lighting equipment

Abstract

To provide a lighting device capable of reducing turquoise blue sorting requirements to improve a yield, and making chromaticity uniform.SOLUTION: A lighting device (100) comprises: a first light emitting element (12a) that emits first light belonging to a first chromaticity rank; a second light emitting element (12b) that emits second light belonging to a second chromaticity rank; and a light mixing unit (20) that mixes the first light and the second light and emits the mixed light to the outside as irradiation light, where the first chromaticity rank and the second chromaticity rank are different, and the irradiation light is included within a turquoise blue chromaticity range.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a lighting device. [Background technology]

[0002] Conventionally, lighting devices that emit light of various colors have been installed inside and outside vehicles for purposes such as illuminating objects, displaying information, and improving design. Energy-saving, high-brightness light-emitting diodes (LEDs) are also commonly used as light sources for these lighting devices. For example, white light is used for headlights, red light for taillights and stoplights, and amber light for turn signals.

[0003] Furthermore, in recent years, lighting devices that use organic electroluminescence (EL) to emit light containing turquoise blue have also been proposed (see, for example, Patent Document 1). In addition to organic EL, lighting devices that emit turquoise blue light also include those that combine light-emitting diodes with wavelength conversion materials. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 080132 Summary of the Invention [Problem to be solved by the invention]

[0005] However, it is known that the emission wavelength of light-emitting diodes changes depending on the temperature and current density. When the wavelength of the primary light emitted from the light-emitting diode changes, the amount of wavelength conversion to secondary light in the wavelength conversion member also changes, and the chromaticity of the light irradiated from the entire lighting device also changes.

[0006] Fig. 6 is a chromaticity diagram showing the chromaticity change in an example of a conventional lighting device that emits turquoise blue light. The horizontal axis in Fig. 6 represents chromaticity Cx, and the vertical axis represents chromaticity Cy. The area surrounded by the dashed line in the chromaticity diagram represents the chromaticity range of turquoise blue. The triangles in the chromaticity diagram represent the change in the chromaticity diagram when the value of the current flowing through the lighting device at a temperature of 25°C is changed. The chip size of the light-emitting diode is 1 mm 2 The following are used.

[0007] In the example shown in Figure 6, the current value ranges from 1.0 A to 0.35 A (current density 1.0 A / mm 2 from 0.35A / mm 2 ), the chromaticity (Cx, Cy) changes from (0.09, 0.38) to (0.08, 0.44). Figure 6 shows the case where the current value changes, but it is known that chromaticity also changes when the temperature changes. In particular, within the chromaticity range of turquoise blue, there tends to be a large change in chromaticity relative to changes in emission wavelength. Therefore, in order to emit turquoise blue light from a lighting device, it is necessary to select and use a light source with characteristics that will remain within the turquoise blue chromaticity range even when current or temperature changes occur in the usage environment.

[0008] Generally, selecting a lighting device with such a narrow characteristic range reduces yield and increases manufacturing costs. Furthermore, even when using lighting devices selected to meet the characteristic range, there will still be differences in chromaticity between the upper and lower limits of the turquoise blue chromaticity, so it is preferable to use a turquoise blue chromaticity that is as close to the center as possible to achieve uniform chromaticity.

[0009] Therefore, the present invention has been made in consideration of the above-mentioned conventional problems, and aims to provide a lighting device that can relax the selection requirements for turquoise blue color, thereby improving yield and achieving uniform chromaticity. [Means for solving the problem]

[0010] In order to solve the above problem, the lighting device of the present invention includes a first light-emitting element that emits first light belonging to a first chromaticity rank, a second light-emitting element that emits second light belonging to a second chromaticity rank, and a light mixing unit that mixes the first light and the second light and irradiates the mixed light to the outside as irradiation light, wherein the first chromaticity rank and the second chromaticity rank are different, and the irradiation light is included in a turquoise blue chromaticity range. The chromaticity of the first light emitting element and the chromaticity of the second light emitting element change in opposite directions with respect to a temperature change. It is characterized by:

[0011] In such an illumination device of the present invention, the first light belonging to the first chromaticity rank and the second light belonging to the second chromaticity rank are mixed in the light mixing section, and even if the first chromaticity rank and the second chromaticity rank are different, the irradiated light falls within the chromaticity range of turquoise blue. This makes it possible to relax the selection requirements for turquoise blue color, improve yield, and achieve uniform chromaticity.

[0012] In one aspect of the present invention, the first chromaticity rank and the second chromaticity rank include an overlapping chromaticity range that is a common chromaticity range.

[0013] In one aspect of the present invention, at least one of the first chromaticity rank and the second chromaticity rank also includes an external chromaticity range that is outside the chromaticity range of the turquoise blue.

[0015] In one embodiment of the present invention, the first light emitting element and the second light emitting element are different from each other. The wavelength conversion member is In one aspect of the present invention, the wavelength conversion member uses a material that increases and decreases the amount of secondary light when the wavelength of the primary light is shifted toward a longer wavelength.

[0016] In one embodiment of the present invention, the chromaticity range of the turquoise blue corresponds to a wavelength of 485 nm or more and 500 nm or less. [Effects of the Invention]

[0017] The present invention can provide a lighting device that can alleviate the selection requirements for turquoise blue color, improve yield, and achieve uniform chromaticity. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic plan view showing an example of the configuration of a light-emitting unit 10 used in an illumination device 100 according to a first embodiment. [Figure 2] 1 is an exploded view schematically illustrating an example of the configuration of an illumination device 100 according to a first embodiment. [Figure 3] 3 is a chromaticity diagram showing the relationship between the first light, the second light, and the irradiation light in the lighting device 100 according to the first embodiment. FIG. [Figure 4] 10 is a chromaticity diagram showing an example of a combination of the first chromaticity rank and the second chromaticity rank in the lighting device 100 according to a modified example of the first embodiment. FIG. [Figure 5] 5A and 5B are chromaticity diagrams illustrating the temperature characteristics of the first light and the second light in the lighting device 100 according to the second embodiment, where FIG. 5A shows a case where the wavelength shortens with increasing temperature, and FIG. 5B shows a case where the wavelength lengthens with increasing temperature. [Figure 6] FIG. 1 is a chromaticity diagram showing chromaticity changes in an example of a conventional lighting device that emits turquoise blue light. DETAILED DESCRIPTION OF THE INVENTION

[0019] (First embodiment) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or equivalent components, members, and processes shown in each drawing will be assigned the same reference numerals, and redundant explanations will be omitted where appropriate. FIG. 1 is a schematic plan view showing an example of the configuration of a light-emitting unit 10 used in a lighting device 100 according to this embodiment. The light-emitting unit 10 is a part of the lighting device 100 that emits light. As shown in FIG. 1, the light-emitting unit 10 includes a mounting portion 11, light-emitting elements 12a and 12b, and an electronic component 13.

[0020] The mounting portion 11 is a member on which a wiring pattern (not shown) is formed and on which the light emitting elements 12a, 12b and the electronic components 13 are mounted. The configuration of the mounting portion 11 is not limited, and known materials and structures such as a normal printed wiring board, a ceramic board, a resin board, etc. can be used.

[0021] Light-emitting elements 12a and 12b are optical components mounted on mounting portion 11 and emit light at a predetermined wavelength when power is supplied, and correspond to the first and second light-emitting elements of the present invention. The first light and second light emitted by light-emitting elements 12a and 12b belong to a first chromaticity rank and a second chromaticity rank, respectively. As will be described later, the first light and second light emitted by light-emitting elements 12a and 12b are mixed in light mixing portion 20 to form irradiation light, which belongs to the chromaticity range of turquoise blue chromaticity.

[0022] The configuration of the light-emitting elements 12a and 12b is not limited, but an LED package combining a light-emitting diode (LED) that emits primary light and a wavelength conversion member that converts the wavelength of part of the primary light into secondary light can be used. The material of the light-emitting diode is also not limited, and known materials and structures can be used. For example, a GaN-based LED that emits blue light can be used. The material of the wavelength conversion member is also not limited. In the light-emitting elements 12a and 12b, part of the primary light emitted by the light-emitting diode is converted into secondary light by the wavelength conversion member, and the remaining unconverted primary light and secondary light irradiate first light belonging to a first chromaticity rank or second light belonging to a second chromaticity rank. The light-emitting elements 12a and 12b may each include a different wavelength conversion member, so that the chromaticity change characteristics due to temperature changes or current changes are different. The size of the light-emitting elements 12a and 12b is not limited, but for example, a chip size of 1 mm can be used. 2 can be used.

[0023] The electronic component 13 is a component that is mounted on the mounting portion 11 and performs a predetermined operation when power is supplied. The type of electronic component 13 may be a known resistor, diode, transistor, coil, IC (Integrated Circuit), etc. A circuit for driving the light-emitting elements 12a and 12b is configured by the wiring pattern provided on the mounting portion 11, the light-emitting elements 12a and 12b, and the electronic component 13.

[0024] Fig. 2 is an exploded view schematically illustrating an example of the configuration of an illumination device 100 according to this embodiment. As shown in Fig. 2, the illumination device 100 is configured by combining a light-emitting unit 10 and a light mixing unit 20. The light mixing unit 20 mixes first light and second light from light-emitting elements 12a and 12b included in the light-emitting unit 10, and irradiates the mixed light to the outside as illumination light. In the example shown in Fig. 2, the light mixing unit 20 is configured by combining a reflector 21, a light-guiding member 22, and a light diffusing member 23.

[0025] The reflector 21 is an optical member disposed behind the light-guiding member 22 and reflects at least a portion of the light emitted from the light-guiding member 22 on its reflective surface. The light reflected by the reflector 21 is emitted toward the outside of the lighting device 100 via the light-guiding member 22 and the light-diffusing member 23. The material constituting the reflector 21 is not limited, but a conventionally known resin material or the like can be used, and one coated with a highly reflective coating on the surface can be used. Here, an example is shown in which the reflector 21 and the light-guiding member 22 are configured as separate bodies, but the reflector 21 may be omitted by forming a highly reflective film or the like on the side surface of the light-guiding member 22.

[0026] The light-guiding member 22 is an optical member made of a light-transmitting material, which guides light along the extension direction and irradiates the guided light from the side. A light incident portion is provided at one end of the light-guiding member 22, and the light-emitting portion 10 is disposed opposite the light incident portion. The light-guiding member 22 has uneven steps formed along its side, and light guided inside is reflected by the uneven steps and irradiated from the side to the outside of the light-guiding member 22. In the example shown in FIG. 2, a substantially cylindrical light pipe is shown as the light-guiding member 22, but the light-guiding member 22 may be plate-shaped, and the specific shape is not limited.

[0027] The light diffusing member 23 is disposed on the light exit surface side of the light guide member 22, and is made of a material that transmits at least a portion of light and diffuses the light. The material that constitutes the light diffusing member 23 is not limited, and known resin materials and glass materials can be used. The structure for diffusing light in the light diffusing member 23 is also not limited, and examples that can be used include a structure in which light scattering particles with different refractive indices are contained in a resin material, a structure in which the front or back surface of the light diffusing member 23 is roughened, and a structure in which the light diffusing member 23 is a diffusion lens.

[0028] In the lighting device 100 shown in FIGS. 1 and 2, when power is supplied to the light-emitting elements 12a and 12b of the light-emitting unit 10, the light-emitting elements 12a and 12b emit first and second light, respectively. The first and second lights emitted by the light-emitting unit 10 propagate longitudinally through the light-guiding member 22, with a portion reflected by the reflector 21 and another portion reflected by the uneven steps, and then enter the light-diffusing member 23 from the light-emitting slope. The light that enters the light-diffusing member 23 is diffused by the light-diffusing structure of the light-diffusing member 23 and irradiated to the outside as illumination light. The illumination light at this time is a mixture of the first and second lights due to reflections by the light-guiding member 22 and the reflector 21 and diffusion by the light-diffusing member 23, and falls within the chromaticity range of turquoise blue chromaticity.

[0029] Fig. 3 is a chromaticity diagram showing the relationship between the first light, the second light, and the irradiation light in the lighting device 100 according to this embodiment. In Fig. 3, the horizontal axis represents chromaticity Cx, and the vertical axis represents chromaticity Cy. Here, the chromaticity range of turquoise blue (Cx, Cy) is within a trapezoidal range bounded by four points: (0.012, 0.495), (0.200, 0.400), (0.200, 0.320), and (0.040, 0.320), and the wavelength is 485 nm or more and 500 nm or less.

[0030] In the chromaticity diagram, the trapezoidal area surrounded by the dashed line indicates the chromaticity range of the first chromaticity rank, and the trapezoidal area surrounded by the dashed line indicates the chromaticity range of the second chromaticity rank. The straight lines in the diagram indicate chromaticity changes with current or temperature changes, with the dashed line indicating the first light of the light-emitting element 12a, the dashed line indicating the second light of the light-emitting element 12b, and the solid line indicating the light emitted from the light mixing unit 20.

[0031] 3, the first chromaticity rank (Cx, Cy) is within a trapezoidal range bounded by the four points (0.012, 0.495), (0.200, 0.400), (0.200, 0.360), and (0.040, 0.360).The second chromaticity rank (Cx, Cy) is within a trapezoidal range bounded by the four points (0.012, 0.430), (0.200, 0.370), (0.200, 0.320), and (0.040, 0.320). Therefore, the first chromaticity rank and the second chromaticity rank have a common overlapping chromaticity range, which is a trapezoid shape surrounded by the four points (0.012, 0.430), (0.200, 0.370), (0.200, 0.360), and (0.040, 0.360).

[0032] Light-emitting element 12a has a characteristic in which its chromaticity changes within a range along the dashed line shown in FIG. 3 when the current value (current density) changes, and is therefore classified as belonging to the first chromaticity rank. Light-emitting element 12b has a characteristic in which its chromaticity changes within a range along the dashed line shown in FIG. 3 when the current value (current density) changes, and is therefore classified as belonging to the second chromaticity rank. Here, the ranking of light-emitting elements 12a and 12b when the current changes can be performed by placing light-emitting elements 12a and 12b inside an integrating sphere maintained at a constant temperature and measuring the chromaticity using a spectrometer when a pulsed current is supplied at different current values. Alternatively, light-emitting elements 12a and 12b may be ranked after being subjected to a characteristic test conducted by the manufacturer prior to shipment.

[0033] Because the irradiated light is a mixture of the first and second lights, when the light intensities are the same, the chromaticity is intermediate, and the chromaticity varies within the range indicated by the solid line in Figure 3. Therefore, the irradiated light is also included in the turquoise blue chromaticity range. Furthermore, because the chromaticity of the irradiated light is intermediate between the first and second lights, it is closer to the center of the turquoise blue chromaticity range than the first and second lights. While Figure 3 shows the change in chromaticity with changing current, a similar effect can be achieved with the change in chromaticity with changing temperature. The temperature ranking of light-emitting elements 12a and 12b can be achieved by placing light-emitting elements 12a and 12b inside an integrating sphere and measuring the chromaticity using a spectrometer when the same current is supplied at different temperatures.

[0034] As described above, in the lighting device 100 of this embodiment, the first light belonging to the first chromaticity rank and the second light belonging to the second chromaticity rank are mixed in the light mixing section 20, so that the irradiated light falls within the chromaticity range of turquoise blue even if the first chromaticity rank and the second chromaticity rank are different. This relaxes the selection requirements for turquoise blue, improving yield and making the chromaticity uniform.

[0035] (Modification of the first embodiment) 4 is a chromaticity diagram showing an example of a combination of the first chromaticity rank and the second chromaticity rank in the lighting device 100 according to this modification. In the first embodiment, the first chromaticity rank and the second chromaticity rank are both included in the chromaticity range of turquoise blue, but in this modification, at least one of the first chromaticity rank or the second chromaticity rank also includes an external chromaticity range that is outside the chromaticity range of turquoise blue.

[0036] In the example shown in Figure 4(a), the first chromaticity rank (Cx, Cy) is within the trapezoidal range bounded by the four points (0.063, 0.364), (0.200, 0.317), (0.200, 0.302), and (0.076, 0.280). Also, the second chromaticity rank (Cx, Cy) is within the trapezoidal range bounded by the four points (0.050, 0.430), (0.200, 0.327), (0.200, 0.312), and (0.068, 0.335).

[0037] In the example shown in Figure 4(b), the first chromaticity rank (Cx, Cy) is within the trapezoidal range bounded by the four points (0.057, 0.381), (0.194, 0.334), (0.194, 0.319), and (0.070, 0.297). Also, the second chromaticity rank (Cx, Cy) is within the trapezoidal range bounded by the four points (0.044, 0.447), (0.194, 0.344), (0.194, 0.329), and (0.062, 0.352).

[0038] In the example shown in Figure 4(c), the first chromaticity rank (Cx, Cy) is within the trapezoidal range bounded by the four points (0.053, 0.397), (0.200, 0.348), (0.200, 0.306), and (0.070, 0.283). Also, the second chromaticity rank (Cx, Cy) is within the trapezoidal range bounded by the four points (0.041, 0.485), (0.200, 0.376), (0.200, 0.334), and (0.060, 0.359).

[0039] In the example shown in Figure 4(d), the first chromaticity rank (Cx, Cy) is within a trapezoidal range bounded by the four points (0.047, 0.414), (0.195, 0.365), (0.195, 0.323), and (0.064, 0.300). Also, the second chromaticity rank (Cx, Cy) is within a trapezoidal range bounded by the four points (0.035, 0.502), (0.195, 0.393), (0.195, 0.351), and (0.054, 0.502).

[0040] In this modification, the first or second chromaticity rank includes an outer chromaticity range outside the turquoise blue chromaticity range. However, as shown in FIG. 3, the irradiated light is a mixture of the first and second lights, resulting in a chromaticity between the two. Therefore, even if one of the chromaticity ranks includes the outer chromaticity range, the irradiated light can still be within the turquoise blue chromaticity range. This relaxes the selection requirements for the turquoise blue color of light-emitting elements 12a and 12b, improving yield.

[0041] In particular, as shown in Figures 4(c) and (d), it is preferable to set the first and second chromaticity ranks at the upper and lower sides of the turquoise blue chromaticity range. More specifically, it is preferable that the overlapping chromaticity range includes a portion of the median line connecting the two points (0.200, 0.360) and (0.008, 0, 418) in the middle of Cy in the turquoise blue chromaticity range. Furthermore, it is preferable that the areas of the first and second chromaticity ranks that are not included in the overlapping chromaticity range are located above and below the median line.

[0042] (Second embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. 5. Descriptions that overlap with the first embodiment will be omitted. In the first embodiment, light-emitting elements 12a and 12b were used that exhibited the same tendency for chromaticity change in response to temperature and current changes, but in this embodiment, elements with a characteristic that chromaticity changes in opposite directions are used. FIG. 5 is a chromaticity diagram illustrating the temperature characteristics of the first light and the second light in the lighting device 100 according to this embodiment, where FIG. 5(a) shows a case where the wavelength shortens with increasing temperature, and FIG. 5(b) shows a case where the wavelength lengthens with increasing temperature. The light-emitting elements 12a and 12b have a chip size of 1 mm. 2 The measurement was carried out at a constant current value (current density).

[0043] As such, light-emitting elements 12a and 12b whose chromaticity change characteristics change in opposite directions can be made by using different wavelength conversion members, one of which increases and the other decreases the amount of secondary light when the wavelength of the primary light shifts toward longer wavelengths. In this case, the chromaticity change of the light emitted from light-emitting elements 12a and 12b can be in opposite directions due to the shift to longer wavelengths of the primary light and the increase or decrease in the secondary light. Alternatively, the types of light-emitting diodes included in light-emitting elements 12a and 12b can be different.

[0044] Assume that light-emitting elements 12a and 12b have the chromaticity change characteristics shown in Figures 5(a) and 5(b). When the temperature changes from 25°C to 100°C, the chromaticity of light-emitting element 12a changes from (0.168, 0.375) to (0.163, 0.275). Similarly, the chromaticity of light-emitting element 12b changes from (0.074, 0.400) to (0.081, 0.448). In other words, the chromaticities of light-emitting elements 12a and 12b change in the direction in which the chromaticity Cy decreases and increases with increasing temperature, respectively, resulting in chromaticity changes in opposite directions relative to the temperature change. Furthermore, in this embodiment, light-emitting elements 12a and 12b can be said to belong to different chromaticity ranks.

[0045] When the first and second lights are emitted at equal intensities from light-emitting elements 12a and 12b, which have opposite chromaticity changes with temperature, and the two lights are mixed in the light mixing unit 20 shown in Figure 2, the chromaticity of the irradiated light varies from (0.121, 0.388) to (0.122, 0.362), which is intermediate between the two lights. This irradiated light falls within the turquoise blue chromaticity range, and its chromaticity change is smaller than that of the first and second lights. While Figure 5 shows the change in chromaticity with temperature, a similar effect can be achieved with the change in chromaticity with current.

[0046] In the lighting device 100 of this embodiment, the first light belonging to the first chromaticity rank and the second light belonging to the second chromaticity rank are mixed in the light mixing unit 20, so that the irradiated light falls within the turquoise blue chromaticity range even if the first and second chromaticity ranks are different. Furthermore, because the chromaticity of the light-emitting elements 12a and 12b changes in opposite directions with temperature, the chromaticity change of the irradiated light resulting from the mixture of the two elements can be suppressed. This relaxes the selection requirements for the turquoise blue color, improving yield and achieving uniform chromaticity.

[0047] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0048] 100...Lighting equipment 10...Light emitting part 20...Light mixing section 11...Installation section 12a, 12b...light-emitting elements 13...Electronic components 21...Reflector 22...Light guide member 23...Light diffusion member

Claims

1. a first light-emitting element that emits first light belonging to a first chromaticity rank; a second light-emitting element that emits second light belonging to a second chromaticity rank; a light mixing unit that mixes the first light and the second light and irradiates the mixed light to the outside as irradiation light, the first chromaticity rank and the second chromaticity rank are different, and the irradiated light is within a turquoise blue chromaticity range; The lighting device is characterized in that the chromaticity of the first light-emitting element and the chromaticity of the second light-emitting element change in opposite directions with respect to a temperature change.

2. 10. The lighting device according to claim 1, The lighting device, wherein the first chromaticity rank and the second chromaticity rank include an overlapping chromaticity range that is a common chromaticity range.

3. 10. The lighting device according to claim 1, At least one of the first chromaticity rank and the second chromaticity rank also includes an external chromaticity range that is outside the chromaticity range of the turquoise blue.

4. 10. The lighting device according to claim 1, The lighting device, wherein the first light-emitting element and the second light-emitting element each include a different wavelength conversion member.

5. A lighting device according to claim 4, The wavelength conversion member is made of a material that increases and decreases the amount of secondary light when the wavelength of the primary light is changed toward a longer wavelength.

6. 6. The lighting device according to claim 1, The turquoise blue chromaticity range corresponds to a wavelength of 485 nm or more and 500 nm or less.

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