KR101323516B1 - Backlight unit and liquid crystal display device having the same - Google Patents

Backlight unit and liquid crystal display device having the same Download PDF

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Publication number
KR101323516B1
KR101323516B1 KR1020060136166A KR20060136166A KR101323516B1 KR 101323516 B1 KR101323516 B1 KR 101323516B1 KR 1020060136166 A KR1020060136166 A KR 1020060136166A KR 20060136166 A KR20060136166 A KR 20060136166A KR 101323516 B1 KR101323516 B1 KR 101323516B1
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South Korea
Prior art keywords
light
light emitting
emitting diode
emitting diodes
light source
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KR1020060136166A
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Korean (ko)
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KR20080061171A (en
Inventor
곽영재
김남수
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엘지디스플레이 주식회사
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Priority to KR1020060136166A priority Critical patent/KR101323516B1/en
Publication of KR20080061171A publication Critical patent/KR20080061171A/en
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Abstract

Disclosed is a backlight unit capable of preventing color separation and realizing uniform white light.

The backlight unit according to the present invention includes a plurality of light source packages each having first to third light emitting diodes for generating light of different colors and arranged in a planar manner, wherein each of the light source packages includes first to third light sources. The third light emitting diodes may be installed to be rotated in different directions (or positions) of the first to third light emitting diodes of the adjacent light source package.

Light-emitting diode, symmetry

Description

Backlight unit and liquid crystal display device having same {Backlight unit and liquid crystal display device having the same}

1 is a view showing a direct type backlight unit using a conventional light emitting diode.

2 shows a backlight unit according to the invention;

3 is a plan view illustrating a light emitting diode package of FIG. 2 arranged on a reflector.

4 is a detailed view of portion A of FIG.

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

110: light emitting diode unit 111: bottom case

114: light emitting diode package

114a to 114i: first to ninth light emitting diode packages

115a to 115c: optical sheet 116: printed circuit board

117: Reflective plate 118: cap

122, 126, and 130: first to third light emitting diodes

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

In general, a liquid crystal display (LCD) is a liquid crystal panel including a plurality of liquid crystal cells arranged in a matrix and a plurality of control switches for switching a video signal to be supplied to each of the liquid crystal cells. As a result, the amount of light transmitted from the backlight unit is adjusted to display a desired image on the screen.

The backlight unit includes a direct light type for irradiating the liquid crystal panel with light from a plurality of light sources disposed directly below the liquid crystal display device, and a light guide panel (LGP) according to the arrangement of the light sources. It can be broadly classified into an edge light type for transmitting light from a light source provided on the side wall to the liquid crystal panel. Cold edge fluorescent lamps (CCFL: Cold Cathode Fluorescent Lamps) are generally used as the light source in the edge light type and direct light type backlight units. Its low refresh rate makes it unsuitable for high definition and high resolution TVs and monitors.

Recently, a light emitting diode (LED) is spotlighted as a light source to replace the cold cathode fluorescent lamp (CCFL). In addition, the backlight unit is in the trend of miniaturization, thinness, and light weight. In accordance with the above trend, light emitting diodes (LEDs), which are advantageous in terms of power consumption, weight, and brightness, have been proposed instead of fluorescent lamps used in backlight units.

The light emitting diode is disposed on a printed circuit board in the form of a package consisting of red, green and blue light emitting diodes, and a cap surrounding the red, green and blue light emitting diodes to generate light.

The backlight unit using the light emitting diode turns on the light emitting diode package when the image is implemented in the liquid crystal panel in which the image is displayed. When voltage is applied to the red, green, and blue three-color light emitting diodes of the light emitting diode package, the emitted red, green, and blue light are totally reflected inside the cap several times through the cap of the light emitting diode package. Mixed with each other.

In this case, the cap is formed of a transparent material, for example, may be composed of a lens. The red, green, and blue light generated in the red, green, and blue light emitting diodes of the light emitting diode package are mixed to form uniform white light. As such, the white light generated by the LED package is irradiated onto the liquid crystal panel to display an image on the liquid crystal panel.

1 is a view schematically showing a conventional light emitting diode unit.

As shown in FIG. 1, the conventional light emitting diode unit 10 includes a plurality of light emitting diode packages 14 including a red light emitting diode 30, a green light emitting diode 22, and a blue light emitting diode 26. . In addition, a cap 18 is disposed on the LED package 14 in the conventional LED unit 10. The cap 18 may include a lens, as described above.

The red, green, and blue light emitting diodes 30, 22, and 26 provided in the light emitting diode package 14 are identically arranged in the light emitting diode package 14. The red, green, and blue light emitting diodes 30, 22, and 26 that are identically arranged in the light emitting diode package 14 generate red light, green light, and blue light, respectively. The red, green and blue light is color mixed through the cap 18 several times to become white light. The white light is irradiated to a liquid crystal panel (not shown).

Meanwhile, as the red, green, and blue light emitting diodes 30, 22, and 26 in the light emitting diode package 14 are arranged in the same manner, red, green, and blue light in a predetermined direction in the backlight unit using the light emitting diode unit 10. The color separation occurs on the liquid crystal panel. As a result, a color separation phenomenon occurs in which a red band, a green band, and a blue band appear on the liquid crystal panel. In addition, as the color separation occurs, white light cannot be uniformly mixed. Since the white light is not uniformly mixed, light efficiency and color reproducibility on the liquid crystal panel are inferior.

An object of the present invention is to provide a backlight unit capable of preventing color separation and a liquid crystal display device having the same.

It is an object of the present invention to provide a backlight unit capable of realizing uniform white light and a liquid crystal display device having the same.

A backlight unit according to the present invention for achieving the above object is a reflecting plate for reflecting light; And a plurality of light source packages formed on the reflector and having first to third light emitting diodes respectively generating light of different colors, and arranged in a planar manner, wherein the light source packages are light sources positioned at the center of the reflector. The first to third light emitting diodes of the light source packages are symmetrically positioned up, down, left and right with respect to the package.

According to an aspect of the present invention, a liquid crystal display device includes: a reflector reflecting light; And a backlight unit including a plurality of light source packages formed on the reflecting plate and having first to third light emitting diodes respectively generating light of different colors and arranged in a plane. And a liquid crystal panel to display an image by irradiating light generated from the plurality of light source packages, wherein the light source packages are first to third light emitting diodes of the light source packages based on the light source package positioned at the center of the reflector. They are symmetrically positioned up, down, left and right.

Hereinafter, embodiments according to the present invention will be described with reference to the accompanying drawings.

2 is a view showing a backlight unit according to the present invention.

As shown in FIG. 2, the backlight unit according to the present invention is configured to fix and support the light emitting diode unit 110 having the plurality of light emitting diode packages 114 arranged thereon and the light emitting diode unit 110. The bottom case 111 may include an optical sheet 115a, 115b, and 115c positioned above the light emitting diode unit 110 to diffuse and collect light generated by the light emitting diode unit 110.

The light emitting diode unit 110 includes a plurality of light emitting diode packages 114 and a printed circuit board 116 on which the plurality of light emitting diode packages 114 are mounted. The light emitting diode package 114 includes red, green, and blue light emitting diodes, and a cap disposed on the red, green, and blue light emitting diodes.

A detailed description of the light emitting diode package 114 will be described later with reference to FIG. 4.

In addition, the backlight unit according to the present invention is positioned between the bottom case 111 and the light emitting diode unit 110, and further includes a reflector plate 117 attached to the bottom case 111. The reflecting plate 117 is configured to increase the utilization efficiency of the light generated by the light emitting diode unit 110.

Light generated from the light emitting diode unit 110 is reflected by the reflecting plate 117 or directly incident on the optical sheets 115a, 115b, and 115c, and is evenly irradiated onto the front surface of the liquid crystal panel (not shown), and the liquid crystal The luminance of the image represented on the panel is increased to display an identifiable image.

3 is a plan view illustrating a light emitting diode package of FIG. 2 arranged on a reflector.

As illustrated in FIGS. 2 and 3, a plurality of light emitting diode units 110 are arranged for each line on the reflecting plate 117. To be precise, the reflector plate 117 is arranged a light emitting diode package 114 for generating white light. As described above, the light generated by the LED package 114 is reflected by the reflecting plate 117 and irradiated to the optical sheets 115a, 115b, and 115c.

FIG. 4 is a view showing portion A of FIG. 3 in detail.

As shown in FIG. 3 and FIG. 4, a plurality of light emitting diode packages 114 are arranged in the A portion. The plurality of light emitting diode packages 114 include first to third light emitting diodes 122, 126, and 130, respectively. In addition, the light emitting diode package 114 includes a cap 118 surrounding the first to third light emitting diodes 122, 126, and 130 on the first to third light emitting diodes 122, 126, and 130. do.

The first to third light emitting diodes 122, 126, and 130 are composed of light emitting devices emitting light of different wavelength ranges. For example, the first to third light emitting diodes 122, 126, and 130 may include a first light emitting diode 122 for generating light in a green wavelength range and a second light emitting diode for generating light in a blue wavelength range ( 126 and a third light emitting diode 130 for generating light in the red wavelength range.

The arrangement of the light emitting diodes 122, 126, and 130 for each wavelength range may be appropriately configured according to a desired color temperature range in consideration of the amount of light emitted from the light emitting elements for each wavelength. In the present invention, various arrangements of the light emitting diodes 122, 126, and 130 for each wavelength range are configured.

Green, blue, and red light emitted from the first to third light emitting diodes 122, 126, and 130 are mixed with each other while being totally reflected inside the cap 118 through the cap 118. The cap 118 is formed of a transparent material, for example, may be configured as a lens. The cap 118 is made of a material having a refractive index larger than a medium between the light emitting diode package 114 and the diffusion sheet 115a of the optical sheet to satisfy the total reflection condition.

For example, when the medium between the light emitting diode package 114 and the diffusion sheet 115a is air, the cap 118 is made of epoxy resin or polymethylmethacrylate (PMMA) having a refractive index of 1.49. Can be. Since the cap 118 has a larger refractive index than that of the air medium, the cap 118 totally reflects the light incident at an angle greater than the critical angle at its interface several times. Accordingly, the green, blue, and red light generated by the first to third light emitting diodes 122, 126, and 130 are mixed inside the cap 118 and emitted as white light.

As described above, the arrangement form of the first to third light emitting diodes 122, 126, and 130 provided in the light emitting diode package 114 may vary. The light emitting diode package 114 is rotatable. Therefore, in the present invention, the first to third light emitting diodes 122, 126, and 130 are positioned on the upper, lower, and left sides of the light emitting diode package located at the center of the reflector 117 on which the light emitting diode package 114 is arranged. Right and diagonally arranged in symmetry. Detailed description thereof is as follows.

The fifth LED package 114e is positioned at the center of the plurality of LED packages 114a to 114i arranged in the A portion. First to third light emission formed in each of the second and eighth LED packages 114b and 114h positioned above and below the fifth LED package 114e based on the fifth LED package 114e. The diodes 122, 126, 130 are arranged in a symmetrical form with respect to the center point of each light emitting diode package.

Further, first to third light emission formed in each of the fourth and sixth light emitting diode packages 114d and 114f positioned on the left and right sides of the fifth light emitting diode package 114e based on the fifth light emitting diode package 114e. The diodes 122, 126, 130 are arranged in a symmetrical form with respect to the center point of each light emitting diode package.

As described above, the plurality of light emitting diode packages 114a to 114i include first to third light emitting diodes 122, 126, and 130 arranged symmetrically up, down, left, and right with respect to a central portion. As the first to third light emitting diodes 122, 126, and 130 in the plurality of light emitting diode packages 114a to 114i are symmetrically arranged up / down, left / right, the plurality of light emitting diode packages 114a to 114i. Generates white light color-mixed in different directions from each other.

The first, second, and third light emitting diodes 122, 126, and 130 arranged in each of the plurality of light emitting diode packages 114a to 114i generate green, blue, and red light generated in different directions. Since the green, blue, and red light generated by the first to third light emitting diodes 122, 126, and 130 are generated in different directions, the cap 118 is also color-mixed in different directions.

By arranging the first to third light emitting diodes 122, 126, and 130 in different shapes in the plurality of light emitting diode packages 114a to 114i, the plurality of light emitting diode packages 114a to 114i are white in different directions. The light is emitted. The white light emitted in the same direction due to the white light emitted from the plurality of light emitting diode packages 114a to 114i may minimize color separation generated in the conventional backlight unit.

In addition, the plurality of light emitting diode packages 114a to 114i including the first to third light emitting diodes 122, 126, and 130 arranged in different directions generate uniform white light. Due to this, the backlight unit according to the present invention can increase the light efficiency and color reproducibility.

As described above, the backlight unit according to the present invention is color-mixed in different directions by arranging the first to third light emitting diodes so as to be symmetric up / down, left / right with respect to the center of the screen portion where the image is displayed. White light is emitted from various directions to prevent color separation.

As the color separation is prevented, the backlight unit according to the present invention generates uniform white light, thereby improving light efficiency and color reproducibility.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the following claims. .

Claims (8)

A reflector reflecting light; And A plurality of light source packages formed on the reflector and having first to third light emitting diodes for generating light of different colors, and arranged in a plane; The light source packages are backlight units in which first to third light emitting diodes of the light source packages are symmetrically positioned up, down, left, and right with respect to the light source package positioned in the center of the reflector. The method of claim 1, The first light emitting diode generates green light, The second light emitting diode generates blue light, And the third light emitting diode emits red light. The method of claim 1, And a optical sheet for diffusing and condensing the light generated by the plurality of light source packages. The method of claim 1, And a cap surrounding the first to third light emitting diodes on the first to third light emitting diodes. A reflector reflecting light; And a backlight unit including a plurality of light source packages formed on the reflecting plate and having first to third light emitting diodes respectively generating light of different colors and arranged in a plane. And It includes a liquid crystal panel which is irradiated with light generated by the plurality of light source package to display an image, And the light source packages are symmetrically positioned up, down, left, and right of the light source packages based on the light source package positioned at the center of the reflector. 6. The method of claim 5, The first light emitting diode generates green light, The second light emitting diode generates blue light, And the third light emitting diode generates red light. 6. The method of claim 5, And an optical sheet for diffusing and condensing the light generated by the plurality of light source packages. 6. The method of claim 5, And a cap surrounding the first to third light emitting diodes on the first to third light emitting diodes.
KR1020060136166A 2006-12-28 2006-12-28 Backlight unit and liquid crystal display device having the same KR101323516B1 (en)

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Application Number Priority Date Filing Date Title
KR1020060136166A KR101323516B1 (en) 2006-12-28 2006-12-28 Backlight unit and liquid crystal display device having the same

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KR101323516B1 true KR101323516B1 (en) 2013-10-29

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH113051A (en) * 1997-04-14 1999-01-06 Nichia Chem Ind Ltd Led display and display device using it
US20050001537A1 (en) * 2003-03-28 2005-01-06 Lumileds Lighting U.S., Llc Multi-colored LED array with improved brightness profile and color uniformity
JP2006258973A (en) * 2005-03-15 2006-09-28 Sony Corp Back-light device and liquid crystal display device
KR20080037167A (en) * 2006-10-25 2008-04-30 삼성전자주식회사 Liquid crystal display device and driving method of the same

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH113051A (en) * 1997-04-14 1999-01-06 Nichia Chem Ind Ltd Led display and display device using it
US20050001537A1 (en) * 2003-03-28 2005-01-06 Lumileds Lighting U.S., Llc Multi-colored LED array with improved brightness profile and color uniformity
JP2006258973A (en) * 2005-03-15 2006-09-28 Sony Corp Back-light device and liquid crystal display device
KR20080037167A (en) * 2006-10-25 2008-04-30 삼성전자주식회사 Liquid crystal display device and driving method of the same

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