KR20100115469A - Optical filter for display device and display device having the same - Google Patents

Abstract

PURPOSE: The optical filter for the display device and display device including the same reduces the color deviation according to the viewing angle increase. CONSTITUTION: The orange wavelength area absorbing material and cyanogen wavelength area absorbing material are mixed in the material and the optical filter is formed. The optical filter comprises the first thick film(860), and the thin film layer(820) and the second thick film(840). In the center of the optical filter, the thin film layer is formed.

Description

Optical filter for display device and display device having the same {OPTICAL FILTER FOR DISPLAY DEVICE AND DISPLAY DEVICE HAVING THE SAME}

The present invention relates to an optical filter for a display device and a display device having the same. More particularly, the present invention provides an optical filter for a display device that provides excellent image quality by improving color reproduction and reducing color deviation due to an increase in viewing angle. It relates to a display device.

As the modern society is highly informationized, image display-related components and devices have been remarkably advanced and widespread. Among them, display apparatuses for displaying images are widely used for television apparatuses, monitor apparatuses of personal computers, and the like, and are being enlarged and thinned.

In general, a liquid crystal display (LCD) is a flat panel display device that displays an image using liquid crystal, and is thinner and lighter than other display devices, and has a low driving voltage and low power consumption. It is widely used throughout the industry.

1 is a conceptual diagram conceptually showing the basic structure and driving principle of an LCD.

For example, the conventional VA mode LCD is attached so that the optical axes of the two polarizing films 110 and 120 are perpendicular to each other. The liquid crystal molecules 150 exhibiting birefringence are inserted and arranged between the two transparent substrates 130 coated with the transparent electrode 140. When the electric field is applied by the driving power supply unit 180, the liquid crystal molecules are arranged to move perpendicular to the electric field.

The light emitted from the backlight unit becomes linearly polarized light after passing through the first polarizing film 120. When the light is off, as shown in the left side of FIG. 1, the liquid crystal is vertically aligned with respect to the substrate. Is maintained as it is so as not to pass through the second polarizing film 110 perpendicular to the first polarizing film 120.

However, in the on state, as shown on the right side of FIG. 1, the liquid crystal is horizontally oriented between the optical axes of the two orthogonal polarizing films 110 and 120 in a direction parallel to the substrate by an electric field, thereby linearly polarizing through the first polarizing film. The light passes through the second polarizing film by changing to a linearly polarized, circularly or elliptically polarized state in which the polarization state is rotated 90 degrees immediately before reaching the second polarizing film while passing through the liquid crystal molecules. By adjusting the intensity of the electric field, the alignment angle of the liquid crystal is gradually changed from the vertical alignment to the horizontal direction, and the intensity of light emitted from the liquid crystal can be adjusted.

2 is a conceptual diagram illustrating alignment states and light transmittances of liquid crystals according to viewing angles.

When the liquid crystal molecules are arranged in a predetermined direction in the pixel 220, the arrangement state is different depending on the viewing angle.

When viewed from the front side in the right direction 210, the arrangement state of the liquid crystal molecules is almost seen in the horizontal orientation 212, the screen is relatively bright. When viewed from the front of the screen 230, the arrangement state of the liquid crystal molecules 232 looks the same as the arrangement of liquid crystal molecules in the pixel 220. When viewed from the front in the left direction 250, the arrangement state of the liquid crystal molecules appears in the vertical alignment 252, and the screen appears relatively dark.

Therefore, the LCD generates light intensity and color change according to the change in the viewing angle, and the viewing angle is greatly limited compared to the self-luminous display. Therefore, much research has been conducted for improving the viewing angle.

3 is a conceptual diagram illustrating an example of the related art for improving the contrast ratio change and the color change according to a change in viewing angle.

Referring to FIG. 3, the pixel is divided into two partial pixels, that is, the first pixel portion 320 and the second pixel portion 340 so that the liquid crystal arrangement of each pixel portion is symmetrical to each other. According to the viewing direction, the arrangement of the liquid crystals in the first pixel unit 320 and the arrangement of the liquid crystals in the second pixel unit 340 are simultaneously seen, and the intensity of light visible to the viewer is determined by the light of each pixel unit. It is the sum of the strengths of.

That is, when viewed from the front side in the right direction 310, the liquid crystal of the first pixel portion 320 is shown as the horizontal alignment 312 and the liquid crystal of the second pixel portion 340 is shown as the vertical alignment 314. The screen may be made bright by the one pixel unit 320. Similarly, when viewed from the front in the left direction 350, the liquid crystal of the first pixel portion 320 is shown in the vertical alignment 352, and the liquid crystal of the second pixel portion 340 is shown in the horizontal alignment 354. By the two pixel unit 340, the screen can be seen brightly. When viewed from the front (330) is the same as the arrangement state of each pixel portion. Accordingly, the brightness of the screen when viewed by the viewer becomes the same or similar as the viewing angle changes, and becomes symmetric about the vertical direction with respect to the screen. Therefore, the change in contrast ratio and the degree of color change according to the change of viewing angle can be improved.

4 is a conceptual diagram illustrating another example of the related art for improving the change in contrast ratio and color change according to a change in viewing angle.

Referring to FIG. 4, an optical film 420 having a birefringence characteristic, the characteristic of which is the same as that of the liquid crystal molecules in the pixel 440 in the LCD panel, and which is symmetric with the arrangement state of the liquid crystal molecules, is added. Due to the arrangement state of the liquid crystal in the pixel 440 and the birefringence characteristic of the optical film 420 according to the viewing direction, the light intensity seen by the viewer is the sum of the light intensities.

That is, when viewed from the front to the right direction 410, the liquid crystal in the pixel 440 is shown in the horizontal alignment 414, the virtual liquid crystal by the optical film 420 is shown in the vertical alignment 412, the light intensity is Each sum. Similarly, when viewed from the front in the left direction 450, the liquid crystal in the pixel 440 is shown in the vertical alignment 454 and the virtual liquid crystal by the optical film 420 is shown in the horizontal alignment 452, the light intensity is Each sum. In the front view 430, the arrangement state of the liquid crystal molecules in the pixel 440 and the birefringent arrangement state of the optical film 420 appear to be the same (432 and 434).

As a result, the change in contrast ratio and color change due to the change of viewing angle is improved, but the luminance and color change according to the viewing angle remain a problem to be solved.

On the other hand, the LCD includes a display panel and a backlight unit, which are currently commercialized as a light source of the backlight unit are a cold cathode fluorescent lamp (CCFL) and a light emitting diode (LED).

5 is a view comparing color gamut of LCD using LED backlight, LCD using CCFL backlight and NTSC in CIE 1976 UCS color coordinate. In addition, FIG. 6 is a view showing color deviations in the horizontal and vertical viewing angles in an LCD using an LED backlight, and FIG. 7 is a view showing the color deviations in the horizontal and vertical viewing angles in an LCD using a CCFL backlight.

Compared with CCFL, LED has superior color reproduction power as shown in FIG. 5, and as shown in FIGS. 6 and 7, there is an advantage of showing better image quality due to less color shift with increasing viewing angle. However, LED has a disadvantage that the price is very expensive, so CCFL is still used as a backlight unit for general LCD products except for high-priced LCD TVs.

Therefore, in the LCD device using a low-cost CCFL, there is a need for a technique for reducing color shift due to the increase in the color reproduction power and viewing angle close to the LED level.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a color shift improving optical filter that can improve color reproducibility and, in particular, reduce color shift due to an increase in viewing angle to show more improved image quality characteristics.

In addition, an object of the present invention is to provide a display device having the optical filter for the display device.

In order to achieve the above object, the present invention is an optical filter for a display device used in a display device, and absorbs 570 ~ 600nm orange wavelength region and 480 ~ 510nm cyan wavelength region of the transmitted light, the display image according to the viewing angle It provides an optical filter for a display device, characterized in that to compensate for the color deviation of.

The optical filter may include a light absorption pattern, and the light absorption pattern may absorb a green wavelength region of 510 nm to 560 nm.

The optical filter may be any one of an antireflection film, a protective film, a diffusion film, a light guide plate, a prism sheet, and a polarizing film.

The optical filter may include an adhesive layer including an orange wavelength region absorbing material absorbing an orange wavelength region of 570 to 600 nm and a cyan wavelength region absorbing substance absorbing a cyan wavelength region of 480 to 510 nm.

In the optical filter, a first thick film layer, a thin film layer, and a second thick film layer are sequentially stacked, and the thin film layer has a thickness of 780 nm or less, and the first thick film layer and the second thick film layer have a thicker thickness than the thin film layer. And at least one of the first thick film layer, the thin film layer, and the second thick film layer includes an orange wavelength region absorbing material absorbing an orange wavelength region of 570 to 600 nm and a cyan wavelength region absorbing substance absorbing a cyan wavelength region of 480 to 510 nm. can do.

The present invention also provides a display device comprising the optical filter for display device.

Preferably, the display device is a liquid crystal display device using a cold cathode fluorescent lamp (CCFL) as a light source.

According to the above configuration, the present invention can provide excellent image quality characteristics by improving the color reproduction power and in particular by reducing the color shift according to the increased viewing angle, it is possible to achieve a cost-performance improvement.

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

The present invention utilizes the following technical principles.

8 is a view showing the emission spectrum of the LED, Figure 9 is a view showing the emission spectrum of the CCFL.

The superiority of LEDs in improving color reproduction area and reducing color shift can be seen by comparing the emission spectra of LEDs and CCFLs.

In the case of LED, the emission spectrum of narrow shape is shown around B (~ 450nm), G (~ 540nm), and R (~ 640nm). On the other hand, in the CCFL, B is 420-500 nm wide and there are three emission peaks. R is 570-630 nm wide and there are two emission peaks. Here, peaks in the cyan wavelength region of 480 to 510 nm and the orange wavelength region of 570 to 600 nm are the main causes of deterioration of color reproduction power and color shift.

Therefore, color reproduction and color shift can be improved by converting the emission spectrum of the CCFL into a narrow emission spectrum such as an LED using a dye capable of absorbing the wavelength range.

Based on the above principle, color deviation of the display image may be compensated for by increasing the viewing angle by absorbing the orange wavelength region and the cyan wavelength region of the light passing through the optical filter.

To this end, an optical filter in which the orange wavelength region absorbing material and the cyan wavelength region absorbing material are dispersed or dissolved in a base material may be attached or disposed in front of the backlight unit or in front of the display panel to improve color reproduction and color shift. have.

10 is a view showing an optical filter according to a first embodiment of the present invention.

In FIG. 10, the optical filter 11 of a single layer structure is shown.

The optical filter is formed by mixing an orange wavelength region absorbent material and a cyan wavelength region absorbent material on a base material.

As the substrate, a substrate made of a transparent resin material such as PET, UV resin, or the like may be used.

FIG. 11 is a spectral absorption curve obtained by measuring the absorption of the optical filter of FIG. 10 under a D65 light source. FIG.

Irrespective of the thickness of the optical filter of FIG. 10 and the contents of the orange wavelength region absorbing material and the cyan wavelength region absorbing material, the absorption peak and its full width at half maximum (FWHM) exist in a specific wavelength region and are always constant. The definition of the full width at half maximum means the width when the peak is halfway between the maximum and minimum values.

Under the D65 light source, when the absorptivity of the optical filter of FIG. 10 was measured, the half width of the maximum peak of 380 nm to 550 nm was between 440 to 520 nm, and the half width of the maximum peak of 550 to 780 nm was between 570 to 615 nm. desirable.

12 is a spectral radiation normalization curve of an LCD TV having the optical filter of FIG.

After mounting the optical filter of FIG. 10 on an LCD TV using CCFL as a light source, a spectral radiation curve was obtained on a full white screen, and a spectral radiation normalization curve was obtained through a normalization process divided by the maximum value of each spectral radiation curve. .

When comparing the normalized spectral radiation curves before and after applying the optical filter, it is desirable that the maximum peaks existing at 480-500 nm and 580-600 nm decrease by 30% or more. That is, the optical filter of this invention lowers a cyan wavelength range peak and an orange wavelength range peak.

As a result of applying the optical filter of the present invention to the LCD TV, the color reproducibility was improved by 8% from 70% to 78%.

13 is a view showing an optical filter according to a second embodiment of the present invention.

When the light emitted from the display panel is emitted at a high gradation, as the viewing angle increases, the luminance decreases in all wavelength regions and the blue wavelength region decreases relatively quickly. Such color change can be minimized by using a structure of a thick film layer, a thin film layer, and a thick film layer.

The optical filter of FIG. 13 includes a first thick film layer 860, a thin film layer 820, and a second thick film layer 840, and at least one of them includes an orange wavelength region absorbing material and a cyan wavelength region absorbing material. Can be.

The thin film layer 820 is formed in the center of the optical filter, and the first thick film layer 860 and the second thick film layer 840 are formed on both surfaces of the thin film layer 820.

The thickness of the thin film layer 820 is less than or equal to the wavelength range of visible light. Therefore, the thickness of the thin film layer 820 is 780 nm or less. This is because when the thickness of the thin film layer 820 is greater than 780 nm, constructive and destructive interference does not occur in the visible light region.

Meanwhile, the first thick film layer 860 and the second thick film layer 840 are larger than the thin film layer 820. Accordingly, the thicknesses of the thick film layers 860 and 840 may be greater than 780 nm and may reach several mm, for example 5 mm. The thicknesses of the first thick film layer 860 and the second thick film layer 840 may be the same or may be different.

The thin film layer 820 has a first refractive index, the first thick film layer 860 has a second refractive index, and the second thick film layer 840 has a third refractive index. The first refractive index may be lower or higher than the second refractive index and the third refractive index.

The laminate may be manufactured by forming a thin film layer having a low refractive index between the thick film layers having a high refractive index. For example, the refractive index of the first thick film layer 860 and the second thick film layer 840 may be 2 to 4, and the refractive index of the thin film layer may be 1 to 2.

On the contrary, a high refractive index thin film layer may be formed between the low refractive index thick layers. In this case, glass may be used as at least one of the thick film layers. In the case of tempered glass, since the refractive index is about 1.5, when tempered glass is used as the transparent substrate, the transparent substrate may be used as the low refractive thick film layer.

In addition to the transparent substrate, an adhesive layer or an air layer may also be used as the thick film layer. In addition, an antireflection film, an anti-fog film, or a functional film may also be used as the thick film layer.

As such, in order to adjust the transmittance and reflectance of the light, the refractive indices of the first thick film layer, the second thick film layer, and the thin film layer may be variously modified.

The refractive index of the thin film layer 820 is n, and the refractive indices of the first thick film layer 860 and the second thick film layer 840 are n _t . For convenience, it is assumed that the refractive indices of the first thick film layer 860 and the second thick film layer 840 are the same, but are not limited thereto.

The first thick film layer 860 is formed on the panel side, and the second thick film layer 840 is formed on the viewer side. Incident and refraction angles of light incident on the first thick film layer 860 satisfy the following conditions according to Snell's law.

n _t sinθ _t = n _O sinθ _O

The thin film layer incident light 880 incident from the panel is partially transmitted while refracting and partially reflected by the difference in refractive index at the interface between the first thick film layer 860 and the thin film layer 820.

The angle formed between the normal to the interface and the incident light 880 is θ _t , and the angle formed by the transmitted light 881 inside the thin film layer that is refracted and transmitted into the thin film layer is θ.

The transmitted light 881 into the thin film layer is a thin film layer transmitted light 882 that is partially refracted at the interface between the thin film layer 820 and the second thick film layer 840 while passing through the second thick film layer. Becomes the internal reflected light 883 of the thin film layer.

In this case, an angle between the thin film layer transmitted light 882 and the normal to the interface between the thin film layer 820 and the second thick film layer 840 is determined by the difference in refractive index between the thin film layer 820 and the second thick film layer 840. . Assuming that the refractive indices of the first thick film layer 860 and the second thick film layer 840 are the same, the angle formed by the thin film layer transmitted light 882 with the normal to the interface between the thin film layer 820 and the second thick film layer 840 is θ _t .

The angle θ _t is the angle (θ _o) and the refractive index of the thick film layer n _t, the refractive index of the air incident on the incident light (889) from the panel, the optical filter as shown in Equation 1 by the Snell's law (snell) n _O (= 1).

Incident light (889) transmitted from each of the end panels the light emitted by the passing through the optical filter is the same as the incident angle θ _O by Snell's law, the end angle θ _O is available for the viewers to see a viewing angle.

The reflectance at each interface is as shown in Equations 2 and 3 below. Here, R _p is a reflectance when p-polarized light is reflected and R _s is a s polarized light is reflected.

R _p = [(n _t cosθ-ncosθt) / (n _t cosθ + ncosθt)] ²

R _s = [(ncosθ-n _t cosθ _t ) / (ncosθ + n _t cosθ _t )] ²

It can be seen that the reflectances R _p and R _s are changed by the refractive indices (n, n _t ), the incident angle (θ _t ) and the refractive angle (θ) of the thin film layer and the thick film layer, respectively.

In Equation 4, the reflectance R is an average of R _p of Equation 2 and R _s of Equation 3 below.

The internal reflected light 883 of the thin film layer is transmitted while being partially refracted at the interface to become the thin film layer reflected light 887, and part of the reflected light becomes the internal reflected light 884 of the thin film layer, and this process is repeated.

To the transmittance T in the expression (4) is the sum of a transmittance T ₂ by a transmitted light transmissivity T ₁ and the thin film layer 885 by a thin film layer transmitting light (882). Although only two refractive lights are shown in FIG. 13, reflection and refraction continue to occur repeatedly at the interface, and the total transmittance by these refractive lights is the total transmittance T. FIG.

To the sum of a reflectivity R ₂ by a reflected light reflectivity R ₁ and the thin film layer (888) by the reflectance of the reflected light R is also the thin film layer (887) at the interface from the equation (4). Similarly, although only two reflected light are shown in FIG. 13, the total reflectance R by all the reflected light reflected from the interface is the total reflectance R.

In the process of multi-reflecting light by two interfaces by the first thick film layer 860, the thin film layer 820, and the second thick film layer 840, the transmittance may be changed depending on the wavelength due to interference. .

In the white light having a high gradation level, in order to reduce the color deviation caused by the increase in the viewing angle, the thickness ( l ) of the thin film layer such that the average value of the transmittance (T) according to Equation 4 is maximized for the light in the blue wavelength region, The refractive index n of the thin film layer and the reflectance R at the interface between the first thick film layer and the thin film layer are adjusted.

^{T = (1 - R) 2} / (1 + R 2 - 2Rcosδ)

Here, the phase difference δ of the thin film layer transmitted lights 882 and 885 is expressed by Equation 5 below.

δ = (2π / λ) 2n l cosθ (0 ° ≤ θ ≤ 80 °)

δ is determined by the refractive index n, the thickness l , the refractive angle θ, and the wavelength λ of the thin film layer 820. Depending on the phase difference, constructive interference may occur, and destructive interference may occur. The maximum transmittance is reached when the optical path length difference between each of the thin film layer transmitted lights 882 and 885 is an integer multiple of the wavelength.

The phase difference δ is determined when the refractive index n, the thickness l and the refractive angle θ of the thin film layer are determined for a specific wavelength range. Here, the refractive angle θ is a value that is automatically determined when the refractive indices n and n _t and the viewing angle θ _O of the thin film layer and the thick film layer are determined.

It can be seen from the equations (1) to (3) that the reflectance varies depending on the refractive indices (n, n _t ) and the viewing angle (θ _O ) of the thin film layer and the thick layer. Therefore, the reflectance can be determined by adjusting the refractive indices n and n _t of the thin film layer and the thick film layer with respect to the specific viewing angle θ _O.

As shown in Equation 4, the transmittance T is determined when the reflectance R and the phase difference δ are determined. Therefore, by selecting the refractive index (n, n _t ) and the thickness ( l ) of the thin film layer and the thick film layer it is possible to control the transmittance for light of a specific viewing angle and a specific wavelength.

For example, the thickness of the thin film layer may be selected to be 780 nm or less, and the refractive index of the thin film layer may be determined in the range of 1 to 2, and the refractive index of the thick layer may be in the range of 2 to 4, thereby increasing the transmittance of light in a specific wavelength region in a large viewing angle range. Will be. Alternatively, the same effect can be obtained when the refractive index of the thin film layer is 2 to 4, the refractive index of the thick film layer is 1 to 2, and the refractive index of the thin film layer is higher than that of the thick film layer.

As such, multi-beam interference may compensate for a characteristic in which the intensity of light decreases relatively in the blue wavelength region as the viewing angle increases. That is, when the viewing angle is in the range of approximately 80 degrees, constructive interference occurs in the blue wavelength region to increase the transmittance, and offset interference occurs in the green and red wavelength regions to decrease the transmittance, thereby allowing light in all wavelength regions even when the viewing angle is large. The intensity reduction rate of is equal to or similar to compensate for the imbalance in the blue region. The laminate of the thick film layer, the thin film layer and the thick film layer of FIG. 13 is effective in reducing the color deviation caused by the increase in the viewing angle of the white light having a high gray level.

The thick film layer / thin film layer / the thick film layer laminate is a ratio of the minimum transmittance to the maximum transmittance in the wavelength range of the entire visible light region of 380 to 780 nm is 0.5 to 0.9.

14 is a view showing an optical filter according to a third embodiment of the present invention.

On the other hand, when the light emitted from the display panel is emitted at a low gray scale, as the viewing angle increases, the luminance increases in all wavelength regions and the green wavelength region increases relatively quickly.

Therefore, the light emitted from the display panel gradually increases the absorption of light in the entire wavelength region as the viewing angle increases, and in particular, the absorption of light in the green wavelength region of 510 nm to 560 nm is relatively increased so that the color of the viewing angle increases. The deviation can be minimized.

As shown, the optical filter of FIG. 14 has a structure in which a light absorption pattern 13 is formed on one surface of a background 12.

The background 12 may be formed by mixing an orange wavelength region absorbent material and a cyan wavelength region absorbent material on a transparent resin substrate.

The substrate can be basically used as long as it has a high transparency through which light can be transmitted and a material capable of forming the light absorption pattern 13, but is lightweight, easy to handle, and easy to use in polyester, acrylic, One or more selected from the group consisting of cellulose, polyolefin, polyvinyl chloride, polycarbonate, phenol, and urethane may be used. Among them, polyesters and polycarbonates having a good balance of heat resistance and flexibility are preferred, and biaxially stretched polyesters and polycarbonates are more preferred.

The recessed groove of the background 12 may be formed through a process such as roll imprinting, extrusion molding, injection molding, or the like.

The light absorption pattern 13 may include a green wavelength range absorbing material that absorbs a green wavelength range of 510 nm to 560 nm. In addition, it may include an orange wavelength region absorbing material and a cyan wavelength region absorbing material.

For example, the light absorption pattern 13 may be formed by filling a concave groove of the background 12 with a resin in which a green wavelength region absorbing material or the like is mixed.

An optical filter in which the light absorption pattern was filled with the green wavelength region absorbing material was mounted on an LCD TV, and the color coordinates of the front and the viewing angle were 60 degrees on a full white screen.

When the green wavelength region absorbing material is filled in the wedge cross-section light absorption pattern, as the viewing angle increases, the color of the green wavelength region absorbing material becomes stronger, and the color coordinates move from the u ', v' chromaticity diagram to the pink region. In addition, when the carbon black or cyan wavelength absorber and the orange wavelength absorber are filled together with the green wavelength absorber, the color coordinate is shifted from the u ', v' chromaticity diagram to the Purplish Pink region.

u ', v' chromaticity diagram in Δv '/ Δu', i.e. (v _'60 - _{v '0) / (u'} 60 - that the u 'a value of _{0) tan (-15 °) ~} tan (45 °) is preferred.

Specifically, in the case where only the green wavelength-absorbing material is filled in the light absorption pattern, the slope of the color coordinate change when the viewing angle is 60 degrees in front of the u ', v' chromaticity diagram is 20 to 45 degrees. When the carbon black is filled together, the slope of the color coordinate change when the viewing angle is 60 degrees relative to the front is -15 to 15 degrees, and when the green wavelength region absorbing material, the cyan wavelength region absorbing material, and the orange wavelength region absorbing material are filled together, It is preferable that the inclination of the color coordinate change when the viewing angle is 60 degrees relative to the front is -15 to 15 degrees.

The light absorption pattern 13 may have various shapes such as a stripe pattern, a wave pattern, a matrix pattern, a honeycomb pattern, and the like, when viewed from the front. Also, for example, even in the case of a stripe pattern, it may be arranged in various directions such as a horizontal stripe, a vertical stripe, an inclined stripe, and the like.

Meanwhile, as illustrated in FIG. 14, the light absorption pattern 13 may have a wedge pattern, a square pattern, and the like. Also in the case of a wedge pattern, for example, it may be formed on the back of the background 12 and its bottom face may face the display panel, on the contrary, may be formed on the front of the background 12 and its bottom face may face the viewer. Various modifications are possible, such as may be formed on both sides of (12).

15 is a view showing an optical filter according to the fourth embodiment of the present invention.

The optical filter of FIG. 15 has a backing 14 supporting the background 12. FIG. 15 shows that the orange wavelength region absorbing material and the cyan wavelength region absorbing material may be included in the backing 14 instead of the background 12 of FIG. 14.

The backing 14 may be manufactured by mixing an orange wavelength range absorbing material and a cyan wavelength range absorbing material to a resin base material.

10 to 15 illustrate optical filters that perform only a color shift improving function. However, the present invention is not limited to this. The optical filter of the present invention may have a function other than color shift improvement.

For example, as shown in FIG. 16, the optical filter of the present invention may include other functional layers, transparent substrates, and the like in addition to the single layer or multilayer films of FIGS. 10 to 15.

In FIG. 16, the antireflection film 16 is adhered to the entire surface of the transparent substrate 15 made of glass, and the optical filter is formed by adhering the film 11 of FIG. 10 to the rear surface.

As another embodiment, the optical filter of the present invention may be an antireflection film, a protective film, a diffusion film, a light guide plate, a prism sheet, and a polarizing film. Since the technical configuration of these functional films is already known, the detailed description is omitted.

For example, by mixing the orange wavelength range absorbing material and the cyan wavelength range absorbing material in a backing base material of the antireflection film, color reproduction and color shift can be improved in addition to performing an antireflection function. .

As another embodiment, the optical filter of the present invention may be an optical filter having at least one of the functional film. That is, in addition to the functional film, other functional films, transparent substrates, and the like may be provided.

As another embodiment, the optical filter of the present invention may include an adhesive layer and include an orange wavelength region absorbing material and a cyan wavelength region absorbing material in the adhesive layer. The adhesive layer is used for the purpose of adhesion of each functional film.

The orange wavelength range absorbing material and the cyan wavelength range absorbing material are sufficient to be included in the optical filter of the present invention, and are not necessarily included in any one film. For example, the orange wavelength range absorbing material and the cyan wavelength range absorbing material may be included in different films constituting the optical filter. In addition, the optical filter of the present invention does not necessarily need to be integrally formed. For example, the optical filter of the present invention may be composed of a plurality of parts formed spaced apart from each other, and furthermore, the parts may be formed at the front and the rear of the display panel, respectively. For example, the orange wavelength range absorbing material may be included in the color correction layer in front of the display panel, and the cyan wavelength range absorbing material may be included in the prism sheet behind the display panel.

17 illustrates a display device according to a sixth embodiment of the present invention.

As shown in FIG. 17, the display device of FIG. 17 includes a liquid crystal display panel 100 and a backlight unit 900, and the optical filter of the present invention includes a liquid crystal display panel 100 and a backlight of the liquid crystal display panel 100. May be disposed between the units 900.

Up to now, for convenience of description, the optical filter of the present invention is illustrated as being used in a liquid crystal display device using a CCFL backlight unit as a light source, but is not necessarily limited thereto. Unless contrary to the technical idea of the present invention, the optical filter of the present invention may be applied to various other display devices.

1 is a conceptual diagram conceptually showing the basic structure and driving principle of an LCD.

2 is a conceptual diagram illustrating alignment states and light transmittances of liquid crystals according to viewing angles.

3 is a conceptual diagram illustrating an example of the prior art for improving the contrast ratio change and color deviation according to the viewing angle.

4 is a conceptual diagram illustrating another example of the related art for improving the contrast ratio and color deviation according to the viewing angle.

5 is a view comparing color gamut of LCD using LED backlight, LCD using CCFL backlight and NTSC in CIE 1976 UCS color coordinate.

6 is a view showing color deviation according to the viewing angle in the horizontal and vertical direction in the LCD using the LED backlight.

7 is a view showing color deviation according to the viewing angle in the horizontal and vertical directions in the LCD using a CCFL backlight.

8 is a view showing an emission spectrum of the LED.

9 shows the emission spectrum of CCFLs.

10 is a view showing an optical filter according to a first embodiment of the present invention.

FIG. 11 is a spectral absorption curve obtained by measuring the absorption of the optical filter of FIG. 10 under a D65 light source. FIG.

12 is a spectral radiation normalization curve showing the normalization power of an LCD TV with the optical filter of FIG. 10.

13 to 16 illustrate optical filters according to the second to fifth embodiments of the present invention.

17 illustrates a display device according to a sixth embodiment of the present invention.

Claims (16)

An optical filter for display device used in a display device, An optical filter for a display device, comprising: absorbing 480-510 nm cyan wavelength region and 570-600 nm orange wavelength region of transmitted light to compensate for color deviation of a display image according to a viewing angle. The method of claim 1, An optical filter for display device, characterized in that the half peak width of the maximum peak of 380 ~ 550nm is between 440 ~ 520nm, and the half peak width of the maximum peak of 550 ~ 780nm is between 570 ~ 615nm. The method of claim 1, An optical filter for display device, characterized in that the spectral radiation normalization curve reduces the maximum peak present at 480 to 500 nm and 580 to 600 nm by 30% or more. The method of claim 1, An optical filter for display device, comprising a cyan wavelength region absorbing material absorbing a cyan wavelength region of 480 ~ 510nm and an orange wavelength region absorbing material absorbing an orange wavelength region of 570 ~ 600nm. The method of claim 4, wherein And the orange wavelength region absorbing material and the cyan wavelength region absorbing material are present in a mixed state on a resin substrate. The method of claim 4, wherein And the orange wavelength region absorbing material and the cyan wavelength region absorbing material are included in different layers. The different layers are provided in the front and rear of the display panel are spaced apart from each other provided for the optical filter. The method of claim 1, The optical filter has a light absorption pattern, The light absorption pattern is an optical filter for a display device, characterized in that for absorbing the green wavelength region of 510 ~ 560nm. The method of claim 8, The light absorption pattern, along with the green wavelength region absorbing material absorbing the green wavelength region of 510 ~ 560nm, and the cyan wavelength region absorbing material absorbing the cyan wavelength region of 480 ~ 510nm and orange wavelength region of 570 ~ 600nm An optical filter for display device, comprising an orange wavelength range absorbing material. The method of claim 8, The light absorption pattern, the optical filter for a display device comprising a carbon black with a green wavelength region absorbing material for absorbing the green wavelength region of 510 ~ 560nm. The method of claim 8, The light absorption pattern is a wedge section-stripe pattern, wedge section-wavy pattern, wedge section-matrix pattern, wedge section-honeycomb pattern, rectangle section-stripe pattern, rectangle section-wave pattern, rectangle section-matrix pattern or rectangle section -An optical filter for display device, characterized by having a honeycomb pattern. The method of claim 1, The optical filter is one of an antireflection film, a protective film, a diffusion film, a light guide plate, a prism sheet, and a polarizing film. The method of claim 1, The optical filter may include an adhesive layer including at least one of an orange wavelength region absorbing material absorbing an orange wavelength region of 570 to 600 nm and a cyan wavelength region absorbing substance absorbing a cyan wavelength region of 480 to 510 nm. Optical filter for display device. The method of claim 1, The optical filter, the first thick film layer, the thin film layer and the second thick film layer is sequentially stacked, The thin film layer has a thickness of 780nm or less, the first thick film layer and the second thick film layer has a thickness thicker than the thin film layer, At least one of the first thick film layer, the thin film layer, and the second thick film layer includes at least one of an orange wavelength absorbing material absorbing an orange wavelength region of 570-600 nm and a cyan wavelength absorbing material absorbing a cyan wavelength region of 480-510 nm. Optical filter for display device comprising a. A display device comprising the optical filter for display device according to claim 1. The method of claim 15, The display apparatus is a liquid crystal display using a cold cathode fluorescent lamp (CCFL) as a light source.

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