Lighting device

Abstract

A lighting device (1) comprises a light guide plate (10) and a first light source (20) that emits light incident on the light guide plate (10). The light guide plate (10) includes a first end surface (11) on which light emitted from the first light source (20) is incident, a first main surface (13) through which light incident on the light guide plate (10) is emitted outside of the light guide plate (10), and a second main surface (14), being the reverse surface from the first main surface (13). The second main surface (14) includes a first inclined surface (14a) that reflects the light incident on the light guide plate (10) from the first end surface (11). The first inclined surface (14a) is inclined so as to approach the first main surface (13) the farther away the first inclined surface (14a) is from the first end surface (11).

Description

lighting equipment

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

[0002] An edge-lit lighting device is known as a lighting device using a light guide plate. The edge-lit lighting device includes a planar light guide plate having opposing first and second main surfaces, and a light source disposed opposite the end surface of the light guide plate. In this lighting device, light from the light source incident on the end surface of the light guide plate is guided through the light guide plate while repeatedly undergoing total reflection at the first and second main surfaces of the light guide plate, and is emitted to the outside of the light guide plate from the first or second main surface, which serves as the light exit surface.

[0003] Japanese Patent Application Laid-Open No. 2023-120567

[0004] In conventional lighting devices using a light guide plate, both the first and second main surfaces of the light guide plate are flat. Therefore, some of the light incident on the light guide plate travels straight from one end surface to the other end surface of the light guide plate without being able to exit from the light exit surface (e.g., the first main surface) of the light guide plate. Therefore, conventional lighting devices using a light guide plate have poor light utilization efficiency. In particular, when light is incident on one end surface of the light guide plate, if the distance between the one end surface and the other end surface of the light guide plate becomes short, the proportion of light that travels straight from one end surface to the other end surface of the light guide plate increases.

[0005] In addition, there is a demand for an illumination device that can control the light distribution of illumination light. In this case, if a control circuit for controlling the light distribution of illumination light is built into an illumination device using a light guide plate, the thickness of the illumination device increases, hindering the thinning of the illumination device.

[0006] The present invention has been made to solve such problems, and aims to provide an illumination device that uses a light guide plate, which can improve the light utilization efficiency and can prevent the device from being hindered in terms of thinness even when a circuit module such as a control circuit is built in.

[0007] In order to achieve the above object, one aspect of the lighting device according to the present invention includes a light guide plate and a first light source that emits light to be incident on the light guide plate, wherein the light guide plate has a first end surface into which the light emitted from the first light source is incident, a first main surface through which the light that has entered the light guide plate is emitted to an exterior of the light guide plate, and a second main surface facing away from the first main surface, wherein the second main surface has a first inclined surface that reflects the light that has entered the light guide plate from the first end surface, and the first inclined surface is inclined so as to approach the first main surface with increasing distance from the first end surface.

[0008] According to the present invention, in a lighting device using a light guide plate, it is possible to improve the light utilization efficiency and prevent the device from being hindered in terms of thinning even if a circuit module such as a control circuit is built in.

[0009] FIG. 1 is a cross-sectional view of an illumination device according to an embodiment. FIG. 2 is a plan view of a light guide plate, a first light source, and a second light source in the illumination device according to the embodiment. FIG. 3 is an enlarged perspective view of the light guide plate in the illumination device according to the embodiment. FIG. 4A is a diagram showing the optical function of the illumination device and the light distribution of the illumination light when only the first light source is made to emit light. FIG. 4B is a diagram showing the optical function of the illumination device and the light distribution of the illumination light when only the second light source is made to emit light. FIG. 4C is a diagram showing the optical function of the illumination device and the light distribution of the illumination light when both the first light source and the second light source are made to emit light. FIG. 5 is a diagram showing a state when the light distribution of the illumination light of the illumination device according to the embodiment is controlled. FIG. 6 is a cross-sectional view of an illumination device according to a first modification. FIG. 7 is a cross-sectional view of an illumination device according to a second modification. FIG. 8 is a cross-sectional view of an illumination device according to a third modification.

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that each of the embodiments described below represents a specific example of the present invention. Therefore, the numerical values, shapes, materials, components, arrangement positions and connection forms of the components, etc. shown in the following embodiments are merely examples and are not intended to limit the present invention. Therefore, among the components in the following embodiments, components that are not described in the independent claims that represent the highest concept of the present invention will be described as optional components.

[0011] Each figure is a schematic diagram and is not necessarily an exact illustration. Therefore, the scales and the like do not necessarily match in each figure. In each figure, substantially the same configurations are assigned the same reference numerals, and redundant explanations are omitted or simplified. In each figure, the X-axis, Y-axis, and Z-axis represent the three axes of a three-dimensional Cartesian coordinate system. In this embodiment, the Z-axis direction is the vertical direction, and the direction perpendicular to the Z-axis (the direction parallel to the XY plane) is the horizontal direction. The X-axis and Y-axis are orthogonal to each other and are both orthogonal to the Z-axis.

[0012] Furthermore, in this specification, the terms "up" and "down" do not refer to the up direction (vertically upward) and down direction (vertically downward) in absolute spatial recognition, but are used as terms defined by a relative positional relationship.

[0013] (Embodiment) First, the configuration of an illumination device 1 according to an embodiment will be described with reference to Fig. 1, Fig. 2, and Fig. 3. Fig. 1 is a cross-sectional view of the illumination device 1 according to the embodiment. Fig. 2 is a plan view of a light guide plate 10, a first light source 20, and a second light source 30 in the illumination device 1 according to the embodiment. Fig. 3 is an enlarged perspective view showing a portion of the light guide plate 10 used in the illumination device 1 according to the embodiment.

[0014] The lighting device 1 emits illumination light toward a predetermined illumination surface. As shown in Figures 1 and 2, the lighting device 1 includes a light guide plate 10, a first light source 20, a second light source 30, a circuit module 40, and a housing 50. The lighting device 1 in this embodiment is an edge-light type lighting device in which the first light source 20 and the second light source 30 are arranged opposite end surfaces of the light guide plate 10.

[0015] The light guide plate 10 is an optical member that has the function of guiding light. The light guide plate 10 is a light guide member that is generally flat. The thickness of the light guide plate 10 (thickness at the edge) is, for example, 2 mm to 20 mm. In this embodiment, the thickness of the light guide plate 10 is 3.5 mm, but is not limited to this.

[0016] 2, the light guide plate 10 has a rectangular shape in plan view. In this embodiment, the longitudinal direction of the light guide plate 10 is the Y-axis direction, and the lateral direction of the light guide plate 10 is the X-axis direction. As an example, the length of the light guide plate 10 in the longitudinal direction (vertical length) is 100 mm to 10,000 mm, and the length of the light guide plate 10 in the lateral direction (horizontal length: width) is 5 mm to 100 mm. The aspect ratio (vertical length / lateral length) of the rectangular light guide plate 10 is 4 to 20. In this embodiment, the length of the light guide plate 10 in the longitudinal direction is 250 mm, the length of the light guide plate 10 in the lateral direction is 25 mm, and the aspect ratio is 10.

[0017] The light guide plate 10 is a light-transmitting member that is translucent at least in the visible light region. The transmittance of the light guide plate 10 is preferably high, and is preferably at least 50% or more. Specifically, the light guide plate 10 is preferably transparent to visible light. A transparent light guide plate 10 has a transmittance high enough to allow the viewer to see through it. In this case, the transmittance of the transparent light guide plate 10 to visible light is 70% or more, preferably 80% or more, and more preferably 90% or more. The light guide plate 10 may be translucent not only in the visible light region but also in the near-infrared region. In other words, the light guide plate 10 may be translucent in both the visible light region and the near-infrared region.

[0018] The light guide plate 10 is made of a light-transmitting material. The light guide plate 10 is made of, for example, a transparent resin material or a transparent glass material. Examples of the transparent resin material that can be used include polycarbonate resin, silicone resin, and acrylic resin. When the lighting device 1 is used in a moving object such as an aircraft, the light guide plate 10 is preferably made of a flame-retardant resin material. Therefore, in this case, the light guide plate 10 preferably uses polycarbonate resin or silicone resin as the flame-retardant resin material. In this embodiment, a transparent acrylic substrate is used as the light guide plate 10.

[0019] The light guide plate 10 has a first end face 11 and a second end face 12. Each of the first end face 11 and the second end face 12 is one of a plurality of side faces of the light guide plate 10. In the present embodiment, the light guide plate 10 is a rectangular flat plate, and therefore each of the first end face 11 and the second end face 12 is one of four side faces of the rectangular flat plate, and has an elongated rectangular shape.

[0020] The second end face 12 is a face facing away from the first end face 11. In this embodiment, the first end face 11 and the second end face 12 face away from each other in the X-axis direction, which is the short-side direction of the light guide plate 10. In other words, the first end face 11 and the second end face 12 face each other in the X-axis direction.

[0021] Therefore, the direction from the first end face 11 to the second end face 12 is the short-side direction of the light guide plate 10. The first end face 11 and the second end face 12 extend in the Y-axis direction, which is the longitudinal direction of the light guide plate 10. The first end face 11 and the second end face 12 are each flat and substantially parallel to each other. Note that the first end face 11 and the second end face 12 are not limited to being flat and may be curved surfaces that are concavely or convexly curved.

[0022] The first end surface 11 and the second end surface 12 are incident surfaces (light-entering surfaces) through which light enters the light guide plate 10 from the outside of the light guide plate 10 .

[0023] Specifically, the first end surface 11 is a first light incident surface onto which light emitted from the first light source 20 is incident. The first end surface 11 faces the first light source 20. In other words, the first end surface 11 is a surface on the first light source 20 side.

[0024] The second end surface 12 is a second light incident surface onto which light emitted from the second light source 30 is incident. The second end surface 12 faces the second light source 30. In other words, the second end surface 12 is a surface on the second light source 30 side.

[0025] Furthermore, the light guide plate 10 has a first major surface 13 and a second major surface 14. The second major surface 14 is a surface facing away from the first major surface 13. The first major surface 13 and the second major surface 14 face each other in the Z-axis direction, which is the thickness direction of the light guide plate 10. In the present embodiment, the light guide plate 10 is a rectangular flat plate, and therefore the shape of each of the first major surface 13 and the second major surface 14 in a plan view is rectangular.

[0026] The first main surface 13 is a light exit surface (light exit surface) through which light incident on the light guide plate 10 is emitted to the outside of the light guide plate 10. In other words, the first main surface 13 is a light extraction surface for extracting light guided within the light guide plate 10 to the outside. In this embodiment, the first main surface 13 is a flat surface. Specifically, the first main surface 13 is a flat surface on which no uneven structure such as a prism is formed.

[0027] A diffusion film 60 is provided on the first main surface 13. In this embodiment, the diffusion film 60 is disposed in contact with the first main surface 13 so as to cover the entire surface of the first main surface 13.

[0028] The diffusion film 60 is an optical member that is translucent and light-diffusing. The diffusion film 60 is formed from a translucent resin material, such as polycarbonate resin, silicone resin, or acrylic resin. As an example, the diffusion film 60 is a milky white sheet-like diffusion plate in which a light-diffusing material (light-scattering material) is dispersed in a translucent resin material. The diffusion film 60 may have a total light transmittance of 50% to 95%. In this embodiment, the diffusion film 60 used has a haze value of 30% and a total light transmittance of 90%.

[0029] In this way, by providing the diffusion film 60 on the first main surface 13, the light emitted from the first main surface 13 of the light guide plate 10 is diffused (scattered) by the diffusion film 60, passes through the diffusion film 60, and then exits from the diffusion film 60. In this case, since the diffusion film 60 forms the outer surface of the lighting device 1, the outer surface of the diffusion film 60 serves as a light-emitting surface that diffuses the light from the light guide plate 10 and emits light in a pseudo-light-emitting manner.

[0030] The second main surface 14 is a light control surface that controls the light guided within the light guide plate 10. In this embodiment, the second main surface 14 has a function of reflecting the light guided within the light guide plate 10.

[0031] Specifically, as shown in FIG. 1 , the second major surface 14 has a first inclined surface 14a that reflects light that is incident from the first end surface 11 and guided through the light guide plate 10. Specifically, the first inclined surface 14a reflects light from the first light source 20 that is incident from the first end surface 11. The first inclined surface 14a is inclined so as to approach the first major surface 13 with increasing distance from the first end surface 11. The inclination angle of the first inclined surface 14a varies depending on the thinnest portion 15, but is, for example, 2° to 20°. In this embodiment, the inclination angle of the first inclined surface 14a is 5°. As shown in FIG. 2 , the first inclined surface 14a extends over the entire longitudinal direction of the light guide plate 10.

[0032] The first inclined surface 14 a may also reflect light that is incident from the second end surface 12 and guided through the light guide plate 10. In other words, the first inclined surface 14 a may also reflect light from the second light source 30 that is incident from the second end surface 12.

[0033] As shown in FIG. 1 , a reflective member 70 is provided on the first inclined surface 14 a. The reflective member 70 is a light-reflective member that diffusely reflects (scatters) incident light. The reflective member 70 may be a film-like light-reflective film, a sheet-like light-reflective sheet, or a film-like light-reflective film, but is not limited to such thin members. In addition, in this embodiment, the reflective member 70 is provided on the entire surface of the first inclined surface 14 a, but this is not limiting. In other words, the reflective member 70 may be provided on only a portion of the first inclined surface 14 a. For example, the reflective member 70 may be provided on half of the area of ​​the first inclined surface 14 a.

[0034] The reflective member 70 is made of, for example, a resin material or a metal material. Specifically, the reflective member 70 may be a white resin sheet or film made of a resin material such as PBT (polybutylene terephthalate), or a metal film made of a metal material such as aluminum or silver.

[0035] In this way, by providing the reflecting member 70 on the first inclined surface 14 a, the light that reaches the first inclined surface 14 a can be diffused and reflected by the reflecting member 70. The light reflected by the first inclined surface 14 a travels toward the first main surface 13 and is emitted from the first main surface 13 to the outside of the light guide plate 10.

[0036] The second major surface 14 also has a second inclined surface 14b that reflects light that is incident from the second end surface 12 and guided through the light guide plate 10. The second inclined surface 14b is inclined so as to approach the first major surface 13 with increasing distance from the second end surface 12. The inclination angle of the second inclined surface 14b varies depending on the thinnest portion 15, but is, for example, 2° to 20°. In this embodiment, the inclination angle of the second inclined surface 14b is 5°. In other words, the inclination angle of the first inclined surface 14a and the inclination angle of the second inclined surface 14b are the same. As shown in FIG. 2 , the second inclined surface 14b extends over the entire longitudinal direction of the light guide plate 10, similar to the first inclined surface 14a.

[0037] The second inclined surface 14b may also reflect light that is incident from the first end surface 11 and guided through the light guide plate 10. In other words, the second inclined surface 14b may also reflect light from the first light source 20 that is incident from the first end surface 11.

[0038] In this embodiment, the second inclined surface 14b is not provided with a reflective film, and is an exposed surface exposed to the air layer. Therefore, light that reaches the second inclined surface 14b is reflected by total reflection at the second inclined surface 14b, which is the interface between the light guide plate 10 and the air layer. The light reflected at the second inclined surface 14b travels toward the first main surface 13 and is emitted from the first main surface 13 to the outside of the light guide plate 10.

[0039] The first inclined surface 14a and the second inclined surface 14b are connected on the second main surface 14. Therefore, the first inclined surface 14a and the second inclined surface 14b have a V-shaped cross section. In other words, the light guide plate 10 has a shape in which a part of the second main surface 14 is recessed in a V-shape. Specifically, a shallow groove with a V-shaped cross section is formed on the second main surface 14 of the light guide plate 10.

[0040] The connection between the first inclined surface 14a and the second inclined surface 14b is the thinnest portion 15 of the light guide plate 10. The thinnest portion 15 is the portion of the light guide plate 10 where the thickness is the smallest. In this embodiment, the inclination angle of the first inclined surface 14a and the inclination angle of the second inclined surface 14b are the same, and the thinnest portion 15 is located at the midpoint between the first end surface 11 and the second end surface 12. Note that when the thickness of the light guide plate 10 (thickness of the end portion) where the first inclined surface 14a and the second inclined surface 14b are not formed is 2 mm to 20 mm as described above, the thickness of the thinnest portion 15 is, for example, 1 mm to 15 mm. In this embodiment, the thickness of the light guide plate 10 is 3.5 mm, and the thickness of the thinnest portion 15 is 1.5 mm.

[0041] The first light source 20 and the second light source 30 are light-emitting devices that emit light to be incident on the light guide plate 10. In the present embodiment, each of the first light source 20 and the second light source 30 is an LED module including a light-emitting diode (LED). The first light source 20 and the second light source 30 emit, for example, white light.

[0042] The first light source 20 has a first substrate 21 and a first light-emitting element 22 arranged on the first substrate 21. The first substrate 21 is a mounting substrate for mounting the first light-emitting element 22. One or more first light-emitting elements 22 are mounted on the first substrate 21. In this embodiment, a plurality of first light-emitting elements 22 are mounted on the first substrate 21.

[0043] The second light source 30 has a second substrate 31 and a second light-emitting element 32 arranged on the second substrate 31. The second substrate 31 is a mounting substrate for mounting the second light-emitting element 32. One or more second light-emitting elements 32 are mounted on the second substrate 31. In this embodiment, a plurality of second light-emitting elements 32 are mounted on the second substrate 31.

[0044] Each of the first substrate 21 and the second substrate 31 is an elongated substrate, such as a wiring substrate on which metal wiring is formed in a predetermined pattern. The base substrate of the first substrate 21 and the second substrate 31 may be, for example, a resin substrate, a ceramic substrate, or a metal substrate coated with an insulating film.

[0045] Each of the first light-emitting element 22 and the second light-emitting element 32 is an LED light source configured with an LED. Specifically, each of the first light-emitting element 22 and the second light-emitting element 32 is a white LED light source that emits white light. Each of the first light-emitting element 22 and the second light-emitting element 32 is, for example, an individually packaged surface-mounted (SMD: Surface Mount Device) type LED element. Therefore, each of the first light source 20 and the second light source 30 is an SMD type LED module. In this case, each of the first light-emitting element 22 and the second light-emitting element 32 includes a white resin or ceramic container (package) having a recess, one or more LED chips primarily mounted on the bottom of the recess, and a sealing member filled in the recess of the container and sealing the LED chips. The sealing member is made of a translucent resin material such as silicone resin. A phosphor-containing resin containing a wavelength conversion material such as a phosphor can be used as the sealing member.

[0046] The LED chip is an example of a semiconductor light-emitting element that emits light using a predetermined DC power, and is a bare chip that emits monochromatic visible light. The LED chip is, for example, a blue LED chip that emits blue light when powered. In this case, in order to obtain white light, the sealing member contains a yellow phosphor such as YAG (yttrium aluminum garnet) that fluoresces using the blue light from the blue LED chip as excitation light.

[0047] Each of the first light-emitting element 22 and the second light-emitting element 32 configured in this manner is a white LED element composed of a blue LED chip and a yellow phosphor. In this case, the yellow phosphor absorbs a portion of the blue light emitted by the blue LED chip, becomes excited, and emits yellow light. This yellow light mixes with the blue light not absorbed by the yellow phosphor to produce white light. Note that the sealing member is not limited to only the yellow phosphor, and may also contain a red phosphor and a green phosphor.

[0048] In the first light source 20, the plurality of first light-emitting elements 22 are arranged in a line along the longitudinal direction of the first substrate 21. Therefore, the first light source 20 is a line light source that emits line-shaped light. In this embodiment, 40 first light-emitting elements 22 connected in series are arranged in a row at equal intervals.

[0049] Similarly, in the second light source 30, the plurality of second light-emitting elements 32 are arranged in a line along the longitudinal direction of the second substrate 31. Therefore, the second light source 30 is also a line light source that emits line-shaped light. In this embodiment, 40 second light-emitting elements 32 connected in series are arranged in a row at equal intervals.

[0050] The first light source 20 and the second light source 30 have the same configuration. Specifically, the first substrate 21 and the second substrate 31 are mounting substrates of the same shape, and the first light-emitting elements 22 and the second light-emitting elements 32 are the same product. In addition, the number of first light-emitting elements 22 (mounted number) and the number of second light-emitting elements 32 (mounted number) are also the same.

[0051] The first light source 20 emits light to be incident on the first end surface 11 (first light incident surface) of the light guide plate 10. The first light source 20 is arranged to the side of the first end surface 11 of the light guide plate 10. In the present embodiment, the first light source 20 is arranged opposite the first end surface 11, and the light exit surface of the first light source 20 faces the first end surface 11. Specifically, the first light source 20 is arranged such that the light emitting surface of the first light emitting element 22 faces the first end surface 11. The light emitted from the first light source 20 enters the light guide plate 10 from the first end surface 11 of the light guide plate 10. The optical axis of the first light source 20 is oriented from the first end surface 11 toward the second end surface 12.

[0052] On the other hand, the second light source 30 emits light to be incident on the second end surface 12 (second light incident surface) of the light guide plate 10. The second light source 30 is arranged to the side of the second end surface 12 of the light guide plate 10. In the present embodiment, the second light source 30 is arranged opposite the second end surface 12, and the light exit surface of the second light source 30 faces the second end surface 12. Specifically, the second light source 30 is arranged such that the light emitting surface of the second light emitting element 32 faces the second end surface 12 of the light guide plate 10. The light emitted from the second light source 30 enters the light guide plate 10 from the second end surface 12 of the light guide plate 10. The optical axis of the second light source 30 is oriented from the second end surface 12 toward the first end surface 11.

[0053] The first light source 20 and the second light source 30 emit light using power supplied from the circuit module 40. Specifically, DC power is supplied from the circuit module 40 to the multiple first light-emitting elements 22 of the first light source 20, causing the multiple first light-emitting elements 22 to emit light. The light emitted from the first light-emitting elements 22 becomes the emitted light of the first light source 20. Similarly, DC power is supplied from the circuit module 40 to the multiple second light-emitting elements 32 of the second light source 30, causing the multiple second light-emitting elements 32 to emit light. The light emitted from the second light-emitting elements 32 becomes the emitted light of the second light source 30.

[0054] In addition, separately from the first light source 20 and the second light source 30 or as part of the first light source 20 and the second light source 30, if necessary, optical components such as a light distribution variable component such as a lens that changes the light distribution of the light emitted from the first light source 20 and the second light source 30, a filter that controls the wavelength of the light emitted from the first light source 20 and the second light source 30, or a diffuser plate that scatters and transmits the light emitted from the first light source 20 and the second light source 30 may be provided.

[0055] The circuit module 40 has a drive circuit that controls the light emission states of the first light source 20 and the second light source 30. For example, the circuit module 40 has, as the drive circuit, a power supply circuit (lighting circuit) that supplies power to the first light source 20 and the second light source 30, and a control circuit that controls the light emission states of the first light source 20 and the second light source 30 by controlling the power supply circuit.

[0056] As shown in FIG. 1 , the circuit module 40 includes a circuit board 41 and a plurality of circuit elements 42 mounted on the circuit board 41. The circuit board 41 is a printed circuit board (PCB) on which metal wiring such as copper foil is formed in a predetermined pattern. The plurality of circuit elements 42 constitute a drive circuit (power supply circuit, control circuit). The plurality of circuit elements 42 may be, for example, capacitance elements such as electrolytic capacitors and ceramic capacitors, coil elements (inductors) such as choke coils and choke transformers, transistor elements such as FETs, resistance elements such as resistors, or diodes. Note that the circuit module 40 may also include other control circuits, such as a wireless communication circuit.

[0057] The power supply circuit in the circuit module 40 generates power for making the first light source 20 and the second light source 30 emit light, and supplies the power to the first light source 20 and the second light source 30. For example, the power supply circuit converts AC power from an external power source such as a commercial power source into DC power of a predetermined level by rectifying, smoothing, stepping down, etc., and supplies the DC power to the first light source 20 and the second light source 30. The power supply circuit may include a constant current circuit.

[0058] The control circuit in the circuit module 40 controls the power supply circuit in accordance with an external lighting control signal input to the lighting device 1. Specifically, upon receiving the lighting control signal, the control circuit controls the power supply circuit in accordance with the lighting control signal so that the power supply circuit supplies a predetermined current value to each of the first light source 20 and the second light source 30.

[0059] In this case, because the first light source 20 and the second light source 30 are connected in parallel, the power supply circuit having a constant current circuit is controlled by the control circuit to supply current to each of the first light source 20 and the second light source 30 at a current ratio according to the illumination control signal. In other words, the control circuit controls the power supply circuit so that current is diverted to the first light source 20 and the second light source 30 at a current ratio according to the illumination control signal, while keeping the total current (total current) of the current supplied to the first light source 20 and the current supplied to the second light source 30 constant. This changes the current ratio of the currents flowing through the first light source 20 and the second light source 30, and therefore changes the ratio (light intensity ratio) of the amount of light emitted from the first light source 20 to the amount of light emitted from the second light source 30. In other words, the optical output ratio of the light emitted by the first light source 20 to the light emitted by the second light source 30 changes. In this way, the control circuit of the circuit module 40 controls the ratio between the amount of light emitted from the first light source 20 and the amount of light emitted from the second light source 30 .

[0060] The housing 50 houses the light guide plate 10, the first light source 20, the second light source 30, and the circuit module 40. The housing 50 is, for example, a cylindrical box-shaped housing member with a bottom and an opening. The housing 50 is made of, for example, a metal material or a resin material. The surface of the housing 50 is preferably black. This allows the housing 50 to absorb stray light leaking from the light guide plate 10. A transparent panel may be provided to cover the opening of the housing 50.

[0061] The circuit module 40 is disposed between the second main surface 14 of the light guide plate 10 and the bottom surface of the housing 50. Specifically, the circuit module 40 is located between the first inclined surface 14a of the light guide plate 10 and the housing 50, and also between the second inclined surface 14b of the light guide plate 10 and the housing 50. In other words, the circuit module 40 is housed in a groove having a V-shaped cross section formed in the light guide plate 10 by the first inclined surface 14a and the second inclined surface 14b. Therefore, the circuit module 40 is preferably disposed between the thinnest part 15 of the light guide plate 10 and the bottom surface of the housing 50.

[0062] Next, the illumination light emitted by the illumination device 1 will be described with reference to Figures 4A, 4B, and 4C. Figure 4A is a diagram showing the optical action of the illumination device 1 and the light distribution of the illumination light when only the first light source 20 is made to emit light. Figure 4B is a diagram showing the optical action of the illumination device 1 and the light distribution of the illumination light when only the second light source 30 is made to emit light. Figure 4C is a diagram showing the optical action of the illumination device 1 and the light distribution of the illumination light when both the first light source 20 and the second light source 30 are made to emit light.

[0063] 4A , when only the first light source 20 of the first light source 20 and the second light source 30 is activated, only the light emitted from the first light source 20 (first light-emitting element 22) enters the light guide plate 10. Specifically, the light emitted from the first light source 20 enters the light guide plate 10 from the first end surface 11 of the light guide plate 10 and is guided within the light guide plate 10. In this case, since the reflecting member 70 is provided on the first inclined surface 14 a formed on the first end surface 11 side of the light guide plate 10, the light guided within the light guide plate 10 that reaches the first inclined surface 14 a is diffusely reflected (scattered reflected) by the reflecting member 70. The light reflected by the reflecting member 70 travels toward the first main surface 13 and is emitted from the first main surface 13 to the outside of the light guide plate 10. Note that some of the light emitted from the first light source 20 is not reflected by the first inclined surface 14a (reflecting member 70), but is guided within the light guide plate 10 while undergoing total reflection, and is then emitted to the outside of the light guide plate 10 from the first main surface 13. As a result, light is emitted from the entire surface of the first main surface 13 of the light guide plate 10. The light emitted from the entire surface of the first main surface 13 is diffused by the diffusion film 60, and is irradiated as illumination light of the lighting device 1 toward the floor surface 100, which is the illumination surface.

[0064] In this case, the light distribution of the illumination light emitted by the illumination device 1 becomes asymmetric in the direction from the first end face 11 to the second end face 12 (X-axis direction) about the center line L passing through the center of the light guide plate 10. Furthermore, in this case, the illuminance distribution of the illumination device 1 when the illumination light from the illumination device 1 is irradiated onto the floor surface 100 has only one peak.

[0065] 4B , when only the second light source 30 of the first light source 20 and the second light source 30 is caused to emit light, only the light emitted from the second light source 30 (second light-emitting element 32) enters the light guide plate 10. Specifically, the light emitted from the second light source 30 enters the light guide plate 10 from the second end surface 12 of the light guide plate 10 and is guided within the light guide plate 10. In this case, of the light guided within the light guide plate 10, the light that reaches the second inclined surface 14b is reflected by total reflection at the second inclined surface 14b, which is the interface between the light guide plate 10 and the air layer. The light reflected at the second inclined surface 14b travels toward the first major surface 13 and is emitted from the first major surface 13 to the outside of the light guide plate 10. Note that some of the light emitted from the second light source 30 is not reflected by the second inclined surface 14b, but is guided within the light guide plate 10 while undergoing total internal reflection, and is then emitted to the outside of the light guide plate 10 from the first main surface 13. As a result, light is emitted from the entire surface of the first main surface 13 of the light guide plate 10. The light emitted from the entire surface of the first main surface 13 is diffused by the diffusion film 60, and is irradiated as illumination light of the lighting device 1 toward the floor surface 100, which is the illumination surface.

[0066] In this case as well, the light distribution of the illumination light emitted by the illumination device 1 is asymmetric in the direction from the first end face 11 to the second end face 12 (X-axis direction) about the center line L passing through the center of the light guide plate 10. Also in this case as well, the illuminance distribution of the illumination device 1 when the illumination light from the illumination device 1 is irradiated onto the floor surface 100 has only one peak.

[0067] In this way, the light distribution of the illumination light from the lighting device 1 is asymmetrical about the center line L whether only the first light source 20 is made to emit light or only the second light source 30 is made to emit light, but when only the first light source 20 is made to emit light, the light from the first light source 20 is diffusely reflected by the reflecting member 70. For this reason, the illumination light from the lighting device 1 when only the first light source 20 is made to emit light has a light distribution with a larger luminous distribution angle than the illumination light from the lighting device 1 when only the second light source 30 is made to emit light, and therefore the illumination area of ​​the illumination light irradiated onto the floor surface 100 is wider.

[0068] 4C , when both the first light source 20 and the second light source 30 are activated, the light distribution of the lighting device 1 is a combination of the light distribution shown in FIG. 4A and the light distribution shown in FIG. 4B . In this case, the light distribution of the lighting device 1 is asymmetric about the center line L passing through the center of the light guide plate 10 in the direction from the first end surface 11 to the second end surface 12 (the X-axis direction). In this case, the illuminance distribution of the lighting device 1 when the illumination light from the lighting device 1 is irradiated onto the floor surface 100 has only one peak. This is because there is a large overlap between the illuminance distribution of the lighting device 1 when only the first light source 20 is activated and the illuminance distribution of the lighting device 1 when only the second light source 30 is activated. Specifically, when compared with the central illuminance (peak of illuminance distribution) on the illuminated surface due to the light distribution of the first light source 20 and the central illuminance (peak of illuminance distribution) on the illuminated surface due to the light distribution of the second light source 30, the illuminance distribution obtained by superimposing the light distribution of the first light source 20 and the light distribution of the second light source 30 exceeds the central illuminance of both the first light source 20 and the second light source 30. As a result, in the illuminance distribution of the lighting device 1 when both the first light source 20 and the second light source 30 are made to emit light, the overlapping portion of the illuminance distribution appears as a peak, and the peak of the illuminance distribution of the lighting device 1 when only the first light source 20 is made to emit light and the peak of the illuminance distribution of the lighting device 1 when only the second light source 30 is made to emit light disappear.

[0069] 4A to 4C are for the case where the lighting device 1 is disposed substantially parallel to the floor surface 100 and the distance from the lighting device 1 to the floor surface 100 is 160 mm or more (for example, 640 mm). In other words, in this case, even if both the first light source 20 and the second light source 30 are turned on, the illuminance distribution of the lighting device 1 when the illumination light from the lighting device 1 is irradiated onto the floor surface 100 will have only one peak. In order to obtain the light distribution and illuminance distribution shown in FIGS. 4A to 4C, the upper limit of the distance from the lighting device 1 to the floor surface 100 is not particularly limited, but is, for example, 2500 mm or less, preferably 1120 mm or less.

[0070] Next, the light distribution control of the illumination light emitted by the lighting device 1 will be described. In the lighting device 1, the light intensity ratio (light output ratio) of the first light source 20 and the second light source 30 can be changed by controlling the ratio of the currents supplied to the first light source 20 and the second light source 30 using the circuit module 40. This allows the light distribution of the illumination light from the lighting device 1 to be changed. As a result, the illuminance distribution of the illumination light from the lighting device 1 can also be changed. For example, as shown in FIG. 5 , by changing the light intensity ratio of the first light source 20 and the second light source 30 in five steps, the light distribution and illuminance distribution of the illumination light from the lighting device 1 can be switched between five steps. FIG. 5 is a diagram illustrating the state when the light distribution of the illumination light from the lighting device 1 according to the embodiment is controlled.

[0071] As shown in FIG. 5 , when the light intensity of the first light source 20 is “A” and the light intensity of the second light source 30 is “B,” (a) shows the light distribution and illuminance distribution when A:B=0%:100% (first mode), (b) shows the light distribution and illuminance distribution when A:B=25%:75% (second mode), (c) shows the light distribution and illuminance distribution when A:B=50%:50% (third mode), (d) shows the light distribution and illuminance distribution when A:B=75%:25% (fourth mode), and (e) shows the light distribution and illuminance distribution when A:B=100%:0% (fifth mode).

[0072] In (a) to (e) of FIG. 5, the left diagram is an image of the light distribution, and the right diagram shows the illuminance distribution on the floor surface 100. In the left diagram of FIG. 5, "A" written next to the lighting device 1 indicates the first light source 20 side, and "B" indicates the second light source 30 side. The arrows of each light distribution in the left diagram of FIG. 5 indicate the light distribution center (maximum light intensity), i.e., the position of maximum illuminance on the floor surface 100 (illumination surface). The illuminance distributions in the right diagram of FIG. 5 are obtained when the lighting device 1 shown in (a) of FIG. 5 is installed at d1 = 190 mm and d2 = 1400 mm. The isoilluminance lines in each illuminance distribution indicate that the illuminance increases toward the center. The numerical values ​​of each illuminance distribution in the right diagram of FIG. 5 are expressed in millimeters.

[0073] 5(a) to 5(e), the light distribution and illuminance distribution of the illumination light of the lighting device 1 can be changed by changing the ratio (light amount ratio) between the amount of light emitted from the first light source 20 and the amount of light emitted from the second light source 30. Specifically, by increasing the ratio of the amount of light of the second light source 30 to the amount of light of the first light source 20, the center of the light distribution and the center of the illuminance distribution of the illumination light of the lighting device 1 can be shifted from the right region of the lighting device 1 to the left region (wall side region) of the lighting device 1.

[0074] 5, the light distribution and illuminance distribution of the illumination light from the lighting device 1 are changed in a stepwise (digital) manner, but the present invention is not limited to this. For example, the light distribution and illuminance distribution of the illumination light from the lighting device 1 may be changed gradually in an analog manner.

[0075] As described above, the lighting device 1 according to the present embodiment includes a light guide plate 10 and a first light source 20 that emits light to be incident on the light guide plate 10. The light guide plate 10 has a first end surface 11 onto which the light emitted from the first light source 20 is incident, a first main surface 13 from which the light that has entered the light guide plate 10 is emitted to the outside of the light guide plate 10, and a second main surface 14 facing away from the first main surface 13. The second main surface 14 of the light guide plate 10 has a first inclined surface 14a that reflects the light that has entered the light guide plate 10 from the first end surface 11, and the first inclined surface 14a is inclined so as to approach the first main surface 13 with increasing distance from the first end surface 11.

[0076] As described above, in the lighting device 1 according to the present embodiment, the first inclined surface 14a that reflects light incident from the first end surface 11 of the light guide plate 10 is formed on the second main surface 14 of the light guide plate 10, so that the light that enters the light guide plate 10 from the first end surface 11 can be reflected by the first inclined surface 14a. This makes it possible to reduce the amount of light that enters from the first end surface 11 and travels straight from the first end surface 11 to the second end surface 12 of the light guide plate 10 without being able to exit from the first main surface 13, which is the light exit surface. As a result, it is possible to increase the amount of light that exits to the outside from the first main surface 13, which is the light exit surface, and therefore improve the light utilization efficiency.

[0077] Furthermore, by forming the first inclined surface 14a on the light guide plate 10, a recessed groove can be formed on the second main surface 14 of the light guide plate 10. This allows the circuit module 40 to be housed in this groove. As a result, even if the circuit module 40 is built into the lighting device 1, the thickness of the lighting device 1 can be prevented from increasing. In other words, it is possible to prevent the lighting device 1 from being hindered from being made thinner.

[0078] As described above, according to the lighting device 1 of this embodiment, even though it is a lighting device 1 that uses a light guide plate 10, it is possible to improve the light utilization efficiency and to prevent the device from being hindered in terms of thinness even if the circuit module 40 is built in.

[0079] In addition, the lighting device 1 according to this embodiment further includes a second light source 30, and the light guide plate 10 has a second end surface 12 onto which light emitted from the second light source 30 is incident, and the second end surface 12 faces away from the first end surface 11.

[0080] With this configuration, light can be incident on the light guide plate 10 from both end faces, the first end face 11 and the second end face 12, thereby increasing the amount of light (light output) emitted from the first main surface 13 of the light guide plate 10 and improving the uniformity of the light emitted from the first main surface 13 of the light guide plate 10.

[0081] Furthermore, in the lighting device 1 according to this embodiment, the light distribution of the lighting device 1 when only the first light source 20 of the first light source 20 and the second light source 30 is caused to emit light, and the light distribution of the lighting device 1 when only the second light source 30 of the first light source 20 and the second light source 30 is caused to emit light are each asymmetrical about the center line L passing through the center of the light guide plate 10 in the direction from the first end face 11 to the second end face 12.

[0082] This makes it possible to make the light distribution of the lighting device 1 when both the first light source 20 and the second light source 30 are made to emit light asymmetrical about the center line L passing through the center of the light guide plate 10 in the direction from the first end face 11 to the second end face 12 (X-axis direction). In other words, it is possible to make the light distribution of the lighting device 1 asymmetrical.

[0083] As a result, by changing the ratio between the amount of light emitted from the first light source 20 and the amount of light emitted from the second light source 30, the light distribution of the lighting device 1 can be changed.

[0084] In this case, in the lighting device 1 according to the present embodiment, when both the first light source 20 and the second light source 30 are made to emit light, the illuminance distribution of the lighting device 1 has only one peak.

[0085] This makes it possible to change the position of one peak in the illuminance distribution of the lighting device 1 on the floor surface by changing the ratio between the amount of light emitted from the first light source 20 and the amount of light emitted from the second light source 30.

[0086] In addition, the lighting device 1 according to this embodiment further includes a circuit module 40 having a control circuit that controls the ratio between the amount of light emitted from the first light source 20 and the amount of light emitted from the second light source 30.

[0087] This allows the circuit module 40 to control the ratio between the amount of light emitted from the first light source 20 and the amount of light emitted from the second light source 30, thereby changing the light distribution and illuminance distribution of the lighting device 1.

[0088] In this case, in the lighting device 1 according to the present embodiment, the circuit module 40 is located between the first inclined surface 14 a of the light guide plate 10 and the housing 50 .

[0089] With this configuration, the circuit module 40 can be stored in the groove formed on the second main surface 14 of the light guide plate 10 by the first inclined surface 14a, so that even if the circuit module 40 is built into the lighting device 1, the thickness of the lighting device 1 can be prevented from increasing.

[0090] Furthermore, in the lighting device 1 according to this embodiment, the second main surface 14 of the light guide plate 10 further has a second inclined surface 14b that reflects light incident from the second end surface 12, and the second inclined surface 14b is inclined so as to approach the first main surface 13 as it moves away from the second end surface 12.

[0091] This allows light incident from the second end face 12 of the light guide plate 10 to be reflected by the second inclined face 14b, thereby reducing the amount of light incident from the first end face 11 that travels straight from the second end face 12 to the first end face 11 without being able to exit from the first main surface 13, which is the light exit surface. This increases the amount of light that exits to the outside from the first main surface 13, which is the light exit surface, thereby further improving the light utilization efficiency.

[0092] Furthermore, in the lighting device 1 according to the present embodiment, the reflecting member 70 is provided on only one of the first inclined surface 14 a and the second inclined surface 14 b of the light guide plate 10 .

[0093] This makes it possible to make the light distribution and illuminance distribution of the illumination light from the lighting device 1 asymmetrical when both the first light source 20 and the second light source 30 are turned on.

[0094] In the lighting device 1 according to the present embodiment, the light guide plate 10 has a rectangular shape in plan view, and the direction from the first end face 11 to the second end face 12 is the widthwise direction of the light guide plate 10 .

[0095] With this configuration, the distance between the first end surface 11 where the light of the first light source 20 is incident and the second end surface 12 where the light of the second light source 30 is incident is shortened, which may result in an increase in the amount of light traveling straight from the first end surface 11 to the second end surface 12 of the light guide plate 10. However, by forming a first inclined surface 14a on the second main surface 14 of the light guide plate 10, as in the lighting device 1 of this embodiment, it is possible to reduce the amount of light traveling straight from the first end surface 11 to the second end surface 12 of the light guide plate 10, as described above.

[0096] (Modifications) Although the lighting device according to the present invention has been described above based on the embodiment, the present invention is not limited to the above embodiment.

[0097] For example, in the lighting device 1 in the above embodiment, the reflective member 70 is provided only on the first inclined surface 14a out of the first inclined surface 14a and the second inclined surface 14b formed on the second main surface 14 of the light guide plate 10, thereby making the light distribution and illuminance distribution of the illumination light of the lighting device 1 asymmetrical when the first light source 20 and the second light source 30 are made to emit light, but this is not limited to this.

[0098] Specifically, by providing the reflecting member 70 only on the second inclined surface 14b of the first inclined surface 14a and the second inclined surface 14b of the light guide plate 10, the light distribution and illuminance distribution of the illumination light from the lighting device 1 when the first light source 20 and the second light source 30 are activated may be made asymmetric. In other words, it is sufficient that the reflecting member 70 is provided on only one of the first inclined surface 14a and the second inclined surface 14b.

[0099] In addition, the light distribution and illuminance distribution of the illumination light from the lighting device 1 when the first light source 20 and the second light source 30 are illuminated may be made asymmetrical by a method other than providing a reflective member 70 on only one of the first inclined surface 14a and the second inclined surface 14b.

[0100] For example, as shown in FIG. 6 , the first inclined surface 14 a of the light guide plate 10 may be prism-processed to form a plurality of prisms 16 on the first inclined surface 14 a, thereby making the light distribution and illuminance distribution of the illumination light from the lighting device 1 asymmetric when the first light source 20 and the second light source 30 are activated. Each of the plurality of prisms 16 has a total-reflection control surface (side surface). Instead of forming the prisms 16 on the first inclined surface 14 a of the light guide plate 10, the prisms 16 may be formed on the second inclined surface 14 b of the light guide plate 10. Alternatively, the prisms 16 may be formed on both the first inclined surface 14 a and the second inclined surface 14 b. In other words, it is sufficient that the prism processing is performed on only one or both of the first inclined surface 14 a and the second inclined surface 14 b.

[0101] Alternatively, as in the lighting device 1B shown in Fig. 7 , the inclination angle of the first inclined surface 14a and the inclination angle of the second inclined surface 14b on the second main surface 14 of the light guide plate 10 may be made different, thereby making the light distribution and illuminance distribution of the illumination light of the lighting device 1 asymmetrical when the first light source 20 and the second light source 30 are activated. In this case, the thinnest part 15 of the light guide plate 10 is not located at the midpoint between the first end surface 11 and the second end surface 12. Also, in Fig. 7 , a reflecting member 70 may be formed on one of the first inclined surface 14a and the second inclined surface 14b, or a prism 16 may be formed on one or both of the first inclined surface 14a and the second inclined surface 14b.

[0102] Furthermore, in the lighting device 1 according to the above embodiment, the light distribution and illuminance distribution of the illumination light from the lighting device 1 when the first light source 20 and the second light source 30 are activated are asymmetrical. However, this is not limited to this. That is, the light distribution and illuminance distribution of the illumination light from the lighting device 1 when the first light source 20 and the second light source 30 are activated may be symmetrical. For example, as shown in FIG. 8 , the lighting device 1 shown in FIG. 1 may be configured such that the reflecting member 70 is not provided on either the first inclined surface 14 a or the second inclined surface 14 b. In this case, the first inclined surface 14 a is formed on the light guide plate 10, thereby improving light utilization efficiency. Furthermore, the circuit module 40 can be accommodated in the groove of the light guide plate 10 formed by the first inclined surface 14 a, thereby preventing the lighting device 1C from being hindered from being made thin even if the circuit module is built in.

[0103] Furthermore, in the above embodiment, the first light-emitting element 22 of the first light source 20 is an SMD element in which only one LED chip is mounted in a single package. However, this is not limited to this. For example, the first light-emitting element 22 may be a 2-in-1 type SMD element in which two LED chips are mounted in a single package. In this case, the single first light-emitting element 22 can be configured to change the color temperature in the range of 2700 K to 6500 K. This not only changes the luminous intensity distribution and illuminance distribution of the illumination light from the lighting device 1, but also changes the color temperature of the illumination light from the lighting device 1. In other words, the color of the illumination light from the lighting device 1 can be adjusted. Similarly, the second light-emitting element 32 of the second light source 30 may also be a 2-in-1 type SMD element in which two LED chips are mounted in a single package.

[0104] Furthermore, in the above embodiment, the color of the light emitted by the first light source 20 and the color of the light emitted by the second light source 30 are the same, but this is not limited to this. That is, the color of the light emitted by the first light source 20 and the color of the light emitted by the second light source 30 may be different. Specifically, the color temperature of the white light emitted by the first light source 20 and the color temperature of the white light emitted by the second light source 30 may be different. As an example, the color temperature of the white light emitted by the first light source 20 may be 2700 K, and the color temperature of the white light emitted by the second light source 30 may be 6500 K. In this way, by changing the current ratio between the first light source 20 and the second light source 30, the color temperature of the illumination light of the illumination device 1 can be changed in conjunction with changes in the light distribution and illuminance distribution of the illumination light of the illumination device 1.

[0105] Furthermore, in the above embodiment, the circuit module 40 divides the current between the first light source 20 and the second light source 30 at a predetermined current ratio while keeping the total current amount of the first light source 20 and the second light source 30 constant, but this is not limiting. In other words, the circuit module 40 may control the first light source 20 and the second light source 30 independently, rather than controlling them in conjunction with each other.

[0106] Furthermore, in the above embodiment, the diffusion film 60 is a milky white light diffusion film having a light diffusion material dispersed therein, but this is not limiting. For example, the diffusion film 60 may be formed by forming a milky white light diffusion film containing a light diffusion material on the surface (inner or outer surface) of a transparent film. Furthermore, the diffusion film 60 may be configured to have diffusive properties by performing a diffusion process rather than using a light diffusion material. For example, the diffusion film 60 may be configured to have light diffusive properties by performing a surface treatment such as embossing or laser processing to form minute irregularities (grain, microprisms, etc.) on the surface of the transparent film, or by printing a dot pattern on the surface of the transparent film.

[0107] Furthermore, in the above embodiment, the lighting device 1 includes the diffusion film 60, but this is not limiting. That is, the diffusion film 60 does not have to be provided on the first main surface 13 side of the light guide plate 10. In this case, the first main surface 13 of the light guide plate 10 becomes an exposed surface that is exposed to the outside. Therefore, the first main surface 13 becomes a light-emitting surface that emits pseudo-light when light guided within the light guide plate 10 is emitted to the outside.

[0108] Furthermore, in the above embodiment, the first light source 20 and the second light source 30 are both SMD-type LED modules, but this is not limiting. For example, the first light source 20 and the second light source 30 may be COB (chip on board) LED modules. For example, if the first light source 20 is a COB-type LED module, the first light emitting element 22, which is an LED chip, is directly mounted on the first substrate 21. In this case, for example, blue LED chips may be used as the first light emitting elements 22, and a plurality of these blue LED chips may be mounted in a row on the first substrate 21, and the blue LED chips may be individually or collectively sealed with a sealing member made of silicone resin containing a yellow phosphor.

[0109] In the above embodiment, the first light source 20 and the second light source 30 are configured to emit white light using a blue LED chip and a yellow phosphor, but this is not limiting. For example, the first light source 20 and the second light source 30 may be configured to emit white light by using a phosphor-containing resin containing red and green phosphors in combination with a blue LED chip, without using a yellow phosphor.

[0110] In the above embodiment, the first light-emitting element 22 of the first light source 20 and the second light-emitting element 32 of the second light source 30 are blue LED chips that emit blue light. However, this is not limited to this. For example, the first light-emitting element 22 and the second light-emitting element 32 may be LED chips that emit colors other than blue. For example, the first light-emitting element 22 and the second light-emitting element 32 may be LED chips that emit ultraviolet light. In this case, the phosphor particles may be a combination of phosphors that emit the three primary colors (red, green, and blue). Furthermore, although phosphors are used as wavelength conversion materials, wavelength conversion materials other than phosphors may also be used. For example, the wavelength conversion material may be a material that contains a substance that absorbs light of a certain wavelength and emits light of a different wavelength from the absorbed light, such as a semiconductor, a metal complex, an organic dye, or a pigment.

[0111] In the above embodiment, the first light source 20 and the second light source 30 are LED modules using LEDs, but the present invention is not limited to this. For example, the first light source 20 and the second light source 30 may use solid-state light-emitting elements other than LEDs, such as semiconductor lasers or organic electroluminescence (EL), or may be fluorescent lamps such as cold cathode fluorescent lamps (CCFL).

[0112] In addition, the present invention also includes forms obtained by applying various modifications to the above-mentioned embodiments that would occur to those skilled in the art, and forms realized by arbitrarily combining the components and functions of the above-mentioned embodiments within the scope of the present invention. Furthermore, the present invention also includes any combination of one or more components in each of the multiple claims described in the claims at the time of filing. Furthermore, when the dependent claims described in the claims at the time of filing are made into a multiple claim or multiple multiple claim that cites any multiple claims (for example, when a multiple claim or multiple multiple claim is made so that each claim cites all of its parent claims), all forms obtained by combining all claims included in the multiple claim or multiple multiple claim are also included in the present invention.

[0113] REFERENCE SIGNS LIST 1, 1A, 1B, 1C Illumination device 10 Light guide plate 11 First end surface 12 Second end surface 13 First main surface 14 Second main surface 14a First inclined surface 14b Second inclined surface 15 Thinnest part 16 Prism 20 First light source 30 Second light source 40 Circuit module 50 Housing 70 Reflective member

Claims

1. An illumination device comprising: a light guide plate; and a first light source that emits light to be incident on said light guide plate, wherein said light guide plate has a first end face into which light emitted from said first light source enters, a first main face from which light that entered said light guide plate exits to the outside of said light guide plate, and a second main face facing away from said first main face, wherein said second main face has a first inclined face that reflects light that entered said light guide plate from said first end face, and said first inclined face is inclined so as to approach said first main face with increasing distance from said first end face.

2. The lighting device according to claim 1, further comprising a second light source, wherein the light guide plate has a second end surface onto which light emitted from the second light source is incident, the second end surface facing away from the first end surface.

3. The lighting device according to claim 2, wherein the light distribution of the lighting device when only the first light source of the first light source and the second light source is made to emit light and the light distribution of the lighting device when only the second light source of the first light source and the second light source is made to emit light are asymmetrical about a center line passing through the center of the light guide plate in the direction from the first end face toward the second end face.

4. The lighting device according to claim 2, wherein the light distribution of the lighting device when both the first light source and the second light source are made to emit light is asymmetric about a center line passing through the center of the light guide plate in the direction from the first end face toward the second end face.

5. The lighting device according to claim 2, wherein the illuminance distribution of the lighting device when both the first light source and the second light source are turned on has only one peak.

6. The lighting device according to any one of claims 3 to 5, further comprising a circuit module having a control circuit that controls the ratio between the amount of light emitted from the first light source and the amount of light emitted from the second light source.

7. The lighting device according to claim 6, further comprising a housing that houses the light guide plate and the circuit module, the circuit module being positioned between the first inclined surface of the light guide plate and the housing.

8. The lighting device according to any one of claims 2 to 5, wherein the second main surface further has a second inclined surface that reflects light incident from the second end surface, and the second inclined surface is inclined so as to approach the first main surface with increasing distance from the second end surface.

9. The lighting device according to claim 8, wherein a reflecting member is provided on only one of the first inclined surface and the second inclined surface.

10. The lighting device according to claim 8, wherein prism processing is performed on only one of the first inclined surface and the second inclined surface.

11. The lighting device according to claim 8, wherein the inclination angle of the first inclined surface and the inclination angle of the second inclined surface are different.

12. The lighting device according to claim 8, wherein the connection portion between the first inclined surface and the second inclined surface is the thinnest part of the light guide plate, and the thinnest part is not located at a midpoint between the first end surface and the second end surface.

13. The lighting device according to any one of claims 2 to 5, wherein the light guide plate has a rectangular shape in a plan view, and the direction from the first end face toward the second end face is the short side direction of the light guide plate.

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