KR20140079687A - Liquid Crystal Display Device - Google Patents

Abstract

A liquid crystal display device according to the present invention includes a liquid crystal panel and a backlight unit disposed under the liquid crystal panel to emit white light to the liquid crystal panel. The liquid crystal panel includes a first substrate and a second substrate opposite to each other; a liquid crystal layer formed between the first and second substrates; and a red color filter, a green color filter, and a blue color filter formed on a surface of the first substrate. A spectrum peak wavelength of light transmitting the green color filter is 510 to 530nm band, and a full width at half maximum (FWHM) has the range of 60 to 70nm. The present invention has high color reproduction characteristic using white light by designing the spectrum peak wavelength of light transmitting the green color filter with the range of 510 to 530nm band, and the FWHM with the range of 60 to 70nm.

Description

[0001] The present invention relates to a liquid crystal display device,

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device having excellent color reproducibility.

Liquid crystal display devices have a wide variety of applications ranging from notebook computers, monitors, spacecrafts and aircraft to the advantages of low power consumption and low power consumption and being portable.

The liquid crystal display device includes a lower substrate, an upper substrate, and a liquid crystal layer formed between the two substrates. The arrangement of the liquid crystal layers is adjusted according to whether an electric field is applied or not, .

Hereinafter, a conventional liquid crystal display device will be described with reference to the drawings.

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

As shown in FIG. 1, the conventional liquid crystal display device includes a liquid crystal panel 10 and a backlight unit 20.

The liquid crystal panel 10 includes an upper substrate 11 and a lower substrate 12.

On the upper substrate 11, a light-shielding layer and a color filter layer are formed although not shown. The light-shielding layer is formed in a matrix structure to prevent light from leaking to a region other than the pixel. The color filter layer is formed in a region between the light shielding layers of the matrix structure, and includes a red color filter, a green color filter, and a blue color filter.

Though not shown, a thin film transistor, a pixel electrode, and a common electrode are formed on the lower substrate 12. The thin film transistor is formed in each pixel as a switching element. The pixel electrode is connected to the thin film transistor. The common electrode is arranged in parallel to the pixel electrode so as to form a horizontal electric field together with the pixel electrode.

A liquid crystal layer is formed between the upper substrate 11 and the lower substrate 12, though not shown.

The backlight unit 20 includes a light source 21, a light guide plate 22, a reflection plate 23, and an optical sheet 24.

The light source 21 is disposed on a side surface of the light guide plate 22 and emits light to a side surface of the light guide plate 22.

The light guide plate 22 guides the light emitted from the light source 21 toward the liquid crystal panel 10. To change the light path, the light guide plate 22 is provided with a pattern of embossed or engraved .

The reflection plate 23 is disposed under the light guide plate 22 and reflects light traveling under the light guide plate 22 to reduce light loss.

The optical sheet 24 serves to uniformly transmit the light guided by the light guide plate 22 to the liquid crystal panel 10, and is formed of a combination of a plurality of sheets.

Such a conventional liquid crystal display device uses a combination of a red (R) LED lamp, a green (G) LED lamp, and a blue (B) LED lamp as the light source 21 so as to have high color reproducibility have.

When the LED lamp of red (R), green (G), and blue (B) is used as the light source 21, light incident on the liquid crystal panel 10 has an independent wavelength spectrum, High color reproducibility can be achieved.

However, such conventional liquid crystal display devices have the following problems.

The LED lamps of red (R), green (G), and blue (B) have a problem that the brightness or chromaticity easily changes due to the temperature change of the driving module of the liquid crystal display device or the temperature rise of the LED lamp itself immediately after lighting.

FIG. 2 is a graph showing the luminous efficiency of conventional red (R), green (G) and blue (B) LED lamps according to temperature changes. As can be seen from FIG. 2, the luminous efficiency of the LED lamp is lowered as the temperature rises.

On the other hand, in order to solve the above problems, a cooling system for preventing the temperature rise of the LED lamp itself or an optical compensation circuit should be additionally applied. In this case, the manufacturing method becomes complicated and the material cost rises.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal display device having high color reproducibility while using white light whose brightness and chromaticity do not change easily.

In order to achieve the above object, the present invention provides a liquid crystal display device comprising a liquid crystal panel and a backlight unit positioned below the liquid crystal panel and emitting white light to the liquid crystal panel, wherein the liquid crystal panel comprises: A second substrate; A liquid crystal layer formed between the first substrate and the second substrate; And a red color filter, a green color filter, and a blue color filter formed on one surface of the first substrate, wherein the spectrum peak wavelength of the light transmitted through the green color filter is 510 to 530 nm, and the full width at Half Maximum (FWHM) is 60 to 70 nm.

According to the present invention as described above, the following effects can be obtained.

According to the present invention, by designing the spectrum peak wavelength of the light transmitted through the green color filter to be in the range of 510 to 530 nm and the full width at half maximum (FWHM) of 60 to 70 nm, .

1 is a schematic cross-sectional view of a conventional liquid crystal display device.
FIG. 2 is a graph showing the luminous efficiency of conventional red (R), green (G) and blue (B) LED lamps according to temperature changes.
3 is a schematic cross-sectional view of a liquid crystal display device according to an embodiment of the present invention.
FIG. 4A is a graph showing a transmittance spectrum of a color filter according to an exemplary embodiment of the present invention, FIG. 4B is a graph illustrating a transmittance spectrum of a green color filter and a transmittance spectrum of a conventional green color filter according to an embodiment of the present invention Graph.
5 is a graph showing the emission spectrum of a white LED lamp according to the present invention and the emission spectrum of a conventional white LED lamp.
6 is a schematic cross-sectional view of a white LED lamp according to an embodiment of the present invention.
7 is a schematic cross-sectional view of a white LED lamp according to another embodiment of the present invention.

The term "on " as used herein is meant to encompass not only the case where a configuration is formed directly on top or bottom of another configuration, but also the case where a third configuration is interposed between these configurations.

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

3 is a schematic cross-sectional view of a liquid crystal display device according to an embodiment of the present invention.

As shown in FIG. 3, the liquid crystal display according to an embodiment of the present invention includes a liquid crystal panel 100 and a backlight unit 200.

The liquid crystal panel 100 includes a first substrate 110, a second substrate 120, a liquid crystal layer 130, and a sealant 140.

More specifically, a light shielding layer 111 and a color filter layer 116 are formed on one surface of the first substrate 100 facing the liquid crystal layer 130 on one surface of the first substrate 110.

The light shielding layer 111 is formed in a matrix structure on the first substrate 110 to prevent leakage of light to regions other than the pixels.

The color filter layer 116 is formed in the light shielding layer region of the matrix structure, that is, in the individual pixel region. Such a color filter layer 116 includes a red (R) color filter 113, a green (G) color filter 114 and a blue (B) color filter 115.

The transmittance characteristics of the red (R) color filter 113, the green (G) color filter 114 and the blue (B) color filter 115 will be described with reference to FIGS. 4A and 4B.

FIG. 4A is a graph showing a transmittance spectrum of a color filter according to an exemplary embodiment of the present invention, FIG. 4B is a graph illustrating a transmittance spectrum of a green color filter and a transmittance spectrum of a conventional green color filter according to an embodiment of the present invention Graph.

4A, according to an embodiment of the present invention, the spectrum peak wavelength of the light transmitted through the blue (B) color filter is 445 to 455 nm, the full width at half maximum (FWHM) Is 85 to 95 nm. The spectrum peak of the light transmitted through the green (G) color filter is in the range of 510 to 530 nm, and the full width at half maximum (FWHM) is 60 to 70 nm. In addition, the light transmitted through the red (R) color filter has a maximum transmittance at a wavelength of 600 nm or more, and the maximum transmittance is kept relatively constant.

The Full Width at Half Maximum (FWHM) means a peak width at half the spectral peak value of light.

4B, the spectrum of the light transmitted through the green (G) color filter according to an embodiment of the present invention has a maximum transmittance lower than that of the light passing through the conventional green (G) color filter, but the spectrum width Become narrower. Therefore, the light transmitted through the green (G) color filter according to an embodiment of the present invention becomes relatively dark green light as compared with the conventional one.

The red (R) color filter 113 and the blue (B) color filter 115 having the transmittance spectral characteristics according to an embodiment of the present invention can use various conventionally known red and blue color filter materials have.

However, the green (G) color filter 114 having the transmittance spectral characteristics according to an embodiment of the present invention may use a metal complex salt azo methine organic pigment as a primary color.

Particularly, the green (G) color filter 114 is formed by using the metal complex salt azo methine organic pigment (green pigment) as a main color and the yellow pigment as an auxiliary color, And the spectrum peak wavelength and full width at half maximum (FWHM) of the light may be changed according to the mixing ratio.

The mixing ratio is preferably 7: 3 to 5: 5, more preferably 6: 4, between the green pigment of the main color and the yellow pigment of the auxiliary color.

The yellow pigment may be a compound represented by the following general formula (1) or (2), but is not limited thereto.

Formula 1

(2)

Referring again to FIG. 3, an overcoat layer may be further formed on the color filter layer 116, although not shown. The overcoat layer serves to planarize the surface of the first substrate 110.

A thin film transistor layer 121 is formed on one surface of the second substrate 120 facing the liquid crystal layer 130 and the thin film transistor layer 121 A pixel electrode 122 and a common electrode 123 for adjusting the alignment direction of the liquid crystal layer 130 are formed.

Though not specifically shown, a gate line, a data line, and a thin film transistor are formed in the thin film transistor layer 121.

The gate line and the data line are arranged to intersect with each other to define a pixel region, and the thin film transistor is connected to the gate line and the data line within the pixel region, respectively. Such a thin film transistor includes a gate electrode, a semiconductor layer, a source electrode, and a drain electrode.

The thin film transistor may be variously modified in various forms known in the art. For example, the gate electrode may be formed as a top gate structure located on the semiconductor layer, or the gate electrode may be formed as a bottom gate structure located below the semiconductor layer.

The pixel electrode 122 and the common electrode 123 form an electric field therebetween, and the alignment direction of the liquid crystal layer 130 is adjusted by such an electric field. The pixel electrode 122 is connected to the thin film transistor.

The formation of the pixel electrode 122 and the common electrode 123 for adjusting the alignment direction of the liquid crystal layer 130 may be variously changed depending on the driving method of the liquid crystal.

For example, in the IPS (In-Plane Switching) mode and the FFS (Fringe Field Switching) mode, by forming both the pixel electrode 122 and the common electrode 123 on the thin film transistor layer 121 of the second substrate 120 A horizontal electric field is formed between the pixel electrode 122 and the common electrode 123 and the alignment direction of the liquid crystal layer 130 is controlled by the horizontal electric field.

In the TN (Twisted Nematic) mode and VA (Vertical Alignment) mode, the pixel electrode 122 is formed on the thin film transistor layer 121 of the second substrate 120 and the color filter layer 116 A vertical electric field is formed between the pixel electrode 122 and the common electrode 123 and the alignment direction of the liquid crystal layer is adjusted by the vertical electric field.

The liquid crystal display device according to the present invention can be applied to various driving methods as described above. In accordance with each driving method, the liquid crystal display device according to the present invention may have various configurations known in the art such as a configuration on the first substrate 110 and the second substrate 120 Can be changed.

The liquid crystal layer 130 is formed between the first substrate 110 and the second substrate 120 and the sealant 140 is formed between the first substrate 110 and the second substrate 120 Thereby bonding the first substrate 110 and the second substrate 120 to each other.

The backlight unit 200 is positioned below the liquid crystal panel 100 and emits white light to the liquid crystal panel 100. The backlight unit 200 includes an LED lamp 210, a light guide plate 220, a reflection plate 230, and an optical sheet 240.

The LED lamp 210 is mounted on a printed circuit board 218. The LED lamp 210 is disposed on the side surface of the light guide plate 220 and emits light to the side surface of the light guide plate 220.

The LED lamp 210 emits white light. The specific configuration and optical spectrum characteristics of the LED lamp 210 will be described later with reference to FIGS. 5 to 7. FIG.

The light guide plate 220 guides the light emitted from the LED lamp 210 toward the liquid crystal panel 100. The light guide plate 220 is provided with a relief pattern or a relief pattern on its surface in order to change the light path. The pattern provided on the light guide plate 220 may be formed in various patterns known in the art.

The reflection plate 230 is disposed under the light guide plate 220 to reduce light loss by reflecting light traveling under the light guide plate 220.

The optical sheet 240 uniformly transmits the light guided by the light guide plate 220 toward the liquid crystal panel 100. The optical sheet 240 may be a combination of a diffusion sheet and a prism sheet, but is not limited thereto.

5 is a graph showing the emission spectrum of a white LED lamp according to the present invention and the emission spectrum of a conventional white LED lamp.

As can be seen from FIG. 5, the white LED lamp according to the first and second embodiments of the present invention shows a clearer emission peak in green and red than the conventional white LED lamp.

That is, the white LED lamp according to the present invention realizes independent wavelength spectrum for each color group. More specifically, the white LED lamp according to the present invention has a green peak wavelength range in the 520 to 530 nm band, and a red peak wavelength range in the 650 to 660 nm band.

The white LED light according to the present invention can be realized by a combination of a blue light emitting diode chip, a green phosphor and a red phosphor, as shown in FIGS. 6 and 7, which will be described later.

The green phosphor has a green peak wavelength range in the 520 to 530 nm band and the red phosphor has a red peak wavelength range in the 650 to 660 nm band. The green phosphor has a full width at half maximum (FWHM) of 30 to 50 nm.

The green phosphor includes a phosphor of a silicate type or a nitride type. Green phosphors of the silicate (Silicate) type M ₂ SiO _4: Eu ²⁺ can include: it contains Eu ^{2 +,} the green phosphor of the nitride (Nitride) type CaSiN.

The red phosphor includes a phosphor of a nitride type. The red phosphor of the nitride (Nitride) type is CaAlSiN _3: Eu may include a ^{2 +.}

In FIG. 5, the first embodiment includes the green phosphor of the silicate type and the red phosphor of the nitride type, and the second embodiment includes the green phosphor of the nitride type and the red phosphor of the nitride type. .

The white LED lamp according to the present invention may have a structure in which a light emitting diode chip is mounted on a printed circuit board or a structure in which a light emitting diode chip is mounted on a package (Package on Board: POB structure) mounted on a printed circuit board.

6 is a schematic cross-sectional view of a white LED lamp according to an embodiment of the present invention, which corresponds to a COB structure.

6, the white LED lamp 210 according to the embodiment of the present invention is mounted on the printed circuit board 218. [

The white LED lamp 210 includes a first electrode pattern 211a and a second electrode pattern 211b, a light emitting diode chip 212, a protective film 213, a molding portion 214, and a silk ring 215 .

The first electrode pattern 211a and the second electrode pattern 211b are formed on the printed circuit board 218 and are connected to the LED chip 212, respectively.

The light emitting diode chip 212 is formed on the first electrode pattern 211a and is connected to the first electrode pattern 211a and the second electrode pattern 211b by a conductive wire W .

The light emitting diode chip 212 includes an active layer that functions as a light emitting layer, and the active layer emits blue light. As the active layer for emitting blue light, various materials known in the art can be used.

The protective layer 213 is formed on the light emitting diode chip 212 and the conductive wire W to protect the light emitting diode chip 212 and the conductive wire W. [

The molding part 214 is formed on the protective film 213 and is made of a mixture of a green phosphor, a red phosphor and a transparent resin.

Accordingly, the blue light emitted from the light emitting diode chip 212 is transmitted through the green phosphor and the red phosphor constituting the molding part 214 and finally emitted as white light.

The silk ring 215 allows the protective film 213 and the molding part 214 to be maintained in a dome shape.

As described above, the LED lamp 210 according to one embodiment of the present invention is formed by combining the active layer for emitting blue light constituting the LED chip 212 and the green phosphor and the red phosphor constituting the molding part 214 Thereby having the emission spectrum as shown in Fig. 5 described above.

7 is a schematic cross-sectional view of a white LED lamp according to another embodiment of the present invention, which corresponds to a POB structure.

As shown in FIG. 7, the white LED lamp 210 according to another embodiment of the present invention is mounted on the printed circuit board 218.

The white LED lamp 210 includes a first electrode pattern 211a and a second electrode pattern 211b, a light emitting diode chip 212, a supporting portion 219, and a molding portion 214.

The white LED lamp 210 is mounted on the printed circuit board 218 through connection electrodes 216a and 216b and solders 217a and 217b.

A first connection electrode 216a and a second connection electrode 216b are formed on the printed circuit board 218 and connected to an external power source. The first connection electrode 216a is formed with a first solder 217a And a second solder 217b is formed on the second connection electrode 216b.

The first solder 217a is connected to the first electrode pattern 211a and the second solder 217b is connected to the second electrode pattern 211b.

A light emitting diode chip 212 is formed on the first electrode pattern 211a and the light emitting diode chip 212 is electrically connected to the first electrode pattern 211a and the second electrode pattern 211b by a wire W. [ Lt; / RTI >

The light emitting diode chip 212 includes an active layer that functions as a light emitting layer, and the active layer emits blue light. As the active layer for emitting blue light, various materials known in the art can be used.

The support portion 219 serves to support the first electrode pattern 211a and the second electrode pattern 211b. The support portion 219 has an opening for the molding portion 214.

The molding part 214 is formed in the opening part on the LED chip 212 and is made of a mixture of a green phosphor, a red phosphor and a transparent resin.

Accordingly, the blue light emitted from the LED chip 212 is transmitted through the green phosphor and the red phosphor constituting the molding part 214 and finally emitted as white light.

The green phosphor and the red phosphor include a phosphor of a silicate series or a nitride series.

100: liquid crystal panel 110: first substrate
111: Shading layer 113: Red color filter
114: green color filter 115: blue color filter
116: Color filter layer 120: Second substrate
121: thin film transistor layer 122: pixel electrode
123: common electrode 130: liquid crystal layer
140: Sealant 200: Backlight unit
210: LED lamp 220: light guide plate
230: reflector 240: optical sheet

Claims (10)

And a backlight unit disposed below the liquid crystal panel and emitting white light to the liquid crystal panel,
In the liquid crystal panel,
A first substrate and a second substrate facing each other;
A liquid crystal layer formed between the first substrate and the second substrate; And
And a red color filter, a green color filter, and a blue color filter formed on one surface of the first substrate,
Wherein the spectral peak wavelength of the light transmitted through the green color filter is 510 to 530 nm and the full width at half maximum (FWHM) is 60 to 70 nm. The method according to claim 1,
Wherein the green color filter comprises a metal complex salt azo methine organic pigment. 3. The method of claim 2,
Wherein the green color filter further comprises a yellow pigment. The method of claim 3,
The yellow pigment may be represented by the following general formula (1) or (2)
Formula 1

(2)

Lt; RTI ID = 0.0 > 1, < / RTI > The method according to claim 1,
Wherein the backlight unit includes an LED lamp that emits white light. 6. The method of claim 5,
Wherein the LED lamp has a green peak wavelength range in a 520 to 530 nm band and a red peak wavelength range in a 650 to 660 nm band. 6. The method of claim 5,
Wherein the LED lamp comprises a blue light emitting diode chip, a green phosphor, and a red phosphor. 8. The method of claim 7,
Wherein the green phosphor has a peak wavelength range in the 520 to 530 nm band and the red phosphor has a peak wavelength range in the 650 to 660 nm band. 8. The method of claim 7,
The green phosphor may include a phosphor of a silicate type or a nitride type,
Wherein the red phosphor comprises a nitride type nitride phosphor. 10. The method of claim 9,
Green phosphors of the silicate (Silicate) type M ₂ SiO _4: Green phosphor of the type, comprising a Eu ^{2 +} the nitride (Nitride) is CaSiN:, contains Eu ^{2 +} of the nitride (Nitride) type And the red phosphor includes CaAlSiN ₃ : Eu ^{2 +} .

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