JPH11133401A - Liquid crystal display device with back light unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a back light unit capable of obtaining a stable optical characteristic and easily substituting a light source and a liquid crystal display device provided with the back light unit. SOLUTION: The back light unit 12 for the liquid crystal display device has a light guiding plate 26, a supporting frame 24 for holding an optical sheet and a light source unit 31 fitted to the frame 24. The unit 31 has a reflection film, a cold cathod-ray tube(CRT) and a pair of holders 44 for supporting both the ends of the CRT and these components are fitted to a metallic protection covers 46 (46a, 46b) as a unit. A connection cable 60a led out from each holder 44 is engaged with an engaging groove 48 formed on the cover 46 to position it. The unit 31 is detachably held by the supporting frame 24 by engaging engagement projections 42 formed on the frame 24 with engaging grooves 52 formed on the cover 46.

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, and more particularly, to a backlight unit having an edge lamp type back light source and a liquid crystal display device having the same.

[0002]

2. Description of the Related Art As an electronic apparatus, for example, a liquid crystal display device provided in a portable personal computer or the like includes a liquid crystal display panel and a backlight unit provided so as to overlap the liquid crystal display panel. .

Generally, a backlight unit includes a flat light guide plate, a cold cathode tube as a light source, a light source holder, a reflection film, a protective cover, a frame, and the like. The cold cathode tube is disposed to face one end surface of the light guide plate, and is attached to the frame via a light source holder. The reflection film is arranged so as to surround the cold cathode tube, one end of which is adhesively fixed to the light guide plate, and the other end of which is in contact with the light guide plate while being held down by the protective cover. And the light from the cold cathode tube is
The light enters the light guide plate directly or after being reflected by the reflection film, and is guided by the light guide plate to the entire surface of the liquid crystal display panel.

[0004]

However, in the above-mentioned backlight unit, since one end of the reflection film is pressed against the light guide plate by the protection cover, the cold cathode tube and the reflection film may be pressed by the protection cover. Fluctuates. In a backlight unit using a back light source, the positional relationship between the cold cathode tubes and the reflection film is important, and the optical characteristics of the backlight unit become unstable.

Further, when replacing the light source, it is necessary to remove the protective cover from the frame and then remove the light source from the frame and the light source holder for replacement, which makes the replacement operation troublesome.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide a backlight unit capable of obtaining stable optical characteristics and easily replacing a light source, and a liquid crystal display device having the same. is there.

[0007]

In order to achieve the above object, a backlight unit according to the present invention comprises a frame supporting a light guide plate, and a frame fixed to the frame and connected to one end face of the light guide plate. And a light source unit detachably attached to the frame and positioned adjacent to one end surface of the light guide plate and the first reflection film, wherein the light source unit is attached to the frame. A protective cover made of metal, a light source attached to the protective cover via a pair of holders and facing the first reflective film, and a second reflective film attached to the protective cover facing the light source. It is characterized by having.

The light source is formed in an elongated tube extending along one end surface of the light guide plate, and the holder is provided on a holder main body holding both ends of the light source and a protective cover extending from the holder main body. An engaging protrusion that is detachably engaged, the protective cover has an inner surface facing the light source, and the second reflective film is fixed to an inner surface of the protective cover.

According to the backlight unit of the present invention, the protective cover has an engagement groove formed on an outer surface thereof and extending between the pair of holders, and each of the holders is led out of the holder main body. A connection cable having a connection cable, the connection cable led out from one of the holder main bodies is routed to the other holder main body side and is positioned by engaging with the engagement groove of the protective cover, and the protective cover is interposed therebetween. It faces the light source.

According to the backlight unit having the above structure, the light source, the holder, and the reflection film are fixed to the metal protective cover to form a unit. Therefore, the positional relationship between the light source and the reflection film is kept constant, stable optical characteristics can be obtained, and the light source can be replaced for each unit, thereby simplifying the replacement work.

Further, a liquid crystal display device according to the present invention includes a liquid crystal display panel, and a backlight unit disposed to face the liquid crystal display panel, and the backlight unit includes a frame supporting a light guide plate. A first reflection film fixed to the frame and connected to one end surface of the light guide plate; and a first reflection film detachably attached to the frame and positioned adjacent to one end surface of the light guide plate and the first reflection film. A light source unit. The light source unit includes a metal protective cover attached to the frame, a light source attached to the protective cover via a pair of holders, facing the first reflection film, and a light source facing the light source. A second reflective film attached to the protective cover,
It is characterized by having.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a liquid crystal display according to an embodiment of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the liquid crystal display device includes a liquid crystal display panel 10 and an edge light type backlight unit 1.
2 and the holding frame 14 are laminated. The liquid crystal display panel 10 includes a rectangular array substrate 16 and a counter substrate 18, and liquid crystal molecules (not shown) sealed between the substrates. The array substrate 16 includes a plurality of TCs.
A drive circuit board 22 is connected via a P (tape carrier package) 20.

As shown in FIGS. 1 to 3, the backlight unit 12 includes a rectangular frame-shaped support frame 24, a light guide plate 26, a plurality of, for example, two optical sheets 28, 30,
And an optical unit 31. Support frame 2
Reference numeral 4 is made of, for example, a synthetic resin, and a rectangular mounting portion 36 is formed by its inner peripheral edge. Light guide plate 26
Is formed of, for example, an acrylic plate and is formed in a rectangular shape having substantially the same size as the mounting portion 36. Similarly, the optical sheets 28 and 30 are also formed in a rectangular shape having substantially the same size as the mounting portion 36.

The optical sheet 28 is made of a diffusion sheet, and the optical sheet 30 is made of, for example, a prism sheet. The optical sheets 28 and 30 and the light guide plate 26 are stacked in this order, and the support frame 24 is
The mounting portion 36 is mounted on the mounting portion 36.

As shown in FIGS. 2, 3, 5 and 6, the support frame 24 is formed with a lamp receiving groove 38 extending along one side edge thereof. The lamp housing groove 38 has a substantially fan-shaped cross section. Then, one end surface 26 a of the light guide plate 26 is exposed in the lamp housing groove 38. A first reflection film 40 is attached to the inner surface of the lamp housing groove 38 over substantially the entire length in the longitudinal direction.
6 faces one end surface 26a. Further, a plurality of, for example, three engaging projections 4 are provided on a side surface 24a extending parallel to and adjacent to the lamp accommodating groove 38 in the side surface of the support frame 24.
2 are protruded at predetermined intervals.

On the other hand, the light source unit 31 is detachably attached to the support frame 24 while being attached to the lamp accommodating groove 38. As shown in FIGS. 2 to 6, the light source unit 31 includes an elongated cold cathode tube 32 as a light source,
A pair of holders 44 respectively holding both ends of the cold cathode tube 32 and electrically connected to both ends of the cold cathode tube
And The cold cathode tube 32 is detachably attached to a metal protective cover 46 via a pair of holders 44.

The protective cover 46 is attached to the support frame 24.
And has first, second, and third side walls 46a, 46b, 46c orthogonal to each other, and is formed in a substantially U-shaped cross-sectional shape as a whole.

An engagement groove 48 is formed on the outer surface of the second side wall 46b, and extends over the entire length of the protective cover 46 in the longitudinal direction. Thus, two engagement grooves 50a and 50b are formed on the inner surface side of the second side wall 46b with the engagement groove 48 interposed therebetween. In addition, positioning holes 51 are formed at both ends in the longitudinal direction of the second side wall 46b, and open to the engagement grooves 50a. Furthermore, the second side wall 46b has
The second reflection film 47 is stuck over the entire length except for both ends in the longitudinal direction of the side wall.

The first side wall 46a has an L-shaped fitting groove 5 which can be engaged with the engaging projection 42 on the support frame 24 side.
2 are formed. Further, the third side wall 46c is cut and raised at a right angle outwardly, except for both ends in the longitudinal direction, and forms a contact portion 46d parallel to the second side wall 46b. Furthermore, both ends in the longitudinal direction constitute partitioning portions 46e that can abut on one end surface 26a of the light guide 26.

As shown in FIGS. 3 to 6, each holder 4
Reference numeral 4 denotes a holder main body 54 having a substantially fan-shaped cross section corresponding to the lamp accommodating groove 38, a fitting projection 55 extending from the holder body 54, and a positioning pin projecting from an extension end of the fitting projection. And 56 are integrally formed. From the pair of holder bodies 54, connection cables 60a and 60b for supplying power to the cold cathode tubes 32 are led out, respectively.

Each end of the cold cathode tube 32 is connected to a holder body 54.
The connection cables 60a, 60
b. And a pair of holders 4
4, the fitting protrusion 55 is fitted into the engaging groove 50a of the protective cover 46, and the positioning pin 56 is fitted into the positioning hole 51 of the protective cover, thereby providing a predetermined position, that is, It is detachably attached to both ends in the longitudinal direction.

Thus, the cold-cathode tube 32 is held inside the protective cover 46 so as to face the second reflection film 47, and extends in parallel with the protective cover. The connection cable 60a led out of the one holder 44 is fitted in the engagement groove 48 of the protection cover 46, and is routed to the opposite side while being held at a predetermined position by the protection cover.

The light source unit 31 configured as described above
When the light source unit is attached to the support frame 24, the entire light source unit is moved toward the support frame 24 with the fitting grooves 52 of the protective cover 46 being aligned with the engagement protrusions 42 of the support frame 24, respectively. Are engaged with the corresponding fitting grooves 52, and the holder main bodies 54 of the pair of holders 44 are inserted into the lamp accommodating grooves 38 of the support frame 24. Further, by sliding the entire light source unit 31 in the longitudinal direction of the cold cathode tube 32, the support frame 24
Are fitted in the fitting grooves 52 of the protective cover 46. As a result, the light source unit 31 is
At a predetermined position.

In the mounted state, the protective cover 46 of the light source unit 31 has the first side wall 46a in contact with the side surface 24a of the support frame 24 and the contact portion 46d in contact with the back surface of the light guide plate 26. It is attached to the support frame 24. At the same time, the partition 4 of the protective cover 46
6e are in contact with both ends of one end surface 26a of the light guide plate 26, respectively. In addition, the cold cathode tube 32 is opposed to one end surface 26a of the light guide plate 26 in parallel with a predetermined interval.
The first and second reflection films 40 and 47 are continuous with each other, and face the peripheral surface of the cold cathode tube 32 other than the surface facing the light guide plate 26.

As shown in FIG. 1, the liquid crystal display panel 10
Is the backlight unit 12 configured as described above.
And is adjacently opposed to the optical sheet 30. Further, the holding frame 14 is formed in a rectangular shape, and is disposed so as to overlap the peripheral portion of the liquid crystal display panel 10. The holding frame 14 is fixed to the support frame 24 by screwing or the like, so that the liquid crystal display panel 10 is fixed to the support frame 24 while being sandwiched by the holding frame 14.

During operation of the liquid crystal display device, part of the light emitted from the cold-cathode tube 32 directly enters the light guide plate 26 from one end surface 26a of the light guide plate 26, and the rest is subjected to the first and second reflections. After being reflected by the films 40 and 47, the light enters the light guide plate 26 through one end surface 26a. The incident light propagates through the entire light guide plate 26 and is further guided through the optical sheets 28 and 30 to the entire surface of the liquid crystal display panel 10.

When the cold cathode tube 32 of the light source unit 31 is replaced, the protective cover 46 is slid in the width direction of the light guide plate 26 and then pulled out in a direction perpendicular to the surface of the light guide plate 26, thereby protecting the light guide plate 26. The engagement between the fitting groove 52 of the cover and the engagement protrusion 42 of the support frame 24 is released, and the entire light source unit 31 is removed from the support frame 24. After that, the holder 44 can be replaced by removing the holder 44 from the protective cover 46 and removing the cold cathode tube 32 from the holder 44. The entire light source unit 31 may be replaced.

According to the liquid crystal display device configured as described above, the cold cathode tube 32, the holder 44, and the second reflection film 47 of the backlight unit 12 are attached to the protective cover 46, and are unitized as the light source unit 31. Have been. Further, the first reflection film 40 is entirely formed of the support frame 2.
4 and is held at a predetermined position. Therefore, by attaching the light source unit 31 to the support frame 24, the first and second reflection films 40 and 47 and the cold cathode
, The positional relationship between the backlight unit 12 and the liquid crystal display device having stable optical characteristics can be obtained.

Further, by mounting the relatively small diameter cold cathode tube 32 on the metal protective cover 46 and supporting it, the mechanical strength around the cold cathode tube is improved, and the damage of the cold cathode tube due to impact is reduced. be able to. In particular, according to the above embodiment, the metal cover 46 is formed with the plurality of engagement grooves 48, 50a, 50b extending in the longitudinal direction, so that the mechanical strength can be further improved. it can. Further, the partitioning portion 46e of the protective cover 46 can prevent the light guide 26 from being displaced toward the cold cathode tube 32, thereby preventing the cold cathode tube 32 from being damaged.

When the cold cathode tube 32 is replaced, the entire light source unit 31 can be removed from the support frame 46 by removing the protective cover 46 from the support frame 24, so that the cold cathode tube 32 can be easily replaced. Can be.

Further, since the light source unit 31 has the engaging groove 48 for holding the connection cable 46b at a predetermined position, it is possible to eliminate play of the connection cable and to easily process and route the connection cable. Become. Further, since the connection cable 46b faces the cold cathode tube 32 with the metal protective cover 46 interposed therebetween, the connection cable 46b
And the cold cathode tube can be prevented from leaking. At the same time, the connection cable 46b can be arranged so as to overlap the cold cathode tube 31 in the thickness direction of the backlight unit 12, thereby reducing the outer dimensions of the backlight unit and narrowing the frame of the liquid crystal display device. Becomes possible.

The present invention is not limited to the above-described embodiment, but can be variously modified within the scope of the present invention. For example, the protective cover 4 for the support frame 24
The fixing of 6 is not limited to the combination of the engagement protrusion 42 and the fitting groove 52, and may be performed by screwing.

[0033]

As described above, according to the present invention, the holder, the light source, and the reflection film are attached to the protective cover to form a unit, so that the positional relationship between the light source and the reflection film is always kept constant. The present invention can provide a backlight unit in which stable optical characteristics can be obtained, the light source can be removed from the frame together with the unit, and the light source can be easily replaced, and a liquid crystal display device including the same.

[Brief description of the drawings]

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

FIG. 2 is a perspective view showing a main part of a backlight unit in the liquid crystal display device.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is an exploded perspective view showing a light source unit of the backlight unit.

FIG. 5 is an exploded perspective view showing a support frame of the light source unit and the backlight unit.

FIG. 6 is a sectional view taken along line BB in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Liquid crystal display panel 12 ... Backlight unit 14 ... Holding frame 24 ... Support frame 26 ... Light guide plate 28, 30 ... Optical sheet 31 ... Light source unit 32 ... Cold cathode tube 38 ... Lamp accommodating groove 40 ... 1st reflection film 42 ... Engagement projection 44 Holder 46 Protective cover 48, 50a, 50b Engage groove 52 Fitting groove 54 Holder body 55 Fitting convex part 60a, 60b Connection cable

Claims (7)

[Claims] 1. A frame supporting a light guide plate, a first reflection film fixed to the frame and connected to one end surface of the light guide plate, and one of the light guide plates detachably attached to the frame. A light source unit positioned adjacent to the end face and the first reflective film, wherein the light source unit is attached to the protective cover via a pair of holders and a metal protective cover attached to the frame. A light source facing the first reflection film;
And a second reflection film attached to the protective cover so as to face the light source. 2. The light source is formed in an elongated tube extending along one end surface of the light guide plate, the holder includes a holder body holding both ends of the light source, and a holder extending from the holder body and the protection member. An engaging projection detachably engaged with the cover, wherein the protective cover has an inner surface facing the light source, and the second reflective film is fixed to an inner surface of the protective cover. The backlight unit according to claim 1, wherein: 3. The protection cover has an engagement groove formed on an outer surface thereof and extending between the pair of holders, each of the holders has a connection cable led out from the holder main body, and one of the holder main bodies has a connection cable extending from the holder main body. The derived connection cable is routed to the other holder body side and is positioned by engaging with the engagement groove of the protective cover, and faces the light source with the protective cover therebetween. The backlight unit according to claim 1. 4. The frame has a plurality of engaging projections, the protective cover has a plurality of fitting grooves detachably engaged with the engaging projections, and is detachably attached to the frame. The backlight unit according to any one of claims 1 to 3, wherein the backlight unit is provided. 5. A liquid crystal display panel, comprising: a backlight unit disposed to face the liquid crystal display panel, wherein the backlight unit is fixed to the frame supporting a light guide plate; A first reflection film connected to one end surface of the light guide plate, and a light source unit detachably attached to the frame and positioned adjacent to one end surface of the light guide plate and the first reflection film; The light source unit, a metal protective cover attached to the frame, a light source attached to the protective cover via a pair of holders, facing the first reflective film,
A liquid crystal display device comprising: a second reflective film attached to the protective cover so as to face the light source. 6. The light source is formed in an elongated tube extending along one end face of the light guide plate, the holder includes a holder body holding both ends of the light source, and the holder extends from the holder body. An engaging projection detachably engaged with the cover, wherein the protective cover has an inner surface facing the light source, and the second reflective film is fixed to an inner surface of the protective cover. The liquid crystal display device according to claim 5, wherein: 7. The protection cover has an engagement groove formed on an outer surface thereof and extending between the pair of holders. Each of the holders has a connection cable led out from the holder main body. The derived connection cable is routed to the other holder body side and is positioned by engaging with the engagement groove of the protective cover, and faces the light source with the protective cover therebetween. The liquid crystal display device according to claim 5.