Illumination system, method and program for controlling illumination system

Abstract

This lighting system comprises: a plurality of light sources; a base material, a plurality of wavelength conversion units; a light guide unit; and a controller. The plurality of light sources include a first light source and a second light source. The plurality of wavelength conversion units are positioned on the base material, and include a first wavelength conversion unit and a second wavelength conversion unit. The light guide unit guides fluorescent light emitted from each of the wavelength conversion units. When causing each of the light sources to repeatedly execute emission and non-emission of excitation light at a fixed cycle, the controller performs control, during an operation period of one cycle, so as not to cause the second light source to emit the excitation light to the second wavelength conversion unit in at least a part of a first emission period in which the first light source emits the excitation light to the first wavelength conversion unit, and not to cause the first light source to emit the excitation light to the first wavelength conversion unit in at least a part of a second emission period in which the second light source emits the excitation light to the second wavelength conversion unit.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Japanese Application No. 2021-193457 (filed November 29, 2021), the entire disclosure of which is incorporated herein by reference. [Technical field]

[0002] The present disclosure relates to lighting technology. [Background technology]

[0003] A device is known in which light from a light source is irradiated onto a light-emitting section containing multiple types of phosphors, and the light that passes through the light-emitting section is mixed with two or more colors of fluorescence generated by the multiple types of phosphors to emit light of a desired color, such as white light (see, for example, the description in Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-155406 A Summary of the Invention

[0005] A lighting system, a method for controlling a lighting system, and a program are disclosed.

[0006] One aspect of the illumination system includes a plurality of light source units, a base material, a plurality of wavelength conversion units, a light guide unit, and a controller. The plurality of light source units each emit an excitation light and include a first light source unit and a second light source unit. The plurality of wavelength conversion units are located on the base material. The plurality of wavelength conversion units include a first wavelength conversion unit that emits fluorescence having a first wavelength spectrum in response to irradiation with the excitation light emitted from the first light source unit, and a second wavelength conversion unit that emits fluorescence having a second wavelength spectrum different from the first wavelength spectrum in response to irradiation with the excitation light emitted from the second light source unit. The light guide unit guides the fluorescence emitted by each of the plurality of wavelength conversion units. The controller causes each of the plurality of light source units to repeatedly emit and not emit excitation light at a constant cycle. When causing each of the plurality of light source units to repeatedly emit and not emit excitation light at a constant cycle, the controller, in an operation period of one cycle, does not cause the second light source unit to emit excitation light to the second wavelength conversion unit during at least a part of a first emission period in which the first light source unit emits excitation light to the first wavelength conversion unit, and does not cause the first light source unit to emit excitation light to the first wavelength conversion unit during at least a part of a second emission period in which the second light source unit emits excitation light to the second wavelength conversion unit. The operation period of one cycle is a period from a first start timing at which the first light source unit starts a first irradiation of the first wavelength conversion unit with excitation light to a second start timing at which the first light source unit starts a second irradiation of the first wavelength conversion unit with excitation light following the first irradiation of the first wavelength conversion unit with excitation light.

[0007] One aspect of the method for controlling a lighting system is a method for controlling a lighting system including a plurality of light source units, a base material, a plurality of wavelength conversion units, a light guide unit, and a controller, and includes a step of (a) causing each of the plurality of light source units to repeatedly emit and not emit excitation light at a constant cycle by the controller. The plurality of light source units each emit excitation light and include a first light source unit and a second light source unit. The plurality of wavelength conversion units are located on the base material. The plurality of wavelength conversion units include a first wavelength conversion unit that emits fluorescence having a first wavelength spectrum in response to irradiation with the excitation light emitted from the first light source unit, and a second wavelength conversion unit that emits fluorescence having a second wavelength spectrum different from the first wavelength spectrum in response to irradiation with the excitation light emitted from the second light source unit. The light guide unit guides the fluorescence emitted by each of the plurality of wavelength conversion units. The controller controls emission and non-emission of excitation light in each of the plurality of light source units. In the step (a), the controller, during an operation period of one cycle, does not cause the second light source unit to emit excitation light to the second wavelength conversion unit during at least a part of a first emission period in which the first light source unit emits excitation light to the first wavelength conversion unit, and does not cause the first light source unit to emit excitation light to the first wavelength conversion unit during at least a part of a second emission period in which the second light source unit emits excitation light to the second wavelength conversion unit. The operation period of one cycle is a period from a first start timing at which the first light source unit starts a first irradiation of the first wavelength conversion unit with excitation light to a second start timing at which the first light source unit starts a second irradiation of the first wavelength conversion unit with excitation light following the first irradiation of the first wavelength conversion unit with excitation light.

[0008] One aspect of the program is executed by the controller in an illumination system including a plurality of light source units, a base material, a plurality of wavelength conversion units, a light guide unit, and a controller, to cause the illumination system to function as the illumination system of the above aspect. The plurality of light source units each emit excitation light and include a first light source unit and a second light source unit. The plurality of wavelength conversion units are located on the base material. The plurality of wavelength conversion units include a first wavelength conversion unit that emits fluorescence having a first wavelength spectrum in response to irradiation with excitation light emitted from the first light source unit, and a second wavelength conversion unit that emits fluorescence having a second wavelength spectrum different from the first wavelength spectrum in response to irradiation with excitation light emitted from the second light source unit. The light guide unit guides the fluorescence emitted by each of the plurality of wavelength conversion units. The controller controls emission and non-emission of excitation light in each of the plurality of light source units. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing an example of the configuration of a lighting system according to a first embodiment. [Diagram 2] FIG. 2 is a schematic diagram showing an example of the configuration of the light emitting section, the conversion section, and the light guiding section. [Diagram 3] FIG. 3 is a schematic diagram showing an example of the configuration of the light emitting section and the conversion section. [Figure 4] FIG. 4 is a diagram showing a reference example of a period during which each of a plurality of light source units emits excitation light. [Diagram 5] FIG. 5 is a diagram showing an example of a period during which each of the plurality of light source units emits excitation light. [Figure 6] FIG. 6 is a diagram showing an example of a period during which each of the plurality of light source units emits excitation light. [Figure 7] FIG. 7 is a diagram showing an example of a period during which each of the plurality of light source units emits excitation light. [Figure 8] FIG. 8 is a diagram showing an example of a period during which each of the plurality of light source units emits excitation light. [Figure 9]FIG. 9 is a diagram showing an example of a period during which each of the plurality of light source units emits excitation light. [Figure 10] FIG. 10 is a diagram showing an example of a period during which each of the plurality of light source units emits excitation light. [Figure 11] FIG. 11 is a diagram showing an example of a period during which each of the plurality of light source units emits excitation light. [Figure 12] FIG. 12 is a diagram showing an example of a period during which each of the plurality of light source units emits excitation light. [Figure 13] FIG. 13 is a diagram showing an example of a period during which each of the plurality of light source units emits excitation light. [Figure 14] FIG. 14 is a diagram showing an example of a period during which each of the plurality of light source units emits excitation light. [Figure 15] FIG. 15 is a diagram showing an example of a period during which each of the plurality of light source units emits excitation light. [Figure 16] FIG. 16 is a diagram showing an example of a period during which each of the plurality of light source units emits excitation light. [Figure 17] FIG. 17 is a diagram showing an example of a period during which each of the plurality of light source units emits excitation light. [Figure 18] FIG. 18 is a diagram showing an example of a period during which each of the plurality of light source units emits excitation light. [Figure 19] FIG. 19 is a diagram showing a reference example of the relationship between the period during which each of the plurality of light source units emits excitation light and the fluctuation in the load of the power supply. [Figure 20] FIG. 20 is a diagram showing an example of the relationship between the period during which each of the plurality of light source units emits excitation light and the fluctuation in the load of the power supply. [Figure 21] FIG. 21 is a diagram showing an example of the relationship between the period during which each of the plurality of light source units emits excitation light and the fluctuation in the load of the power supply. [Figure 22] FIG. 22 is a schematic diagram showing the configuration of a lighting system according to another first example. [Figure 23] FIG. 23 is a diagram showing an example of a period during which each of a plurality of light source units emits excitation light in a lighting system according to another first example. [Figure 24] FIG. 24 is a schematic diagram showing the configuration of a lighting system according to another second example. [Diagram 25] FIG. 25 is a diagram showing an example of a period during which each of a plurality of light source units emits excitation light in a lighting system according to another second example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] There is a device in which excitation light from a light source is irradiated onto a light-emitting section that contains multiple types of phosphors, and the light that passes through the light-emitting section is mixed with the multiple colors of fluorescence generated by the multiple types of phosphors, emitting light of a desired color, such as white light.

[0011] In this device, multiple types of phosphors are present in a mixed state in the light-emitting section. Therefore, in order to adjust the color of the emitted light to a desired color, such as reddish or bluish white, it is possible to change the content ratio of multiple types of phosphors in the light-emitting section. However, this color-adjusting method does not allow color adjustment using a completed light-emitting section.

[0012] In order to adjust the color, for example, a device including a first light source, a first wavelength conversion unit including a first phosphor that emits fluorescence of a first color in response to the excitation light from the first light source, a second light source, a second wavelength conversion unit including a second phosphor that emits fluorescence of a second color different from the first color in response to the excitation light from the second light source, a third light source, and a third wavelength conversion unit including a third phosphor that emits fluorescence of a third color different from both the first color and the second color in response to the excitation light from the third light source is considered. In this device, for example, the emission period and intensity of the excitation light emitted from each of the first light source, the second light source, and the third light source are appropriately adjusted, and the first color fluorescence emitted from the first wavelength conversion unit, the second color fluorescence emitted from the second wavelength conversion unit, and the third color fluorescence emitted from the third wavelength conversion unit are mixed to adjust the color. Here, for example, purple is applied to the excitation light, red is applied to the first color, green is applied to the second color, and blue is applied to the third color.

[0013] However, the heating caused by the irradiation of the excitation light may cause the phosphor to deteriorate.

[0014] For this reason, there is room for improvement in the lighting system in terms of reducing degradation of phosphors while enabling adjustment of the color of the illumination light.

[0015] Therefore, the inventors of the present disclosure have created a technology for a lighting system that can reduce degradation of phosphors while enabling adjustment of the color of illumination light.

[0016] In the following, a first embodiment and various examples will be described with reference to the drawings. In the drawings, parts having the same or similar configurations and functions are given the same reference numerals, and duplicated explanations will be omitted in the following description. In the drawings, various structures and functional configurations are shown in schematic form.

[0017] <1. First embodiment> <1-1. Lighting system configuration> FIG. 1 is a schematic diagram showing an example of the configuration of a lighting system 1 according to a first embodiment. The lighting system 1 can synthesize multiple colors of fluorescence generated by irradiating multiple wavelength conversion units each including a phosphor with excitation light from multiple light source units, and radiate the synthesized fluorescence as illumination light into a predetermined space (also called an illumination space). The lighting system 1 may radiate illumination light into an indoor space, or may radiate illumination light into an outdoor space. In other words, the illumination light radiated by the lighting system 1 may be used indoors or outdoors. In addition, multiple lighting systems 1 may radiate illumination light into the same space, or multiple lighting systems 1 may radiate illumination light into multiple different spaces.

[0018] As shown in FIG. 1, the lighting system 1 includes, for example, a light emitting unit 2, a conversion unit 3, a light guiding unit 4, and a control device 5.

[0019] Fig. 2 is a schematic diagram showing an example of the configuration of the light emitting section 2, the conversion section 3, and the light guiding section 4. Fig. 2 shows an example of a schematic vertical cross-sectional view of the light emitting section 2, the conversion section 3, and the light guiding section 4. Fig. 3 is a schematic diagram showing an example of the configuration of the light emitting section 2 and the conversion section 3. Fig. 3 shows an example of a schematic plan view of the light emitting section 2 and the conversion section 3.

[0020] The light emitting unit 2 has, for example, a plurality of light source units 21. The plurality of light source units 21 can each emit, for example, excitation light L0. The plurality of light source units 21 each have a light emitting element. The light emitting element includes, for example, a laser diode (LD) or a light emitting diode (LED) chip. Monochromatic light such as purple, blue-purple, or blue is applied to the excitation light L0 emitted by the light emitting element. More specifically, a gallium nitride (GaN)-based semiconductor laser that emits purple laser light of 405 nanometers (nm) is applied to the light emitting element. The plurality of light source units 21 include, for example, a first light source unit (also referred to as a first light source unit) 211, a second light source unit (also referred to as a second light source unit) 212, and a third light source unit (also referred to as a third light source unit) 213. In the example of FIG. 2 and FIG. 3, the light emitting unit 2 is located in a state in which it is close to the conversion unit 3. In this case, the excitation light L0 emitted from each of the multiple light source sections 21 may be directly irradiated onto the conversion section 3, or may be irradiated via an optical element such as a collimator lens.

[0021] As shown in FIGS. 1 to 3, the conversion unit 3 has, for example, a base material 31 and a plurality of wavelength conversion units 32.

[0022] The base material 31 is, for example, a member to which the wavelength conversion units 32 are fixed. The base material 31 has, for example, a higher thermal conductivity than the wavelength conversion units 32. As a result, the base material 31 functions as a heat sink for cooling the wavelength conversion units 32. For example, a metal material is applied as the material of the base material 31. For example, copper (Cu), aluminum (Al), magnesium (Mg), gold (Au), silver (Ag), iron (Fe), chromium (Cr), cobalt (Co), beryllium (Be), molybdenum (Mo), tungsten (W), or an alloy is applied as the metal material. Here, for example, if Cu, Al, Mg, Fe, Cr, Co, or Be is adopted as the metal material, the base material 31 can be easily manufactured by a casting method such as die casting. Here, for example, if Al, Mg, Ag, Fe, Cr, or Co is adopted as the metal material, the reflectance of visible light on the surface of the base material 31 can be increased. Furthermore, as the material of the base material 31, for example, a nonmetallic material such as silicon nitride (Si3N4), carbon (C) or aluminum oxide (Al2O3) may be adopted. The nonmetallic material may be, for example, a material having crystallinity or an amorphous material having no crystallinity. As the nonmetallic material having crystallinity, for example, silicon carbide (SiC) or Si3N4 may be adopted.

[0023] 2 and 3, the base material 31 has a disk-shaped main body 31b and a plurality of protrusions 31p protruding from a first plate surface 31f of the main body 31b. A light source unit 21 is fixed onto each of the protrusions 31p. More specifically, the plurality of protrusions 31p include a first protrusion 31p to which the first light source unit 211 is fixed, a second protrusion 31p to which the second light source unit 212 is fixed, and a third protrusion 31p to which the third light source unit 213 is fixed.

[0024] The wavelength conversion units 32 are located on, for example, a base material 31. Each of the wavelength conversion units 32 is fixed to, for example, a surface of the base material 31 by adhesion or bonding. Each of the wavelength conversion units 32 may be fixed in, for example, a recess of the base material 31. The wavelength conversion units 32 include, for example, a first wavelength conversion unit (also referred to as a first wavelength conversion unit) 321, a second wavelength conversion unit (also referred to as a second wavelength conversion unit) 322, and a third wavelength conversion unit (also referred to as a third wavelength conversion unit) 323. Each of the wavelength conversion units 32 can emit fluorescence L1 in response to irradiation with, for example, excitation light L0 emitted from the light source unit 21.

[0025] The first wavelength conversion unit 321 can emit fluorescence (also referred to as first fluorescence) L11 having a first wavelength spectrum in response to irradiation with, for example, the excitation light L0 emitted from the first light source unit 211. The second wavelength conversion unit 322 can emit fluorescence (also referred to as second fluorescence) L12 having a second wavelength spectrum different from the first wavelength spectrum in response to irradiation with, for example, the excitation light L0 emitted from the second light source unit 212. The third wavelength conversion unit 323 can emit fluorescence (also referred to as third fluorescence) L13 having a third wavelength spectrum different from both the first wavelength spectrum and the second wavelength spectrum in response to irradiation with, for example, the excitation light L0 emitted from the third light source unit 213.

[0026] Here, for example, fluorescence having a different color temperature from each other may be applied to the first fluorescence L11 and the second fluorescence L12. Also, for example, fluorescence having a color temperature different from the color temperatures of both the first fluorescence L11 and the second fluorescence L12 may be applied to the third fluorescence L13. Specifically, for example, light having a first color temperature is applied to the first fluorescence L11. For example, light having a second color temperature is applied to the second fluorescence L12. For example, light having a third color temperature is applied to the third fluorescence L13.

[0027] Each of the wavelength conversion units 32 includes, for example, a solid member (also called a phosphor member) containing a phosphor. As the phosphor member, for example, a pellet-shaped member (also called a phosphor pellet) is adopted in which a large number of particles of a phosphor that each emits fluorescence in response to irradiation with the excitation light L0 are contained in a transparent material such as resin or glass. The wavelength conversion units 32 contain, for example, a large number of particles of phosphors different from each other. The phosphor member may have a structure in which a transparent substrate such as resin or glass and a phosphor pellet are laminated. For example, if the phosphor pellet is formed on the surface of the base material 31 by hot molding or the like, each of the wavelength conversion units 32 and the surface of the base material 31 can be directly bonded. Here, for example, when the phosphor pellet has a configuration in which a large number of particles of a phosphor are contained in low-melting point glass, the phosphor particles and the material of the base material 31 share oxygen, and the phosphor pellet and the surface of the base material 31 can be bonded.

[0028] The first wavelength conversion unit 321 includes, for example, a phosphor (also referred to as a first phosphor) that emits fluorescence of a first color in response to irradiation with the excitation light L0. For example, a phosphor (also referred to as a red phosphor) that emits fluorescence of red (R) in response to irradiation with the excitation light L0 is applied to the first phosphor. The second wavelength conversion unit 322 includes, for example, a phosphor (also referred to as a second phosphor) that emits fluorescence of a second color in response to irradiation with the excitation light L0. For example, a phosphor (also referred to as a green phosphor) that emits fluorescence of green (G) in response to irradiation with the excitation light L0 is applied to the second phosphor. The third wavelength conversion unit 323 includes, for example, a phosphor (also referred to as a third phosphor) that emits fluorescence of a third color in response to irradiation with the excitation light L0. For example, a phosphor (also referred to as a blue phosphor) that emits fluorescence of blue (B) in response to irradiation with the excitation light L0 is applied to the third phosphor.

[0029] The red phosphor may be, for example, a phosphor whose fluorescence emitted in response to irradiation with the excitation light L0 has a peak wavelength in the range of about 620 nm to 750 nm. Examples of materials for the red phosphor include CaAlSiN3:Eu, Y2O2S:Eu, Y2O3:Eu, and SrCaClAlSiN3:Eu. 2+, CaAlSiN3:Eu, or CaAlSi(ON)3:Eu, etc. are used as the green phosphor. For example, a phosphor whose peak wavelength of fluorescence emitted in response to irradiation with excitation light L0 is in the range of about 495 nm to 570 nm is used as the green phosphor. For example, β-SiAlON:Eu, SrSi2(O,Cl)2N2:Eu, (Sr,Ba,Mg)2SiO4:Eu2 2+ , ZnS:Cu,Al, or Zn2SiO4:Mn, etc. are used as the blue phosphor. For example, a phosphor that emits fluorescence in response to irradiation with excitation light L0 with a peak wavelength in the range of about 450 nm to 495 nm is used as the blue phosphor. For example, (Ba,Sr)MgAl 10 O 17 :Eu,BaMgAl 10 O 17 :Eu, (Sr,Ca,Ba) 10 (PO4)6Cl2:Eu or (Sr,Ba) 10 (PO4)6Cl2:Eu, etc. are applied. Here, the ratio of the elements in the parentheses can be set arbitrarily as long as it is within the range of the molecular formula. Here, for example, it is considered that the green phosphor, blue phosphor, and red phosphor are easily deteriorated by heating in the order of the description.

[0030] In the example of FIG. 2 and FIG. 3, a plurality of wavelength conversion units 32 are located on the first plate surface 31f of the main body 31b of the base material 31. The plurality of wavelength conversion units 32 are located adjacent to each other. The plurality of wavelength conversion units 32 may be in contact with each other or may be separated from each other. In the example of FIG. 2, a cylindrical housing unit 35 is located in a form surrounding the plurality of wavelength conversion units 32 from the side. The base material 31, for example, closes a first opening (also called a first opening) Op1 of the housing unit 35. For example, the lid unit 34 is located in a form closing a second opening (also called a second opening) Op2 of the housing unit 35 opposite to the first opening Op1. The housing unit 35, the base material 31, and the lid unit 34 are in a state of forming an internal space Sp1 sandwiched between the base material 31 and the lid unit 34 in the hollow portion of the housing unit 35. The material of each of the housing part 35 and the lid part 34 may be, for example, ceramics, resin, metal material, or nonmetal material. Fixation of the housing part 35 to the base material 31 and fixation of the housing part 35 to the lid part 34 may be achieved by any fixing method such as adhesion, bonding, fastening, and fitting.

[0031] The light guiding section 4 can guide, for example, the fluorescence L1 emitted by each of the multiple wavelength converting sections 32. For example, the light guiding section 4 can guide the fluorescence L1 emitted by each of the multiple wavelength converting sections 32 toward a predetermined lighting space. More specifically, for example, the light guiding section 4 can guide the first fluorescence L11 emitted by the first wavelength converting section 321, the second fluorescence L12 emitted by the second wavelength converting section 322, and the third fluorescence L13 emitted by the third wavelength converting section 323 toward the predetermined lighting space.

[0032] For example, an optical fiber is applied to the light guide section 4. The optical fiber has, for example, a core and a cladding that has a lower refractive index than the core and is positioned in a form that covers the periphery of the core. In this case, for example, the fluorescence L1 emitted from each of the multiple wavelength conversion sections 32 is incident on a first end (also referred to as a first end or an incident end) 4e in the longitudinal direction of the optical fiber. For example, an optical element such as a lens may be attached to the incident end 4e of the optical fiber, or a filter for reducing the incidence of the excitation light L0 into the optical fiber may be disposed. The optical fiber can transmit the fluorescence L1, for example, in the core along the longitudinal direction. More specifically, for example, the optical fiber can transmit the first fluorescence L11, the second fluorescence L12, and the third fluorescence L13 in the core along the longitudinal direction. The fluorescence L1 transmitted by the optical fiber is emitted from a second end (also referred to as a second end or an exit end) opposite to the incident end 4e in the longitudinal direction of the optical fiber. The length of the optical fiber in the longitudinal direction is set to, for example, about several tens of centimeters (cm) to several tens of meters (m).

[0033] The light guiding unit 4 can generate the illumination light L2, for example, by combining the fluorescence L1 emitted by each of the multiple wavelength conversion units 32. More specifically, the light guiding unit 4 can generate the illumination light L2, for example, by combining the first fluorescence L11 emitted by the first wavelength conversion unit 321, the second fluorescence L12 emitted by the second wavelength conversion unit 322, and the third fluorescence L13 emitted by the third wavelength conversion unit 323. The light guiding unit 4 can, for example, directly radiate the illumination light L2 into a predetermined illumination space, or can radiate the illumination light L2 into the predetermined illumination space via an optical element such as a lens or a diffusion plate.

[0034] 2, the lid 34 has a function as, for example, a connection part for connecting the light guiding part 4. For example, the optical fiber serving as the light guiding part 4 is inserted into a through hole 34h located at the center of the lid 34 with an incident end 4e of the optical fiber serving as the light guiding part 4 located in the internal space Sp1.

[0035] The control device 5 includes, for example, a controller 51 and a plurality of driving units 52.

[0036] The controller 51 can generally manage the operation of the control device 5 by controlling the other components of the control device 5. The controller 51 can also be referred to as a control circuit. The controller 51 includes at least one processor to provide control and processing power for performing various functions, as described in more detail below.

[0037] According to various embodiments, the at least one processor may be implemented in a single integrated circuit (IC) or in multiple communicatively coupled ICs and / or discrete circuits. The at least one processor may be implemented according to various known techniques.

[0038] In one embodiment, a processor includes one or more circuits or units configured to perform one or more data computing procedures or processes, e.g., by executing instructions stored in associated memory. In other embodiments, a processor may be firmware (e.g., discrete logic components) configured to perform one or more data computing procedures or processes.

[0039] According to various embodiments, the processor may include one or more processors, controllers, microprocessors, microcontrollers, application specific integrated circuits (ASICs), digital signal processors, programmable logic devices, field programmable gate arrays, or any combination of these devices or configurations, or other known devices and configurations, to perform the functions described below.

[0040] In this example, the controller 51 includes, for example, a CPU (Central Processing Unit) 511 and a storage unit 512. The storage unit 512 includes a non-transitory recording medium that can be read by the CPU 511, such as a ROM (Read Only Memory) and a RAM (Random Access Memory). The storage unit 512 stores a program Pg1 for controlling the control device 5 and the like. Various functions of the controller 51 are realized by the CPU 511 executing the program Pg1 in the storage unit 512. In other words, the program Pg1 is executed by the controller 51, so that the lighting system 1 functions as a lighting system 1 that can realize various controls.

[0041] The configuration of the controller 51 is not limited to the above example. For example, the controller 51 may include a plurality of CPUs 511. The controller 51 may include at least one DSP (Digital Signal Processor). All or some of the functions of the controller 51 may be realized by a hardware circuit that does not require software to realize the functions. The storage unit 512 may include a computer-readable non-transitory recording medium other than ROM and RAM. The storage unit 512 may include, for example, a small hard disk drive and / or an SSD (Solid State Drive).

[0042] The multiple driving units 52 can drive the multiple light source units 21 in response to an instruction from the controller 51. The driving unit 52 drives the light source unit 21 by supplying power from the power source 6 to the light source unit 21, causing the light source unit 21 to output the excitation light L0. The controller 51 can control each of the multiple light source units 21 through the multiple driving units 52. More specifically, for example, the controller 51 can control the timing at which each of the multiple light source units 21 emits the excitation light L0 by controlling the presence or absence of power supply from the power source 6 to the multiple light source units 21 through the multiple driving units 52. The driving unit 52 is composed of multiple electronic components including, for example, a semiconductor switching element such as a transistor that can switch the presence or absence of power supply from the power source 6 to the light source unit 21. The driving unit 52 can also be called a driving circuit.

[0043] The controller 51 can, for example, cause each of the multiple light source units 21 to repeatedly emit and not emit the excitation light L0 at a constant cycle. Emission of the excitation light L0 is an operation of emitting the excitation light L0. Non-emission of the excitation light L0 is an operation of not emitting the excitation light L0. More specifically, the controller 51 causes each of the multiple light source units 21 to repeatedly perform one cycle of operation consisting of emission and non-emission of the excitation light L0 many times through, for example, the multiple drive units 52. At this time, the controller 51 can, for example, change the pulse width of a signal for instructing each of the multiple drive units 52. Thereby, for example, control can be performed to adjust the ratio (also called the duty ratio) of the period during which each of the multiple light source units 21 emits the excitation light L0 during the period of one cycle of operation (also called the operation period of one cycle). The length of the operation period of one cycle (also called the time of one cycle) is set to a very short time, for example, about 0.5 milliseconds to several milliseconds. Here, for example, if the time of one cycle is T and the length (time) of the period during which the excitation light L0 is emitted by the light source unit 21 during the time T of one cycle is t, the duty ratio is expressed as a value (=t / T) obtained by dividing the time t by the time T. The duty ratio may be expressed, for example, as a percentage (=(t / T)×100[%]) of the ratio of the time t during which the excitation light L0 is emitted by the light source unit 21 during the time T of one cycle.

[0044] The multiple driving units 52 include, for example, a first driving unit (also referred to as a first driving unit) 521, a second driving unit (also referred to as a second driving unit) 522, and a third driving unit (also referred to as a third driving unit) 523. The first driving unit 521 can drive the first light source unit 211, for example, in response to an instruction from the controller 51. The second driving unit 522 can drive the second light source unit 212, for example, in response to an instruction from the controller 51. The third driving unit 523 can drive the third light source unit 213, for example, in response to an instruction from the controller 51.

[0045] For example, the controller 51 causes the first light source unit 211 to repeatedly perform a cycle consisting of emission and non-emission of the excitation light L0 through the first driving unit 521. At this time, the controller 51 can, for example, change the pulse width of a signal for instructing the first driving unit 521. Thereby, for example, control can be executed to adjust the ratio of the period during which the first light source unit 211 emits the excitation light L0 in the operation period of one cycle (also referred to as the duty ratio related to the first light source unit 211). In other words, the controller 51 can, for example, adjust the ratio of the period during which the first light source unit 211 emits the excitation light L0 (also referred to as the first emission period) to the period during which the first light source unit 211 does not emit the excitation light L0 in the operation period of one cycle. As a result, for example, it is possible to adjust the ratio between the period during which the first fluorescence L11 is emitted by the first wavelength conversion section 321 (also referred to as the first light-emitting period or the first on period) and the period during which the first fluorescence L11 is not emitted by the first wavelength conversion section 321 (also referred to as the first non-light-emitting period or the first off period).

[0046] For example, the controller 51 causes the second light source unit 212 to repeatedly perform a cycle consisting of emission and non-emission of the excitation light L0 through the second drive unit 522. At this time, the controller 51 can, for example, change the pulse width of a signal for instructing the second drive unit 522. Thereby, for example, control can be executed to adjust the ratio of the period during which the second light source unit 212 emits the excitation light L0 in one operation period (also referred to as the duty ratio related to the second light source unit 212). In other words, the controller 51 can, for example, adjust the ratio of the period during which the second light source unit 212 emits the excitation light L0 (also referred to as the second emission period) to the period during which the second light source unit 212 does not emit the excitation light L0 in one operation period. As a result, for example, it is possible to adjust the ratio between the period during which the second fluorescence L12 is emitted by the second wavelength conversion section 322 (also referred to as the second light emission period or the second on period) and the period during which the second fluorescence L12 is not emitted by the second wavelength conversion section 322 (also referred to as the second non-light emission period or the second off period).

[0047] For example, the controller 51 causes the third light source unit 213 to repeatedly perform a cycle consisting of emission and non-emission of the excitation light L0 through the third drive unit 523. At this time, the controller 51 can, for example, change the pulse width of a signal for instructing the third drive unit 523. Thereby, for example, control can be executed to adjust the ratio of the period during which the third light source unit 213 emits the excitation light L0 in one operation period (also referred to as the duty ratio related to the third light source unit 213). In other words, the controller 51 can, for example, adjust the ratio of the period during which the third light source unit 213 emits the excitation light L0 (also referred to as the third emission period) to the period during which the third light source unit 213 does not emit the excitation light L0 in one operation period. As a result, for example, it is possible to adjust the ratio between the period during which the third fluorescence L13 is emitted by the third wavelength conversion section 323 (also referred to as the third light emission period or the third on period) and the period during which the third fluorescence L13 is not emitted by the third wavelength conversion section 323 (also referred to as the third non-light emission period or the third off period).

[0048] The controller 51 can adjust the dimming and color of the illumination light L2 recognized by the human eye, for example, by adjusting the duty ratio of each of the multiple light source units 21. Dimming is adjusting the brightness of light. Color adjustment is adjusting the color of light. In the first embodiment, for example, the operation period Pc1 of one cycle includes a first emission period, a second emission period, and a third emission period. In other words, for example, in the operation period Pc1 of one cycle, the controller 51 causes the first light source unit 211 to emit the excitation light L0 to the first wavelength conversion unit 321, causes the second light source unit 212 to emit the excitation light L0 to the second wavelength conversion unit 322, and causes the third light source unit 213 to emit the excitation light L0 to the third wavelength conversion unit 323. For this reason, the controller 51 can adjust the ratio of the period in which the excitation light L0 is emitted and the period in which it is not emitted in each of the first light source unit 211, the second light source unit 212, and the third light source unit 213. This makes it possible to perform, for example, dimming and adjusting the color of the illumination light L2 as perceived by the human eye.

[0049] Here, for example, when the duty ratio of the first light source unit 211 is increased, the component of the first fluorescence L11 in the illumination light L2 increases. For example, when the duty ratio of the second light source unit 212 is increased, the component of the second fluorescence L12 in the illumination light L2 increases. For example, when the duty ratio of the third light source unit 213 is increased, the component of the third fluorescence L13 in the illumination light L2 increases. For example, when the duty ratio of the first light source unit 211 is reduced, the component of the first fluorescence L11 in the illumination light L2 decreases. For example, when the duty ratio of the second light source unit 212 is reduced, the component of the second fluorescence L12 in the illumination light L2 decreases. For example, when the duty ratio of the third light source unit 213 is reduced, the component of the third fluorescence L13 in the illumination light L2 decreases. The controller 51 can adjust the dimming and color of the illumination light L2 by, for example, individually adjusting the duty ratios of the multiple light source units 21. Such control for adjusting the light intensity and color by adjusting the duty ratio of each of the plurality of light source units 21 is also called PWM (Pulse Width Modulation) control.

[0050] <1-2. Lighting system control example> Fig. 4 is a diagram showing a reference example of a period during which each of the multiple light source units 21 emits the excitation light L0. Each of Figs. 5 to 18 is a diagram showing an example of a period during which each of the multiple light source units 21 emits the excitation light L0 in the lighting system 1 according to the first embodiment. In other words, each of Figs. 5 to 18 is a diagram showing an example of a method of controlling the lighting system 1 according to the first embodiment.

[0051] In the reference example of Fig. 4 and each of the examples of Fig. 5 to Fig. 18, the horizontal axis indicates time, and examples are shown in which each of the light source units 21 emits excitation light L0 in three consecutive one-cycle operation periods Pc1 out of many consecutive one-cycle operation periods Pc1. The three consecutive one-cycle operation periods Pc1 are composed of a first one-cycle operation period (also referred to as a first cycle operation period) Pc11, a second one-cycle operation period (also referred to as a second cycle operation period) Pc12, and a third one-cycle operation period (also referred to as a third cycle operation period) Pc13. Here, the operation period Pc1 of one cycle is a period from the timing (also referred to as the first start timing) when the first light source unit 211 starts irradiating the first wavelength conversion unit 321 with the excitation light L0 (also referred to as the first irradiation) to the timing (also referred to as the second start timing) when the first light source unit 211 starts irradiating the first wavelength conversion unit 321 with the excitation light L0 next to the first irradiation of the excitation light L0. The length of the operation period Pc1 of one cycle is the interval between the timings when the first light source unit 211 starts irradiating the first wavelength conversion unit 321 with the excitation light L0. In the first embodiment, the interval between the timings when the first light source unit 211 starts irradiating the first wavelength conversion unit 321 with the excitation light L0, the interval between the timings when the second light source unit 212 starts irradiating the second wavelength conversion unit 322 with the excitation light L0, and the interval between the timings when the third light source unit 213 starts irradiating the third wavelength conversion unit 323 with the excitation light L0 are the same.

[0052] In the reference example of FIG. 4 and the examples of FIG. 5 to FIG. 18, an operation period Pc1 of one cycle is composed of a plurality of unit periods P0 (for example, 10) that are consecutive in time. The length of the unit period P0 is set to a fixed time of, for example, about 0.1 milliseconds. The length of the operation period Pc1 of one cycle is set to a fixed time of, for example, about 1 millisecond.

[0053] Specifically, for example, the first cycle operation period Pc11 is composed of the first unit period (also called the first A unit period) A1 to the tenth unit period (also called the tenth A unit period) A10 as ten consecutive unit periods P0. The first A unit period A1 to the tenth A unit period A10 are composed of the first A unit period A1, the second unit period (also called the second A unit period) A2, the third unit period (also called the third A unit period) A3, the fourth unit period (also called the fourth A unit period) A4, the fifth unit period (also called the fifth A unit period) A5, the sixth unit period (also called the sixth A unit period) A6, the seventh unit period (also called the seventh A unit period) A7, the eighth unit period (also called the eighth A unit period) A8, the ninth unit period (also called the ninth A unit period) A9, and the tenth A unit period A10.

[0054] For example, the second cycle operation period Pc12 is composed of the first unit period (also called the 1st B unit period) B1 to the 10th unit period (also called the 10th B unit period) B10 as 10 consecutive unit periods P0. The 1st B unit period B1 to the 10th B unit period B10 are composed of the 1st B unit period B1, the 2nd unit period (also called the 2nd B unit period) B2, the 3rd unit period (also called the 3rd B unit period) B3, the 4th unit period (also called the 4th B unit period) B4, the 5th unit period (also called the 5th B unit period) B5, the 6th unit period (also called the 6th B unit period) B6, the 7th unit period (also called the 7th B unit period) B7, the 8th unit period (also called the 8th B unit period) B8, the 9th unit period (also called the 9th B unit period) B9, and the 10th B unit period B10.

[0055] For example, the third cycle operation period Pc13 is composed of the first unit period (also called the first C unit period) C1 to the tenth unit period (also called the tenth C unit period) C10 as ten consecutive unit periods P0. The first C unit period C1 to the tenth C unit period C10 are composed of the first C unit period C1, the second unit period (also called the second C unit period) C2, the third unit period (also called the third C unit period) C3, the fourth unit period (also called the fourth C unit period) C4, the fifth unit period (also called the fifth C unit period) C5, the sixth unit period (also called the sixth C unit period) C6, the seventh unit period (also called the seventh C unit period) C7, the eighth unit period (also called the eighth C unit period) C8, the ninth unit period (also called the ninth C unit period) C9, and the tenth C unit period C10.

[0056] Here, for example, the period from the start of the 1A unit period A1 to the start of the 1B unit period B1, and the period from the start of the 1B unit period B1 to the start of the 1C unit period C1 each constitute one cycle of operation period Pc1. The number of unit periods P0 constituting one cycle of operation period Pc1 may be any number other than 10, for example, 2 or more.

[0057] 4 to 18, the period (first emission period) during which the first light source unit 211 emits the excitation light L0 is indicated by a rectangle hatched with diagonal lines going up to the right. The period (third emission period) during which the third light source unit 213 emits the excitation light L0 is indicated by a rectangle hatched with diagonal lines going up to the left. The period (second emission period) during which the second light source unit 212 emits the excitation light L0 is indicated by a rectangle hatched with sand. In each example of Figures 4 to 18, the operating period Pc1 of one cycle includes a first emission period in which the first light source unit 211 emits excitation light L0 to the first wavelength conversion unit 321, a second emission period in which the second light source unit 212 emits excitation light L0 to the second wavelength conversion unit 322, and a third emission period in which the third light source unit 213 emits excitation light L0 to the third wavelength conversion unit 323.

[0058] In the reference example of FIG. 4 and the examples of FIG. 5 to FIG. 12, the first emission period, the second emission period, and the third emission period are periods of the same length in the operation period Pc1 of one cycle. Specifically, in the reference example of FIG. 4 and the examples of FIG. 5 to FIG. 7, the duty ratios of the first light source unit 211, the second light source unit 212, and the third light source unit 213 are 0.5. In the examples of FIG. 8 to FIG. 10, the duty ratios of the first light source unit 211, the second light source unit 212, and the third light source unit 213 are 0.2, which is an example of a value smaller than 0.5. For example, a value larger than 0 and smaller than 0.5, such as 0.1, 0.3, or 0.4, may be applied as the duty ratio value smaller than 0.5. 11 and 12, the duty ratio for each of the first light source unit 211, the second light source unit 212, and the third light source unit 213 is 0.8, which is an example of a value greater than 0.5. For example, a value greater than 0.5 and less than 1, such as 0.6, 0.7, or 0.9, may be applied as the duty ratio value greater than 0.5.

[0059] In each example of Fig. 13 to Fig. 18, in the operation period Pc1 of one cycle, the first emission period, the second emission period, and the third emission period are periods of different lengths. Specifically, in each example of Fig. 13 and Fig. 14, the duty ratio of the first light source unit 211 is 0.1, the duty ratio of the third light source unit 213 is 0.3, and the duty ratio of the second light source unit 212 is 0.5. In the example of Fig. 15, the duty ratio of the first light source unit 211 is 0.3, the duty ratio of the third light source unit 213 is 0.5, and the duty ratio of the second light source unit 212 is 0.7. In each example of Fig. 16 and Fig. 17, the duty ratio of the first light source unit 211 is 0.5, the duty ratio of the third light source unit 213 is 0.3, and the duty ratio of the second light source unit 212 is 0.1. In the example of FIG. 18, the duty ratio of the first light source section 211 is 0.7, the duty ratio of the third light source section 213 is 0.5, and the duty ratio of the second light source section 212 is 0.1.

[0060] In the reference example of FIG. 4, the first light source section 211, the second light source section 212, and the third light source section 213 simultaneously repeatedly perform emission and non-emission. In the first cycle operation period Pc11, the first light source section 211, the second light source section 212, and the third light source section 213 each emit the excitation light L0 from the 1A unit period A1 to the 5A unit period A5. In the second cycle operation period Pc12, the first light source section 211, the second light source section 212, and the third light source section 213 each emit the excitation light L0 from the 1B unit period B1 to the 5B unit period B5. In the third cycle operation period Pc13, the first light source section 211, the second light source section 212, and the third light source section 213 each emit the excitation light L0 from the 1C unit period C1 to the 5C unit period C5.

[0061] In the control of the reference example in Fig. 4, the first wavelength conversion section 321, the second wavelength conversion section 322, and the third wavelength conversion section 323 are heated simultaneously by irradiation of the excitation light L0 by each of the first light source section 211, the second light source section 212, and the third light source section 213. In this case, for example, the base material 31 functioning as a heat sink cools all three wavelength conversion sections 32 simultaneously, so that the three wavelength conversion sections 32 are difficult to cool. As a result, for example, the phosphors of the three wavelength conversion sections 32 are easily deteriorated by heating.

[0062] In response to this, for example, as shown in each example of FIG. 5 to FIG. 18, in the operation period Pc1 of one cycle, the first emission period and the second emission period may be shifted from each other. In this case, the controller 51 causes each of the multiple light source units 21 to repeatedly emit and not emit the excitation light L0 at a constant cycle. At that time, in the operation period Pc1 of one cycle, the controller 51 does not cause the second light source unit 212 to emit the excitation light L0 to the second wavelength conversion unit 322 during at least a part of the first emission period in which the first light source unit 211 emits the excitation light L0 to the first wavelength conversion unit 321. Then, in the operation period Pc1 of one cycle, the controller 51 does not cause the first light source unit 211 to emit the excitation light L0 to the first wavelength conversion unit 321 during at least a part of the second emission period in which the second light source unit 212 emits the excitation light L0 to the second wavelength conversion unit 322.

[0063] 5 to 18, the control method for the lighting system 1 includes a step of causing each of the multiple light source units 21 to repeatedly emit and not emit the excitation light L0 at a constant cycle by the controller 51. In this step, in an operation period Pc1 of one cycle, the controller 51 causes the second light source unit 212 not to emit the excitation light L0 to the second wavelength converter 322 during at least a part of the first emission period, and causes the first light source unit 211 not to emit the excitation light L0 to the first wavelength converter 321 during at least a part of the second emission period.

[0064] According to such control, for example, the period during which the first wavelength-converting section 321 and the second wavelength-converting section 322 are heated simultaneously is shortened. As a result, for example, the temperatures of the first wavelength-converting section 321 and the second wavelength-converting section 322 are less likely to rise, and deterioration of the phosphors in the first wavelength-converting section 321 and the second wavelength-converting section 322 can be reduced. Therefore, for example, in the lighting system 1 capable of adjusting the color, deterioration of the phosphors can be reduced.

[0065] FIG. 19 is a diagram showing a reference example of the relationship between the period during which each of the multiple light source units 21 emits the excitation light L0 and the fluctuation of the load (also called the power supply load) of the power supply 6. In FIG. 19, the fluctuation of the power supply load in the control of the reference example of FIG. 4 is shown by a thick line. Each of FIG. 20 and FIG. 21 is a diagram showing an example of the relationship between the period during which each of the multiple light source units 21 emits the excitation light L0 and the fluctuation of the load (power supply load) of the power supply 6. In FIG. 20, the fluctuation of the power supply load in the control of the example of FIG. 5 is shown by a thick line. In FIG. 21, the fluctuation of the power supply load in the control of the example of FIG. 7 is shown by a thick line. In each of FIG. 19 to FIG. 21, the horizontal axis indicates time, and the vertical axis of the power supply load typically indicates the magnitude of the power supply load. The magnitude of the power supply load may be, for example, a current or power supplied to the multiple light source units 21.

[0066] As shown in FIG. 19, if the first light source unit 211, the second light source unit 212, and the third light source unit 213 simultaneously repeat emission and non-emission, the instantaneous change in the power load becomes large. Specifically, in one reference example of FIG. 19, the power load changes instantaneously from 0 to 3 and from 3 to 0. In order to realize such an instantaneous large change in the power load, a high-performance power source (also called a high-speed high-performance power source) that can respond quickly and has excellent durability is required. In contrast, for example, as shown in FIG. 20 and FIG. 21, even if the first emission period and the second emission period are shifted, or even if the first emission period, the third emission period, and the second emission period are shifted, the instantaneous change in the power load can be reduced. Specifically, in each example of FIG. 20 and FIG. 21, the instantaneous change in the power load is only a relatively small change from 1 to 2 and from 2 to 1. Therefore, for example, as described above, if the control is executed to shift the first emission period and the second emission period from each other in the operation period Pc1 of one cycle as shown in each example of Figures 5 to 18, the instantaneous change in the power supply load can be reduced. This, for example, eliminates the need for a high-speed, high-performance power supply, and the power supply 6 is less likely to deteriorate. As a result, for example, the reliability of the power supply 6 and the lighting system 1 can be improved at low cost.

[0067] Incidentally, here, for example, as shown in each example of Figure 5, Figure 6, Figure 8, Figure 9, Figure 12, Figure 14 and Figure 17, in the operation period Pc1 of one cycle, the first emission period, the second emission period and the third emission period may be shifted from each other. In this case, in the operation period Pc1 of one cycle, the controller 51 does not cause the third light source unit 213 to emit the excitation light L0 to the third wavelength conversion unit 323 during at least a part of the first emission period, and does not cause the first light source unit 211 to emit the excitation light L0 to the first wavelength conversion unit 321 during at least a part of the third emission period. In the operation period Pc1 of one cycle, the controller 51 does not cause the third light source unit 213 to emit the excitation light L0 to the third wavelength conversion unit 323 during at least a part of the second emission period, and does not cause the second light source unit 212 to emit the excitation light L0 to the second wavelength conversion unit 322 during at least a part of the third emission period.

[0068] According to such control, for example, the first wavelength conversion section 321, the second wavelength conversion section 322, and the third wavelength conversion section 323 are less likely to be simultaneously irradiated with the excitation light L0. As a result, for example, the temperatures of the first wavelength conversion section 321, the second wavelength conversion section 322, and the third wavelength conversion section 323 are less likely to rise, and deterioration of the phosphors in the first wavelength conversion section 321, the second wavelength conversion section 322, and the third wavelength conversion section 323 can be reduced. Therefore, for example, in the lighting system 1 capable of adjusting the color, deterioration of the phosphors can be reduced.

[0069] Here, as shown in the examples of Fig. 8, Fig. 9, Fig. 14 and Fig. 17, the first emission period, the second emission period and the third emission period may not overlap each other. In this case, the controller 51 does not allow either the second light source unit 212 or the third light source unit 213 to emit the excitation light L0 to the second wavelength conversion unit 322 and the third wavelength conversion unit 323 during the first emission period. The controller 51 does not allow either the first light source unit 211 or the second light source unit 212 to emit the excitation light L0 to the first wavelength conversion unit 321 and the second wavelength conversion unit 322 during the third emission period. The controller 51 does not allow either the first light source unit 211 or the third light source unit 213 to emit the excitation light L0 to the first wavelength conversion unit 321 and the third wavelength conversion unit 323 during the second emission period.

[0070] According to such control, for example, the excitation light L0 is not irradiated simultaneously to two or more wavelength conversion units 32 among the first wavelength conversion unit 321, the second wavelength conversion unit 322, and the third wavelength conversion unit 323. As a result, for example, the temperatures of the first wavelength conversion unit 321, the second wavelength conversion unit 322, and the third wavelength conversion unit 323 are unlikely to rise, and deterioration of the phosphors in the first wavelength conversion unit 321, the second wavelength conversion unit 322, and the third wavelength conversion unit 323 can be reduced. Therefore, for example, in the lighting system 1 capable of adjusting the color, deterioration of the phosphors can be reduced.

[0071] Here, as shown in the example of FIG. 8, the first emission period and the third emission period are separated from each other, the third emission period and the second emission period are separated from each other, and the second emission period and the first emission period are separated from each other. 1The emission periods may be separated from each other. In this case, the controller 51 does not allow any of the plurality of light source units 21 to emit the excitation light L0 to the plurality of wavelength conversion units 32 in each of the period between the first emission period and the third emission period, the period between the third emission period and the second emission period, and the period after the second emission period in the operation period Pc1 of one cycle. Here, in the operation period Pc1 of one cycle, the period between the first emission period and the third emission period, the period between the third emission period and the second emission period, and the period after the second emission period are each a period (also called a non-emission period) in which the excitation light L0 is not emitted by the plurality of light source units 21. The period between the first emission period and the third emission period in the operation period Pc1 of one cycle may be called a first non-emission period. The period between the third emission period and the second emission period in the operation period Pc1 of one cycle may be called a second non-emission period. The period following the second emission period in the operation period Pc1 of one cycle may be referred to as the third non-emission period. Therefore, the controller 51 does not allow any of the first light source unit 211, the second light source unit 212, and the third light source unit 213 to emit the excitation light L0 to the first wavelength conversion unit 321, the second wavelength conversion unit 322, and the third wavelength conversion unit 323 in the first non-emission period, the second non-emission period, and the third non-emission period in the operation period Pc1 of one cycle. According to such control, for example, the temperatures of the first wavelength conversion unit 321, the second wavelength conversion unit 322, and the third wavelength conversion unit 323 are unlikely to rise. Here, for example, in the operation period Pc1 of one cycle, the first emission period, the second emission period, and the third emission period may be periods having different lengths.

[0072] Further, here, as shown in the example of FIG. 8, the second non-emission period may be longer than both the first non-emission period and the third non-emission period. In this case, for example, after the irradiation of the excitation light L0 to the third wavelength conversion unit 323 is finished, the irradiation of the excitation light L0 to the second wavelength conversion unit 322 may be started in a state in which the base material 31 as a heat sink is cooled. Thereby, for example, the temperature of the second wavelength conversion unit 322 is less likely to rise. As a result, for example, in the lighting system 1 capable of adjusting the color, when the phosphor of the second wavelength conversion unit 322 is more susceptible to deterioration due to heating than the phosphors of the first wavelength conversion unit 321 and the third wavelength conversion unit 323, deterioration of the phosphor can be reduced. Here, for example, in the operation period Pc1 of one cycle, the first emission period, the second emission period, and the third emission period may be periods of different lengths.

[0073] Also, here, for example, the control in the example of FIG. 8 may be changed to the control in the example of FIG. 9. In this case, the controller 51 does not cause the first non-emission period to occur between the first emission period and the third emission period in the operation period Pc1 of one cycle. The controller 51 does not cause any of the first light source unit 211, the second light source unit 212, and the third light source unit 213 to emit the excitation light L0 to the first wavelength conversion unit 321, the second wavelength conversion unit 322, and the third wavelength conversion unit 323 in the second non-emission period and the third non-emission period in the operation period Pc1 of one cycle. Here, the second non-emission period is longer than the third non-emission period.

[0074] According to such control, for example, before the second wavelength conversion unit 322 starts being irradiated with the excitation light L0, the base material 31 is easily cooled as a heat sink. Also, for example, after the second wavelength conversion unit 322 finishes being irradiated with the excitation light L0, the base material 31 is cooled a little, and then the first wavelength conversion unit 321 starts being irradiated with the excitation light L0. Therefore, the second wavelength conversion unit 322 is less likely to be heated through the base material 31. As a result, for example, in the lighting system 1 capable of adjusting color, when the phosphor of the second wavelength conversion unit 322 is more susceptible to deterioration due to heating than the phosphors of the first wavelength conversion unit 321 and the third wavelength conversion unit 323, deterioration of the phosphor can be reduced. Here, for example, in the operation period Pc1 of one cycle, the first emission period, the second emission period, and the third emission period may be periods of different lengths.

[0075] From another perspective, for example, as shown in each example of Fig. 5 to Fig. 18, in the operation period Pc1 of one cycle, at least a part of the second emission period may not overlap with either the first emission period or the third emission period. In this case, the controller 51 does not cause either the first light source unit 211 or the third light source unit 213 to emit the excitation light L0 to the first wavelength converter 321 and the third wavelength converter 323 during at least a part of the second emission period in the operation period Pc1 of one cycle.

[0076] According to such control, for example, the temperature of the second wavelength-converting unit 322 is less likely to increase. As a result, for example, in the lighting system 1 capable of adjusting color, when the phosphor of the second wavelength-converting unit 322 is more susceptible to deterioration due to heating than the phosphors of the first wavelength-converting unit 321 and the third wavelength-converting unit 323, deterioration of the phosphor can be reduced.

[0077] Here, for example, as shown in each of the examples of Figures 5 to 7, 10 to 13, 15, 16, and 18, the operation period Pc1 of one cycle may have a period in which the first emission period and the third emission period overlap each other. In this case, the controller 51 causes the third light source unit 213 to emit the excitation light L0 to the third wavelength converter 323 during at least a part of the first emission period of the operation period Pc1 of one cycle.

[0078] According to such control, for example, in the second emission period in which the second wavelength conversion unit 322 is irradiated with the excitation light L0, the period in which the excitation light L0 is not irradiated to both the first wavelength conversion unit 321 and the third wavelength conversion unit 323 can be lengthened. This makes it difficult for the temperature of the second wavelength conversion unit 322 to increase. As a result, for example, in the lighting system 1 capable of adjusting color, when the phosphor of the second wavelength conversion unit 322 is more susceptible to deterioration due to heating than the phosphors of the first wavelength conversion unit 321 and the third wavelength conversion unit 323, deterioration of the phosphor can be reduced.

[0079] Here, for example, as shown in each example of Figures 7, 10, 11, 13, 15, 16, and 18, in the operation period Pc1 of one cycle, the third emission period may be included in the first emission period, or the first emission period may be included in the third emission period. In this case, in the operation period Pc1 of one cycle, the controller 51 may start and end the emission of the excitation light L0 by the third light source unit 213 to the third wavelength conversion unit 323 in the first emission period, or may start and end the emission of the excitation light L0 by the first light source unit 211 to the first wavelength conversion unit 321 in the third emission period. In addition, the controller 51 may simultaneously start and end the emission of the excitation light L0 by each of the first light source unit 211 and the third light source unit 213 in the operation period Pc1 of one cycle.

[0080] According to such control, for example, in the second emission period in which the second wavelength conversion unit 322 is irradiated with the excitation light L0, the period in which the excitation light L0 is not irradiated to both the first wavelength conversion unit 321 and the third wavelength conversion unit 323 can be further extended. This makes it difficult for the temperature of the second wavelength conversion unit 322 to increase, for example. As a result, for example, in the lighting system 1 capable of adjusting color, when the phosphor of the second wavelength conversion unit 322 is more susceptible to deterioration due to heating than the phosphors of the first wavelength conversion unit 321 and the third wavelength conversion unit 323, deterioration of the phosphor can be reduced.

[0081] Here, for example, as shown in each example of Figures 7, 10, 11, 13, 15, 16, and 18, in the operation period Pc1 of one cycle, there may be no non-emission period after the second emission period. In this case, the controller 51 does not cause any of the first light source unit 211, the second light source unit 212, and the third light source unit 213 to emit the excitation light L0 to the first wavelength conversion unit 321, the second wavelength conversion unit 322, and the third wavelength conversion unit 323 (non-emission period) after the second emission period in the operation period Pc1 of one cycle.

[0082] According to such control, for example, in the second emission period in which the excitation light L0 is irradiated to the second wavelength conversion unit 322, the period in which the excitation light L0 is not irradiated to both the first wavelength conversion unit 321 and the third wavelength conversion unit 323 may become longer. This makes it difficult for the temperature of the second wavelength conversion unit 322 to increase. As a result, for example, in the lighting system 1 capable of adjusting color, when the phosphor of the second wavelength conversion unit 322 is more susceptible to deterioration due to heating than the phosphors of the first wavelength conversion unit 321 and the third wavelength conversion unit 323, deterioration of the phosphor may be reduced.

[0083] Here, for example, as shown in each example of Figures 7, 10, 13, 16, and 18, in the operation period Pc1 of one cycle, neither the first emission period nor the third emission period may overlap with the second emission period. In this case, the controller 51 does not cause either the first light source unit 211 or the third light source unit 213 to emit the excitation light L0 to the first wavelength converter 321 and the third wavelength converter 323 during the second emission period in the operation period Pc1 of one cycle.

[0084] According to such control, for example, it becomes more difficult for the temperature of the second wavelength-converting unit 322 to rise. As a result, for example, in the lighting system 1 capable of adjusting color, when the phosphor of the second wavelength-converting unit 322 is more susceptible to deterioration due to heating than the phosphors of the first wavelength-converting unit 321 and the third wavelength-converting unit 323, deterioration of the phosphor can be further reduced.

[0085] Here, for example, as shown in each example of Figures 10, 13, 16 and 18, in the operation period Pc1 of one cycle, a non-emission period may be provided between the first emission period and the third emission period and the second emission period. In this case, in the operation period Pc1 of one cycle, the controller 51 does not cause any of the first light source unit 211, the second light source unit 212 and the third light source unit 213 to emit the excitation light L0 to the first wavelength conversion unit 321, the second wavelength conversion unit 322 and the third wavelength conversion unit 323 in the period (non-emission period) between the first emission period and the third emission period and the second emission period.

[0086] According to such control, for example, the base material 31 can be cooled well before the second wavelength conversion unit 322 is irradiated with the excitation light L0. This makes it difficult for the temperature of the second wavelength conversion unit 322 to rise. As a result, for example, in the lighting system 1 capable of adjusting color, when the phosphor of the second wavelength conversion unit 322 is more susceptible to deterioration due to heating than the phosphors of the first wavelength conversion unit 321 and the third wavelength conversion unit 323, deterioration of the phosphor can be further reduced.

[0087] Here, the control by the controller 51 in each of the examples of FIG. 5 to FIG. 18 will be specifically described.

[0088] In the example of FIG. 5, under the control of the controller 51, in the operation period Pc1 of one cycle, the first light source unit 211 emits the excitation light L0 to the first wavelength conversion unit 321 in the first to fifth unit periods P0, the third light source unit 213 emits the excitation light L0 to the third wavelength conversion unit 323 in the third to seventh unit periods P0, and the second light source unit 212 emits the excitation light L0 to the second wavelength conversion unit 322 in the first, second, and eighth to tenth unit periods P0. According to the control of the example of FIG. 5, for example, after the irradiation of the excitation light L0 to the first wavelength conversion unit 321 is completed, the irradiation of the excitation light L0 to the second wavelength conversion unit 322 may be started in a state in which the base material 31 is cooled to a certain degree. As a result, for example, the temperature of the second wavelength conversion unit 322 is unlikely to rise, and deterioration of the phosphor in the second wavelength conversion unit 322 may be reduced.

[0089] In the example of Fig. 6, under the control of the controller 51, in the operation period Pc1 of one cycle, the first light source unit 211 emits the excitation light L0 to the first wavelength conversion unit 321 in the first to fifth unit periods P0, the third light source unit 213 emits the excitation light L0 to the third wavelength conversion unit 323 in the second to sixth unit periods P0, and the second light source unit 212 emits the excitation light L0 to the second wavelength conversion unit 322 in the first and seventh to tenth unit periods P0. According to the control of the example of Fig. 6, for example, after the irradiation of the excitation light L0 to the first wavelength conversion unit 321 is completed, the irradiation of the excitation light L0 to the second wavelength conversion unit 322 is started in a state in which the base material 31 is slightly cooled, and the irradiation of the excitation light L0 to each of the first wavelength conversion unit 321 and the third wavelength conversion unit 323 is not performed during most of the second emission period in which the excitation light L0 is irradiated to the second wavelength conversion unit 322. As a result, for example, the temperature of the second wavelength-converter 322 is less likely to increase, and deterioration of the phosphor in the second wavelength-converter 322 can be reduced.

[0090] In the example of Fig. 7, by the control of the controller 51, in the operation period Pc1 of one cycle, the first light source unit 211 emits the excitation light L0 to the first wavelength conversion unit 321, and the third light source unit 213 emits the excitation light L0 to the third wavelength conversion unit 323 in the first to fifth unit periods P0, and the second light source unit 212 emits the excitation light L0 to the second wavelength conversion unit 322 in the sixth to tenth unit periods P0. According to the control of the example of Fig. 7, for example, the first emission period and the third emission period coincide with each other, and the first emission period and the third emission period do not overlap in the second emission period. As a result, for example, the temperature of the second wavelength conversion unit 322 is unlikely to rise, and deterioration of the phosphor in the second wavelength conversion unit 322 can be reduced.

[0091] 8, under the control of the controller 51, in an operation period Pc1 of one cycle, the first light source unit 211 emits excitation light L0 to the first wavelength conversion unit 321 in the first and second unit periods P0, the third light source unit 213 emits excitation light L0 to the third wavelength conversion unit 323 in the fourth and fifth unit periods P0, and the second light source unit 212 emits excitation light L0 to the second wavelength conversion unit 322 in the eighth and ninth unit periods P0. According to the control of the example of FIG. 8, for example, in the operation period Pc1 of one cycle, a non-emission period constituted by two unit periods P0 between the third emission period and the second emission period is longer than a non-emission period constituted by one unit period P0 between the first emission period and the third emission period. Thereby, for example, the temperatures of the first wavelength-converting section 321, the second wavelength-converting section 322, and the third wavelength-converting section 323 are unlikely to rise, and irradiation of the excitation light L0 to the second wavelength-converting section 322 can be started in a cooled state of the base material 31 after irradiation of the excitation light L0 to the third wavelength-converting section 323 is completed. As a result, for example, the temperature of the second wavelength-converting section 322 is unlikely to rise, and deterioration of the phosphor in the second wavelength-converting section 322 can be reduced.

[0092] In the example of FIG. 9, under the control of the controller 51, in the operation period Pc1 of one cycle, the first light source unit 211 emits the excitation light L0 to the first wavelength conversion unit 321 in the first and second unit periods P0, the third light source unit 213 emits the excitation light L0 to the third wavelength conversion unit 323 in the third and fourth unit periods P0, and the second light source unit 212 emits the excitation light L0 to the second wavelength conversion unit 322 in the eighth and ninth unit periods P0. According to the control of the example of FIG. 9, for example, in the operation period Pc1 of one cycle, the non-emission period consisting of three unit periods P0 between the third emission period and the second emission period is longer than the non-emission period consisting of one unit period P0 after the second emission period. As a result, for example, after the irradiation of the excitation light L0 to the third wavelength conversion unit 323 is completed, the irradiation of the excitation light L0 to the second wavelength conversion unit 322 can be started in a state in which the base material 31 is cooled. As a result, for example, the temperature of the second wavelength-converter 322 is less likely to increase, and deterioration of the phosphor in the second wavelength-converter 322 can be reduced.

[0093] In the example of Fig. 10, under the control of the controller 51, in the operation period Pc1 of one cycle, the first light source unit 211 emits the excitation light L0 to the first wavelength conversion unit 321 in the first and second unit periods P0, the third light source unit 213 emits the excitation light L0 to the third wavelength conversion unit 323, and the second light source unit 212 emits the excitation light L0 to the second wavelength conversion unit 322 in the ninth and tenth unit periods P0. According to the control of the example of Fig. 10, for example, in the longest possible non-emission period consisting of six unit periods P0 between the first emission period and the third emission period and the second emission period that completely overlap each other, irradiation of the excitation light L0 to the second wavelength conversion unit 322 can be started in a state in which the base material 31 is well cooled. As a result, for example, the temperature of the second wavelength conversion unit 322 is unlikely to rise, and deterioration of the phosphor in the second wavelength conversion unit 322 can be reduced.

[0094] In the example of Fig. 11, under the control of the controller 51, in the operation period Pc1 of one cycle, the first light source unit 211 emits the excitation light L0 to the first wavelength conversion unit 321, and the third light source unit 213 emits the excitation light L0 to the third wavelength conversion unit 323 in the first to eighth unit periods P0, and the second light source unit 212 emits the excitation light L0 to the second wavelength conversion unit 322 in the first to sixth, ninth and tenth unit periods P0. According to the control of the example of Fig. 11, for example, the period during which the first emission period and the third emission period overlap in the second emission period can be shortened. As a result, for example, the temperature of the second wavelength conversion unit 322 is less likely to rise, and the deterioration of the phosphor in the second wavelength conversion unit 322 can be reduced.

[0095] In the example of FIG. 12, under the control of the controller 51, in the operation period Pc1 of one cycle, the first light source unit 211 emits the excitation light L0 to the first wavelength conversion unit 321 in the first to eighth unit periods P0, the third light source unit 213 emits the excitation light L0 to the third wavelength conversion unit 323 in the second to ninth unit periods P0, and the second light source unit 212 emits the excitation light L0 to the second wavelength conversion unit 322 in the third to tenth unit periods P0. According to the control of the example of FIG. 12, for example, the start and end timings are shifted between the first emission period, the second emission period, and the third emission period. This can reduce, for example, an instantaneous change in the power supply load. This makes it difficult for the power supply 6 to deteriorate, for example.

[0096] In the example of Fig. 13, under the control of the controller 51, in the operation period Pc1 of one cycle, the first light source unit 211 emits the excitation light L0 to the first wavelength conversion unit 321 in the first unit period P0, the third light source unit 213 emits the excitation light L0 to the third wavelength conversion unit 323 in the first to third unit periods P0, and the second light source unit 212 emits the excitation light L0 to the second wavelength conversion unit 322 in the sixth to tenth unit periods P0. According to the control of the example of Fig. 13, for example, in a state where the base material 31 is cooled during the longest possible non-emission period composed of two unit periods P0 between the third emission period including the first emission period and the second emission period, irradiation of the excitation light L0 to the second wavelength conversion unit 322 can be started. As a result, for example, the temperature of the second wavelength conversion unit 322 is unlikely to rise, and deterioration of the phosphor in the second wavelength conversion unit 322 can be reduced.

[0097] 14, under the control of the controller 51, in an operation period Pc1 of one cycle, the first light source unit 211 emits excitation light L0 to the first wavelength conversion unit 321 in the first unit period P0, the third light source unit 213 emits excitation light L0 to the third wavelength conversion unit 323 in the second to fourth unit periods P0, and the second light source unit 212 emits excitation light L0 to the second wavelength conversion unit 322 in the sixth to tenth unit periods P0. According to the control of the example of FIG. 14, for example, in the operation period Pc1 of one cycle, the first emission period, the third emission period, and the second emission period do not overlap each other, and a non-emission period consisting of one unit period P0 occurs between the third emission period and the second emission period. Thereby, for example, the temperatures of the first wavelength-converting section 321, the second wavelength-converting section 322, and the third wavelength-converting section 323 are unlikely to rise, and irradiation of the excitation light L0 to the second wavelength-converting section 322 can be started in a cooled state of the base material 31 after irradiation of the excitation light L0 to the third wavelength-converting section 323 is completed. As a result, for example, the temperature of the second wavelength-converting section 322 is unlikely to rise, and deterioration of the phosphor in the second wavelength-converting section 322 can be reduced.

[0098] In the example of Fig. 15, under the control of the controller 51, in the operation period Pc1 of one cycle, the first light source unit 211 emits the excitation light L0 to the first wavelength conversion unit 321 in the first to third unit periods P0, the third light source unit 213 emits the excitation light L0 to the third wavelength conversion unit 323 in the first to fifth unit periods P0, and the second light source unit 212 emits the excitation light L0 to the second wavelength conversion unit 322 in the fourth to tenth unit periods P0. According to the control of the example of Fig. 15, for example, in the operation period Pc1 of one cycle, the third emission period includes the first emission period, and no non-emission period occurs after the second emission period. As a result, for example, in the second emission period, the period during which the excitation light L0 is not irradiated to both the first wavelength conversion unit 321 and the third wavelength conversion unit 323 may become long. As a result, for example, the temperature of the second wavelength-converter 322 is less likely to increase, and deterioration of the phosphor in the second wavelength-converter 322 can be reduced.

[0099] 16, under the control of the controller 51, in the operation period Pc1 of one cycle, the first light source unit 211 emits the excitation light L0 to the first wavelength conversion unit 321 in the first to fifth unit periods P0, the third light source unit 213 emits the excitation light L0 to the third wavelength conversion unit 323 in the first to third unit periods P0, and the second light source unit 212 emits the excitation light L0 to the second wavelength conversion unit 322 in the tenth unit period P0. According to the control of the example of FIG. 16, for example, the second emission period does not overlap with either the first emission period or the third emission period, and irradiation of the excitation light L0 to the second wavelength conversion unit 322 can be started in a state where the base material 31 is well cooled in the longest possible non-emission period composed of four unit periods P0 between the first emission period and the second emission period including the third emission period. As a result, for example, the temperature of the second wavelength-converter 322 is less likely to increase, and deterioration of the phosphor in the second wavelength-converter 322 can be reduced.

[0100] 17, under the control of the controller 51, in an operation period Pc1 of one cycle, the first light source unit 211 emits excitation light L0 to the first wavelength conversion unit 321 in the first to fifth unit periods P0, the third light source unit 213 emits excitation light L0 to the third wavelength conversion unit 323 in the sixth to eighth unit periods P0, and the second light source unit 212 emits excitation light L0 to the second wavelength conversion unit 322 in the tenth unit period P0. According to the control of the example of FIG. 17, for example, in the operation period Pc1 of one cycle, the first emission period, the third emission period, and the second emission period do not overlap with each other, and a non-emission period consisting of one unit period P0 occurs between the third emission period and the second emission period. Thereby, for example, the temperatures of the first wavelength-converting section 321, the second wavelength-converting section 322, and the third wavelength-converting section 323 are unlikely to rise, and irradiation of the excitation light L0 to the second wavelength-converting section 322 can be started in a state in which the base material 31 is slightly cooled after irradiation of the excitation light L0 to the third wavelength-converting section 323 is completed. As a result, for example, the temperature of the second wavelength-converting section 322 is unlikely to rise, and deterioration of the phosphor in the second wavelength-converting section 322 can be reduced.

[0101] 18, under the control of the controller 51, in the operation period Pc1 of one cycle, the first light source unit 211 emits the excitation light L0 to the first wavelength conversion unit 321 in the first to seventh unit periods P0, the third light source unit 213 emits the excitation light L0 to the third wavelength conversion unit 323 in the first to fifth unit periods P0, and the second light source unit 212 emits the excitation light L0 to the second wavelength conversion unit 322 in the tenth unit period P0. According to the control of the example of FIG. 18, for example, the second emission period does not overlap with either the first emission period or the third emission period, and irradiation of the excitation light L0 to the second wavelength conversion unit 322 can be started in a state in which the base material 31 is cooled during the longest possible non-emission period composed of two unit periods P0 between the first emission period and the second emission period including the third emission period. As a result, for example, the temperature of the second wavelength-converter 322 is less likely to increase, and deterioration of the phosphor in the second wavelength-converter 322 can be reduced.

[0102] <2. Other embodiments> The present disclosure is not limited to the first embodiment described above, and various modifications are possible without departing from the gist of the present disclosure.

[0103] In the first embodiment, the first phosphor may be, for example, any of red, green, and blue phosphors. The second phosphor may be, for example, any of red, green, and blue phosphors that is different from the first phosphor. The third phosphor may be, for example, any of red, green, and blue phosphors that is different from the first and second phosphors.

[0104] In the first embodiment, for example, the first phosphor, the second phosphor, or the third phosphor may be a phosphor that emits fluorescence of various colors in response to irradiation with the excitation light L0, such as a blue-green phosphor or a yellow phosphor. The blue-green phosphor is a phosphor that emits blue-green fluorescence in response to irradiation with the excitation light L0. The yellow phosphor is a phosphor that emits yellow fluorescence in response to irradiation with the excitation light L0. For example, a phosphor that emits fluorescence with a peak wavelength in the range of about 495 nm in response to irradiation with the excitation light L0 is used as the blue-green phosphor. For example, (Sr,Ba,Ca)5(PO4)3Cl:Eu or Sr4Al is used as the material for the blue-green phosphor. 14 O 25 For example, SrSi2(O,Cl)2N2:Eu or the like is used. For example, a phosphor whose fluorescence wavelength peak is in the range of about 570 nm to 590 nm when irradiated with excitation light L0 is used as the yellow phosphor. For example, SrSi2(O,Cl)2N2:Eu or the like is used as the material for the yellow phosphor. Here, the ratio of the elements in parentheses can be set arbitrarily as long as it is within the range of the molecular formula.

[0105] In the first embodiment, for example, the plurality of light source units 21 may include two light source units 21. For example, a configuration is possible in which the plurality of light source units 21 include a first light source unit 211 and a second light source unit 212, the plurality of wavelength conversion units 32 include a first wavelength conversion unit 321 and a second wavelength conversion unit 322, and the plurality of driving units 52 include a first driving unit 521 and a second driving unit 522. FIG. 22 is a schematic diagram showing an example of the configuration of a lighting system 1A according to another first example. The lighting system 1A has a configuration in which the third driving unit 523, the third light source unit 213, and the third wavelength conversion unit 323 are deleted from the lighting system 1 according to the first embodiment.

[0106] Fig. 23 is a diagram showing a period during which each of the multiple light source units 21 emits the excitation light L0 in the lighting system 1A according to another first example. In Fig. 23, similar to Figs. 5 to 18, the horizontal axis indicates time, and the period during which each of the multiple light source units 21 emits the excitation light L0 is illustrated in three consecutive one-cycle operation periods Pc1 among many consecutive one-cycle operation periods Pc1. Also, in Fig. 23, similar to Figs. 5 to 18, the first emission period is indicated by a rectangle hatched with diagonal lines slanting upward to the right, and the second emission period is indicated by a rectangle hatched with sand.

[0107] 23, an operation period Pc1 of one cycle includes a first emission period in which the first light source unit 211 emits the excitation light L0 to the first wavelength conversion unit 321, and a second emission period in which the second light source unit 212 emits the excitation light L0 to the second wavelength conversion unit 322. Here, for example, when the controller 51 causes each of the multiple light source units 21 to repeatedly emit and not emit the excitation light L0 at a constant cycle, in the operation period Pc1 of one cycle, the controller 51 may not cause the second light source unit 212 to emit the excitation light L0 to the second wavelength conversion unit 322 during at least a part of the first emission period in which the first light source unit 211 emits the excitation light L0 to the first wavelength conversion unit 321. Further, for example, during an operating period Pc1 of one cycle, the controller 51 may not cause the first light source unit 211 to emit excitation light L0 to the first wavelength conversion unit 321 during at least a portion of the second emission period in which the second light source unit 212 emits excitation light L0 to the second wavelength conversion unit 322.

[0108] Even with such control, for example, the first emission period and the second emission period are shifted from each other in the operation period Pc1 of one cycle. This shortens the period during which the first wavelength conversion unit 321 and the second wavelength conversion unit 322 are heated simultaneously. As a result, for example, the temperatures of the first wavelength conversion unit 321 and the second wavelength conversion unit 322 are less likely to rise, and deterioration of the phosphors in the first wavelength conversion unit 321 and the second wavelength conversion unit 322 can be reduced. Therefore, for example, in the lighting system 1A capable of adjusting the color, deterioration of the phosphors can be reduced.

[0109] In the example of Fig. 23, under the control of the controller 51, in the operation period Pc1 of one cycle, the first light source unit 211 emits the excitation light L0 to the first wavelength conversion unit 321 in the first to fifth unit periods P0, and the second light source unit 212 emits the excitation light L0 to the second wavelength conversion unit 322 in the sixth to tenth unit periods P0. According to the control of the example of Fig. 23, for example, the first emission period and the second emission period do not overlap. As a result, for example, the temperatures of the first wavelength conversion unit 321 and the second wavelength conversion unit 322 are unlikely to rise, and deterioration of the phosphors in the first wavelength conversion unit 321 and the second wavelength conversion unit 322 can be reduced.

[0110] In the first embodiment, for example, the multiple light source units 21 may include any number of light source units 21 that is four or more. In other words, the multiple light source units 21 may include any number of light source units 21 that is two or more. In this case, the multiple wavelength conversion units 32 may include any number of wavelength conversion units 32 that is two or more. Also, the multiple drive units 52 may include any number of drive units 52 that is two or more.

[0111] 24 is a schematic diagram showing an example of the configuration of a lighting system 1B according to another second example. The lighting system 1B has a configuration in which a fourth light source section (also referred to as a fourth light source section) 214, a fourth wavelength conversion section (also referred to as a fourth wavelength conversion section) 324, and a fourth driving section (also referred to as a fourth driving section) 524 are added to the lighting system 1 according to the first embodiment. Here, the multiple light source sections 21 include a first light source section 211, a second light source section 212, a third light source section 213, and a fourth light source section 214. The multiple wavelength conversion sections 32 include a first wavelength conversion section 321, a second wavelength conversion section 322, a third wavelength conversion section 323, and a fourth wavelength conversion section 324. The fourth wavelength conversion unit 324 can emit fluorescence (also referred to as fourth fluorescence) L14 having a fourth wavelength spectrum different from any of the first wavelength spectrum, the second wavelength spectrum, and the third wavelength spectrum in response to irradiation with the excitation light L0 emitted from the fourth light source unit 214. The fourth wavelength conversion unit 324 includes, for example, a phosphor (also referred to as a fourth phosphor) that emits fluorescence of a fourth color in response to irradiation with the excitation light L0. Fluorescence of a color different from the first to third colors is applied to the fourth color fluorescence. For example, a phosphor that emits fluorescence of various colors in response to irradiation with the excitation light L0, such as a blue-green phosphor or a yellow phosphor, can be applied to the fourth phosphor. In addition, the multiple driving units 52 include a first driving unit 521, a second driving unit 522, a third driving unit 523, and a fourth driving unit 524. The fourth driving unit 524 can drive the fourth light source unit 214 in response to, for example, an instruction from the controller 51.

[0112] FIG. 25 is a diagram showing a period during which each of the multiple light source units 21 emits the excitation light L0 in the lighting system 1B according to another second example. In FIG. 25, as in FIG. 5 to FIG. 18, the horizontal axis indicates time, and the periods during which each of the multiple light source units 21 emits the excitation light L0 in three consecutive one-cycle operation periods Pc1 among many consecutive one-cycle operation periods Pc1 are illustrated. Also, in FIG. 25, as in FIG. 5 to FIG. 18, the first emission period is indicated by a rectangle hatched with diagonal lines that rise to the right, the third emission period is indicated by a rectangle hatched with diagonal lines that rise to the left, and the second emission period is indicated by a rectangle hatched with sand. Furthermore, in FIG. 25, a period during which the fourth light source unit 214 emits the excitation light L0 in one operation cycle period (also referred to as a fourth emission period) is indicated by a rectangle hatched with diagonal lines that rise to the right with wide intervals.

[0113] As shown in Fig. 25, the operation period Pc1 of one cycle includes a first emission period, a second emission period, a third emission period, and a fourth emission period. Here, for example, when the controller 51 causes each of the plurality of light source units 21 to repeatedly emit and not emit the excitation light L0 at a constant cycle, during the operation period Pc1 of one cycle, during at least a part of the first emission period during which the first light source unit 211 emits the excitation light L0 to the first wavelength conversion unit 321, the controller 51 may not cause the second light source unit 212 to emit the excitation light L0 to the second wavelength conversion unit 322. Also, for example, during the operation period Pc1 of one cycle, the controller 51 may not cause the first light source unit 211 to emit the excitation light L0 to the first wavelength conversion unit 321 during at least a part of the second emission period during which the second light source unit 212 emits the excitation light L0 to the second wavelength conversion unit 322.

[0114] Even with such control, for example, the first emission period and the second emission period are shifted from each other in the operation period Pc1 of one cycle. This shortens the period during which the first wavelength conversion unit 321 and the second wavelength conversion unit 322 are heated simultaneously. As a result, for example, the temperatures of the first wavelength conversion unit 321 and the second wavelength conversion unit 322 are less likely to rise, and deterioration of the phosphors in the first wavelength conversion unit 321 and the second wavelength conversion unit 322 can be reduced. Therefore, for example, in the lighting system 1B capable of adjusting the color, deterioration of the phosphors can be reduced.

[0115] 25, under the control of the controller 51, in an operation period Pc1 of one cycle, the first light source unit 211 emits excitation light L0 to the first wavelength conversion unit 321 and the third light source unit 213 emits excitation light L0 to the third wavelength conversion unit 323 in the first to fifth unit periods P0, and the second light source unit 212 emits excitation light L0 to the second wavelength conversion unit 322 and the fourth light source unit 214 emits excitation light L0 to the fourth wavelength conversion unit 324 in the sixth to tenth unit periods P0. According to the control in the example of FIG. 25, for example, the first emission period and the third emission period do not overlap with the second emission period and the fourth emission period. As a result, for example, the temperatures of the first wavelength conversion section 321, the second wavelength conversion section 322, the third wavelength conversion section 323 and the fourth wavelength conversion section 324 are less likely to rise, and deterioration of the phosphor in each of the first wavelength conversion section 321, the second wavelength conversion section 322, the third wavelength conversion section 323 and the fourth wavelength conversion section 324 can be reduced.

[0116] In the first embodiment, for example, each of the wavelength conversion sections 32 may contain a large number of particles of a plurality of types of phosphors. In this case, for example, the wavelength conversion sections 32 can be realized by varying the abundance ratio of the particles of the plurality of types of phosphors.

[0117] In the first embodiment, for example, as shown by the two-dot chain lines in FIG. 1, FIG. 22, and FIG. 24, the control device 5 may have a communication unit 53 capable of communicating with the external device 7. The communication unit 53 may also be a communication circuit. In this case, the controller 51 may acquire the program Pg1 or various data from the external device 7 by controlling the communication unit 53. The communication unit 53 may, for example, perform wireless communication with the external device 7 or may perform wired communication. The communication unit 53 may, for example, communicate with the external device 7 in accordance with USB (Universal Serial Bus), may communicate based on RFID (radio frequency identifier), may communicate in accordance with WiFi, or may communicate in accordance with other communication standards. The external device 7 may include, for example, a reading unit such as a drive or port to which a portable storage medium M0 in which the program Pg1 is stored can be attached or detached. For example, when the storage medium M0 is attached to the reading unit of the external device 7, the program Pg1 stored in the storage medium M0 may be read into the external device 7. Here, the storage medium M0, for example, stores the program Pg1 and serves as a computer-readable non-transitory storage medium. For example, an optical disk, a magnetic disk, or various non-volatile memories may be used as the storage medium M0.

[0118] In the first embodiment, for example, the light emitting unit 2 may be located apart from the conversion unit 3. In this case, for example, the excitation light L0 emitted from each of the multiple light source units 21 may be irradiated onto the corresponding wavelength conversion unit 32 via an optical transmission path such as an optical fiber.

[0119] In the first embodiment and each of the examples, for example, the lighting system 1, 1A, 1B may include a plurality of sets of a light-emitting unit 2, a conversion unit 3, and a light-guiding unit 4. In this case, for example, one control device 5 may control the driving of each light-emitting unit 2.

[0120] It goes without saying that all or part of the components constituting the first embodiment and the various examples described above can be appropriately combined to the extent that no contradiction occurs. [Explanation of symbols]

[0121] 1,1A,1B Lighting System 2 Light emitting unit 21 Light source section 211 1st light source section 212 Second light source section 213 Third light source section 214 4th light source section 3. Conversion section 31 Base material 32 Wavelength conversion section 321 First wavelength conversion unit 322 Second Wavelength Conversion Unit 323 Third Wavelength Converter 324 4th Wavelength Conversion Unit 4 Light guide section 5. Control device 51 Controller 511 CPU 512 Storage section 52 Drive unit 521 First Drive Unit 522 Second Drive Unit 523 3rd Drive Unit 524 4th Drive Unit 6 Power supply L0 excitation light L1 fluorescence L11 1st fluorescence L12 2nd fluorescence L13 3rd fluorescence L14 4th fluorescence L2 illumination light M0 storage medium P0 Unit Period Pc1 Operating period of one cycle Pg1 Program

Claims

1. a plurality of light source units each emitting an excitation light, the light source unit including a first light source unit and a second light source unit; A substrate; a plurality of wavelength conversion units located on the base material, the wavelength conversion units including a first wavelength conversion unit that emits fluorescence having a first wavelength spectrum in response to irradiation with excitation light emitted from the first light source unit, and a second wavelength conversion unit that emits fluorescence having a second wavelength spectrum different from the first wavelength spectrum in response to irradiation with excitation light emitted from the second light source unit; a light guiding unit that guides the fluorescence emitted by each of the plurality of wavelength conversion units; a controller that causes each of the plurality of light source units to repeatedly emit and not emit excitation light at a constant cycle; the controller, when causing each of the plurality of light source units to repeatedly emit and not emit excitation light at a constant cycle, during an operation period of one cycle from a first start timing at which the first light source unit starts a first irradiation of the first wavelength conversion unit with excitation light to a second start timing at which the first light source unit starts a second irradiation of the first wavelength conversion unit following the first irradiation of the excitation light, does not cause the second light source unit to emit excitation light to the second wavelength conversion unit during at least a portion of a first emission period in which the first light source unit emits excitation light to the first wavelength conversion unit, and does not cause the first light source unit to emit excitation light to the first wavelength conversion unit during at least a portion of a second emission period in which the second light source unit emits excitation light to the second wavelength conversion unit.

2. 2. A lighting system according to claim 1, the plurality of light source units includes a third light source unit that emits excitation light, the plurality of wavelength conversion units include a third wavelength conversion unit that emits fluorescence having a third wavelength spectrum different from both the first wavelength spectrum and the second wavelength spectrum in response to irradiation with excitation light emitted from the third light source unit, an operation period of the one cycle includes the first emission period, the second emission period, and a third emission period in which the third light source unit emits excitation light to the third wavelength conversion unit.

3. 3. A lighting system according to claim 2, the controller, during the operation period of one cycle, does not cause the third light source unit to emit excitation light to the third wavelength conversion unit during at least a portion of the first emission period, does not cause the first light source unit to emit excitation light to the first wavelength conversion unit during at least a portion of the third emission period, does not cause the third light source unit to emit excitation light to the third wavelength conversion unit during at least a portion of the second emission period, and does not cause the second light source unit to emit excitation light to the second wavelength conversion unit during at least a portion of the third emission period.

4. 4. A lighting system according to claim 3, the controller does not cause either the second light source unit or the third light source unit to emit excitation light to the second wavelength conversion unit and the third wavelength conversion unit during the first emission period, does not cause either the first light source unit or the second light source unit to emit excitation light to the first wavelength conversion unit and the second wavelength conversion unit during the third emission period, and does not cause either the first light source unit or the third light source unit to emit excitation light to the first wavelength conversion unit and the third wavelength conversion unit during the second emission period.

5. 5. A lighting system according to claim 4, the controller does not cause any of the first light source unit, the second light source unit, and the third light source unit to emit excitation light to the first wavelength conversion unit, the second wavelength conversion unit, and the third wavelength conversion unit, during a first non-emission period between the first emission period and the third emission period, a second non-emission period between the third emission period and the second emission period, and a third non-emission period after the second emission period, during each of the operation periods of the one cycle.

6. 6. A lighting system according to claim 5, The second non-emission period is longer than both the first non-emission period and the third non-emission period.

7. 5. A lighting system according to claim 4, the controller, during the operation period of the one cycle, does not generate a first non-emission period between the first emission period and the third emission period in which excitation light is not emitted to the first wavelength conversion unit, the second wavelength conversion unit, and the third wavelength conversion unit by any of the first light source unit, the second light source unit, and the third light source unit, and does not cause any of the first light source unit, the second light source unit, and the third light source unit to emit excitation light to the first wavelength conversion unit, the second wavelength conversion unit, and the third wavelength conversion unit in a second non-emission period between the third emission period and the second emission period, and in a third non-emission period after the second emission period, The second non-emitting period is longer than the third non-emitting period.

8. 3. A lighting system according to claim 2, an illumination system in which the controller does not cause either the first light source unit or the third light source unit to emit excitation light to the first wavelength conversion unit or the third wavelength conversion unit during at least a portion of the second emission period of the operation period of the one cycle.

9. 9. A lighting system according to claim 8, The controller causes the third light source unit to emit excitation light to the third wavelength conversion unit during at least a portion of the first emission period of the operation period of the one cycle.

10. 10. A lighting system according to claim 9, the controller, during the operation period of the one cycle, starts and ends emission of excitation light by the third light source unit to the third wavelength conversion unit in the first emission period, starts and ends emission of excitation light by the first light source unit to the first wavelength conversion unit in the third emission period, or simultaneously starts and ends emission of excitation light by each of the first light source unit and the third light source unit.

11. 11. A lighting system according to claim 10, the controller, during the operation period of the one cycle, does not generate a non-emission period after the second emission period in which no excitation light is emitted by any of the first light source unit, the second light source unit, or the third light source unit to the first wavelength conversion unit, the second wavelength conversion unit, or the third wavelength conversion unit.

12. 12. A lighting system according to claim 10 or 11, The controller, during the operation period of the one cycle, does not cause either the first light source unit or the third light source unit to emit excitation light to the first wavelength conversion unit and the third wavelength conversion unit during the second emission period.

13. 13. A lighting system according to claim 12, the controller, during the operation period of the one cycle, does not cause any of the first light source unit, the second light source unit, or the third light source unit to emit excitation light to the first wavelength conversion unit, the second wavelength conversion unit, and the third wavelength conversion unit in the first emission period and in a non-emission period between the third emission period and the second emission period.

14. A lighting system according to any one of claims 2 to 11, The illumination system, wherein in the one cycle operation period, the first emission period, the second emission period, and the third emission period have the same length.

15. A lighting system according to any one of claims 2 to 11, In the one cycle operation period, the first emission period, the second emission period, and the third emission period have lengths different from one another.

16. a plurality of wavelength conversion units located on the substrate, the plurality of wavelength conversion units including a first wavelength conversion unit that emits fluorescence having a first wavelength spectrum in response to irradiation with the excitation light emitted from the first light source unit and a second wavelength conversion unit that emits fluorescence having a second wavelength spectrum different from the first wavelength spectrum in response to irradiation with the excitation light emitted from the second light source unit; a light guiding unit that guides the fluorescence emitted by each of the plurality of wavelength conversion units; and a controller that controls emission and non-emission of excitation light from each of the plurality of light source units, (a) causing each of the plurality of light source units to repeatedly emit and not emit excitation light at a constant cycle by the controller; a control timing for controlling a lighting system, the control timing being set to a first start timing at which the first light source unit starts a first irradiation of the first wavelength conversion unit with excitation light to a second start timing at which the first light source unit starts a second irradiation of the first wavelength conversion unit following the first irradiation of the excitation light to the first wavelength conversion unit, the controller not causing the second light source unit to emit excitation light to the second wavelength conversion unit during at least a part of a first emission period in which the first light source unit emits excitation light to the first wavelength conversion unit, and not causing the first light source unit to emit excitation light to the first wavelength conversion unit during at least a part of a second emission period in which the second light source unit emits excitation light to the second wavelength conversion unit.

17. A method for controlling a lighting system according to claim 16, comprising the steps of: the plurality of light source units includes a third light source unit that emits excitation light, the plurality of wavelength conversion units include a third wavelength conversion unit that emits fluorescence having a third wavelength spectrum different from both the first wavelength spectrum and the second wavelength spectrum in response to irradiation with excitation light emitted from the third light source unit, A method for controlling an illumination system, wherein in the step (a), the controller causes the third light source unit to emit excitation light to the third wavelength conversion unit during the operation period of the one cycle.

18. a first wavelength conversion unit configured to emit fluorescence having a first wavelength spectrum in response to irradiation with the excitation light emitted from the first light source unit and a second wavelength conversion unit configured to emit fluorescence having a second wavelength spectrum different from the first wavelength spectrum in response to irradiation with the excitation light emitted from the second light source unit; a light guiding unit configured to guide the fluorescence emitted by each of the plurality of wavelength conversion units; and a controller configured to control emission and non-emission of excitation light from each of the plurality of light source units. The program is executed by the controller in an illumination system, causing the illumination system to function as the illumination system according to any one of claims 1 to 11.

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