Lighting equipment

Abstract

To provide a lighting device capable of improving comfort of a user according to each environment where individual lighting devices are installed, without requiring composite configuration and control.SOLUTION: A lighting device 1 comprises: a light source unit 3; a light absorption unit 4 that receives light emitted from the light source unit 3, changes spectral distribution by absorbing light in a specific wavelength band among the incident light, and emits light with the changed spectral distribution; and an optical element 5 that receives the light emitted from the light absorption unit 4, and emits illumination light toward an illumination space.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to an illumination device that changes the color temperature (color tone) of illumination light. [Background technology]

[0002] Research has been conducted on the relationship between the temperature felt by humans (hereinafter referred to as sensible temperature) and vision, and it is known that the sensible temperature of humans is affected by the illumination light emitted from a lighting device. For example, it is known that when the color temperature of the illumination light is high, it takes on a bluish tone, and humans feel that it is cool, whereas when the color temperature of the illumination light is low, it takes on a reddish tone, and humans feel that it is warm.

[0003] Patent Document 1 discloses a lighting device that includes multiple light sources with different emission colors and a control means for controlling the emission intensity of each of the multiple light sources, and the control means changes the spectral distribution of the illumination light by adjusting the emission intensity of the multiple light sources based on calendar information and time information. Patent Document 2 discloses a light source control device and a lighting device that includes multiple light sources with different emission colors, a temperature sensor, and a humidity sensor, and can maintain or improve comfort by controlling the emission colors of the multiple light sources while simultaneously considering the temperature and humidity around the lighting device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-259639 A [Patent Document 1] JP 2009-230907 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the lighting device disclosed in Patent Document 1 is designed to adjust the light emission intensity of multiple light sources with different light emission colors based on calendar information and time information, so the illumination light does not necessarily have a spectral distribution suitable for each environment in which each lighting device is actually used. Also, the lighting device disclosed in Patent Document 2 is equipped with multiple light sources with different light emission colors, a temperature sensor, a humidity sensor, and a light source control device, which makes the device large in size and the configuration and control of the device complex.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide lighting devices that can improve user comfort in accordance with the respective environments in which the individual lighting devices are installed, without requiring complex configurations and controls. [Means for solving the problem]

[0007] The lighting device according to the present disclosure includes a light source unit and Absorbs water or moisture, a light absorbing section which receives light emitted from a light source section, changes the spectral distribution by absorbing light of a specific wavelength band from the received light, and emits light with the changed spectral distribution; and an optical element which receives the light emitted from the light absorbing section, and emits illumination light toward an illumination space. 、 Equipped with The specific wavelength band changes depending on the amount of moisture absorbed by the light absorbing portion. This is what we have in mind. Effect of the Invention

[0008] Since the present disclosure is equipped with the above-mentioned configuration, it is possible to provide lighting devices that improve user comfort according to the respective environments in which the individual lighting devices are installed, with a simple configuration, without requiring complex configuration and control. [Brief description of the drawings]

[0009] [Figure 1] 1 is a perspective view showing a schematic configuration of an illumination device according to a first embodiment. [Diagram 2] 1 is a schematic diagram showing a configuration of a main part of an illumination device according to a first embodiment. [Diagram 3] FIG. 4 is a schematic diagram illustrating the relationship between the light absorbing part and the relative humidity according to the first embodiment. [Figure 4] 5 is a diagram showing the relationship between the medium passing length and the relative humidity in the light absorbing section according to the first embodiment. FIG. [Diagram 5] FIG. 4 is a schematic diagram illustrating the relationship between a light absorbing part and temperature according to the first embodiment. [Figure 6] 5 is a diagram showing the relationship between the medium passing length and temperature in the light absorption section according to the first embodiment. FIG. [Figure 7] 10 is a schematic diagram showing a configuration of a main part of an illumination device according to a second embodiment. FIG. [Figure 8] 11 is a schematic diagram showing a configuration of a main part of an illumination device according to embodiment 3. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of a lighting device according to the present disclosure will be described with reference to the drawings. In the following description, the same or corresponding components are given the same reference numerals, and the description may be omitted. However, cases where the same reference numerals are accompanied by different letters such as "a" and "b" are not included in the scope of the present disclosure.

[0011] The lighting device according to the present disclosure is not limited to the embodiments described below, and can be modified in various ways without departing from the spirit of the present disclosure. The lighting device shown in the drawings is an example of an embodiment to which the present disclosure is applied, and the scope of application of the present disclosure is not limited by the lighting device shown in the drawings.

[0012] In each drawing, the relative dimensional relationship or shape of each component may differ from the actual one. In addition, in the following description, orientation, direction, or position may be indicated. These notations are used for convenience to facilitate understanding of the description, and do not limit the orientation, direction, or position of the lighting device or the components that constitute the lighting device.

[0013] Embodiment 1 <Lighting equipment configuration> The configuration of the lighting device 1 according to the first embodiment will be described with reference to Figs. 1 and 2. Fig. 1 is a perspective view seen from the side of the illumination space, showing a general configuration of the lighting device 1 according to the first embodiment. Fig. 2 is a schematic diagram showing a configuration of a main part of the lighting device 1 according to the first embodiment. Fig. 2(a) is a perspective view seen from the side of the illumination space, and Fig. 2(b) is a view of a cross section including the optical axis of the light-emitting element 30 and the thickness direction of the light irradiation section 5.

[0014] The lighting device 1 is used by being attached to a mounting portion 9 such as a ceiling, a wall, a wiring duct, a raceway, or a T-bar. The lighting device 1 illuminates an illumination space, which is a space used by people. The lighting device 1 can be installed and used in a space used by people in, for example, a building such as an office, a hospital, or a residence, or in a moving object such as a train, a ship, or an airplane.

[0015] The lighting device 1 includes a housing 2, a light source unit 3, a light absorption unit 4, and a light irradiation unit 5. The housing 2 is the main body of the lighting device 1, and holds the light source unit 3, the light absorption unit 4, and the light irradiation unit 5. Although not shown, the lighting device 1 includes a power supply unit that generates and outputs lighting power for turning on the light source unit 3, and wiring material and the like that is connected to at least the power supply unit and the light source unit 3 and supplies lighting power to the light source unit 3. The light absorption unit 4 is a light absorber that has the property of absorbing light in a specific wavelength band. Illumination light is irradiated from the light irradiation unit 5 toward the illumination space.

[0016] The light source unit 3 is a light source of the lighting device 1, and light L1 emitted from the light source unit 3 is incident on the light absorption unit 4. The light source unit 3 has a light emitting element 30 and a printed wiring board (hereinafter referred to as a board) 31. The light emitting element 30 is, for example, a packaged surface mounted device (hereinafter referred to as an SMD) type LED. The light source unit 3 is, for example, a long board 31 on which a plurality of light emitting elements 30 are arranged along the longitudinal direction of the board 31, and is mounted using a conductive connection member such as solder. The light emitting element 30 emits white, red, green, or blue light. The light emitting elements 30 arranged may each emit a different color.

[0017] Although not shown in the drawings, in accordance with a Net Zero Energy Building (ZEB), a Net Zero Energy House (ZEH), a Life Cycle Carbon Minus House (LCCMH), or the like, the light source unit 3 may be replaced with a configuration that guides external light (natural light such as sunlight) to the vicinity of the lighting device 1. In this case, the external light is guided using a light guide such as an optical fiber.

[0018] L1 emitted from the light emitting element 30 of the light source unit 3 becomes incident light that enters (enters) the light absorbing unit 4. A specific wavelength band of the incident light L1 is absorbed (Lp) as it passes through the light absorbing unit 4. The amount of light (light flux) or spectral distribution of the incident light L1 changes as a result of the specific wavelength band being absorbed, and the incident light L1 is emitted (exits) from the light absorbing unit 4 as exit light L2. The incident light L1 enters a light entrance unit (light entrance end) 40 of the light absorbing unit 4, and the exit light L2 exits from a light exit unit (light exit end) 41 of the light absorbing unit 4.

[0019] The amount of light absorbed and the wavelength band of the light absorbing unit 4 are determined according to the environment in which the light absorbing unit 4 of the lighting device 1 is installed. Specifically, the light absorbing unit 4 absorbs a large amount of band components (colors) on the long wavelength side (reddish) in the visible light band in a high temperature and high humidity environment, and the outgoing light L2 emitted from the light absorbing unit 4 has a smaller ratio of the amount of light of band components (colors) on the long wavelength side (reddish) in the visible light band and a larger ratio of the amount of light of band components (colors) on the short wavelength side (blueish) compared to the incident light L1 incident on the light absorbing unit 4. In other words, the outgoing light L2 emitted from the light absorbing unit 4 shows a different spectral distribution from the incident light L1 incident on the light absorbing unit 4 according to the environment in which the light absorbing unit 4 is installed. Furthermore, the light absorption unit 4 absorbs less light in the visible light band in a low temperature and low humidity environment, and the difference between the spectral distribution of the outgoing light L2 emitted from the light absorption unit 4 and the spectral distribution of the incident light L1 incident on the light absorption unit 4 tends to be smaller compared to a high temperature and high humidity environment. Note that the shape, dimensions, and position of the light absorption unit 4 relative to the light source unit 3 are desirably determined so that substantially the entire amount of the outgoing light L1 emitted from the light source unit 3 is incident on the light absorption unit 4.

[0020] In the first embodiment, the light emitting unit 5 is an optical element that emits light from the lighting device 1 to the illumination space, and has, for example, a substantially square plate shape. One surface on the illumination space side is an emission unit (emission surface) 51 from which the illumination light L3 is emitted toward the illumination space. In addition, one of the four end surfaces facing each other is an incidence unit (incident end) 50 into which the emission light L2 emitted from the light absorbing unit 4 is incident. Note that one of the four end surfaces may be the incidence unit (incident end) 50, or three or more end surfaces may be the incidence unit (incident end) 50.

[0021] The light irradiation unit 5 is formed, for example, using a resin material to which fine particles are added. The light incident from the entrance unit 50 is scattered in the volume inside the light irradiation unit 5 by the fine particles, and is irradiated toward the illumination space from the exit unit 51. The exit unit 51 may be surface-treated so that the illumination light L3 irradiated toward the illumination space is surface-scattered.

[0022] Although not shown, the other surface opposite to the exit portion (exit surface) 51 of the light irradiation unit 5 faces the side of the housing 2, and the other surface may be subjected to diffuse reflection, total reflection, or a treatment equivalent thereto. A reflecting mirror or the like may be disposed so as to face the other surface of the light irradiation unit 5. The light irradiation unit 5 is not limited to a substantially square shape including a square, and may be a polygonal shape having more than one side, or a substantially circular plate shape including a circle. The light irradiation unit 5 is not limited to the above-mentioned one, and may be changed according to the specifications of the lighting device 1. For example, the light irradiation unit 5 may be a shape other than a plate shape, and the light irradiation unit 5 may be another optical element having another optical function such as a lens or a reflector.

[0023] <About the light absorbing part> The light absorbing unit 4 according to the first embodiment and the relationship between the light absorbing unit 4 and the relative humidity will be described with reference to Figs. 3 and 4. Fig. 3 is a schematic diagram for explaining the relationship between the light absorbing unit 4 according to the first embodiment and the relative humidity. Fig. 3(a) shows the light absorbing unit 4 in a state where the relative humidity φ in the place where the lighting device 1 is installed is low (φl), Fig. 3(b) shows the light absorbing unit 4 in a state where the relative humidity φ in the place where the lighting device 1 is installed is standard (φm), and Fig. 3(c) shows the light absorbing unit 4 in a state where the relative humidity φ in the place where the lighting device 1 is installed is high (φh). Fig. 4 is a diagram showing the relationship between the medium passing length and the relative humidity in the light absorbing unit 4 according to the first embodiment.

[0024] The light absorbing section 4 is composed of a light absorbing medium 42 having a property of absorbing light in a specific wavelength band, and a storage section 43 in which the light absorbing medium 42 is stored. The storage section 43 has water absorption and hygroscopic properties. The storage section 43 is, for example, a porous body formed using a light-transmitting resin, and water molecules (water vapor) and the like are absorbed (adsorbed) into the pores 44. The light absorbing medium 42 is, for example, water molecules (water vapor) contained in the atmosphere, and is absorbed (adsorbed) into the pores 44 of the storage section 43 which is a porous body. The amount of moisture of the light absorbing medium 42 absorbed into the storage section 43 is affected by the environment such as humidity and temperature in the place where the lighting device 1 is installed, and depends on these environments. The porous body used as the storage section 43 may be formed using a synthetic resin or a resin derived from natural sources. The storage section 43 may also be a natural porous material itself.

[0025] The storage section 43 is a solid that transmits light. Preferably, the storage section 43 is a transparent solid. Here, "transparent" refers to a property of having a light transmittance of approximately 80% or more. The storage section 43 is a solid having a structure that allows moisture absorption and desorption, or a solid formed of a material having moisture absorption and desorption properties. The storage section 43 can be formed of a transparent resin material having properties such as thermoplasticity, thermosetting, and photopolymerization, and specifically, an acrylic polymer, an olefin polymer, a vinyl polymer, a cellulose polymer, an amide polymer, a fluorine polymer, a urethane polymer, a silicone polymer, or an imide polymer can be used.

[0026] The storage section 43 may be a gel (solidified body) that transmits light. Preferably, the storage section 43 is a transparent gel. Here, "transparent" refers to a property of having a light transmittance of approximately 80% or more. The storage section 43 is a gel having a structure that allows moisture absorption and release, or a gel made of a material that has moisture absorption and release properties. The storage section 43 is a gel that can maintain its shape and can be arranged between the light source section 3 and the light irradiation section 5, and specifically, polyacrylic acid gel, silicone gel, cellulose gel, polyurethane gel, polyolefin gel, gelatin, etc. can be used. The storage section 43 may also be formed of inorganic substances such as transparent glass and ceramics.

[0027] In general, the light absorption coefficient (absorption rate) of water varies depending on the wavelength band. The absorption coefficient of water in the wavelength band including visible light tends to be relatively small in the ultraviolet to blue wavelength band (so-called short wavelength band) and tends to be relatively large in the red to infrared wavelength band (so-called long wavelength band). This tendency does not depend on the type of light source, and is a common tendency to all light including LEDs used as the light emitting element 30 as well as natural light such as sunlight.

[0028] The amount of water molecules contained in the air corresponding to the relative humidity φ at the place where the lighting device 1 is installed is absorbed into the pores 44 of the porous body that is the storage section 43. That is, the amount of moisture that becomes the light absorbing medium 42 stored in the storage section 43 changes depending on the relative humidity φ of the space in which the light absorbing section 4 is placed. The moisture absorbed in the pores 44 acts as the light absorbing medium 42 for the light that is incident on the light absorbing section 4. The light L1 emitted from the light source section 3 is incident on the light absorbing section 4, and at least a part of the light Lp that is incident on the light absorbing section 4 passes through the moisture that is the light absorbing medium 42 absorbed in the pores 44 of the porous body that is the storage section 43. At this time, the light Lp that passes through the light absorbing medium 42 is affected by the light absorption characteristics of water, so that components in the red to infrared wavelength band are absorbed relatively more. For this reason, the emitted light L2 that passes through the light absorbing medium 42 and is emitted from the light absorbing section 4 has a bluish tone than the light L1 emitted from the light source section 3. In this way, when the lighting device 1 is installed in a location where the relative humidity φ is such that water is absorbed in the storage section 43 as the light-absorbing medium 42, the exiting light L2 having a spectral distribution different from the spectral distribution originally possessed by the incident light L1 emitted from the light source section 3 and entering the light-absorbing section 4 from the light-receiving section 40 is emitted from the light-exiting section 41.

[0029] The amount of components in the red to infrared wavelength band absorbed by the light-absorbing medium 42 depends on the distance P that the light Lp passing through the inside of the light-absorbing section 4 travels through the light-absorbing medium 42. As the optical path length P, which is the sum of the distances Pn that the light Lp passing through the inside of the light-absorbing section 4 travels through the light-absorbing medium 42, becomes longer, the amount of components in the red to infrared wavelength band absorbed increases, and as the optical path length P becomes shorter, the amount of components in the red to infrared wavelength band absorbed decreases.

[0030] In a state where the amount of water molecules contained in the air is large and the relative humidity φ is high (φh), the amount of moisture, which is the light absorption medium 42, absorbed (adsorbed) in the pores 44 of the porous body, which is the storage portion 43 in the light absorption portion 4, increases. As a result, the amount of components in the red to infrared wavelength band absorbed by the light absorption medium 42 increases in the light Lp passing through the inside of the light absorption portion 4, and the difference between the original spectral distribution of the incident light L1 incident on the light absorption portion 4 and the spectral distribution of the output light L2 output from the light absorption portion 4 becomes large. In other words, the output light L2 with a bluish tone is output from the light absorption portion 4.

[0031] In contrast, in a state (φl) in which the amount of water molecules contained in the air is small and the relative humidity φ is low, the amount of moisture, which is the light absorption medium 42, absorbed (adsorbed) in the pores 44 of the porous body, which is the storage section 43 in the light absorption section 4, decreases. For this reason, the amount of components in the red to infrared wavelength band absorbed by the light absorption medium 42 in the light Lp passing through the inside of the light absorption section 4 decreases, and the difference between the original spectral distribution of the incident light L1 incident on the light absorption section 4 and the spectral distribution of the output light L2 output from the light absorption section 4 becomes smaller. In other words, the output light L2 output from the light absorption section 4 does not have a bluish tone, or has a slightly bluish tone.

[0032] In this way, the light absorbing section 4 enables the lighting device 1 to obtain light with a color tone that directly reflects the humidity, which is the environment of the place where the lighting device 1 is installed.

[0033] The relationship between the light absorption unit 4 and temperature according to the first embodiment will be described with reference to Figs. 5 and 6. Fig. 5 is a schematic diagram for explaining the relationship between the light absorption unit 4 and temperature according to the first embodiment. Fig. 5(a) shows the light absorption unit 4 in a state where the temperature T at the location where the lighting device 1 is installed is low (Tl), and Fig. 5(b) shows the light absorption unit 4 in a state where the temperature T at the location where the lighting device 1 is installed is high (Th). Fig. 6 is a diagram showing the relationship between the medium passing length and temperature in the light absorption unit 4 according to the first embodiment.

[0034] For the accommodation section 43 of the light absorbing unit 4, a material having a positive expansion coefficient with respect to the environmental temperature T at the place where the lighting device 1 is installed can be selected. By forming the accommodation section 43 using a material with such properties, the accommodation section 43 expands as a whole as the environmental temperature T increases, and the volume of the pores 44 of the porous body that is the accommodation section 43 increases. Therefore, the amount of moisture that is the light absorbing medium 42 that can be absorbed in the pores 44 increases. Conversely, as the environmental temperature T decreases, the entire section contracts and the volume of the pores 44 of the porous body that is the accommodation section 43 decreases. Therefore, the amount of moisture that is the light absorbing medium 42 that can be absorbed in the pores 44 decreases.

[0035] When the environmental temperature T at the location where the lighting device 1 is installed is high (Th), the maximum capacity of the pores 44 of the porous body that is the storage section 43 in the light-absorbing section 4 increases, and the maximum amount of moisture that is the light-absorbing medium 42 that can be absorbed (adsorbed) in the pores 44 increases. For this reason, the amount of components in the red to infrared wavelength band that are absorbed by the light-absorbing medium 42 increases in the light Lp passing through the inside of the light-absorbing section 4, and the difference between the original spectral distribution of the incident light L1 that enters the light-absorbing section 4 and the spectral distribution of the output light L2 that is output from the light-absorbing section 4 becomes large. In other words, output light L2 with a bluish tone is output from the light-absorbing section 4.

[0036] In contrast, when the environmental temperature T at the location where the lighting device 1 is installed is low (Tl), the maximum capacity of the pores 44 of the porous body that is the storage section 43 in the light-absorbing section 4 decreases, and the maximum amount of moisture that is the light-absorbing medium 42 that can be absorbed (adsorbed) in the pores 44 decreases. For this reason, the amount of components in the red to infrared wavelength band absorbed by the light-absorbing medium 42 in the light Lp passing through the inside of the light-absorbing section 4 decreases, and the difference between the original spectral distribution of the incident light L1 that enters the light-absorbing section 4 and the spectral distribution of the output light L2 that is output from the light-absorbing section 4 becomes smaller. In other words, the output light L2 output from the light-absorbing section 4 does not have a bluish tone, or has a slightly bluish tone.

[0037] In this way, the light absorbing section 4 enables the lighting device 1 to obtain light with a color tone that directly reflects the temperature of the environment in which the lighting device 1 is installed.

[0038] <About the effects> The higher the humidity or temperature in the place where the lighting device 1 is installed, the more the lighting device 1 functions as cool lighting using bluish light with fewer components in the red to infrared wavelength bands, and is expected to have the effect of lowering the sensible temperature of people using the space illuminated by the lighting device 1 and providing a cool sensation to people using this space. Also, the lower the humidity or temperature in the place where the lighting device 1 is installed, the more the lighting device 1 as described above functions as warm lighting using light with a significant amount of components in the red to infrared wavelength bands (light that is almost not bluish), and is expected to have the effect of raising the sensible temperature of people using the space illuminated by the lighting device 1 and providing a warm sensation.

[0039] That is, the lighting device 1 can adjust the spectral distribution (color temperature) of the light source color to a spectral distribution (color temperature) suitable for the installation environment, such as the humidity or temperature of the place where the lighting device 1 is installed, by the light absorption unit 4. Furthermore, the lighting device 1 can change the spectral distribution (color temperature) of the light source color by the light absorption unit 4 so as to follow changes in the installation environment, such as the humidity or temperature of the place where the lighting device 1 is installed.

[0040] Furthermore, the lighting device 1 does not require a complex configuration such as multiple light sources with different light emission colors, a temperature sensor, a humidity sensor, and a light source control device, or a complex light source control procedure using calendar information, time information, etc., and is advantageous in that environmental conditions such as humidity and temperature of the location where the lighting device 1 is installed can be directly reflected in the light source color of the lighting device 1, allowing the lighting device 1 to be simplified overall.

[0041] <Other> In recent years, from the perspective of protecting the global environment and saving energy, there has been a demand for air-conditioning-controlled living spaces to be set at higher temperatures in the summer and lower temperatures in the winter, and companies and private homes have been making efforts to comply with this. However, these efforts also affect comfort, mental and physical health, and activity performance. It is meaningful to focus on the relationship between perceived temperature and vision and minimize such effects by using lighting emitted from lighting devices. This is also excellent from the perspective of the international Sustainable Development Goals (SDGs), and in particular contributes to issues such as energy sustainability and greenhouse gas emissions reduction into the future.

[0042] Embodiment 2 An illumination device 1a according to embodiment 2 will be described with reference to Fig. 7. Fig. 7 is a schematic diagram showing the configuration of the main parts of the illumination device 1a according to embodiment 2, and is a cross-sectional view including the optical axis of the light-emitting element 30 and the thickness direction of the light irradiation unit 5. In Fig. 7, the same reference numerals are used for parts corresponding to those in Fig. 2(b), and duplicated descriptions of corresponding parts with the same reference numerals may be omitted. The illumination device 1a differs from embodiment 1 in that it is provided with a light-absorbing unit 4a.

[0043] <About the light absorbing part> The light absorbing unit 4a is composed of a light absorbing medium 42a having a property of absorbing light in a specific wavelength band, and a storage unit 43a in which the light absorbing medium 42a is stored. The storage unit 43a is, for example, a container body formed in a box shape using a light-transmitting resin, and has water-stopping and moisture-permeable properties. The light absorbing medium 42a stored in the storage unit 43a is an absorber (adsorbent) capable of absorbing and releasing water molecules (water vapor) contained in the air. The amount of moisture absorbed by the light absorbing medium 42a is determined by the humidity, temperature, etc. of the place where the lighting device 1a is installed.

[0044] The storage unit 43a, which is a container body, has a light-transmitting light entrance unit (light entrance end) 40a into which the light L1 emitted from the light source unit 3 enters, and a light-transmitting light exit unit (light exit end) 41a from which the light Lp passing through the light absorption unit 4a is emitted. The optical path length P of the light Lp passing through the light absorption medium 42a filled in the storage unit 43a can be determined by the size and shape of the storage unit 43a.

[0045] The storage section 43a is a solid that transmits light at least in the light entrance section (light entrance end) 40a and the light exit section (light exit end) 41a. Preferably, the light entrance section 40a and the light exit section 41a are transparent solids. Here, the term "transparent" refers to a property of having a light transmittance of approximately 80% or more. The storage section 43a is a solid formed of a material having water-stopping and moisture-permeable properties. The storage section 43a can be formed of a transparent resin material having properties such as thermoplasticity, thermosetting, and photopolymerization, and specifically, acrylic polymers, olefin polymers, vinyl polymers, cellulose polymers, amide polymers, fluorine polymers, urethane polymers, silicone polymers, and imide polymers can be used. Note that the portions of the storage section 43a other than the light entrance section 40a and the light exit section 41a do not necessarily need to be transparent, and materials different from the light entrance section 40a and the light exit section 41a can also be used. The container 43a may also be made of transparent glass, ceramic, or other inorganic material.

[0046] The storage section 43a may be a gel (agglomerate) that transmits light. Preferably, the storage section 43a is a transparent gel. Here, "transparent" refers to a property in which the light transmittance is approximately 80% or more. The storage section 43a is a gel (agglomerate) made of a material that is water-stopping and moisture-permeable. The storage section 43a is a gel (agglomerate) that can maintain its shape and can be arranged between the light source section 3 and the light irradiation section 5, and specifically, polyacrylic acid-based gel, silicone-based gel, cellulose-based gel, polyurethane-based gel, polyolefin-based gel, gelatin, etc. can be used.

[0047] The light absorbing medium 42a is a solid that transmits light. Preferably, the light absorbing medium 42a is a transparent solid. Here, the term "transparent" refers to a property of having a light transmittance of approximately 80% or more. The light absorbing medium 42a is a solid having a structure that allows moisture absorption and desorption, or a solid formed of a material having moisture absorption and desorption properties. The light absorbing medium 42a can be formed of a transparent resin material having properties such as thermoplasticity, thermosetting, and photopolymerization, and specifically, acrylic polymers, olefin polymers, vinyl polymers, cellulose polymers, amide polymers, fluorine polymers, urethane polymers, silicone polymers, and imide polymers can be adopted. The light absorbing medium 42a may be formed of inorganic materials such as transparent glass and ceramics.

[0048] The light absorbing medium 42a may be a gel (agglomerate) that transmits light. Preferably, the light absorbing medium 42a is a transparent gel. Here, "transparent" refers to a property in which the light transmittance is approximately 80% or more. The light absorbing medium 42a is a gel (agglomerate) made of a material having moisture absorbing and releasing properties, and specifically, polyacrylic acid gel, silicone gel, cellulose gel, polyurethane gel, polyolefin gel, gelatin, etc. can be used.

[0049] The light absorbing medium 42a may be an aerogel that transmits light. Preferably, the light absorbing medium 42a is a transparent aerogel. Here, "transparent" refers to a property of having a light transmittance of approximately 80% or more. The light absorbing medium 42a is a gel (agglomerate) made of a material that has moisture absorbing and releasing properties, and specifically, materials such as silica, alumina, chromium oxide, and tin oxide can be used.

[0050] The light absorbing medium 42a may be a liquid that transmits light. Preferably, the light absorbing medium 42a is a transparent liquid. Here, "transparent" refers to a property in which the light transmittance is approximately 80% or more. The light absorbing medium 42a is a liquid that has moisture absorbing and releasing properties, and specifically, water, oil, an organic solvent, etc. can be used.

[0051] The light absorbing medium 42a may be a gas that transmits light. Preferably, the light absorbing medium 42a is a transparent gas. Here, "transparent" refers to a property of having a light transmittance of approximately 80% or more. The light absorbing medium 42a may be a liquid having moisture absorbing and releasing properties, and specifically, may be air.

[0052] In the second embodiment, the light absorbing unit 4a is formed by filling the light absorbing medium 42a in the storage section 43a. The storage section 43a of the light absorbing unit 4a can be made of a material having a positive expansion coefficient with respect to the environmental temperature T at the location where the lighting device 1a is installed. By forming the storage section 43a using a material with such properties, the storage section 43a expands as a whole and its volume increases as the environmental temperature T increases. Therefore, the volume of the light absorbing medium 42a filled in the storage section 43a or the amount of moisture that can be absorbed by the light absorbing medium 42a increases. Conversely, the storage section 43a contracts as a whole and its volume decreases as the environmental temperature T decreases. Therefore, the volume of the light absorbing medium 42a filled in the storage section 43a or the amount of moisture that is the light absorbing medium 42 that can be absorbed by the light absorbing medium 42a decreases.

[0053] In a state where the environmental temperature T at the place where the lighting device 1a is installed is high (Th), the container 43a thermally expands and the volume of the light absorbing medium 42a that can be filled in the container 43a or the amount of moisture that can be absorbed by the light absorbing medium 42a (maximum capacity) increases. Therefore, the amount of components in the red to infrared wavelength band absorbed by the light absorbing medium 42a or moisture increases in the light Lp passing through the inside of the light absorbing unit 4a, and the difference between the original spectral distribution of the incident light L1 that enters the light absorbing unit 4a and the spectral distribution of the emitted light L2 that is emitted from the light absorbing unit 4a becomes large. In other words, the emitted light L2 with a bluish tone is emitted from the light absorbing unit 4a.

[0054] On the other hand, in a state where the environmental temperature T at the place where the lighting device 1a is installed is low (Tl), the storage section 43a thermally shrinks and the volume of the light absorbing medium 42a that can be filled in the storage section 43a or the amount of moisture that can be absorbed by the light absorbing medium 42a (maximum capacity) decreases. Therefore, the amount of components in the red to infrared wavelength band absorbed by the light absorbing medium 42a or moisture in the light Lp passing through the inside of the light absorbing section 4a decreases, and the difference between the original spectral distribution of the incident light L1 incident on the light absorbing section 4a and the spectral distribution of the emitted light L2 emitted from the light absorbing section 4a becomes small. In other words, the emitted light L2 emitted from the light absorbing section 4a does not have a bluish tone, or has a slightly bluish tone.

[0055] The light absorbing medium 42a may be a material whose light absorbing property or transmittance changes due to thermal response or phase change. In this case, it is expected that the rate of change of the spectral distribution corresponding to the temperature change in the place where the lighting device 1a is installed can be increased.

[0056] Embodiment 3 Fig. 8 is a diagram showing the configuration of the main parts of the illumination device 1b according to the third embodiment, and is a diagram showing a cross section including the optical axis of the light emitting element 30 and the thickness direction of the light irradiation unit 5. In Fig. 8, the same reference numerals are used for parts corresponding to those in Fig. 2(b), and duplicated explanations of the corresponding parts with the same reference numerals may be omitted. The illumination device 1b differs from the first embodiment in that it includes a light absorbing unit 4b.

[0057] The light absorbing portion 4b is formed by folding the sheet-like container 43b, so that the length dimension from the light entrance portion (light entrance end) 40b to the light exit portion (light exit end) 41b is increased. By forming the light absorbing portion 4b in this manner, the distance P of the light Lp passing through the inside of the light absorbing portion 4b from the light entrance portion 40b to the light exit portion 41b passing through the light absorbing medium 42b absorbed in the container 43b can be increased. In addition, at least the light entrance portion 40b and the light exit portion 41b of the container 43b have translucency, and the outer peripheral surface other than the light entrance portion 40b and the light exit portion 41b is subjected to total reflection treatment. Preferably, the light entrance portion 40b and the light exit portion 41b are transparent. Here, transparency refers to a property having a light transmittance of approximately 80% or more.

[0058] The incident light L1 incident on the light entrance portion 40b changes its spectral characteristics while being guided inside the light absorption portion 4b from the light entrance portion 40b toward the light exit portion (light exit end) 41b, and is then emitted from the light exit portion 4b.

[0059] Water molecules contained in the air are absorbed (adsorbed) as the light absorbing medium 42b in an amount corresponding to the relative humidity φ at the place where the lighting device 1b is installed in the storage section 43b. The moisture absorbed (adsorbed) in the storage section 43b acts as the light absorbing medium 42b for the light incident on the light absorbing section 4b. The light L1 emitted from the light source section 3 is incident on the light absorbing section 4b, and at least a part of the light Lp passing through the inside of the light absorbing section 4b passes through the moisture, which is the light absorbing medium 42b absorbed in the storage section 43b. At this time, the light Lp passing through the light absorbing medium 42b is affected by the light absorption characteristics of water, so that components in the wavelength band from red to infrared are absorbed relatively more. Therefore, the emitted light L2 that passes through the light absorbing medium 42b and is emitted from the light absorbing section 4 has a bluish tone than the light L1 emitted from the light source section 3. In this way, when the lighting device 1b is installed in a location where the relative humidity φ is such that water is absorbed in the accommodation section 43b as the light-absorbing medium 42b, the exiting light L2 has a spectral distribution different from the spectral distribution originally possessed by the incident light L1 emitted from the light source section 3 and incident on the light-absorbing section 4b from the light-receiving section 40b, and is emitted from the light-exiting section 41b.

[0060] The illumination device 1b is provided with the light-absorbing unit 4 having a long optical path length as described above, and therefore, even in a small space, it is possible to obtain a larger change in characteristics between the incident light L1 entering the light-absorbing unit 4b and the outgoing light L2 exiting from the light-absorbing unit 4b.

[0061] Although not shown in the figure, the light absorbing section 4b can be configured to have a longer optical path length even in a small space by strengthening the fibrous (fiber-like) storage section. Also, although not shown in the figure, the light absorbing section 4b can set various optical path lengths by adjusting the size, shape, and arrangement of the total reflection function of the storage section, and can adjust the length of the light absorbing medium b through which the light Lp guided from the light entrance section 40b to the light exit section 41b passes. Furthermore, although not shown in the figure, the light absorbing section 4b may be provided individually corresponding to each of the multiple light emitting elements 30. In this case, the individually provided light absorbing sections 4b may all have the same light absorption characteristics, or all or some of them may have different light absorption characteristics.

[0062] As described above, the lighting device 1b can adjust the length dimension from the light entrance section 40b to the light exit section 41b of the light absorption section 4b and can adjust the light absorption characteristics by the light absorption medium 42b, so that it is possible to obtain emitted light L2 or illumination light L5 with various characteristics. [Explanation of symbols]

[0063] 1, 1a, 1b lighting device, 2 housing (main body), 3 light source section, 4, 4a, 4b light absorption section, 5 light irradiation section (optical element), 9 mounting section, 30 light emitting element (LED), 31 substrate, 40, 40a, 40b light entrance section (light entrance end), 41, 41a, 41b light exit section (light exit end), 42, 42a, 42b light absorption medium, 43, 43a, 43b storage section, 50 incident section (incident end), 51 exit section (exit surface).

Claims

1. A light source unit; a light absorbing unit having water absorption or hygroscopicity, receiving light emitted from the light source unit, changing a spectral distribution by absorbing light of a specific wavelength band among the incident light, and emitting light with the changed spectral distribution; an optical element into which the light emitted from the light absorbing portion is incident and which emits illumination light toward an illumination space; The specific wavelength band changes depending on the amount of moisture absorbed by the light absorbing portion.

2. The light absorbing unit is 2. The lighting device according to claim 1, further comprising a housing portion for housing a light absorbing medium that changes the spectral distribution of incident light by absorbing light in the specific wavelength band.

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