KR20060094681A - Back light assembly and liquid crystal display apparatus having the same - Google Patents

Abstract

Disclosed are a backlight assembly and a liquid crystal display having the same, which can reduce manufacturing costs. The backlight assembly includes a lamp and a light guide plate for generating light. The light guide plate extends from one side of the incidence part to which the light generated from the lamp is incident, a reflection part formed with the first prism patterns having a polygonal shape, and extends from the other side of the incidence part to face the reflection part and to form the second prism patterns. Include an exit section. The light guide plate contains a diffusing agent therein. Therefore, even if the optical sheet such as the prism sheet is removed, the same level of brightness as in the past can be obtained, and manufacturing cost can be reduced.

Description

BACK LIGHT ASSEMBLY AND LIQUID CRYSTAL DISPLAY APPARATUS HAVING THE SAME}

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

FIG. 2 is a perspective view illustrating a rear surface of the light guide plate shown in FIG. 1.

FIG. 3 is an enlarged view of a portion A of FIG. 2.

4 is a perspective view showing another embodiment of the first prism pattern.

FIG. 5 is an enlarged partial view of a portion of the light guide plate illustrated in FIG. 1.

6 is a perspective view showing another embodiment of a second prism pattern.

7 is an exploded perspective view illustrating a liquid crystal display according to an exemplary embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

100: backlight assembly 200: lamp

300: light guide plate 310: incident part

320: reflection unit 330: exit unit

340: first prism pattern 342: first prism

350: second prism pattern 352: second prism

410: reflective sheet 420: optical sheet

422: diffusion sheet 424: reflective polarizing film

500: liquid crystal display 600: display unit

610: liquid crystal display panel 620: driving circuit

The present invention relates to a backlight assembly and a liquid crystal display device having the same, and more particularly, to a backlight assembly and a liquid crystal display device having the same, which can improve brightness and reduce manufacturing costs.

In general, the liquid crystal display (Liquid Crystal Display) is a flat panel display device that displays an image using a liquid crystal (Liquid Crystal), is thinner and lighter than other flat panel display devices, and has a low driving voltage and low power consumption It has advantages and is used extensively throughout the industry.

The liquid crystal display device includes a liquid crystal display panel including a thin film transistor (hereinafter, referred to as TFT) substrate, a color filter substrate facing the TFT substrate, and a liquid crystal layer interposed between the two substrates to change light transmittance. Liquid Crystal Display Panel). In addition, since the liquid crystal display device is a non-light emitting device that does not emit light by itself, the liquid crystal display panel for displaying an image requires a backlight assembly for supplying light to the liquid crystal display panel.

The conventional backlight assembly includes a lamp for generating light and a light guide plate for guiding a path of light generated from a lamp disposed on a side of the lamp in a liquid crystal display panel direction. In addition, the backlight assembly further includes optical sheets such as a diffusion sheet, two prism sheets, and a reflective polarizing film disposed on an exit surface of the light guide plate in order to improve the brightness uniformity and front brightness of the light.

Therefore, the conventional backlight assembly has a manufacturing cost is increased by using a large number of optical sheets, the brightness is reduced due to the light loss through the optical sheets.

Accordingly, the present invention has been made in view of such a problem, and the present invention provides a backlight assembly capable of reducing manufacturing costs and increasing luminance by removing optical sheets.

In addition, the present invention provides a liquid crystal display device having the above-described backlight assembly.

The backlight assembly according to an aspect of the present invention described above includes a lamp and a light guide plate for generating light. The light guide plate may include an incident part to which light generated from the lamp is incident, a reflecting part extending from one side of the incident part and having first polygonal prism patterns formed thereon, and extending from the other side of the incident part to face the reflecting part. It includes an exit portion formed with two prism patterns. The light guide plate contains a diffusion agent therein.

According to an aspect of the present invention, a liquid crystal display device includes a backlight assembly and a liquid crystal display panel. The backlight assembly includes a lamp and a light guide plate for generating light. The light guide plate may include an incident part to which light generated from the lamp is incident, a reflecting part extending from one side of the incident part and having first polygonal prism patterns formed thereon, and extending from the other side of the incident part to face the reflecting part. It includes an exit portion formed with two prism patterns. The light guide plate contains a diffusing agent therein. The liquid crystal display panel displays an image using light supplied from the backlight assembly.

According to the backlight assembly and the liquid crystal display having the same, the prism sheets may be removed by forming prism patterns in the reflecting portion and the emitting portion of the light guide plate and adding a diffusion agent therein. Therefore, the manufacturing cost can be reduced while having the same brightness characteristic as before.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is an exploded perspective view illustrating a backlight assembly according to an exemplary embodiment of the present invention, and FIG. 2 is a perspective view illustrating a rear surface of the light guide plate illustrated in FIG. 1.

1 and 2, the backlight assembly 100 according to an embodiment of the present invention includes a lamp 200 and a light guide plate 300.

At least one lamp 200 is disposed at both sides of the light guide plate 300 facing each other. The lamp 200 generates light in response to a driving voltage applied from an external inverter (not shown). The lamp 200 is, for example, made of a cold Cathode Fluorescent Lamp (CCFL) having an elongated cylindrical shape. Meanwhile, the lamp 200 may be disposed only on one side of the light guide plate 300.

The light guide plate 300 changes the traveling path of the light incident from the lamp 200 and emits the light in a specific direction. The light guide plate 300 extends from an incident part 310 to which light generated from the lamp 200 is incident, a reflecting part 320 extending from one side of the incident part 310, and the other side of the incident part 310. The emission unit 330 facing the reflector 320 is included.

First prism patterns 340 having a polygonal shape are formed in the reflective part 320 of the light guide plate 300. In the present embodiment, the first prism patterns 340 have a rectangular shape. The light incident through the incident part 310 is changed by the first prism patterns 340 and is emitted through the exit part 330. The first prism patterns 340 have the same size and are formed at a uniform density on the reflector 320. On the contrary, the first prism pattern 340 may be formed on the reflector 320 with non-uniform density and have different sizes so as to adjust the amount of reflected light according to the position. For example, the first prism pattern 340 is formed to increase in size and density in order to increase the amount of reflected light as it moves away from the incident part 310 to which light is incident.

A second prism pattern 350 is formed in the exit part 330 of the light guide plate 300 to focus the traveling direction of the emitted light in the front direction. The second prism pattern 350 is formed over the entire surface of the exit portion 330. The second prism pattern 350 is formed of second prisms 352 that are in contact with each other, and the second prisms 352 are formed in a direction parallel to the incident part 310.

The light guide plate 300 is made of a transparent material for transmitting light. For example, the light guide plate 300 is made of polymethyl methacrylate (PMMA). The light guide plate 300 includes a diffusing agent (not shown) contained therein for diffusing light. The light guide plate 300 has a haze of about 3% to about 5% by the addition of the diffusion agent, and has a light transmittance of about 85% to about 90%. The haze and the light transmittance of the light guide plate 300 are controlled through the added diffusion agent. The diffusing agent is composed of spherical small particles to increase the diffusion rate, and has a size of less than about 10 mu m. The diffusing agent is made of a diffusing material such as titanium oxide (TiO 2) or silicon oxide, for example.

Meanwhile, the backlight assembly 100 further includes a reflective sheet 410 disposed below the reflector 320 and at least one optical sheet 420 disposed above the emitter 330.

The reflective sheet 410 reflects light leaking to the outside through the reflecting unit 320 of the light guide plate 300 and enters the light into the light guide plate 300 again. The reflective sheet 410 is made of a material having high light reflectance. For example, the reflective sheet 410 is made of polyethylene terephthalate (PET) or polycarbonate (PC).

The optical sheet 420 improves the luminance characteristic of the backlight assembly 100 by changing the path of the light emitted through the light emitter 330. The optical sheet 420 includes a diffusion sheet 422 disposed on the emission unit 330 and a reflective polarization film 424 disposed on the diffusion sheet 422. The diffusion sheet 420 diffuses the light emitted through the emission unit 330, thereby improving the brightness uniformity of the light. The reflective polarizing film 424 increases the brightness of light by recycling light in a manner of transmitting P waves and reflecting S waves among incident light. The backlight assembly 100 may add or remove various kinds of optical sheets according to desired luminance characteristics.

FIG. 3 is an enlarged view of a portion A of FIG. 2.

Referring to FIG. 3, the first prism pattern 340 formed in the reflector 320 of the light guide plate 300 has a rectangular shape in plan view. The first prism pattern 340 is composed of first prisms 342 connected to each other. The first prisms 342 extend in an oblique direction with respect to the incident part 310. The first prisms 342 have a triangular cross section showing a plane perpendicular to the longitudinal direction. For example, the pitch PW1 of the first prism 342 is about 50 μm, and the height PH1 of the first prism 342 is about 25 μm. In addition, the vertex angle θ1 of the first prism 342 has a range of about 85 ° to about 88 °.

4 is a perspective view showing another embodiment of the first prism pattern.

Referring to FIG. 4, the first prism pattern 344 according to another embodiment has a hexagonal shape in plan. The first prism pattern 344 is composed of first prisms 346 connected to each other. The first prisms 346 extend in an oblique direction with respect to the incident part 310. The first prisms 346 have a triangular cross section showing a plane perpendicular to the longitudinal direction. Since the specific example of the first prism 346 is the same as that shown in FIG. 3, overlapping description will be omitted.

FIG. 5 is an enlarged partial view of a portion of the light guide plate illustrated in FIG. 1.

Referring to FIG. 5, a second prism pattern 350 is formed in the emission part 330 of the light guide plate 300. The second prism pattern 350 is composed of second prisms 352 that are in contact with each other. The second prisms 352 are formed to have a direction parallel to the incident part 310 in the longitudinal direction.

In the present embodiment, the second prism 352 has a convex lens-shaped cross section showing a surface perpendicular to the longitudinal direction in order to change the path of the emitted light in the front direction and to secure some apparent luminance uniformity. Has For example, the pitch PW2 of the second prism 352 is about 100 μm, and the height PH2 of the second prism 352 is about 50 μm. In addition, the circumference of the second prism 352 has a range of about 35 μm to about 45 μm.

6 is a perspective view showing another embodiment of a second prism pattern.

Referring to FIG. 6, the second prism pattern 354 according to another embodiment may include second prisms 356 connected to each other. The second prisms 356 are formed to have a direction parallel to the incident part 310 in the longitudinal direction.

In this embodiment, the second prism 356 has a substantially triangular cross section showing a plane perpendicular to the longitudinal direction, and has a rounded top shape. For example, the pitch PW3 of the second prism 356 is about 100 μm, and the overall height PH3 of the second prism 356 is about 50 μm. At this time, the rounded height PH4 of the second prism 356 is about 15 μm. Also, the vertex angle θ2 of the second prism 356 is about 90 degrees.

7 is an exploded perspective view illustrating a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 7, the liquid crystal display 500 according to the exemplary embodiment of the present invention includes a backlight assembly 100 and a display unit 600.

The backlight assembly 100 may have any one of various embodiments shown in FIGS. 1 to 6. Therefore, detailed description thereof will be omitted.

The display unit 600 includes a liquid crystal display panel 610 for displaying an image using light supplied from the backlight assembly 100, and a driving circuit unit 620 for driving the liquid crystal display panel 610.

The liquid crystal display panel 610 includes a first substrate 612, a second substrate 614 coupled to the first substrate 612, and a liquid crystal interposed between the first substrate 612 and the second substrate 614. Layer (not shown).

The first substrate 612 is a substrate in which thin film transistors (hereinafter referred to as TFTs), which are switching elements, are formed in a matrix form. For example, the first substrate 612 is made of glass. A data line and a gate line are respectively connected to the source terminal and the gate terminal of the TFTs, and a pixel electrode made of a transparent conductive material is connected to the drain terminal.

The second substrate 614 is a substrate in which RGB pixels for realizing color are formed in a thin film form. For example, the second substrate 614 is made of glass. The common electrode made of a transparent conductive material is formed on the second substrate 614.

In the liquid crystal display panel 610 having such a configuration, when power is applied to the gate terminal of the TFT and the TFT is turned on, an electric field is formed between the pixel electrode and the common electrode. By the electric field, the arrangement of liquid crystal molecules of the liquid crystal layer disposed between the first substrate 612 and the second substrate 614 is changed, and the transmittance of light supplied from the backlight assembly 100 is changed according to the arrangement change of the liquid crystal molecules. The image is changed to display an image of a desired gradation.

The driving circuit 620 may include a data printed circuit board 622 for supplying a data driving signal to the liquid crystal display panel 610, a gate printed circuit board 624 for supplying a gate driving signal to the liquid crystal display panel 610, and data printing. A data driving circuit film 626 connecting the circuit board 622 to the liquid crystal display panel 610 and a gate driving circuit film 628 connecting the gate printed circuit board 624 to the liquid crystal display panel 610. . The data driving circuit film 626 and the gate driving circuit film 628 are made of, for example, a tape carrier package (TCP) or a chip on film (COF). Meanwhile, the gate printed circuit board 624 may be removed by forming separate signal wires on the liquid crystal display panel 610 and the gate driving circuit film 628.

According to such a backlight assembly and a liquid crystal display having the same, first prism patterns having a polygonal shape are formed in the reflective part of the light guide plate, second prism patterns are formed in the exit part, and a diffusion agent is added therein. Therefore, even if the optical sheet such as the prism sheet is removed, the same level of brightness as in the past can be obtained, and manufacturing cost can be reduced.

In the detailed description of the present invention described above with reference to the preferred embodiments of the present invention, those skilled in the art or those skilled in the art having ordinary skill in the art will be described in the claims to be described later It will be understood that various modifications and variations can be made in the present invention without departing from the scope of the present invention.

Claims (14)

A lamp for generating light; And An incident part to which light generated from the lamp is incident, a reflecting part extending from one side of the incidence part, and having a polygonal first prism pattern formed thereon, and a second prism pattern extending from the other side of the incident part and facing the reflecting part; And a light guide plate including a formed emission part and a diffusing agent therein. The backlight assembly of claim 1, wherein the first prism pattern has a shape of one of a rectangle and a hexagon. The backlight assembly of claim 2, wherein the first prism pattern includes first prisms that are in contact with each other, and the first prisms have a triangular shape in cross section. The backlight assembly of claim 1, wherein the second prism pattern comprises second prisms that are in contact with each other, and the second prisms are formed in a direction parallel to the incident part. 5. The backlight assembly of claim 4, wherein the second prism has a convex lens shape in cross section. 6. The backlight assembly of claim 5, wherein the second prism has a substantially triangular cross section and is rounded at an upper end thereof. The backlight assembly of claim 1, wherein the diffusion agent is made of titanium oxide (TiO 2) or silicon oxide (SiO 2). The backlight assembly of claim 1, wherein the light guide plate has a haze of 3% to 5%. The backlight assembly of claim 8, wherein the light guide plate has a light transmittance of about 85% to about 90%. The method of claim 1, A reflective sheet disposed below the reflective portion; A diffusion sheet disposed above the emission unit; And And a reflective polarizing film disposed on the diffusion sheet. A lamp for generating light, and An incident part to which light generated from the lamp is incident, a reflecting part extending from one side of the incidence part, and having a polygonal first prism pattern formed thereon, and a second prism pattern extending from the other side of the incident part and facing the reflecting part; A backlight assembly including a light emitting plate including a light emitting plate formed therein and a diffusion agent therein; And And a liquid crystal display panel for displaying an image using light supplied from the backlight assembly. The liquid crystal display of claim 11, wherein the first prism pattern has one of a rectangle and a hexagon, and has first prisms having a triangular cross section. 12. The method of claim 11, wherein the second prism pattern is made of a second prism in contact with each other, the second prism is characterized in that the cross-sectional shape of any one of a convex lens shape or a rounded upper triangle shape. Liquid crystal display device. The liquid crystal display of claim 11, wherein the light guide plate has a haze of 3% to 5% and a light transmittance of 85% to 90%.

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