JP2002157910A - Lighting system, electro-optical unit and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting system capable of restraining luminance irregularity with a small number of components, to provide an electro-optical unit using the lighting system and to provide an electronic apparatus using the electro- optical unit. SOLUTION: In this electro-optical unit 400, light emitted from point light sources 141 and 142 advances into a light guide plate 11 with light advancing in the inside of the light guide plate 11 without reflecting on a third reflecting surface 123 mixed with light advancing in the inside of the light guide plate 11 after reflecting on the third reflecting surface 123. In addition, the light having the highest luminance and passing the optical axis center of the point light sources 141 and 142 reflects on the third reflecting surface 123 and advances in the direction intercrossing with the light advancing in the inside of the light guide plate 11 without reflecting on the third reflecting surface 123, and thus the light emitted from each of the point light sources 141 and 142 advances in the inside of the light guide plate 11 in a similar form like that emitted from plural point light sources.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminating device using a point light source and a light guide plate, an electro-optical unit in which an electro-optical panel is illuminated by the illuminating device, and an electronic apparatus having the electro-optical unit. It is. More specifically, the present invention relates to a technique for uniformizing a luminance distribution in a light guide plate of a lighting device.

[0002]

2. Description of the Related Art In an electronic apparatus such as a portable telephone, a display section is often constituted by an electro-optical unit using a liquid crystal panel or the like. Among such electro-optical units, the one shown in FIG. 10A includes a liquid crystal panel 400 and a lighting device 10A that can illuminate the liquid crystal panel 400 from the back side. In the electro-optical unit 100A, the lighting device 10A
The light guide plate 11 includes a transparent light guide plate 11 having a rectangular planar shape, and a point light source unit 14A for irradiating light to the base end surface 116 among four end surfaces constituting the periphery of the light guide plate 11. The point light source unit 14A includes a light pipe 141A disposed so as to face the base end face 116 of the light guide plate 11, and a pair of Ls that allow light to enter the light pipe 141A from both end faces.
It comprises point light sources 142A and 143A made of ED. In addition, although the reflection surface is comprised on the back surface side of the light guide plate, and the circumference | surroundings, illustration is abbreviate | omitted about these reflection surfaces.

In the illuminating device 10A configured as described above, the light emitted from the point light sources 142A and 143A enters the light pipe 141A and then enters the light pipe 141A.
The light advances through the inside 41 </ b> A and is emitted to the base end face 116 of the light guide plate 11. The light incident on the light guide plate 11 in this manner is
The light travels through the light guide plate 11 and is emitted from the front surface side to illuminate the liquid crystal panel 400.

Here, the liquid crystal panel 400 can modulate the light incident from the back side while the light is transmitted to the front side. Therefore, an image can be displayed on the liquid crystal panel 400 by turning on or off each pixel included in the liquid crystal panel 400.
It can be seen from the front side.

[0005]

However, FIG.
The lighting device 10A shown in (A) requires the light guide plate 11 and the light pipe 141A, and has a problem that the cost is high because the number of components is large.

Therefore, the lighting device 10 shown in FIG.
B, point light sources 142B and 143B composed of a pair of LEDs are arranged on the base end face 116 of the light guide plate 11,
The light emitted from the point light sources 142B and 143B is directly
A configuration in which light is incident on the light guide plate 11 from the base end face 116 is conceivable. With such a configuration, the number of components can be reduced as compared with the configuration shown in FIG.

However, in the illuminating device 10B shown in FIG. 10B, the light emitted from the point light sources 142B and 143B travels through the light guide plate 11 with the same luminance distribution. There is a problem that uneven brightness occurs in the image. Such luminance unevenness can be suppressed by increasing the number of point light sources, but such a measure is not preferable because it increases the cost of the lighting device 10B.

[0008] In view of the above problems, an object of the present invention is to provide:
An object of the present invention is to provide an illumination device that can suppress luminance unevenness with a small number of components, an electro-optical unit using the illumination device, and an electronic device using the electro-optical unit.

[0009]

According to the present invention, a light guide plate and a point light source for emitting light into the light guide plate are provided. In a lighting device for emitting light from a front surface side of a light guide plate toward a panel-shaped illumination target, a first reflection surface is formed on a back surface side of the light guide plate, and a base end surface constituting a periphery of the light guide plate. A second reflecting surface is formed on the pair of side end surfaces of the pair of side end surfaces opposed to each other between the front end surface and the base end surface; The light source is disposed so that an emission optical axis is directed to a side end face facing the base end face near at least one of the pair of side end faces, and on the base end face side, a light flux emitted from the point light source is provided. Wherein at least the center of the optical axis and the base end face from the center of the optical axis; Wherein the third reflecting surface for reflecting a light directing light emitted by the side of the front end surface toward the is configured.

In the present invention, the light emitted from the point light source enters the light guide plate at a predetermined spread angle, and travels inside the light guide plate while being reflected by the first reflection surface and the second reflection surface. Are emitted from the surface side. Here, the light emitted from the point light source travels toward the opposing side end faces. In the present invention, at least the light of the light flux emitted from the point light source is located on the base end face side of the light guide plate. Since the third reflection surface is configured to reflect light emitted toward the base end face side from the axis center and the optical axis center toward the tip end face side, light emitted from the point light source is configured. Is the third
The light that travels inside the light guide plate without being reflected by the reflective surface and the light that travels inside the light guide plate after being reflected by the third reflective surface travel together in the light guide plate. For this reason, since the luminance distributions of these lights overlap, the bias of the luminance distribution of the light emitted from the light guide plate can be eliminated. Moreover, the light having the highest luminance passing through the center of the optical axis of the point light source is reflected by the third reflecting surface, and intersects with the light traveling in the light guide plate without being reflected by the third reflecting surface. The light travels in the light guide plate in the same manner as the light emitted from one point light source is emitted from a plurality of point light sources, such as traveling. Therefore,
Even with a configuration in which light emitted from a point light source is directly incident on the light guide plate without using a light pipe or the like, luminance unevenness does not occur in the light emitted from the light guide plate.

In the present invention, it is preferable that one point light source is disposed on each of a pair of opposed side end surfaces of the light guide plate. With this configuration, since the point light sources are arranged on both of the pair of side end surfaces, the luminance distribution emitted from each point light source is line-symmetric in the light guide plate, and both luminance unevennesses are canceled. Therefore, even in a lighting device that does not use a light pipe, it is possible to reliably prevent uneven luminance.

In the present invention, it is possible to adopt a configuration in which one of the point light sources is disposed on one of a pair of opposed side end surfaces of the light guide plate. When the point light source is reduced with the conventional configuration, the luminance unevenness becomes remarkable. In the present invention, the light having the highest luminance among the light emitted from the point light source is dispersed in the third reflection surface. Therefore, unevenness in brightness is not conspicuous in place of a lighting device using one point light source.

[0013] In the present invention, it is preferable that the third reflecting surface is formed as a convex curved surface projecting toward the point light source. 2 point light sources
When two are used, two third reflecting surfaces for two point light sources are formed in opposite directions, but if the third reflecting surface is formed of a curved surface protruding toward the point light source,
Since the two third reflecting surfaces can be formed as continuous curved surfaces, the boundary between the two third reflecting surfaces does not have a bent shape. Therefore, since the light emitted from the point light source is reflected in a state of being considerably dispersed on the third reflecting surface, it is possible to reliably prevent the occurrence of uneven brightness.

In the present invention, the third reflecting surface may be formed, for example, as a slope that is obliquely inclined with respect to the emission optical axis of the point light source. Further, the third reflecting surface may be configured as a concave curved surface that is concave in a light emitting direction of the point light source.

In the present invention, it is preferable that a prism-like convex or concave shape is formed on the diffuse reflection surface of the light guide plate.

In the present invention, a prism-shaped convex or concave shape may be formed on the diffuse reflection surface of the light guide plate and the opposite surface.

In the present invention, a prism-shaped convex or concave shape is formed on at least one of the diffuse reflection surface and the opposite surface of the light guide plate in a wavefront shape centering on the point light source. Is preferred.

The lighting apparatus applied to the present invention is used, for example, in an electro-optical unit having an electro-optical panel capable of displaying an image by light emitted from the surface side of the light guide plate. In such an electro-optical unit, since uniform light is incident on the electro-optical panel, a high-quality image without luminance unevenness can be displayed.

In such an electro-optical unit, the electro-optical panel is, for example, a liquid crystal panel that modulates light with a liquid crystal used as an electro-optical material.

Since such an electro-optical unit is designed to reduce the cost, it is effective to use the electro-optical unit to constitute a display unit in an electronic device which requires strict cost.

[0021]

Embodiments of the present invention will be described with reference to the accompanying drawings.

Embodiment 1 (Overall Configuration of Electronic Equipment) FIG. 1 is a perspective view showing the appearance of a portable telephone as an example of electronic equipment to which the present invention is applied, and FIGS. 2 (A) and 2 (B). FIG. 3 is a plan view of a lighting device used for an electro-optical unit used in the mobile phone, and a cross-sectional view of the electro-optical unit.

In FIG. 1, a display unit 2 using a liquid crystal panel 400 as an electro-optical panel is formed in an upper half of a mobile phone 1 (electronic device) of the present embodiment, and a lower half is formed in a lower half. Operation unit 3 on which a plurality of key buttons 301 are arranged
Is configured. A speaker hole 4 is formed above the display unit 2, and a microphone hole 5 is formed below the operation unit 3.

In forming the display unit 2 in the mobile phone 1, an electro-optical unit 100 having an illumination device 10 shown in FIGS. 2A and 2B is used. The electro-optical unit 100 includes a liquid crystal panel 400 (electro-optical panel / object to be illuminated) and a lighting device 10 capable of emitting light to the back side of the liquid crystal panel 400.

The illuminating device 10 has a light guide plate 11 made of a transparent plastic molded product and having a wedge-shaped cross section, and a liquid crystal panel 400 interposed between the light guide plate 11 and the front surface side of the light guide plate 11. Transparent surface cover 13
And two point light sources 141 and 142 formed of an LED or the like that emits light into the light guide plate 11. The front cover 13 is disposed such that the back surface side is interposed between the liquid crystal panel 400 and the air layer. Light guide plate 11
A diffuse reflection pattern 110 is formed on the back side of the substrate.

In the lighting device 10 of the present embodiment, the first reflection surface 121 is formed as a diffuse reflection surface on the back surface of the light guide plate 11 by a reflection sheet. Further, in the lighting device 10, a base end surface 116 constituting the periphery of the light guide plate 11, a front end surface 117 facing the base end surface 116, and a front end surface 117
And a pair of side end faces 11 opposed to each other between the end face 116 and the base end face 116.
8 and 119, a pair of side end faces 11
A second reflection surface 122 is formed by a reflection sheet for each of the reflection surfaces 8 and 119.

Here, the point light sources 141 and 142 are connected to the base end face 11 by a pair of side end faces 118 and 119 opposed to each other.
6 are located at positions where the second reflection surface 122 is not formed, facing the side end surfaces 118 and 119 facing each other. That is, of the point light sources 141 and 142, the point light source 141 disposed on the side of the side end surface 118 is
The outgoing optical axis is oriented to the side end face 119, and the side end face 11
The point light source 142 arranged on the side of the ninth side is arranged toward the side end face 118.

Further, in the lighting device 10 of the present embodiment, the point light sources 141 and 142 are provided on the base end face 116 side of the light guide plate 11.
The third reflection surface 1 that reflects at least the center of the optical axis and light emitted from the center of the optical axis toward the base end face 116 as light heading toward the distal end face 117 in the light flux emitted from
23 are configured. Here, the third reflecting surface 123
Is composed of two parts, a part facing the point light source 141 and a part facing the point light source 142, and any part is formed as a convex curved surface projecting toward the point light sources 141 and 142. .

In this embodiment, when forming the third reflecting surface 123, the base end surface 116 is concavely formed in an arc shape toward the front end surface 117, and the white resin molded product 120 is formed in the concave portion formed thereby. Is arranged. Therefore, the third reflection surface 123 is formed by the interface between the base end surface 116 of the light guide plate 11 and the resin molded product 120. Here, the planar shape of the light guide plate 11 is such that the base end face 116 is recessed,
Since the resin molded product 120 is fitted in the concave portion, the planar shape of the combination of the light guide plate 11 and the resin molded product 120 is rectangular.

In forming the third reflecting surface 123, a reflecting sheet may be used as in the case of the first reflecting surface 121 and the second reflecting surface 122, and the base end surface 116 may be used.
Alternatively, an aluminum film, a silver film, or the like may be formed.

(Structure of Liquid Crystal Panel 400) The structure of the liquid crystal panel 400 used as the electro-optical panel in the mobile phone 1 of the present embodiment will be described with reference to FIGS. 3, 4, and 5.

FIGS. 3 and 4 show the liquid crystal panel 4 respectively.
FIG. 9 is a perspective view and an exploded perspective view when 00 is viewed obliquely from below. FIG. 5 is a cross-sectional view of the liquid crystal panel 400.

In FIGS. 3, 4 and 5, a liquid crystal panel 400 is a passive matrix type color liquid crystal panel, and a pair of transparent glass members made of rectangular glass or the like bonded together by a sealing material 430 via a predetermined gap. A liquid crystal sealing region 435 is defined between the substrates by a sealant 430, and liquid crystal is sealed in the liquid crystal sealing region 435. Here, of the pair of transparent substrates, a substrate on which a plurality of rows of first electrode patterns 440 extending in the vertical direction in the liquid crystal sealing region 435 are formed is referred to as a first transparent substrate 410, and the liquid crystal sealing region The substrate on which a plurality of rows of second electrode patterns 450 extending in the horizontal direction within 435 are formed is referred to as a second transparent substrate 420.

As shown in FIG. 5, red (R) and green (G) regions are formed on the second transparent substrate 420 at regions corresponding to intersections between the first electrode pattern 440 and the second electrode pattern 450. , Blue (B) color filters 407R, 407
G, 407B are formed, and these color filters 40
7R, 407G, and 407B on the surface side, an insulating planarizing film 426, a second electrode pattern 450, and an alignment film 42.
2 are formed in this order. On the other hand, the first electrode pattern 440 and the alignment film 412 are formed on the first transparent substrate 410 in this order.

In the liquid crystal device 400, the second electrode pattern 450 is made of an ITO film (Indium Tin O 2).
xide / transparent conductive film). On the other hand, the first electrode pattern 440 is formed of a thin aluminum film, and a part of the light reaching the first electrode pattern 440 formed of the thin aluminum film is first.
, And a part of the light is reflected by the first electrode pattern 440. Therefore, the liquid crystal panel 400
The transflective liquid crystal panel has both a function as a transmissive liquid crystal panel and a function as a reflective liquid crystal panel. Note that a polarizing plate 461 is attached to an outer surface of the second transparent substrate 420, and a polarizing plate 462 is attached to an outer surface of the first transparent substrate 410.

In constructing such a semi-transmissive / semi-reflective liquid crystal panel 400, a first electrode pattern 440 is formed by an aluminum film or the like having a film thickness that completely reflects light, and a first electrode is formed. Of the patterns 440,
A small light transmitting hole may be formed at a portion that intersects with the second electrode pattern 450.

Referring to FIG. 3 and FIG.
0, both the input / output of signals to / from the outside and the continuity between the substrates are performed. Each of the substrate sides 41 located in the same direction of the first transparent substrate 410 and the second transparent substrate 420 is used.
A first terminal formation region 411 and a second terminal formation region 421 formed on the first transparent substrate 410 and the second transparent substrate 420 near 8, 428 are used. Here, as the second transparent substrate 420,
A substrate larger than the first transparent substrate 410 is used, and when the first transparent substrate 410 and the second transparent substrate 420 are bonded to each other, the second transparent substrate extends from the substrate side 418 of the first transparent substrate 410. The drive I
C490 is COG mounted. The second terminal formation region 421 of the second transparent substrate 420 is
Input / output terminals 481 are formed at a portion located closer to the substrate side 421 than 90, and the flexible substrate 70 is connected to these input / output terminals 481.

In the second terminal formation region 421, a portion located on the side of the liquid crystal sealing region 435 with respect to the driving IC 490 is used for conduction between the first transparent substrate 410 and the first transparent substrate 410. It is formed in a portion overlapping with the transparent substrate 410. In the first transparent substrate 410, the first terminal formation region 411 is
Since it is used for conduction between the substrate and the 0 side, it is formed at the overlapping portion with the second transparent substrate 420.

Accordingly, the first transparent substrate 410 and the second transparent substrate 420 are connected to each other by the sealing material 43 containing the inter-substrate conducting agent.
0, and the terminals for inter-substrate conduction are conducted between the substrates, and a signal is input from the input / output terminal 481 of the second transparent substrate 420 to the driving IC 490.
Is supplied to the first electrode pattern 440 and the second electrode pattern 450, so that each of the pixels corresponding to the intersection of the first electrode pattern 440 and the second electrode pattern 450 is driven. be able to.

(Operation and Effect of the Embodiment) The operation and effect of the embodiment will be described with reference to FIGS. Note that FIG.
(A) shows a state in which light emitted from the point light source travels in the light guide plate 11. For the purpose of clarifying the state, of the two point light sources 141 and 142, Only the path of the light emitted from the light source 141 is shown.

Referring to FIG. 2 and FIG.
0 is a semi-transmissive / semi-reflective type, so that light incident from the back side can be modulated in the process of transmitting to the front side, and can be transmitted through the front cover 13 to the front side. It is also possible to modulate this light in the process of reflecting external light incident from the surface and exiting from the surface side.

Accordingly, in the electro-optical unit 100, the light emitted from the point light sources 141 and 142 of the lighting device 10 enters the light guide plate 11 and then enters the light guide plate 1.
The light travels through the light guide plate 11 while being repeatedly reflected within the light guide 1, and is emitted toward the liquid crystal panel 400 from the surface side. Therefore, in the liquid crystal panel 400, if the alignment state of the liquid crystal 404 for each pixel is controlled by the electric field applied to the first electrode pattern 440 and the second electrode pattern 450, the light is incident from the back side of the liquid crystal panel 400. The first light
After passing through the electrode pattern 440, the liquid crystal 4
04, and then the liquid crystal panel 400
Are emitted from the surface side. Therefore, an image is displayed on the liquid crystal panel 400, and this image can be viewed through the front cover 13 (transmission mode).

Further, in the electro-optical unit 400 of the present embodiment, external light transmitted through the front cover 13 and incident on the front surface side of the liquid crystal panel 400 is reflected by the first electrode pattern 440, and then reflected on the surface of the liquid crystal panel 400. Emitted from the side. Since such light is also modulated by the liquid crystal 404 for each pixel, an image is displayed on the liquid crystal panel 400, and the image can be viewed through the front cover 13 (reflection mode).

In the lighting device 10 of the present embodiment, FIG.
As shown in (A), the point light sources 141 and 142 are arranged with their emission optical axes facing the side end faces 118 and 119 facing each other. A third reflection surface 123 is formed to reflect light emitted toward the base end face 116 side from the center and the center of the optical axis toward the front end face 117 side. Accordingly, light emitted from the point light sources 141 and 142 enters the light guide plate 11 at a predetermined spread angle, and is reflected inside the light guide plate 11 while being reflected by the first reflection surface 121 and the second reflection surface 122. At this time, the point light sources 141, 1
The light emitted from the light guide plate 42 travels inside the light guide plate 11 without being reflected by the third reflection surface 123 and the third reflection surface 123
Then, the light traveling in the light guide plate 11 travels in the light guide plate 11 in a mixed state with the light traveling in the light guide plate 11 after being reflected. For this reason,
Since the two luminance distributions overlap, it is possible to eliminate the bias of the luminance distribution.

Further, the light having the highest luminance passing through the center of the optical axis of the point light sources 141 and 142 is reflected by the third reflecting surface 11, and is not reflected by the third reflecting surface 123 but passes through the light guide plate 11. A point light source 14 such as traveling in a direction intersecting with the traveling light
The light emitted from each of the light sources 1 and 142 travels in the light guide plate 11 in the same manner as the light emitted from the plurality of point light sources.
Therefore, without using a light pipe or the like, the point light source 141,
Even if the light emitted from the light guide 142 is directly incident on the light guide plate 11, the light emitted from the surface side of the light guide plate 11 does not have uneven brightness. Therefore, the liquid crystal panel 40
At 0, the quality of the image displayed in the transmission mode is high.

Further, since one point light source 141, 142 is disposed on each of the pair of opposite side end surfaces 118, 119 of the light guide plate 11, one point light source 141, 142 is provided.
The brightness distribution of the light emitted from the light guide plate 11
It is axisymmetric inside. Therefore, both the brightness unevennesses are canceled out, so that even in the lighting device 10 not using the light pipe, the occurrence of the brightness unevenness can be surely prevented.

Further, since the third reflecting surface 123 is formed as a convex curved surface protruding toward each of the point light sources 141 and 142, the third reflecting surface 123 is provided on each of the point light sources 141 and 142 as in this embodiment. Even when the third reflecting surface 123 is formed, a portion corresponding to the third reflecting surface 123 for the point light source 141 and the third reflecting surface 1 for the point light source 142
The portion corresponding to 23 is formed as a continuous and continuous curved surface. For this reason, since the third reflection surface 123 does not have a bent shape, the light reflected by the third reflection surface 123 is dispersed in a light-dispersing state in the light guide plate 1 without bias.
It is reflected within 1. Therefore, according to the present embodiment, it is possible to reliably prevent the occurrence of uneven brightness.

[Second Embodiment] FIG. 6 is a plan view of a lighting device according to a second embodiment of the present invention. FIG. 6 also shows a state in which light emitted from the point light source travels in the light guide plate 11, but for the purpose of clarifying the state, of the two point light sources 141 and 142, 141
The path of only the light emitted from is shown. Note that this embodiment, and Embodiments 3 and 4 described later,
The basic configuration of any one of the fifth embodiments is the same as that of the first embodiment, and differs only in the configuration of the third reflecting surface 123 and the number of point light sources. Therefore, only the characteristic portions of each embodiment will be described, and description of the other configurations will be omitted.

In FIG. 6, also in this embodiment, the lighting device 10 of the electro-optical unit 100 includes a light guide plate 11 made of a transparent plastic molded product and having a wedge-shaped cross section, and an LED for emitting light into the light guide plate 11. And two point light sources 141 and 142 composed of the same.

Also in this embodiment, the point light sources 141 and 142 are provided at the positions where the second reflecting surface 122 is not formed near the base end surface 116 on the pair of opposed side end surfaces 118 and 119. It is arranged toward 118 and 119, respectively.

Further, on the side of the base end face 116 of the light guide plate 11, of the light beams emitted from the point light sources 141 and 142, at least the center of the optical axis and the light emitted from the center of the optical axis toward the base end face 116. Is configured as a third reflection surface 123 that reflects the light toward the front end face 117 side. In the present embodiment, when forming the third reflection surface 123, the base end surface 116 is recessed in a triangular shape toward the front end surface 117, and the white resin molded product 120 is arranged in the recess formed thereby. It is. Therefore, the base end surface 1 of the light guide plate 11
A portion corresponding to the oblique side of the triangle at the interface between the resin molding 120 and the resin member 120 forms the third reflection surface 123.

In the illuminating device 10 thus configured, the light emitted from the point light sources 141 and 142 is not reflected by the third reflecting surface 123 but travels in the light guide plate 11 and the third light.
The light that travels in the light guide plate 11 after being reflected by the reflection surface 123 travels in the light guide plate 11 in a mixed state. For this reason, since both luminance distributions overlap, the deviation of the luminance distribution can be eliminated.

Moreover, the light having the highest luminance passing through the center of the optical axis of the point light sources 141 and 142 is reflected by the third reflecting surface 11 and passes through the light guide plate 11 without being reflected by the third reflecting surface 123. A point light source 14 such as traveling in a direction intersecting with the traveling light
The light emitted from each of the light sources 1 and 142 travels in the light guide plate 11 in the same manner as the light emitted from the plurality of point light sources.
Therefore, even if the light emitted from the point light sources 141 and 142 is directly incident on the inside of the light guide plate 11, the brightness emitted from the surface side of the light guide plate 11 does not have uneven brightness. Therefore, the quality of the image displayed in the transmission mode on the liquid crystal panel 400 is high.

The brightness distribution of the light emitted from each of the point light sources 141 and 142 is line-symmetric within the light guide plate 11. Therefore, since both brightness unevennesses are canceled out, even in the lighting device 10 not using the light pipe,
It is possible to reliably prevent the occurrence of uneven brightness.

[Embodiment 3] FIG. 7 is a plan view of a lighting apparatus according to Embodiment 3 of the present invention. FIG. 7 also shows a state in which light emitted from the point light source travels in the light guide plate 11. For the purpose of clarifying the state, the point light source of the two point light sources 141 and 142 is used. 141
The path of only the light emitted from is shown.

In FIG. 7, also in this embodiment, the electro-optical unit 100 includes a liquid crystal panel 400 (electro-optical panel / object to be illuminated) and an illuminating device 10 capable of emitting light to the back side of the liquid crystal panel 400. The lighting device 10 includes a light guide plate 11 made of a transparent plastic molded product and having a wedge-shaped cross section, and an LED for emitting light into the light guide plate 11.
And two point light sources 141 and 142 composed of the same.

Also in the present embodiment, the point light sources 141 and 142 are positioned at positions where the second reflecting surface 122 is not formed near the base end surface 116 on the pair of opposed side end surfaces 118 and 119. It is arranged toward 118 and 119, respectively.

Further, in the lighting device 10 of the present embodiment, the point light sources 141 and 142 are provided on the base end face 116 side of the light guide plate 11.
The third reflection surface 1 that reflects at least the center of the optical axis and light emitted from the center of the optical axis toward the base end face 116 as light heading toward the distal end face 117 in the light flux emitted from
23 are configured. In this embodiment, the third reflecting surface 12
3 is formed, the base end face 116 is connected to the front end face 117.
The white resin molded product 120 is arranged in the recess formed by the recess. Here, the third
Is composed of two parts, a part facing the point light source 141 and a part facing the point light source 142. In any case, the concave surface is concave in the emission direction of the point light sources 141 and 142. It is formed as.

In the illumination device 10 thus configured, the light emitted from the point light sources 141 and 142 is not reflected by the third reflection surface 123 but travels in the light guide plate 11 and the third light.
The light that travels in the light guide plate 11 after being reflected by the reflection surface 123 travels in the light guide plate 11 in a mixed state. For this reason, since both luminance distributions overlap, the deviation of the luminance distribution can be eliminated.

Moreover, the light of the highest luminance passing through the center of the optical axis of the point light sources 141 and 142 is reflected by the third reflecting surface 11 and is not reflected by the third reflecting surface 123 but passes through the light guide plate 11. A point light source 14 such as traveling in a direction intersecting with the traveling light
The light emitted from each of the light sources 1 and 142 travels in the light guide plate 11 in the same manner as the light emitted from the plurality of point light sources.
Therefore, even if the light emitted from the point light sources 141 and 142 is directly incident on the inside of the light guide plate 11, the brightness emitted from the surface side of the light guide plate 11 does not have uneven brightness. Therefore, the quality of the image displayed in the transmission mode on the liquid crystal panel 400 is high.

The brightness distribution of the light emitted from each of the point light sources 141 and 142 is line-symmetric in the light guide plate 11. Therefore, since both brightness unevennesses are canceled out, even in the lighting device 10 not using the light pipe,
It is possible to reliably prevent the occurrence of uneven brightness.

Fourth Embodiment FIG. 8 is a plan view of a lighting device according to a fourth embodiment of the present invention.

Referring to FIG. 8, also in this embodiment, the electro-optical unit 100 includes a liquid crystal panel 400 (electro-optical panel / object to be illuminated) and a lighting device 10 capable of emitting light to the back side of the liquid crystal panel 400. ing.

In the lighting device 10, a light guide plate 11 made of a transparent plastic molded product and having a wedge-shaped cross section, and a point light source 141 made of an LED or the like for emitting light into the light guide plate 11
However, in this embodiment, the first, second, and third embodiments are used.
Unlike the third embodiment, only one point light source 141 is used.

In this embodiment, the point light source 141 is arranged on the side end face 118 side toward the opposing side end face 119.

Further, in the illumination device 10 of this embodiment, at least the center of the optical axis of the light flux emitted from the point light source 141 on the base end face 116 side of the light guide plate 11 and the base end face 116 side of the optical axis center. The light emitted toward the front face 117
Is formed as a third reflecting surface 123 that reflects light traveling toward the side. In the present embodiment, when forming the third reflection surface 123, the base end surface 116 is recessed toward the front end surface 117, and the white resin molded product 120 is arranged in the recess formed thereby. Here, the third reflecting surface 123 is formed as a concave curved surface that is concave in the emission direction of the point light source 141.

In the lighting device 10 configured as described above, the light emitted from the point light source 141 is reflected by the third reflecting surface 1.
The light traveling in the light guide plate 11 without being reflected at 23 and the light traveling in the light guide plate 11 after being reflected by the third reflection surface 123 are mixed in the light guide plate 11. Become. For this reason, since both luminance distributions overlap, the deviation of the luminance distribution can be eliminated.

Further, the light having the highest luminance passing through the center of the optical axis of the point light source 141 is reflected by the third reflecting surface 11 and is reflected by the third reflecting surface 11.
The light emitted from the point light source 141 is guided in a form similar to that emitted from a plurality of point light sources, such as traveling in a direction intersecting with the light traveling in the light guide plate 11 without being reflected by the reflection surface 123. It travels inside the light plate 11. Therefore, even if the light emitted from the point light source 141 is directly incident on the inside of the light guide plate 11, the uneven brightness of the light emitted from the surface side of the light guide plate 11 is not conspicuous. Therefore, the quality of the image displayed in the transmission mode on the liquid crystal panel 400 is high.

[Other Embodiments] FIG.
(B), (C), and (D) show light guide plates in which light is reflected on a front surface (light emission surface) and a back surface (diffuse reflection surface) in a light guide plate used in a lighting device to which the present invention is applied. Explanatory diagram showing how the light travels through the inside, explanatory diagram showing an example of the uneven shape formed on this light guide plate, explanatory diagram showing another uneven shape formed on this light guide plate, and formed on this light guide plate It is explanatory drawing which shows another uneven | corrugated shape performed.

In the lighting device to which the present invention is applied, taking the light guide plate of the fourth embodiment as an example, as shown in FIG. The light travels from the base end face 116 side to the tip end face 117 in the light guide plate 11 while being reflected on the light emission surface) and the back surface (diffuse reflection surface) on which the diffuse reflection pattern 110 is formed. As shown in FIG. 9B, prism-shaped irregularities 111 are formed on the back surface as a diffuse reflection surface.
May be formed. Further, as shown in FIG. 9C, the prismatic irregularities 1 are formed on both the front and back surfaces of the light guide plate 11.
11 may be formed. Further, as shown in FIG. 9D, unevenness 111 may be formed on at least one of the front surface and the back surface of the light guide plate 11 in a wavefront shape centered on the point light source 141.

In the above embodiment, an example in which the present invention is applied to the lighting device 10 used for the electro-optical unit 100 of the mobile phone 1 has been described. However, the present invention may be applied to other lighting devices. Good.

[0072]

As described above, according to the present invention, the light emitted from the point light source travels in the light guide plate without being reflected by the third reflecting surface, and the light emitted by the third reflecting surface. The light that travels inside the light guide plate after being reflected travels inside the light guide plate in a mixed state. For this reason, since the luminance distributions of these lights overlap, the bias of the luminance distribution of the light emitted from the light guide plate can be eliminated. Moreover, the light having the highest luminance passing through the center of the optical axis of the point light source is reflected by the third reflecting surface, and intersects with the light traveling in the light guide plate without being reflected by the third reflecting surface. The light travels in the light guide plate in the same manner as the light emitted from one point light source is emitted from a plurality of point light sources, such as traveling. Therefore, even if the light emitted from the point light source is directly incident on the light guide plate without using a light pipe or the like, the brightness emitted from the light guide plate does not have uneven brightness.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the appearance of a mobile phone as an example of an electronic apparatus to which the present invention is applied.

FIGS. 2A and 2B are a plan view of a lighting device used for the electro-optical unit according to Embodiment 1 of the present invention and a cross-sectional view of the electro-optical unit, respectively.

FIG. 3 is a perspective view of a liquid crystal panel used in the mobile phone shown in FIG. 1 as viewed obliquely from below.

FIG. 4 is an exploded perspective view of the liquid crystal panel used in the mobile phone shown in FIG. 1 as viewed obliquely from below.

FIG. 5 is a sectional view of the liquid crystal panel shown in FIGS. 3 and 4.

FIG. 6 is a plan view of a lighting device used for the electro-optical unit according to Embodiment 2 of the present invention.

FIG. 7 is a plan view of a lighting device used for an electro-optical unit according to Embodiment 3 of the present invention.

FIG. 8 is a plan view of a lighting device used for an electro-optical unit according to Embodiment 4 of the present invention.

FIG. 9 (A), (B), (C), (D)
FIG. 3 is an explanatory view showing a state in which light travels in the light guide plate while being reflected on the front surface (light emission surface) and the back surface (diffuse reflection surface) in the light guide plate used in the lighting device to which the present invention is applied.
Explanatory diagram showing an example of the uneven shape formed on this light guide plate,
FIG. 9 is an explanatory diagram showing another uneven shape formed on the light guide plate, and an explanatory diagram showing still another uneven shape formed on the light guide plate.

FIGS. 10A and 10B are explanatory diagrams of a lighting device used for a conventional electro-optical unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mobile telephone (electronic device) 2 Display part 3 Operation part 4 Speaker hole 5 Microphone hole 10 Lighting device 11 Light guide plate 13 Surface cover 100 Electro-optical unit 110 Diffuse reflection pattern 116 Base end surface of light guide plate 117 Front end surface of light guide plate 118, 119 side end surface of light guide plate 121 first reflection surface 122 second reflection surface 123 third reflection surface 141, 142 point light source 301 key button 400 liquid crystal panel (electro-optical panel)

Claims (12)

[Claims] 1. A light guide plate, and a point light source for emitting light into the light guide plate, and light emitted from the point light source is emitted from a surface side of the light guide plate toward a panel-shaped illumination target. In the lighting device, a first reflecting surface is formed on a back surface side of the light guide plate, and a base end surface surrounding the light guide plate, a front end surface facing the base end surface, the front end surface, and Of a pair of side end surfaces opposed to each other with a base end surface, a second reflection surface is formed on the pair of side end surfaces, and the point light source is the base end surface on at least one of the pair of side end surfaces. It is arranged toward a side end face that is close to and opposed to the base end face side, out of the luminous flux from the point light source,
A lighting device comprising: at least a center of an optical axis and a third reflecting surface configured to reflect light emitted from the center of the optical axis toward the base end surface as light directed toward the distal end surface. . 2. The lighting device according to claim 1, wherein one of the point light sources is disposed on one of a pair of opposed side end surfaces of the light guide plate. 3. The lighting device according to claim 1, wherein one point light source is arranged on each of a pair of opposed side end surfaces of the light guide plate. 4. The method according to claim 1, wherein
The lighting device according to claim 1, wherein the third reflecting surface is configured as a convex curved surface protruding toward the point light source. 5. The method according to claim 1, wherein
The lighting device according to claim 1, wherein the third reflection surface is configured as a slope that is obliquely inclined with respect to an emission optical axis of the point light source. 6. The method according to claim 1, wherein
The illumination device according to claim 1, wherein the third reflection surface is configured as a concave curved surface that is concave in a light emission direction of the point light source. 7. The method according to claim 1, wherein
A lighting device, wherein a prism-like convex or concave shape is formed on the diffuse reflection surface of the light guide plate. 8. The method according to claim 1, wherein
An illumination device, wherein a prism-like convex shape or a concave shape is formed on a diffuse reflection surface of the light guide plate and a facing surface thereof. 9. The method according to claim 1, wherein
A lighting device, wherein a prism-shaped convex or concave shape is formed on at least one of a diffusion surface and a facing surface of the light guide plate in a wavefront shape centered on the point light source. 10. An electro-optical unit using the illuminating device defined in any one of claims 1 to 9, further comprising an electro-optical panel capable of displaying an image by light emitted from a surface side of the light guide plate. An electro-optical unit, comprising: 11. The electro-optical unit according to claim 10, wherein the electro-optical panel is a liquid crystal panel that modulates light with a liquid crystal used as an electro-optical material. 12. An electronic apparatus, comprising: a display unit including the electro-optical unit defined in claim 10;