KR20080069010A - Backligth and display device having the same - Google Patents

Abstract

A backlight unit and a display device comprising the same are provided to increase the amount of light supplied to the center area of a light-guiding plate, thereby enhancing the brightness of the backlight unit by improving the arrangement of LED(Light Emitting Diode) elements disposed at one side of the light-guiding plate. A backlight unit comprises a plurality of LED elements(200) and a light-guiding plate(100). Each of the LED elements includes at least one light-emitting chip. At least one surface of the light-guiding plate is disposed adjacently to the plurality of LED elements. The LED elements are denser in the center area of the side face of the light-guiding plate than in both edge regions of the side face of the light-guiding plate.

Description

BACKLIGTH AND DISPLAY DEVICE HAVING THE SAME}

1 is a conceptual diagram of a backlight according to an embodiment of the present invention.

2 is a conceptual diagram of a backlight according to a modification of the embodiment;

3 is an exploded perspective view schematically illustrating a backlight according to an embodiment.

4 is an exploded perspective view schematically illustrating a backlight according to a modification of the embodiment;

5 is an exploded perspective view of a display device including the backlight assembly according to an exemplary embodiment.

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

100: light guide plate 200: LED unit

210: substrate 220: flexible printed circuit board

300: storage member 400: optical sheet

500: upper substrate 600: lower substrate

1000: display panel 2000: backlight

The present invention relates to a backlight and a display device including the same. The present invention relates to a backlight and a display device including the same to improve the brightness of an edge type backlight using a plurality of LEDs as a light source.

A liquid crystal display (LCD), which is one of flat panel displays, is a device that displays a target image by changing a liquid crystal array of unit pixels to adjust a light transmittance. Since the liquid crystal display device does not emit light by itself, the liquid crystal display device includes a backlight disposed under the liquid crystal display panel to provide light to the liquid crystal display panel.

Recently, as a light source of a backlight, an LED unit having advantages of long life, low power consumption, light weight, and thickness is used. In particular, an edge type backlight in which a plurality of LED units are arranged in one row on one side of the light guide plate is used for thinning and thinning. That is, the light emitted from the LED unit in the form of a point light source is changed into a surface light source in the light guide plate to irradiate light over the entire area of the plate-shaped liquid crystal display panel.

The user's vision feels brighter at high luminance at the center than at uniform light emitted from the front of the liquid crystal display panel. Therefore, it is efficient to raise the luminance level in the center portion within a range that satisfies the uniformity of the appropriate level. In the related art, the center luminance of the backlight is improved by using an optical system such as a light guide plate and an optical sheet. To this end, a separate pattern was designed on the lower surface of the light guide plate, or a reflective sheet was attached to allow light from the edge of the light guide plate to re-inject into the light guide plate. However, the light reaching the side of the light guide plate suffers a light loss at the interface of the optical system (the light guide plate and the reflective sheet), and in particular, a problem arises in the form of light leakage while causing lambertial scattering reflection in the reflective sheet. This causes a significant amount of light generated by the LED unit to be lost and disappeared without contributing to the increase in luminance.

Therefore, the present invention is derived to solve the above problems, while changing the arrangement of the LED unit disposed on the side of the light guide plate, narrowing the distance between the LED unit in the center region of the light guide plate, the LED unit toward the edge region It is an object of the present invention to provide a backlight and a display device including the same, which can improve luminance by increasing the amount of light supplied to the center region of the light guide plate by widening the interval therebetween.

A density of LED units including a plurality of LED units including at least one light emitting chip according to the present invention, and a light guide plate having at least one side adjacent to the plurality of LED units, and disposed in a central region of one side of the light guide plate. Provides a backlight that is denser than both edge regions on one side.

The spacing between the plurality of LED units is preferably increased gradually toward both edges at the center of one side of the light guide plate. The spacing between the LED units is effectively mirror symmetrical with respect to the center of the one side.

Preferably, the maximum spacing between the LED units in the center region of one side of the light guide plate is smaller than the minimum spacing in both edge regions of the one side. It is effective that the spacing between the LED units in the center region is the same, and the spacing between the LED units in the both edge regions is the same.

The plurality of LED units are preferably mounted on a substrate or flexible printed circuit board.

The plurality of LED units preferably include a red light emitting chip, a green light emitting chip, and a blue light emitting chip, or a white light emitting chip that emits white light.

In addition, a plurality of LED units including at least one light emitting chip for emitting light according to the present invention and a light guide plate having at least one side disposed adjacent to the plurality of LED units, disposed in the central region of one side of the light guide plate Provided is a display device including a backlight having a denser density of the LED unit than both edge regions of one side and a display panel displaying an image using light supplied from the backlight.

The backlight may further include a reflecting plate provided below the light guide plate, an optical sheet provided above the light guide plate, and a housing member accommodating the plurality of LED units and the light guide plate.

The spacing between the plurality of LED units is effectively increased gradually toward both edges from the center of one side of the light guide plate.

It is effective that the maximum spacing between the LED units in the center region of one side of the light guide plate is smaller than the minimum spacing between both edge regions of the one side.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention in more detail. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the embodiments are intended to complete the disclosure of the present invention, and to those skilled in the art to fully understand the scope of the invention. It is provided to inform you.

1 is a conceptual diagram of a backlight according to an embodiment of the present invention, Figure 2 is a conceptual diagram of a backlight according to a modification of one embodiment.

3 is an exploded perspective view schematically illustrating a backlight according to an exemplary embodiment, and FIG. 4 is an exploded perspective view schematically illustrating a backlight according to a modified example of the exemplary embodiment.

1 to 4, the backlight according to the present exemplary embodiment includes a light guide plate 100 and a plurality of LED units 200 disposed adjacent to one side of the light guide plate 100.

The spacing between the plurality of LED units 200 gradually increases from the center of one side of the light guide plate 100 toward both edges. Through this, the amount of light supplied to the central region of the light guide plate 100 may be increased to improve the luminance of the central region of the backlight. As a result, the luminance of the display panel felt by the user may be increased. The center of one side of the light guide plate 100 refers to a point that bisects the length of one side of the light guide plate 100.

As illustrated in FIG. 1, the light guide plate 100 has a substantially rectangular shape, and the plurality of LED units 200 are disposed in one long side area of the light guide plate 100 having a rectangular shape. The LED units 200 are preferably arranged on a single line line (one line). However, the present invention is not limited thereto, and the LED units 200 may be arranged on a plurality of parallel lines depending on the thickness and length of one side of the light guide plate 100 and the brightness of the LED unit 200.

In the present embodiment, as shown in FIG. 1, 15 LED units 200 are disposed adjacent to one side of the light guide plate 100. The eighth LED unit is located in an area corresponding to the center of the light guide plate 100, the first to seventh LED units are disposed on the left side of the eighth LED unit, and the ninth to fifteen LED units are on the right side of the eighth LED unit Is placed on. LED units disposed on the left and right sides are preferably mirror-symmetric with respect to the center. This will be described below the separation interval between the LED unit based on the LED unit disposed in the left region.

Among the separation intervals L1, L2, L3, L4, L5, L6, L7 of each of the first to eighth LED units, the separation interval L1 between the first LED unit and the second LED unit is the longest, and the seventh It is preferable that the spacing L7 between the LED unit and the eighth LED unit is the shortest. That is, the separation interval L1 between the first LED unit and the second LED unit is longer than the separation interval L2 between the second LED unit and the third LED unit. The separation interval L2 between the second LED unit and the third LED unit is longer than the separation interval L3 between the third LED unit and the fourth LED unit. The spacing L3 between the third LED unit and the fourth LED unit is longer than the spacing L4 between the fourth LED unit and the fifth LED unit. The separation interval L4 between the fourth LED unit and the fifth LED unit is longer than the separation interval L5 between the fifth LED unit and the sixth LED unit. The spacing L5 between the fifth LED unit and the sixth LED unit is longer than the spacing L6 between the sixth LED unit and the seventh LED unit. The spacing L6 between the sixth LED unit and the seventh LED unit is longer than the spacing L7 between the seventh and eighth LED units.

Here, the number of the LED units 200 is not limited to 15, but may be more or less than this.

In the prior art, a plurality of LED units are arranged on one side of the light guide plate at uniform intervals, so that the amount of light irradiated to the central area and the peripheral area of the light guide plate is uniform, or the separation interval between the LED units in the peripheral area of the light guide plate is equal to the center area. In comparison, the light quantity irradiated to the peripheral region was made larger than the light quantity irradiated to the central region. However, through this, the luminance in the center of the light guide plate is lowered, thereby lowering the luminance of the entire display device, and problems due to light loss in the edge region occur. However, in this embodiment, as the distance from the center region of the light guide plate 100 to both edge regions is gradually widened, the amount of light irradiated to the center region is greater than the amount of light irradiated to the peripheral region. The luminance in the central region of the light guide plate 100 may be improved, and the light loss in the edge region may be reduced.

As such, the density of the LED units 200 in the central region of one side of the light guide plate 100 is relatively dense compared to the peripheral region so that the number of LED units 200 positioned in the central region of one side of the light guide plate 100 may be determined. The luminance in the central region of the light guide plate 100 can be improved. That is, when the plurality of LED units 200 irradiates a uniform amount of light, the amount of light supplied to the central region of one side of the light guide plate 100 may be increased. As described above, as another modification for increasing the density of the LED unit 200 in the center region compared to the peripheral region of one side of the light guide plate 100, the LED unit 200 in the center region of one side of the light guide plate 100. The maximum spacing D1 between them is smaller than the minimum spacing D2 between the LED units 200 in both edge regions of one side of the light guide plate 100. In this case, as shown in FIG. 2, the spacing between the LED units 200 in the center area is the same, and the spacing between the LED units 200 in the peripheral area is preferably the same. Of course, the present invention is not limited thereto, and the separation intervals between the LED units 200 in the center area may be different from each other, and the separation intervals between the LED units 200 in the peripheral area may be different from each other.

The density refers to the number of LED units 200 disposed in a predetermined area, and the density of the central area is higher or dense than the peripheral area. The number of LED units 200 disposed in the same area of the central area and the peripheral area. Means that there is more center area than the surrounding area. In addition, the lengths E1 and E2 of both edge regions of one side of the light guide plate 100 are preferably lengths corresponding to 10 to 40% of the total length K of one side of the light guide plate 100, respectively. The length C of the central region of one side is preferably a length region corresponding to 20 to 80% of the total length K of one side of the light guide plate 100.

As shown in FIG. 3, the plurality of LED units 200 according to the present exemplary embodiment are mounted on the rod-shaped substrate 210. The substrate 210 is provided in one side area of the light guide plate 100. In this case, the substrate 210 has a length and a thickness corresponding to the length and thickness of one side of the light guide plate 100. The spacing between the plurality of LED units 200 mounted on the substrate 210 gradually increases from the center of the substrate 210 toward both edge regions (length directions). The substrate 210 uses a metal core printed circuit board (MCPCB) substrate on which an electrode pattern (not shown) is formed. Through this, the heat emitted by the LED units 200 may be quickly emitted to the outside. PCB may be used as the substrate 210. Although not shown, it is effective in this embodiment that a white insulating film is coated on the upper surface (the surface on which the LED unit 200 is mounted) of the substrate 210. Of course, the present invention is not limited thereto, and a light reflection film may be formed on the upper surface of the substrate 210. In addition, although not shown in the drawings, a fixing member including a fixing groove or a fixing protrusion for fixing the substrate 210 may be provided at one side of the substrate 210.

The plurality of LED units 200 are mounted on the center line in the longitudinal direction of the substrate 210. At this time, the plurality of LED units 200 is preferably connected in series and / or parallel. Each of the plurality of LED units 200 emits white light. To this end, the LED unit 200 includes a red light emitting chip emitting red light, a green light emitting chip emitting green light, and a blue light emitting chip emitting blue light. In the present embodiment, one red and blue light emitting chip is provided in the unit LED unit 200, and two green light emitting chips are provided. The LED unit 200 emits white light by mixing red light, green light and blue light. Of course, the present invention is not limited thereto, and the LED unit 200 may include at least one white light emitting chip that emits white light. Although not illustrated, the LED unit 200 may further include a power supply terminal for applying power to the light emitting chips and a molding part encapsulating the light emitting chips.

A substrate 210 having a plurality of LED units 200 having the above-described structure disposed at a high density in a central area is provided in an area adjacent to one side of the light guide plate 100. Of course, the substrate 210 may be disposed in close contact with the light guide plate 100.

The light guide plate 100 changes the light having the optical distribution in the form of a point light source of the LED unit 200 mounted on the substrate 210 to the light having the optical distribution in the form of a surface light source. As the light guide plate 100, it is generally preferable to use PMMA (Polymethylmethacrylate) having high strength and not easily deforming or breaking. An optical pattern, such as a prism pattern, may be formed on the upper surface and the lower surface of the light guide plate 100 through which light is emitted.

Of course, the present embodiment is not limited thereto, and a plurality of LED units 200 may be mounted on the flexible printed circuit board 220 as in the modification of FIG. 4. In addition, the light guide plate 100 and the flexible printed circuit board 220 may include an accommodating member 300 for accommodating the LED unit 200.

The flexible printed circuit board 220 includes a mounting portion in which the LED unit 200 is mounted, and an extension portion extending from the mounting portion. The extension part is connected to an external power source to apply power to the LED units 200 mounted on the mounting part. The mounting portion is manufactured in the shape of a square bar extending in the longitudinal direction. The spacing between the plurality of LED units 200 mounted on the flexible printed circuit board 220 increases gradually from the center of the flexible printed circuit board 220 to both edge regions.

The housing member 300 is formed in a box shape of a substantially rectangular parallelepiped having an open upper surface as shown in FIG. 4. That is, the housing member 300 includes a bottom surface 310, sidewalls 320 protruding vertically from three edges of the bottom surface 310, and an LED unit coupling portion provided at one edge of the bottom surface 310. 330). In this case, the light guide plate 100 is accommodated in the storage space 300 provided through the LED unit coupling part 330 and the side wall 320. The LED unit coupling part 330 is manufactured to have a substantially rectangular pillar shape having an empty inside, and a plurality of through holes 332 are provided at an upper side 331 thereof, and an inner side thereof is opened. Through this, the LED unit 200 passes through the through hole 332 and is inserted into the internal space of the LED unit coupling part 330. Then, the light of the LED unit 200 emitting side light through the open inner surface is guided to the light guide plate 100. The light reflection film may be provided on the inner surface of the LED unit coupling part 330. In this case, the flexible printed circuit board 220 on which the LED unit 200 is mounted is preferably bonded to the upper surface 331 of the LED unit coupling part 330 through an adhesive member. That is, the flexible printed circuit board 200 on which the LED unit 200 is mounted in the arrow direction of FIG. 4 is rotated 180 degrees so as to be coupled to the LED unit coupling part 330 of the accommodating member 300.

Hereinafter, a display device including the backlight described above will be described.

5 is an exploded perspective view of a display device including the backlight assembly according to an exemplary embodiment.

Referring to FIG. 5, the display device according to the present exemplary embodiment includes a display panel 1000 disposed above and a backlight 2000 disposed below.

The display panel 1000 includes a liquid crystal display panel including an upper substrate 500, a lower substrate 600, and a liquid crystal layer (not shown) provided therebetween. Although not shown, the driving circuit unit and the upper accommodating member may be further included.

In this case, the upper substrate 500 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. A common electrode made of a transparent conductor such as indium tin oxide (ITO) or indium zinc oxide (IZO) is coated on the entire surface of the upper substrate 500.

The lower substrate 600 is a transparent glass substrate on which a thin film transistor in matrix form is formed. The data line is connected to the source terminal of the thin film transistors, and the gate line is connected to the gate terminal. In addition, a pixel electrode made of a transparent electrode made of a transparent conductive material is formed in the drain terminal. When an electrical signal is input to the data line and the gate line, each of the thin film transistors is turned on or turned off to apply an electrical signal necessary for forming a pixel of the drain terminal. When the thin film transistor is turned on by applying power to the gate terminal and the source terminal of the lower substrate 600, an electric field is formed between the pixel electrode and the common electrode of the upper substrate 500, thereby forming the lower substrate 600 and the upper substrate. The arrangement of the liquid crystal layer injected between the substrates 500 is changed, and the light transmittance is changed according to the changed arrangement to obtain a desired image.

Although not shown, a predetermined circuit board may be further provided to apply a gate signal and a data signal to the gate line and the data line of the lower substrate 600, respectively.

The backlight 2000 includes a plurality of LED units 200 emitting light as shown in FIGS. 1 and 5, and a plurality of LED units having a higher density of the LED units 200 in a central region than in a peripheral region. A substrate 210 on which 200 is mounted,

A light guide plate 100 having one side adjacent to the plurality of LED units 200, a plurality of optical sheets 400 installed on the light guide plate 100, a substrate 210 on which the LED unit 200 is mounted, a light guide plate And an accommodating member 300 for accommodating the 100 and the optical sheet 400. A light reflecting plate (not shown) may be provided in an area between the light guide plate 100 and the accommodation member 300.

Here, the plurality of optical sheets 400 include a diffusion sheet, a polarizing sheet, and a brightness enhancing sheet, which are disposed on the light guide plate 100 to uniform the luminance distribution of the light emitted from the light guide plate 100.

As described above, in the present invention, a plurality of LED units are disposed adjacent to one side of the light guide plate so as to increase the separation distance between adjacent LED units from one side central area of the light guide plate to both edge regions. Luminance can be improved by increasing the amount of light supplied, and light loss in the edge region of the light guide plate can be prevented.

Although the invention has been described with reference to the accompanying drawings and the preferred embodiments described above, the invention is not limited thereto, but is defined by the claims that follow. Accordingly, one of ordinary skill in the art may variously modify and modify the present invention without departing from the spirit of the following claims.

Claims (11)

A plurality of LED units including at least one light emitting chip; And At least one side of the light guide plate disposed adjacent to the plurality of LED units; The backlight of the LED unit disposed in the central region of one side of the light guide plate is denser than both edge regions of one side. The method according to claim 1, The spacing between the plurality of LED units is gradually increasing toward both edges in the center of the light guide plate one side. The method according to claim 2, The spacing between the LED units are mirror-symmetric with respect to the center of the one side. The method according to claim 1, A backlight having a maximum separation distance between the LED units in the center region of one side of the light guide plate smaller than a minimum separation interval in both edge regions of the one side. The method according to claim 4, And a same distance between the LED units in the center region, and the same distance between the LED units in the edge regions. The method according to claim 1, And the plurality of LED units are mounted on a substrate or flexible printed circuit board. The method according to claim 1, The plurality of LED units include a red light emitting chip, a green light emitting chip and a blue light emitting chip, or a backlight including a white light emitting chip for emitting white light. A plurality of LED units including at least one light emitting chip that emits light, and a light guide plate having at least one side disposed adjacent to the plurality of LED units, wherein the density of the LED unit disposed in the central region of one side of the light guide plate is one; More dense backlight than both edge regions of the sides; And And a display panel configured to display an image by using light supplied from the backlight. The method according to claim 8, The backlight further includes a reflecting plate provided below the light guide plate, an optical sheet provided above the light guide plate, a receiving member accommodating the plurality of LED units and the light guide plate. The method according to claim 8, The separation distance between the plurality of LED units is gradually increased toward both edges from the center of one side of the light guide plate. The method according to claim 8, And a maximum separation distance between the LED units in the center region of one side of the light guide plate is smaller than a minimum separation interval in both edge regions of the one side.

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