KR20130026070A - Liquid crystal display device - Google Patents

Abstract

PURPOSE: A liquid crystal display device is provided to prevent a color deviation on a plurality of LEDs by implementing white light in a process that blue light emitted from the LEDs passes through a fluorescent substance film. CONSTITUTION: A fluorescent substance film is placed on a light guide plate. A photonic crystal layer(330) passing or reflecting light of a specific wavelength band and a fluorescent substance(310) are sequentially formed on the fluorescent substance film. The fluorescent substance film implements light emitted from a plurality of LEDs as white light. An optical sheet is placed on the film. A liquid crystal panel is placed on the optical sheet. [Reference numerals] (AA) White light(blue light + emitted light); (B1,B4,DD,EE) Blue light; (B2,B3) Emitted light

Description

[0001] Liquid crystal display device [0002]

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device using LED as a light source.

Liquid crystal display devices (LCDs), which are used for TVs and monitors due to their high contrast ratio and are advantageous for displaying moving images, are characterized by optical anisotropy and polarization of liquid crystals. The principle of image implementation by

Such a liquid crystal display is an essential component of a liquid crystal panel bonded through a liquid crystal layer between two side-by-side substrates, and realizes a difference in transmittance by changing an arrangement direction of liquid crystal molecules with an electric field in the liquid crystal panel. do.

However, since the liquid crystal panel does not have its own light emitting element, a separate light source is required to display the difference in transmittance as an image. To this end, a backlight unit having a light source is disposed on the back of the liquid crystal panel.

The backlight unit uses a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp, and a light emitting diode (LED) as a light source.

Among them, LEDs are particularly widely used as light sources for displays with features such as small size, low power consumption, and high reliability.

Meanwhile, a general backlight unit is classified into a direct type method and an edge type method according to the arrangement of lamps. In the edge type method, one or a pair of light sources is provided with one or two or two pairs of light guide plates. The light source has a structure in which both sides of the light guide plate are disposed, and the direct type has a structure in which several light sources are disposed below the liquid crystal panel.

Here, the direct type has a limitation in thinning, and is mainly used in a liquid crystal display device in which brightness is more important than the thickness of the screen, and the edge type which is lighter and thinner than the direct type is such as a notebook PC or a monitor PC. It is mainly used in liquid crystal displays where thickness is important.

1 is a cross-sectional view of a liquid crystal display including a backlight unit of a general edge type using an LED as a light source.

As shown in the figure, a liquid crystal display device including a general edge type backlight unit 20 includes a liquid crystal panel 10, a backlight unit 20, a support main 30, a cover bottom 50, 40).

The liquid crystal panel 10 is a part that plays a key role in image expression and is composed of first and second substrates 12 and 14 bonded to each other with a liquid crystal layer interposed therebetween.

The backlight unit 20 is provided behind the liquid crystal panel 10.

The backlight unit 20 is arranged along the length direction of at least one edge of the support main 30, and includes a plurality of LEDs 29a and a PCB 29b on which the LEDs 29a are mounted. A white or silver reflecting plate 25 mounted on the bottom 50, a light guide plate 23 mounted on the reflecting plate 25, and an optical sheet 21 positioned above the reflecting plate 25.

The liquid crystal panel 10 and the backlight unit 20 have a top cover 40 surrounding the top edge of the liquid crystal panel 10 and a back surface of the backlight unit 20 in a state where the edges are surrounded by the support main 30 having a rectangular frame shape. Cover cover 50 to cover each is coupled in front and rear are integrated through the support main 30 as a medium.

In addition, reference numerals 19a and 19b denote polarizers attached to the front and rear surfaces of the liquid crystal panel 10 to control the polarization direction of light, respectively.

Meanwhile, the LED 29a has a structure in which a phosphor (not shown) is coated on an LED chip (not shown) that emits light, and the light emitted from the LED chip (not shown) excites the phosphor (not shown). By emitting light to the outside of the LED 29a, the phosphor (not shown) plays a very important role in the LED 29a.

However, until now, in order to apply a phosphor (not shown), a method of mixing a phosphor (not shown) with silicon (not shown) and then applying a phosphor (not shown) by a dispensing method is most widely used. However, at this time, the phosphor (not shown) mixed with silicon (not shown) is a specific LED (29a) in the process of applying a phosphor (not shown) through the dispensing method to each LED (29a) by the precipitation phenomenon The problem that the amount of the phosphor (not shown) is applied in small or large amounts occurs.

That is, it is very difficult to control the amount of phosphor (not shown) applied by the LED 29a.

Therefore, the color variation of the plurality of LEDs 29a is caused by the change in the amount of phosphors (not shown).

In addition, since the phosphor 29 (not shown) is located close to the LED chip (not shown), the LED 29a deteriorates the phosphor (not shown) by heat generated when driving the LED chip (not shown). It may cause a problem of reducing the efficiency of (not shown), or deepen the degradation of the LED (29a). Therefore, the lifetime and luminous efficiency of the LED 29a are reduced.

The problem of the LED 29a causes a problem of deterioration of display quality due to uneven brightness of the liquid crystal display device using the LED 29a as a light source of the backlight unit 20.

In addition, recently, a high brightness liquid crystal display device is required, but a large amount of light emitted from the backlight unit is lost, so it is very difficult to implement a high brightness liquid crystal display device.

The present invention has been made to solve the above problems, and a first object of the present invention is to provide an improved backlight unit.

In addition, a second object of the present invention is to provide a plurality of LEDs that do not generate color deviation, and a third object of the present invention is to prevent a problem of deterioration of display quality due to uneven brightness of the liquid crystal display device.

In addition, a fourth object of the present invention is to provide a high brightness liquid crystal display device by minimizing light loss to improve the light efficiency of the liquid crystal display device.

In order to achieve the above-mentioned object, the present invention provides a liquid crystal display comprising: a light guide plate; An LED assembly arranged along a light incident surface of the light guide plate, the LED assembly including a plurality of LEDs emitting light toward the light incident surface, and a PCB on which the plurality of LEDs are mounted; A phosphor film mounted on the light guide plate, the phosphor film sequentially forming a photonic crystal layer and a phosphor for reflecting and transmitting light of a specific wavelength band; An optical sheet positioned on the phosphor film; It includes a liquid crystal panel mounted on the plurality of optical sheets, the phosphor film provides a liquid crystal display device for implementing the light emitted from the plurality of LED to white light.

In this case, the photonic crystal layer transmits the light emitted from the LED, reflects the light emitted by the phosphor, and the light emitted from the light emitted toward the photonic crystal layer is reflected, and then the optical sheet Emitted towards.

The plurality of LEDs emit blue light, and the phosphor of the phosphor film is a yellow phosphor or a phosphor mixed with red and green phosphors, and the photonic crystal layer transmits light in a wavelength range of 450 to 470 nm, and a wavelength range of 500 to 700 nm. Reflects light, and the plurality of LEDs emit UV light, the phosphors of the phosphor film are red, green, and blue tricolor phosphors, and the photonic crystal layer transmits light in a wavelength range of 100 to 400 nm or less, and 450 Reflect light in the ~ 700nm wavelength range.

In addition, the photonic crystal layer is formed of a laminated structure of thin films having different refractive indices, and the thin film includes a polymer including silicon, PET, PMMA, PC or Acryl-based resin, or silicon oxide (SiO 2) or titanium oxide (TiO 2). Made of metal oxides.

A base film is provided on one surface of the phosphor, a lenticular pattern or a prism pattern is formed on the opposite side of the base film in contact with the phosphor, and a diffusion layer is formed on the opposite side of the photonic crystal layer in contact with the phosphor.

As described above, according to the present invention, only blue light is emitted from the plurality of LEDs of the backlight unit, and a phosphor film including a phosphor and a photonic crystal layer is placed on the light guide plate, and the blue light emitted from the plurality of LEDs is phosphor. By implementing white light in the process of passing through the film, through this, there is an effect that can prevent the color deviation of a plurality of LEDs, it is possible to implement a white light with excellent light characteristics, and to improve the lifetime and luminous efficiency of the LED There is an effect to be improved.

Therefore, there is an effect that the problem of deterioration of display quality due to uneven brightness of the liquid crystal display device can be prevented from occurring.

In addition, by reflecting and reproducing the emitted light emitted to the lower side of the phosphor film by the photonic crystal layer, there is an effect that can minimize the light loss due to the emitted light, further improving the light efficiency of the backlight unit and the brightness of the liquid crystal display device It can be effected.

1 is a cross-sectional view of a liquid crystal display including a backlight unit of a general edge type method using an LED as a light source.
2 is an exploded perspective view of a liquid crystal display device according to an embodiment of the present invention.
3 is an exploded perspective view of the liquid crystal panel of FIG. 2;
4a to 4b are cross-sectional views schematically showing a phosphor film according to an embodiment of the present invention.
Figure 5 is a schematic cross-sectional view showing a traveling path of light emitted from the LED according to an embodiment of the present invention.

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

2 is an exploded perspective view of a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 3 is an exploded perspective view of the liquid crystal panel of FIG. 2.

As shown, the liquid crystal display comprises a liquid crystal panel 110, a backlight unit 120, a support main 130, a cover bottom 150, and a top cover 140.

First, the liquid crystal panel 110 will be described in more detail with reference to FIG. 3, which is an exploded perspective view of the liquid crystal panel 110. A plurality of data lines 218 are provided on one surface of the first substrate 112 called a lower substrate or an array substrate. ) And the gate line 216 cross each other to define the pixel P.

Thin film transistors T are provided at the intersections of these two lines to correspond one-to-one with the transparent pixel electrodes 220 provided in the pixel regions P. FIG.

In addition, the second substrate 114 facing the first substrate 112 with the liquid crystal layer 250 therebetween is called an upper substrate or a color filter substrate, and one surface of the first substrate 112 A grid-like black matrix 222 covering the pixel region P to expose only the pixel electrode 220 while covering non-display elements such as the data line 218, the gate line 216, and the thin film transistor T is formed. It is composed.

In addition, transparent common electrodes covering R (red), G (green), and B (blue) color filters 224 and all of them are sequentially arranged in order to correspond to the pixel areas P in the lattice. 226.

First and second polarizing plates 119a and 119b for selectively transmitting only specific light are attached to outer surfaces of the first second substrates 112 and 114, respectively.

Along the at least one edge of the liquid crystal panel 110, the gate and the data printed circuit board 117 are connected to each other via a connecting member 116 such as a flexible printed circuit board. It is flipped to the back surface of 150, and is in close contact.

Although not clearly shown in the drawings, the upper and lower alignment layers for determining the initial molecular alignment direction of the liquid crystal are interposed between the two substrates 112 and 114 and the liquid crystal layer 250. A seal pattern (not shown) is formed along the edges of both substrates 112 and 114 to prevent leakage of the liquid crystal layer 250 that is filled between the substrates 112 and 114.

Accordingly, the liquid crystal panel 110 is turned on by the thin film transistor T selected for each gate line 216 by the on / off signal of the thin film transistor T transferred to the gate line 216. When the image signal of the data line 218 is transmitted to the pixel electrode 220, the arrangement direction of the liquid crystal molecules is changed by the electric field between the pixel electrode 220 and the common electrode 226. Indicates a difference.

In the liquid crystal display device according to the present invention, a backlight unit 120 is provided for supplying light from the rear surface of the liquid crystal display panel 110 so that the difference in transmittance of the liquid crystal panel 110 is externally expressed.

The backlight unit 120 includes a white or silver reflecting plate 125, a light emitting plate 123 mounted on the LED assembly 129 and a reflecting plate 125, which are light sources arranged along a longitudinal direction of one edge thereof, and a light guide plate 123. ) Consists of a phosphor film 300 and an optical sheet 121 seated on the top.

The LED assembly 129 is a light source of the backlight unit 120 and is disposed at one side of the light guide plate 123 so as to face the light incident surface of the light guide plate 123. The LED assembly 129 includes a plurality of LEDs 129a, And a PCB 129b on which a plurality of LEDs 129a are mounted with a predetermined spacing.

At this time, the plurality of LEDs (129a) is made of a blue LED emitting blue light having a single wavelength of 450 ~ 470nm.

The light guiding plate 123 through which the light emitted from the plurality of LEDs 129a is incident is formed such that the light incident from the LED 129a travels in the light guiding plate 123 by total reflection several times, And provides a surface light source to the liquid crystal panel 110.

The light guide plate 123 is a planar shape made of a plastic material such as polymethylmethacrylate (PMMA), which is one of transparent materials capable of transmitting light, or polycarbonate (PC). (flat type) The light guide plate 123 is excellent in transparency, weather resistance, and colorability to induce light diffusion when light is transmitted.

In addition, the light guide plate 123 may include a pattern having a specific shape on the rear surface to supply a uniform surface light source. The pattern may be formed in various shapes such as an elliptical pattern, a polygon pattern, a hologram pattern, and the like in order to guide light incident into the light guide plate 123. The pattern is formed on the lower surface of the light guide plate 123 by a printing method or an injection method.

The reflector 125 is positioned on the rear surface of the light guide plate 123, and reflects light passing through the rear surface of the light guide plate 123 toward the liquid crystal panel 110 to improve the brightness of the light.

The optical sheet 121 on the light guide plate 123 includes a diffusion sheet and at least one light condensing sheet and diffuses or condenses the light passing through the light guide plate 123 to provide a more uniform surface light source to the liquid crystal panel 110 Let it enter.

In this case, the liquid crystal display of the present invention is characterized in that the phosphor film 300 is interposed between the light guide plate 123 and the optical sheet 121, and thus, the backlight unit 120 of the present invention has excellent white light. Will be implemented.

The phosphor film 300 includes a phosphor 310 (see FIG. 4A), and the light passing through the light guide plate 123 excites the phosphor 310 (see FIG. 4A) of the phosphor film 300 to form the phosphor 310 (FIG. 4A). The white light is mixed with the light emitted by the light emitted by 4a).

That is, the phosphor 310 (refer to FIG. 4A) is formed by mixing a yellow phosphor or a red (R) phosphor and a green (G) phosphor.

Therefore, when blue light is emitted from the plurality of LEDs 129a of the LED assembly 129 of the present invention, blue light is incident into the light guide plate 123 so that the blue light passes through the light guide plate 123 as a uniform surface light source.

The blue light passes through the phosphor film 300 positioned on the light guide plate 123, and the phosphor 310 is mixed with the yellow phosphor or the red (R) and green (G) phosphors of the phosphor film 300 (see FIG. 4A). It is mixed with and is realized as white light.

As described above, only blue light is emitted from the plurality of LEDs 129a, and a phosphor 310 in which a yellow phosphor or a red (R) and a green (G) phosphor are mixed on the light guide plate 123 is included. The phosphor film 300 is positioned to realize white light in the process of passing blue light emitted from the plurality of LEDs 129a through the phosphor film 300, thereby realizing white light having excellent optical characteristics.

This is because the color deviation of the plurality of LEDs 129a mounted on the PCB 129b can be prevented from occurring.

That is, the conventional LED (29a of FIG. 1) is used to apply a phosphor (not shown) on top of the LED chip (not shown) by mixing silicon (not shown) and phosphor (not shown) and then dispensing (dispensing). Therefore, it is difficult to control the amount of phosphor (not shown) applied to each LED (29a in FIG. 1) due to the precipitation phenomenon of the phosphor (not shown), and thus the phosphor (not shown) of each LED (29a in FIG. 1). There is a problem that the color deviation occurs because the amount of.

However, the LED 129a of the present invention includes a phosphor film 300 including a phosphor 310 (see FIG. 4A) in which yellow phosphors or red (R) and green (G) phosphors are mixed separately from the LED 129a. Thus, by implementing white light through this, after mixing the silicon (not shown) and the phosphor (not shown), it is not necessary to apply the phosphor (not shown) through the dispensing method, the precipitation phenomenon of the phosphor (not shown) This problem can be prevented from occurring.

In addition, in the backlight unit 120 of the present invention, the LED chip (not shown) of the LED 129a and the phosphor 310 (see FIG. 4A) are spaced apart from each other, thereby improving the lifetime and luminous efficiency of the LED 129a. .

That is, when the phosphor 310 (see FIG. 4A) and the LED chip (not shown) provided in the LED 129a are located close to each other, due to heat generated from the LED chip (not shown) when the LED 129a is driven. The phosphor 310 (see FIG. 4A) is deteriorated. When the phosphor 310 (see FIG. 4A) is deteriorated, the efficiency itself of the phosphor 310 (see FIG. 4A) is lowered, and the entire degradation of the LED 129a is caused.

In contrast, since the backlight unit 120 of the present invention is provided with a plurality of LEDs 129a and phosphors 310 (see FIG. 4A), the backlight unit 120 may be generated from an LED chip (not shown) by driving the LEDs 129a. It is possible to prevent the phosphor 310 (see FIG. 4A) from being deteriorated by heat, thereby preventing the LED 129a itself from being deteriorated. Therefore, the lifespan and luminous efficiency of the LED 129a are finally improved.

In particular, the phosphor film 300 of the present invention further includes a photonic crystal layer 330 (see FIG. 4A) on one surface of the phosphor 310 (see FIG. 4A), that is, facing the light guide plate 123. It is possible to improve the light efficiency of the 120, and finally to improve the brightness of the liquid crystal display.

That is, in the photonic crystal layer 330 (see FIG. 4A), the light efficiency of the photonic crystal layer 330 (see FIG. 4A) is excited to reproduce the emitted light.

In more detail, when blue light is incident on the yellow phosphor of the phosphor film 300 or the phosphor 310 (see FIG. 4A) in which the red (R) and green (G) phosphors are mixed, see the phosphor 310 (see FIG. 4A). ) Is excited by blue light to emit the emitted light, and the emitted light is emitted to both the upper and lower sides of the phosphor film 300, that is, the upper side facing the optical sheet 121 and the lower side facing the light guide plate 123.

At this time, the emitted light emitted to the lower side of the phosphor film 300 is not incident to the liquid crystal panel 110, so it does not have any effect in realizing the image of the liquid crystal display device is lost.

In contrast, in the liquid crystal display of the present invention, the photonic crystal layer 330 (see FIG. 4A) is formed on the phosphor film 300 so that the emitted light is reproduced, thereby minimizing light loss due to the emitted light.

Therefore, the light efficiency of the backlight unit 120 and the brightness of the liquid crystal display may be further improved. We will discuss this in more detail later.

The liquid crystal panel 110 and the backlight unit 120 are modularized through the top cover 140, the support main 130, and the cover bottom 150. The top cover 140 is the top and side surfaces of the liquid crystal panel 110. A rectangular frame having a cross section bent in a shape of “a” so as to cover an edge thereof is configured to open an entire surface of the top cover 140 to display an image implemented in the liquid crystal panel 110.

In addition, the cover bottom 150 on which the liquid crystal panel 110 and the backlight unit 120 are seated, and which is the basis for assembling the entire apparatus of the liquid crystal display device, has a horizontal surface surrounding the rear surface of the backlight unit 120 and a side at which edges thereof are vertically bent. Is done.

A support main 130 having a rectangular frame shape seated on the cover bottom 150 and surrounding the edges of the liquid crystal panel 110 and the backlight unit 120 is combined with the top cover 140 and the cover bottom 150.

The cover main body 130 may be referred to as a guide panel or a main support or a mold frame. The cover main body 130 may be referred to as a bottom cover or a bottom cover, I will.

4A to 4B are cross-sectional views schematically showing phosphor films according to embodiments of the present invention.

As illustrated, the phosphor film 300 positioned on the light guide plate 123 of FIG. 2 has a structure in which the phosphor 310 is positioned between the base film 320 and the photonic crystal layer 330.

In this case, one surface of the phosphor 310 facing in the direction facing the optical sheet (121 in FIG. 2) is defined as the upper surface, and one surface in the direction facing the light guide plate (123 in FIG. 2) is defined as the lower surface, the base film The reference numeral 320 is positioned on the upper surface of the phosphor 310 to face the optical sheet 121 (see FIG. 2), and the photonic crystal layer 330 is positioned on the lower surface of the phosphor 310 to locate the light guide plate (123 of FIG. 2). It is located facing the.

Here, the phosphor 310 is in a state in which phosphor particles are mixed with a binder. In this case, the phosphor 310 may be appropriately selected and used according to the excitation light wavelength and target emission light wavelength to be used.

That is, when the LED (129a of FIG. 2) of the backlight unit 120 of FIG. 2 is a blue LED emitting blue light, the phosphor 310 of the phosphor film 300 may be a yellow phosphor or a red (R) phosphor and a green ( G) It is made by mixing phosphors.

In this case, it is preferable to use a YAG: Ce (T3Al5O12: Ce) -based phosphor which is a yttrium (Y) aluminum (Al) garnet doped with cerium (Ce) having a wavelength of 530 to 570 nm.

The red (R) phosphor is a YOX (Y2O3: EU) series phosphor composed of a compound of yttrium oxide (Y2O3) and europium (EU) having a 611 nm wavelength, and the green (G) phosphor has a 544 nm wavelength. It is preferable to use LAP (LaPo4: Ce, Tb) series phosphors which are compounds of phosphoric acid (Po4), lanthanum (La), and terbium (Tb).

In this case, the phosphors in which the red (R) phosphor and the green (G) phosphor are mixed may use a sulfide series.

Here, the dominant wavelength is referred to as the wavelength of the red (R), green (G), and blue (B) that generates the highest luminance, the dominant wavelength of the phosphor 310.

In addition, the base film 320 positioned on the phosphor 310 may include a transparent acrylic resin, polymethylmethacrylate (PMMA), polyethylene terephthalate (PET), silicon oxide (SiO 2), or titanium oxide (TiO 2), which is a thermoplastic resin. It may be made of an inorganic material such as aluminum or an aluminum (Al) material having a thickness of 20 nm or less.

The base film 320 is formed with a lenticular or prism pattern 321 on the other side of the base film 320 opposite to the one surface in contact with the phosphor 310.

Since the lenticular or prism patterns 321 are arranged adjacent to each other in a band shape, a plurality of patterns 321 having a shape of repeating mountains and valleys are arranged to protrude from the base film 320 in a row, thereby passing through the phosphor 310. The white light passes through the phosphor film 300 and condenses the light toward the optical sheet (121 of FIG. 2).

In addition, as the white light implemented by the phosphor 310 is partially diffused in the process of passing through the base film 320, the color difference may be prevented from occurring according to the viewing angle of the white light implemented through the phosphor film 300. have.

The photonic crystal layer 330 disposed below the phosphor 310 has a polarizer having a predetermined polarization axis in a stacked structure of thin films having different refractive indices, and the photonic crystal layer 330 has a relatively low refractive index. It may be made of silicon oxide (SiO 2) having and titanium oxide (TiO 2) having a relatively high refractive index.

In addition, it may be made of polymethylmethacrylate (PMMA), polyethylene terephthalate (PET), a thermoplastic resin, and the like.

As a result, the photonic crystal layer 330 has a selective reflection characteristic reflecting only light having a specific wavelength among the incident light.

Particularly, in the photonic crystal layer 330 of the present invention, only light in the wavelength range of 500 to 700 nm, which is the yellow (Y), red (R), and green (G) wavelengths of visible light, is reflected, and 450 to the blue (B) wavelength band of the visible light is reflected. The light in the 470 nm wavelength band is allowed to transmit.

In this case, the reflection zone and the transmission zone of the photonic crystal layer 330 may be selected by adjusting the refractive index and the number of layers of each layer.

Accordingly, the photonic crystal layer 330 of the present invention passes the blue light emitted from the blue LED (129a of FIG. 2), and the emitted light emitted by the phosphor 310 by the blue light does not pass through and is reflected.

As a result, by allowing the emitted light to be reproduced, it is possible to minimize the light loss due to the emitted light. Therefore, the light efficiency of the backlight unit 120 (in FIG. 2) and the brightness of the liquid crystal display device can be further improved.

That is, blue light, which is the phosphor 310 excitation light emitted from the LED (129a of FIG. 2), passes through the photonic crystal layer 330, enters the phosphor 310, and excites the phosphor 310 to form emission light. The light emitted from the upper side toward the optical sheet (121 of FIG. 2) of the phosphor film 300 is mixed with the blue light while passing through the base film 320 of the phosphor film 300 to be realized as white light.

The white light realized by transmitting the phosphor film 300 is processed to high quality while passing through the optical sheet 121 (see FIG. 2), and then enters the liquid crystal panel 110 (FIG. 2).

In addition, the emitted light emitted toward the lower side of the phosphor film 300 toward the light guide plate 123 of FIG. 2 is reflected and reproduced by the photonic crystal layer 330, and thus emitted to the upper side of the phosphor film 300.

Therefore, the regenerated emitted light is also mixed with blue light to implement white light.

Therefore, the liquid crystal display device of the present invention can minimize the light loss due to the emitted light, thereby improving the light efficiency of the backlight unit (120 of FIG. 2) and the brightness of the liquid crystal display device.

In this case, the diffusion layer 340 may be further formed on the other side of the photonic crystal layer 330 on the opposite side of the surface of the photonic crystal layer 330 to prevent the light incident on the phosphor film 300 from being partially concentrated.

The diffusion layer 300 may include a light diffusion component such as beads (not shown) therein or may form a fine pattern (not shown) on the lower surface of the photonic crystal layer 330.

The phosphor film 300 may be formed through a lamination process in which the phosphor 310 is interposed between the base film 320 and the photonic crystal layer 330 and then pressed by a laminator.

5 is a cross-sectional view schematically showing a traveling path of light emitted from an LED according to an embodiment of the present invention.

As illustrated, the LED assembly 129 and the light guide plate provided on the reflecting plate 125, the light guide plate 123, and one side surface of the light guide plate 123 and include a plurality of LEDs 129a and PCB 129b. The phosphor film 300 and the optical sheet 121 are stacked on the upper portion 123 to form a backlight unit (120 of FIG. 2).

In addition, the liquid crystal panel 110 including the liquid crystal layer 250 between the first and second substrates 112 and 114 and the backlight unit 120 and the upper portion thereof is positioned. On each of the outer surfaces of the first substrates 112 and 114, polarizing plates 119a and 119b for selectively transmitting only specific light are attached.

Blue light is emitted from the plurality of LEDs 129a of the LED assembly 129, and the emitted blue light F is incident into the light guide plate 123 through the light incident surface of the light guide plate 123.

In addition, the blue light F incident into the light guide plate 123 spreads evenly to a wide area of the light guide plate 123 while traveling in the light guide plate 123 by a plurality of total reflections in the light guide plate 123, and toward the phosphor film 300. It is emitted.

The blue light F emitted toward the phosphor film 300 is mixed with the emitted light emitted by the phosphor (310 of FIG. 4B) in the course of passing through the phosphor film 300, thereby realizing white light (W).

That is, the blue light F emitted from the LED 129a passes through the photonic crystal layer 330 of the phosphor film 300 to excite the yellow phosphor or the red (R) phosphor and the green (G) phosphor, and the yellow phosphor or Among the emitted light emitted by the red (R) phosphor and the green (G) phosphor, the emitted light and the blue light (F) emitted to the upper side of the phosphor film 300 are mixed to implement the white light (W).

At this time, the emitted light emitted to the lower side of the phosphor film 300 of the emitted light is reflected by the photonic crystal layer 330, and is emitted to the upper side of the phosphor film 300, and the emitted light is also mixed with the blue light (F) Thus, the white light W is realized.

The white light W implemented by transmitting the phosphor film 300 is emitted toward the optical sheet 121, processed into high quality while passing through the optical sheet 121, and then incident to the liquid crystal panel 110. Through this, the liquid crystal panel 110 may display an image of high brightness.

Therefore, the liquid crystal display of the present invention allows only the blue light F to be emitted from the plurality of LEDs 129a, and the yellow phosphor or the red (R) phosphor and the green (G) phosphor on the light guide plate 123 (FIG. 4B). By placing the phosphor film 300 comprising a 310 of the white light, so that the white light (W) is implemented in the process of passing the blue light (F) emitted from the plurality of LEDs (129a) through the phosphor film 300, The color deviation of the LED 129a may be prevented from occurring, and thus, the white light W having excellent optical characteristics may be realized, and the lifespan and luminous efficiency of the LED 129a may be improved.

Therefore, it is possible to prevent the problem of deterioration of display quality due to uneven brightness of the liquid crystal display device.

In particular, the phosphor film 300 includes a photonic crystal layer 330 that reflects light of a specific wavelength band, thereby emitting light emitted to the lower side of the phosphor film 300 among the light emitted by the phosphor (310 of FIG. 4B). By allowing the light to be reflected toward the upper side of the phosphor film 300, the light loss due to the emitted light can be minimized, thereby improving the light efficiency of the backlight unit (120 of FIG. 2) and the brightness of the liquid crystal display device.

On the other hand, in the above description and the accompanying drawings, the blue LED (129a) is emitted as a light source of the backlight unit (120 of FIG. 2) as an example, the present invention is a UV LED having a short wavelength of 100 ~ 400nm It is also applicable.

In this case, when the UVLED is used, the phosphor (310 in FIG. 4B) of the phosphor film 300 is composed of three color phosphors of red (R), green (G), and blue (B), wherein red (R) and green (G) ), Desired white light can be realized by adjusting the mixing ratio of the blue (B) phosphor.

Here, the red (R) phosphor is a YOX (Y2O3: EU) series phosphor composed of a compound of yttrium oxide (Y2O3) and europium (EU) having a 611 nm wavelength, and the green (G) phosphor mainly has a 544 nm wavelength. It is preferable to use LAP (LaPo4: Ce, Tb) series phosphors which are compounds of phosphoric acid (Po4), lanthanum (La), and terbium (Tb).

In this case, the phosphors in which the red (R) phosphor and the green (G) phosphor are mixed may use a sulfide series.

The blue (B) phosphor uses barium (Ba), magnesium (Mg), aluminum oxide-based materials, and BAM blue (BaMgAl10O17: EU) -based phosphors, which are compounds of europium (EU), whose wavelength is 450 nm. It is desirable to.

In addition, the blue (B) phosphor may be a silicate series.

In addition, the photonic crystal layer 330 of the phosphor film 300 allows all light in the visible wavelength range not to be transmitted and is reflected, and only UV having a wavelength band of 100 to 400 nm is transmitted, thereby minimizing light loss due to the emitted light. can do.

In addition, the LED assembly 129 has been described as a side light (side light) method is located on one side of the light guide plate 123, but the direct type (array type) to arrange a plurality of LED assembly 129 side by side on top of the reflector (125) direct type), and in the case of the direct type, the light guide plate 123 may be omitted.

The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

310: phosphor,
320: base film,
330 photonic crystal layer
340: diffusion layer

Claims (9)

A light guide plate;
An LED assembly arranged along a light incident surface of the light guide plate, the LED assembly including a plurality of LEDs emitting light toward the light incident surface, and a PCB on which the plurality of LEDs are mounted;
A phosphor film mounted on the light guide plate, the phosphor film sequentially forming a photonic crystal layer and a phosphor for reflecting and transmitting light of a specific wavelength band;
An optical sheet positioned on the phosphor film;
And a liquid crystal panel
Includes, wherein the phosphor film is a liquid crystal display device for implementing the light emitted from the plurality of LED to white light.
The method of claim 1,
And the photonic crystal layer transmits the light emitted from the LED and reflects the emitted light emitted by the phosphor.
The method of claim 2,
The light emitting light emitted toward the photonic crystal layer among the emitted light is reflected, and then emitted toward the optical sheet.
The method of claim 2,
The plurality of LEDs emit blue light, and the phosphor of the phosphor film is a phosphor in which yellow phosphors or red and green phosphors are mixed. Reflecting liquid crystal display device.
The method of claim 2,
The plurality of LEDs emit UV light, and the phosphors of the phosphor film are red, green, and blue tricolor phosphors, and the photonic crystal layer transmits light in a wavelength range of 100 to 400 nm or less, and light in a wavelength of 450 to 700 nm. Reflective liquid crystal display device.
The method of claim 1,
And the photonic crystal layer has a stacked structure of thin films having different refractive indices.
The method according to claim 6,
The thin film is a liquid crystal display device comprising a metal oxide containing a silicon oxide (SiO2), titanium oxide (TiO2) or a polymer containing PET, PMMA, PC or Acryl series resin.
The method of claim 1,
A base film is provided on one surface of the phosphor, and a lenticular pattern or a prism pattern is formed on the opposite side of the base film in contact with the phosphor.
The method of claim 1,
And a diffusion layer is formed on the opposite side of the photonic crystal layer in contact with the phosphor.

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