KR20100034270A - Liquid crystal display device - Google Patents

Abstract

PURPOSE: A liquid crystal display device is provided to improve a color reproduction rate of a light-emitting diode package by forming a red pigment layer on the front side of a printed circuit board and obtain a screen of high quality. CONSTITUTION: A plurality of light-emitting diode packages(LED packages)(102) are arranged on the lower part of a liquid crystal panel(LCD panel)(101). The multiple light-emitting diode packages supply the light to the liquid crystal panel. Multiple light-emitting diode packages comprise a blue-LED chip and a yellow fluorescent material on the blue-LED chip. The multiple light-emitting diode packages are mounted on the front of a printed circuit board(PCB)(103). A red pigment layer(104) is formed on the domain of the front side except for the mounted domain of the light-emitting diode package.

Description

[0001] LIQUID CRYSTAL DISPLAY DEVICE [0002]

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device having a light emitting diode package having improved color reproducibility.

BACKGROUND ART In general, liquid crystal display devices have tended to be gradually widened due to their light weight, thinness, and low power consumption. Accordingly, the liquid crystal display device is widely used as a means for displaying a screen in portable computers, mobile phones, office automation equipment and the like.

In general, a liquid crystal display device displays a desired image on a screen by adjusting the amount of light transmitted according to image signals applied to a plurality of control switching elements arranged in a matrix.

The liquid crystal display includes a liquid crystal panel in which a color filter substrate as an upper substrate and a thin film transistor array substrate as a lower substrate are opposed to each other, and a liquid crystal layer is formed between the two substrates, and a scan signal and image information are supplied to the liquid crystal panel. It is configured to include a drive unit for operating.

Since the liquid crystal display is a non-light emitting device that does not emit light by itself, in order to implement an image, a light source for supplying light to the liquid crystal panel is required. Accordingly, the liquid crystal display includes a back light assembly including a light source for supplying light to the liquid crystal panel and a light guide plate, an optical sheet, and the like for converting light emitted from the light source into uniform white light. .

Light sources generating light in the backlight assembly include a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL), and a light emitting diode (LED).

Conventionally, a cold cathode fluorescent lamp is mainly used as a light source of a backlight assembly, but in recent years, a liquid crystal display device employing a light emitting diode, which is advantageous in power consumption, weight, and luminance, as a light source of a backlight assembly according to the trend toward miniaturization, thinness, and light weight of a liquid crystal display device. Is growing.

Hereinafter, a conventional liquid crystal display device will be described with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view illustrating a conventional liquid crystal display, and FIG. 2 is a perspective view illustrating a printed circuit board on which a light emitting diode package is mounted in FIG. 1.

As shown in Figs. 1 and 2, a conventional general liquid crystal display device includes a liquid crystal panel 1; A plurality of light emitting diode packages (2) for supplying light to the liquid crystal panel (1); A printed circuit board (3) on which the plurality of light emitting diode packages (2) are mounted; A light guide plate (5) for guiding light emitted from the light emitting diode package (2) toward the liquid crystal panel (1); A reflection plate 6 reflecting light leaking into the lower portion of the light guide plate 5 into the light guide plate 5; An optical sheet 7 for converting the light emitted from the light guide plate 5 and supplying the light to the liquid crystal panel 1; It consists of.

Although not shown in detail in the drawing, the LED package 2 is composed of a blue light emitting diode chip (not shown) and a yellow phosphor (not shown) formed on the blue light emitting diode chip (not shown) to emit white light. do.

The conventional liquid crystal display device having the above configuration has a problem in that color reproducibility is lowered due to low purity of red light in the light emitted from the LED package 2.

That is, referring to FIG. 3, which shows the emission spectrum of the LED package 2, the peak value of the blue light and the peak value of the green light are present in the conventional general liquid crystal display, but the peak value of the red light is not present. It can be seen that the low, the light emitting diode package 2 of low purity of red light has a low color reproduction problem.

FIG. 4 illustrates color coordinates of the color reproducibility of the LED package 2 in a conventional LCD. Referring to this, red, green, and blue color coordinates are connected in the NTSC (national television system comittee) method. Since the area of one triangle is 0.1582 and the area of the triangle connecting the red, green, and blue color coordinates of the light emitting diode package 2 of the conventional liquid crystal display device is 0.0725, the light emitting diode package provided in the conventional liquid crystal display device ( 2) shows that the color reproduction rate is much lower than that of NTSC.

Accordingly, the present invention is to solve the above problems, an object of the present invention is to provide a liquid crystal display device with improved display quality is provided with a light emitting diode package with improved color gamut.

Liquid crystal display device according to an embodiment of the present invention for achieving the above object, the liquid crystal panel; A plurality of light emitting diode packages disposed under the liquid crystal panel to supply light to the liquid crystal panel, the plurality of light emitting diode packages including a blue light emitting diode chip and a yellow phosphor on the blue light emitting diode chip; And a printed circuit board on which a plurality of light emitting diode packages are mounted on a front surface, and a red pigment layer is formed on a region of the front surface except for a region where the light emitting diode package is mounted. And a control unit.

In addition, a liquid crystal display device according to another preferred embodiment of the present invention for achieving the above object is a liquid crystal panel; A plurality of light emitting diode packages disposed under the liquid crystal panel to supply light to the liquid crystal panel, the plurality of light emitting diode packages including a blue light emitting diode chip and a yellow phosphor on the blue light emitting diode chip; And a printed circuit board on which a plurality of light emitting diode packages are mounted on a front surface, and a red pigment layer is formed on a region of the front surface except for a region where the light emitting diode package is mounted. It is configured to include, wherein the LED package is characterized in that the red, green, blue phosphor mixture is further applied on the yellow phosphor.

In the liquid crystal display device according to the preferred embodiment of the present invention having the above configuration, the color reproducibility of the LED package is improved by forming a red pigment layer on the front surface of the printed circuit board on which the LED package is mounted. .

In the liquid crystal display according to another exemplary embodiment of the present invention, a red pigment layer is formed on a front surface of a printed circuit board on which a light emitting diode package is mounted, and a red, green, and blue color is formed on a yellow phosphor of the light emitting diode package. Since the purity of the red light is improved by applying the phosphor mixture, color reproducibility is increased.

Accordingly, the liquid crystal display device according to the present invention has an advantage of providing a high quality screen to a user.

Hereinafter, a liquid crystal display according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 5 is a perspective view illustrating a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 6 is a cross-sectional view illustrating a cross-sectional view after some components of the liquid crystal display of FIG. 5 are assembled for convenience of description. FIG. 7 is a detailed perspective view illustrating a printed circuit board on which a light emitting diode package is mounted in the liquid crystal display of FIG. 5.

5 to 7, a liquid crystal display according to a preferred embodiment of the present invention includes a liquid crystal panel 101; Is disposed below the liquid crystal panel 101 to supply light to the liquid crystal panel 101, and includes a blue light emitting diode chip (not shown) and a yellow phosphor (not shown) on the blue light emitting diode chip (not shown) A plurality of light emitting diode packages 102; And a printed circuit board 103 having a plurality of light emitting diode packages 102 mounted on a front surface thereof, and a red pigment layer 104 formed in a region of the front surface except for a region in which the light emitting diode packages 102 are mounted. .

Each component of the liquid crystal display according to the preferred embodiment of the present invention having such a configuration will be described below.

Referring to FIG. 5, the liquid crystal panel 101 includes a color filter substrate as an upper substrate and a thin film transistor array substrate as a lower substrate, and a liquid crystal layer (not shown) is formed between the two substrates although not shown in detail in the drawing. It is.

Referring to FIG. 5, at least one side of the lower portion of the liquid crystal panel 101 includes a plurality of light emitting diode packages 102 for supplying light to the liquid crystal panel 101, and the light emitting diode package 102 emits blue light. It comprises a diode (not shown) and a yellow phosphor (not shown).

That is, although not shown in detail in the drawing, the light emitting diode package 102 is formed to surround a blue light emitting diode chip (not shown) that emits blue light and at least the light emitting portion of the blue light emitting diode chip. It is comprised by the yellow fluorescent substance (not shown) which is excited by and generate | occur | produces yellow light.

As described above, in the LED package 102 including the blue LED chip and the yellow phosphor, a part of the blue light emitted from the blue LED chip excites the yellow phosphor to generate yellow light. The remaining blue light which is not excited is mixed with the yellow light generated by the yellow phosphor to produce white light.

The light emitting diode package 102 having such a configuration and light emitting principle is mounted on the printed circuit board 103.

5 to 7, the printed circuit board 103 has a plurality of light emitting diode packages 102 mounted on a front surface thereof, and the light emitting diode 102 is mounted on the printed circuit board 103. Wiring for connecting to the package driver (not shown) is formed.

In addition, a red pigment layer 104 is formed in a region of the front surface of the printed circuit board 103 except for a region where the LED package 102 is mounted, thereby increasing the color reproducibility of the LED package 102. There is an effect, which will be described in detail below with reference to FIG. 9.

In the drawing referred to in the above description, the red pigment layer 104 is formed on the upper and lower regions of the LED package 102 as well as the region between the plurality of LED packages 102 on the front surface of the printed circuit board 103. Although the present invention is not limited thereto, the red pigment layer 104 is formed only on the left and right regions of the LED package 102 on the front surface of the printed circuit board 103. Various examples are possible without departing from the scope of the invention.

That is, referring to FIG. 8, which shows another example of the red pigment layer 204 formed on the front surface of the printed circuit board 203, the printed circuit board on which the light emitting diode 202 is mounted is mounted in the liquid crystal display according to the present invention. 203 is a red pigment only in the region between the plurality of light emitting diode packages 202, as well as the left region of the leftmost light emitting diode package 202 and the right region of the rightmost light emitting diode package 202. The range in which the red pigment layer 204 is formed may be sufficiently changed depending on the size of the printed circuit board 203 or the size and mounting position of the LED package 202, such as the layer 204 is formed.

5 and 6, the liquid crystal panel 101 including the printed circuit board 103 is disposed inside a case to prevent flow and to protect it from external shocks. In the description of the present invention, only the lower cover 108 in which the printed circuit board 103 is disposed is referred to.

That is, the printed circuit board 103 is disposed inside the lower cover 108 such that the rear surface contacts the inner side surface of the lower cover 108.

In addition, a light guide plate 105 for guiding the light emitted from the LED package 102 toward the liquid crystal panel 101 is disposed in the lower cover 108. A reflecting plate 106 is disposed to reflect the light leaked to the lower portion of the light guide plate 105 into the light guide plate 105, and converts light from the light guide plate 105 to the liquid crystal panel 101 on the light guide plate 105. An optical sheet 107 is disposed, and the optical sheet 107 includes a plurality of sheets such as a prism sheet, a diffusion sheet, a protective sheet, and the like.

FIG. 9 is a graph showing color coordinates of the color reproducibility of the LED package 102 provided in the liquid crystal display according to the preferred embodiment of the present invention. In order to explain the effect of the present invention, NTSC (national television system committee) The color coordinate of the method) and the color coordinate of the light emitting diode package provided in the conventional general liquid crystal display device are shown together.

In addition, Table 1 below shows the area of the triangle connecting the red, green, and blue color coordinate values, the red, green, and blue color coordinate values in the color coordinate graph of FIG. 9, and the color reproducibility according to the area. It was.

Color coordinates (x, y)  area  Color reproduction rate [%] Red green blue  NTSC x axis 0.67 0.21 0.14  0.1582  100 y axis 0.33 0.71 0.08  Prior art x axis 0.579 0.353 0.145  0.0725  45.8 y axis 0.353 0.573 0.134  Invention x axis 0.6117 0.342 0.144  0.0862  54.5 y axis 0.3181 0.580 0.133

In this case, the color reproducibility is a range of colors that can be expressed by various types of display devices including a liquid crystal display, and is determined by color coordinates (x, y) determined by the international commission on illumination (CIE).

That is, the color reproducibility is calculated by comparing the area of the triangles connecting the red, green, and blue color coordinates (x, y) with the areas of the red, green, and blue color coordinates (x, y) of the NTSC system. The color reproducibility of the area of the color coordinates (x, y) of the red, green, and blue color of the NTSC system is relative.

9 and Table 1, it can be seen that the area of the triangle connecting each of the red, green, and blue color coordinates (x, y) in the NTSC method is 0.1582, and the color reproducibility at this time is 100 [% ] Is assumed. In the conventional general liquid crystal display device, the area of the triangle connecting the red, green, and blue color coordinates (x, y) of the light emitting diode package (see 2 in FIGS. 1 and 2) is 0.0725, and the color reproducibility is 45.8. It can be seen that it is [%]. In addition, in the liquid crystal display according to the preferred embodiment of the present invention, the area of the triangle connecting the red, green, and blue color coordinates (x, y) of the LED package 102 is 0.0862, and the color reproducibility is 54.5 [. %].

As such, the LED package 102 of the LCD according to the preferred embodiment of the present invention has a color gamut closer to the NTSC method than the LED package of the conventional LCD (see FIGS. 1 and 2). Therefore, there is an advantage of providing a high quality screen to the user.

10 illustrates a light emitting diode package 302 of a liquid crystal display according to another exemplary embodiment of the present invention for further increasing the color reproducibility of the light emitting diode package 302.

10, a liquid crystal display according to another exemplary embodiment of the present invention includes a liquid crystal panel (not shown); Disposed under the liquid crystal panel to supply light to the liquid crystal panel, the blue light emitting diode chip 302a, the yellow phosphor 302b on the blue light emitting diode chip 302a, the red on the yellow phosphor 302b, A plurality of light emitting diode packages 302 comprising a mixture 302c of green and blue phosphors; And a printed circuit board on which a plurality of light emitting diode packages 302 are mounted, and a red pigment layer (not shown) is formed in an area of the front surface except for a region in which the light emitting diode package 302 is mounted. .

The emission spectrum of the LED package 302 coated with the mixture 302c of red, green, and blue phosphors on the yellow phosphor 320b is illustrated in FIG. 11, and FIG. 11 shows the effects of the present invention. For the purpose of explanation, the emission spectrum of the LED package 302 included in the conventional LCD is also shown. In this case, FIG. 11 is an experiment for a case where a red, green, and blue phosphor mixture 302c is coated on a yellow phosphor 302b of the LED package 302 without forming a red pigment layer on the front surface of the printed circuit board. The result is.

Referring to FIG. 11, the peak value of red light does not exist in a light emitting diode package (see 2 of FIGS. 1 and 2) of a conventional liquid crystal display, but the light emitting diode package of the liquid crystal display according to the present invention ( In 302, it can be seen that not only peak values of blue and green light but also peak values of red light exist.

As such, when the red, green, and blue phosphor mixtures 302c are applied onto the yellow phosphor 302b of the light emitting diode package 302, peak values exist for blue, green, and red light, and thus, blue, green, It can be seen that all of the red light has a high purity and thus high color reproducibility will be obtained.

Of course, FIG. 11 illustrates an experiment in which a red, green, and blue phosphor mixture 302c is applied to a yellow phosphor 302b of the LED package 302 without forming a red pigment layer on the front surface of the printed circuit board. As a result, it can be seen that a high color reproducibility will be obtained as described above, and at the same time, a red pigment layer is formed on the front surface of the printed circuit board and red, green, and blue on the yellow phosphor 302b of the LED package 302. When applying the mixture of phosphors 302c, higher color reproducibility will be obtained.

As described above, in the liquid crystal display device according to the preferred embodiment of the present invention, the color reproducibility of the LED package can be improved by forming a red pigment layer on the front surface of the printed circuit board on which the LED package is mounted.

In addition, the liquid crystal display device according to another embodiment of the present invention, in addition to forming a red pigment layer on the front surface of the printed circuit board on which the LED package is mounted, the red, green and blue phosphors on the yellow phosphor of the LED package; Further application of the mixture improves the purity of the red light, resulting in higher color reproducibility.

Therefore, the present invention has the advantage of providing a user with a liquid crystal display device for displaying a high quality screen.

1 is a cross-sectional view showing a cross section of a conventional general liquid crystal display device.

FIG. 2 is a perspective view illustrating a printed circuit board on which a light emitting diode package is mounted in FIG. 1; FIG.

3 is a graph showing an emission spectrum of the LED package of FIG.

FIG. 4 is a graph showing color coordinates showing color gamut of the LED package of FIG. 1; FIG.

5 is a perspective view showing a liquid crystal display according to a preferred embodiment of the present invention.

FIG. 6 is a cross-sectional view illustrating a cross section after some components of the liquid crystal display of FIG. 5 are assembled for convenience of description; FIG.

7 is a perspective view illustrating in detail a printed circuit board on which a light emitting diode package is mounted in FIG. 5;

8 is a perspective view illustrating another example of a red pigment layer formed on a front surface of a printed circuit board in a liquid crystal display device according to a preferred embodiment of the present invention.

FIG. 9 is a view illustrating color coordinates of the color reproducibility of the light emitting diode package of FIG. 5. The color coordinates of the NTSC type and the color coordinates of the light emitting diode package included in the conventional general liquid crystal display are also shown.

10 is a view showing a light emitting diode package of a liquid crystal display according to another exemplary embodiment of the present invention.

FIG. 11 is a graph illustrating an emission spectrum of the light emitting diode package of FIG. 10. FIG. 11 is a graph showing an emission spectrum of a light emitting diode package included in a conventional liquid crystal display.

** Description of the symbols for the main parts of the drawings **

101: liquid crystal panel 102: light emitting diode package

103: printed circuit board 104: red pigment layer

105: LGP 106: Reflector

107: optical sheet 108: lower cover

Claims (4)

A liquid crystal panel; A plurality of light emitting diode packages disposed under the liquid crystal panel to supply light to the liquid crystal panel, the plurality of light emitting diode packages including a blue light emitting diode chip and a yellow phosphor on the blue light emitting diode chip; And A printed circuit board having a plurality of light emitting diode packages mounted on a front surface thereof, and a red pigment layer formed on an area of the front surface except for a region where the light emitting diode package is mounted; Liquid crystal display device comprising a. The liquid crystal display device according to claim 1, wherein the light emitting diode package is further coated with a mixture of red, green, and blue phosphors on a yellow phosphor. The liquid crystal display of claim 1, wherein the red pigment layer of the printed circuit board is partially formed only in the left / right regions of the LED package. The liquid crystal display device according to claim 1, wherein the red pigment layer of the printed circuit board is formed on the entire area of the front surface of the printed circuit board except for the area where the light emitting diode package is mounted.

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