KR20060078871A - Backlight assembly with a novel diffuser plate and flat panel display device - Google Patents

Abstract

The present invention relates to a backlight assembly having a diffuser plate having a new structure and a flat panel display device having the same. The backlight assembly according to the present invention includes a light source for emitting light and a diffuser plate for diffusing the light emitted therefrom and improving luminance. Here, a plurality of concave portions extending in the longitudinal direction of the light source are formed on one surface of the diffusion plate facing the light source, and a plurality of convex portions are formed on the surface opposite to one surface of the diffusion plate.

Light, diffuser, microlens, brightness, recess, convex, straightness

Description

BACKLIGHT ASSEMBLY HAVING A NEW STRUCTURED DIFFUSING PLATE AND A FLAT DISPLAY DEVICE PROVIDED WITH THE SAME}

1 is an exploded perspective view of a backlight assembly according to an embodiment of the present invention.

2 is a combined perspective view of a backlight assembly according to an embodiment of the present invention.

3 is a partial cross-sectional view taken along line AA of FIG. 2.

4 is an exploded perspective view of a flat panel display device having a backlight assembly according to an exemplary embodiment of the present invention.

The present invention relates to a backlight assembly having a novel diffuser plate and a flat panel display device having the same, and more particularly, to a backlight assembly having a modified structure of a diffuser plate to improve the straightness of light without using an optical sheet. The present invention relates to a flat panel display device having the same.

With the recent rapid development of semiconductor technology, the demand for liquid crystal display devices that are smaller and lighter and has improved performance is exploding.

Recently, liquid crystal displays (LCDs), which have been in the spotlight, have advantages such as miniaturization, light weight, and low power consumption, and as an alternative means to overcome the disadvantages of the conventional cathode ray tube (CRT). It has been attracting attention and is currently used in almost all information processing equipment that requires a display device.

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

Such liquid crystal display devices are gradually employed in large display devices such as TVs. In the case of a large liquid crystal display, a plurality of lamps are used as a light source to display a clearer image, and a diffusion plate is used to evenly diffuse the light emitted from the lamp. Furthermore, in order to improve the brightness of light, many optical sheets, such as a prism sheet, are provided on a diffuser plate.

A diffuser plate having a thickness of about 2 mm to 4 mm serves to scatter light in any direction, and is manufactured to be opaque so that light can be scattered well. As such, when the diffusion plate is manufactured to be opaque, light transmittance is lowered as compared with light scattering well. In addition, since a plurality of optical sheets are used to improve the linearity and brightness of the light, not only the manufacturing cost increases but also the assembly process is complicated. In addition, since a large number of lamps must be installed, a bright line is generated strongly.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and is intended to provide a backlight assembly in which the structure of the diffusion plate is modified to improve the brightness of light.

In addition, the present invention is to provide a flat panel display device having the above-described backlight assembly.

A backlight assembly according to the present invention for achieving the above object includes a light source for emitting light, and a diffusion plate for diffusing the light emitted from it and to improve the brightness. Here, a plurality of concave portions extending in the longitudinal direction of the light source are formed on one surface of the diffusion plate facing the light source, and a plurality of convex portions are formed on the surface opposite to one surface of the diffusion plate.

It is preferable that the opposite surface of the diffuser plate from which light is emitted is exposed to the outside.

The convex portion may be formed in a hemispherical shape.

It is preferable that the diameter of a convex part is 10 micrometers-10 mm.

A plurality of light sources may be arranged side by side spaced apart from each other, and a boundary between a plurality of recesses formed in the diffusion plate may directly face the light source.

The light source can be a lamp.

It is preferable to form the diffusion plate transparently.                     

A flat panel display device according to the present invention includes a flat panel display panel for displaying an image and the aforementioned backlight assembly for supplying light thereto.

Here, the flat panel display panel may directly face the diffusion plate.

The flat panel display panel may be a liquid crystal display panel.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 4. These embodiments of the present invention are merely for illustrating the present invention, but the present invention is not limited thereto.

1 is an exploded perspective view of a backlight assembly 70 according to an embodiment of the present invention, and shows a direct type backlight assembly in which light sources 76 are spaced apart from each other and arranged side by side in the Y-axis direction.

The structure of the backlight assembly 70 shown in FIG. 1 is merely for illustrating the present invention, but the present invention is not limited thereto. Therefore, the present invention can also be applied to backlight assemblies having other structures.

The backlight assembly 70 is formed by combining the diffusion plate 74, the light source 76, the frame mold side 78, and the like. The backlight assembly 70 diffuses the light emitted from the light source 76 to make it uniform and emits the light in the Z-axis direction. The bottom chassis 75 located below the backlight assembly 70 houses internal components including a light source 76, a light source holder (not shown), a frame mold side 78, a reflective sheet 79, and the like. An upper mold frame 71 is fixedly coupled on the bottom chassis 75.                     

Although an lamp is shown as an example of the light source 76 in FIG. 1, this is merely to illustrate the present invention, but the present invention is not limited thereto. Therefore, a light emitting diode (LED) may be used instead of a lamp, or another line light source may be used.

A plurality of light sources 76 that emit light are fixedly installed on the bottom chassis 75, and the reflective sheet 79 is installed on the bottom surface of the bottom chassis 75 to reflect light emitted from the light source 76. . Light emitted from the light source 76 diffuses while passing through the diffusion plate 74.

 When a lamp is used as the light source 76, a cold cathode flourescent lamp (CCFL) or an external electrode flourscent lamp (EEFL), which is a tubular lamp, may be used. A light source holder (not shown) is provided at an end of the light source 76 to fix and support the light source 76. The frame mold side 78 covers and fixes a plurality of lamp holders (not shown).

The back of the bottom chassis 75 is provided with an inverter (73) which is a printed circuit board (PCB) for power supply. The inverter drives the light source 76 by transforming an external power supply to a constant voltage level and applying it to the light source 76. In order to protect the inverter 73 is covered with a shield case (77). A plurality of holes 771 are formed in the shield case 77 to help heat dissipation of the inverter 73.

Light emitted from the plurality of light sources 76 is evenly diffused through the diffusion plate 74 to secure straightness. A plurality of recesses 743 extending in the X-axis direction in the longitudinal direction of the light source 76 are formed on one surface, that is, the lower surface, of the diffuser plate 74 facing the light source 76. These recesses 743 serve to diffuse the light emitted from the light source 76. Since the light is diffused due to the recess 743, the amount of light can be maximized without light loss.

As shown in the enlarged source of FIG. 1, a plurality of convex portions 741 are formed on the opposite surface of one surface of the diffusion plate 74 described above, that is, the upper surface of the diffusion plate 74. . These convex portions 741 may be continuously formed in an embossing form. The convex portions 741 formed as described above serve as a micro lens, and go straight through the light diffused through the concave portion 743 formed at the lower portion of the diffusion plate 74. The convex portions 741 may be formed in front of the upper surface of the diffusion plate 74 or may be formed only in a portion of the upper surface.

In order for the convex portion 741 to act as a micro lens to improve the linearity of light, it is preferable to form the convex portion 741 in a hemispherical shape. In this case, the diameter d of the hemispherical convex portion 741 is preferably 10 µm to 10 mm. The uniformity of the light can be secured through the convex portion 741 having such a size. If the diameter d of the convex portion 741 is less than 10 μm, the lens effect is lowered, and thus, it is difficult to secure the linearity of the light. If the diameter d of the convex portion 741 exceeds 10 mm, the size thereof is It is too large to ensure uniformity of light.

The diffuser plate 74 of this type can be manufactured transparently to improve luminance. Since a plurality of recesses 743 are formed below the diffuser plate 74, the light can be uniformly scattered even if the diffuser plate 74 is not opaquely manufactured.                     

As the material of the diffusion plate 74, PMMA (polymethylmetaacrylate, polymethyl methacrylate), or the like, which is a polymer resin, may be used. The diffusion plate 74 having the structure shown in FIG. 1 can be manufactured by compression and injection molding by heating a chip made of a polymer resin at high temperature. The diffusion plate 74 may also be manufactured by other methods.

FIG. 2 is a perspective view illustrating a backlight assembly 70 according to an embodiment of the present invention, in which all internal components of the backlight assembly 70 illustrated in FIG. 1 are combined.

In the diffuser plate 74 included in the backlight assembly 70 illustrated in FIG. 2, the surface from which light is emitted is exposed to the outside. Thus, even if only the diffusion plate 74 is used without using an optical sheet, the brightness of light can fully be improved. Since a separate optical sheet such as a prism sheet is not required, component cost can be reduced and the manufacturing process can be simplified.

FIG. 3 is a partial cross-sectional view taken along the line AA of FIG. 2, and the light emitted from the light source 76 passes through the diffuser plate 74 to show a phenomenon in which luminance is improved.

As shown in FIG. 3, a plurality of recesses 743 are formed in the lower surface of the diffuser plate 74 opposite the light source 76 to form a boundary 743a. By allowing the light source 76 to directly face the boundary 743a between the recesses 743, the light emitted from the light source 76 is diffused as much as possible. That is, since the boundary 743a between the concave portions 743 is sharply formed, it is impossible to diffuse the light, so that the portion directly faces the light source 76 to maximize the diffusion of the light to minimize the light loss.

The light diffused while passing through the concave portion 743 formed on the lower surface of the diffuser plate 74 passes through a plurality of convex portions 741 formed on the upper surface of the diffuser plate 74 to ensure straightness. The plurality of convex portions 741 formed in the form of a micro lens may straighten the light to suppress the generation of bright lines, thereby supplying uniform light having improved brightness.

4 is an exploded perspective view of a flat panel display device 100 having a backlight assembly 70 according to an exemplary embodiment of the present invention, and the flat panel display device 100 in which the liquid crystal display panel 50 is coupled to the backlight assembly 70. ).

Although the liquid crystal display panel 50 is shown as an example of a flat panel display panel in FIG. 4, this is merely to illustrate the present invention and the present invention is not limited thereto. Accordingly, other types of light receiving flat panel display panels may be used. The flat panel display 100 is manufactured by assembling the backlight assembly 70 while covering the liquid crystal display panel 50 positioned on the backlight assembly 70 with the top chassis 60.

The liquid crystal display panel assembly 40 includes a liquid crystal display panel 50, a COF (chip on film) 43, 44, and a printed circuit board 41, 42, etc. connected thereto to supply a driving signal. It includes. The printed circuit boards 41 and 42 may be accommodated in the side surface of the top chassis 60.

The liquid crystal display panel 50 includes a TFT substrate 51 composed of a plurality of TFTs (thin film transistors), a color filter substrate 53 positioned on the TFT substrate 51, and a liquid crystal (injected therebetween). Not shown). Polarizing plates are attached to the upper portion of the color filter substrate 53 and the lower portion of the TFT substrate 51 to polarize light passing through the liquid crystal display panel 50.

The TFT substrate 51 is a transparent glass substrate on which a matrix thin film transistor is formed, a data line is connected to a source terminal, and a gate line is connected to a gate terminal. In the drain terminal, a pixel electrode made of transparent indium tin oxide (ITO) as a conductive material is formed.

When electrical signals are input from the printed circuit boards 41 and 42 to the gate lines and the data lines of the liquid crystal display panel 50 described above, electrical signals are input to the gate terminal and the source terminal of the TFT, and these electrical signals are input. According to the input of the TFT, the TFT is turned on or turned off so that an electrical signal necessary for pixel formation is output to the drain terminal.

On the other hand, the color filter substrate 53 is disposed thereon opposite the TFT substrate 51. The color filter substrate 53 is a substrate in which RGB pixels, which are color pixels in which a predetermined color is expressed while light passes, are formed by a thin film process, and a common electrode made of ITO is coated on the entire surface thereof. When power is applied to the gate terminal and the source terminal of the TFT and the thin film transistor is turned on, an electric field is formed between the pixel electrode and the common electrode of the color filter substrate. By this electric field, the arrangement angle of the liquid crystal injected between the TFT substrate 51 and the color filter substrate 53 is changed, and the light transmittance is changed according to the changed arrangement angle to obtain a desired pixel.

The printed circuit boards 41 and 42 for receiving image signals from the outside of the liquid crystal display panel 50 and applying driving signals to the gate lines and the data lines, respectively, are respectively attached to the COFs 43 attached to the liquid crystal display panel 50. , 44). In order to drive the flat panel display device 100, the gate side printed circuit board 41 generates a gate driving signal, and the data side printed circuit board 42 generates a data driving signal. A gate driving signal, a data driving signal, and a plurality of driving signals for applying these signals at an appropriate time are generated to generate the gate driving signal and the data driving signal, respectively, on the respective COFs 43 on which the integrated circuit chips 431 and 441 are mounted. , And applied to the gate line and the data line of the liquid crystal display panel 50 through, 44. A control board (not shown) is installed on the back of the backlight assembly 70. The control board is connected to the data side printed circuit board 42 to convert an analog data signal into a digital data signal and then supplies the same to the liquid crystal display panel 50.

The top chassis 60 for preventing the liquid crystal display panel assembly 40 from escaping from the backlight assembly 70 while bending the COFs 43 and 44 to the side of the backlight assembly 70 on the liquid crystal display panel assembly 40. It is provided. Although not shown in FIG. 1, the front case and the rear case are positioned at the top of the top chassis 60 and the bottom of the bottom chassis 75, respectively, to form the flat panel display device 100 by combining them.

In the flat panel display device 100 having such a structure, the diffusion plate 74 directly faces the liquid crystal display panel 50. Accordingly, a large amount of light having improved brightness can be supplied to the liquid crystal display panel 50, so that a clear image can be realized in the liquid crystal display panel 50.

In the backlight assembly according to the present invention, since a plurality of convex portions are formed on the upper surface of the diffusion plate, the linearity of the light may be improved.

In addition, the opposite surface of the diffusion plate from which light is emitted is exposed to the outside, and since there is no need for a separate optical sheet, there is an advantage in that component cost and manufacturing cost are reduced.

Convex portions formed on the diffusion plate may be formed in a hemispherical shape to improve the straightness of the light.

Here, the diameter of the convex portion may be 10 μm to 10 mm to ensure uniformity of light.

Since the boundary between the plurality of recesses formed under the diffuser plate directly faces the light source, it is possible to maximize the diffusion effect of the light using the recesses.

Since a lamp can be used as the light source, there is an advantage of high applicability.

By forming the diffusion plate transparently, it is possible to minimize the loss of light.

Since the flat panel display according to the present invention includes the above-described backlight assembly, it is possible to implement a clear image.

Since the flat panel panel directly faces the diffusion plate, it is possible to supply light with improved brightness.

Since the flat panel display panel can use a liquid crystal display panel, there is an advantage that the application possibility is excellent.

Although the present invention has been described above, it will be readily understood by those skilled in the art that various modifications and variations are possible without departing from the spirit and scope of the claims set out below.

Claims (10)

A light source for emitting light, and Diffusion plate to diffuse the light emitted from the light source and improve the brightness Including, And a plurality of concave portions extending in the longitudinal direction of the light source on one surface of the diffuser plate facing the light source, and a plurality of convex portions formed on a surface opposite to the one surface of the diffuser plate. In claim 1, And a reverse surface of the diffuser plate from which the light is emitted to the outside. In claim 1, The convex portion is a backlight assembly formed in a hemispherical shape. In claim 3, The convex portion has a diameter of 10 μm to 10 mm. In claim 1, A plurality of the light source is arranged side by side spaced apart from each other, the boundary between a plurality of recesses formed in the diffuser plate directly facing the light source. In claim 1, And the light source is a lamp. In claim 1, And a backlight assembly in which the diffusion plate is formed transparently. A flat panel display panel displaying an image, and The backlight assembly of claim 1, wherein the backlight assembly supplies light to the flat panel display panel. Flat display device comprising a. In claim 8, And the flat panel display panel directly faces the diffusion plate. In claim 8, And the flat panel display panel is a liquid crystal display panel.

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