited.

[0024] [Chromaticity control example 1] The lighting system 10 can improve the color rendering of the output light by selectively emitting the blue light source 42b, the green light source 42g, the red light source 42r, and the blue-green light source 42bg when controlling the chromaticity of the output light of the lighting device 40. The output light is a light obtained by combining at least one of the light emitted by the red light source 42r, the light emitted by the green light source 42g, the light emitted by the blue light source 42b, and the light emitted by the blue-green light source 42bg, and means the light finally emitted from the lighting device 40. Hereinafter, a first example of controlling the chromaticity of the lighting system 10 will be described with reference to a chromaticity diagram (chromaticity coordinates). FIG. 2 is a diagram showing chromaticity coordinates in which the chromaticity values ​​of the red light source 42r, the green light source 42g, the blue light source 42b, and the blue-green light source 42bg are plotted. The chromaticity coordinates in FIG. 2 show a color space defined in CIE1931.

[0025] The chromaticity coordinates in Figure 2 show point B1 indicating the chromaticity value of the blue light emitted by blue light source 42b, point G indicating the chromaticity value of the green light emitted by green light source 42g, point R indicating the chromaticity value of the red light emitted by red light source 42r, and point B2 indicating a fourth chromaticity value of the blue-green light emitted by blue-green light source 42bg.

[0026] On the chromaticity coordinate system, a rectangular region with vertices B1, G, R, and B2 includes at least a part of the chromaticity range of the light source color defined in JIS Z 9112. Here, the light source color refers to five types of light source colors: daylight color (D), natural white (N), white (W), warm white (WW), and light bulb color (L), and the chromaticity ranges of the five types of light source colors are five approximately parallelogram regions near the blackbody locus in Fig. 2. Specifically, the rectangular region with vertices B1, G, R, and B2 includes the entire chromaticity ranges of daylight color (D), natural white (N), white (W), and warm white (WW), and a part of the chromaticity range of light bulb color (L). The lighting system 10 can realize output light having chromaticity values ​​within a rectangular area with vertices at points B1, G, R, and B2, and it can be said that the chromaticity range of the output light that the lighting system 10 can realize is relatively wide.

[0027] The lighting system 10 divides the rectangular region into a first triangular region having vertices G, R, and B2, and a second triangular region having vertices B1, R, and B2, and adjusts the chromaticity, thereby improving the color rendering of the output light. There are two ways to divide the rectangular region into two triangular regions. In the lighting system 10, the triangular region having vertices of the top three points among the four points B1, G, R, and B2 that are closest to the blackbody locus is set as the first region, and the triangular region obtained by removing the first region from the rectangular region is set as the second region. The distance from the point B1 to the blackbody locus means, for example, the average value of the distances from the point B1 to each of the multiple points when the blackbody locus is regarded as a set of multiple points. The same applies to the distances from the points G, R, and B2 to the blackbody locus.

[0028] For example, when a point indicating a chromaticity value desired by the user input to the input device 20 is located within the first region, the control unit 31 of the control device 30 does not emit light from the blue light source 42b, but emits light from the three light sources, the green light source 42g, the red light source 42r, and the blue-green light source 42bg, and adjusts the light intensity independently, thereby realizing output light having a chromaticity value desired by the user. Similarly, when a point indicating a chromaticity value desired by the input device 20 is located within the second region, the control unit 31 of the control device 30 does not emit light from the green light source 42g, but emits light from the three light sources, the blue light source 42b, the red light source 42r, and the blue-green light source 42bg, and adjusts the light intensity independently, thereby realizing output light having a chromaticity value desired by the user.

[0029] The average color rendering index Ra of the output light obtained by such a chromaticity control method will be described below while comparing it with the average color rendering index Ra of the output light obtained by a chromaticity control method according to a comparative example. Fig. 3 is a diagram showing the average color rendering index Ra of the output light obtained by the chromaticity control method in the lighting system 10 (hereinafter also simply referred to as control example 1).

[0030] In FIG. 3, the average color rendering index Ra of the output light obtained by the chromaticity control method according to the comparative example is also shown. The chromaticity control method according to the comparative example is a control method in which the output light having the chromaticity values ​​located within points B1, G, and R is realized by emitting the three light sources of blue light source 42b, green light source 42g, and red light source 42r without emitting the blue-green light source 42bg, and by independently dimming the light sources. That is, the comparative example is different from control example 1 in the way in which the rectangle is divided into two triangular regions. In FIG. 3, the output light is white light with Duv=0. In FIG. 3, the horizontal axis indicates the color temperature (Tc) of the output light, and the vertical axis indicates the average color rendering index Ra of the output light.

[0031] As shown in FIG. 3, according to Control Example 1, it is possible to realize output light having a higher general color rendering index Ra than the comparative example.

[0032] As described above, in the lighting system 10, the control unit 31 realizes output light having chromaticity values ​​in a first region having vertices G, R, and B2 by causing three light sources corresponding to the points G, R, and B2 to emit light, and realizes output light having chromaticity values ​​in a triangular second region having vertices B1, R, and B2 by causing three light sources corresponding to the points B1, R, and B2 to emit light. The first region is specifically a triangular region having vertices that are the top three points among the points B1, G, R, and B2 that are closest to the blackbody locus, and the second region is a triangular region obtained by excluding the first region from a quadrangular region having vertices B1, G, R, and B2. This allows the lighting system 10 to realize output light having a high general color rendering index Ra. The lighting system 10 can improve the general color rendering index Ra of output light having a light source color (any of five types) defined in JIS Z9112, for example, and reduce color unevenness on the surface illuminated by the light.

[0033] [Control example 2] Control example 2 of the chromaticity of the lighting system 10 will be described with reference to a chromaticity diagram (chromaticity coordinates). Fig. 4 is a diagram showing chromaticity coordinates in which points related to control example 2 are plotted. The chromaticity coordinates in Fig. 4 indicate a color space defined in CIE1931. The chromaticity coordinates in Fig. 4 are basically the same as those in Fig. 2, except that a first point P1, a second point P2, a third point P3, a fourth point P4, and a fifth point P5 are illustrated.

[0034] The first point P1 is a point located on a line segment connecting point B2 indicating the chromaticity value of blue-green light source 42bg and point G indicating the chromaticity value (an example of the first chromaticity value) of green light source 42g. The first point P1 is a point indicating the chromaticity value when each of blue-green light source 42bg and green light source 42g is caused to emit light at maximum brightness.

[0035] The second point P2 is located on the line segment connecting point B2 indicating the chromaticity value of the blue-green light source 42bg and point R indicating the chromaticity value (an example of the second chromaticity value) of the red light source 42r. The second point P2 is a point indicating the chromaticity value when each of the blue-green light source 42bg and the red light source 42r is caused to emit light at maximum brightness.

[0036] The third point P3 is a point located within the first region and indicates the chromaticity value when each of the three light sources (green light source 42g, red light source 42r, and blue-green light source 42bg) corresponding to the three vertices of the first region emits light at maximum brightness.

[0037] The fourth point P4 is located on the line segment connecting the point B2 indicating the chromaticity value of the blue-green light source 42bg and the point B1 indicating the chromaticity value (an example of the third chromaticity value) of the blue light source 42b. The fourth point P4 is a point indicating the chromaticity value when each of the blue-green light source 42bg and the blue light source 42b is caused to emit light at maximum brightness.

[0038] The fifth point P5 is a point located within the second region and indicates the chromaticity value when each of the three light sources (blue light source 42b, red light source 42r, and blue-green light source 42bg) corresponding to the three vertices of the second region emits light at maximum brightness.

[0039] In the above-described control example 1, the chromaticity values ​​in the first region of the triangle with vertices G, R, and B2 are realized by emitting light from the green light source 42g, the red light source 42r, and the blue-green light source 42bg. Here, the chromaticity values ​​in the first target region (the hatched region in FIG. 4) in the first region can be realized by emitting light from all of the blue light source 42b, the green light source 42g, the red light source 42r, and the blue-green light source 42bg, and this makes it possible to improve both the general color rendering index Ra of the output light and the amount of light of the output light.

[0040] Therefore, in control example 2, controller 31 realizes the chromaticity values ​​within the first target region by causing all of blue light source 42b, green light source 42g, red light source 42r, and blue-green light source 42bg to emit light and independently adjust the light intensity. Note that the first target region is an overlapping region of a square surrounded by point B2 indicating the chromaticity value of blue-green light source 42bg, a first point P1, a second point P2, and a third point P3, and a triangular region surrounded by point G (point indicating the first chromaticity value), point R (point indicating the second chromaticity value), and point B1 (point indicating the third chromaticity value).

[0041] The control unit 31 realizes, for example, output light having a certain chromaticity value in the first target region as follows. The control unit 31 calculates a first dimming value of each light source when the chromaticity value in the first target region is realized by making the green light source 42g, the red light source 42r, and the blue-green light source 42bg emit light without making the blue-green light source 42b emit light. The control unit 31 calculates a second dimming value of each light source when the chromaticity value in the first target region is realized by making the blue light source 42b, the green light source 42g, and the red light source 42r emit light without making the blue-green light source 42bg emit light. The control unit 31 sets the dimming value obtained by adding up the first dimming value and the second dimming value as the final dimming value. FIG. 5 is a diagram showing a simulation result of the luminous flux and the general color rendering index Ra of the output light realized by the control example 2.

[0042] 5, when output light having chromaticity values ​​of x=0.263, y=0.284 in the first target region is realized by control example 1, the total luminous flux is 125 and the average color rendering index Ra is 91. Note that realizing the output light by control example 1 corresponds to causing the green light source 42g, the red light source 42r, and the blue-green light source 42bg to emit light at the first dimming value in the above description.

[0043] 5, the "additional amount" in the "first target area" column means a case where it is assumed that the output light is realized by making the blue light source 42b, the green light source 42g, and the red light source 42r emit light at the second dimming value described above. In this case, the total luminous flux is 72, and the general color rendering index Ra is 84.

[0044] 5, when output light having chromaticity values ​​of x=0.263, y=0.284 in the first target region is realized by control example 2, the total luminous flux is 197 and the average color rendering index Ra is 93. Note that realizing output light by control example 2 corresponds to causing blue light source 42b, green light source 42g, red light source 42r, and blue-green light source 42bg to emit light at a final dimming value which is the sum of the first dimming value and the second dimming value described above.

[0045] In this way, according to control example 2, it is possible to improve the general color rendering index Ra and increase the amount of light of the output light having the above chromaticity values ​​in the first target region. In control example 2, when the output light having the above chromaticity values ​​in the first target region is emitted from the lighting device 40, the blue-green light source 42bg emits light at maximum output (maximum brightness).

[0046] In the above-described control example 1, the chromaticity values ​​in the second region of the triangle with vertices B1, R, and B2 are realized by emitting light from the blue light source 42b, the red light source 42r, and the blue-green light source 42bg. Here, the chromaticity values ​​in the second target region (the hatched region in FIG. 4) in the second region can be realized by emitting light from all of the blue light source 42b, the green light source 42g, the red light source 42r, and the blue-green light source 42bg, and this makes it possible to improve both the general color rendering index Ra of the output light and the amount of light of the output light.

[0047] Therefore, in control example 2, controller 31 realizes the chromaticity values ​​in the second target region by causing all of blue light source 42b, green light source 42g, red light source 42r, and blue-green light source 42bg to emit light and independently adjust the light intensity. Note that the second target region is an overlapping region of a square surrounded by point B2 indicating the chromaticity value of blue-green light source 42bg, second point P2, fourth point P4, and fifth point P5, and a triangular region surrounded by point G (point indicating the first chromaticity value), point R (point indicating the second chromaticity value), and point B1 (point indicating the third chromaticity value).

[0048] For example, the control unit 31 realizes output light having a certain chromaticity value in the second target region as follows. The control unit 31 calculates a third dimming value of each light source when the chromaticity value in the second target region is realized by making the blue light source 42b, the red light source 42r, and the blue-green light source 42bg emit light without making the green light source 42g emit light. The control unit 31 also calculates a fourth dimming value of each light source when the chromaticity value in the second target region is realized by making the blue light source 42b, the green light source 42g, and the red light source 42r emit light without making the blue-green light source 42bg emit light. The control unit 31 determines the dimming value obtained by adding up the third dimming value and the fourth dimming value as the final dimming value.

[0049] 5, when output light having chromaticity values ​​of x=0.254, y=0.270 in the second target region is realized by control example 1, the total luminous flux is 115 and the average color rendering index Ra is 92. Note that realizing the output light by control example 1 corresponds to causing the blue light source 42b, the red light source 42r, and the blue-green light source 42bg to emit light at the third dimming value in the above description.

[0050] 5, the "additional amount" in the "second target area" column means the case where it is assumed that the output light is realized by making the blue light source 42b, the green light source 42g, and the red light source 42r emit light at the fourth dimming value in the above description. In this case, the total luminous flux is 91, and the general color rendering index Ra is 82.

[0051] 5, when output light having chromaticity values ​​of x=0.254, y=0.270 in the second target region is realized by control example 2, the total luminous flux is 206 and the average color rendering index Ra is 92. Note that realizing output light by control example 2 corresponds to causing blue light source 42b, green light source 42g, red light source 42r, and blue-green light source 42bg to emit light at a final dimming value which is the sum of the third dimming value and the fourth dimming value described above.

[0052] In this way, according to control example 2, it is possible to improve the general color rendering index Ra and increase the amount of light of the output light having the above chromaticity values ​​in the second target region. In control example 2, when the output light having the above chromaticity values ​​in the second target region is emitted from the lighting device 40, the blue-green light source 42bg emits light at maximum output (maximum brightness).

[0053] In addition, in the first target region and the second target region, it may be possible to switch between applying control example 1 and applying control example 2. For example, the control unit 31 may selectively execute an operation of a color rendering priority mode that prioritizes the color rendering of output light having chromaticity values ​​belonging to the first target region and the second target region, and an operation of a light intensity priority mode that prioritizes the light intensity of output light having chromaticity values ​​belonging to the first target region and the second target region. In the operation of the color rendering priority mode, as described in the control example 1, the control unit 31 realizes the chromaticity values ​​belonging to the first target region by causing three light sources corresponding to the three vertices of the first region to emit light, and realizes the chromaticity values ​​belonging to the second target region by causing three light sources corresponding to the three vertices of the second region to emit light. In the operation of the light intensity priority mode, as described in the control example 2, the control unit 31 realizes the chromaticity values ​​belonging to the first target region and the second target region by causing four light sources provided in the lighting system 10 to emit light. The color rendering priority mode is an example of a first mode, and the light intensity priority mode is an example of a second mode. Such switching of the operation mode is performed based on, for example, a user's input to the input device 20.

[0054] (Embodiment 2) [composition] First, a description will be given of the configuration of a lighting system according to embodiment 2. Fig. 6 is a block diagram showing the functional configuration of the lighting system according to embodiment 2.

[0055] The lighting system 10a according to the second embodiment is a system that can cause the lighting device 40a to emit light with a chromaticity desired by a user by independently adjusting the dimming of a blue light source 42b, a green light source 42g, a red light source 42r, and a yellow light source 42y included in a light source unit 42a of the lighting device 40a. In other words, the lighting system 10a is a system that supports a chromaticity adjustment function of the lighting device 40a. The lighting system 10a includes an input device 20, a control device 30, and a lighting device 40a. Note that the lighting system 10a may include a plurality of lighting devices 40a for one control device 30.

[0056] Since the input device 20 and the control device 30 have already been described, detailed description thereof will be omitted.

[0057] The illumination device 40a has a configuration similar to that of the illumination device 40, but differs in that it includes a yellow light source 42y instead of the blue-green light source 42bg.

[0058] The yellow light source 42y is a light source that emits yellow light and is an example of another light source. For example, the yellow light source 42y emits yellow light with an emission peak wavelength of 550 nm or more and 590 nm or less. Specifically, the yellow light source 42y is a light-emitting module using an LED that emits yellow light, but the specific embodiment of the yellow light source 42y is not particularly limited.

[0059] The basic configurations of blue light source 42b, green light source 42g, and red light source 42r included in lighting device 40a are similar to those of blue light source 42b, green light source 42g, and red light source 42r included in lighting device 40, but their chromaticity values ​​are slightly different.

[0060] [Chromaticity control example 1] The lighting system 10a can improve the color rendering of the output light by selectively emitting light from the blue light source 42b, the green light source 42g, the red light source 42r, and the yellow light source 42y when controlling the chromaticity of the output light of the lighting device 40a. The output light is a light obtained by combining at least one of the light emitted by the red light source 42r, the light emitted by the green light source 42g, the light emitted by the blue light source 42b, and the light emitted by the yellow light source 42y, and means the light finally emitted from the lighting device 40a. Hereinafter, a first example of controlling the chromaticity of the lighting system 10a will be described with reference to a chromaticity diagram (chromaticity coordinates). FIG. 7 is a diagram showing chromaticity coordinates in which the chromaticity values ​​of the red light source 42r, the green light source 42g, the blue light source 42b, and the yellow light source 42y are plotted. The chromaticity coordinates in FIG. 7 show a color space defined in CIE1931.

[0061] The chromaticity coordinates in Figure 7 show point B indicating the chromaticity value of the blue light emitted by blue light source 42b, point G indicating the chromaticity value of the green light emitted by green light source 42g, point R indicating the chromaticity value of the red light emitted by red light source 42r, and point Y indicating the fourth chromaticity value of the blue-green light emitted by yellow light source 42y.

[0062] On the chromaticity coordinate system, a rectangular region with vertices B, G, R, and Y includes the chromaticity range of the light source color defined in JIS Z9112. Here, the light source color refers to five types of light source colors: daylight color (D), natural white (N), white (W), warm white (WW), and incandescent light (L), and the chromaticity range of the five types of light source colors is five approximately parallelogram regions near the blackbody locus in Fig. 7. The lighting system 10a can realize output light having chromaticity values ​​within the rectangular region with vertices B, G, R, and Y, and it can be said that the chromaticity range of the output light that the lighting system 10a can realize is relatively wide.

[0063] The lighting system 10a divides the rectangular region into a first triangular region having vertices B, R, and Y, and a second triangular region having vertices B, G, and Y, and adjusts the chromaticity, thereby improving the color rendering of the output light. There are two possible ways to divide the rectangular region into two triangular regions. In the lighting system 10a, the triangular region having vertices of the top three points among the four points B, G, R, and Y that are closest to the blackbody locus is set as the first region, and the triangular region obtained by removing the first region from the rectangular region is set as the second region. The distance from the point B to the blackbody locus means, for example, the average value of the distances from the point B to each of the multiple points when the blackbody locus is regarded as a set of multiple points. The same applies to the distances from the points G, R, and Y to the blackbody locus.

[0064] For example, when a point indicating a chromaticity value desired by the user input to the input device 20 is located within the first region, the control unit 31 of the control device 30 realizes output light having a chromaticity value desired by the user by turning on the three light sources, blue light source 42b, red light source 42r, and yellow light source 42y, without turning on the green light source 42g, and independently adjusting the brightness of the light sources. Similarly, when a point indicating a chromaticity value desired by the user input to the input device 20 is located within the second region, the control unit 31 of the control device 30 realizes output light having a chromaticity value desired by the user by turning on the three light sources, blue light source 42b, green light source 42g, and yellow light source 42y, without turning on the red light source 42r, and independently adjusting the brightness of the light sources.

[0065] The average color rendering index Ra of the output light obtained by such a chromaticity control method will be described below while comparing it with the average color rendering index Ra of the output light obtained by a chromaticity control method according to a comparative example. Fig. 8 is a diagram showing the average color rendering index Ra of the output light obtained by the chromaticity control method in the lighting system 10a (hereinafter also simply referred to as control example 1).

[0066] In FIG. 8, the average color rendering index Ra of the output light obtained by the chromaticity control method according to the comparative example is also shown. The chromaticity control method according to the comparative example is a control method in which the output light having the chromaticity values ​​located within points B, G, and R is realized by emitting light from three light sources, namely, blue light source 42b, green light source 42g, and red light source 42r, without emitting light from yellow light source 42y, and independently dimming the light. That is, the comparative example is different from control example 1 in the way in which the rectangle is divided into two triangular regions. In FIG. 8, the output light is white light with Duv=0. In FIG. 8, the horizontal axis indicates the color temperature (Tc) of the output light, and the vertical axis indicates the average color rendering index Ra of the output light.

[0067] As shown in FIG. 8, according to Control Example 1, it is possible to realize output light having a higher general color rendering index Ra than the comparative example.

[0068] As described above, in the lighting system 10a, the control unit 31 realizes output light having chromaticity values ​​in a first region having vertices at points B, R, and Y by causing three light sources corresponding to points B, R, and Y to emit light, and realizes output light having chromaticity values ​​in a triangular second region having vertices at points B, G, and Y by causing three light sources corresponding to points B, G, and Y to emit light. The first region is specifically a triangular region having vertices at the top three points among points B, G, R, and Y that are closest to the blackbody locus, and the second region is a triangular region obtained by excluding the first region from a quadrangular region having vertices at points B, G, R, and Y. This allows the lighting system 10a to realize output light having a high general color rendering index Ra. The lighting system 10a can improve the general color rendering index Ra of output light having a light source color (any of five types) defined in JIS Z9112, for example, and reduce color unevenness on the surface illuminated by the light.

[0069] [Control example 2] Control example 2 of the chromaticity of the lighting system 10a will be described with reference to a chromaticity diagram (chromaticity coordinates). Fig. 9 is a diagram showing chromaticity coordinates in which points related to control example 2 are plotted. The chromaticity coordinates in Fig. 9 indicate a color space defined in CIE1931. The chromaticity coordinates in Fig. 9 are basically the same as those in Fig. 7, except that a first point P1, a second point P2, a third point P3, a fourth point P4, and a fifth point P5 are illustrated.

[0070] The first point P1 is a point located on a line segment connecting a point Y indicating the chromaticity value of the yellow light source 42y and a point R indicating the chromaticity value (another example of the first chromaticity value) of the red light source 42r. The first point P1 is a point indicating the chromaticity value when each of the yellow light source 42y and the red light source 42r is caused to emit light with maximum brightness.

[0071] The second point P2 is located on the line segment connecting point Y indicating the chromaticity value of yellow light source 42y and point B indicating the chromaticity value (another example of the second chromaticity value) of blue light source 42b. The second point P2 is a point indicating the chromaticity value when each of yellow light source 42y and blue light source 42b is caused to emit light at maximum brightness.

[0072] The third point P3 is a point located within the first region and indicates the chromaticity value when each of the three light sources (blue light source 42b, red light source 42r, and yellow light source 42y) corresponding to the three vertices of the first region emits light at maximum brightness.

[0073] The fourth point P4 is located on the line segment connecting point Y indicating the chromaticity value of yellow light source 42y and point G indicating the chromaticity value (another example of the third chromaticity value) of green light source 42g. The fourth point P4 is a point indicating the chromaticity value when each of yellow light source 42y and green light source 42g is caused to emit light with maximum brightness.

[0074] The fifth point P5 is a point located within the second region and indicates the chromaticity value when each of the three light sources (blue light source 42b, green light source 42g, and yellow light source 42y) corresponding to the three vertices of the second region emits light at maximum brightness.

[0075] In the above-described control example 1, the chromaticity values ​​in the first region of the triangle with vertices B, R, and Y are realized by emitting light from the blue light source 42b, the red light source 42r, and the yellow light source 42y. Here, the chromaticity values ​​in the first target region (the hatched region in FIG. 9) in the first region can be realized by emitting light from all of the blue light source 42b, the green light source 42g, the red light source 42r, and the yellow light source 42y, and this makes it possible to simultaneously improve the general color rendering index Ra of the output light and increase the amount of light of the output light.

[0076] Therefore, in control example 2, controller 31 realizes the chromaticity values ​​in the first target region by causing all of blue light source 42b, green light source 42g, red light source 42r, and yellow light source 42y to emit light and independently adjust the light intensity. Note that the first target region is an overlapping region of a square region surrounded by point Y indicating the chromaticity value of yellow light source 42y, first point P1, second point P2, and third point P3, and a triangular region surrounded by point R (point indicating the first chromaticity value), point B (point indicating the second chromaticity value), and point G (point indicating the third chromaticity value).

[0077] The control unit 31 realizes output light having a certain chromaticity value in the first target region, for example, as follows. The control unit 31 calculates a fifth dimming value of each light source when the chromaticity value in the first target region is realized by making the blue light source 42b, the red light source 42r, and the yellow light source 42y emit light without making the green light source 42g emit light. The control unit 31 also calculates a sixth dimming value of each light source when the chromaticity value in the first target region is realized by making the blue light source 42b, the green light source 42g, and the red light source 42r emit light without making the yellow light source 42y emit light. The control unit 31 sets the dimming value obtained by summing the fifth and sixth dimming values ​​as the final dimming value, thereby achieving both an improvement in the general color rendering index Ra and an increase in the amount of light of the output light having the chromaticity value in the first target region. In the control example 2, when the output light having the chromaticity value in the first target region is emitted from the lighting device 40a, the yellow light source 42y emits light at the maximum output (maximum brightness).

[0078] In the above-described control example 1, the chromaticity values ​​in the second region of the triangle with vertices B, G, and Y are realized by emitting light from the blue light source 42b, the green light source 42g, and the yellow light source 42y. Here, the chromaticity values ​​in the second target region (the hatched region in FIG. 9) in the second region can be realized by emitting light from all of the blue light source 42b, the green light source 42g, the red light source 42r, and the yellow light source 42y, and this makes it possible to improve both the general color rendering index Ra of the output light and the amount of light of the output light.

[0079] Therefore, in control example 2, controller 31 realizes the chromaticity values ​​in the second target region by causing all of blue light source 42b, green light source 42g, red light source 42r, and yellow light source 42y to emit light and independently adjust the light intensity. Note that the second target region is an overlapping region of a square region surrounded by point Y indicating the chromaticity value of yellow light source 42y, second point P2, fourth point P4, and fifth point P5, and a triangular region surrounded by point R (point indicating the first chromaticity value), point B (point indicating the second chromaticity value), and point G (point indicating the third chromaticity value).

[0080] The control unit 31 realizes, for example, output light having a certain chromaticity value in the second target region as follows. The control unit 31 calculates a seventh dimming value of each light source when the chromaticity value in the second target region is realized by making the blue light source 42b, the green light source 42g, and the yellow light source 42y emit light without making the red light source 42r emit light. The control unit 31 also calculates an eighth dimming value of each light source when the chromaticity value in the second target region is realized by making the blue light source 42b, the green light source 42g, and the red light source 42r emit light without making the yellow light source 42y emit light. The control unit 31 sets the dimming value obtained by summing the seventh dimming value and the eighth dimming value as the final dimming value, thereby improving the general color rendering index Ra of the output light having the chromaticity value in the second target region and increasing the amount of light. In the control example 2, when the output light having the chromaticity value in the second target region is emitted from the lighting device 40a, the yellow light source 42y emits light at the maximum output (maximum brightness).

[0081] In addition, in the first target region and the second target region, it may be possible to switch between applying control example 1 and applying control example 2. For example, the control unit 31 may selectively execute an operation of a color rendering priority mode that prioritizes the color rendering of output light having chromaticity values ​​belonging to the first target region and the second target region, and an operation of a light intensity priority mode that prioritizes the light intensity of output light having chromaticity values ​​belonging to the first target region and the second target region. In the operation of the color rendering priority mode, as described in the control example 1, the control unit 31 realizes the chromaticity values ​​belonging to the first target region by causing three light sources corresponding to the three vertices of the first region to emit light, and realizes the chromaticity values ​​belonging to the second target region by causing three light sources corresponding to the three vertices of the second region to emit light. In the operation of the light intensity priority mode, as described in the control example 2, the control unit 31 realizes the chromaticity values ​​belonging to the first target region and the second target region by causing four light sources provided in the lighting system 10a to emit light. The color rendering priority mode is an example of the first mode, and the light intensity priority mode is an example of the second mode. Such switching of the operation mode is performed based on, for example, a user's input to the input device 20.

[0082] (Modification) In the above-mentioned first and second embodiments, the blue light emitted by blue light source 42b, the green light emitted by green light source 42g, the red light emitted by red light source 42r, the blue-green light emitted by blue-green light source 42bg, and the yellow light emitted by yellow light source 42y are realized by light emitted from LEDs. Here, the green light emitted by green light source 42g, the red light emitted by red light source 42r, and the yellow light emitted by yellow light source 42y may be realized by fluorescence emitted by a phosphor.

[0083] In this case, each of the green light source 42g, the red light source 42r, and the yellow light source 42y includes an excitation light source realized by, for example, a blue LED, and a phosphor-containing resin that seals the excitation light source. The phosphor constituting the green light source 42g is Y3(Al,Ga)5O 12 : Ce phosphors and other yttrium aluminum garnet (YAG) green phosphors, but Lu3Al5O 12The phosphor constituting the red light source 42r may be a red phosphor such as a CaAlSiN3:Eu phosphor or a (Sr,Ca)AlSiN3:Eu phosphor. The phosphor constituting the yellow light source 42y may be a Y3(Al,Ga)5O 12 : Ce phosphors and other yttrium aluminum garnet (YAG)-based yellow phosphors, but Lu3Al5O 12 The phosphor may be a yellow phosphor of the lutetium aluminum garnet (LuAG) family, such as a :Ce phosphor.

[0084] According to control example 1 of the above-mentioned embodiments 1 and 2, even when the green light emitted by green light source 42g, the red light emitted by red light source 42r, and the yellow light emitted by yellow light source 42y are each realized by fluorescence emitted by a phosphor, it is possible to improve the average color rendering index Ra of the output light.

[0085] (Effects, etc.) As described above, the lighting system 10 or the lighting system 10a includes the control unit 31 that controls four light sources that emit light having different chromaticity values. On the chromaticity coordinates, a rectangular region having four vertices corresponding to the chromaticity values ​​of the light emitted by the four light sources includes at least a part of the chromaticity range of the light source color defined in JIS Z9112. The control unit 31 realizes output light having a chromaticity value within a first triangular region having vertices that are the top three points among the four points that are closest to the blackbody locus by making the three light sources among the four light sources that correspond to the three vertices of the first region emit light, and realizes output light having a chromaticity value within a second triangular region excluding the first region from the rectangular region by making the three light sources among the four light sources that correspond to the three vertices of the second region emit light.

[0086] Such an illumination system 10 or illumination system 10a is capable of achieving output light having a high general color rendering index Ra.

[0087] Furthermore, for example, the four light sources include a red light source 42r, a green light source 42g, a blue light source 42b, and other light sources. The points indicating the chromaticity values ​​of the other light sources are included in all of the three vertices of the first region and all of the three vertices of the second region.

[0088] Such an illumination system 10 or illumination system 10a can realize output light having a high general color rendering index Ra by controlling the red light source 42r, the green light source 42g, the blue light source 42b, and other light sources.

[0089] In addition, in the lighting system 10, the other light source is another blue light source (blue-green light source 42bg). The three vertices of the first region include a point indicating the chromaticity value of the blue-green light source 42bg, a point indicating the chromaticity value of the red light source 42r, and a point indicating the chromaticity value of the green light source 42g. The three vertices of the second region include a point indicating the chromaticity value of the blue-green light source 42bg, a point indicating the chromaticity value of the red light source 42r, and a point indicating the chromaticity value of the blue light source 42b.

[0090] Such a lighting system 10 is capable of producing output light having a high general color rendering index Ra.

[0091] In addition, in the lighting system 10a, the other light source is a yellow light source 42y. The three vertices of the first region include a point indicating the chromaticity value of the yellow light source 42y, a point indicating the chromaticity value of the blue light source 42b, and a point indicating the chromaticity value of the red light source 42r. The three vertices of the second region include a point indicating the chromaticity value of the yellow light source 42y, a point indicating the chromaticity value of the blue light source 42b, and a point indicating the chromaticity value of the green light source 42g.

[0092] Such an illumination system 10a can achieve output light having a high general color rendering index Ra.

[0093] Also, for example, the three vertices of the first region include a point indicating the chromaticity value of the other light source, a point indicating the first chromaticity value, and a point indicating the second chromaticity value. A first point P1 indicating the chromaticity value when the other light source and the light source corresponding to the point indicating the first chromaticity value are caused to emit light at maximum brightness is included on a line segment connecting the point indicating the chromaticity value of the other light source and the point indicating the first chromaticity value. A second point P2 indicating the chromaticity value when the other light source and the light source corresponding to the point indicating the second chromaticity value are caused to emit light at maximum brightness is included on a line segment connecting the point indicating the chromaticity value of the other light source and the point indicating the second chromaticity value. The first region includes a third point P3 indicating the chromaticity value when the three light sources corresponding to the three vertices of the first region are caused to emit light at maximum brightness. The three vertices of the second region include a point indicating the chromaticity value of the other light source, a point indicating the second chromaticity value, and a point indicating the third chromaticity value. A fourth point P4 indicating the chromaticity value when each of the other light source and the light source corresponding to the point indicating the third chromaticity value is caused to emit light at the maximum brightness is included on the line segment connecting the point indicating the chromaticity value of the other light source and the point indicating the third chromaticity value, and a fifth point P5 indicating the chromaticity value when each of the three light sources corresponding to the three vertices of the second region is caused to emit light at the maximum brightness is included in the second region. The control unit 31 realizes output light having a chromaticity value located in the first target region and output light having a chromaticity value located in the second target region by causing the four light sources to emit light. The first target region is a region where a region surrounded by the points indicating the chromaticity values ​​of the other light source, the first point P1, the second point P2, and the third point P3, and a region surrounded by the points indicating the first chromaticity value, the points indicating the second chromaticity value, and the points indicating the third chromaticity value overlap. The second target area is an area surrounded by points indicating the chromaticity values ​​of the other light source, the second point P2, the fourth point P4, and the fifth point P5, and an area surrounded by points indicating the first chromaticity value, points indicating the second chromaticity value, and points indicating the third chromaticity value overlap.

[0094] Such an illumination system 10 or illumination system 10a can increase the maximum amount of output light having chromaticity values ​​within the first target region and the second target region.

[0095] Also, for example, the control unit 31 selectively executes a first mode control in which output light having a chromaticity value within a first target region is realized by causing three light sources corresponding to the three vertices of the first region to emit light, and output light having a chromaticity value within a second target region is realized by causing three light sources corresponding to the three vertices of the second region to emit light, and a second mode control in which output light having a chromaticity value within the first target region and the second target region is realized by causing four light sources to emit light. The first mode is, for example, the color rendering priority mode of the above embodiment, and the second mode is, for example, the light intensity priority mode of the above embodiment.

[0096] Such a lighting system 10 or lighting system 10a can switch the method of realizing chromaticity values ​​(method of controlling chromaticity) in the first target region and the second target region.

[0097] Furthermore, a lighting method executed by a computer such as the lighting system 10 or the lighting system 10a includes a control step of controlling four light sources emitting light having different chromaticity values, and a rectangular region on a chromaticity coordinate system having four vertices corresponding to the chromaticity values ​​of the light emitted by the four light sources includes at least a part of the chromaticity range of the light source color defined in JIS Z 9112. In the control step, output light having a chromaticity value within a first triangular region having vertices that are the top three points among the four points that are closest to the blackbody locus is realized by causing three light sources among the four light sources corresponding to the three vertices of the first region to emit light, and output light having a chromaticity value within a second triangular region excluding the first region from the rectangular region is realized by causing three light sources among the four light sources corresponding to the three vertices of the second region to emit light.

[0098] Such an illumination method can achieve output light with a high general color rendering index Ra.

[0099] (Other embodiments) Although the embodiment has been described above, the present invention is not limited to the above embodiment.

[0100] For example, it is not essential that the three light sources other than the other light sources are a blue light source, a green light source, and a red light source. The three light sources may be three light sources having chromaticity values ​​that form a triangle that includes at least a part of the chromaticity range of the light source color on the chromaticity coordinates. The other light sources are not limited to a blue-green light source or a yellow light source.

[0101] In addition, in the above embodiments, the light emitted by the light source is realized by the light emitted from an LED or the fluorescence emitted by a phosphor, but it may also be realized by the light emitted from a semiconductor laser (laser light), the light emitted from an organic EL element (Electro-Luminescence), or the light emitted from an inorganic EL element, etc.

[0102] For example, in the above embodiment, the lighting system is realized by a plurality of devices, but may be realized as a single device. For example, the lighting system may be realized as a single device corresponding to the control device according to the above embodiment. When the lighting system is realized by a plurality of devices, the components of the lighting system described in the above embodiment may be distributed in any manner among the plurality of devices.

[0103] In the above embodiment, the processes executed by a specific processing unit may be executed by another processing unit. The order of multiple processes may be changed, or multiple processes may be executed in parallel.

[0104] In the above embodiment, each component may be realized by executing a software program suitable for each component. Each component may be realized by a program execution unit such as a CPU or a processor reading and executing a software program recorded on a recording medium such as a hard disk or a semiconductor memory.

[0105] Furthermore, each component may be realized by hardware. Each component may be a circuit (or an integrated circuit). These circuits may form a single circuit as a whole, or each may be a separate circuit. Furthermore, each of these circuits may be a general-purpose circuit, or a dedicated circuit.

[0106] Furthermore, the general or specific aspects of the present invention may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a computer-readable recording medium such as a CD-ROM, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

[0107] For example, the present invention may be realized as a lighting method executed by a computer such as a lighting system, or as a program for causing a computer to execute the lighting method, or as a computer-readable non-transitory recording medium on which such a program is recorded.

[0108] In addition, the present invention also includes forms obtained by applying various modifications to each embodiment that a person skilled in the art may think of, or forms realized by arbitrarily combining the components and functions of each embodiment within the scope that does not deviate from the spirit of the present invention. [Explanation of symbols]

[0109] 10, 10a Lighting system 20 Input Devices 30 Control device 31 Control Unit 32 Storage section 40, 40a Lighting equipment 41 Dimmer circuit 42, 42a Light source section 42b Blue light source 42bg Blue-green light source 42g green light source 42r red light source 42y yellow light source

Claims

1. A control unit is provided for controlling four light sources that emit light having different chromaticity values ​​from each other, On the chromaticity coordinate system, a quadrangular region having four vertices corresponding to the chromaticity values ​​of the light emitted by the four light sources includes at least a part of the chromaticity range of the light source color defined in JIS Z9112, The control unit is output light having a chromaticity value within a first region of a triangle having vertices that are the top three points among the four points that are closest to the blackbody locus, by emitting light from three light sources among the four light sources that correspond to the three vertices of the first region; output light having a chromaticity value within a triangular second region obtained by excluding the first region from the rectangular region is realized by emitting light from three light sources among the four light sources that correspond to three vertices of the second region; The four light sources include a red light source, a green light source, a blue light source, and another light source; The point indicating the chromaticity value of the other light source is included in all of the three vertices of the first region and all of the three vertices of the second region. Lighting system.

2. the other light source is another blue light source, the three vertices of the first region include a point indicating a chromaticity value of the other blue light source, a point indicating a chromaticity value of the red light source, and a point indicating a chromaticity value of the green light source; The three vertices of the second region include a point indicating the chromaticity value of the other blue light source, a point indicating the chromaticity value of the red light source, and a point indicating the chromaticity value of the blue light source.

10. The lighting system of claim 1.

3. the other light source is a yellow light source, the three vertices of the first region include a point indicating a chromaticity value of the yellow light source, a point indicating a chromaticity value of the blue light source, and a point indicating a chromaticity value of the red light source; The three vertices of the second region include a point indicating the chromaticity value of the yellow light source, a point indicating the chromaticity value of the blue light source, and a point indicating the chromaticity value of the green light source.

10. The lighting system of claim 1.

4. the three vertices of the first region include a point indicating a chromaticity value of the other light source, a point indicating a first chromaticity value, and a point indicating a second chromaticity value; a first point indicating a chromaticity value when each of the other light source and the light source corresponding to the point indicating the first chromaticity value is caused to emit light at maximum brightness is included on a line segment connecting the point indicating the chromaticity value of the other light source and the point indicating the first chromaticity value; a second point indicating a chromaticity value when each of the other light source and the light source corresponding to the point indicating the second chromaticity value is caused to emit light at maximum brightness is included on a line segment connecting the point indicating the chromaticity value of the other light source and the point indicating the second chromaticity value; a third point is included within the first region, the third point indicating a chromaticity value when each of three light sources corresponding to three vertices of the first region is caused to emit light at maximum brightness; the three vertices of the second region include a point indicating a chromaticity value of the other light source, a point indicating the second chromaticity value, and a point indicating a third chromaticity value; a fourth point indicating a chromaticity value when each of the other light source and the light source corresponding to the point indicating the third chromaticity value is caused to emit light at maximum brightness is included on a line segment connecting the point indicating the chromaticity value of the other light source and the point indicating the third chromaticity value; a fifth point is included within the second region, the fifth point indicating a chromaticity value when each of three light sources corresponding to the three vertices of the second region is caused to emit light at maximum brightness; the control unit causes the four light sources to emit light to produce output light having a chromaticity value located within a first target region and output light having a chromaticity value located within a second target region; the first target area is an area where an area surrounded by the points indicating the chromaticity values ​​of the other light source, the first points, the second points, and the third points overlaps with an area surrounded by the points indicating the first chromaticity values, the points indicating the second chromaticity values, and the points indicating the third chromaticity values; The second target area is an area where an area surrounded by the points indicating the chromaticity values ​​of the other light source, the second points, the fourth points, and the fifth points overlap with an area surrounded by the points indicating the first chromaticity value, the points indicating the second chromaticity value, and the points indicating the third chromaticity value.

4. The lighting system according to claim 1.

5. The control unit selectively executes a first mode control in which output light having a chromaticity value within the first target region is realized by causing three light sources corresponding to three vertices of the first region to emit light and output light having a chromaticity value within the second target region is realized by causing three light sources corresponding to three vertices of the second region to emit light, and a second mode control in which output light having a chromaticity value within the first target region and the second target region is realized by causing the four light sources to emit light.

5. A lighting system according to claim 4.

6. A control step of controlling four light sources emitting light having different chromaticity values ​​from each other, On the chromaticity coordinate system, a quadrangular region having four vertices corresponding to the chromaticity values ​​of the light emitted by the four light sources includes at least a part of the chromaticity range of the light source color defined in JIS Z9112, In the control step, output light having a chromaticity value within a first region of a triangle having vertices that are the top three points among the four points that are closest to the blackbody locus, by emitting light from three light sources among the four light sources that correspond to the three vertices of the first region; output light having a chromaticity value within a triangular second region obtained by excluding the first region from the rectangular region is realized by emitting light from three light sources among the four light sources that correspond to three vertices of the second region; The four light sources include a red light source, a green light source, a blue light source, and another light source; The point indicating the chromaticity value of the other light source is included in all of the three vertices of the first region and all of the three vertices of the second region. lighting method.

7. A program for causing a computer to execute the lighting method according to claim 6.

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