KR20080025482A - Backlight unit and liquid crystal dispaly - Google Patents

Abstract

A backlight unit and an LCD(Liquid Crystal Display) having the same are provided to improve optical characteristics, such as luminance, and implement a high-definition screen by installing the first lamp for high color reproduction and the second lamp for luminance compensation. A backlight unit(1) comprises an optical member(30), the first lamp(10), and the second lamp(20). The first lamp, adjacent to the lateral of the optical member, emits a light of high color reproduction. The second lamp, diagonally arranged at the rear of the first lamp, is provided to compensate for luminance. The first lamp emits visible rays. The second lamp has a light-emitting spectrum which can compensate for luminance, and emits green light. The first and second lamps respectively have power supply parts which can be individually driven.

Description

Backlight unit and liquid crystal display having same {Backlight unit and Liquid crystal dispaly}

1 is a view showing a conventional backlight unit.

2 is a view showing color coordinates of light emitted from a conventional backlight unit.

3 shows a backlight unit according to the invention;

4 is a view showing color coordinates of light emitted from a backlight unit according to the present invention;

5 is a diagram illustrating a spectrum of light emitted from a backlight unit according to the present invention.

<Description of the reference numerals for the main parts of the drawings>

 1: backlight unit 10: first lamp

20: second lamp 30: optical member

40: cover 45: lamp housing

The present invention relates to a backlight unit having a high color rendering lamp having a compensation lamp capable of improving optical characteristics in a diagonal direction to improve optical characteristics such as luminance, and a liquid crystal display device having the same.

Conventional liquid crystal display devices are light-receiving elements for displaying an image by controlling the amount of light source coming from the outside, so a separate light source for irradiating light to the liquid crystal panel with liquid crystal, that is, a backlight unit, is required. According to the location where the lamp unit is installed, it can be divided into edge type and direct type.

As described above, the liquid crystal display device has a different characteristic from that of the CRT device because it controls the amount of light transmitted through the screen using liquid crystal and determines the contrast and color of the screen using the light.

For example, the viewing angle of which the image quality varies depending on the viewing angle, the color reproducibility depending on how much the transmitted light passes through the color filter, etc. to reproduce the colors of red, green, and blue, and the luminance indicating the contrast of the screen .

Here, the liquid crystal display device has the advantages of light and thin, while the color reproducibility and luminance is weak compared to the CRT.

However, in the market of the liquid crystal display device, there is a demand for the development of a liquid crystal display device capable of realizing color reproducibility higher than the CRT level.

Since the conventional liquid crystal display obtains the brightness from the backlight unit, the brightness of the backlight unit may be increased to satisfy the demand for high brightness.

1 is a view illustrating a conventional backlight unit. Here, a light receiving element such as a liquid crystal display device includes a backlight unit capable of providing light.

As shown in FIG. 1, the backlight unit 501 may include a plurality of lamps 510 that may emit light.

The lamp 510 is supported by the cover 540 and the like, and protected by the lamp housing 545. In addition, the backlight unit 501 may provide an optical member 530 such as a reflector, a light guide plate, an optical film, etc. to increase the efficiency of light emitted from the lamp 510.

Here, the lamp 510 is formed in a tube shape with glass or the like, and the inert gas is filled in the tube shape. And fluorescent material is applied to the inner wall of the tube.

Here, an electrode is provided at the end of the tube to excite the inert gas by the electrons provided from the electrode, and the ultraviolet light generated by the excited electrons emits white light while passing through the fluorescent material.

2 is a view illustrating color coordinates of light emitted from a conventional backlight unit.

As shown in FIG. 2, the backlight unit 501 includes a lamp 510, and white light is emitted from the lamp 510. The display device using the backlight unit 501 may reproduce various colors by separating three primary colors of light from the white light provided from the backlight unit 501 and adding and mixing them.

Here, the lamp 510 uses CCFL, but the CCFL has a limit in color reproducibility.

The color of light emitted from the lamp is determined by chromaticity coordinates defined by the International Lighting Commission. That is, after calculating the tertiary value X, Y from an arbitrary light spectrum, the color coordinates X, Y of red, green, and blue can be obtained from the tertiary value by the transformation matrix.

Subsequently, when the X, Y values of red, green, and blue are represented as coordinates, a horn-shaped spectral trajectory is drawn, which is called a chromatic diagram (CIE). Normal light has its color coordinates inside of this horseshoe shape.

However, the CCFL has a narrow color coordinate. That is, the user requires a full spec capable of expressing various colors in the color coordinates, but the conventional CCFL has a specification capable of supporting a color corresponding to a narrow triangular area as shown in FIG. 2. There is only.

As such, the conventional lamp may have difficulty in implementing a screen capable of expressing various colors due to reduced color reproducibility supporting various colors.

That is, the conventional backlight unit does not satisfy the user's request for high brightness and high color purity.

The present invention provides a backlight unit capable of preventing deterioration of optical characteristics such as lifespan and luminance of a light source by providing a backlight unit with a light source capable of high color reproduction of a light source and a compensation light source positioned diagonally to the high color reproduction light source. The purpose is to provide.

Another object of the present invention is to provide a liquid crystal display device capable of displaying a clear image by employing a backlight unit having improved optical characteristics such as luminance.

The backlight unit according to the present invention for achieving the above object is an optical member; A first lamp adjacent to the side of the optical member and emitting light having high color reproducibility; And a second lamp disposed in a diagonal direction behind the first lamp and configured to compensate for luminance.

The second lamp has an emission spectrum capable of compensating for luminance.

According to an aspect of the present invention, there is provided a liquid crystal display device including: the backlight unit; It characterized in that it comprises a liquid crystal panel having a liquid crystal provided on the backlight unit.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The backlight unit of the present invention and a liquid crystal display device having the same may be embodied by those skilled in the art. It is intended for illustrative purposes and not limited to the following embodiments.

Recently, there is a demand for the development of a liquid crystal display device capable of realizing color reproducibility higher than the CRT level in the market of the liquid crystal display device.

In order to implement a high color reproducible liquid crystal display device, the emission spectrum of the light source provided in the backlight unit should be changed, and correspondingly, the transmission spectrum for maximizing the emission efficiency should be adjusted. That is, the backlight unit should be able to provide light capable of expressing various colors.

As such, requests for increasing brightness and improving color purity are prominent in the display. Users require a full spec display capable of expressing various colors, but conventional lamps have limitations in expressing various colors. Therefore, high color reproducibility lamps are required to satisfy the standard of full specification that can express various colors.

3 is a view illustrating a backlight unit according to the present invention.

Since a liquid crystal display device is a light receiving element, it requires a backlight unit capable of providing light. The liquid crystal display device has the advantages of light and thin.

Thus, as shown in FIG. 3, the backlight unit 1 may include a plurality of lamps as a light source. The light source may be a high color reproducible light source capable of improving color reproducibility, and may include a first lamp 10 and a second lamp 20 that may compensate for optical characteristics such as luminance.

Here, the first and second lamps 10 and 20 are provided with a cover 40 and a lamp housing 45 formed integrally with the cover 40.

The lamp housing 45 is accommodated inside the lamp housing 45 to protect the glass tubes of the first and second lamps 10 and 20. That is, the first and second lamps 10 and 20 that emit light may be disposed inside the lamp housing 45.

In addition, an optical member 30 may be provided at sides of the first and second lamps 10 and 20 to increase light efficiency. The optical member 30 may condense and diffuse light, change a path of light provided from the first and second lamps 10 and 20, and change the path of the light from the first and second lamps 10 and 20. The line light source which emits light can also be changed into a surface light source. As such, the backlight unit 1 may improve light efficiency by the optical member 30 provided with the light guide plate and the plurality of optical films.

In addition, the optical member 30 may form a backlight unit 1 capable of providing light in a predetermined direction by changing the path of the light while increasing the efficiency of the light provided from the first and second lamps 10 and 20. To be able.

The first and second lamps 10 and 20 may be disposed at both ends of the optical member 30 or may be provided at either end.

Here, the first lamp 10 is a light source capable of high color reproduction, and the second lamp 20 is a compensation light source capable of improving optical characteristics such as brightness of the backlight unit 1.

The first lamp 10 is a light source capable of providing an emission spectrum of white light. In other words, the first lamp 10 may be provided as a wide color gamut (WCG) to improve color reproducibility. As such, the light provided from the backlight unit 1 may form a wide color coordinate in the chromaticity diagram by forming the first lamp 10 as a high color reproducibility lamp.

The first lamp 10 is a high color reproduction lamp capable of forming a wide area of color coordinates by applying a phosphor capable of emitting a broad spectrum of visible light on the inner wall of the glass tube. The color coordinates and the phosphor of the first lamp 10 will be described later with reference to FIG. 4.

In addition, the second lamp 20 may be a light source having an emission spectrum of any one of three-way index red, green, and blue in order to compensate for optical characteristics such as luminance of the backlight unit 1. .

Here, the second lamp 20 may be a light source having a spectrum of luminance compensation green light that can compensate for a problem of luminance deterioration that may occur in the high color reproducibility first lamp 10 which will be described later. Alternatively, the light source may be a blue light source for minimizing a short cycle of lamp replacement due to short life time during the RGB. Here, a green light source that compensates for the luminance of the backlight unit 1 will be described later with reference to FIG. 5.

Since the emission spectrum of the first lamp 10 and the second lamp 20 are different from each other, the first lamp 10 having the emission spectrum of white light is disposed in an area adjacent to the optical member 30. desirable. In addition, the second lamp 20 may be disposed behind the first lamp 10 in order to compensate for optical characteristics of the white light emission spectrum of the first lamp 10.

That is, the second lamp 20 having the emission spectrum of any one of red, green, and blue may be provided to the optical member 30 together with the emission spectrum of the white light of the first lamp 10. The first lamp 10 may be disposed behind the first lamp 10 so as to compensate for optical characteristics such as brightness of the first lamp 10.

Here, the second lamp 20 is preferably disposed in the diagonal direction while being disposed behind the first lamp 10.

The first lamp 10 is disposed adjacent to the optical member 30, and the second lamp 20 is disposed diagonally to the rear of the first lamp 10 with respect to the optical member 30. It is preferable. This is because the second lamp 20 may provide an emission spectrum of any one of the visible light spectrums, so that when the second lamp 20 is disposed on the same phase in front of the first lamp 10 or in the vertical direction, the second lamp 20 The light may be provided to the optical member 30 as it is, so that only one light emission spectrum of the visible light spectrum may be provided to the optical member 30 to hinder the high color reproduction of the backlight unit 1.

When the light provided by the second lamp 20 to the optical member 30 is blocked by the first lamp 10, the light efficiency of the second lamp 20 emitting the compensation light may be reduced. . Thus, the second lamp 20 may be disposed in a diagonal direction behind the first lamp 10 to compensate for the optical characteristics of the first lamp 10.

Meanwhile, the first and second lamps 10 and 20 may individually drive. In an embodiment, when the use time of the first lamp 10 becomes long, the brightness of the first lamp 10 may decrease. However, luminance of the first lamp 10 and the second lamp 20 may be lowered depending on the usage time. However, since the luminance decrease does not decrease at a constant rate, a difference may occur between the luminance of the first lamp 10 and the luminance of the second lamp 20 according to the usage time of the first lamp 10. .

That is, the luminance of the second lamp 20, which is the compensation light source, becomes relatively strong according to the difference between the brightness of the first lamp 10 and the brightness of the second lamp 20, so that the backlight unit 1 emits even light. It can be difficult to do.

Therefore, the second lamp 20 and the first lamp 10 may be further provided with a power supply for driving each of the second lamp 20 and the like so as to control the brightness of the second lamp 20 and the like.

Therefore, the second lamp 20 is provided as a compensation light source having a first lamp 10 emitting white light and one of the red, green, and blue light emission spectra in a diagonal direction behind the first lamp 10. As a result, optical characteristics such as luminance of the backlight unit 1 can be improved.

4 is a view illustrating color coordinates of light emitted from a backlight unit according to the present invention. Here, the backlight unit 1 of the present invention has a configuration substantially the same as that of FIG. 3.

The backlight unit 1 includes first and second lamps 10 and 20 as light sources. The light source includes a first lamp 10 capable of high color reproduction, and a second lamp 20 as a compensation light source. Here, the first lamp 10 will be described.

On the other hand, the conventional backlight unit is known to be about 40 to 50% color reproducibility by the National Television System Committee (NTSC). However, a display device employing a conventional backlight unit replaces sharpness with the color reproducibility, and users are demanding a display device with a clearer screen.

Therefore, as an alternative to improve the color reproducibility of the backlight unit 1, there is an attempt to improve the color reproducibility by changing the composition of the phosphors formed in the first and second lamps 10 and 20 as light sources.

Briefly describing the light emitting mechanism of the light source, a tube-shaped glass tube is provided and an inert gas is filled in the tube-shaped inside of the glass tube. An electrode is provided at the end of the glass tube. In this case, phosphors are applied to the inner wall of the glass tube.

Here, the electrons may be accelerated by the voltage applied to the electrode to ionize the neutral atoms. In this case, a discharge plasma in which cations and anions coexist by continuous ionization may be formed. The electrons in the discharge plasma collide with the neutral inert gas to excite the inert gas atom.

Herein, the inert gas atom is excited, and the inert gas atom is excited and returns to the ground state to emit ultraviolet rays. The emitted ultraviolet rays are converted into visible light as they are incident on the phosphor applied to the inner wall of the glass tube.

As such, the visible light may be formed as ultraviolet light is incident on the phosphor. That is, the visible light may improve the color reproducibility of the backlight unit 1 by changing the composition of the phosphor.

Here, the phosphor may be Y (P, V) O ₄ : Eu, etc. as red, BAM: Eu, Mn, etc. may be used for green, and BAM: Eu, etc. may be used for blue. Therefore, the phosphor is formed of the fluorescent material as described above, thereby generating a light emission spectrum capable of high color reproduction.

As such, by changing the composition of the phosphor, it is possible to form a light source with high color reproducibility.

Thus, as shown in FIG. 4, the first lamp 10 may be provided as a wide color gamut (WCG) that may improve color reproducibility. Here, A is the color coordinate of the conventional CCFL, B is the color coordinate of the WCG which is the high color reproduction lamp of the present invention. In the present invention, the first lamp 10 having the color coordinate of B is used.

As such, the light provided from the backlight unit 1 may form a wide color coordinate in the chromaticity diagram by forming the first lamp 10 as a high color reproducibility lamp.

In other words, if the color reproducibility is expressed as

At this time, the triangular area formed by the color coordinates of red, green, and blue becomes the color reproduction area, and as the triangle area becomes larger, color reproducibility is improved. Color reproducibility depends on color purity, and as color purity increases, color reproducibility may increase. That is, the backlight unit 1 may reproduce various colors by the first lamp 10.

By the way, the color coordinate is a two-dimensional representation of only the information on the color without the information on the luminance from the tristimulus value obtained based on the orange function.

Here, the tertiary values X and Y represent weights of individual color-matching functions close to a spectrum, and in particular, Y represents a stimulus value for brightness.

In this way, the backlight unit 1 is capable of high color reproduction by the first lamp 10.

5 is a diagram illustrating a spectrum emitted from the backlight unit according to the present invention. C is a diagram showing the emission spectrum of the first lamp as a high color reproduction light source, D is a diagram showing the emission spectrum using the second lamp as a compensation light source from the first lamp. The backlight unit applies to FIG. 3 mutatis mutandis.

In order for the backlight unit 1 to be used in a high color reproducibility display device, the first and second lamps 10 and 20 used as light sources have high brightness. However, due to the first lamp 10, the backlight unit 1 may have improved color reproducibility while low luminance peak of green, which affects luminance, may lower optical characteristics such as luminance.

In other words, it is difficult to say that the backlight unit 1 using the first lamp 10, which is a high color reproducibility lamp, has an optical characteristic such as luminance that satisfies user requirements. Therefore, it is desirable to improve the brightness of the backlight unit 1 using the high color reproducibility lamp as the light source.

As shown in FIG. 5, C is an emission spectrum of the backlight unit 1 using a high color reproducibility lamp such as the first lamp 10, and D is a first lamp 10 which is a high color reproducibility lamp of the present invention. The emission spectrum of the backlight unit 1 of the present invention in which a second lamp 20 serving as a compensation light source is provided behind the first lamp 10 is illustrated.

C is a light emission spectrum of the backlight unit 1 using only the first lamp 10 of high color reproducibility. The first lamp 10 may have high color reproduction, but the luminance peak of the green light emission spectrum may be weakly formed.

On the other hand, D has a second lamp 20 as a compensation light source that can compensate for optical characteristics such as luminance behind the first lamp 10 that can reproduce high color.

The second lamp 20 may compensate for optical characteristics such as luminance of the first lamp 10. For example, the first lamp 10 may be weak in terms of luminance while being a light source capable of high color reproduction.

Therefore, the second lamp 20 capable of compensating for the weak luminance of the first lamp 10 may be provided as a light source that emits green light emission spectrum. Here, the second lamp 20 may be disposed diagonally behind the first lamp 10 as described with reference to FIG. 3.

In addition, the red, green, and blue light sources need more red / green light sources than blue light sources. Accordingly, when the red, green, and blue light sources have a 1: 1: 1 lighting time, The luminance may be improved by increasing the output intensity of the red / green light source rather than the output intensity of the blue light source. As such, by increasing the intensity of the light source that can recognize the brightness of the user's eyes, it is possible to improve optical characteristics such as luminance.

Therefore, in the present invention, the luminance of the backlight unit 1 may be improved by further providing a light source for emitting the green light. The second lamp 20 emits light capable of compensating for optical characteristics such as brightness of the backlight unit 1.

By providing the second lamp 20 as a light source for emitting green light, the amount of light in the first lamp 10 may be increased to improve the wavelength region of the green light. That is, the peak of the wavelength band of the green light region can be improved. Increasing the intensity may improve quantum efficiency, thereby improving brightness of the backlight unit 1.

As such, the backlight unit 1 using the high color reproduction lamp according to the present invention may further provide a green light source to satisfy the request for high brightness. Therefore, a second lamp 20 capable of providing green light may be provided in the backlight unit 1 to improve brightness.

In addition, in another embodiment, the second lamp 20 may be applied to a blue lamp having a short lifetime as a compensation light source. Briefly, the first lamp 10 has a short lifespan of blue. Therefore, the luminance of the blue light of the backlight unit 1 may be lowered due to the short lifetime of the blue fluorescent material. That is, the lifespan and luminance may be improved by compensating for the short-lived color.

Meanwhile, the backlight unit 1 may be used as the backlight of the display device. Since the liquid crystal display which is typically used among the display devices is not a self-luminous element, it requires a backlight unit 1 capable of providing light.

Since the liquid crystal display obtains the brightness from the backlight unit 1, the brightness of the backlight unit 1 may be increased to satisfy the demand for high brightness.

However, in view of the color reproducibility of the liquid crystal display device, there is a continuing demand for liquid crystal display devices having improved color reproducibility and improved luminance. Therefore, the liquid crystal display device requires a backlight unit 1 capable of high color reproducibility and improved luminance.

Therefore, in the present invention, the backlight unit 1 includes a first lamp 10 capable of high color reproduction and a second lamp 20 capable of improving optical characteristics such as brightness of the backlight unit 1. It is possible to provide a liquid crystal display device capable of displaying a clear screen by improving reproducibility and increasing luminance.

As such, it is possible to provide a display device capable of displaying a clear screen by improving color reproducibility and luminance of the backlight unit 1.

The backlight unit according to the present invention can improve the brightness of the backlight unit by providing a first lamp capable of high color reproduction and a second lamp that is a compensation light source capable of compensating for brightness and the like.

In addition, it is possible to implement a clear screen of a display device using the backlight unit by improving optical characteristics such as brightness of the backlight unit.

Claims (6)

Optical member; A first lamp adjacent to the side of the optical member and emitting light having high color reproducibility; And And a second lamp disposed in a diagonal direction behind the first lamp and configured to compensate for luminance. The method of claim 1, The first lamp is a backlight unit, characterized in that for emitting light in the visible region. The method of claim 1, And the second lamp has an emission spectrum capable of compensating for luminance. The method of claim 1, And the second lamp emits green light. The method of claim 1, And the first and second lamps each have a power supply unit capable of individually driving the backlight unit. A backlight unit according to any one of claims 1 to 6; And a liquid crystal panel having liquid crystal provided on the backlight unit.

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