JP2003195297A - Back light unit for liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a back light unit of a liquid crystal display device, not generating luminance irregularities. <P>SOLUTION: The back light unit of the liquid crystal display device is provided with a light transmission plate 4 arranged below a liquid crystal panel 10, an optical fiber 6 arranged around the light transmission plate 4 so as to surround the peripheral side face of the light transmission plate 4 over the entire periphery, a light source 5 provided closely to the side face of the light transmission plate 4 for leading an emitted light from both ends of the optical fiber 6 to the inside of the optical fiber 6, and a unit case 1 housing and installing the light transmission plate 4, the optical fiber 6 and the light source 5 in a housing part 2a with an opened upper surface. The light emitted by the light source 5 is passed through the optical fiber 6, led to the entire periphery of the side face of the light transmission plate 4 and made incident inside the light transmission plate and the liquid crystal panel 10 is irradiated therewith. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit of a liquid crystal display device.

[0002]

2. Description of the Related Art As a conventional technique of this kind, there is a structure shown in FIGS. FIG. 4 is a schematic plan view showing a backlight unit of a conventional liquid crystal display device, and FIG. 5 is a side sectional view taken along line II-II of FIG.

As shown in these figures, in the conventional backlight unit, a quadrilateral light guide plate 31 is horizontally housed and installed in the bottom of a unit case 30 whose upper surface is open, and a predetermined area is provided around the light guide plate 31. A plurality of light sources 32 are arranged at intervals of to guide the light emitted from these light sources 32 into the light guide plate 31, and also by utilizing the reflection by the reflection plate 33 arranged on the lower surface of the light guide plate 31, the upper part of the light guide plate 31 The liquid crystal panel 36 arranged in the direction is illuminated.

The light emitted from the light guide plate 31 toward the liquid crystal panel 36 is adjusted by the diffusion plate 34 disposed immediately above the light guide plate 31 so that the brightness becomes uniform, and then on the diffusion plate 34. The light is condensed by the light collecting plate 35 arranged on the lower surface of the liquid crystal panel 36 and is irradiated on the lower surface of the liquid crystal panel 36.

Further, as a backlight unit of a liquid crystal display device having a structure other than the above-mentioned conventional structure, there is one as disclosed in Japanese Patent Application Laid-Open No. 4-157423.

In the backlight unit disclosed in this publication, rod-shaped light sources are provided close to each side of a quadrilateral light guide plate, and the light emitted from these light sources is guided to the light guide plate and at the same time, the light guide plate of this light guide plate is guided. The structure is such that the light is reflected by the reflection plate arranged on the lower surface and is irradiated toward the liquid crystal panel arranged on the light guide plate.

[0007]

In the conventional backlight unit shown in FIGS. 4 and 5, the light emitted from the light source 32 is moved away from the light source 32, that is, toward the center of the light guide plate 31. However, there is a problem that the brightness (light radiated to the back surface of the liquid crystal panel 36) is lowered.

Further, since a plurality of light sources 32 are arranged at predetermined intervals on each side of the light guide plate 31, there is a problem that the light emitted from the light guide plate 31 to the upper surface has uneven brightness. is there. As a method to solve this uneven brightness, the light guide plate
There is a method of increasing the number of light sources 32 around 31 or increasing the brightness of the light sources 32, but in any case, this leads to an increase in the number of parts and power consumption.

Further, a space for arranging the light source 32, a wiring for supplying electric power to the light source 32, and the like are required, which makes it difficult to downsize the backlight unit.

Also, in the backlight unit disclosed in the above-mentioned Japanese Patent Laid-Open No. 4-157423, since light sources are provided around the light guide plate, the number of parts and power consumption increase. In particular, there is a problem that it is difficult to reduce the size of the backlight unit due to the wiring for supplying power to the light source.

[0011]

The present invention has been made in view of the above conventional problems. That is, the backlight unit of the liquid crystal display device of the present invention is arranged around the light guide plate arranged below the liquid crystal panel and the light guide plate so as to surround the peripheral side surface of the light guide plate over the entire circumference. And an optical fiber, a light source that is provided near the side surface of the light guide plate and guides the emitted light from both ends of the optical fiber into the optical fiber, and the light guide plate, the optical fiber, and the light source are housed and installed in a storage unit having an opening on the top A unit case is provided, and the light emitted from the light source is guided to the entire side surface of the light guide plate through the optical fiber so as to enter the light guide plate and illuminate the liquid crystal panel.

According to this structure, the light emitted from one light source is guided to the entire circumference of the side surface of the light guide plate through one optical fiber and is made incident on the light guide plate.

Therefore, the light guide plate can be made to enter the light guide plate uniformly over the entire circumference of the side surface of the light guide plate without breaks. Therefore, the light guide plate due to the difference in the brightness of the light source, the difference in the distance from the light source, etc. The occurrence of uneven brightness can be minimized,
Moreover, the brightness of the surface of the light guide plate can be improved.

Further, by using only one light source, wiring for supplying electric power to the light source can be simplified and the backlight unit can be further downsized.

The backlight unit of the liquid crystal display device of the present invention comprises a light guide plate disposed below the liquid crystal panel,
A light source that is provided close to the side surface of the light guide plate and has a part of the outer peripheral surface facing a part of the side surface of the light guide plate, and a light guide plate that surrounds the peripheral side surface of the light guide plate over the entire circumference. The optical fiber disposed around the light plate and having both ends opposed to the light source, and the unit case for accommodating and installing the light guide plate, the optical fiber, and the light source in a storage portion opened on the upper surface, emits the light source. Irradiating the liquid crystal panel by causing light to directly enter the light guide plate from a part of the side surface of the light guide plate, guide the light to the entire circumference of the side surface of the light guide plate through the optical fiber, and allow the light to enter the light guide plate from the entire circumference of the side surface. It is characterized by doing so.

According to this structure, the light emitted from one light source is directly incident on the light guide plate, and is guided to the entire side surface of the light guide plate through one optical fiber to be incident on the light guide plate.

Therefore, while the light from the light source is directly incident on the light guide plate, the light from the light source can be uniformly incident on the light guide plate evenly over the entire circumference of the side surface of the light guide plate. In addition, it is possible to minimize the occurrence of unevenness in the brightness of the light guide plate due to differences in the brightness of the light source, differences in the distance from the light source, and also to improve the brightness of the surface of the light guide plate. You can

Further, by using only one light source, wiring for supplying electric power to the light source can be simplified and the backlight unit can be further downsized.

Further, in the backlight unit of the liquid crystal display device of the present invention, the light guide plate is provided with a defective portion on a side surface thereof, and the light source is arranged so as to face the defective portion, and the light emitted from the light source is directed to the defective portion. It is characterized in that the light is directly incident on the light guide plate through the optical fiber and is guided to the entire circumference of the side surface of the light guide plate through the optical fiber so that the light enters the light guide plate from the entire circumference of the side surface.

According to this structure, the light source is arranged so as to face the defect portion provided on the side surface of the light guide plate, and a part of the light emitted from the light source can be directly incident on the light guide plate efficiently.
The brightness of the surface of the light guide plate can be further improved.

In the backlight unit of the liquid crystal display device of the present invention, a side reflector is provided on the side of the optical fiber opposite to the light guide plate so as to face the entire circumference of the side. It is characterized in that the plate reflects the light from the optical fiber and makes it enter the light guide plate.

With this structure, the light emitted from the optical fiber can be efficiently incident on the light guide plate side, and the brightness of the surface of the light guide plate can be further improved.

Further, the backlight unit of the liquid crystal display device of the present invention comprises a light guide plate arranged below the liquid crystal panel,
An optical fiber arranged around the light guide plate so as to surround the peripheral side surface of the light guide plate over the entire circumference, a unit case for accommodating and installing the light guide plate and the optical fiber in a storage section having an opening on the upper surface, and the unit. A light source provided outside the case, wherein one end of the optical fiber is led out from the unit case and its tip is opposed to the light source so that the light from the light source passes through the optical fiber to the light guide plate. The feature is that it is guided to the entire side surface.

According to this structure, like the above inventions,
Since the light can be made to enter the light guide plate uniformly over the entire circumference of the side surface of the light guide plate, the difference in the brightness of the light source,
It is possible to minimize the occurrence of unevenness in the brightness of the light guide plate due to the difference in the distance from the light source, and also to improve the brightness on the surface of the light guide plate.

Further, by using only one light source, wiring for supplying electric power to the light source can be simplified, and the backlight unit can be further downsized.

Further, in this configuration, since the light source is provided outside the unit case, maintenance and inspection of the light source can be simplified.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

<First Embodiment> FIG. 1 is a plan view of a backlight unit of a liquid crystal display device according to a first embodiment of the present invention. FIG. 2 is a sectional view taken along line I--I of FIG. It is the side sectional view seen.

In these figures, the reference numeral 1 is a unit case composed of a housing provided with an opening provided on the upper surface of a storage portion 2 having a trapezoidal triangular portion of a baseball home base, A bottom reflector 3 having the same shape as the storage section 2 is laid on the bottom surface of the storage section 2.

Reference numeral 4 denotes a light guide plate housed and installed above the bottom reflector 3 in the unit case 1. The plane shape of the light guide plate is substantially the same as the plane shape of the housing section 2, but the size is the entire outer peripheral side surface. It is formed in such a size that a predetermined space 2a is left between it and the inner peripheral side surface of the storage section 2 along the circumference, and in particular, an arcuate defective section 4a is provided at the center of the side surface of the trapezoidal section.

Reference numeral 5 denotes a hemispherical light source, which is installed between the defective portion 4a and the inner side wall of the accommodating portion 2 so that its spherical surface side faces the defective portion 4a.

Reference numeral 6 denotes a side-light type optical fiber which uniformly emits light from the side, and is formed so as to have the same contour as the inner peripheral wall of the housing 2 and surrounds the side surface of the light guide plate 4. It is housed in the space 2a, and both ends thereof face the light source 5.

Reference numeral 7 denotes a side reflector provided on the side of the optical fiber 6 opposite to the light guide plate 4 along the entire inner peripheral wall of the accommodating portion 2 so as to face the entire side of the side. The light emitted from the optical fiber 6 to the inner peripheral wall side of the housing portion 2 is reflected to the light guide plate 4 side.

Reference numeral 8 denotes a diffuser plate which is arranged on the upper surface of the light guide plate 4 and has an outer shape which is substantially the same as that of the accommodating portion 2 and which is formed to be slightly larger than the light guide plate 4. It has the function of diffusing and adjusting so as to be uniform.

Reference numeral 9 denotes a light collecting plate which is arranged on the diffusing plate 8 and whose outer shape is the same as that of the diffusing plate 8. The light diffused by the diffusing plate 8 is condensed again and arranged on the upper surface. In addition, the lower surface of the liquid crystal panel 10 is focused and irradiated.

Since the present invention is constructed as described above, the light emitted from the light source 5 directly enters the light guide plate 4 from the defective portion 4a of the light guide plate 4 and also passes through the optical fiber 6 to guide the light guide plate 4. The light enters the light guide plate 4 from the side surface of the entire circumference.

At this time, the light emitted outside the outer circumference of the optical fiber 6 is reflected by the side reflector 7 and efficiently guided to the light guide plate 4, and the light emitted below the lower surface of the light guide plate 4 is a bottom reflector. The light emitted from the light source 5 is efficiently radiated from the entire upper surface of the light guide plate 4 toward the liquid crystal panel 10 by being reflected by 3 and efficiently guided to the light guide plate 4.

The light emitted from the light guide plate 4 in the direction of the liquid crystal panel 10 is adjusted by the diffuser plate 8 arranged immediately above the light guide plate 4 so that the brightness becomes uniform, and then on the diffuser plate 8. The light is collected by the light collecting plate 9 arranged in the above and is irradiated on the lower surface of the liquid crystal panel 10.

As described above, in the backlight unit of the first embodiment, the light from the light source 5 is directly incident on the light guide plate 4 and is guided to the entire circumference of the side surface of the light guide plate 4 by one optical fiber 6. Light guide plate 4 all around the side without a break
It can be made to enter uniformly.

Therefore, it is possible to minimize the occurrence of uneven brightness of the light guide plate 4 due to the difference in the brightness of the light source 5, the difference in the distance from the light source 5, and the like. Moreover, the brightness of the surface of the light guide plate 4 can be improved.

<Second Embodiment> FIG. 3 is a plan view of a backlight unit of a liquid crystal display device according to a second embodiment.

In this embodiment, as shown in FIG. 3, the unit case 11 is composed of a casing having a quadrilateral-shaped storage portion 12 opened on the upper surface thereof, and the storage portion 12 is provided on the bottom surface of the storage portion 12.
A bottom reflector (not shown) having the same shape as that of the above is laid.

A light guide plate 13 is housed and installed in the unit case 11 above the bottom reflector. The planar shape of the light guide plate 13 is substantially the same as the planar shape of the accommodating portion 12, but the size is the same as the accommodating portion along the entire outer peripheral side surface.
It is formed in such a size that a predetermined space 12a is left between the inner peripheral side surface of 12 and the inner peripheral side surface.

Reference numeral 14 is a side-light type optical fiber which emits light uniformly from the side, as in the first embodiment.
It is formed so as to form a quadrilateral contour having the same shape as the inner peripheral wall of the housing portion 12, is housed in the space 12a so as to surround the side surface outer periphery of the light guide plate 13, and its one end 14a.
Is led out to the outside of the unit case 11 through an insertion opening 11a provided at one corner of the unit case 11 and faces the light source 15 provided outside the unit case 11. The other end 14b of the optical fiber 14 faces the side surface of the one end 14a at the one corner.

Since the backlight unit of this embodiment is constructed as described above, the light emitted from the light source 15 enters the optical fiber 14 through the one end 14a of the optical fiber 14. Then, the light that has entered the optical fiber 14 is guided to the entire side surface of the light guide plate 13 through the optical fiber 14, and enters the light guide plate 13 from the entire side surface.

At this time, the light emitted outside the outer circumference of the optical fiber 14 is reflected by the side reflector 16 and efficiently guided to the light guide plate 13, and the light emitted below the lower surface of the light guide plate 13 is reflected by the bottom reflector. Thus, the light emitted from the light source 15 is efficiently radiated from the entire upper surface of the light guide plate 13 toward the liquid crystal panel (not shown).

The light emitted from the light guide plate 13 toward the liquid crystal panel is diffused and adjusted by the diffuser plate (not shown) arranged immediately above the light guide plate 13 so that the brightness becomes uniform.
Further, the light is condensed by a light collecting plate (not shown) arranged on the diffusing plate, and the lower surface of the liquid crystal panel is irradiated with the light.

As described above, in the backlight unit of the second embodiment, the light from the light source 15 is directly incident on the light guide plate 13 and is guided to the entire side surface of the light guide plate 13 by one optical fiber 14. The light can be made to enter the light guide plate 13 evenly over the entire circumference of the side surface.

Therefore, it is possible to minimize the occurrence of uneven brightness of the light guide plate 13 due to the difference in brightness of the light source 15, the difference in distance from the light source 15, and the like. Moreover, the brightness of the surface of the light guide plate 13 can be improved.

[0050]

As described above, according to the present invention, 1
The light emitted from one light source is guided to the entire circumference of the side surface of the light guide plate through one optical fiber and is made incident on the light guide plate.

As a result, since the light can be made incident uniformly in the light guide plate over the entire circumference of the side surface of the light guide plate, the brightness of the light guide plate due to the difference in the brightness of the light source, the difference in the distance from the light source, etc. The occurrence of unevenness can be suppressed to a minimum and the brightness of the surface of the light guide plate can be improved.

Further, by using only one light source, wiring for supplying electric power to the light source can be simplified, and the backlight unit can be further downsized.

Alternatively, according to the present invention, the light emitted from one light source is directly incident on the light guide plate and is guided to the entire circumference of the side surface of the light guide plate through one optical fiber to be incident on the light guide plate. .

As a result, the light from the light source can be directly incident on the light guide plate, while the light can be uniformly incident on the light guide slope over the entire circumference of the side surface of the light guide plate, so that the light from the light source can be efficiently guided. It is possible to make it incident on the light plate and minimize the occurrence of uneven brightness of the light guide plate due to the difference in the brightness of the light source, the difference in the distance from the light source, etc.
It is also possible to improve the brightness of the surface of the light guide plate.

Further, by using only one light source, it is possible to simplify the wiring and the like for supplying electric power to the light source, and it is possible to further downsize the backlight unit.

Alternatively, according to the present invention, the light source can be disposed so as to face the defect portion provided on the side surface of the light guide plate, and a part of the light emitted from the light source can be directly incident on the light guide plate efficiently. The brightness of the surface of the light guide plate can be further improved.

Further, according to the present invention, the light emitted from the optical fiber can be efficiently incident on the light guide plate side by the side reflector, and the brightness of the light guide plate surface can be further improved.

According to the present invention, as in the above-mentioned inventions, since the light can be made to enter the light guide plate uniformly over the entire circumference of the side surface of the light guide plate, the difference in the brightness of the light source, the light source It is possible to minimize the occurrence of brightness unevenness of the light guide plate due to the difference in the distance from the light guide plate, and to improve the brightness of the surface of the light guide plate.

Further, by using only one light source, wiring for supplying electric power to the light source can be simplified and the backlight unit can be further downsized.

Furthermore, in this configuration, since the light source is provided outside the unit case, maintenance and inspection of the light source can be simplified.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing a first embodiment of a backlight unit of a liquid crystal display device according to the present invention.

FIG. 2 is a side sectional view of the backlight unit of the same liquid crystal display device taken along line I-I in FIG.

FIG. 3 is a schematic plan view showing a second embodiment of the backlight unit of the above liquid crystal display device.

FIG. 4 is a schematic plan view showing a backlight unit of a conventional liquid crystal display device.

FIG. 5 is a side sectional view of the backlight unit of the conventional liquid crystal display device taken along line II-II in FIG.

[Explanation of symbols]

1 unit case 2 storage 2a space 3 Bottom reflector 4 Light guide plate 5 light sources 6 optical fiber 7 Side reflector 8 diffuser 9 Light collector 10 LCD panel 11 unit case 11a mouth 12 Storage 13 Light guide plate 14 Optical fiber 15 light source 16 Side reflector

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // F21Y 101: 02 F21Y 101: 02

Claims (5)

[Claims] 1. A light guide plate arranged below a liquid crystal panel, an optical fiber arranged around the light guide plate so as to surround a peripheral side surface of the light guide plate over the entire circumference, and a side surface of the light guide plate. A light source that is provided near the optical fiber and guides the emitted light from both ends of the optical fiber into the optical fiber; and a unit case that accommodates and installs the light guide plate, the optical fiber, and the light source in an accommodating portion having an opening on the upper surface. A backlight unit for a liquid crystal display device, characterized in that the emitted light is guided to the entire side surface of the light guide plate through the optical fiber to enter the light guide plate to illuminate the liquid crystal panel. 2. A light guide plate disposed below the liquid crystal panel, and a light source provided adjacent to a side surface of the light guide plate and having a part of an outer peripheral surface opposed to a part of a side surface of the light guide plate. An optical fiber which is arranged around the light guide plate so as to surround the light guide plate around the entire circumference and has both ends facing the light source, and the light guide plate, the optical fiber and the light source are opened on the upper surface. And a unit case that is housed and installed in the housing portion, wherein the light emitted from the light source is directly incident on the light guide plate from a part of the side surface of the light guide plate and is guided to the entire circumference of the side surface of the light guide plate through the optical fiber. A backlight unit for a liquid crystal display device, characterized in that the liquid crystal panel is illuminated by being incident on the light guide plate from the entire circumference of the side surface. 3. The light guide plate is provided with a cutout portion on a side surface thereof, the light source is arranged to face the cutout portion, and light emitted from the light source is directly incident on the light guide plate through the cutout portion and passed through the optical fiber. The backlight unit of a liquid crystal display device according to claim 2, wherein the light guide plate is guided to the entire circumference of the side surface so that the light enters the light guide plate from the entire circumference of the side surface. 4. A side reflector is provided on the side of the optical fiber opposite to the light guide plate so as to face the entire circumference of the side, and the side reflector reflects the light from the optical fiber. The backlight unit of the liquid crystal display device according to claim 1, wherein the backlight unit is made incident on the light guide plate. 5. A light guide plate arranged below the liquid crystal panel, an optical fiber arranged around the light guide plate so as to surround a peripheral side surface of the light guide plate over the entire circumference, and the light guide plate and the optical fiber. And a light source provided outside the unit case, wherein one end of the optical fiber is led out from the unit case and the tip thereof serves as the light source. A backlight unit of a liquid crystal display device, characterized in that light from the light source is guided to the entire circumference of the side surface of the light guide plate by being opposed to each other.