Lighting device

Abstract

The present application provides a kind of lighting device. According to an embodiment, the lighting device includes: light guide plate with upper surface, lower surface and light entrance surface;First light emitting part configured to radiate light in the first wavelength range;Second light emitting part configured to radiate light in the second wavelength range;And the third light emitting part configured to radiate light in the third wavelength range, the upper surface includes the first surface connected with the light entrance surface, the second surface parallel to the first surface between the first surface and the lower surface in the thickness direction, the third surface parallel to the second surface between the second surface and the lower surface in the thickness direction, and the fourth surface, the first surface, the second surface, the third surface and the fourth surface are arranged in the first direction in this order, the width of the first surface is smaller than the width of the second surface, the width of the second surface is smaller than the width of the third surface, the angle between the light entrance surface and the first surface is acute, the first light emitting part, the second light emitting part and the third light emitting part are opposite to the light entrance surface, and are arranged in the first direction in this order.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims priority based on Japanese Patent Application No. 2021-168182 filed on October 13, 2021, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] Embodiments of the present application relate to a lighting device. BACKGROUND

[0004] For example, a light emitting device in which a first semiconductor laser element that emits red light, a second semiconductor laser element that emits green light, and a third semiconductor laser element that emits blue light are integrally packaged is proposed. Such a light emitting device can be applied to a lighting device (backlight device) that illuminates, for example, a liquid crystal panel, and the like.

[0005] In recent years, the demand for thinning of liquid crystal display devices has further increased, and thinning of lighting devices is desired. SUMMARY

[0006] An object of an embodiment is to provide a lighting device that can be thinned.

[0007] According to an embodiment, a lighting device includes:

[0008] a light guide plate having an upper surface, a lower surface opposite to the upper surface, and a light incident surface connecting the upper surface and the lower surface; a first light emitting portion configured to radiate light in a first wavelength range; a second light emitting portion configured to radiate light in a second wavelength range different from the first wavelength range; and a third light emitting portion configured to radiate light in a third wavelength range different from the first wavelength range and the second wavelength range, the upper surface including a first surface connected to the light incident surface, a second surface parallel to the first surface and separated from the first surface and located between the first surface and the lower surface in a thickness direction of the light guide plate, a third surface parallel to the second surface and separated from the second surface and located between the second surface and the lower surface in the thickness direction, and a fourth surface, the first surface, the second surface, the third surface, and the fourth surface being arranged in this order in a first direction, a width of the first surface being smaller than a width of the second surface in terms of a width along the first direction, the width of the second surface being smaller than a width of the third surface in terms of the width along the first direction, the lower surface including a fifth surface opposite to and parallel to the fourth surface, an angle between the light incident surface and the first surface being an acute angle, the first light emitting portion, the second light emitting portion, and the third light emitting portion being opposite to the light incident surface and arranged in this order in the first direction.

[0009] According to the embodiment, it is possible to provide a lighting device capable of achieving miniaturization. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 is a diagram for explaining the lighting device IL of the embodiment.

[0011] Figure 2 is a diagram for explaining the lighting device IL of the embodiment. Figure 1 is a cross-sectional view of an example of the lighting device IL.

[0012] Figure 3 is a diagram for explaining the lighting device IL of the embodiment. Figure 2 is a plan view of the light guide plate 1.

[0013] Figure 4 is a diagram for explaining the total reflection surface.

[0014] Figure 5 is a cross-sectional view of an example of the lighting device IL.

[0015] Figure 6 is a plan view of an example of the lighting device IL.

[0016] Figure 7 is a diagram for explaining the lighting device IL of the embodiment. Figure 1 is a diagram of another example of the light guide plate 1.

[0017] Figure 8 is a diagram for explaining the lighting device IL of the embodiment. Figure 1 is a diagram of another example of the light guide plate 1.

[0018] Figure 9 is a diagram for explaining the lighting device IL of the embodiment. Figure 1 is a diagram of another example of the light guide plate 1.

[0019] Figure 10 is a diagram for explaining the lighting device IL of the embodiment. Figure 1 is a diagram of another example of the light guide plate 1. DETAILED DESCRIPTION

[0020] Hereinafter, an embodiment of the present application will be explained with reference to the accompanying drawings.

[0021] Further, the disclosure is only one example, and appropriate modifications that a person skilled in the art can easily think of while maintaining the gist of the application are of course included in the scope of the present application. In addition, in order to make the explanation more clear, the width, thickness, shape, and the like of each part of the drawings are sometimes schematically shown compared to the actual shape, but are only one example and do not limit the explanation of the present application. In addition, in the present specification and each drawing, a constituent element that has the same or similar function to a constituent element that has been explained with respect to the already appearing drawing is labeled with the same reference numeral, and sometimes the detailed explanation of the overlap is appropriately omitted.

[0022] Further, in the drawings, X-axis, Y-axis, and Z-axis orthogonal to one another are shown as needed for ease of understanding. The direction along the X-axis is referred to as the X direction or the first direction, the direction along the Y-axis is referred to as the Y direction or the second direction, and the direction along the Z-axis is referred to as the Z direction or the third direction. The plane defined by the X-axis and the Y-axis is referred to as the X-Y plane, and the plane defined by the X-axis and the Z-axis is referred to as the X-Z plane. The X-Y plane is referred to as plan view. The first direction X and the second direction Y correspond to directions parallel to the major surfaces of the light guide plate included in the illumination device, and the third direction Z corresponds to the thickness direction of the light guide plate.

[0023] Figure 1 FIG. 1 is a diagram for explaining the illumination device IL of the present embodiment.

[0024] The illumination device IL includes a light guide plate 1 and a light emitting device 2. Further, Figure 1 The light guide plate 1 and the light emitting device 2 shown are not accurate reflections of their shapes.

[0025] The light guide plate 1 will be described in detail later, but has an upper surface 11 opposed to the illumination object 3 in the third direction Z, a lower surface 12 opposed to the upper surface 11, and a light incident surface 13 connecting the upper surface 11 and the lower surface 12.

[0026] The upper surface 11 has a major surface (fourth surface to be described later) that is a flat surface extending in the first direction X. The lower surface 12 has a major surface (fifth surface to be described later) that is a flat surface extending in the first direction X. The region in which the pair of major surfaces are opposed to each other corresponds to an effective region AA of the light guide plate 1. The effective region AA is a region in which light propagating inside the light guide plate 1 is emitted. The region outside the effective region AA including the light incident surface 13 corresponds to a peripheral region PA of the light guide plate 1.

[0027] The light emitting device 2 is located on the end side of the light guide plate 1 along the first direction X, and is opposed to the light incident surface 13. The details of the light emitting device 2 will be described later, but the light emitting device 2 includes a light emitting portion configured to emit light in a prescribed wavelength range.

[0028] The illumination object 3 is, for example, a display panel. The display panel is, for example, a display panel (liquid crystal panel) including a liquid crystal layer, a display panel including an electrophoretic element, a display panel applying MEMS (micro electro mechanical systems), or the like. Such a display panel includes a display region DA in which an image is displayed, and a non-display region ND outside the display region DA. The display region DA is opposed to the effective region AA in the third direction Z. Further, the non-display region ND is opposed to the peripheral region PA.

[0029] In the case of a transmissive panel that displays images by selectively transmitting illumination light through the display panel, the illumination device IL functions as a backlight device. Conversely, in the case of a reflective panel that displays images by selectively reflecting illumination light, the illumination device IL functions as a headlight device.

[0030] A display device can be constructed by combining the lighting device IL of this embodiment with the display panel that serves as the object to be illuminated 3.

[0031] Figure 2 It is shown Figure 1 A cross-sectional view of an example of a lighting device IL is shown. Figure 2 The image shows a magnified view of the peripheral area PA of the light guide plate 1.

[0032] First, let's explain light guide plate 1.

[0033] The light guide plate 1 is a sheet made of resin such as polycarbonate or acrylic, but it can also be made of glass.

[0034] The upper surface 11 of the light guide plate 1 has a first surface 111, a second surface 112 separate from the first surface 111, a third surface 113 separate from the second surface 112, a fourth surface 114 adjacent to the third surface 113, a first connecting surface 115 connecting the first surface 111 and the second surface 112, and a second connecting surface 116 connecting the second surface 112 and the third surface 113. These surfaces 111 to 116 are all flat surfaces.

[0035] Surface 111, first connecting surface 115, second connecting surface 112, second connecting surface 116, third surface 113, and fourth surface 114 are arranged in this order in the first direction. Furthermore, in Figure 2 In the example shown, surface 3 113 and surface 4 114 are directly connected, but other connecting surfaces can also be provided between surface 3 113 and surface 4 114. Surface 111, first connecting surface 115, surface 2 112, second connecting surface 116, and surface 3 113 are located in the peripheral area PA. Surface 4 114 is located in the active area AA.

[0036] The first surface 111 is located at the topmost point and furthest from the lower surface 12 in the third direction (thickness direction of the light guide plate 1) Z among the surfaces constituting the upper surface 11. The first surface 111 is the surface furthest from the effective region AA in the first direction X among the surfaces constituting the upper surface 11. Alternatively, the first surface 111 is located at one end of the peripheral region PA in the first direction X. The first surface 111 has a width W1 along the first direction X.

[0037] The second surface 112 is located between the first surface 111 and the lower surface 12 in the third direction Z. The second surface 112 has a width W2 along the first direction X. The width W2 is larger than the width W1 (W2 > W1).

[0038] The third surface 113 is located between the second surface 112 and the lower surface 12 in the third direction Z. The third surface 113 is located at the other end of the peripheral region PA in the first direction X. The third surface 113 has a width W3 along the first direction X. The width W3 is larger than the width W2 (W3 > W2).

[0039] The first surface 111, the second surface 112, and the third surface 113 are parallel to each other. The fourth surface 114 is a surface parallel to the XY plane. When the fourth surface 114 is set as the reference surface, the first surface 111, the second surface 112, and the third surface 113 have the same inclination γ. In one example, the inclination γ is greater than 0° and less than 15°. When the inclination γ is 0°, the third surface 113 and the fourth surface 114 form a continuous, identical plane.

[0040] Furthermore, when the tilt angle γ is 0°, the angle θ1 between the third surface 113 and the fourth surface 114 is 180°. The greater the tilt angle γ becomes, the smaller the angle θ1 becomes. In one example, the angle θ1 is greater than 165° and less than 180°.

[0041] The first connecting surface 115 and the second connecting surface 116 are inclined surfaces that are tilted relative to the fourth surface 114 when the fourth surface 114 is set as the reference surface. The first connecting surface 115 and the second connecting surface 116 are parallel to each other. Alternatively, the first connecting surface 115 and the second connecting surface 116 may not be parallel to each other.

[0042] The lower surface 12 of the light guide plate 1 has a fifth surface 125 and a connecting surface 126 that connects the fifth surface 125 and the light incident surface 13. Each of these surfaces 125 to 126 is a flat surface.

[0043] The fifth surface 125 is opposite to the fourth surface 114 in the third direction Z. The fifth surface 125 is a surface parallel to the XY plane and parallel to the fourth surface 114. The fifth surface 125 extends throughout the effective area AA and the surrounding area PA. The light guide plate 1 has a thickness T1 in the effective area AA along the third direction Z between the fourth surface 114 and the fifth surface 125.

[0044] In the surrounding area PA, the fifth surface 125 is opposite to the third surface 113 and the second connecting surface 116 in the third direction Z. The end 125E of the fifth surface 125, or the boundary between the fifth surface 125 and the connecting surface 126, is located between the second surface 112 and the third surface 113 in the first direction X. In addition, the end 125E is opposite to the second connecting surface 116 in the third direction Z.

[0045] The light-incident surface 13 of the light guide plate 1 is a flat surface, or an inclined surface that is tilted relative to the fourth surface 114, the fifth surface 125, or the XY plane. The light-incident surface 13 is connected to the first surface 111 and the connecting surface 126. The connection position between the light-incident surface 13 and the first surface 111 is located at one end of the peripheral region PA in the first direction X. The angle θ2 formed by the light-incident surface 13 and the first surface 111 is an acute angle (less than 90°). The light-incident surface 13 is opposite to the first surface 111, the first connecting surface 115, and the second surface 112 in the third direction Z.

[0046] The incident light surface 13 has a width W13 along the first direction X. The width W13 is larger than the thickness T1 (W13 > T1). The thickness T1 is 1.5 mm or less, and in one example it is 1.0 mm.

[0047] Next, the light-emitting device 2 will be described.

[0048] The light-emitting device 2 includes a first light-emitting portion 21, a second light-emitting portion 22, and a third light-emitting portion 23. The first light-emitting portion 21, the second light-emitting portion 22, and the third light-emitting portion 23 are mounted on a circuit board 20 shown in dashed lines. The first light-emitting portion 21, the second light-emitting portion 22, and the third light-emitting portion 23 are positioned opposite to the light-incident surface 13 and arranged in this order in the first direction X. Furthermore, each of the first light-emitting portion 21, the second light-emitting portion 22, and the third light-emitting portion 23 is configured to radiate light toward the light-incident surface 13. Specifically, as described below.

[0049] The first light-emitting part 21 is configured to emit light in a first wavelength range (first emitted light). In one example, the first wavelength range is the red wavelength range, and the first light-emitting part 21 has a first semiconductor laser element that emits red light.

[0050] The second light-emitting part 22 is configured to emit light in a second wavelength range (second emitted light). The second wavelength range is different from the first wavelength range. In one example, the second wavelength range is the green wavelength range, and the second light-emitting part 22 has a second semiconductor laser element that emits green light.

[0051] The third light-emitting unit 23 is configured to emit light in a third wavelength range (third emitted light). The third wavelength range is different from the first wavelength range and the second wavelength range. In one example, the third wavelength range is the blue wavelength range, and the third light-emitting unit 23 has a third semiconductor laser element that emits blue light.

[0052] The distance D along the light-incident surface 13 from the first light-emitting part 21 to the third light-emitting part 23 is greater than the thickness T1 of the light guide plate 1 (D > T1).

[0053] Furthermore, the light-emitting device 2 is not limited to having three light-emitting parts; it may also have two or four or more light-emitting parts. Additionally, the combination of colors of the light emitted by each light-emitting part is not limited to red, green, and blue. For example, it may use one or two of red, green, and blue, or it may include colors different from red, green, and blue.

[0054] Next, we will further explain page 111, page 212, and page 313 in detail.

[0055] The first surface 111 is located on the first optical path PT1 of the principal ray in the first emitted light emitted from the first light-emitting part 21. In addition, the first optical path PT1 is orthogonal to the incident surface 13. The first emitted light includes diffuse light that is diffused relative to the principal ray at a divergence angle δ, in addition to the principal ray.

[0056] The first surface 111 is a total reflection surface configured to totally reflect the first radiated light. That is, the first surface 111 has an inclination angle γ that is set to totally reflect almost all of the first radiated light, including the main ray and the diffuse ray.

[0057] The second surface 112 is located on the second optical path PT2 of the principal ray in the second emitted light from the second light-emitting part 22. The second optical path PT2 is orthogonal to the incident surface 13 and parallel to the first optical path PT1. The second emitted light includes diffuse light that is diffused relative to the principal ray at a divergence angle δ, in addition to the principal ray. The length of the second optical path PT2 from the second light-emitting part 22 to the second surface 112 is longer than the length of the first optical path PT1 from the first light-emitting part 21 to the first surface 111.

[0058] The second surface 112 is a total reflection surface configured to totally reflect the second emitted light. That is, the second surface 112 has an inclination angle γ that is set to totally reflect almost all of the second emitted light, including the main ray and the diffuse ray. As described above, the second surface 112 is parallel to the first surface 111 and has the same inclination angle γ as the first surface 111.

[0059] The third surface 113 is located on the third optical path PT3 of the principal ray in the third emitted light from the third light-emitting part 23. The third optical path PT3 is orthogonal to the incident surface 13 and parallel to the second optical path PT2. The third emitted light includes diffuse light that is diffused relative to the principal ray at a divergence angle δ, in addition to the principal ray. The length of the third optical path PT3 from the third light-emitting part 23 to the third surface 113 is longer than the length of the second optical path PT2 from the second light-emitting part 22 to the second surface 112.

[0060] The third surface 113 is a total reflection surface configured to totally reflect the third emitted light. That is, the third surface 113 has an inclination angle γ that is set to totally reflect almost all of the third emitted light, including the main ray and the diffuse ray. As described above, the third surface 113 is parallel to the first surface 111 and has the same inclination angle γ as the first surface 111.

[0061] Figure 3 yes Figure 2 The top view of the light guide plate 1 is shown.

[0062] On the upper surface 11, the first surface 111, the second surface 112, the third surface 113, the first connecting surface 115, and the second connecting surface 116 are each formed into a rectangular shape extending along the second direction Y when viewed from above. The fourth surface 114 has the largest area on the upper surface 11.

[0063] Furthermore, the connecting surface 126 and the light-incident surface 13 of the lower surface 12 are also formed into rectangular shapes extending along the second direction Y when viewed from above. The fifth surface 125 has the largest area on the lower surface 12.

[0064] Figure 4 This diagram is used to illustrate a total internal reflection surface. Here, the tilt angle γ is explained using the third surface 113 of the total internal reflection surface as an example. The angle of the light path described below is considered to be the angle between the fourth surface 114 and the light path.

[0065] As described above, the third emitted light from the light-incident surface 13 to the light guide plate 1 includes a principal ray B0 and diffused rays B1 and B2 diffused at a divergence angle δ. The angle of the optical path of the principal ray B0 from the light-incident surface 13 to the third surface 113 is set as α0, the angle of the optical path of the diffused light B1 is set as α0+δ, and the angle of the optical path of the diffused light B2 is set as α0-δ. The angle of the optical path of the principal ray B0 reflected from the third surface 113 is set as α, the angle of the optical path of the diffused light B1 is set as α+δ, and the angle of the optical path of the diffused light B2 is set as α-δ.

[0066] In order for the third emitted light to be totally reflected by the third surface 113, the angle β between the light path of the diffuse light B1 and the third surface 113 must satisfy the total reflection condition shown below.

[0067] β<90°-θc…(1)

[0068] Here, θc is the critical angle. When the refractive index of air is set to 1 and the refractive index of light guide plate 1 is set to 1.5, the critical angle θc is 41.8°.

[0069] Β is equal to (α+δ+γ).

[0070] As an example, with α = 26.5° and δ = 6.5°, the range of tilt γ is shown below.

[0071] γ < 15.2°

[0072] In other words, the preferred tilt angle γ is less than 15°.

[0073] Furthermore, at this point, α+δ is 33° and α-δ is 20°.

[0074] The relationship between α0 and α is shown below.

[0075] α0=α+2γ

[0076] With γ = 9°, α0 = 44.5°, α0 + δ = 51°, α0 - δ = 38°, and β = 42°.

[0077] When the incident surface 13 is orthogonal to the optical path of the principal ray B0, the tilt of the incident surface 13 is... The angle is 45.5°. In addition, the angle θ2 between the first surface 111 and the incident surface 13 is 54.5°.

[0078] Figure 5 This is a cross-sectional view showing an example of a lighting device IL. Figure 5 In the example shown, the tilt angle γ of the first face 111, the second face 112, and the third face 113 is 9°.

[0079] The emitted light (R) from the first light-emitting unit 21, the emitted light (G) from the second light-emitting unit 22, and the emitted light (B) from the third light-emitting unit 23 are incident on the light guide plate 1 via the light-incident surface 13. The emitted light, including the principal ray R0 and diffuse rays R1 and R2, is reflected by the first surface 111. The emitted light, including the principal ray G0 and diffuse rays G1 and G2, is reflected by the second surface 112. The emitted light, including the principal ray B0 and diffuse rays B1 and B2, is reflected by the third surface 113. The reflected light of each color propagates inside the light guide plate 1 while being reflected by the fifth surface 125 and the fourth surface 114. Light that does not meet the total internal reflection condition within the light propagating inside the light guide plate 1 is emitted from the fourth surface 114 in the effective area AA.

[0080] Figure 6 This is a top view showing an example of a lighting device IL.

[0081] When viewed from above, in the peripheral area PA of the light guide plate 1, the emitted light R from the first light-emitting part 21, the emitted light G from the second light-emitting part 22, and the emitted light B from the third light-emitting part 23 mix together along the first direction X to form illumination light. Additionally, in the effective area AA, the illumination light emitted from adjacent light-emitting devices 2 in the second direction Y propagates along the first direction X and diffuses in the second direction Y, mixing together.

[0082] In addition, Figure 6 The diagram schematically illustrates the diffusion of radiated light R, radiated light G, and radiated light B, but the degree of diffusion or directionality in the XY plane is not limited to all three being identical. When the directions of radiated light R, radiated light G, and radiated light B differ, it is preferable to position the emitting portion of the light with high directionality (less prone to diffusion) away from the effective region AA, and to position the emitting portion of the light with low directionality (easier to diffuse) closer to the effective region AA. That is, in Figure 6 In the example shown, a combination can be applied in which the light emitted from the first light-emitting part 21 has high directivity and the light emitted from the third light-emitting part 23 has low directivity.

[0083] According to this lighting device IL, compared with the edge lighting arrangement where the first light-emitting part 21, the second light-emitting part 22, and the third light-emitting part 23 are arranged in the second direction Y and the light guide plate 1 are positioned opposite each other, the distance along the first direction X required for mixing light of different wavelengths can be shortened. That is, the length along the first direction X of the peripheral region PA can be shortened.

[0084] Furthermore, according to the above-mentioned lighting device IL, compared with the other edge lamp arrangement in which the first light-emitting part 21, the second light-emitting part 22, and the third light-emitting part 23 are arranged in the third direction Z and the side of the light guide plate 1 are opposite each other, the thickness of the light guide plate 1 can be reduced.

[0085] This enables the miniaturization of the lighting device IL.

[0086] Based on this, the first surface 111, the second surface 112, and the third surface 113 are total reflective surfaces. Therefore, reflective layers for reflecting various colors of emitted light are not required on the first surface 111, the second surface 112, and the third surface 113. As a result, the cost of the lighting device IL can be reduced.

[0087] Figure 7 It is shown Figure 1 A diagram showing another example of the light guide plate 1.

[0088] Figure 7 The light guide plate 1 shown in the example is...Figure 5 Compared to the light guide plate 1 shown, the difference lies in the tilt angle γ, which is 0°. That is, the first surface 111, the second surface 112, and the third surface 113 are parallel to the fourth surface 114, which serves as a reference surface. Furthermore, the third surface 113 and the fourth surface 114 form a continuous, identical plane. The angle θ1 formed by the third surface 113 and the fourth surface 114 is 180°.

[0089] Surface 111 is a total internal reflection surface that reflects the radiated light, including the principal ray R0 and the diffuse rays R1 and R2. Surface 212 is a total internal reflection surface that reflects the radiated light, including the principal ray G0 and the diffuse rays G1 and G2. Surface 313 is a total internal reflection surface that reflects the radiated light, including the principal ray B0 and the diffuse rays B1 and B2. The light paths of the principal rays R0, G0, and B0 are parallel to each other.

[0090] The incident surface 13 is tilted in a manner that is orthogonal to the respective optical paths of the principal rays R0, G0, and B0.

[0091] With the angle α of the principal ray after total internal reflection being 26.5°, the angle α0 of the principal ray from the incident surface 13 to the total internal reflection surface is also 26.5°. The tilt of the incident surface 13... The angle is 63.5°. In addition, the angle θ2 between the first surface 111 and the incident surface 13 is 63.5°.

[0092] Compare Figure 5 The example shown has light guide plate 1 and Figure 7 As can be seen from the example light guide plate 1, the smaller the tilt angle γ becomes, the larger the width W1 of the first surface 111, the width W2 of the second surface 112, and the width W3 of the third surface 113 become, and the larger the angle θ2 becomes.

[0093] Figure 8 It is shown Figure 1 A diagram showing another example of the light guide plate 1. Figure 8 Cross-sections of several light guide plates 1 with different tilt angles γ are shown, but the first side is omitted. Here, light guide plates 1 with tilt angles γ of 15°, 9°, 5°, 0°, and -5° are shown respectively.

[0094] The shapes of each light guide plate 1 shown in the figure are optimized to satisfy the following conditions: the radiated light R reflected by the first surface reaches the fifth surface 125, the radiated light G is reflected by the second surface 112 and the reflected light reaches the fifth surface 125, and the radiated light B is reflected by the third surface 113 and the reflected light reaches the fifth surface 125.

[0095] Comparing the light guide plate 1 with the optimized shape obtained under the above conditions, a larger tilt angle γ results in a smaller PA in the surrounding area. Furthermore, it is known that a smaller tilt angle γ leads to a larger thickness T2 of PA in the surrounding area. Based on these observations, the tilt angle γ is preferably 0° or greater.

[0096] Figure 9 It is shown Figure 1 A diagram showing another example of the light guide plate 1. Figure 9 Several cross-sections of the light guide plate 1 are shown, but the first side is omitted.

[0097] exist Figure 9 In the example shown, the divergence angles δ of the emitted light from the first light-emitting part 21, the second light-emitting part 22, and the third light-emitting part 23 are different from each other. In this case, the tilt angle γ of the first surface 111, the second surface 112, and the third surface 113 is determined based on the maximum divergence angle δ.

[0098] Here, we illustrate the case where the divergence angle δ of the emitted light R is the largest and the divergence angle δ of the emitted light G is the smallest. In this case, the tilt angle γ is determined based on the divergence angle δ of the emitted light R. In one example, the divergence angle δ of the emitted light G is 6.5°, the divergence angle δ of the emitted light B is 6.7°, and the divergence angle δ of the emitted light R is 8.8°.

[0099] With the refractive index of air set to 1, the refractive index of light guide plate 1 set to 1.5, the critical angle θc set to 41.8°, α set to 26.5°, and δ set to 8.8°, based on the reference... Figure 4 The range of the inclination γ of the relation (1) is shown below.

[0100] γ < 12.9°

[0101] Figure 9 The shapes of each light guide plate 1 shown are optimized to satisfy the following conditions: the tilt angle γ satisfies the condition of less than 12.9°, the radiated light R reflected by the first surface reaches the fifth surface 125, the radiated light G is reflected by the second surface 112 and the reflected light reaches the fifth surface 125, and the radiated light B is reflected by the third surface 113 and the reflected light reaches the fifth surface 125.

[0102] exist Figure 9 In the example shown above, the configuration is such that the first light-emitting part 21 emits light R in the first wavelength range of the red wavelength range, the second light-emitting part 22 emits light B in the second wavelength range of the blue wavelength range, and the third light-emitting part 23 emits light G in the third wavelength range of the green wavelength range.

[0103] exist Figure 9In the example shown in the middle section, the first light-emitting part 21 emits light B in the first wavelength range of blue wavelength, the second light-emitting part 22 emits light G in the second wavelength range of green wavelength, and the third light-emitting part 23 emits light R in the third wavelength range of red wavelength.

[0104] exist Figure 9 In the example shown in the lower paragraph, the first light-emitting part 21 emits light B in the first wavelength range of blue wavelength, the second light-emitting part 22 emits light R in the second wavelength range of red wavelength, and the third light-emitting part 23 emits light G in the third wavelength range of green wavelength.

[0105] Comparing the light guide plate 1 with the optimized shape obtained under the above conditions, the divergence angle of the emitted light from the second light-emitting part 22 is larger than the divergence angle of the light emitted from the first light-emitting part 21 and the divergence angle of the light emitted from the third light-emitting part 23. Figure 9 In the example shown in the next paragraph, it is possible to reduce the surrounding area PA and to thin the thickness T1 in the effective area AA.

[0106] Figure 10 It is shown Figure 1 A diagram showing another example of the light guide plate 1. Figure 10 Several cross-sections of the light guide plate 1 are shown, but the first side is omitted.

[0107] exist Figure 10 The example shown illustrates the case where the divergence angle δ of the emitted light R is the largest and the divergence angle δ of the emitted light B is the smallest. In this case, the tilt angle γ is determined based on the divergence angle δ of the emitted light R. In one example, the divergence angle δ of the emitted light G is 7.5°, the divergence angle δ of the emitted light B is 5°, and the divergence angle δ of the emitted light R is 10°.

[0108] With the refractive index of air set to 1, the refractive index of light guide plate 1 set to 1.5, the critical angle θc set to 41.8°, α set to 26.5°, and δ set to 10°, based on the reference... Figure 4 The range of the inclination γ of the relation (1) is shown below.

[0109] γ < 11.7°

[0110] Figure 10 The shapes of each light guide plate 1 shown are optimized to satisfy the following conditions: the tilt angle γ is 11°, the radiated light R reflected by the first surface reaches the fifth surface 125, the radiated light G is reflected by the second surface 112 and the reflected light reaches the fifth surface 125, and the radiated light B is reflected by the third surface 113 and the reflected light reaches the fifth surface 125.

[0111] exist Figure 10 In the example shown above, the configuration is such that the first light-emitting unit 21 emits light R in the first wavelength range of the red wavelength range, the second light-emitting unit 22 emits light G in the second wavelength range of the green wavelength range, and the third light-emitting unit 23 emits light B in the third wavelength range of the blue wavelength range.

[0112] exist Figure 10 In the example shown in the middle section, the first light-emitting part 21 emits light B in the first wavelength range of blue wavelength, the second light-emitting part 22 emits light G in the second wavelength range of green wavelength, and the third light-emitting part 23 emits light R in the third wavelength range of red wavelength.

[0113] exist Figure 10 In the example shown in the lower paragraph, the first light-emitting part 21 emits light B in the first wavelength range of blue wavelength, the second light-emitting part 22 emits light R in the second wavelength range of red wavelength, and the third light-emitting part 23 emits light G in the third wavelength range of green wavelength.

[0114] Comparing the light guide plate 1 with the optimized shape obtained under the above conditions, the divergence angle of the emitted light from the second light-emitting part 22 is larger than the divergence angle of the light emitted from the first light-emitting part 21 and the divergence angle of the light emitted from the third light-emitting part 23. Figure 10 (As shown in the example below) it is possible to reduce the thickness of the surrounding area PA and also to thin the thickness T1 in the effective area AA.

[0115] According to the above embodiment, a lighting device capable of miniaturization can be provided.

[0116] Any lighting device that can be implemented by those skilled in the art based on the lighting device described above as an embodiment of the present invention, with appropriate modifications, is within the scope of the present invention as long as it contains the spirit of the present invention.

[0117] Within the scope of the present invention, various modifications will be conceived by those skilled in the art, and these modifications should be understood to fall within the scope of the present invention. For example, any technical content obtained by adding, removing, or designing constituent elements appropriately relative to the above embodiments, or by adding, omitting, or changing processes or conditions, is included within the scope of the present invention as long as it possesses the spirit of the present invention.

[0118] Furthermore, any other effects resulting from the forms described in the above embodiments should be understood as being brought about by the present invention, based on the explicit technical content described in this specification or the technical content that can be appropriately conceived by those skilled in the art.

Claims

1. A lighting device comprising: A light guide plate having an upper surface, a lower surface opposite to the upper surface, and a light incident surface connecting the upper surface and the lower surface; It is configured as a first light-emitting part that emits light in the first wavelength range; A second light-emitting part is configured to emit light in a second wavelength range different from the first wavelength range; and A third light-emitting part is configured to emit light in a third wavelength range that is different from the first wavelength range and the second wavelength range. The upper surface includes a first surface connected to the light incident surface, a second surface separated from the first surface and located between the first surface and the lower surface in the thickness direction of the light guide plate and parallel to the first surface, a third surface separated from the second surface and located between the second surface and the lower surface in the thickness direction and parallel to the second surface, and a fourth surface connected to the third surface. The first surface, the second surface, the third surface, and the fourth surface are arranged sequentially in the first direction, starting from the connection position between the first surface and the incident light surface. Regarding the width along the first direction, the width of the first surface is smaller than the width of the second surface, and the width of the second surface is smaller than the width of the third surface. The lower surface includes a fifth surface that is opposite to and parallel to the fourth surface. The angle between the incident light surface and the first surface is an acute angle. The first light-emitting part, the second light-emitting part, and the third light-emitting part are opposite to the light-incident surface, and the first light-emitting part, the second light-emitting part, and the third light-emitting part are arranged sequentially in the first direction, starting from the connection position between the first surface and the light-incident surface.

2. The lighting device according to claim 1, wherein, When the fourth surface is set as the reference surface, the inclination of the first surface, the second surface, and the third surface is 15° or less.

3. The lighting device according to claim 2, wherein, The tilt angle is 0° or greater.

4. The lighting device according to claim 1, wherein, The upper surface also includes a first connecting surface that connects the first surface and the second surface, and a second connecting surface that connects the second surface and the third surface and is parallel to the first connecting surface.

5. The lighting device according to claim 1, wherein, The end of the fifth surface is located between the second and third surfaces in the first direction.

6. The lighting device according to claim 5, wherein, The light-incident surface is opposite to the first surface and the second surface in the thickness direction. The fifth surface is opposite to the third surface in the thickness direction.

7. The lighting device according to claim 1, wherein, The first surface is located on the first optical path of the main ray emitted from the first light-emitting part. The second surface is located on the second optical path of the main ray emitted from the second light-emitting part. The third surface is located on the third optical path of the main ray emitted from the third light-emitting part.

8. The lighting device according to claim 7, wherein, The first optical path, the second optical path, and the third optical path are parallel to each other.

9. The lighting device according to claim 1, wherein, The first surface is configured as a total internal reflection surface that will totally reflect the light emitted from the first light-emitting part. The second surface is configured as a total internal reflection surface that will totally reflect the light emitted from the second light-emitting part. The third surface is configured to be a total reflection surface that reflects the light emitted from the third light-emitting part.

10. The lighting device according to claim 1, wherein, The width along the light-incident surface from the first light-emitting part to the third light-emitting part is greater than the thickness between the fourth and fifth surfaces.

11. The lighting device according to claim 10, wherein, The thickness is less than 1.5 mm.

12. The lighting device according to claim 1, wherein, The divergence angle of the light emitted from the second light-emitting part is larger than that of the light emitted from the first light-emitting part and the light emitted from the third light-emitting part.

13. The lighting device according to claim 12, wherein, The second wavelength range is the red wavelength range.

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