KR20060020222A - Back light assembly and liquid crystal display having the same - Google Patents

Abstract

A backlight assembly capable of improving appearance quality and a liquid crystal display having the same are disclosed. The backlight assembly includes a light source for generating light, a light guide plate for changing the path of light incident from the light source, an optical sheet for controlling light emitted from the light guide plate, and a reflective sheet for reflecting light leaked from the light guide plate. The light guide plate includes a prism pattern on a lower surface thereof, and the prism acid shape of the light guide plate adjacent to the light source is rounded or flat. Accordingly, the appearance quality can be improved by controlling the bright lines generated in the light guide plate incident part.

Description

BACK LIGHT ASSEMBLY AND LIQUID CRYSTAL DISPLAY HAVING THE SAME}

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

FIG. 2 is a diagram schematically illustrating a light induction method using the light guide plate of FIG. 1.

FIG. 3 is an enlarged perspective view of the light guide plate of FIG. 1.

4A and 5A are cross-sectional views of the light guide plate according to the exemplary embodiment of the present invention, taken along the AA ′ line close to the light incident portion and the BB ′ line far from the light incident portion, respectively. FIGS. 4B and 5B are respectively FIGS. 4A and 5B. 5A is an enlarged view of portions A and B, and illustrates a diffusion transmission path of light in the portion.

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

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

120: light guide plate 121: light receiving part

125: prism 126: prism acid

127: prism goal 130: optical sheet                 

140: reflective sheet 200: storage container

800: display unit 900: upper chassis

The present invention relates to a backlight assembly and a liquid crystal display having the same, and more particularly, to a backlight assembly including a light guide plate having a prism pattern and a liquid crystal display having the same.

In general, a 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 display devices, has the advantage of low power consumption and low driving voltage This has been widely used throughout the industry.

A liquid crystal display device includes a thin film transistor (hereinafter referred to as TFT) substrate, a color filter substrate facing the TFT substrate, and a liquid crystal for changing light transmittance according to an applied electric signal interposed between the two substrates. It includes a liquid crystal display panel (liquid crystal display panel) consisting of. In addition, the liquid crystal display device further includes a backlight assembly for supplying additional light since the liquid crystal display panel does not emit light by itself.

The backlight assembly may include a lamp that emits light, a light guide plate for guiding a path of light generated from the lamp toward the liquid crystal display panel, a reflective sheet disposed under the light guide plate to reflect light leaking, and a brightness characteristic of light emitted from the light guide plate. An optical sheet and a storage container for storing them.

Recently, a prism light guide plate has been developed for high luminance and low cost. The prism light guide plate is a light guide plate having a fine pitch prism pattern formed on the bottom thereof, and employing the prism light guide plate has a merit that high luminance can be obtained even when only one anti-prism sheet is used instead of a plurality of prism sheets.

However, the prism light guide plate has a disadvantage in that the light is generated on the light incident part that receives light from the lamp due to the prism pattern formed at the bottom thereof, and thus is weak in appearance quality.

The technical problem to be achieved by the present invention is to provide a backlight assembly that can improve the appearance quality.

Another object of the present invention is to provide a liquid crystal display device having such a backlight assembly.

The backlight assembly for achieving the above technical problem of the present invention includes a light source, a light guide plate, a reflective sheet.

As the light source, various light sources such as a cold cathode fluorescent lamp (CCFL) and a light emitted diode (LED) may be used.

The light guide plate has a light incident part that receives light from the light source and a light exit part that guides the incident light and emits the light. In addition, a prism is formed on one surface of the light guide plate, and the shape of the prism mountain of the prism depends on the distance from the light incident part. The prism acid proximate to the light incident portion side is preferably round or flat. In addition, the direction of the prism is preferably perpendicular to the longitudinal direction of the light source.

The reflective sheet reflects light leaked from the light guide plate to the light guide plate.

If necessary, the backlight assembly may further include a prism sheet for increasing front luminance of light emitted from the light guide plate. The prism direction of the prism sheet is preferably perpendicular to the prism direction formed on the light guide plate.

According to an aspect of the present invention, a liquid crystal display device includes a backlight assembly, a liquid crystal display panel, a storage container, and an upper chassis.

The backlight assembly includes a light guide plate having a light source for generating light, a light incident part that receives light from the light source, and a light exit part that emits light by changing a path of the incident light, and a reflective sheet reflecting light leaked from the light guide plate to the light guide plate. The light guide plate includes a prism formed on one surface of the light guide plate, the prism shape of which varies according to the distance from the light incident portion. The prism acid close to the light incident part is preferably round or flat. In addition, the prism direction is preferably perpendicular to the longitudinal direction of the light source.

The liquid crystal display panel displays an image by using light emitted from the backlight assembly.

The storage container accommodates a backlight assembly and a liquid crystal display panel.                     

The upper chassis fixes the liquid crystal display panel and the backlight assembly to the storage container.

If necessary, the liquid crystal display may further include a prism sheet for increasing front luminance of light emitted from the light guide plate. The prism direction of the prism sheet is preferably perpendicular to the prism direction formed on the light guide plate.

According to the backlight assembly and the liquid crystal display device having the same, the appearance quality may be improved by controlling the bright lines generated at the light guide plate side.

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

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

Referring to FIG. 1, the backlight assembly 100 according to the present invention includes a light generator 110, a light guide plate 120, an optical sheet 130, and a reflective sheet 140.

The light generating unit 110 includes a lamp 112, a lamp cover 114, first and second conductive wires 115 and 116, and a connector 118, and supplies a power supply voltage supplied through the connector 118. The light is emitted by applying the light to the lamp 112 through the first and second conductive wires 115 and 116. Here, the lamp 112 extends long along one side of the light guide plate 120, and one surface of the lamp cover 114 is coated with a reflective material to reflect light emitted from the lamp 112 to the light guide plate 120. As the light source, various light sources such as a cold cathode fluorescent lamp (CCFL) and a light emitted diode (LED) may be used.

The light guide plate 120 is disposed between the optical sheet 130 and the reflective sheet 140, and becomes thinner as it moves away from the lamp 112 to have a wedge-shaped cross section. A plurality of prisms extending in a direction perpendicular to the longitudinal direction of the lamp 112 are formed on a surface (hereinafter referred to as a reflective surface) of the light guide plate 120 that faces the reflective sheet 140, and is supplied from the light generation unit 110. Induced light and light supplied from the reflective sheet 140 are supplied to the optical sheet 130. Here, the prism acid proximate to the lamp 112 is preferably of round or flat shape.

The optical sheet 130 is disposed on the light guide plate 120 to control the brightness of the light guided by the light guide plate 120. Here, the optical sheet 130 is preferably an inverted prism sheet having a prism formed on a surface opposite to the light guide plate, and the prism of the optical sheet 130 extends perpendicular to the longitudinal direction of the light guide plate 120 prism. In this case, the valley defined by the prisms may be a straight line or a curve.

The reflective sheet 140 is disposed under the light guide plate 120 to reflect light leaked through the light guide plate 120 to the light guide plate 120. The reflective sheet 140 may be replaced with a reflective plate.

As such, the backside of the light guide plate 120 employed in the edge type backlight assembly, that is, the reflecting surface, has a plurality of prisms extending perpendicular to the longitudinal direction of the lamp 112, and the prism close to the lamp 112. By rounding or flattening the acid, it is possible to suppress the occurrence of bright lines in the corner portion of the light incident portion of the light guide plate 120.

FIG. 2 is a view for explaining an optical path change by the light guide plate of FIG. 1.

1 and 2, the light from the lamp 112 is incident on the side of the lamp 112 of the light guide plate 120, that is, the incident surface 121, and the incident light is incident on the upper surface of the light guide plate 120. It is emitted through the lower surface, that is, the emitting surface 123 and the reflecting surface 124 or reflected from these surfaces (123, 124). Light emitted through the reflecting surface 124 is reflected by the reflecting plate 140 and re-incident to the light guide plate 120 through the reflecting surface 124.

FIG. 3 is an enlarged perspective view of the light guide plate of FIG. 1, in which a partial region is extracted and removed for convenience of description.

1 and 3, the light guide plate 120 according to the present exemplary embodiment may face a light incident portion (or incident surface) 121 and a reflective sheet 140 and have a bottom portion (or a prism 125 formed thereon). Reflecting surface) 123, and a light emitting portion (or light emitting surface) 124 facing the inverse prism sheet, and receives the light from the lamp 112 through the light incident portion 121, and guides the induced light It exits via the light exit part 124.

The light incident part 121 is a surface closest to the lamp 112 and serves to receive light from the lamp 112.

The bottom portion 123 is formed with a prism 125 pattern defined by the prism mountain 126 and the prism valleys 127, and receives light reflected by the reflective sheet 140. The prism acid 126 of the prism 125 pattern preferably extends perpendicular to the lamp 112 longitudinal direction. In addition, the shape of the prism acid 126 is preferably round or flat at a position close to the light incident part 121.

The light emitter 124 supplies the guided light to the reverse prism sheet 130.

In the drawing, the heights of the prism bones 127 and the heights of the prism mountains 126 of the plurality of prism 125s having the triangular pillar shape are almost the same, and the inclination angles of the two oblique planes forming the prism 125 are the same. Although illustrated, the heights of the prism bones 127 and / or prism mountains 126 of the plurality of prisms 125 may be different, and the inclination angles of the two oblique planes constituting one prism 125 may be different.

In addition, although the prism bone 127 defining the prism 125 is illustrated as being sharp, it may be round otherwise.

In addition, although the direction in which the prism bones 127 defining the prism 125 are formed is perpendicular to the longitudinal direction of the lamp, it may be formed to have a predetermined angle with the longitudinal direction of the lamp.

In addition, although the bone defining the prism 125 is shown to extend in a straight line when viewed from the bottom 123 side, it may be extended or curved while forming a curve.

Next, such a prism will be described in detail with reference to FIGS. 4A to 5.

4A and 5A are cross-sectional views of the light guide plate according to the exemplary embodiment of the present invention, taken along the AA ′ line close to the light incident portion and the BB ′ line far from the light incident portion, respectively. FIGS. 4B and 5B are respectively FIGS. 4A and 5B. 5A is an enlarged view of portions A and B, and illustrates a diffusion transmission path of light in the portion.

As shown in FIG. 4A, the prism acid 126 of the light guide plate 120 prism is rounded near the light incident portion. However, if necessary, the shape of the prism acid 126 may be flat near the light incident portion.                     

As shown in FIG. 5A, the prism mountain 126 has a triangular shape at a distance from the light incident portion.

Referring to FIG. 4B, when the prism mountain 126 is rounded, since the tangent of the prism surface continuously changes along the surface in a certain angle range, even light incident at the same angle is dispersed at various angles according to the incident position. However, in the case of FIG. 5B in which the shape of the prism mountain 126 is a triangle, the tangent of the prism surface has only two angles, so that incident light is dispersed only in two directions. Accordingly, it can be seen that the prism acid 126 having a round shape has a greater degree of dispersion of light than the triangular prism acid 126. This dispersion effect improves the bright line phenomenon in which light and dark bands appear periodically in the vicinity of the light incident part.

6 is an exploded perspective view illustrating a liquid crystal display according to an exemplary embodiment of the present invention. In the present embodiment, since the backlight assembly 100 has substantially the same structure as the backlight assembly 100 described with reference to FIGS. 1 to 5B, the overlapping description is omitted and the same name as in FIGS. 1 to 5B is omitted. And the same reference numerals will be used.

Referring to FIG. 6, the liquid crystal display 1000 according to an exemplary embodiment may include a backlight assembly 100 that supplies light and a display unit that displays an image using light supplied from the backlight assembly 100 ( 800, a storage container accommodating the backlight assembly 100 and the display part 800, and an upper chassis 900 fixing the display part 800 and the backlight assembly 100 to the storage container 100.                     

The display unit 800 includes a liquid crystal display panel 810 for displaying an image, a printed circuit board 820, a data tape carrier package (hereinafter, referred to as TCP) 830, and a gate TCP 840. .

The liquid crystal display panel 810 includes a thin film transistor substrate 812, a color filter substrate 814, and a liquid crystal (not shown) interposed between the two substrates 812 and 814.

The TFT substrate 812 is arranged in a matrix form and includes a pixel electrode made of a transparent conductor and a TFT (not shown), which is a switching element connected thereto, and is made of a transparent glass substrate (not shown). The TFT substrate 812 also includes a data line connected to the source terminal of the TFT to transfer the data voltage and a gate line connected to the gate terminal of the TFT to transfer the scan signal.

The color filter substrate 814 is disposed to face the TFT substrate 812 at regular intervals. The color filter substrate 814 is a substrate on which a plurality of color filters (not shown) are formed by a thin film process to express color by passing only light having a predetermined range of wavelengths. A common electrode (not shown) made of indium tin oxide (ITO) or indium zinc oxide (IZO) is formed on the entire surface of the color filter substrate 814.

In the liquid crystal display panel 810 having such a structure, when a common voltage is applied to the common electrode, a gate-on voltage is applied to the gate terminal of the TFT, and the TFT is turned on and the voltage of the source terminal is applied to the pixel electrode. An electric field is formed between the pixel electrode and the common electrode. The inclination angle of the liquid crystal molecules injected between the TFT substrate 812 and the color filter substrate 814 is determined by this electric field, and the light transmittance is determined according to the determined inclination angle. Therefore, if the voltage applied to the source terminal of the TFT is properly adjusted, the desired image is obtained.

The printed circuit board 820 is connected to one end of the TFT substrate 812 through the data TCP 830. The printed circuit board 820 generates and outputs a data driving signal and a gate driving signal for driving the liquid crystal display panel 810. The data driving signal is a signal for controlling the voltage applied to the data line of the TFT substrate 812, and the driving circuit of the data TCP 830 applies a voltage to the data line in accordance with this signal. The gate driving signal is a signal for controlling the voltage applied to the gate line of the TFT substrate 812. The gate driving signal is applied to the driving circuit of the gate TCP 830 through the data TCP 820, and the gate driving circuit is gated according to the signal. Apply voltage to the line. To this end, a conductive wiring (not shown) for connecting the data TCP 820 and the gate TCP 830 is formed in the TFT substrate 812.

The display unit 800 is mounted on the backlight assembly 100. The liquid crystal display panel 810 is disposed above the storage container 200, and the mounting position is fixed by the guide part 350 formed at four corners of the storage container 200. The printed circuit board 820 is fixed to the back side of the storage container 200 by the bent data TCP 820.

The upper chassis 900 is coupled to the storage container 200 to surround the edge portion of the liquid crystal display panel 810 accommodated in the backlight assembly 1000. The upper chassis 900 prevents the liquid crystal display panel 810 from being separated from the backlight assembly 100 and prevents the fragile liquid crystal display panel 810 from being damaged by an external impact.

Although described above with reference to the embodiments, those skilled in the art can be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below. I can understand.

As described above, according to the present invention, in the backlight assembly having the light guide plate on which the prism pattern is formed, the bright lines generated in the light incident part can be suppressed by rounding or flattening the prism acid adjacent to the light incident part of the light guide plate.

Claims (12)

Glowing light source, A light guide plate having a light incident part that receives light from the light source and a light exit part that changes the path of the incident light; Reflective sheet reflecting light leaked from the light guide plate to the light guide plate Including; The light guide plate includes a prism formed on one surface, and the shape of the prism mountain of the prism varies depending on the distance from the light incident part. Backlight assembly. In claim 1, The prism acid shape is rounded in the shape of the backlight assembly in close proximity to the light incident portion. In claim 2, And the prism extends perpendicular to the longitudinal direction of the light source. In claim 1, And a prism sheet for increasing front luminance of light emitted from the light guide plate. In claim 4, And a prism of the prism sheet extends perpendicular to the prism of the light guide plate. In claim 1, And the prism shape is flat in a position proximate to the light incident portion. A light guide plate including a light source for emitting light, a light incident part that receives light from the light source, and a light exit part that changes the path of the incident light and emits light, and includes a prism on one surface of which a prism mountain shape varies according to a distance from the light incident part. And a reflection sheet reflecting light leaked from the light guide plate to the light guide plate. A liquid crystal display panel displaying an image using light emitted from the backlight assembly; A storage container accommodating the backlight assembly and the liquid crystal display panel; An upper chassis for fixing the backlight assembly and the liquid crystal display panel to the storage container Liquid crystal display comprising a. In claim 7, And the prism acid shape is round in the vicinity of the light incident portion. In claim 8, The prism acid extends perpendicular to the longitudinal direction of the light source. In claim 7, The prism acid shape is flat in the vicinity of the light incident portion. In claim 7, And a prism sheet for increasing the front luminance of the light emitted from the light guide plate. In claim 11, The prism of the prism sheet is perpendicular to the prism of the light guide plate.

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