KR20110041825A - Backlight unit and liquid crystal display device having same - Google Patents

Abstract

The present invention discloses a backlight unit capable of realizing uniform luminance.

The disclosed backlight unit includes a plurality of light emitting diodes, a light guide plate disposed side by side with the plurality of light emitting diodes, and a light compensating part positioned on one side of the light guide plate, wherein the light compensating part is alternated with white and black areas, and the black area is It is characterized by facing a plurality of light emitting diodes.

Description

BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY DEVICE HAVING THE SAME}

The present invention relates to a backlight unit, and more particularly, to a backlight unit capable of realizing uniform brightness and a liquid crystal display device having the same.

In general, liquid crystal displays (LCDs) have tended to be gradually widened due to their light weight, thinness, and low power consumption. In accordance with this trend, liquid crystal displays are used in office automation equipment, audio / video equipment, and the like. The liquid crystal display device displays a desired image on a screen by adjusting a transmission amount according to image signals applied to a plurality of control switches arranged in a matrix form.

Since the liquid crystal display device is not a self-luminous display device, a backlight unit is provided to provide light to the rear surface of the liquid crystal display panel on which an image is displayed.

The backlight unit is classified into an edge type and a direct type according to the form of the light source.

The edge type backlight unit is mainly applied to a medium / small liquid crystal display, and includes a light source on a side thereof, and a light guide plate for guiding light to the entire liquid crystal display panel.

The direct type backlight unit is applied to a large liquid crystal display device of 12 inches or more, and a plurality of light sources are provided on the rear surface of the liquid crystal display panel so that light is directly irradiated directly under the liquid crystal display panel.

Electroluminescent (EL), cold cathode fluorescent lamp (CCFL), hot cathode fluorescent lamp (HCFL), light emitting diode (LED), and the like are used as light sources of the backlight unit.

Among the light sources, light emitting diodes (LEDs) have been widely used in liquid crystal display devices because of their thinness and color reproducibility as well as lower power consumption than lamps using mercury, which is a toxic heavy metal.

The light emitting diode (LED) is a point light source and has a constant emission angle (emission angle) through which light is structurally emitted. Accordingly, in the edge type and the direct type backlight unit in which the light emitting diodes (LEDs) are provided as light sources, luminance differences occur in areas where the light emitting diodes (LEDs) are disposed and areas where the light emitting diodes (LEDs) are not disposed. In other words, the luminance difference means that light and dark portions occur in regions where light emitting diodes (LEDs) are arranged and regions where light emitting diodes (LEDs) are arranged.

Recently, a technique of improving a non-uniform brightness by forming a pattern at an incidence portion of a light guide plate adjacent to a region where a light emitting diode is disposed has been introduced, but it is difficult to form a fine pattern at the incidence portion in the injection process of the light guide plate. There was a problem that was greatly elevated.

Therefore, as described above, in a liquid crystal display device using a light emitting diode (LED) as a light source, a method for improving the luminance imbalance caused by the emission angle (emission angle) of the light emitting diode (LED) while minimizing the cost increase. This is an urgent need.

An object of the present invention is to provide a backlight unit capable of realizing uniform luminance and a liquid crystal display device having the same.

The backlight unit according to an embodiment of the present invention,

A plurality of light emitting diodes; A light guide plate disposed side by side with the plurality of light emitting diodes; And a light compensating part disposed on an upper side of the light guide plate, wherein the light compensating part alternates between white and black areas, and the black areas face the plurality of light emitting diodes.

In addition, the liquid crystal display device of the present invention,

A liquid crystal display panel; A plurality of light emitting diodes for providing light to the liquid crystal display panel; A light guide plate disposed side by side with the plurality of light emitting diodes; And a light compensating part disposed on an upper side of the light guide plate, wherein the light compensating part alternates between white and black areas, and the black areas face the plurality of light emitting diodes.

According to the present invention, white and black tapes are attached or red and black patterns are formed on an upper surface of one side of the light guide plate facing the plurality of light emitting diodes, thereby improving non-uniform luminance generated at an incident part of the light guide plate.

That is, in the present invention, a black tape or a black pattern is attached or formed on one upper surface of the light guide plate corresponding to the region where the plurality of light emitting diodes are disposed to absorb light incident to the region facing the plurality of light emitting diodes, thereby generating a plurality of light emission. The luminance in the region where the diode is disposed is reduced, and the other regions have the advantage that the white tape or the white pattern reflects light so that the luminance of the entire incidence portion of the light guide plate can be made uniform.

In addition, the present invention reduces the manufacturing cost of the liquid crystal display device by making uniform the luminance of the incidence portion of the light guide plate using a white and black tape or a white and black pattern without using an injection process for forming a pattern on the incidence portion of the light guide plate. It has the advantage of minimizing.

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 an edge type liquid crystal display device according to a first exemplary embodiment of the present invention, FIG. 2 is a perspective view illustrating a light guide plate and a light compensating unit of FIG. 1, and FIG. It is a top view which shows the light-guide plate and the light correction part.

As shown in FIGS. 1 to 3, an edge type liquid crystal display device according to an exemplary embodiment of the present invention is disposed on a liquid crystal display panel 110 on which an image is displayed and under the liquid crystal display panel 110. And a backlight unit 120 for providing light.

Although not shown in the drawing, a side surface of the liquid crystal display panel 110 is connected to a gate line of the liquid crystal display panel 110 to supply a scan signal to the gate line, and a data driver connected to the data line. It includes a data driver (not shown) for supplying.

Although not shown, the liquid crystal display panel 110 is a thin film transistor substrate (not shown) on which a thin film transistor (TFT) is formed, and a color filter substrate disposed on the thin film transistor substrate facing the thin film transistor (not shown). ) And a liquid crystal layer (not shown) interposed between the two substrates.

In the thin film transistor substrate, a plurality of gate lines and data lines cross each other to define a pixel, and each thin film transistor includes a thin film transistor.

The color filter substrate has a color filter formed at each pixel, and is formed at an edge of the color filter, and a black matrix is formed at a region corresponding to the gate line, the data line, and the thin film transistor.

The backlight unit 120 that provides light to the liquid crystal display panel 110 includes a bottom cover 180 having an upper surface, a printed circuit board 151 disposed on one side of the bottom cover 180, and the printing. A plurality of light emitting diodes 150 mounted on the circuit board 151, a light guide plate 160 arranged in parallel with the plurality of light emitting diodes 150 to convert point light into surface light, and on the light guide plate 160. Optical sheets 130 arranged to diffuse and collect light, and reflective sheets reflecting light disposed under the light guide plate 160 to travel downward of the light guide plate 160 toward the liquid crystal display panel 110. 170).

The backlight unit 120 further includes a guide unit 153 for guiding light emitted from the light emitting diodes 150 toward the light guide plate 160.

In the exemplary embodiment of the present invention, the structure in which the guide part 153 for guiding the light emitted from the light emitting diode 150 to the light guide plate 160 is limited and described, but is not limited thereto. 170 may be a structure in which the guide part is formed to be bent to surround the printed circuit board 151 and the light emitting diode 150.

The light guide plate 160 is made of a poly methly methacrylate (PMMA) material, and although not shown in detail, the light guide plate 160 may have a wedge shape in which the thickness becomes thinner as the light source unit moves away from the incident surface. A prism pattern may be formed on the rear surface of the light guide plate 160 to refracted incident light toward the optical sheets 130.

The optical sheets 130 include a diffusion sheet for diffusing light, a light collecting sheet for condensing light, and a protective sheet for protecting the light collecting sheet.

The plurality of light emitting diodes 150 may be formed of a plurality of white light emitting diodes emitting white light.

The light emitting diode 150 is not limited to a white (W) light emitting diode, and may be formed of a combination of light emitting diodes emitting red, green, and blue light, respectively, and red (R). , A combination of light emitting diodes emitting green (G), blue (B), and white (W) light, respectively.

One side of the light guide plate 160 facing the light emitting diode 150 is defined as an incidence part 161 through which light emitted from the light emitting diode 150 is incident on the light guide plate 160.

The light compensator is disposed on an upper surface of one side of the light guide plate 160 corresponding to the incident part 161 of the light guide plate 160.

The light compensator includes white and black tapes 201 and 203, and the white and black tapes 201 and 203 are rectangular tapes and are alternately attached to one upper surface of the light guide plate 160.

The white tape 201 reflects light incident from the light emitting diode 150 to the incident part 161 of the light guide plate 160, and the black tape 203 is an incident part of the light guide plate 160 from the light emitting diode 150. It has a function of absorbing light incident on 161.

The first area a1 to which the white tape 201 is attached is defined as an area in which the light emitting diode 150 is not disposed from the incident part 161 of the light guide plate 160.

The second area a2 to which the black tape 203 is attached is defined as an area in which the light emitting diode 150 is disposed from the incident part 161 of the light guide plate 160.

That is, the black tape 203 is disposed on the upper surface of one side of the light guide plate 160 to correspond to the second area a2 of the incident portion 161 of the light guide plate 160 facing the plurality of light emitting diodes 150. .

Here, the number of black tapes 203 is the same as the number of light emitting diodes 150.

In the edge type liquid crystal display according to the first exemplary embodiment of the present invention, a black tape 203 is attached to an upper surface of one side of the light guide plate 160 facing the plurality of light emitting diodes 150, and the other light guide plate 160 is provided. The white tape 201 may be attached to one side of the upper surface to improve non-uniform luminance generated by the incident part 161 of the light guide plate 160.

That is, in the present invention, the black tape 203 is attached to the upper surface of the light guide plate 160 corresponding to the region where the plurality of light emitting diodes 150 are disposed, and the light incident to the region facing the plurality of light emitting diodes 150. Absorbs light and reduces the luminance in the region where the plurality of light emitting diodes 150 are disposed, and in other regions, the white tape 201 reflects the light so that the luminance of the entire incident part 161 of the LGP 160 is uniform. It has the advantage to do it.

In addition, the present invention uses the white and black tapes 201 and 203, and the luminance of the incidence portion 161 of the light guide plate 160 without using an injection process for forming a pattern in the incidence portion 161 of the light guide plate 160. By making it uniform, the manufacturing cost of the liquid crystal display device can be minimized.

4 is a perspective view illustrating a light guide plate and a light compensating unit of a liquid crystal display according to a second exemplary embodiment of the present invention, and FIG. 5 is a plan view illustrating a plurality of light emitting diodes, the light guide plate, and a light compensating unit of FIG. 4.

4 and 5, in the liquid crystal display according to the second exemplary embodiment of the present invention, all configurations except the light compensating unit 300 are identical to those of the liquid crystal display according to the first exemplary embodiment of the present invention. The same reference numerals are used together for the same description and detailed description thereof will be omitted.

The light compensator 300 according to the second exemplary embodiment of the present invention is attached to an upper surface of one side of the light guide plate 160 corresponding to the incident part 161 of the light guide plate 160.

In the light compensator 300, a white region 301 and a black region 303 are alternately disposed, and an adhesive material (not shown) is coated on one surface of the light compensator 300 so as to be attached to an upper surface of the light guide plate 160.

The light compensator 300 is a bar type and is defined as one tape in which the white region 301 and the black region 303 are alternated.

The light emitting diode 150 is not disposed in the incident portion 161 of the light guide plate 160 corresponding to the white region 301, and the light emitting diode is disposed in the incident portion 161 of the light guide plate 160 corresponding to the black region 303. 150 is disposed.

That is, the black region 303 is positioned on one upper surface of the light guide plate 160 facing the plurality of light emitting diodes 150.

Here, the number of black regions 303 is equal to the number of light emitting diodes 150.

In the edge type liquid crystal display according to the second exemplary embodiment of the present invention, light in which the white region 301 and the black region 303 are alternately disposed on an upper surface of one side of the light guide plate 160 facing the plurality of light emitting diodes 150. The correction unit 300 may be attached to improve non-uniform luminance generated by the incident part 161 of the light guide plate 160.

That is, in the present invention, the black region 303 is positioned on the upper surface of one side of the light guide plate 160 corresponding to the region where the plurality of light emitting diodes 150 are disposed, and the light correction unit in which the white region 301 is located in the other region. The light is incident on the black region 303 of the light compensator 300, and the light incident on the other region is absorbed in the white region 301. In this case, the luminance of the entire incident part 1601 of the light guide plate 160 can be made uniform.

In addition, according to the present invention, the luminance of the incident part 161 of the light guide plate 160 is uniformly made using the light compensator 300 without using an injection process for forming a pattern in the incident part 161 of the light guide plate 160. Thus, the manufacturing cost of the liquid crystal display device can be minimized.

6 is a perspective view illustrating a light guide plate and a light compensating unit of a liquid crystal display according to a third exemplary embodiment of the present invention, and FIG. 7 is a plan view illustrating a plurality of light emitting diodes, the light guide plate, and a light compensating unit of FIG. 6.

6 and 7, in the liquid crystal display according to the third exemplary embodiment of the present invention, all components except for the light compensating unit are the same as those of the liquid crystal display according to the first exemplary embodiment of the present invention. In the description, detailed description thereof will be omitted.

The light compensator according to the third exemplary embodiment of the present invention includes a white pattern 401 and a black pattern 403 formed on an upper surface of one side of the light guide plate 160 corresponding to the incident part 161 of the light guide plate 160.

The white and black patterns 401 and 403 are formed on one side upper surface of the light guide plate 160 through a printing process.

The black pattern 403 is formed on an upper surface of one side of the light guide plate 160 facing the plurality of light emitting diodes 150, and the white pattern 403 is formed on the light guide plate not facing the plurality of light emitting diodes 150. 160 is formed on one side of the upper surface.

Here, the number of black patterns 403 is formed equal to the number of light emitting diodes 150.

The black pattern 403 according to the third exemplary embodiment of the present invention absorbs light emitted from the light emitting diodes 150 and is uneven generated at the incidence portion 161 of the light guide plate 160 corresponding to the light emitting diodes 150. Improve brightness.

That is, in the present invention, the black pattern 403 is formed on one surface of the light guide plate 160 corresponding to the region where the plurality of light emitting diodes 150 are disposed, and the white pattern 401 is formed on the other region to form the plurality of light emitting diodes 150. The light incident from the light emitting diodes 150 is absorbed by the black pattern 403, and the light incident to other areas is reflected by the white pattern 401 to uniform the luminance of the entire incident part 161 of the light guide plate 160. Has the advantage of being able to.

In addition, the present invention does not use an injection process for forming a pattern in the incident portion 161 of the light guide plate 160, and uses the white and black patterns 401 and 403 to emit the luminance of the incident portion 161 of the light guide plate 160. By making it uniform, the manufacturing cost of the liquid crystal display device can be minimized.

8 is a perspective view illustrating a light guide plate, an optical sheet, and a light compensating unit of a liquid crystal display according to a fourth exemplary embodiment of the present invention, and FIG. 9 is a view illustrating a plurality of light emitting diodes, the light guide plate, an optical sheet, and a light compensating unit of FIG. 8. One floor plan.

8 and 9, in the liquid crystal display according to the fourth embodiment of the present invention, all configurations except for the light compensator formed on the optical sheet 131 are the liquid crystal display according to the first embodiment of the present invention. The same reference numerals are used in the same configuration, and detailed description thereof will be omitted.

The light compensator according to the fourth exemplary embodiment includes a white pattern 501 and a black pattern 503 formed on one side of the optical sheet 131 disposed on the upper surface of the light guide plate 160.

The white and black patterns 501 and 503 are formed on one lower surface of the optical sheet 130 corresponding to the incident part 161 of the light guide plate 160 through a printing process.

The black pattern 503 is formed on one lower surface of the optical sheet 131 facing the plurality of light emitting diodes 150, and the white pattern 501 is the optical not facing the plurality of light emitting diodes 150. It is formed on one side lower surface of the sheet 31.

Here, the number of black patterns 503 is formed equal to the number of light emitting diodes 150.

The black pattern 503 according to the fourth embodiment of the present invention absorbs the light emitted from the light emitting diodes 150 and is uneven generated at the incidence portion 161 of the light guide plate 160 corresponding to the light emitting diodes 150. Improve brightness.

That is, in the present invention, the black pattern 503 is formed on one lower surface of the optical sheet 131 corresponding to the region where the plurality of light emitting diodes 150 are disposed, and the white pattern 501 is formed on the other region. Light incident from the plurality of light emitting diodes 150 is absorbed by the black pattern 503, and light incident to other regions is reflected by the white pattern 501, thereby causing luminance of the entire incident part 161 of the light guide plate 160. It has the advantage of making it uniform.

In addition, the present invention uses the white and black patterns 501 and 503 formed on the optical sheet 131 without using an injection process for forming a pattern in the incident portion 161 of the light guide plate 160. By uniformizing the luminance of the incident portion 161, the manufacturing cost of the liquid crystal display device can be minimized.

In the fourth exemplary embodiment of the present invention, the structure in which the white and black patterns 501 and 503 are alternately formed on one lower surface of the optical sheet 131 is described, but the present invention is not limited thereto. White and black patterns may be formed on one side of the upper surface.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

1 is an exploded perspective view illustrating an edge type liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a perspective view illustrating the light guide plate and the light compensator of FIG. 1.

3 is a plan view illustrating a plurality of light emitting diodes, a light guide plate, and a light compensating unit.

4 is a perspective view illustrating a light guide plate and a light compensating unit of a liquid crystal display according to a second exemplary embodiment of the present invention.

5 is a plan view illustrating a plurality of light emitting diodes, a light guide plate, and a light compensator of FIG. 4.

6 is a perspective view illustrating a light guide plate and a light compensating unit of a liquid crystal display according to a third exemplary embodiment of the present invention.

7 is a plan view illustrating a plurality of light emitting diodes, a light guide plate, and a light compensating unit of FIG. 6.

8 is a perspective view illustrating a light guide plate, an optical sheet, and a light compensating unit of a liquid crystal display according to a fourth exemplary embodiment of the present invention.

9 is a plan view illustrating a plurality of light emitting diodes, a light guide plate, an optical sheet, and a light compensating part of FIG. 8.

Claims (12)

A plurality of light emitting diodes; A light guide plate disposed side by side with the plurality of light emitting diodes; And And a light compensator disposed on an upper side of the light guide plate. And the light compensating unit alternates between white and black areas, and the black areas face the plurality of light emitting diodes. According to claim 1, And the white and black regions of the light compensating unit each include a plurality of white tapes and a plurality of black tapes. The method of claim 2, And the number of the plurality of tapes is the same as the number of the plurality of light emitting diodes. According to claim 1, And the white and black areas of the light compensator are alternately positioned on one tape. According to claim 1, The white and black regions of the light compensator are formed on the upper side of the light guide plate through a printing process. According to claim 1, The optical sheet is disposed on the light guide plate, and the white and black regions are formed on one side upper or lower surface of the optical sheet. A liquid crystal display panel; A plurality of light emitting diodes for providing light to the liquid crystal display panel; A light guide plate disposed side by side with the plurality of light emitting diodes; And And a light compensator disposed on an upper side of the light guide plate. And the light compensating unit alternates between white and black areas, and the black areas face the plurality of light emitting diodes. 8. The method of claim 7, And the white and black areas of the light compensator are formed of a plurality of white tapes and a plurality of black tapes, respectively. The method of claim 8, Wherein the number of tapes is the same as the number of light emitting diodes. 8. The method of claim 7, And the white and black regions of the light compensator are alternately positioned on one tape. 8. The method of claim 7, And the white and black regions of the light compensator are formed on one side of the light guide plate through a printing process. 8. The method of claim 7, The optical sheet is disposed on the light guide plate, and the white and black regions are formed on one side upper or lower surface of the optical sheet.

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