KR20100002460A - Backlight unit and method of manufacturing the same - Google Patents

Abstract

PURPOSE: A backlight unit for embodying brightness and a manufacturing method thereof are provided to irradiate uniform light without increase of the thickness of the backlight unit. CONSTITUTION: A transparent substrate(221) includes a first side for radiating a light and an opposite side of the first side and the second side. A light emitting device is arranged in the second side of the transparent substrate. The light created in the emitting device is arranged so that a reflection plate(223) face with the second side. In order that the emitting device is driven, a conductive line of the transparent substrate is patterned in the second side. A sealing material layer(224) is formed by using the encapsulating material for the second side of the transparent substrate.

Description

BACKLIGHT UNIT AND METHOD OF MANUFACTURING THE SAME}

The present invention relates to a backlight unit and a method for manufacturing the same, and more particularly, to a backlight unit and a method for manufacturing the same, which can reduce the overall thickness and improve the intensity of light and the uniformity of color.

In general, a liquid crystal display device is a passive display device without a light source of its own, and requires a backlight unit such as a lamp, a light guide plate, and sheets, which plays an important role in the performance of the liquid crystal display device. Such a backlight unit is a key variable in the overall weight reduction of the liquid crystal display device. Recently, as a liquid crystal display device is used for a television receiver, a liquid crystal display device has been enlarged. Accordingly, a direct type backlight unit having a light source disposed under the liquid crystal display device has been widely used. Light sources such as CCFL and EEFL have been used as such direct type backlight units, but in recent years, backlight units employing light emitting diodes (LEDs) as light sources have been increasing in order to reduce color consumption and power consumption of displayed images.

1 is a schematic cross-sectional view of a liquid crystal display device employing a conventional backlight unit.

Referring to FIG. 1, the conventional liquid crystal display device 100 includes a liquid crystal display panel 110 and a backlight unit 120. The liquid crystal display panel 110 includes a color filter substrate 111, a TFT substrate 112, and a liquid crystal layer (not shown) interposed between the color filter substrate 111 and the TFT substrate 112. The TFT substrate 112 includes pixels arranged in a plurality of matrix shapes, and the transmittance of light is changed by rearranging liquid crystal molecules according to the magnitude of the voltage to which the pixels are applied.

The backlight unit 120 irradiates light to the liquid crystal display panel 110, and the liquid crystal display panel 110 displays an image by adjusting the transmittance of light provided from the backlight unit 120 according to the arrangement of liquid crystals of each pixel. do.

In this case, when the light provided to each portion of the liquid crystal display panel 110 is not uniform or the color is not uniform, the image displayed on the liquid crystal display panel 110 becomes poor.

On the other hand, when the backlight unit 120 adopts a light emitting device 122 such as a light emitting diode (LED), the light emitting diode irradiates light within a predetermined angle (θ) range, so that the diffusion plate 123 and the light emitting diode If not spaced apart by a predetermined distance (d), a dark portion is generated in the space between the light emitting diodes. In order to solve this problem, when the light emitting diodes and the diffusion plate 123 are separated by a predetermined distance d, the overall thickness of the backlight unit 120 may be increased.

In addition, the plurality of light emitting devices 122 adopted in the backlight unit 120 may not have the same characteristics, and the degree of deterioration of the fluorescent layer of each light emitting device 122 may be changed in a driving process. Therefore, the color coordinates of each pixel may change, resulting in deterioration of image quality of the liquid crystal display.

Accordingly, the first problem to be solved by the present invention is to provide a backlight unit that can reduce the overall thickness and improve the intensity of light and the uniformity of color.

The second object of the present invention is to provide a method of manufacturing such a backlight unit.

The backlight unit according to an embodiment of the present invention for solving this problem includes a transparent substrate, a light emitting device and a reflecting plate.

The transparent substrate includes a first surface for emitting light and a second surface opposite thereto. The light emitting device is mounted on the second surface of the transparent substrate, and the reflecting plate is disposed to face the second surface to reflect the light generated by the light emitting device toward the second surface.

For example, the transparent substrate may include a conductive wiring patterned on the second surface to drive the light emitting device.

For example, the conductive wiring patterned on the transparent substrate may include an indium compound of transparent conductivity, or the conductive wiring patterned on the transparent substrate may be formed of a transparent electrode film.

For example, a light emitting diode package can be used as the light emitting element. In this case, at least two of the blue, green, and red light emitting diode packages may be used.

The backlight unit is attached to the first surface of the transparent substrate, further comprises a phosphor film for converting the light generated in the light emitting diode package to white light, or inside the transparent substrate is generated in the light emitting diode package Fluorescent particles may be scattered to convert light into white light.

Alternatively, an unpackaged light emitting diode chip can be used as the light emitting element. In this case, at least two of the blue, green, and red light emitting diode chips may be used. The backlight unit may be attached to the first surface of the transparent substrate and further include a phosphor film for converting light generated from the light emitting diode chip into white light, or inside the transparent substrate may be generated from the light emitting diode chip. Fluorescent particles for converting light into white light may be scattered.

An encapsulant layer may be interposed between the transparent substrate and the reflective plate to be encapsulated. In addition, fluorescent particles may be dispersed in the encapsulant layer to change the light generated by the light emitting diode chip into white light.

According to one or more exemplary embodiments, a method of manufacturing a backlight unit includes forming a transparent conductive layer on a second surface of a transparent substrate including a first surface for emitting light and a second surface opposite to the second surface, and forming the transparent conductive layer. Patterning a conductive wiring, attaching a light emitting device to be connected to the conductive wiring, and fixing the reflective plate to face the second surface.

For example, the transparent conductive layer may be formed using an indium compound such as indium tin oxide (ITO) or indium zinc oxide (IZO), or the transparent conductive layer may be formed of a transparent electrode film. It can be formed by attaching to two sides.

For example, a light emitting diode package packaged as the light emitting device may be attached to the transparent substrate. At this time, the transparent substrate, the fluorescent particles for changing the light generated in the light emitting diode package to white light may be used that is scattered therein.

Alternatively, a light emitting diode chip which is not packaged as the light emitting device may be attached to the transparent substrate. At this time, the transparent substrate, the fluorescent particles for changing the light generated from the light emitting diode chip to white light may be used that is scattered therein. Alternatively, a light emitting diode chip which is not packaged as the light emitting device may be attached to the transparent substrate.

The method of manufacturing the backlight unit may further include forming an encapsulant layer by coating a transparent encapsulant on the transparent substrate to which the light emitting element is attached, after attaching the light emitting element, and curing the encapsulant layer. have. In this case, before the hardening of the encapsulant layer, the method may further include dispersing fluorescent particles in the encapsulant layer to change light generated from the light emitting diode chip to white light.

According to the present invention, the light emitting device can be mounted opposite to the light emitting device to irradiate uniform light without increasing the thickness of the backlight unit.

In addition, since the light generated by the reversely mounted light emitting device randomly passes through the phosphor layer, uniform color coordinates and brightness can be realized.

As the inventive concept allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, the terms "comprise" or "having" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art, and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not. Throughout the specification, the light emitting diode 'chip' refers to a device in an unpackaged state, and the term 'package' refers to a device in a packaged state.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a cross-sectional view schematically illustrating a backlight unit according to an exemplary embodiment of the present invention.]

Referring to FIG. 2, the backlight unit 220 according to an exemplary embodiment of the present invention includes a transparent substrate 221, a light emitting device 122, and a reflecting plate 223.

The transparent substrate 221 is formed of a transparent insulating material. For example, the transparent substrate 221 may include glass or plastic. The transparent substrate 221 includes a first surface A for emitting light and a second surface B opposite thereto. Although not shown, a conductive wiring for driving the light emitting device 122 is formed on the second surface B. Referring to FIG. The conductive wiring (not shown) may be formed of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO), and a transparent electrode film formed by coating a transparent polymer on a carbon nanotube (CNT) layer. It can be formed as.

The light emitting device 122 is mounted on the second surface B of the transparent substrate 221. For example, a white light emitting diode package using an encapsulant including a yellow fluorescent material such as YAG in a blue light emitting diode chip may be used as the light emitting device 122. Alternatively, a red light emitting diode, a green light emitting diode, and a blue light emitting diode may be grouped to form a white light emitting diode group.

As the light emitting device 122, a light emitting device emitting blue or green light may be used. In this case, as described later, a red fluorescent material is used, and when a light emitting device emitting blue or red light is used, a green fluorescent material is used. May be used to emit white light.

The reflective plate 223 reflects the light generated by the light emitting element 122 toward the second surface B. As shown in FIG.

Optionally, an encapsulant layer 244 may be formed in a space between the light emitting device 122 and the reflecting plate 223. In this case, the reflective plate 223 may be formed by coating a metal material having excellent reflectance on the surface of the encapsulant layer 244, or may be simply attached with a metal tape.

According to the backlight unit 220 according to the present embodiment, the light generated by the light emitting element 122 is reflected by the reflecting plate 223 and is incident on the transparent substrate 221 at various angles, and the transparent substrate 221 is Since the light is guided and distributed evenly, as in the light guide plate, the uniformity of the intensity of the light may be ensured even when the diffusion plate 123 and the light emitting device 122 are not separated by a predetermined distance d as shown in FIG. 1. Therefore, the overall thickness of the backlight unit 220 can be reduced.

Moreover, the backlight unit 220 according to the present embodiment does not adopt the diffuser plate 123 shown in FIG. 1. Therefore, the overall thickness of the backlight unit 220 can be further reduced and manufacturing cost can be reduced.

3 is a cross-sectional view schematically showing a backlight unit according to another exemplary embodiment of the present invention. The backlight unit 320 illustrated in FIG. 3 is substantially the same except for the backlight unit 220 and the phosphor film 301 illustrated in FIG. 2. Therefore, the same components will be denoted by the same reference numerals and redundant descriptions will be omitted.

Referring to FIG. 3, the backlight unit 320 according to the present embodiment includes a transparent substrate 221, a light emitting element 122, a reflecting plate 223, and a phosphor film 301.

As the light emitting device 122, for example, a blue light emitting diode package or a blue light emitting diode chip may be used.

The phosphor film 301 is disposed on the first surface A of the transparent substrate 221. In the phosphor film 301, for example, yellow phosphor particles may be scattered therein, and red phosphor particles and green phosphor particles are scattered to change blue light generated by the light emitting device 122 to white light.

For example, the light emitting device 122 may have a wavelength in a range of about 410 nm to 500 nm, and YAG: Ce yellow phosphor, silicate-based green phosphor, selenium-based red phosphor, etc. may be used as phosphor particles in the phosphor film 301. Can be used.

According to the backlight unit 320 according to the present embodiment, the light generated by the light emitting element 122 is reflected by the reflecting plate 223 and is incident on the transparent substrate 221 at various angles, and the transparent substrate 221 is Since the light is guided and dispersed as in the light guide plate, as shown in FIG. 1, the uniformity of the intensity of the light may be ensured even when the diffuser plate 123 and the light emitting device 122 are not separated by a predetermined distance d. Therefore, the overall thickness of the backlight unit 320 may be reduced.

In addition, the backlight unit 320 according to the present exemplary embodiment does not adopt the diffusion plate 123 illustrated in FIG. 1. Therefore, the overall thickness of the backlight unit 320 can be further reduced and manufacturing cost can be reduced.

In addition, since the light emitting devices 122 all generate a single blue light, a problem of arranging red, green, and blue light emitting diodes for white light emission can be solved. In addition, in the present embodiment, even if the blue light with deviations generated from the different blue diodes are mixed with each other inside the transparent substrate 221, the case of using a white light emitting diode package containing a phosphor to solve the alignment problem It is possible to solve the color deviation problem between the white light emitting diode package, which may occur.

4 is a cross-sectional view schematically illustrating a backlight unit according to yet another exemplary embodiment of the present invention. The backlight unit 420 illustrated in FIG. 4 is substantially the same except for the backlight unit 220 and the transparent substrate 421 illustrated in FIG. 2. Therefore, the same components will be denoted by the same reference numerals and redundant descriptions will be omitted.

Referring to FIG. 4, the backlight unit 420 according to the present exemplary embodiment includes a transparent substrate 421, a light emitting element 122, and a reflecting plate 223.

As the light emitting device 122, for example, a blue light emitting diode package or a blue light emitting diode chip may be used.

Yellow phosphor particles may be scattered in the transparent substrate 421, and red phosphor particles and green phosphor particles are scattered to change blue light generated by the light emitting device 122 to white light.

For example, the light emitting device 122 may have a wavelength in a range of approximately 410 nm to 500 nm, and YAG: Ce yellow phosphor, silicate green phosphor, selenium red phosphor, etc. may be formed as phosphor particles in the transparent substrate 421. Can be used.

According to the backlight unit 420 according to the present embodiment, the light generated by the light emitting element 122 is reflected by the reflecting plate 223 and is incident on the transparent substrate 421 at various angles, and the transparent substrate 421 is Since the light is guided and dispersed as in the light guide plate, as shown in FIG. 1, the uniformity of the intensity of the light may be ensured even when the diffuser plate 123 and the light emitting device 122 are not separated by a predetermined distance d. Thus, the overall thickness of the backlight unit 420 may be reduced. Furthermore, by employing the transparent substrate 421 as the phosphor layer without employing the phosphor film 301 of FIG. 3, the thickness of the phosphor film 301 can be further reduced.

In addition, the backlight unit 420 according to the present exemplary embodiment does not employ the diffusion plate 123 illustrated in FIG. 1. Therefore, the overall thickness of the backlight unit 420 can be further reduced and manufacturing cost can be reduced.

In addition, since the light emitting devices 122 all generate a single blue light, a problem of arranging red, green, and blue light emitting diodes for white light emission can be solved. In addition, in the present embodiment, even if the blue light with deviations generated from the different blue diodes are mixed with each other inside the transparent substrate 221, the case of using a white light emitting diode package containing a phosphor to solve the alignment problem It is possible to solve the color deviation problem between the white light emitting diode packages, which may occur.

5 is a schematic cross-sectional view of a backlight unit according to still another exemplary embodiment of the present invention. The backlight unit 520 illustrated in FIG. 5 is substantially the same except for the backlight unit 220 and the encapsulant layer 524 illustrated in FIG. 2. Therefore, the same components will be denoted by the same reference numerals and redundant descriptions will be omitted.

Referring to FIG. 5, the backlight unit 320 according to the present exemplary embodiment includes a transparent substrate 421, a light emitting device 122, a reflective plate 223, and an encapsulant layer 524.

As the light emitting device 122, for example, a blue light emitting diode package or a blue light emitting diode chip may be used.

Yellow phosphor particles may be scattered in the encapsulant layer 524, and red phosphor particles and green phosphor particles are scattered to change the blue light generated by the light emitting device 122 to white light.

For example, the light emitting device 122 may have a wavelength in a range of approximately 410 nm to 500 nm, and YAG: Ce yellow phosphor, silicate green phosphor, selenium red phosphor, etc. may be formed as phosphor particles in the encapsulant layer 524. Can be used.

According to the backlight unit 520 according to the present embodiment, the light generated by the light emitting element 122 is reflected by the reflecting plate 223 and is incident on the transparent substrate 221 at various angles, and the transparent substrate 221 is Since the light is guided and dispersed as in the light guide plate, as shown in FIG. 1, the uniformity of the intensity of the light may be ensured even when the diffuser plate 123 and the light emitting device 122 are not separated by a predetermined distance d. Therefore, the overall thickness of the backlight unit 520 can be reduced.

In addition, the backlight unit 520 according to the present exemplary embodiment does not adopt the diffusion plate 123 illustrated in FIG. 1. Therefore, the overall thickness of the backlight unit 520 can be further reduced and manufacturing cost can be reduced. Furthermore, by using the encapsulant layer 524 as the phosphor layer without employing the phosphor film 301 of FIG. 3, the thickness of the phosphor film 301 can be further reduced.

In addition, since the light emitting devices 122 all generate a single blue light, a problem of arranging red, green, and blue light emitting diodes for white light emission can be solved. In addition, in the present exemplary embodiment, even though blue light having deviations generated from different blue diodes is mixed with each other in the transparent substrate 421, a white light emitting diode package containing phosphors is used to solve an alignment problem. It is possible to solve the color deviation problem between the white light emitting diode packages, which may occur.

6 to 9 are perspective views illustrating a process of manufacturing the backlight unit illustrated in FIG. 2.

Referring to FIG. 6, an indium compound layer (not shown) such as indium tin oxide (ITO), indium zinc oxide (IZO), or the like is formed on the second surface B of the transparent substrate 221. The conductive wiring 601 is formed by patterning it.

Alternatively, the conductive wiring 601 may be formed by attaching a transparent electrode film using carbon nanotubes (CNT) and removing the remaining portion except for a region corresponding to the conductive wiring 601.

Meanwhile, the transparent substrate 221 may use the transparent substrate 421 illustrated in FIG. 4.

Referring to FIG. 7, the light emitting device 122 is attached to the conductive surface 601 on the second surface B of the transparent substrate 221 on which the conductive wiring 601 is formed. In this case, the light emitting device 122 may include a light emitting diode package, or a light emitting diode chip may be mounted. When the light emitting diode chip is a flip chip, bumps are attached to contact the conductive wiring 601. If the light emitting diode chip is not a flip chip, the bumps are connected to the conductive wiring 601 by wire bonding or the like.

Referring to FIG. 8, an encapsulant layer 224 is formed on the second surface B of the transparent substrate 221 to which the light emitting device 122 is attached using an encapsulant.

First, an encapsulant is coated on the second surface B of the transparent substrate 221 to form an encapsulant layer 224, and the fluorescent particles are scattered as necessary.

Thereafter, the encapsulant layer 224 is cured.

9, a reflective plate 223 is formed on the encapsulant layer 224. The reflective plate 223 may be formed by depositing a metal having good reflectance, or may be formed by attaching a separate metal plate or a metal tape.

According to the present invention, the light emitting device can be mounted opposite to the light emitting device to irradiate uniform light without increasing the thickness of the backlight unit.

In addition, since the light generated by the reversely mounted light emitting device randomly passes through the phosphor layer, uniform color coordinates and brightness can be realized.

In the detailed description of the present invention described above with reference to the preferred embodiments of the present invention, those skilled in the art or those skilled in the art having ordinary skill in the art will be described in the claims to be described later And various modifications and variations of the present invention without departing from the scope of the art. Therefore, the above description and the drawings below should be construed as illustrating the present invention, not limiting the technical spirit of the present invention.

1 is a schematic cross-sectional view of a liquid crystal display device employing a conventional backlight unit.

2 is a cross-sectional view schematically illustrating a backlight unit according to an exemplary embodiment of the present invention.

3 is a cross-sectional view schematically showing a backlight unit according to another exemplary embodiment of the present invention.

4 is a cross-sectional view schematically illustrating a backlight unit according to yet another exemplary embodiment of the present invention.

5 is a schematic cross-sectional view of a backlight unit according to still another exemplary embodiment of the present invention.

6 to 9 are perspective views illustrating a process of manufacturing the backlight unit illustrated in FIG. 2.

<Short Description of Main Drawing Numbers>

100: liquid crystal display device 110: liquid crystal display panel

111: color filter substrate 112: TFT substrate

120, 220, 320, 420, 520: backlight unit 121, 421: printed circuit board

122: light emitting element 221: transparent substrate

223: reflector plates 224, 524: encapsulant layer

601: conductive wiring

Claims (17)

A transparent substrate including a first surface for emitting light and a second surface opposite thereto; A light emitting device mounted on the second surface of the transparent substrate; And And a reflector disposed to face the second surface in order to reflect the light generated by the light emitting element toward the second surface. According to claim 1, And the transparent substrate comprises a conductive wiring patterned on the second surface to drive the light emitting device. The method of claim 2, The conductive wiring patterned on the transparent substrate comprises a transparent conductive indium compound. The method of claim 2, And a conductive wiring patterned on the transparent substrate is formed of a transparent electrode film. According to claim 1, The light emitting device is a light emitting diode package or a light emitting diode chip, characterized in that the backlight unit. The method of claim 5, The light emitting device includes a light emitting diode chip for emitting at least two different wavelengths. The method of claim 5, And a phosphor film attached to the first surface of the transparent substrate to change the light generated from the light emitting diode package or the light emitting diode chip into white light. The method of claim 5, And a fluorescent particle dispersed in the transparent substrate to change the light generated from the light emitting diode package or the light emitting diode chip into white light. The method of claim 5, An encapsulant layer is formed between the transparent substrate and the reflecting plate. The encapsulant layer is a backlight unit characterized in that the fluorescent particles for changing the light generated from the light emitting diode chip to white light is scattered. Forming a transparent conductive layer on a second surface of the transparent substrate including a first surface for emitting light and a second surface opposite thereto; Patterning the transparent conductive layer to form conductive wiring; Attaching a light emitting device to be connected to the conductive wiring; And Fixing the reflector to face the second surface. The method of claim 10, The transparent conductive layer is a backlight unit manufacturing method characterized in that it comprises an indium compound. The method of claim 10, The transparent conductive layer is a backlight unit manufacturing method, characterized in that formed by attaching a transparent electrode film on the second surface. The method of claim 10, The light emitting device is a light emitting diode package or a light emitting diode chip, characterized in that the backlight unit manufacturing method. The method of claim 13, The light emitting device includes a light emitting diode chip for emitting at least two different wavelengths. The method of claim 13, And a fluorescent particles scattered in the transparent substrate to change the light generated from the light emitting diode package or the light emitting diode chip into white light. The method of claim 10, After attaching the light emitting device, Forming an encapsulant layer by coating a transparent encapsulant on the transparent substrate to which the light emitting device is attached; And The method of claim 1, further comprising curing the encapsulant layer. The method of claim 16, And before the curing of the encapsulant layer, dispersing fluorescent particles in the encapsulant to convert light generated from the light emitting diode chip into white light.

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