lighting fixtures

Abstract

To provide a lighting fixture that can produce a change in the sky.SOLUTION: A lighting fixture comprises: an LED module for blue that emits light including a blue light component; a light guide plate that disperses the light from the LED module for blue and performs surface emission; and a lighting control unit that controls the lighting of the LED module for blue to reproduce the color of the sky based on a daylight line having a y value set higher than a black body locus in the CIE chromaticity coordinates and reproducing the color of the sky in the daytime, and a sunset line set to be an extension line of the black body locus in the CIE chromaticity coordinates and reproducing the sky of daybreak, evening, sunrise, or sunset. The lighting control unit controls the lighting of the LED module for blue so that an x value and the y value of the CIE chromaticity coordinates of the light dispersed from the light guide plate extend along the daylight line when reproducing the sky of the daytime, and controls the lighting of the LED module for blue so that the x value and the y value of the CIE chromaticity coordinates of the light dispersed from the light guide plate extend along the sunset line when reproducing the sky of daybreak, evening, sunrise, or sunset.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present disclosure relates to a lighting fixture equipped with an LED (Light Emitting Diode). [Background technology]

[0002] Conventionally, lighting fixtures capable of reproducing the appearance of the sky have been proposed. For example, the lighting fixture described in Patent Document 1 uses a light-emitting module having LEDs of multiple colors and controls the emission of blue light, yellow light, orange light, red light, and white light to reproduce the appearance of the sky. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-102166 Summary of the Invention [Problem to be solved by the invention]

[0004] The lighting fixture described in Patent Document 1 controls the emission of blue, yellow, orange, red, and white light to simulate natural skies such as blue skies, cloudy skies, evening skies, etc. However, the lighting fixture described in Patent Document 1 is not controlled in accordance with the actual changes in the sky, such as from blue daytime skies to evening or sunset.

[0005] The present disclosure is intended to solve the above-mentioned problems, and aims to provide a lighting device that can produce the illusion of a changing sky. [Means for solving the problem]

[0006] The lighting fixture according to the present disclosure comprises a blue LED module that emits light containing a blue light component; a light guide plate that diffuses the light from the blue LED module and emits it as a surface emission; and a dimming unit that reproduces the color of the sky by dimming the blue LED module based on a daylight line, which has a y value higher than the blackbody locus in the CIE chromaticity coordinates and reproduces the color of the daytime sky, and a sunset line, which is set to be an extension of the blackbody locus in the CIE chromaticity coordinates and reproduces the sky at dawn, dusk, sunrise, or sunset. When reproducing the sky at daytime, the dimming unit dims the blue LED module so that the x and y values ​​of the CIE chromaticity coordinates of the light diffused from the light guide plate follow the daylight line, and when reproducing the sky at dawn, dusk, sunrise, or sunset, the dimming unit dims the blue LED module so that the x and y values ​​of the CIE chromaticity coordinates of the light diffused from the light guide plate follow the sunset line. [Effects of the Invention]

[0007] According to the lighting fixture of the present disclosure, the dimming unit performs dimming based on the daylight line, which has a y value set higher than the blackbody locus to reproduce the color of the daytime sky, and the sunset line, which is set to be an extension of the blackbody locus to reproduce the sky at dawn, dusk, sunrise, or sunset, thereby improving the reproducibility of the sky color and making it possible to create the illusion of actual changes in the sky. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view showing the appearance of a lighting fixture according to a first embodiment. [Figure 2] 1 is an exploded perspective view showing the configuration of a lighting fixture according to a first embodiment. [Figure 3] 1 is an exploded perspective view showing the configuration of a light source unit of a lighting fixture according to Embodiment 1. FIG. [Figure 4] 1 is an exploded perspective view showing the configuration of a light source unit of a lighting fixture according to Embodiment 1. FIG. [Figure 5] 1 is a cross-sectional view showing a configuration of a lighting fixture according to a first embodiment. [Figure 6] 1 is a diagram showing a schematic configuration of a blue LED module according to a first embodiment. [Figure 7] 1 is a control block diagram of a lighting fixture according to Embodiment 1. FIG. [Figure 8] 4 is a graph showing the light intensity of the blue LED module according to the first embodiment. [Figure 9] 4 is a graph illustrating dimming control of the blue LED module according to the first embodiment. [Figure 10] 4 is a chromaticity diagram showing the chromaticity of light emitted from the light guide plate according to the first embodiment and the chromaticity of the actual sky as it changes. FIG. [Figure 11] 1 is a table showing the slopes and intercepts of the daylight line and sunset line in the CIE chromaticity coordinates according to the first embodiment. [Figure 12] 3 is a chromaticity diagram showing the allowable ranges of the daylight line and the sunset line according to the first embodiment. FIG. [Figure 13] 10 is a table showing the slopes and intercepts in the CIE chromaticity coordinates of the upper and lower limits of the allowable ranges of the daylight line and sunset line according to the first embodiment. [Figure 14] 10 is a table showing the width of the y value in the CIE chromaticity coordinates of the allowable range of the daylight line and sunset line according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of a lighting fixture will be described with reference to the drawings. The lighting fixture of the present disclosure is not limited to the following embodiments and can be modified in various ways. Furthermore, the lighting fixture of the present disclosure includes all possible combinations of the configurations shown in the following embodiments. In each drawing, identical reference numerals denote identical or equivalent components, and this applies throughout the specification. Throughout the specification, the vertical direction from the floor to the ceiling will be referred to as the "upper direction," and the ceiling side will be referred to as the "upper side." Similarly, the vertical direction from the ceiling to the floor will be referred to as the "downward direction," and the floor side will be referred to as the "lower side." Note that the relative dimensions or shapes of the components in each drawing may differ from those in actuality.

[0010] Embodiment 1 1 is a perspective view showing the appearance of lighting fixture 1 according to embodiment 1. Lighting fixture 1 is a ceiling-embedded lighting fixture, and includes fixture body 50 that is embedded in the ceiling, and light source unit 10 that is attached to fixture body 50. Light source unit 10 includes diffusion cover 13 that emits white light, and light guide plate 17 that emits blue light. Lighting fixture 1 can provide lighting with a visual effect that creates a sense of depth, like looking at the sky through a window frame, by using the blue light from light guide plate 17 and the white light from diffusion cover 13.

[0011] FIG. 2 is an exploded perspective view showing the configuration of lighting fixture 1 according to embodiment 1. Lighting fixture 1 is installed by being embedded in an embedding hole H provided in a ceiling C. As shown in FIG. 2, lighting fixture 1 has a fixture body 50 formed in the shape of a rectangular box, with an open bottom. Fixture body 50 has a main surface 51 and four side surfaces 52. Each of side surfaces 52 is provided to extend vertically downward from each of the four sides of main surface 51.

[0012] Of the four side surfaces 52 of the fixture body 50, V-spring mounting brackets 53 are attached to the inner surfaces of two opposing side surfaces 52. The V-spring mounting brackets 53 hook and hold V-springs 12 (described later) provided on the light source unit 10. Bolt holes 51-1 are provided at the four corners of the main surface 51. A hanging bolt B hangs from an embedded hole H in the ceiling C. The fixture body 50 is fixed to the ceiling C by inserting the hanging bolt B into the bolt hole 51-1 and then tightening the hanging bolt B with a nut 61.

[0013] Furthermore, the main surface 51 is formed with an electric wire hole 51-2 and is provided with a terminal block 54. The terminal block 54 has a power terminal block and a signal line terminal block. The power terminal block and the signal line terminal block are not shown in FIG. 2. Electric wires and signal lines are drawn out from the electric wire hole 51-2. The electric wires drawn out from the electric wire hole 51-2 are electrically connected to the power terminal block of the terminal block 54. Furthermore, the signal lines drawn out from the electric wire hole 51-2 are electrically connected to the signal line terminal block of the terminal block 54.

[0014] The light source unit 10 is disposed inside the opening of the fixture body 50. The light source unit 10 includes an upper cover 27, a flange portion 11, a V-spring 12, a diffusion cover 13, and a light guide plate 17. The upper cover 27 is formed in the shape of a truncated quadrangular pyramid with an open bottom end. Each of the four side surfaces of the upper cover 27 is formed in a trapezoidal shape, with the length of the upper side being shorter than the length of the lower side. The flange portion 11 is formed in the shape of a rectangular frame in a plan view. As shown in FIG. 2, the flange portion 11 is disposed so as to protrude horizontally outward from the bottom end of the upper cover 27.

[0015] The V springs 12 are wire springs formed by bending a metal wire into a V shape, and are attached to the upper surface of the flange portion 11. A total of four V springs 12 are provided, aligned with the positions of the V spring mounting brackets 53 of the fixture body 50. The V springs 12 engage with the V spring mounting brackets 53, thereby suspending and holding the light source unit 10 on the fixture body 50. When the lighting fixture 1 is attached to the recessed hole H in the ceiling C, the flange portion 11 covers the edge of the recessed hole H. Therefore, when the lighting fixture 1 is attached to the recessed hole H in the ceiling C, the recessed hole H is not visible to the user.

[0016] Figures 3 and 4 are exploded perspective views showing the configuration of light source unit 10 of lighting fixture 1 according to embodiment 1. Light source unit 10 is made up of the components shown in Figure 3 and the components shown in Figure 4. Figure 3 shows the components provided in the lower part of light source unit 10, and Figure 4 shows the components provided in the upper part of light source unit 10.

[0017] Among the components of the light source unit 10, the components shown in Fig. 3 will be described first. As shown in Fig. 3, the light source unit 10 includes a flange portion 11, a V-shaped spring 12, a packing 21, a diffusion cover 13, a packing 22, a white LED module 14, and a module holder 15.

[0018] As described above, the flange portion 11 is formed in the shape of a rectangular frame. The flange portion 11 is made of, for example, metal. A total of four V-springs 12 are provided on the upper surface of the flange portion 11.

[0019] The module holding part 15 is formed in the shape of a rectangular frame in a plan view. The module holding part 15 is configured by combining four members. As shown in FIG. 5, which will be described later, each of the four members has an L-shaped cross section. Also, as shown in FIG. 3, a mounting flange 15-1 is provided at the lower end of each of the four members of the module holding part 15. The mounting flange 15-1 is attached to the flange part 11 with screws.

[0020] The white LED module 14 has three substrates 140 and two types of white LEDs 141 and 142 with different color temperatures provided inside each of the three substrates 140. The three substrates 140 of the white LED module 14 are arranged in a U-shape in plan view, forming three sides of a rectangle. The angle between adjacent substrates 140 is 90°. The white LED module 14 emits white light from the three directions that make up the U-shape.

[0021] The white LEDs 141 are, for example, daylight LEDs with a color temperature of 4000 to 5000 (K), and the white LEDs 142 are, for example, warm white LEDs with a color temperature of 2600 to 3000 (K). The white LED module 14 can emit white light of various color temperatures and various light intensities by changing the dimming rate of the white LEDs 141 and 142. The white LEDs 141 and 142 may also be dimmed according to the time of day. For example, the white LEDs 141 and 142 are dimmed so that the light output is 100% during the day, 50% at dawn and dusk, and 20% at night. The white LEDs 141 and 142 are dimmed so that the light output is, for example, daylight white with a color temperature of 4500 K during the day, warm white with a color temperature of 3000 to 3500 K in the dusk, and 4000 to 3800 K at night.

[0022] Note that a light-emitting element or light-emitting device other than an LED may be used as the light source of the white LED module 14. The white LED module 14 may include only one type of white LED, or may include three or more types of white LEDs. The white LED module 14 is disposed inside the module holder 15 and is held by the module holder 15.

[0023] The packing 22 is formed in the shape of a thin rectangular frame in a plan view. The packing 22 is disposed between the upper end face of the diffusion cover 13 and the lower surface, which is the emission surface of the light guide plate 17 shown in FIG. 4. The packing 22 blocks light emitted from the blue LED module 18 (described later) from entering the upper end face of the diffusion cover 13 from the emission surface of the light guide plate 17. The packing 22 also blocks white light emitted from the white LED module 14 from entering the emission surface of the light guide plate 17 from the upper end face of the diffusion cover 13. The packing 22 also functions as a cushioning material when the lighting fixture 1 is shaken by an earthquake or the like.

[0024] The diffusion cover 13 is made of, for example, white resin and is formed into a rectangular frame shape in a plan view. The diffusion cover 13 has a quadrangular truncated pyramid shape with open top and bottom sides. That is, each of the four side surfaces of the diffusion cover 13 is inclined at a predetermined angle with respect to the vertical direction. Each of the four side surfaces of the diffusion cover 13 is made of a trapezoidal diffusion plate, and the length of the upper edge is shorter than the length of the lower edge. Furthermore, since each of the four side surfaces of the diffusion cover 13 is inclined, the position of the upper edge is positioned more inward than the position of the lower edge in a plan view. As a result, the internal space of the diffusion cover 13 tapers downward. The diffusion cover 13 may be formed by combining four trapezoidal diffusion plates or may be formed by integral molding.

[0025] Of the four side surfaces of the diffusion cover 13, three surfaces are light-emitting surfaces 13-1 and the remaining surface is a non-light-emitting surface 13-2. The three light-emitting surfaces 13-1 are arranged in a U-shape. Here, of each of the four side surfaces of the diffusion cover 13, the inner surface facing the internal space of the diffusion cover 13 is called the front surface, and the outer surface is called the back surface.

[0026] The diffusion cover 13 is disposed inside the white LED modules 14. That is, the white LED modules 14 are disposed on the back side of each of the light-emitting surfaces 13-1 of the diffusion cover 13. The white light emitted from the white LED modules 14 enters from the back side of the light-emitting surface 13-1 of the diffusion cover 13, passes through the light-emitting surface 13-1, and is emitted from the front side of the light-emitting surface 13-1. Because each of the light-emitting surfaces 13-1 is inclined, the white light emitted from the front sides of the three light-emitting surfaces 13-1 irradiates in a diagonally downward direction.

[0027] A light-shielding sheet (not shown) is attached to the back surface of the non-light-emitting surface 13-2 of the diffusion cover 13, so as to prevent light from leaking from the non-light-emitting surface 13-2.

[0028] In this way, the diffusion cover 13 has a configuration in which three light-emitting surfaces 13-1 that emit white light and one non-light-emitting surface 13-2 that does not emit light are combined. As a result, the light emitted from the diffusion cover 13 comes from three directions, creating a visual effect with a sense of depth, as if light from outside is shining through a window frame in the sunlight or a window frame in the shade.

[0029] The diffusion cover 13 is placed on the flange portion 11 via a packing 21. The packing 21 is formed in a thin rectangular frame shape in a plan view. The packing 21 prevents the flange portion 11 and the diffusion cover 13 from directly colliding with each other when they vibrate. The elasticity of the packing 21 also reduces the force applied from the flange portion 11 to the diffusion cover 13, thereby preventing damage to the diffusion cover 13. Furthermore, by providing the packing 21 between the flange portion 11 and the diffusion cover 13, the impression of a window frame can be created. This impression can be particularly enhanced when the packing 21 is a whitish color. The packing 21 also functions as a light-blocking section that prevents white light from leaking through the gap between the diffusion cover 13 and the flange portion 11.

[0030] Next, the components of the light source unit 10, those shown in Fig. 4, will be described. As shown in Fig. 4, the light source unit 10 further includes a lower guide plate 16, a light guide plate 17, a blue LED module 18, an upper guide plate 19, an insulating section 23, a module holding section 24, a fixing member 25, a light guide plate cover 26, and an upper cover 27. The light source unit 10 also includes a power supply device 31 and a dimming unit 32 disposed on the upper surface of the upper cover 27.

[0031] The lower guide plate 16 is placed on the module holder 15 shown in FIG. 3. The lower guide plate 16 is composed of two rod-shaped members and is arranged below the light guide plate 17, along the ends of the light guide plate 17 extending in the longitudinal direction. Protrusions 16-3 are provided on both ends of the two rod-shaped members that make up the lower guide plate 16. The protrusions 16-3 extend vertically upward. The protrusions 16-3 come into contact with an end face 17-2 extending in the lateral direction of the light guide plate 17, and restrict movement of the light guide plate 17 in the longitudinal direction.

[0032] The upper guide plate 19 is placed on the light guide plate 17. The upper guide plate 19 is made up of two rod-shaped members, and is disposed along the end of the light guide plate 17 extending in the longitudinal direction.

[0033] The light guide plate 17 is formed into a rectangular plate shape in a plan view. The light guide plate 17 diffuses the light emitted from the blue LED module 18 and emits blue light from the lower surface, which is the emission surface. The light guide plate 17 is made of acrylic resin and contains, for example, silica as a scatterer, which is a particle that scatters light. The longitudinal ends of the light guide plate 17 are sandwiched from above and below between the lower guide plate 16 and the upper guide plate 19.

[0034] The upper surface of light guide plate 17 is smooth to allow for total reflection. The upper surface of light guide plate 17 is preferably mirror-finished. If the upper surface of light guide plate 17 is scratched during the assembly of lighting fixture 1, total reflection will be less likely to occur at the scratched area. As a result, a portion of the lower surface corresponding to the scratched area on the upper surface will appear whitish. Therefore, to prevent the upper surface of light guide plate 17 from being scratched, the upper surface of light guide plate 17 may be covered with a reflective sheet (not shown).

[0035] The blue LED module 18 is arranged so as to be parallel to an end face 17-1 extending in the longitudinal direction of the light guide plate 17. The blue LED module 18 includes two substrates 180 and a plurality of LEDs arranged on each substrate 180. A plurality of through holes 18-1 are formed in the upper part of the substrate 180. The configuration and dimming control of the blue LED module 18 will be described in detail later.

[0036] The blue LED module 18 is attached to the module holding portion 24 by a fixing member 25. Cylindrical protrusions 25-1 are provided on the surface of the fixing member 25 facing the blue LED module 18. The protrusions 25-1 are inserted into the through holes 18-1 in the substrate 180 of the blue LED module 18. With the protrusions 25-1 inserted into the through holes 18-1, the fixing member 25 is screwed to the module holding portion 24.

[0037] The module holder 24 is formed from a metal plate having an L-shaped cross section. The module holder 24 not only holds the substrate 180 of the blue LED module 18, but also functions as a heat sink that dissipates heat from the blue LED module 18 to the outside. The module holder 24 is attached to the upper surface of the module holder 15 shown in FIG. 3. The blue LED module 18 is attached to the module holder 24 via an insulating part 23. If the substrate 180 of the blue LED module 18 is not a double-sided substrate, the insulating part 23 may be omitted.

[0038] The light guide plate cover 26 is placed on the upper guide plate 19. The light guide plate cover 26 covers the light guide plate 17 from above to protect the light guide plate 17. The upper cover 27 covers the components of the light source unit 10 shown in Figures 3 and 4 to protect these components. A power supply unit 31 and a dimming unit 32 are placed on the upper surface of the upper cover 27.

[0039] The power supply device 31 supplies power to the blue LED module 18 and the white LED module 14. The dimming unit 32 dims the LEDs included in the blue LED module 18 and the white LED module 14. The power supply device 31 and the dimming unit 32 are electrically connected by wiring such as a jumper wiring. Furthermore, when the light source unit 10 is attached to the fixture body 50, the power supply device 31 and the dimming unit 32 are electrically connected to the power terminal block and the signal terminal block of the terminal block 54 of the fixture body 50.

[0040] Fig. 5 is a cross-sectional view showing the configuration of lighting fixture 1 according to embodiment 1. Fig. 5 shows a cross section of lighting fixture 1 taken at the center in the longitudinal direction along a plane parallel to one side surface in the lateral direction.

[0041] As shown in Fig. 5, the light source unit 10 is disposed within an opening at the lower end of the fixture body 50. A V-spring 12 is provided on the upper surface of a flange portion 11 of the light source unit 10. The V-spring 12 is held in a state in which it is hooked onto a V-spring mounting bracket 53 provided on the fixture body 50. This engages the light source unit 10 with the fixture body 50, and the light source unit 10 is held in the fixture body 50.

[0042] The white LED module 14 is held by a module holder 15 and is disposed on the back surface of the diffusion cover 13. The blue LED module 18 is held by a module holder 24 fixed to the upper surface of the module holder 15 and is disposed so as to face an end surface 17-1 of the light guide plate 17 across a gap 33. The diffusion cover 13 and the light guide plate 17 are disposed so as to intersect with each other. Specifically, the light guide plate 17 is disposed parallel to the ceiling C, and the diffusion cover 13 is disposed so as to extend obliquely downward from the light guide plate 17.

[0043] White light emitted from the white LED module 14 enters the back surface of the diffusion cover 13 and exits from the front surface of the light-emitting surface 13-1 of the diffusion cover 13. Because the light-emitting surface 13-1 is inclined, the white light emitted from the front surface of the light-emitting surface 13-1 illuminates diagonally downward. Furthermore, light emitted from the blue LED module 18 enters the end surface 17-1 of the light guide plate 17 and travels through the light guide plate 17 while being totally reflected by the upper and lower surfaces of the light guide plate 17. A portion of the light traveling through the light guide plate 17 hits the scatterers inside the light guide plate 17 and is diffused, and is emitted from the lower surface of the light guide plate 17.

[0044] Next, the configuration and dimming control of blue LED module 18 in this embodiment will be described. Fig. 6 is a diagram showing a schematic configuration of blue LED module 18 according to embodiment 1. Fig. 6 shows a schematic configuration of one substrate 180 in blue LED module 18, but the configuration of the other substrate 180 is the same as that shown in Fig. 6. As shown in Fig. 6, a plurality of white LEDs 181, blue LEDs 182, and green LEDs 183 are arranged on substrate 180 of blue LED module 18. More specifically, a plurality of sets, each set consisting of two white LEDs 181, two blue LEDs 182, and one green LED 183, are arranged in a row on substrate 180.

[0045] The number and arrangement of the white LEDs 181, blue LEDs 182, and green LEDs 183 arranged on the substrate 180 of the blue LED module 18 are not limited to the example shown in FIG. 6 . For example, the white LEDs 181, blue LEDs 182, and green LEDs 183 may be arranged in a lower region of the substrate 180. In this case, the light guide plate 17 and the diffusion cover 13 can be arranged close to each other, allowing the blue light from the light guide plate 17 and the white light from the diffusion cover 13 to be emitted in close proximity. The white LEDs 181, blue LEDs 182, and green LEDs 183 may also be arranged with their positions offset in the vertical direction. The arrangement of the white LEDs 181, blue LEDs 182, and green LEDs 183 may be determined appropriately, taking into account color variations and the design of the substrate. However, to reproduce the color of the sky, it is desirable that the ratio of the number of white LEDs 181, blue LEDs 182, and green LEDs 183 to the total number of LEDs in the blue LED module 18 be 2:2:1.

[0046] A plurality of through holes 18-1 are provided in the upper part of the substrate 180 of the blue LED module 18. The through hole 18-1 (not shown) provided in the central part of the substrate 180 is circular, and the other through holes 18-1 are oval and extend in the longitudinal direction. The substrate 180 of the blue LED module 18 thermally expands and contracts due to heat emitted from the white LED 181, blue LED 182, and green LED 183. Therefore, when the blue LED module 18 is fixed to the module holder 24, warping or distortion due to thermal expansion and contraction may occur in the substrate 180 of the blue LED module 18.

[0047] Therefore, in this embodiment, an elliptical through-hole 18-1 is provided in the substrate 180, and the protrusion 25-1 of the fixing member 25 can be inserted into the through-hole 18-1 with some play. This allows the protrusion 25-1 to move longitudinally within the elliptical through-hole 18-1 even when the substrate 180 of the blue LED module 18 thermally expands and contracts, thereby preventing the substrate 180 from warping or distorting.

[0048] The white LED 181 is an LED having, for example, a color temperature of 5000 (K) and a forward voltage of 6 V. The blue LED 182 is an LED having, for example, a dominant wavelength of 440 to 480 nm and a forward voltage of 3 V. The green LED 183 is an LED having, for example, a dominant wavelength of 510 to 570 nm and a forward voltage of 3 V. The white LED 181 has a higher forward voltage than the blue LED 182 and the green LED 183, and emits light brighter than the blue LED 182 and the green LED 183 when the same current flows through them. That is, the output balance of the LEDs in the blue LED module 18 is white LED 181 > blue LED 182 > green LED 183.

[0049] The blue LED module 18 of this embodiment reproduces the color of the sky, particularly the color of a blue sky, by controlling the light emission of the white LED 181, the blue LED 182, and the green LED 183. By using the three colors white, blue, and green in this way, it is possible to improve color rendering properties compared to using the three colors red, blue, and green.

[0050] FIG. 7 is a control block diagram of the lighting fixture 1 according to the first embodiment. As shown in FIG. 7, the power supply device 31 includes a first power supply device 31a, a second power supply device 31b, and a third power supply device 31c, which respectively supply current to the white LED 181, the blue LED 182, and the green LED 183 of the blue LED module 18. By providing a power supply device for each LED, two-dimensional control of the light emission color of the blue LED module 18 is possible, thereby reproducing a variety of blue skies. The power supply device 31 further includes a fourth power supply device 31d and a fifth power supply device 31e, which respectively supply current to the white LED 141 and the white LED 142 of the white LED module 14.

[0051] The dimming unit 32 includes a first control circuit 32a that transmits a first dimming signal to the first power supply device 31a and the second power supply device 31b, and a second control circuit 32b that transmits a second dimming signal to the third power supply device 31c. That is, the first control circuit 32a controls the light emission of the white LED 181 and the blue LED 182 of the blue LED module 18, and the second control circuit 32b controls the light emission of the green LED 183 of the blue LED module 18.

[0052] The dimming unit 32 further includes a third control circuit 32c that transmits a third dimming signal to the fourth power supply device 31d, and a fourth control circuit 32d that transmits a fourth dimming signal to the fifth power supply device 31e. Specifically, the third control circuit 32c controls the light emission of the white LED 141 of the white LED module 14, and the fourth control circuit 32d controls the light emission of the white LED 142 of the white LED module 14. The first to fourth control circuits 32a to 32d each have, for example, a timer (not shown) and control the first to fifth power supply devices 31a to 32e according to the time. The first to fourth control circuits 32a to 32d are configured by hardware such as a dedicated single circuit or composite circuit, a microcomputer or processor that executes a program stored in memory, or a combination of these.

[0053] As described above, in this embodiment, the first control circuit 32a performs the same control on both the white LEDs 181 and the blue LEDs 182 of the blue LED module 18. This simplifies lighting control and reduces the number of control circuits compared to when a control circuit is provided for each LED. In this embodiment, the number of control circuits can be reduced to four, making development of the lighting device 1 easier.

[0054] The first to fifth dimming signals are, for example, PWM (Pulse Width Modulation) signals, and the light intensity is changed according to the duty ratio of the PWM signal. The power supply device 31 controls the dimming of the blue LED module 18 and the white LED module 14 by changing the current flowing through each LED based on the PWM signal.

[0055] FIG. 8 is a graph showing the light intensity of the blue LED module 18 according to the first embodiment. The horizontal axis of FIG. 8 represents time, and the vertical axis represents the light intensity of the blue LED module 18. The blue LED module 18 of this embodiment changes its light intensity according to the time, similar to the white LED module 14. Specifically, as shown in FIG. 8, the light intensity during the daytime (e.g., from 8:00 to 16:00) is 100%, the light intensity during the early morning (e.g., from 6:00 to 8:00) and the evening (e.g., from 16:00 to 18:00) is 50%, and the light intensity during the night (e.g., from 18:00 to 6:00) is 20%. Note that the times shown in FIG. 8 are merely examples and are not limited to the example shown in FIG. 8 and may be set as appropriate. The light intensity at each time may also be changed according to the season. For example, in summer, the daytime period during which the light intensity of the blue LED module 18 is 100% may be longer than in winter. Furthermore, not only the light intensity but also the chromaticity of the blue LED module 18 may be changed according to the season.

[0056] Fig. 9 is a graph illustrating the dimming control of the blue LED module 18 according to embodiment 1. The horizontal axis of Fig. 9 represents time, and the vertical axis represents the duty ratio of the dimming signal. The solid line in Fig. 9 represents the first dimming signal output from the first control circuit 32a, and the dashed line represents the second dimming signal output from the second control circuit 32b. As shown in Fig. 9, the first control circuit 32a and the second control circuit 32b set the duty ratio of the first dimming signal and the second dimming signal to 1 during the daytime.

[0057] Then, in the evening (for example, 4:00 PM), the first control circuit 32a reduces the duty ratio of the first dimming signal to 0.2 at a preset first reduction rate. The second control circuit 32b reduces the duty ratio of the second dimming signal to 0.2 at a second reduction rate that is greater than the first reduction rate. As a result, the light intensity of the green LED 183 first decreases to 20%, and then the light intensity of the white LED 181 and the blue LED 182 also decreases to 20%.

[0058] At dawn, the opposite control to that in the evening is performed. Specifically, first, the first control circuit 32a increases the duty ratio of the first dimming signal to 1 at a preset first increase rate. After a predetermined time has passed (for example, at 6:00) since the first control circuit 32a increased the duty ratio, the second control circuit 32b increases the duty ratio of the second dimming signal to 1 at a second increase rate that is greater than the first increase rate.

[0059] By performing such control, the light intensity of the green LED 183 decreases first in the evening, followed by the white LED 181 and blue LED 182, thereby changing the light from the light guide plate 17 to a deep purplish blue, similar to natural light.

[0060] FIG. 10 is a chromaticity diagram showing the chromaticity of light emitted from light guide plate 17 according to embodiment 1 and the chromaticity of the actual sky as it changes. The chromaticity of the actual sky was measured from 9:00 a.m. to 4:40 p.m. on November 29, 2019, in the sky north of Ofuna, Kamakura City, Kanagawa Prefecture, and is indicated by squares and diamonds in FIG. 10. Also in FIG. 10, the squares represent the chromaticity of the sky at an angle of approximately 20 degrees from the horizontal plane, and the diamonds represent the chromaticity of the sky (celestial body) at an angle of approximately 70 degrees from the horizontal plane. Also in FIG. 10, the blackbody locus is indicated by a dashed line, and CIE daylight is indicated by a dashed line.

[0061] As shown in Figure 10, the chromaticity of the actual sky from 9:00 a.m. to 4:00 p.m. is a line parallel to the blackbody locus, and moves along a line with a larger y value than the blackbody locus and CIE daylight in the x-y coordinates of the CIE chromaticity diagram (hereinafter referred to as "CIE chromaticity coordinates"). Then, from 4:00 p.m. to sunset at 4:40 p.m., the chromaticity of the actual sky moves toward the blackbody locus. That is, the y value of the actual sky chromaticity in the CIE chromaticity coordinates is in the positive direction relative to the blackbody locus during the daytime, and becomes equivalent to the blackbody locus at sunset.

[0062] The circles in Fig. 10 indicate the chromaticity of the light emitted from the light guide plate 17 during the daytime (e.g., from 8:00 to 16:00). Furthermore, the crosses in Fig. 10 indicate the chromaticity of the light emitted from the light guide plate 17 during the time periods of dawn (e.g., from 6:00 to 8:00) and dusk (e.g., from 16:00 to 18:00), and the triangles indicate the chromaticity of the light emitted from the light guide plate 17 at sunrise or sunset (e.g., 6:00 or 18:00). In Fig. 10, the arrows indicate the transition of the light emitted from the light guide plate 17 from daytime to dusk to sunset. The transition of the light emitted from the light guide plate 17 between sunrise, dawn, and daytime is in the opposite direction to the arrows in Fig. 10.

[0063] As shown in Fig. 10, in this embodiment, the chromaticity of light emitted from light guide plate 17 during the daytime is set on daylight line L1, which is an extension of the actual movement of the sky from morning to evening. Furthermore, the chromaticity of light emitted from light guide plate 17 at dawn, dusk, sunrise, or sunset is set on sunset line L2, which is an extension of the blackbody locus. Sunset line L2 is a straight line that is a first-order approximation of the blackbody locus from ∞K to 20,000K on the CIE chromaticity coordinates. Daylight line L1 is a parallel line to sunset line L2.

[0064] That is, the dimming unit 32 of this embodiment dims the blue LED module 18 so that the chromaticity of the light emitted from the light guide plate 17 during the daytime is such that the y value of the CIE chromaticity coordinates is in the positive direction relative to the sunset line L2, i.e., the extension of the blackbody locus. The dimming unit 32 also dims the blue LED module 18 so that the chromaticity of the light emitted from the light guide plate 17 at dawn, dusk, sunrise, or sunset is equivalent to the sunset line L2, i.e., the extension of the blackbody locus. When the sky darkens from daytime to dusk and from dusk to sunset, the dimming unit 32 dims the blue LED module 18 so that the x and y values ​​of the CIE chromaticity coordinates do not move in the positive direction. This allows the light emitted by the blue LED module 18 to become a deeper blue.

[0065] FIG. 11 is a table showing the slopes and intercepts of the daylight line L1 and sunset line L2 in the CIE chromaticity coordinates according to the first embodiment. As shown in FIG. 11, the slope of the sunset line L2, which is a straight line that linearly approximates the blackbody locus from ∞K to 20,000K on the CIE chromaticity coordinates, is 1.422 and the intercept is −0.107. Because the daylight line L1 is parallel to the sunset line L2, the slope of the daylight line L1 is the same as the slope of the sunset line L2, 1.422. The difference between the intercepts of the daylight line L1 and the sunset line L2 is the difference between the y value of the CIE chromaticity coordinates of the actual sky from 9:00 AM to 4:00 PM shown in FIG. 10 and the y value of the blackbody locus. As shown in FIG. 11, the difference between the CIE y value of the actual sky from 9:00 AM to 4:00 PM, calculated from measurements, and the CIE y value of the blackbody locus is 0.023. Therefore, the intercept of the daylight line L1 is -0.084, which is obtained by adding 0.023 to the intercept of the sunset line L2.

[0066] In light of the above, the dimming unit 32 of this embodiment dims the blue LED module 18 so that the chromaticity of the light emitted from the light guide plate 17 during the daytime falls on the daylight line, which is a straight line with a slope of 1.422 and an intercept of -0.084 in the CIE chromaticity coordinates. Also, the dimming unit 32 of this embodiment dims the blue LED module 18 so that the chromaticity of the light emitted from the light guide plate 17 at dawn, dusk, sunrise, or sunset falls on the sunset line with a slope of 1.422 and an intercept of -0.107 in the CIE chromaticity coordinates.

[0067] Note that the daylight line L1 and sunset line L2 are not limited to the examples shown in Figures 10 and 11, and may have a range of slopes. Figure 12 is a chromaticity diagram showing the allowable ranges of the daylight line L1 and sunset line L2 according to embodiment 1. For the sunset line L2, the allowable range of slope is shown, starting from the ∞K of blackbody radiation. For the daylight line L1, the allowable range of slope is shown, starting from the point +0.023 in CIEy value from the ∞K of blackbody radiation.

[0068] 13 is a table showing the slopes and intercepts of the upper and lower limits of the tolerance ranges of the daylight line L1 and the sunset line L2 in CIE chromaticity coordinates according to embodiment 1. As shown in FIGS. 12 and 13, the upper limit line L11 of the tolerance range of the daylight line L1 has a slope of 1.235 and an intercept of −0.039. The lower limit line L12 of the tolerance range of the daylight line L1 has a slope of 1.585 and an intercept of −0.123. The upper limit line L21 of the tolerance range of the sunset line L2 has a slope of 1.235 and an intercept of −0.062. The lower limit line L22 of the tolerance range of the sunset line L2 has a slope of 1.585 and an intercept of −0.146. The tolerance ranges of the daylight line L1 and the sunset line L2 described above are merely examples and are set based on the tolerance of the user of the lighting fixture 1.

[0069] Fig. 14 is a table showing the range of y values ​​in the CIE chromaticity coordinates of the allowable ranges of the daylight line L1 and the sunset line L2 according to Embodiment 1. As shown in Fig. 14, the range of CIE y values ​​of the daylight line L1 is ±0.017, and the range of CIE y values ​​of the sunset line L2 is -0.014 to +0.006.

[0070] In light of the above, the dimming unit 32 of the present embodiment may dim the blue LED module 18 so that the chromaticity of the light emitted from the light guide plate 17 during the daytime falls within an acceptable range that includes the daylight line L1. The dimming unit 32 may also dim the blue LED module 18 so that the chromaticity of the light emitted from the light guide plate 17 at dawn, dusk, sunrise, or sunset falls within an acceptable range that includes the sunset line L2. In this case, the y-value range of the CIE chromaticity coordinates for the daylight line L1 is ±0.017 of the y-value of the daylight line L1, and the y-value range of the CIE chromaticity coordinates for the sunset line L2 is −0.014 to +0.006 of the y-value of the sunset line L2.

[0071] As described above, in lighting fixture 1 of the present embodiment, blue light that creates the color of the sky is emitted from light guide plate 17, which is arranged parallel to ceiling C, and white light is emitted from three directions surrounding light guide plate 17. This creates a visual effect with a sense of depth, as if looking at a blue sky in sunlight or through a window frame in the shade. Furthermore, by dimming blue LED module 18 as described above, it is possible to emit blue light whose chromaticity changes in the same way as the actual sky changes, thereby creating the illusion of a changing sky.

[0072] In lighting fixture 1 of the present embodiment, the influence of the structure surrounding blue LED module 18 is also taken into consideration, and the blue LED module is dimmed so that the actual light appears to represent the color of the sky. For example, if a white reflective sheet is provided on the back surface of light guide plate 17, and the light emitted by blue LED module 18 in the evening is darkened to match the color of the sky that is actually measured, the color of the reflective sheet will be visible, causing the light from lighting fixture 1 to appear whitish. Therefore, in lighting fixture 1 of the present embodiment, the chromaticity changes to resemble the transitions in the actual sky, but the chromaticity itself is adjusted to a chromaticity different from that of the actual sky, thereby improving the reproducibility of the sky color.

[0073] Although the first embodiment has been described assuming that the lighting fixture 1 is mounted on the ceiling C, the lighting fixture 1 may also be mounted on a room wall. In this case, the white LED module 14 is L-shaped in a plan view. Accordingly, of the four sides of the diffusion cover 13, two adjacent sides are light-emitting surfaces 13-1, and the other two are non-light-emitting surfaces 13-2. The other configurations are the same as those of the first embodiment. As a result, even when the lighting fixture 1 is mounted on a room wall, it is possible to create a visual effect similar to that of seeing a deep blue sky through a window frame in a sunny or shaded area, just as when the lighting fixture 1 is mounted on the ceiling C. The shape of the lighting fixture 1 is not limited to a rectangle and may be a square box.

[0074] In addition, in the first embodiment, the first to fifth power supply devices 31a to 31e are provided for each LED, but this is not limited to this. For example, a common power supply device may be used for the white LEDs 181 and the blue LEDs 182 of the blue LED module 18. This allows for a further reduction in the number of components, which in turn allows for cost reduction and a more compact lighting fixture 1.

[0075] Furthermore, the structure for holding the blue LED module 18 is not limited to the structure described in embodiment 1. Furthermore, the lighting device 1 may be configured to omit the white LED module 14 and include only the blue LED module 18 as a light source.

[0076] In the above-described embodiment, two-stage control is performed in which the light intensity of the green LED 183 is first reduced, and then the light intensity of the white LED 181 and the blue LED 182 is reduced. However, this is not limiting. For example, two-stage control may be performed in which the light intensity of the white LED 181 and the blue LED 182 is reduced, and then the light intensity of the green LED 183 is reduced. Furthermore, the control of the white LED 181, the blue LED 182, and the green LED 183 is not limited to the above-described control. Either one or both of the x and y values ​​in the CIE chromaticity coordinates may be changed to the negative or positive side depending on the target sky color.

[0077] In the above embodiment, the blue LED module 18 includes a plurality of white LEDs 181, blue LEDs 182, and green LEDs 183. However, the configuration is not limited to this, as long as the LEDs emit light containing a blue light component. For example, the blue LED module 18 may include any of the following LEDs (1) to (7). (1) Blue LED, white LED, green LED, and amber LED. (2) Light blue LED, green LED, and amber LED. (3) Light blue LED and green LED. (4) White LED (8000~7000K) and amber LED. (5) Light blue LED and amber LED. (6) Light blue LED only. (7) White LED (8000~7000K) only. [Explanation of symbols]

[0078] 1 lighting fixture, 10 light source unit, 11 flange portion, 13 diffusion cover, 13-1 light-emitting surface, 13-2 non-light-emitting surface, 14 white LED module, 15 module holding portion, 15-1 mounting flange, 16 lower guide plate, 16-3 protrusion portion, 17 light guide plate, 17-1 end face, 17-2 end face, 18 blue LED module, 18-1 through hole, 19 upper guide plate, 21 packing, 22 packing, 23 insulating portion, 24 module holding portion, 25 fixing member, 25-1 protrusion portion, 26 light guide plate cover, 27 upper cover, 31 power supply unit, 31a first power supply unit, 31b second power supply unit, 31c third power supply unit, 31d fourth power supply unit, 31e fifth power supply unit, 32 dimming unit, 32a first control circuit, 32b Second control circuit, 32c third control circuit, 32d fourth control circuit, 33 air gap, 50 fixture body, 51 main surface, 51-1 bolt hole, 51-2 wire hole, 52 side, 53 mounting bracket, 54 terminal block, 61 nut, 140 circuit board, 141 white LED, 142 white LED, 180 circuit board, 181 white LED, 182 blue LED, 183 green LED, B hanging bolt, C ceiling, H recessed hole, L1 daylight line, L11, L21 upper limit lines, L12, L22 lower limit lines, L2 sunset line.

Claims

1. a blue LED module that emits light containing a blue light component; a light guide plate that diffuses the light from the blue LED module and emits it as a surface light; a dimming unit that dims the blue LED module based on a daylight line, which is set to have a higher y value than the blackbody locus in the CIE chromaticity coordinates and reproduces the color of the daytime sky, and a sunset line, which is set to be an extension of the blackbody locus in the CIE chromaticity coordinates and reproduces the sky at dawn, dusk, sunrise, or sunset, to reproduce the color of the sky; The dimming unit comprises: dimming the blue LED module so that the x and y values ​​of the CIE chromaticity coordinates of the light diffused from the light guide plate are along the daylight line when reproducing the daytime sky; When reproducing the sky at dawn, dusk, sunrise, or sunset, the lighting fixture dims the blue LED module so that the x and y CIE chromaticity coordinates of the light diffused from the light guide plate are aligned with the sunset line.

2. 2. The lighting fixture according to claim 1, wherein the dimming unit dims the light so that the x and y values ​​of the light diffused from the light guide plate change from values ​​along the daylight line to values ​​along the sunset line when changing from a state reproducing the daytime sky to a state reproducing the dawn, dusk, sunrise, or sunset sky.

3. 3. The lighting fixture according to claim 1, wherein the dimming unit dims the x and y values ​​of the light diffused from the light guide plate so that they change from values ​​along the sunset line to values ​​along the daylight line when changing from a state reproducing the sky at dawn, dusk, sunrise, or sunset to a state reproducing the sky at daytime.

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