KR20140112739A - Light Guide Plate And Backlight Unit Using The Same - Google Patents

Abstract

The present invention, in order to achieve the object, provides a light guide plate which comprises a a first plane and a second plane and is formed in a first height. The light guide plate comprises: a first side surface and a second side surface divided from the side surface of the light guide plate; a third side surface which faces the side surface, is connected to the first side surface and second side surface, and has a smaller second height than the first height; and a locking tab which is connected to the first side surface, the second side surface, the third side surface, and the side surface thereof and comprises a first surface and a second surface connected to the first plane or the second plane.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a light guide plate and a backlight unit using the same,

The present invention relates to a light guide plate and a backlight unit using the same, and relates to a backlight unit for supplying a light source to a display device and a light guide plate included therein.

2. Description of the Related Art A liquid crystal display device is a device that displays an image while light supplied from a light source provided inside the liquid crystal display device passes through a liquid crystal panel. Here, the light source that supplies light to the liquid crystal panel is used in all liquid crystal display devices except for the reflection type liquid crystal display device which reflects external light, and since most of the light source supplies light from one side of the liquid crystal panel, It is called a back light unit. When the distribution of the light sources supplied by the backlight unit is uneven, the image forming capability is degraded. To prevent this, the backlight unit further includes an optical sheet for supplying a uniform light source.

1 is an exploded perspective view of a part of a liquid crystal display module including a backlight unit.

The backlight unit includes a light source element 10 for supplying light to the liquid crystal. At this time, the light source device 10 uses a low temperature fluorescent lamp or a light emitting diode (LED) device. Here, the light source element 10 is an LED element in which a light frame 11 is additionally provided. A light guide plate 6 for converting the light source output from the light source device 10 into a surface light source and a diffusion plate 7 for uniformly distributing light, ). Thereafter, first and second condenser plates 8 and 9 are formed to improve the brightness of light passing through the diffusion plate 7, and a protective film (not shown) can be additionally formed thereon have. The light source element 10 is fixed by the mold frame 2 and the light frame 11. [ At this time, the mold frame 2 may further include a reflector 4 for efficiency of light output from the light source device 10.

In the backlight unit 1 described above, since the light guide plate 6 formed by a structure of changing the linear light source into the surface light source in the light source element 10 has a characteristic of being expanded by heat, A liquid crystal display module in which a backlight unit 1 having a clearance in the mold frame 2 and the light guide plate 6 is applied has a problem that the light source supply becomes unstable due to the flow of the light guide plate 6 .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a light guide plate and a backlight unit using the same, which minimize the problems caused by the flow and thermal expansion of the light guide plate located inside the backlight unit.

In order to achieve the above object, the present invention provides a light guide plate having a first plane and a second plane and formed at a first height, the first and second side surfaces being branched from the side surface of the light guide plate, A third side connected to the first and second sides and having a second height less than the first height and a third side connected to the first and second and third sides and the side, And a fixing tab having a first surface and a second surface that are continuous with the second plane.

The first and second side surfaces and the third side surface are connected to each other, and each of the first, second and third side surfaces is formed as a flat surface or a curved surface.

Further, at least one of the first and second surfaces is rounded.

When one of the first and second surfaces is rounded, the other surface is flat.

The second height is 130 탆 or more.

According to another aspect of the present invention, there is provided a light guide plate comprising: a light guide plate having a first plane and a second plane and formed at a first height; A third side facing the side surface and connected to the first and second side surfaces and having a second height smaller than the first height; 1 and second and third side surfaces, and a first surface and a second surface connected to the side surface and continuing with the first or second surface; A light source element for supplying light to the light guide plate; And a mold frame having the light guide plate, the mold tab having a tab insertion portion formed in a hole shape to cut the fixing tab to be fixed, or the like.

The light guide plate has protrusions formed on the first plane or the second plane.

The light guide plate further includes a plurality of optical members positioned on the light guide plate and seated on the mold frame.

The first and second side surfaces and the third side surface are connected to each other, and each of the first, second and third side surfaces is formed as a flat surface or a curved surface.

At least one of the first and second surfaces is rounded.

Further, when either one of the first surface or the second surface is rounded, the other surface is flat.

The second height is 130 탆 or more.

The light guide plate and the backlight unit using the light guide plate according to the present invention have an effect that a light guide plate is fixed to the mold frame to supply a more stable light source.

1 is an exploded perspective view of a part of a liquid crystal display module including a backlight unit.
2 is an exploded perspective view of a part of a liquid crystal display module including a light guide plate and a backlight unit using the same, according to a first embodiment of the present invention.
3A and 3B are views showing a light guide plate and a fixing tab according to the first embodiment.
4A and 4B are views showing a light guide plate having a fixing tab according to the second embodiment.
5A and 5B are views showing a fixing tab and a light guide plate according to a comparative example.
6A and 6B show the reliability test results of the fixed tap according to the thermal cycle and the temperature change.

Specific details for carrying out the present invention will be described in detail below with reference to the drawings.

2 is an exploded perspective view of a part of a liquid crystal display module including a light guide plate and a backlight unit using the same, according to a first embodiment of the present invention.

2, the backlight unit 101 according to the first embodiment of the present invention includes a reflection plate 104, a fixing tab 105, and a reflecting plate 104 on a mold frame 102 having a tab inserting portion 103, And the light source device 110 and the light frame 111. The light guide plate 106 is formed by the light guide plate 106, the diffusion plate 107, the first and second light condensing plates 108 and 109, At this time, the reflector 104 may be omitted depending on the shape and the material of the mold frame 102, and the diffuser plate 107 and the first and second condenser plates 108 and 109 may uniformly distribute light to the entire light guide plate 106 , And other optical materials having the function of uniformly focusing the dispersed light. Also, the light source device 110 applied to the backlight unit according to the present invention is an LED (Light Emitting Diode) device.

The fixing tab 105 is formed on the side surface of the light guide plate 106 and is positioned in the tab insertion portion 103 formed in the mold frame 102 to prevent the light guide plate 106 from flowing. At this time, the fixing tabs 105 formed on the light guide plate 106 may be formed asymmetrically with respect to each other on the side surface of the light guide plate 106 in order to increase the flow prevention efficiency. The fixing tab 105 shown in the figure is an example of a shape extended from the light guide plate 106. The number and size of the fixing tabs 105 may vary depending on the shape applied to the backlight unit 101. [

Here, when the light guide plate 106 receives heat by the light source device 110, its volume increases. In this case, when there is no clearance between the tab inserting portion 103 formed on the mold frame 102 and the fixing tab 105, the light guide plate 106, which is heated by the light source device 110, ), And a frictional sound is generated. In order to prevent this, the light guide plate 106 is made of a colorless transparent material having a low coefficient of friction such as polymethyl methacrylate (PMMA) or polyethyleneterephthalate (PET) and high light transmittance . In addition, the fixing tabs 105 branched from the light guide plate 106 may be formed so as to have a clearance therebetween when the tabs are inserted into the tab insertion portion 103.

In the first embodiment, the fixing tab 105 is formed by branching a part of the side surface of the light guide plate 106, and the thickness of the end of the fixing tab 105 and the thickness of the light guide plate 106 are different from each other. This will be described in detail with reference to FIGS. 3A and 3B.

3A and 3B are views showing a light guide plate and a fixing tab according to the first embodiment.

3A, the light guide plate 106 according to the first embodiment of the present invention and the fixing tab 105 formed on the side surface thereof include a first side surface 131, a second side surface 132, A third side 133 facing the side 128 of the light guide plate 106 formed by the first height 141 and formed with the second height 142 and a third side 133 formed by the first curved surface 151 and the second curved surface 152, The fixing tabs 105 formed on the side surfaces 128 of the light guide plate 106 are formed. Here, the second height 142 is preferably 130 탆 or more.

The first side surface 131 and the second side surface 132 that are branched from the third side surface 133 formed at the first height 141 and the side surface 128 of the light guide plate 106 are formed with respect to the third side surface 133 Or may be formed to have a larger angle outside the third side 133. At this time, the first to third side surfaces 131, 132, and 133 may be curved surfaces to reduce the influence of light reflected from the fixing tabs 105.

The first curved surface 151 formed along the circumference of the first to third side surfaces 131, 132 and 133 and the side surface 128 of the light guide plate 106 is disposed between one corner of the third side surface 133 and the light guide plate 106, And a second curved surface 152 formed along the circumference of the side surfaces 128 of the light guide plate 106 and the first to third side surfaces 131, 132 and 133, And is connected to the other side of the side surface 133 and the second plane 122 of the light guide plate 106. In this case, the first and second curved surfaces 151 and 152 may be formed in a planar shape when they are connected to the first and second planes 121 and 122. Also, as shown in FIG. 3B, The first to third side surfaces 131 to 133 of the fixing tabs 105 extending from the first side surface 106 may be connected to each other. This is because the light transmitted from the light guide plate 106 is reflected by the first to third side surfaces 131 to 133 of the fixing tab 105 formed in a flat shape when each surface of the fixing tab 105 is flat A difference in luminance occurs in the form of a line or a point. Accordingly, it is a structure to prevent the reflected light from being concentrated in one place, or to collect the light into the fixing tabs 105 to uniformly distribute the luminance of the finally outputted light.

The fixing tab 105 according to the first embodiment is difficult to apply when the first height 141 of the light guide plate 106 is less than 230 탆. 4A and 4B illustrate a light guide plate and a fixing tab according to a second embodiment of the present invention.

4A and 4B are views showing a light guide plate having a fixing tab according to the second embodiment.

As shown in FIG. 4A, the fixing tab 205 according to the second embodiment is a structure that can be applied when the thickness of the light guide plate 206 is extremely thin and the rounding process can not be performed on both sides. A third side surface 233 formed by the second side surface 232 and a side surface 228 of the light guide plate 206 formed by the first height 241 and formed with the second height 242, And has a curved surface 251 and a curved surface 252, and extends from the side surface 228 of the light guide plate 206. Here, the second height 242 is preferably 130 탆 or more.

The first side surface 231 and the second side surface 232 that are branched from the third side surface 233 formed by the first height 241 and the side surface 228 of the light guide plate 206 are formed on the third side surface 233 Or may be formed outside the third side 233 by 90 degrees or more. At this time, the first and second side surfaces 231 and 232 may be curved surfaces.

The plane 252 formed along the circumference of the side surfaces 228 of the first to third side surfaces 231, 232 and 233 and the light guide plate 206 is parallel to the third plane 233 and the first plane 234 of the light guide plate 206 And the curved surface 251 formed along the periphery of the side surfaces 228 of the first and second side surfaces 231 and 232 and the light guide plate 206 is connected to the third side surface 233 and the light guide plate 206, To a second plane (222) The planar surface 252 and the curved surface 251 of the fixing tab 205 may be formed in a planar shape when they are connected to the first and second planes 251 and 252 of the light guide plate 206.

In addition, the plane 252 of the fixing tab 205 may be spaced apart from the first plane 221 on the side surface 228 of the light guide plate without parallel lines.

4B, the first side surface 231 to the third side surface 233 of the fixing tab 205 extending from the light guide plate 206 may be connected to one surface. When the respective surfaces of the fixing tabs 205 are flat, the light transmitted from the light guide plate 206 is reflected by the first to third side surfaces 231 to 233 of the fixing tab 205, , Or a dot-like shape. Accordingly, it is a structure to prevent the reflected light from being concentrated in one place, or to collect the light into the fixing tabs 105 to uniformly distribute the luminance of the finally outputted light.

In order to form the fixing tab 105 having the curved surface 251 and the flat surface 152 as described above, it is preferable that the second height 142 is formed to be 130 탆 or more.

The reason why the fixing tabs are formed as illustrated in the first and second embodiments is to increase the thermal expansion and the strength of the fixing tabs, and the effect of this will be described in detail with comparative examples having different shapes.

5A and 5B are views showing a fixing tab and a light guide plate according to a comparative example.

5A, the fixing tab 35 is extended from the light guide plate 36, and the thickness of the fixing tab 35 and the light guide plate 36 is the same. In this case, the light guide plate 36 expands due to heat so that the light guide plate 36 receives a force in the direction of the arrow shown in the figure. Since the repulsive force generated in the light guide plate 36 and the mold frame 32 by the thermal expansion is lower than the stresses of the light guide plate 36 and the fixing tab 35, the light guide plate 36 and the fixing tabs 35 35). At this time, when the repulsive force transferred from each of the light guide plate 36 and the fixing tab 35 to be transmitted is greater than the stress of the light guide plate 36, the light guide plate 36 is guided in the direction of line A or line A ' Cracks will occur. Such cracks prevent the light guide plate 36 from changing the front light source into the surface light source, and the backlight unit in which such a phenomenon occurs can not transmit normal light. This is caused by the fact that the repulsive force generated between the fixing tab 35 and the light guide plate 36 can not be dispersed between them and the mold frame 32, and a comparative example in which the structure is taken into consideration is shown in FIG.

As shown in Fig. 5B, in order to prevent the light guide plate (36 in Fig. 5A) from being damaged by the repulsive force generated in the mold frame (32 in Fig. 5A) And a fixing tab 39 is formed. In this case, the fixing tab 39 is formed to have two pairs of surfaces facing each other on the side surface of the light guide plate 37 and one surface parallel to the side surface of the light guide plate 37. At this time, the fixing tab 39 has a lower stress than the fixing tab 35 (FIG. 5A) having the same thickness as the light guide plate 36 (FIG. 5A). However, the fixing tab 39 formed with such a structure has a stress not to be broken by the repulsive force and has an effect of reducing the repulsive force generated due to the thermal expansion due to the structure smaller than the side surface area of the light guide plate 37 . Accordingly, the force transmitted from the fixing tab 39 is also reduced, and the repulsive force, which is concentrated on the interface between the fixing tab 39 and the light guide plate 37, is reduced by about 33% The light guide plate 37 can be prevented from being damaged.

As described above, the light guide plate 37 according to the comparative example is a structure that can reduce the repulsive force to prevent damage when thermal expansion occurs. However, since the stress of the fixing tab 39 is low, a force due to an external impact is transmitted to the completed module or apparatus, or the damage due to the force applied during the process of inserting the light guide plate 37 into the mold frame (not shown) Can occur. To this problem, a pressure was vertically applied to the fixing tabs (105 and 39 in Fig. 3A) formed on the light guide plate 106 (Fig. 3A) and the light guide plate 37 according to the first embodiment, Table 1 and Table 2 showing the results of the respective stiffness measurements are compared in detail.

Comparative Example Result (Unit: kgf) Twist leaving out Some damage Number of occurrences 7 38 5 Lowest pressure value 0.06 0.10 0.20 Highest pressure value 0.48 0.76 0.42 Occurrence average pressure value 0.21 0.27 0.28

Results of the first embodiment (unit: kgf) Twist leaving out Some damage Number of occurrences 14 22 14 Lowest occurrence pressure value 0.25 0.43 0.24 Peak generation pressure value 0.97 0.96 1.77 Average pressure value 0.61 0.66 0.75

As shown in Table 1, in the case of the fixing tab (39 in FIG. 5B) according to the comparative example, the numerical value of the bending indicating that the shape is deformed, and the numerical value of the partial breakage which is connected to the light guide plate, Is smaller than the numerical value of the experimental result of the fixing tab (105 of FIG. 3A) according to the first embodiment of the present invention, and is high with respect to the dropout. However, in the case of the fixing tab (105 in FIG. 3A) according to the first embodiment of the present invention, the average value of the stresses against bending increased by 0.4 kgf and the average value of the stresses Is increased by 0.47 kgf.

Also, in the case of the dropout completely falling off the light guide plate, the average value of the stress was increased by 0.39 kgf as compared with the fixing tab 39 according to the comparative example. According to these results, the fixing tab 39 according to the first embodiment of the present invention, (105 in FIG. 3A) is increased by about 0.4 kgf.

Such an increase in stress exhibits a more stable effect even in the process of inserting the light guide plate into the mold frame and the process of transferring the force due to the external impact. Especially, when the light guide plate is actually applied, 6b will be described in detail.

6A and 6B show the reliability test results of the fixed tap according to the thermal cycle and the temperature change.

As shown in FIG. 6A, the heat cycle to be applied to the light guide plate is repeated 200 times under the condition that the conversion cycle is changed every 23 minutes in the temperature range of 85 DEG C and -40 DEG C, in order to proceed the reliability check. It is set above the temperature range used in everyday life and it is to see if it can maintain its normal shape under extreme conditions.

6A, the fixing tab according to the first embodiment of the present invention and the light guide plate using the same, as shown in FIG. 6B showing the shape of the light guide plate in FIG. 6A, However, in the case of the fixed tap according to the comparative example and the light guide plate using the same, there were 10 defects in total, including detachment and breakage in the reliability test.

Therefore, the light guide plate having the fixing tabs according to the first embodiment of the present invention and the backlight apparatus using the same can have higher reliability.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made without departing from the spirit of the present invention.

105: fixing tab 106: light guide plate
121, 122: first and second planes 128: side
131: first side 132: second side
133: third side 141: first height
142: second height

Claims (12)

A light guide plate having a first plane and a second plane and formed at a first height,
A third side facing the side surface and connected to the first and second side surfaces and having a second height smaller than the first height; 1 and second and third sides and a securing tab having a first side and a second side connected to the side and continuing with the first or second side,
.
The method according to claim 1,
Wherein the first and second side surfaces and the third side surface are connected to each other, and each of the first, second and third side surfaces is formed as a flat surface or a curved surface.
The method according to claim 1,
Wherein at least one of the first surface and the second surface is rounded.
The method of claim 3,
Wherein when one of the first and second surfaces is rounded, the other surface is flat.
The method according to claim 1,
And the second height is 130 占 퐉 or more.
A light guide plate having a first plane and a second plane and formed at a first height;
A third side facing the side surface and connected to the first and second side surfaces and having a second height smaller than the first height; 1 and second and third side surfaces, and a first surface and a second surface connected to the side surface and continuing with the first or second surface;
A light source element for supplying light to the light guide plate;
The light guide plate is mounted on the mold frame. The mold tab is cut to fix the fixing tab,
.
The method according to claim 6,
Wherein the light guide plate has protrusions formed on the first plane or the second plane.
The method according to claim 6,
And a plurality of optical members positioned on the light guide plate and seated on the mold frame.
The method according to claim 6,
Wherein the first and second side surfaces and the third side surface are connected to each other, and each of the first, second and third side surfaces is formed as a flat surface or a curved surface.
The method according to claim 6,
Wherein at least one of the first surface and the second surface is rounded.
11. The method of claim 10,
Wherein when one of the first surface and the second surface is rounded, the other surface is planar.
The method according to claim 6,
And the second height is 130 占 퐉 or more.

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