KR101221469B1 - Color compensation optical film for display device and optical filter for display device having the same - Google Patents

Abstract

The present invention is a substrate that transmits light; It provides a color compensation film for a display device formed on the substrate comprising a color light absorption pattern for absorbing light in the green wavelength region, orange wavelength region and cyan wavelength region. Preferably, the color light absorption pattern is formed by including a green wavelength region absorbent material, an orange wavelength region absorbent material, and a cyan wavelength absorbent material in an ultraviolet curable resin. Preferably, the green wavelength region absorbing material is a pink pigment that absorbs light in the wavelength range of 510 to 560 nm. In addition, the present invention provides an optical filter for a display device comprising the color compensation film for the display device.

Description

COLOR COMPENSATION OPTICAL FILM FOR DISPLAY DEVICE AND OPTICAL FILTER FOR DISPLAY DEVICE HAVING THE SAME}

The present invention relates to an optical filter for a display device, and more particularly, to a color compensation film for a display device and a display filter optical filter including the same, which can minimize mixed color variation due to an increased viewing angle.

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 is a flat panel display 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. Taking a conventional VA mode LCD as an example, the optical axes of the two polarizing films 110 and 120 are attached to be 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.

Meanwhile, 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, and thus linearly polarized 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 appears to be almost horizontally aligned 212, and the screen appears 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. As a result, 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.

FIG. 5 is a graph illustrating a result of measuring a spectral change by emitting white light at a full gray scale level according to an increase in a viewing angle of an LCD according to the prior art to which the methods of FIGS. 3 and 4 are simultaneously applied.

As shown in FIG. 5, the intensity of the spectrum gradually decreases as the viewing angle increases. In order to accurately investigate the degree of reduction for each wavelength region, normalization is performed by dividing the maximum value of each spectrum as shown in FIG. 6.

As shown in FIG. 6, it can be seen that as the viewing angle increases, the intensity of the normalized spectrum decreases in the blue region of 400 to 500 nm while the other wavelength region is the same. This shows that the light in the blue region of 400 to 500 nm decreases in intensity of the spectrum as the viewing angle increases compared to other wavelength regions. Therefore, as the viewing angle increases, the white state becomes yellow, which is a complementary color of blue, and the image quality is degraded due to this color change.

An object of the present invention is to provide a color compensation film and an optical filter for a display device that can minimize the color change in the mixed color when the viewing angle is increased to secure the viewing angle of the display device and improve the image quality.

Another object of the present invention is to minimize the color change of the red (Red) mixed color (Sony Red, Moderate Red, etc.) and Blue series mixed color (Sony Blue, Purple, Purplish Blue, etc.) when the viewing angle increases To provide a color compensation film and an optical filter for a display device that can minimize the change.

Technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above object, the present invention is a substrate for transmitting light; It provides a color compensation film for a display device formed on the substrate comprising a color light absorption pattern for absorbing light in the green wavelength region, orange wavelength region and cyan wavelength region.

Preferably, the color light absorption pattern is formed by including a green wavelength region absorbent material, an orange wavelength region absorbent material, and a cyan wavelength absorbent material in an ultraviolet curable resin.

Preferably, the green wavelength region absorbing material is a pink pigment that absorbs light in the wavelength range of 510 to 560 nm.

In addition, the present invention provides an optical filter for a display device comprising the color compensation film for the display device.

According to the above configuration, the color compensation film and optical filter for the display device of the present invention forms a color light absorption pattern filled with a color light absorbing material on one surface of the substrate, and when the viewing angle increases, the red series mixed color (Sony Red, Moderate Red) Etc.) and Blue series mixed colors (Sony Blue, Purple, Purplish Blue, etc.) can be minimized to minimize the color change in the mixed colors, thereby securing the viewing angle of the display device and improving the image quality have.

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

[Thick film, thin film, thick film type color compensation film]

7 is a cross-sectional view showing an optical filter for a display device according to a contrasting embodiment for checking with the present invention.

The optical filter 700 includes a transparent substrate 720 and a color compensation film 740. In addition, the optical filter of FIG. 7 includes an antireflective film 760, in place of or in addition to this, various other functional films may be provided. The stacking order of FIG. 7 may be variously modified.

The color compensation film 740 includes a first thick film layer 744, a thin film layer 742, and a second thick film layer 746. The thin film layer 724 is formed between the first thick film layer 744 and the second thick film layer 746. The thickness of the thin film layer 724 is smaller than or equal to the wavelength range of visible light. Therefore, the thickness of the thin film layer 724 is 780 nm or less. This is because when the thickness of the thin film layer 724 is greater than 780 nm, constructive and destructive interference does not occur in the visible light region.

Meanwhile, the first thick film layer 744 and the second thick film layer 746 are larger in thickness than the thin film layer 724. Therefore, the thicknesses of the thick film layers 744 and 746 may be greater than 780 nm and may reach 5 mm. The thicknesses of the first thick layer 744 and the second thick layer 746 may be the same or may be different.

The thin film layer 724 has a first refractive index, the first thick film layer 744 has a second refractive index, and the second thick film layer 746 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 color compensation film 740 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 indexes of the first thick film layer 744 and the second thick film layer 746 may be 2 to 4, and the refractive index of the thin film layer 742 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. Since the refractive index of the tempered glass is approximately 1.5, when the tempered glass is used as the transparent substrate, the second thick film layer formed in contact with the transparent substrate may be omitted in the configuration of the optical filter.

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.

Hereinafter, a process of reflecting and transmitting light in the color compensation film will be described with reference to FIG. 8.

FIG. 8 is a conceptual diagram illustrating reflection and transmission of light in the color compensation film of FIG. 7.

The thin film layer 820 is formed in the center of the color compensation film 800, 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 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 . In the present contrasting embodiment, 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.

An angle formed by the normal to the interface and the incident light 880 is θ _t , and an 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. . In the contrasting embodiment, since the refractive indices of the first thick film layer 860 and the second thick film layer 840 are the same, the thin film layer transmitted light 882 has a normal to the interface between the thin film layer 820 and the second thick film layer 840. The angle formed is θ _t .

The angle θ _t is an angle θ _{o at} which incident light 889 from the panel is incident on the color compensation film according to Equation 1 according to Snell's law, the refractive index n _t of the thick film layer, and the refractive index n of air. _It can be represented using _O (= 1).

Incident light (889) from the panel are transmitted through the color compensation film for transmitting each of the finally emitted light are equal to the incident angle θ _O by Snell's law, the angle θ eventually _O corresponds to a field of view the viewer sees.

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-ncosθ _t ) / (n _t cosθ + ncosθ _t )] 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 below, 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. 8, 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 lights are shown in FIG. 8, the total reflectance R by all the reflected lights 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 color compensation film for a display device of FIG. 8, the thickness l of the thin film layer l is such that the average value of the transmittance T according to Equation 4 is maximum for light in a blue region having a wavelength λ of 380 to 500 nm. 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 ≤ 60 °)

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 ) of the thin film layer and the thick film layer and the thickness ( l ) of the thin 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 described above, as the viewing angle increases by using the multi-beam interference, a characteristic in which the intensity of light decreases relatively in the blue wavelength region (380 to 500 nm) may be compensated. 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. By using the color compensation film for the display device as described above it is possible to minimize the color change according to the change in viewing angle.

Hereinafter, a result of measuring the transmittance by attaching an optical filter for a display device including a color compensation film for a display device to the front of the LCD panel will be described.

As illustrated in FIG. 7, the color compensation film 740 is designed by forming a thin film layer 742 between the first thick film layer 744 and the second thick film layer 746. The refractive index of the first thick film layer 744 and the second thick film layer 746 is 2.5, the thickness is 1 mm, the refractive index of the thin film layer 742 is 1.5, and the thickness is 190 nm.

9 is a graph showing transmittance according to a change in viewing angle of the color compensation film 740. As the viewing angle increases, the transmittance increases in some areas of the blue wavelength (380 nm to 460 nm), and the transmittance decreases in some areas of the green and red wavelengths (540 nm to 780 nm). Therefore, as described above, by reducing the sudden spectral reduction rate occurring in the blue wavelength region with increasing viewing angle, and increasing the spectral reduction rate in the green and red wavelength regions, the reduction ratio of the spectrum due to the viewing angle increase in the entire visible wavelength region is the same to It can be adjusted to be similar.

The color compensation film 740 has 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. That is, as shown in FIG. 9, when the maximum transmittance is 1 in the entire wavelength region, the minimum transmittance is approximately 0.8.

10 shows a change in normalized spectrum with increasing viewing angle of the color compensation film 740. It can be seen that the rate of decrease of the spectrum as the viewing angle increases in the entire wavelength region as well as the blue region is almost the same. This shows that the color change almost disappeared with increasing viewing angle.

FIG. 11 is a graph of change (Δu′v ′) of color coordinates (CIE 1976 L u′v ′) with increasing viewing angle. In the graph, the horizontal axis represents a horizontal angle, that is, a viewing angle. It can be seen from FIG. 11 that the amount of color change when the color compensation film is present is significantly reduced compared to the case where the color compensation film is not present.

[Color Light Absorption Pattern Type Color Compensation Film]

The color compensation film described above compensates for the relative decrease in luminance in the 380 nm to 500 nm region where the luminance decreases relatively while passing through the liquid crystal as the viewing angle increases, thereby increasing the maximum gray scale level according to the increase in the viewing angle of the liquid crystal display panel. It is possible to reduce the color change of white light. However, this may not minimize the color change due to the change in the viewing angle in the case of all colors.

In fact, when the LCD device implements an image or a video, various colors are implemented in addition to white, so satisfying the reduction of color change for the LCD device plays an important role in securing a viewing angle.

In general, the display industry generally evaluates 13 mixed colors (White, Red, Blue, Green, Skin, Sony Red, Sony Blue, Sony Green, Cyan, Purple, Yellow, Moderate Red, Purplish Blue). Color compensation films of the type / thin film / thick film alone can not minimize the color change of all mixed colors.

The reason for this is that, as shown in FIGS. 5 and 6, when the white light emitted from the display panel is emitted at a high gradation (maximum 255 gray level), as the viewing angle increases, the luminance decreases in all wavelength regions and is relatively Although the blue wavelength region decreases fastest, as shown in FIG. 14, when emitted at low gray levels (30 gray level), the luminance increases in all wavelength regions as the viewing angle increases, and the relatively green wavelength region increases fastest. do.

Therefore, the color compensation film described above can reduce the color change due to the increase of the viewing angle at the high gradation level, but cannot reduce the color change at the low gradation level.

In the case of the mixed color, as shown in Table 1 below, the combination of light of various gray, green, red, and blue areas is implemented. Therefore, there is a limit in reducing the color change for all the mixed colors using only the color compensation film described above.

FIG. 12 is a graph showing color change Δu'v '(θ) of 13 mixed colors according to the change of viewing angle T in the LCD device, and FIG. 13 is a viewing angle θ when the aforementioned color compensation film is used in the LCD device. It is a graph showing the color change Δu'v '(θ) of 13 mixed colors according to the change.

Δu'v '(θ) refers to the difference between the distance between the color coordinates (u ₀ , v ₀ ) and the color coordinates (u _θ , v _θ ) at each viewing angle θ and can be expressed as follows.

Δu'v '(θ) = [(u ₀ -u _θ ) ² + (v ₀ -v _θ ) ² ] ^1/2

In the graph, the horizontal axis represents a horizontal angle, that is, a viewing angle.

As shown in the graphs of FIGS. 12 and 13, when the aforementioned color compensation film is used, blue-based mixed colors (Sony Blue, Purple, Purplish Blue, etc.) change color at a left and right viewing angle of 60 degrees (color shift, Δu ′). v ') decreases like H1 and H2, while red-based mixed colors (Sony Red, Moderate Red, etc.) appear to increase rather than T1 and T2, thus reducing the color change for all 13 mixed colors. There is no problem.

15 is a perspective view of a color compensation film according to an embodiment of the present invention.

The color compensation film of FIG. 15 includes a substrate 10 and a color light absorption pattern 20.

The substrate 10 may be formed of a transparent polymer resin material that serves as a light transmitting part through which light is transmitted. The substrate 10 may be basically any material that has high transparency through which light can be transmitted and can form the color light absorption pattern 20, but is light in weight and easy to handle in polyester. , At least one selected from the group consisting of acryl, cellulose, polyolefin, polyvinyl chloride, polycarbonate, phenol and urethane. 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 polyester used in the polyester system may be obtained by carrying out an esterification reaction or a transesterification reaction with an aromatic, such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, and glycol, followed by a polycondensation reaction. It can be supplied in the form.

Polycarbonates can be obtained by melt transesterification, in which bisphenols react with diaryl carbonates in the melt and release hydroxyaryl and can be supplied in the form of polymer chips.

It is preferable that the thickness T of the base material 10 is formed in 50 micrometers-1 mm. The thickness (T) of the substrate 10 is 50 μm or more so as to achieve maximum flexibility and thinning within the limit in which mechanical properties and heat resistance of the substrate can be secured. In addition, the thickness (T) of the substrate 10 to be 1mm or less to ensure the maximum mechanical properties of the substrate within the limit to ensure the flexibility, thickness and light transmittance of the substrate.

  In the method of forming a wedge-shaped indentation groove for forming the color light absorbing pattern 20 on the substrate 10, a base material composed of an ultraviolet curable resin is applied to one surface of the support, and then a shape opposite to the intaglio groove is formed on the surface. The support on which the base material is applied is passed between the indent groove forming rolls. At this time, the shape of the roll is transferred to one surface of the substrate, and then the substrate material is irradiated with ultraviolet rays to cure, thereby completing a substrate on which a negative groove is finally formed.

However, the present invention is not limited to such a molding method, but is a hot press method using a thermoplastic resin, or an injection molding method in which a thermoplastic or thermosetting resin is filled into a mold in which a shape opposite to the intaglio groove is transferred and molded. Various methods are available.

The color light absorption pattern 20 is formed on one surface of the substrate 10 so that the light emitted from the display panel increases gradually in the entire wavelength range as the viewing angle is increased, and in particular, the green color of 510 to 560 nm is relatively high. The absorption of light in the green wavelength region, the orange wavelength region, and the cyan wavelength region is greatly increased, thereby minimizing the mixed color change according to the viewing angle.

The color light absorption pattern may be completed by filling an intaglio groove of the substrate with an ultraviolet curable resin containing a green wavelength region absorbing material (Pink pigment) and a substance absorbing peaks in the orange and cyan wavelength regions, and then irradiating and curing ultraviolet rays. Can be.

As the viewing angle increases, the color light absorption pattern absorbs more of the green wavelength region of the light emitted from the display panel as the viewing angle increases, while viewing the peaks of the orange and cyan wavelength regions that adversely affect the color shift according to the viewing angle. As this increases, it serves to absorb more.

When the light emitted from the display panel is emitted in high gradation, the luminance decreases in all wavelength ranges and the green area decreases relatively late as the viewing angle increases, but when it is emitted in low gradations, all wavelength ranges increase as the viewing angle increases. The luminance increases and the green area increases the fastest at.

Since the mixed color is implemented by a combination of light of various gray, green, red, and blue regions, there is a limit in reducing color change for all mixed colors using only the color compensation film of FIG. 8 described above.

Therefore, the light emitted from the display panel increases the absorption of light in the entire wavelength region as the viewing angle increases, and the absorption of light in the green wavelength region of 510 to 560 nm is relatively increased to increase the viewing angle. It is possible to minimize the mixed color change.

On the other hand, as shown in FIG. 16, unlike the LED (shown on the left side of FIG. 16), in the case of CCFL Back Light (shown on the right side of FIG. 16), the cyan wavelength region near 490 nm and orange near 590 nm are shown. ) There is a strong peak in the wavelength range.

The peaks of the cyan and orange wavelength ranges reduce color reproduction area and cause color shift deterioration.

As a practical example, as shown in FIG. 17, the color shift result of the LCD including the LED (shown on the left side of FIG. 17) and the BLU (shown on the right side of FIG. 17) of the CCFL shows that the case of the CCFL is worse. have.

Therefore, when the peaks of the orange and cyan wavelength regions that adversely affect the color shift according to the viewing angle are absorbed more as the viewing angle increases, the mixed color change due to the increasing viewing angle may be further minimized.

In order to play such a role, the color light absorption pattern 20 includes not only a green wavelength band absorbing dye capable of absorbing light of a green wavelength of 510-560 nm, but also an orange wavelength band absorbing dye and a cyan wavelength band absorbing dye. As a result, it is possible to further increase the viewing angle improvement effect by minimizing the color change according to the increased viewing angle and minimizing the color change in all mixed colors including the blue mixed color series and the red mixed color series. In particular, when the white light absorbing material is further filled, the viewing angle improvement effect may be further increased.

Here, the green wavelength region absorbing material may be any one of inorganic and organic materials capable of absorbing light of the green wavelength of 510 ~ 560nm, it is preferable to use a pink pigment. . In addition to the pink pigment, any material capable of absorbing light of the green wavelength may be used as the green wavelength region absorbing material.

Herein, the green wavelength region absorbent material is dissolved or dispersed in the solvent or transparent resin with a weight ratio of 0.5 wt% or more, and then filled in a pattern to measure a film having a thickness of 140 μm or more, and measured from 510 nm to The transmittance of the green wavelength region of 560nm means a material having a characteristic of less than the transmittance of the 440nm ~ 480nm Blue wavelength region and 600nm ~ 650nm Red wavelength region. In particular, a pink pigment whose transmittance difference at 545 nm and transmittance at 450 nm, transmittance at 545 nm and transmittance difference at 612 nm is 5% or more.

Alternatively, the green wavelength region absorbent material is 510 nm when a wedge-shaped pattern including 0.25 wt% or more of the green wavelength region absorbent material is formed on the film at a depth of 100 µm or more, a width of 20 µm or more, and a pitch of 50 µm or less. The transmittance of the green wavelength region of ˜560 nm refers to a material having a characteristic smaller than that of the 440 nm to 480 nm blue wavelength region and the 600 nm to 650 nm red wavelength region. In particular, a pink dye having a transmittance difference of 545 nm and a transmittance of 450 nm and a transmittance difference of 545 nm and a transmittance of 612 nm of 5% or more corresponds to this.

The orange wavelength absorbing material is dissolved or dispersed in a solvent or transparent resin with a weight ratio of 0.2wt% or more, and produced in the form of a film having a thickness of 8.8 μm or more. When measured, the transmittance of 580 nm to 600 nm orange wavelength range is 560 nm or less. It means a material having characteristics smaller than the transmittance of the region and the transmittance of the wavelength region of 612 nm or more. In particular, dyes having a transmittance at 590 nm and a transmittance at 450 nm, a transmittance at 590 nm and a transmittance at 545 nm, and a transmittance difference at 590 nm and transmittance at 612 nm are 40% or more.

The cyan wavelength absorbing material is dissolved or dispersed in a solvent or transparent resin with a weight ratio of 0.2wt% or more, and produced in the form of a film having a thickness of 8 μm or more. When measured, the transmittance in the wavelength range of 490 nm to 510 nm cyan is 480 nm or less. It means a material having characteristics smaller than the transmittance of the region and the transmittance of the wavelength region of 520 nm or more. In particular, pigments having a transmittance at 500 nm and a transmittance at 440 nm, a transmittance at 500 nm and a transmittance at 545 nm, and a transmittance difference at 500 nm and transmittance at 612 nm are 25% or more.

The color light absorption pattern includes a plurality of color light absorption portions. The color light absorbing portion may typically have a wedge shape, for example, a trapezoidal or triangular shape, and are arranged parallel to one surface of the substrate 10 opposite to the display panel at regular intervals.

The color light absorbing portion is typically formed with the bottom surface of the wedge facing the panel. However, the present invention is not necessarily limited thereto, and the bottom surface of the wedge may be formed to face the viewer, or may be formed on both sides of the substrate to face both the panel and the viewer.

The color light absorption pattern may have various shapes such as wedge stripe shape, wedge wave shape, wedge matrix shape, wedge honeycomb shape, rectangular stripe shape, rectangular wave shape, rectangular matrix shape, rectangular honeycomb shape, and the like.

The color light absorption pattern 20 may be arranged in various directions such as a horizontal direction, a vertical direction, and the like with respect to the viewer. When it is formed in the horizontal direction, it is effective for vertical viewing angle compensation, and when it is formed in the longitudinal direction, it is effective for right and left viewing angle compensation. The color light absorption pattern 20 may be formed to have a predetermined bias angle with respect to the long side of the substrate to prevent moiré development.

The substrate 10 may include a color correction pigment that changes or adjusts the color balance by reducing or adjusting the amounts of red (R), green (G), and blue (G).

Since the image color of the display is changed by the color light absorption pattern when the light from the front of the display passes through the optical filter for the display device, the green wavelength region, the orange wavelength region, and the cyan wavelength region with color correction pigments on the substrate 10. A dye which absorbs other wavelength ranges, such as a red wavelength range absorbing dye and a blue wavelength range absorbing dye, may be appropriately included to correct the color close to the original color from the front. It is not provided as a separate layer or film is formed by adding a color correction pigment to the base material can simplify the structure of the optical filter and shorten the manufacturing process.

Herein, the blue wavelength absorbing material is dissolved or dispersed in a solvent or transparent resin with a weight ratio of 0.2 wt% or more, and produced in the form of a film having a thickness of 8.5 μm or more. When measured, the transmittance of 440 nm to 480 nm blue wavelength range is 510 nm to It refers to a material having characteristics smaller than the transmittance in the green wavelength region of 560 nm and the transmittance in the red region of 600 nm to 650 nm. In particular, a dye having a transmittance difference of 450 nm and a transmittance of 545 nm and a transmittance difference of 612 nm at a transmittance of 450 nm of 7% or more correspond to this.

The red wavelength absorbing material is dissolved or dispersed in a solvent or transparent resin with a weight ratio of 0.2wt% or more and produced in the form of a film having a thickness of 7.8 μm or more, and the transmittance in the wavelength range of 600 nm to 650 nm red is 440 nm to 480 nm blue. It means a material having characteristics smaller than the transmittance of the (Blue) region and the transmittance of the green wavelength region of 510 nm to 560 nm. In particular, a dye having a difference in transmittance at 612 nm and a transmittance at 450 nm and a difference in transmittance at 545 nm at a transmittance of 612 nm is 2.5% or more.

Of course, the color correction pigment may be included in the adhesive layer, the support, and the like in addition to the substrate, may be further included in the other functional film.

On the other hand, when the ultraviolet curable resin constituting the substrate has an antireflection function, an electromagnetic shielding function, a color control function or a combination thereof, the color compensation film may additionally perform these functions.

18 and 19 illustrate a case in which only the green wavelength region absorbing material is filled in the color light absorption pattern and the green wavelength region absorbing material, the orange wavelength region absorbing material, and the cyan wavelength region absorbing material, respectively, according to the change in the viewing angle of the display device. This graph shows the color change of 13 mixed colors.

In the display industry, evaluation is based on 13 mixed colors (White, Red, Blue, Green, Skin, Sony Blue, Sony Green, Cyan, Purple, Yellow, Moderate Red, and Purplish Blue).

As shown in FIG. 19, in the display apparatus using the color compensation film of FIG. 15, the color change of 13 mixed colors according to the change of the viewing angle is measured. In comparison, it can be seen that the 13 mixed colors are uniformly lowered overall.

That is, by using the color compensation film of the present embodiment, as the viewing angle increases, it is possible to absorb more light of a green wavelength, so that red-based mixed color (Sony Red, Moderate Red, etc.) and blue-based mixed color ( Sony Blue, Purple, Purplish Blue, etc.) minimize the color change, so that the color change in all mixed colors can be minimized.

In addition, as shown in FIG. 13, when looking at the color deviation of 13 mixed colors according to the change in the viewing angle of the display device to which the thick film / thin film / thick color compensation film is applied, the color deviation Δu'v 'is set to a value of 0.085. It can be seen that it appears.

However, when looking at the color deviation of the 13 mixed colors according to the change in the viewing angle of the display device to which the color compensation film of the present invention is applied, it can be seen that the color deviation Δu'v 'appears as a value of 0.035 or less.

Here, when the color deviation Δu'v 'is 0.085, the color deviation can be visually sensed by the naked eye, and the image quality decreases as the viewing angle increases. On the other hand, when the color deviation Δu'v' is 0.035 or less, the color deviation is almost naked. As it is not felt, the image quality can be improved by increasing the viewing angle.

Compared with the graph of FIG. 18 using only the pink pigment, it can be seen that Δu'v 'is greatly reduced.

In the display device to which the color compensation film of the present invention is applied, not only the blue-based mixed color and the red-based mixed color, but also the reduction ratio of the spectrum according to the increase of the viewing angle in the entire wavelength range is almost the same. Therefore, the color deviation with the increase of the viewing angle is almost disappeared.

Preferably, the color light absorption pattern includes 0.1 to 10 wt% of the green wavelength region absorbent, 0.01 to 1 wt% of the orange wavelength region absorbent, and 0.01 to 1 wt% of the cyan wavelength region absorbent.

FIG. 19 shows the color according to the increase in the left and right viewing angles when 1 wt% of the absorbing material (Pink pigment) in the green wavelength region and 0.2 wt% and 0.1wt% of the absorbing material in the orange and cyan wavelength regions are added to the color light absorption pattern. This is the result of shift (Δu'v ').

As shown, the degree of color shift reduction is superior to that of the color compensation films of FIGS. 13 and 18, and the color shift improvement is superior to all mixed colors.

20 and 21 are graphs showing the effect of the refractive index on the color change in the color compensation film including only the green wavelength region absorbing material in the color light absorption pattern, Figure 20 is the case where the refractive index of the substrate and the color light absorption pattern is the same, FIG. 21 is a graph showing color deviation according to a viewing angle when the refractive index of the color light absorption pattern is 0.06 larger than the refractive index of the substrate.

In the color compensation film including only the green wavelength region absorbing material in the color light absorption pattern, all other conditions were matched and the influence of the refractive index on the color change was measured.

As shown in Fig. 20 and Fig. 21, the color shift in the case where there is no difference in refractive index between the substrate and the color light absorption pattern is about? U'v '= 0.042 and the color shift in the case where the refractive index difference is set to 0.06 is? U'v' = There is little difference between 0.045 and so on.

On the other hand, as shown in Table 2 below, the front transmittance is larger in the case where there is a refractive index difference than when there is no difference in the refractive index.

LCD TV Same refractive index Index of Refraction 0.06 Brightness (nit) 431.5 328.3 344.8 Transmittance 100% 76% 80%

Here, the difference of 4% in the transmittance varies depending on how large the light emitted from the display device is. For example, if the brightness of the light emitted from the LCD is 50 nit (mobile phone level), the difference is about 2 nit, which is difficult to distinguish from the human eye, but if it is 500 nit or more (for an LCD TV), the difference is 20 nit. Given that the brightness of LCD TVs is increasing, the increase in transmittance of 4% has an important technical meaning in itself.

Preferably, the color light absorption pattern and the substrate have a refractive index difference of 0.001 to 0.1.

20, 21, and Table 2 show the test results when the refractive index of the color light absorption pattern is larger than the refractive index of the substrate. On the contrary, when the refractive index of the substrate is larger than that of the color light absorption pattern, the transmittance is further improved.

The above test results are for the color compensation film whose color light absorption pattern includes only the green wavelength region absorbing material, but the same applies to the color compensation film of the present invention. That is, by providing a difference in refractive index between the substrate and the color light absorption pattern, the transmittance can be improved while maintaining the color shift improving effect.

22 is a cross-sectional view of another color compensation film.

The color compensation film may include a support 40 for supporting the substrate 10.

Here, the support 40 serves as a backing so as to form the base 10 in the manufacturing process, it is preferably composed of a transparent resin film having ultraviolet transmittance. As the material of the support 40, for example, polyethylene terephthalate (PET), polycarbonate (PC), polyvinyl chloride (PVC), or the like may be used. In addition, TAC (triacetylcellulose), PVA (poly vinyl alcohol), isotropic films may also be used as a support.

An optical filter for a display device according to an embodiment of the present invention may be disposed in front of the liquid crystal panel, and in addition to the color compensation film, various functional films such as a transparent substrate, an anti-fork film, an antireflection film, and the like may be stacked on each other. have.

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 related art for improving the contrast ratio change and the color change according to a change in viewing angle.

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.

5 is a graph illustrating a result of measuring a change in emission spectrum of full white according to an increase in a viewing angle of an LCD according to the related art.

FIG. 6 is a graph normalizing the result of FIG. 5.

7 is a cross-sectional view showing an optical filter for a display device according to a comparative embodiment of the present invention.

FIG. 8 is a conceptual diagram illustrating transmission and reflection of light in the color compensation film of FIG. 7.

FIG. 9 is a graph illustrating transmittance according to a change in viewing angle of the color compensation film of FIG. 7.

FIG. 10 is a graph normalizing an LCD spectrum result to which the result of FIG. 9 is applied.

FIG. 11 is a graph illustrating a change in color coordinates with increasing viewing angle of the color compensation film of FIG. 7.

FIG. 12 is a graph showing color change of 13 mixed colors according to a change in viewing angle of an LCD device without a color compensation film.

FIG. 13 is a graph showing color change of 13 mixed colors according to a change in viewing angle of the LCD device to which the color compensation film of FIG. 7 is applied.

14 is a graph showing a result of measuring a change in emission spectrum of low grayscale white color with increasing viewing angle of a conventional LCD and a result of normalizing the same.

15 is a perspective view illustrating a color compensation film for a display device according to an embodiment of the present invention.

16 is a graph showing the emission spectra of LEDs and CCFL backlights.

17 is a view showing color shift in the horizontal direction of the LED and CCFL backlight.

FIG. 18 is a graph illustrating color change of 13 mixed colors according to a change in a viewing angle of a display device in which a color compensation film including only a green wavelength region absorbing material is applied to a color light absorption pattern.

FIG. 19 is a graph showing color change of 13 mixed colors according to a change in viewing angle of the display device to which the color compensation film of FIG. 15 is applied.

20 and 21 are graphs showing the effect of the refractive index on the color change in the color compensation film including only the green wavelength region absorbing material in the color light absorption pattern, Figure 20 is the case where the refractive index of the substrate and the color light absorption pattern is the same, FIG. 21 is a graph showing color deviation according to a viewing angle when the refractive index of the color light absorption pattern is 0.06 larger than the refractive index of the substrate.

22 is a cross-sectional view illustrating a color compensation film for a display device according to another embodiment of the present invention.

Claims (20)

A substrate transmitting light; A color light absorption pattern formed on the substrate to absorb light in a green wavelength region of 510 to 560 nm, an orange wavelength region of 580 to 600 nm, and a cyan wavelength region of 490 to 510 nm, The color light absorbing pattern is a color compensation film for a display device, characterized in that it comprises a green wavelength region absorbent material 0.1 ~ 10wt%, orange wavelength region absorbent material 0.01 ~ 1wt%, cyan wavelength region absorbent material 0.01 ~ 1wt%. delete The method of claim 1, The green wavelength absorbing material has a transmittance of 440 nm to 480 nm in the green wavelength range of 510 nm to 560 nm when a wedge-shaped pattern including 0.5 wt% or more of the green wavelength absorbing material is formed on a film having a thickness of 140 μm or more. A color compensating film for a display device, the material being smaller than the transmittance of the blue wavelength region and the 600 nm to 650 nm red wavelength region. The method of claim 1, The green wavelength-absorbing material is formed when the wedge-shaped pattern including 0.25 wt% or more of the green wavelength-absorbing material is formed on the film at a depth of 100 µm or more, a width of 20 µm or more, and a pitch of 50 µm or less. A color compensation film for display devices, characterized in that the transmittance of the green wavelength region of 560 nm is smaller than the transmittance of the 440 nm to 480 nm blue wavelength region and the 600 nm to 650 nm red wavelength region. The method according to claim 3 or 4, A color compensation film for display devices, wherein a difference in transmittance at 545 nm and a transmittance at 450 nm, and a difference in transmittance at 545 nm and transmittance at 612 nm are 5% or more. The method of claim 1, The orange wavelength range absorbing material has a transmittance in the wavelength range of 580 nm or less and a wavelength in the wavelength range of 560 nm or less and a wavelength of 612 nm or more when the orange wavelength range absorbing material is included in a film having a thickness of 8.8 μm or more and 0.2 wt% or more. A color compensating film for display devices, characterized in that it is a substance smaller than the transmittance of the region. The method of claim 6, The orange wavelength range absorbing material has a transmittance at 590 nm and a transmittance at 590 nm, a transmittance at 590 nm, and a transmittance at 545 nm when the orange wavelength range absorbing material is included 0.2 wt% or more in a film having a thickness of 8.8 μm or more. Color difference film for display devices, characterized in that the difference, the transmittance at 590nm and the transmittance difference at 612nm is 40% or more. The method of claim 1, When the cyan wavelength region absorbent material contains 0.2 wt% or more of the cyan wavelength region absorbent material in a film having a thickness of 8 μm or more, the transmittance of the 490 nm to 510 nm cyan wavelength region is 480 nm or less, and the transmittance of the wavelength region is 520 nm or more. A color compensating film for display devices, characterized in that it is a substance smaller than the transmittance of the region. 9. The method of claim 8, The cyan wavelength region absorbent has a transmittance at 500 nm, a transmittance at 500 nm, a transmittance at 500 nm, and a transmittance at 545 nm when the cyan wavelength region absorbent is included at least 0.2 wt% in a film having a thickness of 8 μm or more. Color difference film for display devices, characterized in that the difference, the transmittance at 500nm and the transmittance difference at 612nm is 25% or more. The method of claim 1, The substrate is a color compensation film for a display device, characterized in that the transparent polymer resin includes an absorbing material for absorbing light in the visible wavelength range except the green wavelength region, orange wavelength region and cyan wavelength region. The method of claim 1, A pressure-sensitive adhesive layer is laminated on one side of the substrate, The pressure-sensitive adhesive layer is a color compensation film for a display device comprising an absorbing material for absorbing light in the visible wavelength range except for the green wavelength region, orange wavelength region and cyan wavelength region. The method of claim 1, A support for supporting the substrate, wherein the substrate is laminated on the support, color compensation film for display device. The method of claim 12, The support is a color compensation film for a display device, characterized in that consisting of a transparent resin film having ultraviolet permeability. The method of claim 1, The color light absorption pattern and the substrate is a color compensation film for a display device, characterized in that having a different refractive index. The method of claim 14, The color light absorption pattern and the substrate is a color compensation film for a display device, characterized in that the refractive index difference of 0.001 ~ 0.1. The method of claim 14, The refractive index of the said base material is larger than the refractive index of the said color light absorption pattern, The color compensation film for display apparatuses characterized by the above-mentioned. The optical filter for display apparatuses provided with the color compensation film for display apparatuses of any one of Claims 1, 3, 4, and 6-16. The optical filter for display apparatuses provided with the color compensation film for display apparatuses of Claim 5. 18. The method of claim 17, And said display device is a liquid crystal display device. 19. The method of claim 18, And said display device is a liquid crystal display device.

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