KR20080086122A - White light emitting device and backlight unit and liquid crystal display device having the same - Google Patents

Abstract

A white light-emitting device, and a backlight unit and an LCD(Liquid Crystal Device) comprising the same are provided to mix color lights efficiently and improve the display quality by using a mixing member for mixing red, green, and blue lights emitted from a plurality of LEDs(Light-Emitting Diodes). A backlight unit(120) supplies light to an LCD panel(110). The backlight unit includes a support main formed of a square-shaped molding material, a plurality of LEDs(150) disposed on one end of the support main to emit the light, and a light-guiding plate(140) for converting point light into surface light. The backlight unit further includes optical sheets(130) disposed on the light-guiding plate to diffuse or collect the light, a reflecting sheet(160) disposed on a rear surface of the light-guiding plate, and a mixing member(190) disposed at a boundary surface between the light-guiding plate and the LEDs. The reflecting sheet reflects the light, which is outputted through the rear surface of the light-guiding plate, to the light-guiding plate, thereby reducing the loss of light. The mixing member mixes the lights, which are emitted from the LEDs, into white light. One surface of the mixing member faces a light exit surface of each of the LEDs, and the other surface of the mixing member faces a light incident surface of the light-guiding plate.

Description

White light emitting device, backlight unit and liquid crystal display device having the same {WHITE LIGHT EMITTING DEVICE AND BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY DEVICE HAVING THE SAME}

1 is an exploded perspective view showing a liquid crystal display according to an embodiment of the present invention.

FIG. 2 is a perspective view illustrating the light emitting diode and the mixing member of FIG. 1. FIG.

3 is a cross-sectional view illustrating a light emitting diode and a mixing member cut along the line II ′ of FIG. 2.

4 is a plan view illustrating a path of light incident from the light emitting diode of FIG. 1 to the mixing member.

FIG. 5 is a diagram illustrating a simulation color coordinate comparing a backlight unit having a mixing member according to an embodiment of the present invention with a conventional backlight unit. FIG.

6 is a view showing a light emitting diode and a mixing member according to another embodiment of the present invention.

7 is a cross-sectional view illustrating a light emitting diode and a mixing member cut along the line II-II ′ of FIG. 6.

8 is a plan view illustrating a path of light incident from the light emitting diode of FIG. 6 into the mixing member.

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

150: light emitting diodes 190, 290: mixing member

191 and 291: first incident part 191a: reflecting part

191b: second incident part 193, 295: first reflective material

195, 293: second reflective material

The present invention relates to a white light emitting device, and more particularly, to a white light emitting device capable of improving display quality, a backlight unit having the same, and a liquid crystal display device.

In recent years, the demand for high performance flat panel display devices has increased explosively, mainly due to the rapidly developing semiconductor technology.

The liquid crystal display (LCD), which has recently been in the spotlight among the flat panel display devices, can replace the conventional cathode ray tube (CRT) with the advantages of miniaturization, light weight, and low power consumption. It has been gradually attracting attention as a means, and is now used in almost all information processing apparatuses that require display devices.

The liquid crystal display converts the optical properties such as birefringence, optical dichroism, and light scattering characteristics of the liquid crystal cell into visual changes by applying a voltage to a specific molecular array of the liquid crystal and converting them into other molecular arrays. It is a display apparatus which displays information using the modulation of the light by a liquid crystal cell.

Since the liquid crystal display panel of the liquid crystal display device does not emit light by itself, the liquid crystal display panel includes a backlight unit that provides light to the liquid crystal display panel.

In small and medium-sized liquid crystal displays of mobile products such as cellular phones, light emitting diodes (LEDs) are provided as a light source of the backlight unit. Since the light emitting diode is a semiconductor device, it has a long life, a fast turn-on speed, low power consumption, strong impact resistance, and suitable for miniaturization and thinning.

However, the light emitting diode has a disadvantage in that light is not emitted from the light emitting diode in all directions due to the characteristic of the light emitting diode. In particular, in the case of a liquid crystal display device using three light emitting diodes of red (R), green (G), and blue (B), luminance is uneven in an adjacent area where the light emitting diodes are disposed due to the emission angle limit. There was. In addition, there was a problem of deterioration of the image quality in which red (R), green (G), and blue (B) are seen in the region (edge portion) where the light emitting diodes are disposed because they are not sufficiently mixed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a white light emitting device capable of improving non-uniform brightness and a backlight unit having the same.

Another object of the present invention is to provide a backlight unit and a liquid crystal display device having the same, which can improve the mixing of red, green, and blue light to improve the problem of deterioration of image quality.

A white light emitting device according to an embodiment of the present invention for achieving the above object,

At least one red, green, and blue light emitting diode; And

It includes a mixing member for emitting the light propagating vertically from the light emitting diode to the inclined plane with respect to the incident surface.

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

At least one red, green, and blue light emitting diode;

A mixing member which emits light propagating vertically from the light emitting diode at an angle of incidence with respect to the incident surface; And

It includes a light guide plate disposed to face the exit surface of the mixing member.

According to another embodiment of the present invention,

At least one red, green, and blue light emitting diode;

A mixing member which emits light propagating vertically from the light emitting diode at an angle of incidence with respect to the incident surface;

A light guide plate disposed to face the exit surface of the mixing member; And

And a liquid crystal display panel disposed on the light guide plate to display a predetermined image using light emitted from the light guide plate.

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 liquid crystal display according to an exemplary embodiment of the present invention.

As shown in FIG. 1, a liquid crystal display according to an exemplary embodiment includes a liquid crystal display panel 110 for displaying an image and a backlight unit 120 for providing light to the liquid crystal display panel 110. Include.

The liquid crystal display panel 110 includes a thin film transistor array substrate and a color filter substrate which are bonded to face each other to maintain a uniform cell gap, and a liquid crystal layer interposed between the thin film transistor array substrate and the color filter substrate.

Although not shown in detail, the thin film transistor array substrate is a transparent glass substrate on which a thin film transistor is formed on a matrix, and has a structure in which a data line is connected to a source terminal and a gate line is connected to a gate terminal. In addition, a pixel electrode made of transparent indium tin oxide (ITO) as a conductive material is connected to the drain terminal.

When an electrical signal is applied from the data line and the gate line, the electrical signal is transferred to the source terminal and the gate terminal of the thin film transistor. The thin film transistor is turned on or off according to the scan signal applied to the gate terminal through the double gate line, and the image signal applied to the source terminal through the data line is transferred or blocked to the drain terminal.

The color filter substrate disposed on the thin film transistor array substrate is a substrate in which a PGB color filter in which a predetermined color is expressed while light passes is formed by a thin film process, and a common electrode made of ITO is deposited on the RGB color filter.

When the thin film transistor is turned on, an electric field is formed between the pixel electrode of the thin film transistor array substrate and the common electrode of the color filter substrate. The liquid crystal injected between the thin film transistor array substrate and the color filter substrate by the electric field is changed in the array angle and light transmittance is changed according to the changed array angle to obtain a desired image.

Although the liquid crystal display panel 110 described above has described a transverse electric field method in which a common electrode is formed on a color filter substrate as an example, the present invention is not limited thereto, and the TN mode method in which both the pixel electrode and the common electrode are formed on the thin film transistor array substrate is described. May also be applied.

The backlight unit 120 that provides light to the liquid crystal display panel 110 includes a support main 170 made of a rectangular frame-shaped mold and a plurality of light emitting parts disposed at one end of the support main 170 to emit light. And a light guide plate 140 for converting the point light emitted from the light emitting diodes 150 into surface light.

The backlight unit 120 is disposed on the light guide plate 140 to diffuse and condense the light, and the light guide plate disposed on the rear surface of the light guide plate 140 and emitted to the rear surface of the light guide plate 140. Reflecting sheet 140 to reduce light loss by reflecting to the 140, and the light emitted from the light emitting diodes 150 disposed on the interface between the light guide plate 140 and the light emitting diodes 150 (White) Further comprising a mixing member 190 to be mixed.

The light guide plate 140, the mixing member 190, and the light emitting diodes 150 may be disposed to form one surface, and may be disposed at regular intervals from each other or in close contact with no play.

The light emitting diodes 150 include red LED light emitting diodes 150a, green LED light emitting diodes 150b, and blue LED light emitting diodes that emit red, green, and blue light. Made of a diode 150c.

One side of the mixing member 190 faces the emission surface (the surface from which light is emitted) of the light emitting diodes 150, and the other side of the mixing member 190 is the incident surface of the light guide plate 140 (the light is incident). Face to face).

A plurality of first incidence portions 191 are formed at one side of the mixing member 190 in a region corresponding to the emission surfaces of the light emitting diodes 150.

Although not shown in detail in the drawing, the first incidence part 191 includes a reflector (not shown) for reflecting light incident vertically to the inner surface of the mixing member 190, and the light reflected from the reflector is incident. A second incident part (not shown) is formed. That is, in the mixing member 190, light traveling vertically from the light emitting diodes 150 toward the first incident part 191 travels toward the inner surface of the mixing member 190 through the reflecting part and the second incident part. . Therefore, the mixing member 190 not only improves color mixing but also emits light incident vertically at an angle, thereby improving image quality deterioration of the edge portion.

Reflecting material (not shown) is applied to all surfaces of the mixing member 190 except for the other side of the mixing member 190 to face the incident part 191 and the light guide plate 140 to emit light. Is attached.

The reflector or reflector reflects light incident on the mixing member 190 to maximize color mixing and minimize light loss.

In the liquid crystal display according to the exemplary embodiment described above, a mixture of mixing red (R), green (G), and blue (B) light emitted from the light emitting diodes 150 into white (W) light is used. The member 190 may be provided to improve a problem of deterioration in image quality due to luminance imbalance and deterioration of color mixing that may occur around the region where the light emitting diodes 150 are disposed.

2 is a perspective view illustrating the light emitting diode and the mixing member of FIG. 1, and FIG. 3 is a cross-sectional view illustrating the light emitting diode and the mixing member cut along the line II ′ of FIG. 2, and FIG. 4 is the light emission of FIG. 1. A plan view showing a path of light incident from the diode to the mixing member.

As shown in FIG. 2 to FIG. 4, the mixing member 190 according to the exemplary embodiment of the present invention is positioned at the boundary area between the light emitting diodes 150a, 150b, 150c and the light guide plate 140.

The mixing member 190 has a rectangular parallelepiped shape.

One side of the mixing member 190 is formed with a plurality of first incidence portions 191 through which light emitted from the light emitting diodes 150a, 150b, and 150c is incident.

Light loss is applied to all surfaces of the mixing member 190 except for the plurality of first incident portions 191 formed on one side of the mixing member 190 and the other side of the mixing member 190 facing the light guide plate 140. In order to prevent the first reflective material 193 is applied. In an exemplary embodiment of the present invention, the first reflective material 193 is applied, but the present invention is not limited thereto, and a reflective body may be attached thereto.

The first incident part 191 is positioned to correspond to the light emitting diodes 150a, 150b, and 150c, respectively, and reflects the light emitted from the light emitting diodes 150a, 150b, and 150c to the inner surface of the mixing member 190. A reflection part 191a and a second incidence part 191b through which the light reflected from the reflection part 191a is incident into the mixing member 190 are formed.

The reflecting unit 191a reflects light of red (R), green (G), and blue (B) emitted from the light emitting diodes 150a, 150b, and 150c toward the inner side of the mixing member 190, thereby emitting light. Red (R), green (G), and blue (B) are visually visible in the corresponding regions (edge portions) by light traveling straight to the diodes 150a, 150b, 150c and the light guide plate 150 located on one surface. It serves to prevent problems that seem to appear.

The reflector 191a has a mountain shape protruding in the direction of the light emitting diodes 150a, 150b, and 150c, and has two surfaces inclined to the peak. On the two surfaces, a second reflecting material 195 is applied to change the light path in the direction of the second incidence portion 191b. Here, the second reflecting material 195 is, in one embodiment, attached. A reflector may be provided.

Although not shown in the drawing, a scattering pattern (not shown) may be formed in the second incident part 191b to diffuse light reflected from the reflecting part 191a into the mixing member 190.

Light of red (R), green (G), and blue (B) emitted from the light emitting diodes 150a, 150b, and 150c is reflected by the reflector 191a and is reflected by the reflector 191a. Is incident into the mixing member 190 through the second incident part 191b.

Looking at the path (→) of the light incident into the mixing member 190, it can be seen that the light of red (R), green (G) and blue (B) is continuously mixed inside the mixing member 190. .

Light mixed in the mixing member 190 is emitted through the other side of the mixing member 190. That is, the light emitted from the other side of the mixing member 190 is a light that proceeds inclined, and is incident on the incident surface of the light guide plate 140 facing the other side of the mixing member 190.

Light incident on the light guide plate 140 is irradiated to the liquid crystal display panel 110 of FIG. 1 via the light guide plate 140 and the optical sheets 130 (see FIG. 1).

In the backlight unit (120 of FIG. 1) according to the exemplary embodiment described above, the mixing member 190 is provided between the light emitting diodes 150a, 150b, and 150c and the light guide plate 140, so that the light emitting diodes 150a are provided. By mixing the light of red (R), green (G), and blue (B) emitted from 150b, 150c, it is possible to improve the deterioration of the image quality due to the reduction in color mixing.

In addition, the present invention converts the point light emitted from the light emitting diodes (150a, 150b, 150c) into the surface light by the mixing member 190 to enter the light of uniform brightness into the light guide plate 140, thereby improving the uneven brightness Can be.

FIG. 5 is a diagram illustrating a simulation color coordinate comparing a backlight unit having a mixing member and a conventional backlight unit according to an exemplary embodiment of the present invention.

As shown in FIG. 5, when looking at the color coordinates of the light emitted from the backlight unit according to an exemplary embodiment of the present invention, the center region (red line, L) of the color coordinates is a region representing white light and the backlight unit of the present invention. It can be seen that the light emitted from is focused on the white light.

It can be seen that the light (lime green bar) emitted from the conventional backlight unit without the mixing member (190 of FIG. 2) of the present invention concentrates not only in the center region of the color coordinate but also in other regions (red, green, and blue regions). Can be.

Therefore, the backlight unit according to the embodiment of the present invention is provided with a mixing member (190 of FIG. 2) to emit red (R), green (G), and blue (B) light emitted from the light emitting diodes. By mixing light), not only the luminance of the light incident on the light guide plate can be uniform, but also the path of light traveling vertically from the light emitting diodes can be changed to reduce image quality degradation caused by the light traveling vertically.

6 is a view showing a light emitting diode and a mixing member according to another embodiment of the present invention, FIG. 7 is a cross-sectional view showing a light emitting diode and a mixing member cut along the line II-II 'of FIG. 6 is a plan view illustrating a path of light incident from the light emitting diode of FIG. 6 to the mixing member.

As shown in FIGS. 6 to 8, the mixing member 290 according to another exemplary embodiment of the present invention is positioned at the boundary area between the light emitting diodes 150a, 150b, 150c and the light guide plate 140.

The mixing member 290 has an incident part 291 on which one side of the light emitted from the light emitting diodes 150a, 150b and 150c is incident to correspond to the light emitting diodes 150.

The incident part 291 has a round shape to diffuse incident light, and although not shown in detail, a scattering pattern (not shown) may be formed to maximize light diffusion.

The first reflective material 295 is coated on the other side of the mixing member 290 so as to correspond to the incident part 291. The first reflecting material 295 may be changed to a reflector having an attached shape.

On the other side of the mixing member 290 excluding the first reflective material 295, an emission part 292 may emit light.

The first reflective material 295 reflects light traveling straight from the light emitting diodes 150a, 150b and 150c to the light guide plate 140 via the mixing member 290 to correspond to the light emitting diodes 150a, 150b and 150c. Red (R), green (G) and blue (B) in the area (edge portion) to be a role to prevent the visible problem.

The second reflective material 293 is applied to all surfaces of the mixing member 290 except for the incident part 291 and the exit part 292 to minimize light loss. The second reflecting material 293 may be changed to a reflector in the form of attachment.

Looking at the path (→) of the light incident into the mixing member 290, the light of red (R), green (G) and blue (B) is reflected by the first and second reflective materials (295, 293) It can be seen that the mixture inside the mixing member 290.

The backlight unit according to another exemplary embodiment of the present invention described above has a round-shaped incidence portion 291 between the light emitting diodes 150a, 150b, and 150c and the light guide plate 140, and the first and second reflective materials 295,. A mixing member 290 including 293 is provided to mix the light of red (R), green (G), and blue (B) emitted from the light emitting diodes 150a, 150b, 150c, thereby reducing color mixing. It can be improved.

In addition, by reflecting light propagating vertically from the light emitting diodes 150a, 150b, and 150c, it is possible to improve the deterioration of image quality (in which red, green, and blue are displayed at the edge portion).

In addition, the present invention by converting the point light emitted from the light emitting diodes (150a, 150b, 150c) into the surface light by the mixing member 290 to enter the light of uniform brightness into the light guide plate 140, thereby improving the uneven brightness Can be.

In the above, a mixing member emitting white light by mixing red (R), green (G), and blue (B) light emitted from the plurality of light emitting diodes 150a, 150b, and 150c by using two embodiments. Although 190 and 290 are provided, the present invention is not limited thereto, and the first light incidence parts 191 and 291, the second light incidence part 191b and the reflection part 191a of the mixing members 190 and 290 that emit white light are not limited thereto. ). More embodiments may exist in the structure of the first and second reflecting materials 193, 195, 295, 293. Therefore, although not described above, any technology included in the technical scope of the present invention may be regarded as the technical idea of the present invention.

As described above, according to the present invention, there is provided a mixing member for mixing red, green, and blue light emitted from the plurality of light emitting diodes into white light to not only reduce color mixing but also light emitting diodes. There is an effect of improving the image quality deterioration in which red, green, and blue colors are displayed at the edge portions by reflecting light traveling vertically from the edge portion.

In addition, the present invention has the effect of improving the non-uniform brightness by converting the point light emitted from the light emitting diodes into the surface light and the incident light of uniform brightness into the light guide plate.

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.

Claims (15)

At least one red, green, and blue light emitting diode; And And a mixing member which emits the light propagating vertically from the light emitting diode at an inclined plane relative to the incident surface. The method of claim 1, The mixing member, A first incident part to which light is incident on one side of the mixing member corresponding to the at least one light emitting diode; A reflector reflecting light incident vertically through the first incidence portion toward an inner surface of the mixing member; And And a second incidence part through which light whose path is changed by the reflecting part is incident. The method of claim 2, The reflector is formed of a mountain shape protruding outward from one side of the mixing member, the white light emitting device, characterized in that made of at least two inclined surfaces inclined relative to the peak of the mountain. The method of claim 2, White light emitting device, characterized in that the reflective material is applied or a reflector is applied to all the surfaces of the mixing member except the first and second incidence and the exit portion of the mixing member. The method of claim 1, One side of the mixing member corresponding to the at least one light emitting diode is a round-shaped incidence in which light is incident, and the other side of the mixing member reflects light traveling perpendicular to the region corresponding to the incidence White light emitting device comprising a reflector. At least one red, green, and blue light emitting diode; A mixing member which emits light propagating vertically from the light emitting diode at an angle of incidence with respect to the incident surface; And And a light guide plate disposed to face the exit surface of the mixing member. The method of claim 6, The mixing member, A first incident part to which light is incident on one side of the mixing member corresponding to the at least one light emitting diode; A reflector reflecting light incident vertically through the first incidence portion toward an inner surface of the mixing member; And And a second incidence part through which light whose path is changed by the reflecting part is incident. The method of claim 7, wherein The reflector is formed of a mountain shape protruding outwardly from one side of the mixing member, the backlight unit, characterized in that made of at least two inclined surfaces inclined with respect to the peak of the mountain. The method of claim 7, wherein And a reflecting material is applied to all surfaces of the mixing member except for the first and second incidence portions and the emission portion of the mixing member. The method of claim 6, One side of the mixing member corresponding to the at least one light emitting diode is a round-shaped incidence in which light is incident, and the other side of the mixing member reflects light traveling perpendicular to the area corresponding to the incidence A backlight unit comprising a reflector. At least one red, green, and blue light emitting diode; A mixing member which emits light propagating vertically from the light emitting diode at an angle of incidence with respect to the incident surface; A light guide plate disposed to face the exit surface of the mixing member; And And a liquid crystal display panel disposed on the light guide plate to display a predetermined image by using light emitted from the light guide plate. The method of claim 11, The mixing member, A first incident part to which light is incident on one side of the mixing member corresponding to the at least one light emitting diode; A reflector reflecting light incident vertically through the first incidence portion toward an inner surface of the mixing member; And And a second incidence part through which light whose path is changed by the reflecting part is incident. The method of claim 12, And the reflector has a mountain shape protruding outwardly from one side of the mixing member, and includes at least two inclined surfaces inclined with respect to the peak of the mountain. The method of claim 12, A reflective material is coated or a reflector is attached to all surfaces of the mixing member except for the first and second incidence portions and the emission portion of the mixing member. The method of claim 11, One side of the mixing member corresponding to the at least one light emitting diode is a round-shaped incidence in which light is incident, and the other side of the mixing member reflects light traveling perpendicular to the region corresponding to the incidence Liquid crystal display comprising a reflector.

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