JP2002357823A - Backlight for liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of luminescent points due to a light shielding tape in a side backlight. SOLUTION: In a backlight for liquid crystal element in which the light transmission plate 1 and light sources 2 irradiating the light transmission plate 1 with rays of light are included, circular recessed parts 1a for inputting rays of light are formed at the side face of the plate 1 and the light sources 2 are housed in the recessed parts 1a and light shielding tape 4 having a width equal to or larger than the depth of the recessed parts 1a is adhered to the liquid crystal panel-side upper surface of the plate 1 with adhesive material 5 so as to cover portions 1b of the upper surface of the plate 1 which are positioned at the front of the recessed part 1a and the recessed part 1a, the adhesive material 5 is provided by avoiding the portions 1b of the upper surface of the plate 1 which are positioned at the front of the recessed parts 1a for inputting rays of light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sidelight type backlight used in a liquid crystal display device, and more particularly to a technique for preventing a bright spot from being noticeable by a light shielding tape.

[0002]

2. Description of the Related Art A transmissive or transflective liquid crystal display device is provided with a backlight (illumination device) so that a bright display can be obtained even in a dark place. The backlight is
Light sources are located directly below the light guide plate, and side light devices are located on the side of the light guide plate. ,
The side light type is adopted exclusively.

As shown in an exploded perspective view of a main part of FIG. 5 and a cross-sectional view of FIG. 6, a sidelight type backlight has a light guide plate (light guide) 1 made of, for example, an acrylic resin as a basic configuration. A light source 2 disposed on the side of the light guide plate 1.

A light guide plate 1 is arranged on the back side of a liquid crystal panel (not shown).
Light reflector 3 for directing light from the LCD panel side
Is provided. Although not shown, a light diffusion plate for uniformly dispersing the light from the light source 2 is provided on the upper surface side of the light guide plate 1.

In this sidelight type backlight, a light emitting diode (LED) is generally used as the light source 2. However, in order to improve the light incidence efficiency with respect to the light guide plate 1 and to reduce the space for arranging the light source 2, the light guide plate 1 is not used. An arc-shaped concave portion 1a for light incidence is formed on the side surface, and an LED as a light source 2 is housed in the concave portion 1a.

If this state is maintained, a part of the light from the light source 2 may be directly radiated to the liquid crystal panel, causing luminance unevenness. ing.

In this case, in order to completely cover the light source 2, the width of the light shielding tape 4 is set to be equal to or greater than the depth of the concave portion 1 a, and the light shielding tape 4 is connected to the light guide plate 1 via the double-sided adhesive tape 5. It is stuck on the upper surface.

[0008]

According to the wide light-shielding tape 4, a part 1b of the upper surface of the light guide plate located in front of the concave portion 1a is also covered with the light-shielding tape 4. The following problems occur.

That is, as shown in the sectional view of FIG. 6, the double-sided adhesive tape 5 existing between the portion 1b of the upper surface of the light guide plate and the light shielding tape 4 serves as a light guide, as shown in FIG. Then, a bright point 2a of the light source 2 is generated on the edge of the light shielding tape 4. The luminescent spot 2a is noticeably observed in a so-called eyeball shape, particularly when the edge of the light-shielding tape 4 is viewed from an oblique direction, and may cause uneven brightness.

[0010]

In order to solve the above-mentioned problems, the present invention comprises a light guide plate located on the back side of a liquid crystal panel, and a light source for irradiating the light guide plate with light. An arc-shaped concave portion for light incidence is formed on the side surface, the light source is accommodated in the concave portion, and a light shield having a width equal to or greater than the depth of the concave portion is provided on the upper surface of the light guide plate on the liquid crystal panel side. In a liquid crystal display element backlight in which a tape is adhered via an adhesive so as to cover a part of the upper surface of the light guide plate located in front of the recess and the recess, the adhesive is provided in front of the recess. The light guide plate is provided so as to avoid a part of the upper surface of the light guide plate.

In the present invention as well, a light-shielding tape wider than the depth of the light-receiving recess is used, and the light-shielding tape covers a part of the upper surface of the light guide plate located in front of the light-receiving recess. Since the adhesive serving as a light guide does not exist on a part of the upper surface of the light guide plate, no bright point of the light source appears on the edge of the light shielding tape.

In many cases, a plurality of light-receiving recesses are formed at predetermined intervals in a light guide plate, and a light source is housed in each of the recesses. A light guide plate having a length substantially equal to one side of the light incident side of the light guide plate is used.

In the present invention, in order to attach the long light-shielding tape to the light guide plate, it is necessary to provide an adhesive at both ends of the light-shielding tape, avoiding the light incident concave portion and a part of the upper surface of the light guide plate located in front of the concave portion. Alternatively, the adhesive may be provided along the length direction of the light-shielding tape avoiding a part of the upper surface of the light guide plate located in front of the light incident concave portion.

It is preferable that the light-shielding tape is pressed from above by a certain means, for example, a liquid crystal panel, to make the light-shielding tape and the light guide plate adhere to each other. Also, a double-sided adhesive tape is suitable for the adhesive,
An adhesive liquid may be used.

[0015]

Next, an embodiment of the present invention will be described. FIG. 1 is an exploded perspective view showing an example of the embodiment.
FIG. 2 is a sectional view of the main part. Note that, in this embodiment, the same reference numerals are used for components that may be the same as or may be regarded as the same as the conventional example described above.

According to this embodiment, two arc-shaped concave portions 1a for light incidence are formed on one side of the light guide plate 1, and a light source 2 composed of a light emitting diode is housed in each of the concave portions 1a. A light shielding tape 4 is provided on the upper surface of the light guide plate 1 so as to cover the light source 2, and a light reflection plate 3 is provided on the bottom surface side of the light guide plate 1.

Also in this embodiment, the width W of the light-shielding tape 4 is larger than the depth D of the light-receiving recess 1a. The length L of the light-shielding tape 4 is substantially the same as one side of the light guide plate 1 so that the two light sources 2 can be covered at the same time. A double-sided adhesive tape 5 is provided.

Therefore, according to the light shielding tape 4,
Not only the light incident recess 1a but also a part 1b of the upper surface of the light guide plate located in front of the light incident recess 1a is covered. Are provided only at both ends.

That is, the double-sided adhesive tape 5 is provided at both ends of the light-shielding tape 4 so as to avoid the light incident concave portion 1a and a part 1b of the upper surface of the light guide plate located in front of the concave portion 1a.
Since the double-sided adhesive tape 5 acting as a light guide does not exist on a portion 1b of the upper surface of the light guide plate located in front of the light incident concave portion 1a, no bright point of the light source 2 appears on the edge of the light shielding tape 4.

As shown in another embodiment of FIG. 3,
The double-sided adhesive tape 5 may be provided along the length direction of the light-shielding tape 4 avoiding only a part 1b of the upper surface of the light guide plate located in front of the light-receiving concave portion 1a, and as shown in FIG. The double-sided adhesive tape 5 may be provided at an intermediate portion of the light shielding tape 4 so as to avoid the incident concave portion 1a and the portion 1b of the upper surface of the light guide plate located in front of the concave portion 1a.

In short, in the present invention, it is sufficient that the double-sided adhesive tape 5 acting as a light guide does not exist on the portion 1b of the upper surface of the light guide plate located in front of the light-receiving concave portion 1a. It is preferable that the portion presses the light-shielding tape 4 from above with some means, for example, a liquid crystal panel, to bring the light-shielding tape 4 and the light guide plate 1 into close contact with each other. In addition, although the double-sided adhesive tape 5 is suitable for the adhesive, an adhesive liquid may be used. Further, the adhesive may be what is called an adhesive.

[0022]

As described above, according to the present invention,
Including a light guide plate of a liquid crystal panel and a light source for irradiating the light guide plate with light, an arc-shaped light incident concave portion is formed on a side surface of the light guide plate, and the light source is housed in the concave portion. Along with the light guide plate, a light-shielding tape having a width equal to or greater than the depth of the recess is provided with an adhesive material on the upper surface of the light guide plate on the liquid crystal panel side so as to cover the recess and a part of the light guide plate upper surface located in front of the recess. In the backlight for a liquid crystal display element that is adhered through the light guide plate, the adhesive is provided so as to avoid a part of the upper surface of the light guide plate located in front of the light incident recess, so that the “eyeball” of the light source "Like" bright spots can be prevented from appearing.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an example of an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of the embodiment.

FIG. 3 is a perspective view showing a modification of the embodiment.

FIG. 4 is a perspective view showing another embodiment of the present invention.

FIG. 5 is an exploded perspective view showing a conventional example.

FIG. 6 is a sectional view of a main part of the conventional example.

FIG. 7 is a perspective view for explaining the problem of the conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 light guide plate 1 a concave portion for light incidence 1 b part of upper surface of light guide plate 2 light source 3 light reflection plate 4 light shielding tape 5 double-sided adhesive tape

Claims (3)

[Claims] 1. A light guide plate positioned on the back side of a liquid crystal panel, and a light source for irradiating the light guide plate with light, wherein an arc-shaped light incident concave portion is formed on a side surface of the light guide plate, The light source is accommodated in the recess, and a light-shielding tape having a width equal to or greater than the depth of the recess is provided on the upper surface of the light guide plate on the liquid crystal panel side. In a backlight for a liquid crystal display element adhered via an adhesive so as to cover a part of the upper surface of the light plate, the adhesive is provided so as to avoid a part of the upper surface of the light guide plate located in front of the concave portion. A backlight for a liquid crystal display element. 2. The light-shielding tape has a length substantially equal to one side of the light guide plate on the light incident side, and the adhesive material covers the recess and a part of the upper surface of the light guide plate located in front of the recess. 2. The backlight for a liquid crystal display device according to claim 1, wherein the backlight is provided at both ends of the light-shielding tape so as to be avoided. 3. The light-shielding tape has a length substantially equal to one side of the light guide plate on the light incident side, and the adhesive material avoids a part of the upper surface of the light guide plate located in front of the recess. 2. The backlight for a liquid crystal display device according to claim 1, wherein the backlight is provided along a length direction of the light shielding tape.