JP3594578B2 - LCD lighting device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid crystal lighting device that illuminates a liquid crystal display device.
[0002]
[Prior art]
2. Description of the Related Art Liquid crystal display devices are widely used in many fields. As is well known, a liquid crystal display device used in a liquid crystal display device does not have a function of emitting light by itself, so that light is emitted by a liquid crystal lighting device. It is necessary.
For example, as a liquid crystal lighting device, a light guide plate is provided so as to face a surface of a liquid crystal display element, and a light emitting diode is disposed opposite to an incident end face of a side portion of the light guide plate, and a light emitting diode is disposed in parallel with a side end face of the light guide plate. A light source device attached to the end of an elongated light guide rod extending in the direction is disposed, and the light emitted from the light emitting diode is reflected or refracted in the light guide rod, and the surface of the light guide rod on the light guide plate side. From the light guide plate toward the incident surface of the light guide plate.
[0003]
Incidentally, the liquid crystal display element is formed by attaching a polarizer to a liquid crystal material sealed between transparent plates, and the polarizer has a transmission axis (an axis including a vibration plane of light that can pass through). . This transmission axis is not usually parallel to the light incident side end face of the light guide plate (= one side end face of the liquid crystal display device).
However, in a conventional liquid crystal lighting device, light having a vibrating surface that matches the transmission axis of a polarizer attached to the liquid crystal display element is not guided, and light emitted from the liquid crystal lighting device is not always sufficiently used. Did not.
[0004]
[Problems to be solved by the invention]
In view of the above problems, the present invention provides a liquid crystal lighting device that illuminates a liquid crystal display surface with light emitted from a light source device through a light guide plate. The purpose is to make the light easy to pass through.
[0005]
[Means for Solving the Problems]
According to the first aspect of the present invention, light emitted from the light source device is guided inside from the light incident side end face of the light guide plate disposed outside one surface of the liquid crystal display element, and is directed to the liquid crystal display element of the light guide plate. A liquid crystal lighting device for illuminating the liquid crystal display device by reflecting the light inside the first surface and emitting the light from the second surface near the liquid crystal display device of the light guide plate,
When X, Y, and Z are three orthogonal directions,
The liquid crystal display element is formed by sandwiching a liquid crystal material between transparent plates and extends in the XY directions, and a light guide plate side is provided with a polarizer extending in the XY directions. The polarizer has a transmission axis inclined in the XY plane from the Y direction. Has,
The light guide plate has a light incident side end surface that extends elongated in the XZ direction, a first surface and a second surface that extend in the XY direction, a prism array formed on the first surface, and a peak and a valley of the prism array. The line extends in the X direction,
The light source device comprises: a light guide plate side face which is elongated in the X direction and is elongated in the Z direction and is opposed to the light incident side end face of the light guide plate; an anti-light guide plate side surface parallel to the light guide plate side surface; A light guide rod having two surfaces extending in the X direction and elongated in the Y direction so as to be long in the X direction and having a light emitting diode attached to at least one of the two end surfaces in the X direction;
The light guide rod has a plurality of first inclined surfaces extending from the light guide plate side toward the light guide plate side, and the first inclined surface is closer to the light emitting diode on the opposite light guide plate side and farther from the light emitting diode on the light guide plate side, The angle α of the first inclined surface from the X direction on the counter light guide plate side is selected as an angle such that light emitted vertically from the light guide plate side surface toward the light source side end surface of the light guide plate is only S-wave light,
The light guide rod is formed of a first material, the refractive index of the first material is n ₁ , the first material is in contact with the light guide rod with the first inclined surface as a boundary, and the first inclined surface extends from the first material toward the first inclined surface. when the refractive index of the second material through which light transmitted was n ₂ a, tan (90 -α) = liquid crystal lighting apparatus characterized by being selected so as to satisfy n ₂ / n ₁ is provided You.
In the liquid crystal lighting device configured as described above, the light perpendicular to the incident end face of the light guide plate is only S-wave light.
[0007]
According to the invention of claim 2, in the invention of claim 1 , the first substance forming the light guide rod has a refractive index n ₁ of 1.49, the second substance is air, and α is 32 degrees. A liquid crystal lighting device is provided.
[0008]
According to the third aspect of the present invention, in the first aspect of the present invention, the tip of the first inclined surface on the side of the light guide plate in the Y direction is on the side of the light guide plate on the side of the light guide plate, and the tip of the light guide plate in the Y direction is light. A liquid crystal lighting device is provided, wherein a second inclined surface reaching the side of the light guide plate opposite to the light guide plate is coupled to the light guide plate end at the inside of the guide rod.
[0009]
According to a fourth aspect of the present invention, in the third aspect of the invention, the depth of the joint between the first inclined surface and the second inclined surface from the side surface of the light guide plate increases as the distance from the light emitting diode increases. A liquid crystal lighting device is provided.
[0010]
According to a fifth aspect of the present invention, in the first aspect, the light emitting diode is attached to only one of the two ends of the light guide rod in the X direction, and the other end is provided via a λ / 4 plate. A reflector is attached,
The first inclined surface includes a pair of a diode-side first inclined surface on the light emitting diode side and a first diode-side inclined surface opposite to the diode-side first inclined surface, and the first diode-side inclined surface and the opposite diode side. A liquid crystal lighting device is provided, wherein a second substance is interposed between the first inclined surfaces.
[0011]
According to the invention of claim 6, in the invention of claim 5 , the tip of the first inclined surface on the side of the light guide plate in the Y direction is on the side of the light guide plate of the light guide rod, and the end of the light guide plate on the side of Y in the light direction. A liquid crystal lighting device is provided, which is provided on a side surface of a light guide plate of a guide rod.
[0012]
According to the invention of claim 7, in the invention of claim 5 , there is a second inclined surface in addition to the first inclined surface, and the second inclined surface is a pair of diode-side second inclined surfaces on the light emitting diode side. And a diode-side second inclined surface facing the diode-side second inclined surface, wherein a second substance is interposed between the diode-side second inclined surface and the anti-diode-side second inclined surface. A liquid crystal lighting device is provided.
[0013]
According to the invention of claim 8, in the invention of claim 7 , the diode-side first inclined surface and the opposite diode-side second inclined surface, and the diode-side first inclined surface and the diode-side second inclined surface, respectively, And a liquid crystal lighting device connected inside the light guide rod.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a liquid crystal lighting device of the present invention will be described with reference to the accompanying drawings. Each drawing is partially exaggerated for the sake of explanation.
FIG. 1 is a schematic diagram for explaining a liquid crystal lighting device according to a first embodiment of the present invention, in which X and Y directions are defined as shown in the figure, and a Z direction is a direction perpendicular to the plane of the figure. Defined in
[0015]
FIG. 1 shows a light source device 10 and a light guide plate 20. The light source device 10 includes a light guide rod 11 and light emitting diodes 12 attached to both ends of the light guide rod 11 in the X direction. The light guide rod 11 is formed of a transparent resin such as acrylic, a refractive index n ₁ is 1.49.
A triangular groove 100 is formed on the side surface 11a of the light guide rod 11 as shown in the drawing. The grooves 100 are formed at the same interval c, but the groove depth d increases as the distance from the light emitting diode increases, and is set to be deepest at the center.
On the other hand, a prism array 22 including a large number of prisms 23 is formed on the surface of the light guide plate 20, and peaks 23a and valleys 23b of the prisms 23 extend in the X direction.
[0016]
In this embodiment, the pitch P is 0.3 mm, and the groove depth d satisfies the following equation.
d = 0.015 × N ² + 0.5 × N + 15 (N = 1 to 83)
= 0.015 × {166- (N-1)} ² + 0.5 × {166- (N-1)} + 15 (N = 84 to 166) [unit: μm]
However, 166 grooves 100 are formed, N is the number of the groove 100, the number of the left end groove 100 is 1, and the number of the right end groove is 166. FIG. 2 is a diagram showing a change in the depth d of the groove 100. The groove depth d is 15.5 μm at both ends and 159.8 μm at the center.
[0017]
The group of grooves 100 shown on the left side of the center and the group of grooves 100 shown on the right side of the center are similar but different in size.
The groove 100 has a first inclined surface 110 inclined inwardly at an angle α from a position near the light-emitting diode 12 on the side of the light guide rod 11 of the light guide rod 11, and an inner surface at an angle β from a position far from the light-emitting diode 12 on the side of the light guide plate 11. In this embodiment, the angle α of the first inclined surface 110 is 32 degrees, and the angle β of the second inclined surface 120 is 87 degrees.
As shown in FIG. 3 in which the groove 100 is enlarged, the first inclined surface 110 and the second inclined surface 120 are connected by a bottom surface 130, and the length of the bottom surface 130 is constant and 0.005 mm.
[0018]
FIG. 4 is a diagram for explaining the reason why the angle α of the first inclined surface 110 is set to 32 degrees. The horizontal axis indicates the angle α of the first inclined surface 110, and the vertical axis includes P waves and S waves. It shows the intensity of P-wave light emitted from the light guide plate side surface 11a of the light guide rod 11 with respect to the intensity of incident light. The solid line shows the value for the vertical component light that exits perpendicularly from the light guide plate side surface 11a of the light guide rod 11, and the broken line shows the value for the integrated value of all components. As can be understood from FIG. 4, when the angle α is 32 degrees, the number of P waves is the smallest and the number of S waves is the largest.
[0019]
FIG. 5 is a diagram showing a path of light of a vertical component that enters the first inclined surface 110 inclined at 32 degrees as described above and exits perpendicularly from the light guide plate side surface 11a, and is transmitted through the first inclined surface 110. The light is separated into light and reflected light, and the reflected light becomes light of a vertical component.
FIG. 5 is a diagram showing the ratio of reflection and transmission of the P wave and the S wave incident on the first inclined surface 110 inclined at 32 degrees with respect to the change in the incident angle, and is indicated by a thick solid line. Indicates the reflection ratio of the S wave, the thick broken line indicates the transmission ratio of the S wave, the thin solid line indicates the reflection ratio of the P wave, and the thin broken line indicates the transmission ratio of the P wave.
From this figure, it can be seen that when the incident angle is 34 °, about 14% of the S wave is reflected and about 86% is transmitted, and almost all of the P wave is transmitted without being reflected.
[0020]
FIG. 6 is a diagram showing the path of light that has entered the first inclined surface 110 inclined at 32 degrees as described above at an incident angle of 34 °. In this case, the reflected light exits vertically from the light guide plate side surface 11a. It becomes light of a vertical component.
[0021]
FIG. 7 shows the extinction ratio (P-wave / P-wave + S-wave) of the reflected light incident on the first inclined surface 110 inclined at 32 degrees as described above, that is, the thin solid line and the thick solid line in the graph of FIG. This is a graph showing the ratio. As can be seen from the figure, when the incident angle is 34 °, the extinction ratio is the smallest (zero), and only the S wave is emitted.
The above values are the refractive index n ₁ is of the case of 1.49, as described above.
[0022]
FIG. 8 is an exploded view for explaining a light path until the light emitted from the light source device 10 including the light guide rod 12 configured as described above reaches the liquid crystal display element 30. Actually, each member is in close contact.
Light emitted from the light emitting diode 12 is reflected inside the first inclined surface 110 of the light guide rod 11 as described above, travels toward the light guide plate side surface 11a, exits from the light guide plate side surface 11a, and enters the light guide plate 20. Light enters the light guide plate 20 from the surface 21. The light incident on the light guide plate 20 is vertically incident light only S-wave, and other obliquely incident light is light having many S-waves.
[0023]
The light that has entered the light guide plate 20 is reflected by the inner surface of the prism 23 on the surface of the light guide plate 20 and exits from the surface of the light guide plate 20 on the liquid crystal display element side. Light emitted from the surface of the light guide plate 20 on the liquid crystal display element side reaches the liquid crystal display element 30 after passing through the polarizer 40. The transmission axis W of the polarizer 40 is neither parallel nor perpendicular to the X-axis, and is inclined at about 45 degrees with respect to the X-axis. When the light exits the light guide plate 20, the light has a lot of S-waves, so that the light easily passes through the transmission axis W of the polarizer 40. Therefore, much light reaches the liquid crystal display element 30, and the brightness of the liquid crystal display element 30 is improved.
[0024]
Next, features of the second embodiment will be described. FIG. 9 is a view showing the structure of the light guide rod 13 according to the second embodiment, and the light guide rod 13 is formed of two kinds of materials, that is, shown in white in the figure. It is formed of a first material portion 13A made of a first material and a second material portion 13B made of a second material, which is shaded in the drawing. The first material portion 13A is formed of acrylic having a refractive index of 1.49 similar to that of the first embodiment, but the second material portion 13B is an adhesive having a lower refractive index.
[0025]
On the other hand, the light-emitting diode 12 is attached to the end of the light guide rod 13 in the X direction, but unlike the first embodiment, it is attached to only one end. The other end is provided with a reflector 15 via a quarter-wave plate 14. A reflection plate 18 is provided on the side 13a of the light guide rod 13 opposite to the light guide plate.
[0026]
The first material portion 13A has a light emitting diode side first inclined surface 210 and a light emitting diode side first inclined surface 220 that are parallel to each other, a light guide plate side surface, and a light guide plate side surface.
The second material portion 13B fills the space between two adjacent first material portions 13A, and the light guide plate side surface and the counter light guide plate side surface are flush with the light guide plate side surface and the counter light guide plate side surface of the first material portion 13A. Has been.
The angle between the light emitting diode side first inclined surface 210 and the anti-light emitting diode side first inclined surface 220 from the X direction is about 45 degrees. While the angle of the first inclined surface in the first embodiment is 32, what is such an angle, the refractive index n ₂ of the second material portion 13B of the first material portion 13A it is close to the refractive index n _1.
[0027]
The light incident on the light guide rod 13 from the light emitting diode 12 includes the P wave and the S wave, but is separated into reflected light and transmitted light on the light emitting diode side first surface 210 of the first member 13A, and the reflected light is There are many S waves. The transmitted light passes through the second member 13B and further enters the next first member 13A from the first inclined surface 220 on the side opposite to the light emitting diode. At this time, the refractive index n ₂ of the second member 13B <the first member 13B reflection does not occur because it is the refractive index n _1. When exiting the first member 13A, the above operation is performed in the same manner.
[0028]
The light that has reached the anti-light emitting diode side end surface 13c of the light guide rod 13 by repeating the above-described operation exits the anti-light emitting diode side end surface 13c, passes through the quarter wavelength plate 14, is reflected by the reflecting plate 15, and is again reflected. The light passes through the quarter-wave plate 14 and enters the light guide rod 13 from the end face 13c on the side opposite to the light emitting diode, and travels inside the first member 13A toward the end face on the light emitting diode side. This light is only an S wave due to the function of the １ ／ wavelength plate 14.
[0029]
The light traveling toward the light emitting diode side end face 13d is reflected by the anti-light emitting diode side first inclined surface 220 and goes out of the light guide rod 13 from the side of the light guide plate, but is reflected by the reflector 16 and again. Incident inside. The light that reenters the light guide rod 13 reaches the first inclined surface 220 on the side opposite to the light emitting diode, but is almost transmitted because the incident angle on this surface (the angle from the normal to the surface) is small. The light passes through the two members 13B and reaches the light-emitting diode-side first surface 210 of the adjacent first member 13A. However, here, the light is not reflected due to the above-described relationship of the refractive index, and is reflected from the side of the light guide plate of the adjacent first member 13A. The light exits toward the entrance surface 21 of the light guide plate 20. The light re-entering the light guide rod 13 from the side surface of the anti-light emitting diode is only the S-wave, and the light traveling toward the incident surface 21 of the light guide plate 20 as described above is also only the S-wave.
[0030]
In the second embodiment, light travels as described above, and almost only S-wave light enters the light guide plate 20. The light incident on the light guide plate 20 has properties as described in the first embodiment, and becomes light that easily exits the light guide plate 20 and passes through the transmission axis of the polarizer (see FIG. 7) 40. As a result, the brightness of the liquid crystal display element 30 (see FIG. 7) is improved.
[0031]
Next, features of the third embodiment will be described. FIG. 10 is a view showing the structure of a light guide rod 17 according to the third embodiment, and the light guide rod 17 is formed of two kinds of materials as in the second embodiment, that is, FIG. It is formed of a first material portion 17A shown in white and a second material portion 17B shown in hatching in the figure.
[0032]
However, the first material portion 17A and the second material portion 17B are not finely separated as in the second embodiment, and the continuous second material portion 17B causes the first material portion 17A to move in the Y direction. Is simply divided into two.
That is, the first center of the material portion 17A ₁ of the anti-light guide plate (light guide plate) is formed a second inclined surface 320 in succession to the first inclined surface 310, the first material portion 17A of the light guide plate the _second central side (counterclockwise light guide plate) are second inclined surface 420 are continuously formed in the first inclined surface 410.
[0033]
The first material portion 17A is made of acrylic having a refractive index of 1.49 similar to that of the first embodiment, while the second material portion 17B is an adhesive having a lower refractive index.
The angle of each inclined surface from the X direction is about 45 degrees. While the angle of the first inclined surface in the first embodiment is 32, a is the difference such an angle, the refractive index n ₂ of the second material portion 17B is refracted in the first material portion it is close to the ratio _{n 1.}
[0034]
The light incident on the light guide rod 17 from the light emitting diode 12 includes a P wave and an S wave. In the case of this embodiment, for example, as shown by a solid line, divided into reflected light and transmitted light at the second inclined surface 420 of the first material portion 17A _2, reflected light is often the S wave. Transmitted light, then passes through the second member 17B, is incident from the first material portion 17A ₂ in the first inclined surface 320 of the light guide plate, when the refractive index _{n 2} <first second member 17B reflection since a refractive index n ₁ of the member 17B does not occur. The effect of the above is performed in the same manner again through the first material portion 17A ₂ of the light guide plate.
[0035]
The light that has reached the end face of the light guide rod 17 on the side opposite to the light emitting diode by repeating the above-described operation exits the end face 17c of the light guide rod 17 on the side opposite to the light emitting diode, passes through the quarter-wave plate 14, is reflected by the reflecting plate 15, and is reflected again by one. / 4 is incident from the wavelength plate 14 as repulsive photodiode-side end face 17c into the light guide rod in a 17, it travels toward the light emitting diode side end surface 17d of the first material portion 17A ₁ of the anti-light guide plate. This light is only an S wave due to the function of the １ ／ wavelength plate 14.
[0036]
Light traveling toward the light-emitting diode side end surface 17d is divided into transmitted light and reflected light by the second inclined surface 320 of the first material portion 17A ₁ of Hanshirube light guide plate side. The reflected light exits the light guide rod 17 from the side surface of the light guide plate, but is reflected by the reflection plate 16 and enters the light guide rod 17 again. The light re-entering into the light guide rod within 17 reaches the second inclined surface 320 of the first material portion 17A ₂ of the light guide plate, the light is mostly a S-wave, the second member 17B and the light guide plate first it passes through the material portion 17A ₂ emitted toward the light guide plate side to the incident surface 21 of the light guide plate 20.
[0037]
Meanwhile, the light transmitted, if shown in this figure, divided into transmitted light and reflected light by the first inclined plane 310 of the first material portion 17A ₁ of the anti-light guide plate, the reflected light of the light guide plate transmitted through the first material portion 17A ₂ emitted toward the light guide plate side surface 17a on the incident surface 21 of the light guide plate 20, transmitted light, the second inclined surface of the next first material portion 17A ₁ of the anti-light guide plate At 320, the same is done.
[0038]
In the third embodiment, light travels as described above, and almost only S-wave light enters the light guide plate 20. The light incident on the light guide plate 20 has properties as described in the first embodiment, and becomes light that easily exits the light guide plate 20 and passes through the transmission axis of the polarizer (see FIG. 7) 40. As a result, the brightness of the liquid crystal display element 30 (see FIG. 7) is improved.
[0039]
【The invention's effect】
According to the invention described in each claim, the light emitted from the light source device is guided to the inside from the light incident side end face of the light guide plate disposed outside one surface of the liquid crystal display element, and the light is transmitted to the liquid crystal display element of the light guide plate. Is a liquid crystal lighting device for reflecting the light inside the first surface of the light guide plate and emitting the light from the second surface near the liquid crystal display device of the light guide plate to illuminate the liquid crystal display device.
When X, Y, and Z are three orthogonal directions,
The liquid crystal display element is formed by sandwiching a liquid crystal material between transparent plates and extends in the XY directions, and a light guide plate side is provided with a polarizer extending in the XY directions. The polarizer has a transmission axis inclined in the XY plane from the Y direction. Has,
The light guide plate has a light incident side end surface that extends elongated in the XZ direction, a first surface and a second surface that extend in the XY direction, a prism array formed on the first surface, and a peak and a valley of the prism array. The line extends in the X direction,
The light source device comprises: a light guide plate side face which is elongated in the X direction and is elongated in the Z direction and is opposed to the light incident side end face of the light guide plate; an anti-light guide plate side surface parallel to the light guide plate side surface; A light guide rod having two surfaces extending in the X direction and elongated in the Y direction so as to be long in the X direction and having a light emitting diode attached to at least one of the two end surfaces in the X direction;
The light guide rod has a plurality of first inclined surfaces extending from the light guide plate side toward the light guide plate side, and the first inclined surface is closer to the light emitting diode on the opposite light guide plate side and farther from the light emitting diode on the light guide plate side, The angle α of the first inclined surface from the X direction on the side of the light guide plate is selected to be an angle such that light emitted vertically from the side surface of the light guide plate toward the light source side end surface of the light guide plate is only S-wave light. .
In the liquid crystal lighting device configured as described above, the vertical light traveling toward the incident end face of the light guide plate is only S-wave light, and the non-vertical light has many S waves. When the light passes through the polarizer disposed in front of the liquid crystal display, a large amount of light coincides with the transmission axis of the polarizer, and the luminance of the liquid crystal display element is improved.
[Brief description of the drawings]
FIG. 1 is a top view of a first embodiment.
FIG. 2 is a diagram illustrating a change in the depth of a groove of the optical guide rod according to the first embodiment.
FIG. 3 is an enlarged view of a light guide rod according to the first embodiment.
FIG. 4 is a diagram illustrating a relationship between an angle of an inclined surface on a light emitting diode side of the light guide rod and an extinction ratio according to the first embodiment.
FIG. 5 is a diagram illustrating a reflection ratio and a transmission ratio of an S-wave and a reflection ratio and a transmission ratio of a P-wave with respect to a change in an incident angle in incident light.
FIG. 6 is a diagram showing a typical light path in a light guide rod according to the first embodiment.
FIG. 7 is a diagram illustrating a relationship between an incident angle of light hitting a light-emitting diode-side inclined surface of the light guide rod and an extinction ratio according to the first embodiment.
FIG. 8 is a diagram illustrating the progress of light in a liquid crystal display device including the liquid crystal lighting device according to the first embodiment.
FIG. 9 is a top view of the second embodiment.
FIG. 10 is a top view of the third embodiment.
[Explanation of symbols]
Reference Signs List 10 light source 11 light guide rod 12 light emitting diode 13 light guide rod 13A first material portion 13B second material portion 14 quarter-wave plate 15 reflector 16 reflector 17 light guide rod 17A ₁ ... (anti of light guide plate) the first material portion 17A ₂ ... (the light guide plate) the first material portion 17B ... second material portion 20 ... light guide plates 23 prisms 23a ... mountain 23b ... valley 30 ... liquid crystal display device 40 ... polarizer 100 ... groove 110 ... first inclined surface 120 ... second inclined surface 210 ... light emitting diode side first inclined surface 220 ... anti-light emitting diode side first inclined surface 310 ... (of the light guide plate side first material portion) ) First inclined surface 320 (of the first material portion on the light guide plate side) Second inclined surface 410 (of the first material portion on the light guide plate side) First inclined surface 420 (of the first material portion on the light guide plate side) 2nd slope

Claims (8)

Light emitted from the light source device is guided inside from the light incident side end face of the light guide plate disposed outside one surface of the liquid crystal display element, and reflected inside the first surface of the liquid crystal display element at the distal end. A liquid crystal lighting device for illuminating the liquid crystal display element by emitting light from the second surface of the light guide plate near the liquid crystal display element,
When X, Y, and Z are three orthogonal directions,
The liquid crystal display element is formed by sandwiching a liquid crystal material between transparent plates and extends in the XY directions, and a light guide plate side is provided with a polarizer extending in the XY directions. The polarizer has a transmission axis inclined in the XY plane from the Y direction. Has,
The light guide plate has a light incident side end surface that extends elongated in the XZ direction, a first surface and a second surface that extend in the XY direction, a prism array formed on the first surface, and a peak and a valley of the prism array. The line extends in the X direction,
The light source device comprises: a light guide plate side face which is elongated in the X direction and is elongated in the Z direction and is opposed to the light incident side end face of the light guide plate; an anti-light guide plate side surface parallel to the light guide plate side surface; A light guide rod having two surfaces extending in the X direction and elongated in the Y direction so as to be long in the X direction and having a light emitting diode attached to at least one of the two end surfaces in the X direction;
The light guide rod has a plurality of first inclined surfaces extending from the light guide plate side toward the light guide plate side, and the first inclined surface is closer to the light emitting diode on the opposite light guide plate side and farther from the light emitting diode on the light guide plate side, The angle α of the first inclined surface from the X direction on the side opposite to the light guide plate is selected such that light emitted vertically from the side surface of the light guide plate toward the light source side end surface of the light guide plate is only S-wave light. ,
The light guide rod is formed of a first material, the refractive index of the first material is n ₁ , the first material is in contact with the light guide rod with the first inclined surface as a boundary, and the first inclined surface extends from the first material toward the first inclined surface. When the refractive index of the second substance through which light passes through is defined as n ₂ ,
_{tan (90 -α) = n 2} / n 1 is selected so as to satisfy the liquid crystal lighting apparatus characterized by. A refractive index n ₁ of the first material forming the light guide rod 1.49, the second material is an air, a liquid crystal of claim 1 which α is 32 degrees, and wherein the Lighting equipment. The end of the first inclined surface on the light guide plate side in the Y direction is on the side of the light guide plate of the light guide rod, and the end on the light guide plate side in the Y direction is inside the light guide rod. The liquid crystal lighting device according to claim 1, wherein a second inclined surface reaching the side surface of the light guide plate is coupled. The liquid crystal lighting device according to claim 3, wherein the depth of the joint between the first inclined surface and the second inclined surface from the side surface of the light guide plate increases as the distance from the light emitting diode increases. . The light-emitting diode is attached to only one of the two ends in the X direction of the light guide rod, and the other end is provided with a reflector via a λ / 4 plate. A first diode-side inclined surface on the light-emitting diode side and a first diode-side inclined surface facing the first diode-side inclined surface, and a first inclined surface between the diode-side first inclined surface and the opposite diode-side first inclined surface. The liquid crystal lighting device according to claim 1, wherein two substances are interposed. The tip of the first inclined surface on the side of the light guide plate in the Y direction is on the side of the light guide plate of the light guide rod, and the end of the first inclined surface on the side of the light guide plate is on the side of the light guide plate of the light guide rod. 6. The liquid crystal lighting device according to 5. A second inclined surface is provided in addition to the first inclined surface, and the second inclined surface is a pair of a second diode-side inclined surface on the light emitting diode side and a second diode-side second opposed surface facing the diode-side second inclined surface. The liquid crystal lighting device according to claim 5, further comprising an inclined surface, wherein a second substance is interposed between the second inclined surface on the diode side and the second inclined surface on the opposite side to the diode. The diode-side first inclined surface and the opposite diode-side second inclined surface, and the diode-side first inclined surface and the diode-side second inclined surface are connected to each other inside the light guide rod. The liquid crystal lighting device according to claim 7.

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