KR100989163B1 - back light assembly - Google Patents

Abstract

The present invention relates to a backlight assembly capable of reducing manufacturing costs by reducing the number of light sources and displaying dynamic images by selectively providing high luminance light to a specific portion of a display unit of a liquid crystal panel. A backlight assembly provided in the liquid crystal panel, the backlight assembly comprising: a plurality of light sources for emitting light; A plurality of light guide plates arranged in one line of the light sources so as to correspond to the respective light sources and receiving the light emitted from the light sources and providing the light to the display unit of the liquid crystal panel; It includes a plurality of light scattering means formed in each of the light guide plate to have a different length corresponding to each wavelength of the light emitted from the light source.

Liquid crystal display, backlight assembly, light guide plate, light emitting diode

Description

Back light assembly {back light assembly}

1 is a perspective view of a backlight assembly using a conventional light emitting diode

2 is a perspective view of a backlight assembly according to a first embodiment of the present invention;

3 is a cross-sectional view of the backlight assembly taken along line II-II ′ of FIG. 2;

4 is an exploded perspective view of the light guide plate of FIG. 2;

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7 is an exploded perspective view of a light guide plate of a backlight assembly according to a second embodiment of the present invention;

* Explanation of symbols on the main parts of the drawings

113: outer case 115a: diffuser plate

115b: polarizing film 117: reflecting plate

118: light source 120: light guide plate

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly, to a backlight assembly capable of reducing a manufacturing cost by reducing the number of light sources and expressing a dynamic image by emphasizing the luminance of a specific portion of the liquid crystal panel.

In recent years, research on flat panel display devices has been actively conducted. Among them, liquid crystal display devices (LCDs), field emission display devices (FEDs), electro-luminescence display devices (ELDs), and PDPs (PDPs) Plasma Display Pannels).

Among them, LCD is the most widely used as a substitute for CRT (Cathode Ray Tube) for the use of mobile image display device because of the excellent image quality, light weight, thinness and low power consumption. In addition, it is being developed in various ways, such as a television for receiving and displaying broadcast signals, and a monitor of a computer.

As described above, although various technical advances have been made in order for the liquid crystal display device to serve as a screen display device in various fields, the task of improving the image quality as the screen display device has many advantages and disadvantages.

Therefore, in order to use a liquid crystal display device in various parts as a general screen display device, the key to development is how much high definition images such as high definition, high brightness, and large area can be realized while maintaining the characteristics of light weight, thinness, and low power consumption. It can be said.                         

Such a liquid crystal display device may be broadly divided into a liquid crystal panel displaying an image and a driving unit for applying a driving signal to the liquid crystal panel, wherein the liquid crystal panel includes a space between the first and second substrates, and It consists of the liquid crystal layer injected between the 1st, 2nd board | substrate.

The first substrate (TFT array substrate) may include a plurality of gate lines arranged in one direction at a predetermined interval, a plurality of data lines arranged at regular intervals in a direction perpendicular to the gate lines, and the respective gates. A plurality of pixel electrodes formed in a matrix form in each pixel region defined by crossing lines and data lines, and a plurality of thin film transistors switched by signals of the gate lines to transfer signals of the data lines to the pixel electrodes. Formed.

The second substrate (color filter substrate) includes a black matrix layer for blocking light in portions other than the pixel region, R, G, and B color filter layers for expressing color colors, and a common electrode for implementing an image. Is formed.

The first and second substrates have a predetermined space by spacers and are bonded by a sealant to form a liquid crystal between the two substrates.

Since the liquid crystal display itself is non-luminescent, a separate external light source for irradiating light is required.

 In particular, in the case of a transmissive liquid crystal display, a separate dimming device, ie, a back light assembly, for emitting and guiding light to the rear surface of the liquid crystal display panel is necessary.                         

Here, the backlight assembly includes an edge type method and a direct type method.

In the direct type, a light emitting lamp is disposed on a flat surface. Since the shape of the fluorescent lamp is displayed on the liquid crystal panel, the gap between the fluorescent lamp and the liquid crystal display panel must be maintained, and light scattering means is disposed for uniform distribution of light. There is a limit to thinning because it must be.

In addition, as the liquid crystal display panel becomes larger, the area of the light exit surface of the backlight assembly also increases. When the direct type is enlarged, the light exit surface is not flat unless sufficient light scattering means is secured. For this reason, the thickness of the light scattering means should be sufficiently secured.

On the other hand, in the edge type method, one fluorescent lamp is installed at the outside and light is distributed to the entire surface by using the light guide plate. One fluorescent lamp is installed at the side, and the light emitted from the fluorescent lamp passes through the light guide plate. Since there is a problem that the brightness is low.

In addition, high optical design and processing techniques for the light guide plate are required for uniform distribution of luminance.

Since the direct type and edge type have their disadvantages, the direct type backlight assembly is mainly used in the liquid crystal display where brightness is more important than the screen thickness, and the thickness is the same as that of a notebook PC or a monitor PC. In the liquid crystal display device of which importance is important, an edge type backlight assembly is mainly used.

Currently, as part of implementing a high brightness backlight assembly, a light emitting diode having high brightness and excellent color reproducibility is used as the light source.

Hereinafter, a backlight assembly using a conventional light emitting diode will be described in detail with reference to the accompanying drawings.

1 is a perspective view of a backlight assembly using a conventional light emitting diode.

As shown in FIG. 1, a conventional backlight assembly using a light emitting diode includes a light emitting diode array 19 including a plurality of light emitting diodes 18 and an upper portion of the light emitting diode array 19. A diffuser plate 15a for receiving the light emitted from the light source 18 to uniformly diffuse the light, and an upper portion of the diffuser plate 15a to transmit light uniformly diffused from the diffuser plate 15a. And an outer case 13 having a polarizing film 15b for increasing the luminance of the light and providing the light to the display unit of the liquid crystal panel, and accommodating the components 18, 19, 15a, and 15b and having a reflective plate 17 therein. Consists of

The backlight using the conventional light emitting diode configured as described above is configured to irradiate the light emitted from the plurality of light emitting diodes 18 evenly over the entire display portion of the liquid crystal panel through the diffusion plate 15a and the polarizing film 15b. do.

Here, the diffusion plate 15a prevents the shape of the light emitting diodes 18 from appearing on the display surface of the liquid crystal panel, directs the light emitted from the light emitting diodes 18 toward the display side of the liquid crystal panel, and Allows incidence at an angle in the range.

In general, the diffusion plate 15a is formed by coating a light diffusion member on both sides of a film made of a transparent resin.                         

Since the light emitted from the diffusion plate 15a has a large viewing angle as diffuse light, the front viewing angle of the liquid crystal display is improved by narrowing the viewing angle using the polarizing film 15b positioned above the diffusion plate 15a. Can reduce power consumption

In addition, the reflective plate 17 attached to the inner surface of the outer case 13 allows the light emitted from the light emitting diodes 18 to be irradiated to the display side of the liquid crystal panel to maximize the utilization efficiency of the light. have.

In the backlight assembly using the conventional light emitting diode 18 configured as described above, the light emitting diode 18 operates at 5V DC and thus does not require a separate inverter. However, a circuit for controlling current to protect the light emitting diodes 18 is provided.

However, the backlight assembly using the conventional light emitting diode has the following problems.

The backlight assembly using the conventional light emitting diodes requires a large number of light emitting diodes, thereby increasing manufacturing costs.

In addition, since the light emitting diode emits light having a higher luminance than a fluorescent lamp, when a large number of light emitting diodes are used in the backlight assembly as in the related art, the internal temperature of the light emitting diodes is increased, so that the light emitting diodes are increased. There is a problem in that the brightness of the light emitting diode is reduced because it does not operate normally.                         

In addition, since the conventional backlight assembly provides light of a constant luminance to all areas of the liquid crystal panel, there is a limit in expressing a dynamic image.

The present invention has been made to solve the above problems, the plurality of light sources arranged on the lower side of the liquid crystal panel, the light guide plate is arranged on one side of each light source, the light emitted from the light source inside the light guide plate By forming light scattering means capable of transmitting light having a higher luminance than the light transmitted by the light guide plate according to the wavelength, the number of light sources can be reduced, and light having a higher luminance than other regions is provided in a specific region of the liquid crystal panel. It is an object of the present invention to provide a backlight assembly capable of representing an image.

According to an aspect of the present invention, there is provided a backlight assembly comprising: a plurality of light sources for emitting light, the backlight assembly being provided under the liquid crystal panel to provide light to the liquid crystal panel; A plurality of light guide plates arranged in one line of the light sources so as to correspond to the respective light sources and receiving the light emitted from the light sources and providing the light to the display unit of the liquid crystal panel; It characterized in that it comprises a plurality of light scattering means formed in each of the light guide plate to have a different length corresponding to each wavelength of the light emitted from the light source.

Here, each of the light sources is characterized by using a light emitting diode.

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The light scattering means may be attached to an upper surface of the inside of each of the light guide plates so as to have a length perpendicular to the top surface of each of the light guide plates.

The length of each light scattering means is characterized in that the length of 1/4 for each wavelength of light emitted from the light source.

Wherein each of the light scattering means is arranged in order of length, the light scattering means having the shortest length is disposed closest to the light source, and the light scattering means having the longest length is disposed farthest from the light source.

Each light scattering means is attached to a lower surface of the light guide plate outside to have a length parallel to the lower surface of each light guide plate.

The length of each light scattering means is characterized in that it has a length of 1/2 with respect to each wavelength of light emitted from the light source.

Each light scattering means is characterized in that the distance is closer to the distance from the light source.

A diffusion plate and a polarizing film formed on the plurality of light guide plates; A reflection plate formed under the plurality of light guide plates; And an outer case formed surrounding lower and side surfaces of the plurality of light guide plates.

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Hereinafter, a backlight assembly according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a perspective view of a backlight assembly according to a first embodiment of the present invention, FIG. 3 is a cross-sectional view of the backlight assembly taken along line II-II ′ of FIG. 2, and FIG. 4 is an exploded perspective view of the light guide plate of FIG. 2. .

A backlight assembly according to a first embodiment of the present invention includes a liquid crystal panel (not shown) for displaying an image, as shown in FIGS. 2, 3 and 4; A plurality of light sources 118 arranged in one row at a lower side of the liquid crystal panel to emit light; A plurality of light guide plates 120 arranged in one line of the light sources 118 so as to correspond to the respective light sources 118 and receiving the light emitted from the light sources 118 to provide to the display unit of the liquid crystal panel; The light guide plate 120 is formed to have different lengths, and selectively scatters the light according to the wavelength of the light emitted from the light source 118 so as to have a higher luminance than the light transmitted by the light guide plate 120. Is transmitted to the display unit of the liquid crystal panel and a plurality of light scattering means 130 for selectively emphasizing the brightness of a specific region of the display unit of the liquid crystal panel, and the lower and side surfaces of the light guide plate 120 and the reflection plate therein 117 is formed and consists of an outer case 113 for supporting the plurality of light sources 118.

Here, a diffusion plate 115a for receiving light from the light guide plate 120 to uniformly diffuse the light and an upper portion of the light guide plate 120 and positioned above the diffusion plate 115a may be used. The polarizing film 115b is further provided to receive the light uniformly diffused from the 115a to increase the brightness of the light and provide it to the display unit of the liquid crystal panel.

In addition, a plurality of fine patterns 140 may be disposed on the lower outer surface of the light guide plate 120 so that light incident from the light source 118 into the light guide plate 120 may be uniformly transmitted to the end of the light guide plate 120. ) Is formed.

Here, the fine patterns 140 are formed such that the distance between the fine patterns 140 becomes closer as the distance from the light source 118 increases.

This is because the light incident on the light guide plate 120 is farther away from the light guide plate 120, the light intensity of the light becomes weaker, and the farther away from the light guide plate 120, the more tightly the interval between the fine patterns 140 is configured. This is for the better reflection of the light.

In addition, a reflecting plate 117 is formed under the light guide plate 120 to reflect light passing through the light guide plate 120 back to the light guide plate 120.

That is, the light emitted from the light source 118 to the light guide plate 120 is reflected by the light guide plate 120 according to the angle incident to the light guide plate 120 and proceeds toward the liquid crystal panel, or The light is not reflected on the lower surface of the light guide plate 120 and passes through the lower surface of the light guide plate 120. The reflective plate 117 reflects light that is not reflected and is lost to the light guide plate 120. It serves to convey.

In summary, the reflector plate 117 is to increase the efficiency of the light emitted from the light source 118 by minimizing the light lost to the outside.

On the other hand, the plurality of light scattering means 130 formed in the light guide plate 120 is formed to have a different length, as shown in FIG.

Specifically, each of the light scattering means 130 has a length (L) perpendicular to the upper surface of the light guide plate 120, is formed on the upper surface inside the light guide plate 120, the light source 118 It is formed to have a length (L) corresponding to each wavelength of the light incident on the light guide plate 120 through.

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Here, the relationship between the wavelength of each light and the length of the light scattering means 130 will be described in detail.

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As shown in FIG. 4, each of the light scattering means 130 scatters light of the wavelength most effectively when the light scattering means 130 has a length of about 1/4 of the wavelength of each light.

That is, when the light output from the light source 118 is incident to the light guide plate 120, the light is the light scattering means 130 corresponding to the wavelength of the light (that is, the light scattering means 130 of the Since it is further scattered in the light scattering means 130 having a length of 1/4 of the wavelength of light, the light incident on the light guide plate 120 exhibits a higher luminance in the light scattering means 130 region corresponding to the wavelength of the light. .

Therefore, the light transmitted to the display unit of the liquid crystal panel through the light scattering means 130 has a higher luminance than the light transmitted to the display unit of the liquid crystal panel through the light guide plate 120.

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Specifically, the length of each light scattering means 130 is defined by the following formula (1).

L = λ * 1/4

Here, L denotes the length of the light scattering means 130, and λ denotes the wavelength of the light emitted from the light source 118.
By forming a plurality of light scattering means 130 having a 1/4 length with respect to the wavelength to correspond to the specific region of the display unit of the liquid crystal panel, the luminance of the specific region of the display unit of the liquid crystal panel can be higher than other regions.

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In this way, the length of the light scattering means 130 is longer in proportion to the wavelength of the light, wherein the light scattering means 130 is arranged so as to have a longer length away from the light source 118 to the light source 118 It is preferable to allow the light emitted from) to be smoothly transmitted to each of the light scattering means (130).

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7 is an exploded perspective view of a light guide plate of a backlight assembly according to a second embodiment of the present invention.

That is, as shown in FIG. 7, the light scattering means 230 is formed on the lower surface outside the light guide plate 220 so as to have a length L parallel to the lower surface of each light guide plate 220.

However, at this time, when the light scattering means 230 has a length of about 1/2 with respect to the wavelength of the light emitted from the light source 218, it is most efficiently scattered light incident from the light guide plate 220.

Therefore, each light scattering means 220 has a length of about 1/2 corresponding to each wavelength of the light emitted from the light source 218.

Specifically, the length of each light scattering means 230 is defined by the following formula (2).

L = λ * 1/2

Here, L represents the length of the light scattering means 230, and λ represents the wavelength of the light emitted from the light source 218.

In addition, the light scattering means 230 is formed such that the distance between each light scattering means 230 is closer to the light source 118, as the fine pattern 140 in the first embodiment described above, It is preferable to allow the light emitted from 218 to be better transmitted to the end of the light guide plate 220 by the light scattering means 230.

In addition, the light scattering means 130 in the first embodiment and the light scattering means 230 in the second embodiment may be formed together.

However, when the light scattering means 130 according to the first embodiment and the light scattering means 230 according to the second embodiment are used together, the respective light scattering means 130 used in the first embodiment and Preferably, each of the light scattering means 230 used in the second embodiment is formed at a position corresponding to each other.

In this case, when the light scattering means 130 and 230 are formed together in the first and second embodiments, scattering of the light emitted from the light source 218 is further increased, so that the display portion of the liquid crystal panel has higher luminance. Light is transmitted.

That is, the light emitted from the light source 218 is incident and scattered by the light scattering means 230 formed on the lower surface of the light guide plate 220, and the scattered light is again formed on the light guide plate 220. It is incident on the 130 and scattered once more to have a higher luminance.

The present invention described above is not limited to the above-described embodiment and the accompanying drawings, and it is common in the art that various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be evident to those who have knowledge of.

The backlight assembly according to the present invention described above has the following effects.

First, since the number of the light sources can be greatly reduced by forming a plurality of light guide plates capable of transmitting light emitted from the light source to the liquid crystal panel on one side of the light source, the manufacturing cost of the backlight can be reduced.

Second, a plurality of light scattering means for scattering the light according to the wavelength of the light emitted from the light source to increase the brightness, formed in the light guide plate to correspond to a specific region of the display portion of the liquid crystal panel to specify the display portion of the liquid crystal panel Since an area may be brighter than another area, the liquid crystal panel may display a dynamic image.

Claims (11)

In the backlight assembly provided in the lower portion of the liquid crystal panel to provide light to the liquid crystal panel, A plurality of light sources for emitting light; A plurality of light guide plates arranged in one line of the light sources so as to correspond to the respective light sources and receiving the light emitted from the light sources and providing the light to the display unit of the liquid crystal panel; And a plurality of light scattering means formed in each of the light guide plates to have different lengths corresponding to respective wavelengths of light emitted from the light source; Each light source uses a light emitting diode. delete delete The method of claim 1, And each of the light scattering means is attached to an upper surface of the inside of each of the light guide plates so as to have a length perpendicular to the top surface of each of the light guide plates. The method of claim 4, wherein The length of each light scattering means has a length of 1/4 for each wavelength of light emitted from the light source. The method of claim 4, wherein Wherein each light scattering means is arranged in order of length, the light scattering means having the shortest length is disposed closest to the light source, and the light scattering means having the longest length is disposed farthest from the light source. The method of claim 1, And each light scattering means is attached to a bottom surface of the outside of the light guide plate so as to have a length parallel to the bottom surface of each light guide plate. The method of claim 7, wherein The length of each light scattering means has a length of 1/2 for each wavelength of light emitted from the light source. The method of claim 7, wherein Each of the light scattering means is formed so as to be closer to the distance from the light source closer assembly. The method of claim 1, A diffusion plate and a polarizing film formed on the plurality of light guide plates; A reflection plate formed under the plurality of light guide plates; And an outer case formed surrounding lower and side surfaces of the plurality of light guide plates. delete

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