JP2001249621A - Illumination unit and liquid crystal display device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illumination unit which improves the assembling characteristic of lead wires connected to a light source and a liquid crystal display device having the same. SOLUTION: The illumination unit UT which has the light source 2, a light transmission plate 1 for guiding the light from the light source 2 and a metallic casing 9 arranged below the light transmission plate 1 and in its lateral direction and is formed with a display area above the light transmission plate 1 is arranged with the leas wires 7 connected to the light source 2 between the flank of the light transmission plate 1 and the casing 9 and is reduced in the disengagement of the lead wires 7 by the projection to the inner side disposed on the flank of the casing 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting unit having a light source disposed on a side surface of a light guide plate and a liquid crystal display device having the same.

[0002]

2. Description of the Related Art In recent years, display devices for information devices, such as notebook personal computers and word processors, and display devices for video devices, such as portable televisions, video movies, and car navigation systems, have become lighter and thinner.
Liquid crystal display devices have come to be widely used taking advantage of the feature of low power consumption. Further, in order to realize a bright display screen in these liquid crystal display devices, there are many configurations in which illumination light is applied from behind a display element by a built-in illumination unit.

In this illumination unit, an edge light system in which a light guide plate is placed on the back surface of a display element and a line light source such as a fluorescent discharge tube is arranged on an end face of the light guide plate is excellent in thickness reduction and uniformity of luminance of a light emitting surface. As a backlight system of a liquid crystal display device used in a notebook personal computer or the like, an edge light system is often employed in order to give priority to thinness. In a liquid crystal display device used for a portable television, a car navigation system, or the like, an edge light method using two or more fluorescent discharge tubes or an L-shaped fluorescent discharge tube or In many cases, an edge light method using a U-shaped fluorescent discharge tube is adopted.

The fluorescent discharge tube is driven by high-frequency alternating current to emit light, and lead wires are connected to both ends of the fluorescent discharge tube to supply a predetermined drive voltage to the fluorescent discharge tube from outside. A connector is provided at the tip of these two leads,
Connected to an external inverter.

In the edge light system, a fluorescent discharge tube is arranged outside the light guide plate. In order to further enhance the portability and space saving characteristics of a liquid crystal display device,
The point is how to arrange the members such as the light guide plate, the fluorescent discharge tube, and the lead wire compactly in the lighting unit and the liquid crystal display device.

FIG. 4 shows a conventional edge light type illumination unit UT using a fluorescent discharge tube. The lighting unit UT has a flat transparent light guide plate 1 for transmitting light, and an L-shaped bent L-shape on two of the four sides of the light guide plate 1.
A fluorescent discharge tube 2 shaped like a letter and a reflection sheet 3 for guiding light emitted from the fluorescent discharge tube 2 to an end face D1 of the light guide plate 1 are arranged. The light guide plate 1, the fluorescent discharge tube 2 and the like have a housing 9 formed of metal below the light guide plate and a housing 1 formed of resin above the light guide plate.
By being held by 0, an illumination unit is formed.

[0007] The reflection sheet 3 has a role of returning the light going out of the light guide plate 1 back into the light guide plate 1 and increasing the illumination light coming out of the light exit surface. As the reflection sheet 3, a white resin film having a high reflectance is used.

The reflective sheet 3 is made of a double-sided tape while separating a portion around the fluorescent discharge tube 2 (this portion may be referred to as a “reflector”) and a portion on the back side of the light guide plate 1. Although there is also a configuration in which the two are adhered at 6, the integrated configuration shown in FIG. 4 has the advantage that the lighting unit UT can be made thinner and the cost and the number of assembly steps can be reduced.

On the irradiation surface side of the light guide plate 1, light correction sheets 4 and 5 are arranged. The light correction sheets 4 and 5 include a diffusion sheet, a prism sheet, and the like. By arranging an arbitrary number of sheets having various specifications as necessary, the light emitted from the light guide plate is diffused, and the like. To achieve uniformity and high brightness.

Both ends of the fluorescent discharge tube 2 are connected by soldering or the like to a lead wire 7 connected to a power supply unit such as an inverter for generating a high-frequency alternating current, and a voltage necessary for lighting the fluorescent discharge tube 2 is provided. Is applied. Generally, a high voltage is required to light the fluorescent discharge tube 2, and a cylindrical rubber holder 8 made of an insulator such as rubber is attached to cover the exposed portion of the lead wire 7. The high voltage of the exposed part of the lead wire 7 is insulated.

The lead wire 7 is inserted and held in a lead wire fixing groove L provided in the housing 10 and is provided on a part of the side surface of the housing 9 where the fluorescent discharge tube 2 is not provided. The opening H is drawn out.

[0012]

However, in the conventional illumination unit UT and the liquid crystal display device LD having the above-described structures, when the lead wire 7 is inserted into the lead wire fixing groove L provided in the housing 10, 10 has poor rigidity because of lack of rigidity. Further, at this time, resin dust is generated from the housing 10, and the portion of the lead wire fixing groove L of the housing 10 is deformed and the light correction sheets 4 and 5 are damaged. When the thickness of the portion of the lead wire fixing groove L is increased so that the housing 10 has sufficient rigidity, a sufficient space for that is required, and the size of the illumination unit with respect to the image display area increases.

The present invention solves the above-mentioned conventional problems, and has a simple structure using members constituting an illumination unit and a liquid crystal display device, but also has good assemblability for a lead wire 7 connected to a light source. It is an object of the present invention to provide a compact lighting unit that can be stored and that further reduces the generation of dust during storage and damage to members of the display area such as the light correction sheets 4 and 5 and a liquid crystal display device including the same.

[0014]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a light source, a light guide plate for guiding light from the light source, and a metal housing disposed below and on the side of the light guide plate. In a lighting unit having a display area above the light guide plate, a lead wire connected to the light source is arranged to be sandwiched between the light guide plate side surface and the housing,
The detachment of the lead wire is suppressed by the inward projection provided on the side surface of the housing.

[0015] Thus, while having a simple configuration using members constituting the lighting unit and the liquid crystal display device,
The lead wire connected to the light source can be stored with good assemblability,
Further, it is possible to obtain a compact illumination unit and a liquid crystal display device including the compact illumination unit, in which generation of dust during storage and damage to members in a display area such as a light correction sheet are further reduced.

[0016]

An embodiment of the present invention will be described below with reference to the drawings.

In this embodiment, as shown in FIGS. 1 and 2, a light source 2, a light guide plate 1 on a flat plate for transmitting light from the light source 2, and a back surface of the light guide plate 1 are arranged. The illumination unit UT includes a reflective sheet 3 and housings 9 and 10 provided with a gap surrounding the reflective sheet 3. Lead wires 7 are connected to both ends of the fluorescent discharge tube 2 for supplying a predetermined drive voltage from the outside. Connectors are provided at the ends of these two lead wires, and are connected to an external inverter. The light source 2 has an L-shaped fluorescent discharge tube 2 that is driven by a high-frequency AC (40 to 100 kHz) and emits light on two of the four sides of the light guide plate 1 (“L-shaped fluorescent light”). Called "discharge tube"). Fluorescent discharge tube 2
Are provided between the reflection sheet 3 and the housing 9 on two sides of the side E2 where the light source 2 is not disposed.
Are provided. The fluorescent discharge tube 2
The distances W1 and W2 from the outside of the lighting unit to the effective display area are shorter on the two sides of the side E2 where the fluorescent discharge tube 2 is not disposed than on the two sides of the side E1 where the fluorescent discharge tube 2 is disposed (FIG. 2). W1 <W2).

A lead wire 7 for supplying a voltage from the outside is connected to both ends of the fluorescent discharge tube 2, and a connection portion between the lead wire 7 and the fluorescent discharge tube 2 is covered by a rubber holder 8. I have. As shown in FIG. 2, the lead wire 7 is disposed without a gap in a gap M between the side surface of the light guide plate 1 and the housing 9, and the side E of the housing 9 where the fluorescent discharge tube 2 is not disposed.
It is held by a plurality of inward projections K provided on the side surface 2 and is drawn out through an opening H provided on the side surface of the side E2 of the housing 9 where the fluorescent discharge tube 2 is not arranged.
Since the protrusion K is held in contact with the upper part of the lead wire 7,
It is possible to prevent the lead wire 7 inserted once at the interval M from coming off.

Such a lighting unit UT includes a light guide plate 1
After assembling the reflection sheet 3 and the fluorescent discharge tube 2 and storing them in a box-shaped housing 9,
2 and 3 are held. The housing 9 of the present embodiment holds the light guide plate 1 from the outer peripheral side and the lower side. Further, in combination with the housing 9 and the housing 10 fitted from the upper side, the lighting unit UT is provided. Complete. Such a case 9,
There are various types of the liquid crystal display 10, and there is a liquid crystal display 10 that simultaneously holds the liquid crystal panel 11 disposed above the light guide plate 1. Then, as shown in FIG. 3, this lighting unit UT
, A liquid crystal panel 11 is mounted thereon, and a front cover 12 is mounted thereon, thereby completing the liquid crystal display device LD. The front cover 12 is also a kind of housing.

The light guide plate 1 is formed of a material such as acrylic having an optimum optical characteristic represented by a transmittance and a refractive index necessary for light transmission. A dot pattern or a groove pattern (not shown) whose shape is changed according to the distance from the fluorescent discharge tube 2 is provided on the back surface of the light guide plate 1,
By the light correction sheets 4 and 5 provided on the front side, the light emitted from the illumination unit UT is equalized and the luminance is increased. The light emitted from the fluorescent discharge tube 2 is transmitted to the light guide plate 1.
And is guided to the inside.

The reflection sheet 3 is made of a white resin film having a high reflectance, and is formed by bending the back surface of the reflection sheet 3 into a U-shape. That is, one side of the reflection sheet 3 is bent so as to surround the fluorescent discharge tube 2, and the double-sided tape 6 is attached to the surface of the light guide plate 1.
The side E2 on which the fluorescent discharge tube 2 is not disposed is bent along the light guide plate end face D2. By being bent at the light guide end face D2,
The light exiting from the light guide plate end face D2 is returned into the light guide plate 1 again, and serves to increase the light emitted from the surface of the light guide plate 1. In addition, the reflection sheet 3 on the back surface of the light guide plate 1 has a role of returning the light that goes out from the back surface of the light guide plate 1 back into the light guide plate 1 and increasing the illumination light that is emitted. As the type of the reflection sheet 3, in addition to the above-described integrated structure,
A part around the fluorescent discharge tube 2 (this part is referred to as a “reflector”).
The light guide plate 1 may be separated from the rear surface side, but the present invention is also applicable to such a reflection sheet 3.

In the embodiment described above, the case where the present invention is applied to the lighting unit using the L-shaped fluorescent discharge tube 2 has been described. It can be widely applied to lighting units.

[0023]

As described above, according to the lighting unit and the liquid crystal display device of the present invention, the lead wire connected to the light source can be stored with good assemblability, and the generation of dust at the time of storage and the generation of the light correction sheet and the like can be achieved. Damage to members in the display area can be further reduced, which is of great industrial value.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a lighting unit according to an embodiment.

FIG. 2 is a plan view showing a configuration of a lighting unit according to the embodiment.

FIG. 3 is a cross-sectional view illustrating a configuration of a liquid crystal display device in which the lighting unit of the embodiment is incorporated.

FIG. 4 is a cross-sectional view showing a configuration of a conventional lighting unit.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 light guide plate 2 fluorescent discharge tube (light source) 3 reflection sheet 4, 5 light correction sheet 6 double-sided tape 7 lead wire 8 rubber holder 9, 10 housing 11 liquid crystal panel 12 front cover D 1, D 2 entrance end face of light guide plate E 1 light source E2 Side where light source is not arranged H Opening of housing K Projection L Lead wire fixing groove M Distance between reflective sheet and housing W1, W2 Distance from outside of lighting unit to effective display area UT Lighting unit LD Liquid crystal display

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H091 FA23Z FA41Z LA02 LA07 LA11 LA16 5G435 AA11 AA17 BB12 EE05 EE27 EE41 FF08 GG24

Claims (2)

[Claims] An illumination unit comprising: a light source; a light guide plate for guiding light from the light source; and a metal housing disposed below and on a side of the light guide plate, and a display area is provided above the light guide plate. In the above, the lead wire connected to the light source was disposed so as to be sandwiched between the light guide plate side surface and the housing, and the inward projection provided on the side surface of the housing prevented the lead wire from coming off. Lighting unit. 2. A liquid crystal display device comprising the lighting unit according to claim 1.