KR20070079259A - Backlight unit and liquid crystal display device including the same - Google Patents

Abstract

A backlight unit and an LCD(Liquid Crystal Display) having the same are provided to improve the uniformity of the brightness by absorbing some of light emitted from a light emitting unit through a light absorbing member. A light emitting unit(12) emits a light. A substrate(14) receives the light emitting unit and supplies external power to the light emitting unit. A reflective layer(16) is disposed on one surface of the substrate where the light emitting unit is received and reflects the emitted light toward the substrate. A light absorbing member absorbs some of the emitted light toward the substrate. The light absorbing member includes a plurality of light absorbing dots formed on the reflective layer. The light absorbing member includes a plurality of light absorbing lines formed on the reflective layer.

Description

BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY DEVICE INCLUDING THE SAME}

1 is an exploded perspective view schematically showing a liquid crystal display according to the present invention.

2 is a side view of FIG. 1.

3 is a view showing the back of the substrate shown in FIG.

4 and 5 are views showing a light absorbing member according to the present invention.

6 to 8 are photographs showing luminance distribution when the light absorbing member according to the present invention is used.

9 to 11 is a view showing a light scattering member according to the present invention.

<Description of Symbols for Main Parts of Drawings>

12 light emitting unit 14 substrate

16 reflection layer 18 optical member

19: adhesive layer 20: backlight unit

60: top chassis 70: display unit

75: liquid crystal display panel

100: liquid crystal display device

The present invention relates to a backlight unit and a liquid crystal display device having the same, and more particularly, to a backlight unit and a liquid crystal display device having the same may improve luminance uniformity.

In general, a liquid crystal display device applies voltage to a specific molecular arrangement of a liquid crystal to convert it into another molecular arrangement, and visually changes optical properties such as birefringence, photoreactivity, dichroism, and light scattering characteristics of the liquid crystal cell emitted by the molecular arrangement. It is a display apparatus which displays information using the modulation of the light by a liquid crystal cell as converting into a change.

The liquid crystal display device includes a liquid crystal display panel for displaying an image and a backlight unit for providing light to the liquid crystal display panel. Since the liquid crystal display panel does not emit light by itself, an image is displayed by using a backlight unit that provides light to the liquid crystal display panel under the liquid crystal display panel.

The backlight unit uses a plurality of fluorescent lamps such as Cold Cathode Fluorescent Lamp (CCFL) or External Electrode Fluorescent Lamp (EEFL) as a light source or a plurality of light emitting devices (LEDs). do.

Since the dual light emitting diode is a semiconductor device, it has a long life and a fast ignition speed, and has been attracting attention as a next-generation light source because it has advantages of low power consumption, strong impact resistance, and suitable for miniaturization and thinning.

However, the light emitting diode has a disadvantage in that light cannot be emitted in all directions of the light emitting diode because the light emitting diode has a limit in the emission angle of the light. In particular, since a local hot spot is formed in the vicinity of the light emitting diode due to the emission angle limit of the light, the overall luminance uniformity is deteriorated.

An object of the present invention is to provide a liquid crystal display device capable of improving the luminance uniformity of the liquid crystal display panel.

According to an embodiment of the present invention, a backlight unit includes a light emitting unit emitting light, a substrate on which the light emitting unit is seated and supplying power to the light emitting unit, and located on one surface of the substrate on which the light emitting unit is seated. A reflective layer for reflecting light emitted toward the substrate, and a light absorbing member for absorbing a portion of the light emitted toward the substrate.

The light absorbing member may be a plurality of light absorbing dots formed on the reflective layer or a plurality of light absorbing lines.

The light absorbing member may be attached to one surface of the reflective layer to fix the substrate at a predetermined position, and may be an adhesive layer made of a translucent material.

According to another embodiment of the present invention, the backlight unit includes a light emitting unit for emitting light, a substrate on which the light emitting unit is seated, and supplying power to the light emitting unit, and located on one surface of the substrate on which the light emitting unit is seated. And a reflective layer that reflects the light emitted towards the substrate, wherein the reflective layer is gray that absorbs a predetermined amount of light.

According to another embodiment of the present invention, the backlight unit is a light emitting unit that emits light, a substrate on which the light emitting unit is seated, and supplies power to the light emitting unit, and is located on one surface of the substrate on which the light emitting unit is seated. A reflective layer for reflecting light emitted toward the substrate, and a light scattering member for scattering the light emitted toward the substrate.

The light scattering member may be a scattering bead coated on the reflective layer.

The light scattering member may be a convex portion or a concave portion formed in the reflective layer.

According to the present invention, a liquid crystal display device includes a light emitting unit emitting light, a substrate on which the light emitting unit is seated and supplying power to the light emitting unit, and a surface of the substrate on which the light emitting unit is seated. And a backlight unit including a reflective layer reflecting light emitted toward the substrate, a light absorbing member absorbing a portion of the light emitted toward the substrate, and a liquid crystal display panel displaying an image using light provided from the backlight unit.

According to another embodiment of the present invention, a liquid crystal display device includes: a light emitting unit emitting light, a substrate on which the light emitting unit is seated and supplying power to the light emitting unit, and a light emitting unit on one surface of the substrate on which the light emitting unit is seated And a backlight unit including a reflective layer reflecting light emitted toward the substrate, a light scattering member scattering light emitted toward the substrate, and a liquid crystal display panel displaying an image using light provided from the backlight unit. do.

Hereinafter, exemplary embodiments of the present invention will be described in more detail with reference to FIGS. 1 to 11. Embodiment of the present invention may be modified in various forms, the scope of the present invention should not be construed as limited to the embodiments described below. This embodiment is provided to explain in detail the present invention to those skilled in the art. Accordingly, the shape of each element shown in the drawings may be exaggerated to emphasize a more clear description.

1 is an exploded perspective view schematically showing a liquid crystal display device 100 according to the present invention.

The liquid crystal display device 100 includes a backlight unit 20 for supplying light, a display unit 70 for receiving images from the backlight unit 20, and displaying an image, and a top chassis 60 for fixing and supporting them. do.

The display unit 70 includes a liquid crystal display panel 75, a driver IC 77, and a flexible printed circuit board (FPCB) 79.

The liquid crystal display panel 75 is injected between the thin film transistor substrate 73 including a plurality of thin film transistors (TFTs), the color filter substrate 71 positioned on the thin film transistor substrate 73, and the substrates. It is made of liquid crystal (not shown). The driving integrated circuit 77 is mounted on the thin film transistor substrate 73 to control the liquid crystal display panel 75.

The flexible circuit board 79 generates a data driving signal, a gate driving signal, a signal for driving the liquid crystal display device 100, and a plurality of timing signals for applying these signals at an appropriate time. The gate driving signal and data The driving signal is applied to the gate line and the data line of the liquid crystal display panel 75, respectively.

A backlight unit 20 is provided below the display unit 70 to provide uniform light to the liquid crystal display panel 75 and is stored on the bottom chassis 28.

One or more light emitting units 12 fixed to the mold frame 22 and supplying light to the display unit 70, a substrate 14 supplying power to the light emitting unit 12, and light emitted from the light emitting unit 12. To guide the light guide plate 16 to the display unit 70, the reflective sheet 26 positioned at the lower front surface of the light guide plate 16 to reflect light, and the luminance characteristics of the light from the light emitting unit 12. An optical sheet 24 for providing to the display unit 70 is provided.

Although not shown in FIG. 1, an inverter board, which is a printed circuit board for power supply, and a printed circuit board for signal conversion are provided on the bottom of the bottom chassis 28. The inverter board transforms an external power supply to a constant voltage level to provide the light emitting unit 12. The printed circuit board for signal conversion is connected to the flexible circuit board 79 to convert analog data signals into digital data signals, thereby converting the liquid crystal display panel. Provided at 75.

A top chassis 60 is provided on the display unit 70 to prevent the display unit 70 from being separated from the bottom chassis 28 while bending the flexible printed circuit board 79 to the outside of the mold frame 22. Although not shown in FIG. 1, a front case and a rear case are positioned at an upper portion of the top chassis 60 and a lower portion of the bottom chassis 28, respectively, to form a liquid crystal display device 100 by combining them.

FIG. 2 is a side view of FIG. 1, and FIG. 3 is a view showing the back of the substrate 14 shown in FIG.

The light emitting unit 12 is mounted on the bottom surface of the substrate 14, and the reflective layer 16, the optical member 18, and the adhesive layer 19 are sequentially coupled to the bottom surface of the substrate 14.

The reflective layer 16 is located on the bottom surface of the substrate 14 and serves to reflect light emitted from the light emitting unit 12 toward the substrate 14. The reflective layer 16 may be located on one side of the substrate 14 on which the light guide plate 16 is located.

The light emitting unit 12 emits light toward the front side. A portion (a) of light is emitted toward the light guide plate 16, another portion (b) is emitted toward the reflective sheet 26, and another portion (c) is emitted toward the substrate 14. The light a emitted toward the light guide plate 16 is provided to the liquid crystal display panel 75 through the light guide plate 16, and the light b emitted toward the reflective sheet 26 is transmitted through the reflective sheet 26. It is reflected and provided to the liquid crystal display panel 75. Light c emitted toward the substrate 14 is reflected through the reflective layer 16 and provided to the liquid crystal display panel 75.

In general, the reflective layer 16 is white to reflect incident light and is formed by applying a dye to the bottom surface of the substrate 14.

As described above, the light c emitted toward the substrate 14 is reflected through the reflective layer 16 to be provided to the liquid crystal display panel 75, and the provided light is emitted from the light emitting unit in which the light emitting unit 12 is located. 12 is concentrated on one side (light incidence part) of the liquid crystal display panel 75. Thus, there is a local hot spot in the incidencer. Local hot spots degrade the luminance uniformity of the entire liquid crystal display panel 75. Therefore, in order to prevent this, some of the light c emitted toward the substrate 14 is reflected by the reflective layer 16, and a part of the light c is absorbed by the reflective layer 16. You can adjust the brightness.

Therefore, the reflective layer 16 may be gray having both the property of reflecting light of white and the property of absorbing light of black. The luminance uniformity of the liquid crystal display panel 75 may be improved by adjusting the brightness of the reflective layer 16.

The optical member 18 is positioned on one surface of the reflective layer 16, and absorbs or scatters a part of the light emitted from the light emitting unit 12 toward the substrate 14 to improve the uniformity of luminance of the liquid crystal display panel 75. Play a role. This is to prevent a local roster from occurring on one side of the liquid crystal display panel 75 as described above. Therefore, when the brightness uniformity of the liquid crystal display panel 75 is improved by adjusting the brightness of the reflective layer 16, the separate optical member 18 may not be used. The optical member 18 may be located on one side of the substrate 14 on which the light guide plate 16 is located.

The optical members 18 may be classified into light absorbing members 18a and 18b and light scattering members 18c, 18d and 18e according to their functions. This will be described later.

The adhesive layer 19 is positioned on one surface of the optical member 18, and serves to fix the substrate 14 on the mold frame 22. In general, the adhesive layer 19 is made of a transparent material to transmit incident light. However, the adhesive layer 19 may be made of a translucent material to absorb or scatter some of the light c emitted through the substrate 14 or the light reflected through the reflective layer 16. This is to prevent a local roster from occurring on one side of the liquid crystal display panel 75 as described above.

The adhesive layer 19 may be located on one side of the substrate 14 on which the mold frame 22 is located.

The luminance uniformity of the liquid crystal display panel 75 may be improved by adjusting the transparency of the adhesive layer 19. When the luminance uniformity of the liquid crystal display panel 75 is improved by controlling the transparency of the adhesive layer 19, a separate The optical member 18 may not be used.

4 and 5 are views showing the light absorbing members (18a, 18b) according to the present invention.

The light absorbing members 18a and 18b absorb the incident light. Since black has a property of absorbing light, it is possible to form black dots or black lines on the reflective layer 16 by using the same.

4 is a view illustrating a plurality of light absorption dots 18a formed on the reflective layer 16. The size or number of the light absorption dots 18a may be adjusted in a direction to improve luminance uniformity of the liquid crystal display panel 75.

FIG. 5 is a view illustrating a plurality of light absorption lines 18b formed on the reflective layer 16. Similarly, the thickness or the number of the light absorption lines 18b may be adjusted in a direction to improve the luminance uniformity of the liquid crystal display panel 75.

FIG. 6 shows the luminance distribution when the light absorbing members 18a and 18b are not used, and FIG. 7 is a photograph showing the luminance distribution when the light absorbing dots 18a are used. 8 is a photograph showing luminance distribution in the case of using a light absorbing member having a black color as a whole.

The luminance distribution with respect to the luminance distribution shown in FIGS. 6 to 8 may be represented as shown in Table 1.

6 7 8 Average brightness 1499 1476 1396 % Of traditional method 100.0 98.5 93.1 Center luminance 1464 1461 1387 % Of traditional method 100.0 99.8 94.7 Highest brightness 2276 1697 1605 Average luminance contrast (%) 151.8 115.0 115.0

Referring to Table 1, when the light absorption dot 18a is used (FIG. 7), the average brightness is decreased by 1.5%, and the average brightness ratio (%) of the highest brightness is 115.0%, which is 36.8% decrease compared to FIG. have. This indicates that the luminance uniformity can be greatly improved in the state where the average luminance is not significantly lowered.

However, when the light absorbing member having a black color as a whole is used (FIG. 8), the average luminance contrast (%) of the highest luminance is 115.0%, which is the same as that of FIG. 7, but the average luminance is decreased by 6.9%. This improves the luminance uniformity, but it can be seen that the average luminance is greatly reduced.

Referring to Table 1, in order to improve the brightness uniformity, the light absorption dot 18a may be formed on the reflective layer 16, and the number or size of the light absorption dots 18a may be changed in consideration of the average brightness and the brightness uniformity. You can see that it can be adjusted.

In addition, it can be seen that the light absorbing member having a black color is not preferable because the average brightness is greatly reduced, and as described above, the brightness and brightness uniformity can be satisfied by adjusting the brightness.

As described above, the light absorbing member may be provided by the reflective layer 16 or the adhesive layer 19. That is, by adjusting the brightness of the reflective layer 16 or the transparency of the adhesive layer 19, a portion of the light c emitted toward the substrate 14 may be absorbed.

9 to 11 show light scattering members 18c, 18d, and 18e according to the present invention.

The light scattering members 18c, 18d, and 18e scatter incident light, and the scattered light is extinguished through diffuse reflection. Diffuse reflection refers to reflections in which light collides with a rough incident surface and scatters in all directions. It occurs when a rough surface is roughly equal to or rougher than the wavelength of a wave.

Unlike the light absorbing members 18a and 18b described above, the light scattering members 18c, 18d, and 18e absorb the part of the light c emitted toward the substrate 14 to improve luminance uniformity. It is intended to improve the luminance uniformity by dissipating a part of the light c emitted toward the top.

9 is a view showing the convex portion 18c formed on the reflective layer 16, and FIG. 10 is a view showing the concave portion 18d formed on the reflective layer 16. As shown in FIG.

As described above, part of the light that has collided with the convex portion 18c and the concave portion 18d is scattered to cause diffuse reflection, and the light causing the diffuse reflection disappears.

The convex portion 18c and the concave portion 18d may be provided by forming the convex portion 18c and the concave portion 18d formed on the substrate 14 and applying the reflective layer 16 on the substrate 14, It may be provided by forming the convex portion 18c and the concave portion 18d directly on the reflective layer 16.

As described above, the convex portion 18c and the concave portion 18d may have various sizes and numbers in order to improve luminance uniformity of the liquid crystal display panel 75.

In addition, although only one of the convex portion 18c or the concave portion 18d is formed in FIGS. 9 and 10, the convex portion 18c and the concave portion 18d may be formed together.

FIG. 11 is a diagram showing scattering beads 18e applied on the reflective layer 10.

In the method of applying the scattering beads 18e, the small bead shaped scattering beads 18e are mixed with the raw material of the reflecting layer 16 when the reflecting layer 16 is applied onto the substrate 14, and then onto the substrate 14. Apply to The applied raw material forms the reflective layer 16, and the scattering beads 18e are applied together with the reflective layer 16 and fixed on the reflective layer 16.

The scattering beads 18e serve to scatter the incident light in the same way as the convex portions 18c and the concave portions 18d. Similarly, the scattering beads 18e may have various sizes and numbers in order to improve luminance uniformity of the liquid crystal display panel 75.

As described above, the luminance of the liquid crystal display panel 75 is absorbed by absorbing a part of the light c emitted toward the substrate 14 through the light absorbing members 18a and 18b or the light scattering members 18c, 18d, and 18e. Uniformity can be improved.

According to the present invention, the luminance uniformity of the liquid crystal display panel can be improved.

Claims (10)

A light emitting unit for emitting light; A substrate on which the light emitting unit is mounted and which supplies power from the outside to the light emitting unit; A reflection layer positioned on one surface of the substrate on which the light emitting unit is mounted and reflecting light emitted toward the substrate; And And a light absorbing member absorbing a part of the light emitted toward the substrate. The method of claim 1, And the light absorbing member is a plurality of light absorbing dots formed on the reflective layer. The method of claim 1, And the light absorbing member is a plurality of light absorbing lines formed on the reflective layer. The method of claim 1, The light absorbing member is attached to one surface of the reflective layer to fix the substrate in a predetermined position, the backlight unit, characterized in that the adhesive layer made of a translucent material. A light emitting unit for emitting light; A substrate on which the light emitting unit is mounted and which supplies power from the outside to the light emitting unit; And Located on one surface of the substrate on which the light emitting unit is seated, and includes a reflective layer reflecting the light emitted toward the substrate, And the reflective layer is gray to absorb some of the light emitted toward the substrate. A light emitting unit for emitting light; A substrate on which the light emitting unit is mounted and which supplies power from the outside to the light emitting unit; A reflection layer positioned on one surface of the substrate on which the light emitting unit is mounted and reflecting light emitted toward the substrate; And And a light scattering member for scattering light emitted toward the substrate. The method of claim 6, The light scattering member is a backlight unit, characterized in that the scattering beads (bead) applied on the reflective layer. The method of claim 6, The light scattering member is a backlight unit, characterized in that the irregularities formed in the reflective layer. A light emitting unit emitting light, a substrate on which the light emitting unit is seated and supplying power to the light emitting unit, a reflective layer positioned on one surface of the substrate on which the light emitting unit is seated, and reflecting light emitted toward the substrate, the substrate A backlight unit including a light absorbing member absorbing a part of the light emitted toward the light emitting unit; And And a liquid crystal display panel which displays an image using light provided from the backlight unit. A light emitting unit emitting light, a substrate on which the light emitting unit is seated and supplying power to the light emitting unit, a reflective layer positioned on one surface of the substrate on which the light emitting unit is seated, and reflecting light emitted toward the substrate, the substrate A backlight unit including a light scattering member for scattering light emitted toward the light source; And And a liquid crystal display panel which displays an image using light provided from the backlight unit.

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