JP2002100232A - Surface light source device and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the abnormal light emission of a light guide plate by preventing damage to the light guide plate caused by fine rigid dust. SOLUTION: A light guide plate support parts 13 for supporting the side edges of backside 4a of a light guide plate 4 via a reflecting sheet 3 are formed in the bottom wall (frame panel) 6 of the recess 12 of a frame 2, which successively houses the reflecting sheet 3, the plate 4 and a liquid crystal display panel 5. A counter sinking part 14 is formed on the inside section of the supporting part 13. The sinking part 14, recessed with respect to the support part 13, houses the fine rigid dust intruding into the space between the reflecting sheet 3 and the bottom wall 6. Consequently, the dust is not rubbed against the reflecting sheet 3 and the plate 4 by the bottom wall 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device such as a portable telephone or an electronic organizer, and a surface light source device used for the image display device.

[0002]

2. Description of the Related Art For example, in a liquid crystal display device used as an image display device of a portable telephone, a surface light source device is disposed on the back side of a liquid crystal display panel (member to be illuminated), and light emitted from the surface light source device is provided. Thereby, the liquid crystal display panel is illuminated in a planar manner.

FIG. 12 shows such a conventional liquid crystal display device 31. In the liquid crystal display device 31, a reflection sheet 34 is disposed on the back surface 33 side of a light guide plate 32, and the light guide plate 32 and the reflection sheet 34 are supported by a bottom wall (frame panel) 36 of a frame 35. . Then, LE 37 serving as a light source is provided on the side surface 37 of the light guide plate 32.
D (light emitting diode) 38 is arranged. On the other hand, a liquid crystal display panel 41 as a member to be illuminated is disposed on the emission surface 40 side of the light guide plate 32 so as to face the light guide plate 32.

A liquid crystal display device 31 having such a structure is
Light emitted from the ED 38 enters the inside of the light guide plate 32 from the side surface 37 of the light guide plate 32, and the incident light propagates inside the light guide plate 32, and of the light propagating inside the light guide plate 32, On the other hand, light incident at an angle equal to or smaller than the critical angle is emitted from the emission surface 40 to the outside of the light guide plate 32, and the emitted light illuminates the liquid crystal display panel 41 in a planar manner.

Here, a printed circuit board 42 for driving and controlling the liquid crystal display panel 41 is fixed to the back surface 43 of the bottom wall 36, and the heat generated by the printed circuit board 42 is blocked by the bottom wall 36. In addition, the light guide plate 32 and the liquid crystal display panel 41 are hardly affected by the heat of the printed circuit board 42.

The conventional liquid crystal display device 31 as described above
Is used to secure the rigidity of the frame 35 in addition to the above-described reason of blocking the heat of the printed circuit board 42,
In order to form an electromagnetic wave shielding layer on the back surface 43 of the bottom wall 36, the bottom wall 36 is not lightened.

[0007]

However, in such a conventional liquid crystal display device 31, the bottom wall 36 comes into contact with the entire surface of the reflection sheet 34, and the reflection sheet 3
Since there is almost no gap between the bottom wall 4 and the bottom wall 36, when hard fine dust enters between the bottom wall 36 and the reflection sheet 34 or between the reflection sheet 34 and the light guide plate 32, the liquid crystal display 31 The reflection sheet 34 and the light guide plate 32 may be damaged by hard dust due to the influence of vibration or the like at the time of conveyance, and abnormal light emission due to the scratch may occur. If hard fine dust exists between the reflection sheet 34 and the bottom wall 36, the light guide plate 32 may be damaged by the hard fine dust via the reflection sheet 34, and the light guide plate 32 may emit abnormal light. Was.

Accordingly, an object of the present invention is to improve the structure of a surface light source device constituting a liquid crystal display device and to solve the above-mentioned problems of the prior art.

[0009]

According to the first aspect of the present invention, a frame panel for supporting the light guide plate is disposed on the back side of the light guide plate, and light from a light source is emitted in a planar manner through the light guide plate. The present invention relates to a surface light source device. Further, the frame panel is characterized in that a light guide plate supporting portion for supporting a rear edge of the light guide plate is formed so as to protrude more toward the light guide plate than other portions.

A second aspect of the present invention relates to a surface light source device in which a frame panel for supporting the light guide plate is disposed on the back side of the light guide plate, and light of a light source is emitted in a plane through the light guide plate. is there. The frame panel is formed with a plurality of protrusions for supporting the rear surface side of the light guide plate, and at least the front ends of the protrusions are formed in a substantially semicircular cross section.

A third aspect of the present invention relates to a surface light source device in which a frame panel for supporting the light guide plate is disposed on the back side of the light guide plate, and light of a light source is emitted in a plane through the light guide plate. is there. The frame panel is formed with a light guide plate supporting portion for supporting the rear edge of the light guide plate, and a projection for supporting the rear surface of the light guide plate between the light guide plate support portions. And at least the tip of the projection is formed in a substantially semicircular cross section.

According to a fourth aspect of the present invention, there is provided a surface light source device in which a frame panel supporting the light guide plate is disposed on a back surface side of the light guide plate, and light of a light source is emitted in a plane through the light guide plate. is there. A gap is formed between the frame panel and the light guide plate by disposing a spacer that supports at least a rear edge of the light guide plate.

According to a fifth aspect of the present invention, in the surface light source device according to any one of the first to fourth aspects, the space formed between the frame and the light guide plate is easily deformed. It is characterized in that a filler is interposed.

According to a sixth aspect of the present invention, there is provided an image display device comprising: the surface light source device according to any one of the first to fifth aspects;
And a member to be illuminated disposed on the emission surface side of the light guide plate of the surface light source device.

Embodiments of the present invention will be described below in detail with reference to the drawings.

[First Embodiment] FIGS. 1 to 3 show an image display apparatus 1 according to a first embodiment of the present invention. FIG. 1 is an exploded perspective view of the image display device 1 according to the present embodiment. FIG. 2 is a plan view of the image display device 1, and FIG. 3 is a longitudinal sectional view of the image display device 1 taken along line AA in FIG.

As shown in these figures, the image display device 1
In the frame 2, a reflection sheet 3, a light guide plate 4, and a liquid crystal display panel 5 as an illuminated member are sequentially accommodated in a frame 2, and a rear surface 6a of a bottom wall (frame panel) 6 of the frame 2 is used for driving and controlling the liquid crystal display panel. A plurality of LEDs (light emitting diodes) 10 as light sources are arranged so as to face the incident surface (side surface) 8 of the light guide plate 4. In these figures, the frame 2, the reflection sheet 3, the light guide plate 4, and the LED 10 constitute a surface light source device 11 for illuminating the liquid crystal display panel 5 in a planar manner.

The frame 2 is, as shown in FIGS.
It is made of PC (polycarbonate), ABS (acrylonitrile-butadiene-styrene resin), or the like, and has a recess 12 for accommodating the reflection sheet 3, the light guide plate 4, and the liquid crystal display panel 5. Recess 12 of this frame 2
In order to accommodate the light guide plate 4 having a substantially wedge-shaped cross section, the bottom wall 6 is formed so as to be inclined according to the shape of the light guide plate 4. Further, a light guide plate support portion 13 that supports an edge on the back surface 4a side of the light guide plate 4 is formed on the bottom wall 6 of the recess 12 of the frame 2.

A counterbore portion 14 recessed from the light guide plate support portion 13 is formed inside the light guide plate support portion 13, and a space is formed on the lower surface side of the reflection sheet 3 by the counterbore portion 14. I have. The counterbore portion 14 is formed to have a size substantially corresponding to a portion (effective light emitting area) used for illumination in the light exit surface 4b of the light guide plate 4. or,
In the frame 2, a plurality of light source receiving portions 15 opening to the recesses 12 are formed in order to arrange a plurality of LEDs 10 so as to face the incident surface 8 of the light guide plate 4.

Light guide plate support 13 in recess 12 of frame 2
On the upper side, a reflection sheet 3 made of a resin such as PET (polyethylene terephthalate) having excellent light reflectivity is arranged.
The reflection sheet 3 has a rectangular planar shape so as to face the back surface 4 a of the light guide plate 4, and functions to reflect light emitted from the back surface 4 a of the light guide plate 4 and return the light to the inside of the light guide plate 4. When the light reflectivity of the bottom wall 6 of the recess 12 of the frame 2 can be sufficiently expected, the reflection sheet 3 can be omitted.

The light guide plate 4 is made of PC (polycarbonate),
It is formed of PMMA (polymethyl methacrylate), a cycloolefin resin, or the like, and has a substantially rectangular planar shape. Further, the light guide plate 4 is formed such that the thickness on one side surface (incident surface 8) side is larger than that on the other side surface 16 side, and as shown in FIG. The surface is formed so as to have a substantially wedge shape.

The image display device 1 having such a configuration is provided with an LE
Light emitted from D10 enters the inside of the light guide plate 4 from the incident surface 8 of the light guide plate 4, and the incident light propagates inside the light guide plate 4. The light propagating inside the light guide plate 4 is emitted from the light exit surface 4b to the outside of the light guide plate 4 and illuminates the liquid crystal display panel 5 when the incident angle with respect to the light exit surface 4b becomes smaller than the critical angle in the process of propagation. . In addition, since light with substantially uniform brightness is emitted in a planar manner from the emission surface 4b of the light guide plate 4, the liquid crystal display panel 5 is surface-illuminated with substantially uniform brightness.

As described above, in the present embodiment, the light guide plate 4
A counterbore portion 14 having a size substantially corresponding to the effective light-emitting area is formed on the bottom wall 6 of the concave portion 12 of the frame 2, and the reflection sheet 3 and the light guide plate 4 are supported by the light guide plate support portion 13 of the frame 2. Since the supported portion is the edge on the back surface 4a side that is not directly used for illumination, the light guide plate 4 and the reflection sheet 3 are temporarily used.
Even if hard fine dust adheres between the light guide plate 3 and the light guide plate support 13, a portion substantially corresponding to the effective light emitting area of the light guide plate 4 is hardly damaged by the hard fine dust.
That is, even if hard fine dust adheres to the back surface 4a of the light guide plate 4 and between the portion corresponding to the effective light emitting area and the reflective sheet 3, the counterbore portion 14 is formed on the frame 2 side. In addition, hard fine dust is not rubbed against the back surface 4a of the light guide plate 4 by the bottom wall 6 of the frame 2, and the portion of the light guide plate 4 facing the effective light emitting area is not easily damaged. Hard fine dust entering between the reflection sheet 3 and the frame 2 is accommodated in the counterbore portion 14 and does not come into contact with the reflection sheet 3. The light guide plate 4 is not damaged. Therefore, the surface light source device 11 according to the present embodiment and the image display device 1 including the surface light source device
And the occurrence of abnormal light emission due to scratches on the light guide plate 4 can be suppressed, and high-quality image display can be achieved.

In this embodiment, since the light guide plate support 13 is in close contact with the back surface side edge of the reflection sheet 3, the back surface of the reflection sheet 3 and the space between the reflection sheet 3 and the light guide plate 4 are provided. Fine dust does not enter, and together with the effect of the counterbore portion 14 containing fine dust, the reflection sheet 3 and the light guide plate 4 can be effectively prevented from being damaged by hard fine dust.

In the present embodiment, as described above, the printed circuit board 7 for driving and controlling the liquid crystal display panel 5 is attached to the back surface 6a of the bottom wall 6 of the frame 2, and the heat generated by the printed circuit board 7 Is blocked by the frame 2 and is not easily transferred to the light guide plate 4 and the liquid crystal display panel 5, so that the light guide plate 4 is excessively deformed by heat, and the liquid crystal display panel 5 has poor color development due to heat. Nothing happens.

In this embodiment, 3 light sources are used as light sources.
Although the mode in which the LEDs 10 are used so as to face the incident surface 8 of the light guide plate 4 has been exemplified, the invention is not limited thereto.
The location where the LEDs 10 are arranged and the number of LEDs 10 to be installed may be appropriately changed depending on conditions such as the size of the LED 10 and the accommodation space of the surface light source device 11. For example, the LEDs 10 may be installed on the other side surfaces 16, 17, 18 of the light guide plate 4.

In this embodiment, the light guide plate 4 having a substantially wedge-shaped cross section has been exemplified.
The invention is not limited to this, and a parallel plate or a light guide plate having another conventionally known cross-sectional shape can be used.

[Second Embodiment] FIGS. 6 to 8 show a second embodiment of the present invention. FIG. 6 is a plan view of the frame 2 constituting the surface light source device 11. 7 is a longitudinal sectional view of the frame 2 cut along the line CC in FIG. 6, and FIG. 8 is a partial sectional view showing an enlarged portion D in FIG.

In the present embodiment, the shape of the bottom wall 6 of the recess 12 of the frame 2 is different from that of the first embodiment, but the basic configuration is the same as that of the first embodiment. Therefore, the same reference numerals are given to the same components as those in the first embodiment, and the duplicate description will be omitted.

That is, the surface light source device 11 according to the present embodiment
The frame 2 of the first embodiment has a bottom wall 6 of the recess 12 instead of the light guide plate support 13 of the first embodiment (see FIGS. 1 to 5).
A plurality of projections 20a and 20b are formed on the light guide plate 3, and the plurality of projections 20a and 20b support the reflection sheet 3, the light guide plate 4, and the liquid crystal display panel 5. Here, protrusion 2
As shown in detail in FIG. 8, reference numerals 0a and 20b denote protrusions 20a and 20b which are in contact with the reflection sheet 3 and each of which has a substantially circular cross-section, and have a contact area between the protrusions 20a and 20b and the reflection sheet 3. Are extremely small, the protrusions 20a, 2
Hard fine dust hardly intervenes between Ob and the reflection sheet 3. Therefore, in this embodiment, the reflection sheet 3 and the light guide plate 4 are also used.
Can be prevented from being damaged by hard fine dust. The fine dust entering between the reflection sheet 3 and the frame 2 is stored in the space between the projections 20a and 20b, and does not damage the reflection sheet 3 or the light guide plate 4.

In this embodiment, the protrusions 20a,
As shown in FIG. 6, the end portion 20b is formed in a rod shape having a substantially semicircular shape, and as shown in FIG. 7 and FIG. Light plate 4
There is no sharp edge portion that damages the image (see FIG. 1).

The projections 20a and 20b are not limited to the above-described embodiment. For example, a plurality of hemispherical projections may be formed on the bottom wall 6 of the frame 2 in a scattered manner.

Third Embodiment FIGS. 9 and 10 show a third embodiment of the present invention. this house,
FIG. 9 is a plan view of the frame 2 constituting the surface light source device 11. FIG. 10 is a longitudinal sectional view of the frame 2 shown by cutting along the line EE in FIG.

In this embodiment, the shape of the bottom wall 6 of the recess 12 of the frame 2 is different from the first and second embodiments, but the basic configuration is the first and second embodiments. Therefore, the same reference numerals are given to the same components as those of the first and second embodiments, and the overlapping description will be omitted.

That is, the surface light source device 11 according to this embodiment
The frame 2 has a plurality of projections 20a and 20b formed on the bottom wall 6 of the recess 12 in addition to the light guide plate support 13 of the first embodiment (see FIGS. 4 and 5). And
The reflection sheet 3 and the light guide plate 4 are supported by the light guide plate support 13 and the plurality of protrusions 20a and 20b. Here, the protrusions 20a and 20b have substantially the same shape as in the second embodiment, and are formed in the counterbore portion 14 of the frame 2.

The frame 2 of the surface light source device 11 according to the present embodiment having such a structure accommodates hard fine dust in the gap in the counterbore portion 14, similarly to the first and second embodiments. Therefore, it is possible to prevent the reflection sheet 3 corresponding to the counterbore portion 14 and the back surface 4a side of the light guide plate 4 from being damaged by fine dust (see FIG. 1).

In this embodiment, the light guide plate support portion 13 supports the reflection sheet 3 and the light guide plate 4 so as to seal the edges on the back surface 4a side, and the projections 20 projecting into the counterbore portion 14.
a and 20b prevent the reflective sheet 3 and the light guide plate 4 from being bent and deformed. Therefore, the surface light source device 11 of the present embodiment can be applied to a case where the large light guide plate 4 has a problem of bending, as well as obtaining the same effects as those of the above embodiments. Then, the shape of the light guide plate 4 and the like can always be maintained in an optimal state, and the illumination quality and the image display quality can be further improved.

[Other Embodiments] Further, as shown in FIG. 11, the light guide plate support 13 of the first and third embodiments is provided.
Are arranged on the bottom wall 6 of the recess 12 of the frame 2 so that the fine dust accommodating space (void) 22 corresponding to the effective light emitting area of the light guide plate 4 is formed on the bottom of the frame 2. It may be formed on the wall 6. That is, the light guide plate support 13 may be formed separately from the frame 2. In this embodiment, the fine dust storage space 22 corresponds to the counterbore portion 14 of the first and third embodiments.

In each of the above embodiments, the gap (1) formed between the bottom wall 6 of the frame 2 and the light guide plate 4
4, 22), an easily deformable filler (elastic material such as sponge or rubber, or a plastic material in the form of clay or gel) may be interposed. With this configuration, even if dust enters the back surface side of the reflection sheet 3, the filler is deformed to reduce the contact load between the dust and the reflection sheet, thereby preventing the light guide plate 4 from being damaged. be able to. In addition, since the filler traps the dust and the movement of the dust can be restricted by the filler, even if the light guide plate 4 is scratched by the dust, the scratch hardly spreads.

In each of the above embodiments, the liquid crystal display panel 5 is exemplified as a member to be illuminated. However, the member to be illuminated is not limited to this. And a prism sheet) are also included in the illuminated member.

Further, in each of the above embodiments, the mode in which the LED 10 is used as the light source has been exemplified. However, the present invention is not limited to this, and a cold cathode tube may be used.

[0041]

As described above, according to the present invention, a gap is formed between the light guide plate and the frame panel so as to at least correspond to the effective light emitting area of the light guide plate. Even if hard fine dust exists between the light guide plate and the frame panel, the fine dust can be accommodated in the gap. Therefore, according to the present invention, it is possible to prevent abnormal light emission from occurring in at least the effective light emitting region of the light guide plate without scarring the effective light emitting region of the light guide plate due to the fine dust, and to achieve high quality image display. Will be possible.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an image display device according to a first embodiment of the present invention.

FIG. 2 is a plan view of the image display device according to the first embodiment of the present invention.

FIG. 3 is a longitudinal sectional view of the image display device cut along the line AA in FIG. 2;

FIG. 4 is a plan view of the frame according to the first embodiment of the present invention.

FIG. 5 is a vertical sectional view of the frame cut along the line BB in FIG. 4;

FIG. 6 is a plan view of a frame according to a second embodiment of the present invention.

FIG. 7 is a vertical cross-sectional view of the frame, taken along line CC of FIG. 6;

FIG. 8 is an enlarged view of a part D in FIG. 7;

FIG. 9 is a plan view of a frame according to a third embodiment of the present invention.

FIG. 10 is a vertical cross-sectional view of the frame, taken along line EE in FIG. 9;

FIG. 11 is a longitudinal sectional view of a frame according to another embodiment of the present invention.

FIG. 12 is a longitudinal sectional view of a conventional image display device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Image display device, 4 ... Light guide plate, 4a ... Back surface, 4
b: outgoing surface, 5: liquid crystal display panel (illuminated member),
6 bottom wall (frame panel), 8 entrance surface (side surface), 10 LED (light source), 11 surface light source device,
13 light guide plate support, 20a, 20b protrusion, 22
…… Small garbage storage space

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04M 1/22 F21Y 101: 02 // F21Y 101: 02 G02F 1/1335 530 F-term (Reference) 2H089 HA40 JA10 QA05 QA08 TA17 TA18 TA20 2H091 FA14Z FA23Z FA41Z FA45Z LA03 LA07 5K023 AA07 BB25 BB26 HH07 MM01 MM07 MM23 MM23 QQ05 RR01

Claims (6)

[Claims] 1. A surface light source device, wherein a frame panel supporting the light guide plate is disposed on a back surface side of the light guide plate, and light of a light source is emitted in a plane through the light guide plate. A surface light source device, wherein a light guide plate supporting portion for supporting a rear edge of the light guide plate is formed so as to protrude more toward the light guide plate than other portions. 2. A surface light source device, wherein a frame panel supporting the light guide plate is disposed on the back side of the light guide plate, and light of a light source is emitted in a plane through the light guide plate. A surface light source device, wherein a plurality of projections are formed to support the rear surface of the light guide plate, and at least the tips of the projections are formed in a substantially semicircular cross section. 3. A surface light source device, wherein a frame panel supporting the light guide plate is disposed on a back surface side of the light guide plate, and light of a light source is emitted in a plane through the light guide plate. A light guide plate supporting portion that supports the back surface side edge of the light guide plate, and a protrusion that supports the back surface side of the light guide plate between the light guide plate support portions are formed, and at least the tip of the protrusion has a substantially semicircular cross section. A surface light source device characterized by being formed in. 4. A surface light source device wherein a frame panel supporting the light guide plate is disposed on the back side of the light guide plate, and light of a light source is emitted in a planar manner through the light guide plate. And a spacer for supporting at least a rear edge of the light guide plate to form a gap between the light guide plate and the light guide plate. 5. The surface according to claim 1, wherein an easily deformable filler is interposed in a gap formed between the frame panel and the light guide plate. Light source device. 6. A surface light source device according to any one of claims 1 to 5, and an illuminated member disposed on an emission surface side of a light guide plate of the surface light source device. Image display device.