CN100442090C - Color Correcting Polarizers - Google Patents

Abstract

The present invention provides a color correcting polarizer comprising a polarizer layer and at least one disc-shaped film layer. The disc-shaped film layer is optically transparent in the visible wavelength range. The disk-shaped film layer functions as a polarizer in at least the wavelength range of 380 to 500 nm and/or 600 to 780 nm. The present invention also discloses a liquid crystal cell including a color correcting polarizer.

Description

Color Correcting Polarizers

related application

This application claims the benefit of and priority to U.S. Provisional Application No. 60/442,440, filed January 24, 2003, and U.S. Application No. 10/465,083, filed June 18, 2003, the disclosures of which are incorporated herein for reference.

technical field

The present invention relates generally to liquid crystal displays, and more particularly to liquid crystal displays having color correcting polarizers.

Background technique

Most LCD monitors suffer from significant perceptual color errors. The spectral selectivity of the liquid crystal layer is one of the causes of erroneous color reproduction and grayscale coloration in liquid crystal displays.

The principle of operation of liquid crystal displays requires a polarizer. The function of the polarizer is to selectively transmit or reflect light by means of a preferred polarization direction. Unpolarized light transmitted through (or reflected by) a linear polarizer has a polarization direction collinear with the so-called transmission axis of the polarizer.

The polarizing power of a linear polarizer is characterized by the dichroic ratio. In fact, a small fraction of light whose polarization vector is perpendicular to the transmission axis is transmitted through the polarizer. Therefore, the transverse absorption coefficient (k _⊥ ) has a high but limited value. A small fraction of light whose polarization vector is parallel to the transmission axis can be absorbed by the polarizer, so the longitudinal absorption coefficient (k _∥ ) has relatively small non-zero values. The dichroic ratio is defined as:

K _d =k _⊥ /k _‖ (1)

A high dichroic ratio refers to a higher degree of polarization of light transmitted through the polarizer.

Another important property of polarizers is the spectral dependence of the dichroic ratio. The transverse and longitudinal absorption coefficients are dependent on the wavelength of light. Hence, the dichroic ratio is also wavelength dependent. This dependence manifests itself in coloring the white light that initially passes through the polarizer. A sample transmission spectrum of two perpendicularly crossed typical polarizers is shown in Figure 1. The transmission spectrum exhibits gradually increasing spectral leakage below about 550 nm and rapidly increasing leakage at long wavelengths above about 680 nm. These leaks lead to significant coloring of the polarizer. It should be noted, however, that the human visual system is extremely insensitive to wavelengths of 680nm and above, and most illumination sources for LCDs have minimum intensity in this region. Therefore, the main source of coloration due to polarizer leakage is the short wavelength region.

The described coloration can occur in different types of polarizers. Tinting values depend on the particular type of polarizer, but are still noticeable to the human eye. The transmission spectrum shown in Figure 1 is characteristic of iodine-based polarizers. Due to their relatively high dichroic ratio, these iodine-based polarizers are widely used in liquid crystal displays. Other types of polarizers, including dichroic dye-based polarizers, are also prone to coloration.

The described polarizer coloration is one of the reasons for the coloration of the liquid crystal cell. The magnitude and significance of color errors and hue changes will vary with the particular optics of the cell and display application. In some cases, users of low-cost monochrome LCDs can even tolerate relatively large color errors and hue variations. However, for color liquid crystal displays in general, and especially for high-performance, full-color active-matrix liquid crystal display panels (AMLCDs), users are beginning to demand the same high-quality color cathode ray tubes found in today's televisions and computer workstation monitors. Comparable levels of color accuracy and stability for the monitor. This specified high level of cell color performance requires the elimination of virtually all color errors and hue variations, including coloration caused by polarizers.

In particular, the origin of color errors and hue variations of liquid crystal cells can be attributed to two main reasons: the shift of the spectral transmission peak or reflection peak, which comes from the change of the effective birefringence of the liquid crystal layer and the phase retardation between the polarization components. , and deviations from ideal polarization properties as described above for the coloring of polarizers in practical polarization control films. The first source of color error usually predominates at high gray levels and can often be effectively controlled by reducing the birefringence and/or thickness of the liquid crystal layer. In contrast, polarizer-related coloration predominates at low gray scales and persists up to the black level of the display.

Therefore, it is desirable to have simple, polarization-sensitive color correction that can be applied to polarizers and liquid crystal cells. It would also be desirable to provide a color correction method with high transparency in the visible wavelength region for maintaining high transparency of polarizers or liquid crystal cells.

Contents of the invention

It is an object of the present invention to provide polarizers and liquid crystal displays with good color reproduction and grayscale reproduction.

Another object of the present invention is to provide polarizers and liquid crystal displays with full correction of color shift.

A further object of the invention is to eliminate the disadvantages of known polarizers and liquid crystal displays with cumbersome and complex color and gray scale correction systems.

These and other objects are achieved by a color correcting polarizer of the present invention comprising a polarizer layer and at least one discotic film layer. The disc-shaped film layer is optically transparent in the visible wavelength range. The disk-shaped film layer functions as a polarizer in the wavelength range of at least 380 to 500 nm and/or 600 to 780 nm.

In a specific embodiment, a liquid crystal cell including a color correcting polarizer is provided. The liquid crystal cell includes a front panel, a rear panel, a liquid crystal disposed between the front panel and the rear panel, and a color correcting polarizer. The color correcting polarizer includes at least one polarizer layer and at least one discoidal film layer. The disc-shaped film layer is optically transparent in the visible wavelength range and functions as a polarizer in the wavelength range of at least 380 to 500 nm and/or 600 to 780 nm.

Description of drawings

The present invention can be more clearly understood when reading the following detailed description in conjunction with the accompanying drawings, in which:

Figure 1 is the transmission spectrum of a pair of typical iodine-based sheet polarizers, where the transmission axes are crossed at 90°;

Fig. 2 schematically shows the basic structure of a color correction polarizer film, which includes a polarizer and a color correction disc film according to a specific embodiment of the present invention;

Figure 3 schematically illustrates a color correcting polarizer comprising a disk-shaped film layer, an adhesive layer disposed on the disk-shaped film layer, and a substrate layer in accordance with a specific embodiment of the present invention;

Figure 4 schematically illustrates a color correcting polarizer comprising a disc-shaped film layer, a substrate layer, and an adhesive layer disposed on the substrate layer in accordance with one embodiment of the present invention;

Figure 5 schematically illustrates a color correcting polarizer comprising an anti-glare (or anti-glare) coating on a disc-shaped film layer in accordance with a specific embodiment of the present invention;

Figure 6 schematically illustrates a color correcting polarizer comprising a protective layer on top of a disc-shaped film layer in accordance with a specific embodiment of the present invention;

Figure 7 is a schematic diagram of a reference example of a color liquid crystal display construction without the color correcting polarizer of the present invention;

Figure 8 is a schematic diagram of an example of a color liquid crystal display construction with a color correcting polarizer according to an embodiment of the present invention;

Figure 9 is a sample transmission spectrum of a disc-shaped film for polarized light oriented perpendicular and parallel to the transmission axis of the film;

Fig. 10A is the CIE 1976 diagram of the reference example color liquid crystal display shown in Fig. 7, wherein does not have the color correction polarizer of the present invention;

Figure 10B is a CIE 1976 diagram of the color liquid crystal display shown in Figure 8 with the color correcting polarizer of the present invention;

Figure 11 is a graph of data illustrating the neutral point chromaticity shift of reference and color corrected color liquid crystal displays on the CIE 1976 chart; and

Figure 12 is an isochromaticity difference contour (contour) line diagram showing the difference in angular chromaticity variation between reference and color corrected color liquid crystal displays, expressed as chromaticity JNDs.

Detailed ways

The present invention provides discotic dye film primary color correcting polarizers that can be used in TFT displays and liquid crystal displays (LCDs), such as twisted nematic (TN) LCDs, vertical alignment (VA) LCDs, in-plane switching (IPS) LCDs, and passive LCDs.

Disc-shaped dye-based films are potentially suitable devices for color correction. The use of dye substances for color correction purposes is well known in the art. To effectively color correct most types of LCDs, a combination of color correction performance and polarization capability is clearly required, since color errors are usually associated with a particular polarization state. In addition, most disc films have relatively high polarization properties at oblique viewing angles. This feature is important because color defects associated with polarizers become more apparent at oblique angles. In addition, discoid films often have retardation properties.

The color correcting effect can be obtained using thin crystal film (TCF) polarizers as described in US Patent Nos. 5,739,296 and 6,049,428, the disclosures of which are incorporated herein by reference. TCF polarizers available from Optiva Corporation (South San Francisco California) have small thickness and special properties, including high thermal resistance and thermal stability with respect to temperature change, high anisotropy of refractive index, anisotropy of absorption coefficient anisotropy, E-type optical properties with a single extraordinary transmission axis and two ordinary absorption axes, high polarization performance at off-angles, large dichroic ratio, and simple fabrication process. These polarizers can be made of disc shaped material.

The color correcting polarizer of the present invention includes a first polarizer layer having an incomplete color gamut (color range), and a second disc-shaped film layer. The disk-shaped film layer functions as a polarizer in the wavelength range of 380 to 500 nm and/or 600 to 780 nm. The disc-shaped film layer is optically transparent in the visible wavelength range.

Color correcting polarizers can be used in liquid crystal cells, or in liquid crystal displays that include liquid crystal cells. The color correcting polarizers are color gamut and grayscale corrected at normal and oblique viewing angles.

The liquid crystal cell of the invention comprises a plurality of layers, including a polarizer layer and at least one discotic film layer. The disk-shaped film layer functions as a polarizer in the wavelength range of at least 380 to 500 nm and/or 600 to 780 nm. The technical advantage of the present invention lies in the correction of the color gamut at the normal angle and the oblique angle of the liquid crystal cell. The invention can be used for correction of black and white states of liquid crystal cells as well as any gray scale state. The invention also corrects the color rendition of the polarizer.

In a particular embodiment of the invention, the liquid crystal cell comprises at least one polarizer layer and at least one further layer of disc-shaped thin-film polarizer, which together act as polarizers in the full visible wavelength range and have such a spectral transmission , which are optimized for a particular LCD display in order to correct the black or white or any grayscale state of the cell. This optimization involves backlight, color filters, liquid crystal cell, and other layer characteristics. The purpose of this optimization process is to have the combined properties of the polarizer and the color correction film in one layer in order to have a less complex and thinner structure of the liquid crystal display. The disk-shaped thin film polarizer layer of this embodiment functions as a polarizer in all visible wavelength ranges, and also has predetermined absorption peaks in the wavelength range from 380 to 500 nm and/or from 600 to 780 nm.

Other multilayer structures are also possible, which provide at least one disc-shaped film polarizer (which acts as a broadband polarizer in the full visible wavelength region) and one or more disc-shaped film polarizers (which are added so that at a certain Specific areas are used as different combinations of color correction films).

The discoidal thin film polarizer layer can be placed inside or outside the liquid crystal cell. A disc-shaped thin film polarizer layer with a transmission axis parallel to the analyzer can correct the black state chromaticity, while a disc-shaped thin film polarizer layer with a transmission axis perpendicular to the analyzer can correct the white state chromaticity. There is also an alternative when the disk-shaped film layer is located inside the liquid crystal cell, where the transmission axis can be positioned at a defined angle relative to the transmission axis of the analyzer. This enables discoid films to also be used as optical retarders. The angle between the transmission axis of the disc-shaped film and the analyzer can be defined by the retardation properties of the disc-shaped film layer.

For example, a transmissive unit with two perpendicularly crossed conventional polarizers can be considered. The white point chromaticity of the cell can be corrected using a disk-shaped film layer with the transmission axis perpendicular to the analyzer. Black point chromaticity can be corrected using a disk-shaped film layer with the transmission axis parallel to the analyzer. Any of the described configurations can correct the gray point when the white (or black) point returns to neutral chromaticity, such as the standard D65 white point on the CIE 1976 chart.

With respect to the standard CIE 1976 color diagram, the invention offers the possibility to restore the positions of the white point, black point, and gray point of the liquid crystal cell to the neutral chromaticity region. The use of a discoidal thin film layer polarized in the range of 380nm to 500nm enables the blue shift and black level at low gray scales to be neutralized. The use of a discotic film layer polarized in the range of 600nm to 780nm enables the yellow tint at high gray scales and the full-on state of the liquid crystal cell to be neutralized. These trends in cell coloration are features found in those cell constructions employing crossed input and output polarizers. The use of disc-shaped films polarized in the wavelength range from 380nm to 500nm and in the wavelength range from 600nm to 780nm makes it possible to simultaneously correct the yellowing tendency at high gray scales and the blue shift at low gray scales. The latter case can be achieved with one or two membranes. Where two films are used, the first film polarized in the range 380 to 500 nm and the second film polarized in the range 600 to 780 nm, the transmission axes of the two films are generally oriented perpendicular to each other. The invention can fully neutralize the chromaticity of black points, white points or gray points distorted in any direction on the color map.

The enhanced color performance of liquid crystal displays at oblique viewing angles is based on the excellent angular performance of the discotic film layer. Proper selection of disc materials and fabrication techniques provides disc films with high polarizing power at squint angles.

An advantage of the present invention is that the brightness throughput of the liquid crystal cell or polarizer to be color corrected is preserved. The disc-shaped film layer of the present invention has a high photopic transmission, ie a transmission of spectral light weighted by the photopic sensitivity of the eye. Incorporating a discotic film layer into a polarizer or liquid crystal cell, while providing effective color correction, can accomplish this function with only a minimal decrease in photopic transmittance. Typical reductions are in the range of 3 to 5%, which is negligible for most applications.

The use of discoidal thin film layers is possible with any polarizer or liquid crystal cell that relies on light polarization and includes integral polarizers. The discotic film layer can be deposited directly onto the front or rear panel of the liquid crystal cell, or onto any polarizer. This is another advantage of the invention.

In addition to the method of manufacturing a color-correcting polarizer film and/or a liquid crystal cell with a color-correcting polarizer layer, the present invention also allows the preparation of polarizers to which a disc-shaped film layer is attached prior to further manufacturing steps . This approach does not require changes to the traditional manufacturing process of LCDs.

In configurations with two disk-shaped film layers placed inside or outside the cell, the disk-shaped film with the transmission axis parallel to the analyzer provides color correction for black states and low gray scales, while the one with the transmission axis perpendicular to the The disk-shaped film of the transmission axis of the analyzer provides color correction for white states and high gray scales.

There are also some other options in the case where the discoid film layer is located inside the liquid crystal cell. Thus, the transmission axis can be positioned at an angle relative to the analyzer. This allows the disk-shaped film to additionally function as an optical retarder. The angle between the disc-shaped film and the transmission axis of the analyzer will be defined by the retardation characteristics of the disc-shaped film layer and the amount of optical retardation compensation required for a particular application.

In a specific embodiment of the invention, the discoid thin film layer has an absorption peak between 380 and 500 nm. In another embodiment, the disk-shaped thin film layer has an absorption peak between 600 and 780 nm. An absorption peak in one of said regions corrects the color gamut of the polarizer layer or the liquid crystal cell.

In another embodiment of the invention, the discotic thin film layer is made of a stabilized lyotropic liquid crystal of discotic dichroic dye molecules. The formation of a stable liquid crystalline phase in aqueous solution provides an initial ordering of the dye molecules. This ordering followed by evaporation of the solvent and orientation of the film provides a disc-shaped film layer with light polarizing capabilities. Therefore, the ability of the discotic dichroic dyes to form stable lyotropic liquid crystals is preferred in the present invention to facilitate the fabrication of polarizing discotic film layers from dichroic dye molecules.

The disc-shaped film layer used for the color correcting polarizer may be an E-type polarizer. For example, the disk-shaped thin film layer can be prepared by the sulfo derivatives of phenanthrene-9', 10': 2,3-quinoxaline of the following general structure:

Wherein, n=1-4, m=1-4, and z=0-6 so that m+z+n≤12; X and Y are CH ₃ , C ₂ H ₅ , OCH ₃ , OC ₂ H ₅ , Cl, Br, OH, or _NH2 ; M is the counterion; and j is the number of counterions in the dye molecule, which can be a fraction if the counterion is shared by several molecules (for n > 1, can be related to different counterions).

The disk-shaped thin film layer can also be prepared by a sulfo derivative of at least one of the phenanthrene-9', 10':2,3-quinoxaline of the formulas I-VIII,

m=0,1,2,3 m=0,1,2,3,4

z=0,1,2,3,4,5,6 z=0,1,2,3,4,5,6

m=0,1,2,3 m=0,1,2,3,4 m=0,1,2,3,4

z=0,1,2,3,4,5,6 z=0,1,2,3,4,5,6 z=0,1,2,3,4,5,6

m=0, 1, 2, 3 m=0, 1, 2

z=0,1,2,3,4,5,6 z=0,1,2,3,4,5,6

m=0,1,2

z=0, 1, 2, 3, 4, 5, 6

Wherein, m=0-2 _, z=0-6, while X and _Y are _CH3 , _C2H5 , _OCH3 , _OC2H5 , Cl, Br, OH or _NH2 ; M is a counter ion; and j is the number of counterions in the dye molecule, which can be a fraction if the counterion is shared by several molecules (different counterions can be involved if the number of sulfo groups is greater than 1).

The polarizing film prepared from the above-mentioned discotic molecules can function as a polarizing plate in the range of 380 to 500 nm. In addition, the polarizing film has high transparency in the visible wavelength range due to low absorption in the range of 500-780nm. In addition, dye molecules can form stable lyotropic liquid crystals with dichroic properties. These dye molecules can be used in the discoid thin film layer of the present invention.

In another embodiment of the invention, the disc-shaped film layer functions as an E-type polarizer. This E-type polarizer transmits extraordinary light waves and suppresses ordinary light waves. Disk shaped film polarizers are often E-type. The advantages of E-type polarizers are higher angular characteristics and smaller thickness. The combination of a pair of E-disk film layers and O-type polarizer layers can enhance the angular characteristics. The use of an E-type polarizer and a pair of E-type disk-shaped film layers and an O-type polarizer in a liquid crystal cell can increase contrast at normal and oblique viewing angles, improve viewing angles, enhance gray-scale stability, and provide certain other properties that depend on liquid crystals. Advantages of the box type. In another particular embodiment, the liquid crystal cell has at least one O-type polarizer layer.

In the present invention, the liquid crystal cell can be designed using an O-type polarizer layer. O-type polarizers can be made from iodine-based polymer polarizers. Iodine polarizers are often used as polarizers for liquid crystal cells and most of these polarizers have blue leakage, which includes increased transmission of a pair of perpendicularly crossed polarizing 2 plates in the short wavelength region of 380nm to 500nm. This blue leakage can lead to distorted color reproduction at low gray scales and oblique angles and reduce the color gamut of the liquid crystal cell. Correction of color gamut and color reproduction at low gray levels and oblique angles can be enhanced using a disc-shaped film layer.

In another embodiment of the present invention, the E-type polarizer layer has negative birefringence. The liquid crystal layer in a liquid crystal cell has positive birefringence. Adding layers with negative birefringence can compensate for the optical path difference between extraordinary and ordinary rays. This compensation enhances contrast at oblique and normal angles, improving color reproduction and viewing angles.

In another embodiment, a thin crystal film (TCF) polarizer is used as a disc-shaped thin film polarizer or polarizer of the present invention. In addition to the above-mentioned advantages, other advantages can also be obtained. For example, the optical properties of the film can be improved during the manufacturing process. This method makes it possible to modify the absorption spectrum of the polarizing film in order to ensure proper color reproduction and achromatism of the display. The use of dyes as the initial material also makes it possible to use such polarizers as color filters or neutral optical correction filters or as UV or IR filters.

Using the birefringence of the film, the polarizer can be used as a retarder. The viewing angle of liquid crystal cells with TCF polarizers can be improved by improving the optical anisotropy of the film.

The alignment (alignment) step can allow a system of micro-roughnesses with specific directions to be formed on the surface of the polarizer, and it makes it possible for the polarizer to be used as an alignment layer (alignment layer) of the liquid crystal layer.

The use of Thin Crystal Film (TCF) available from Optiva Corporation can increase the viewing angle, improve contrast and brightness characteristics, simplify the manufacturing process, reduce the production cost of liquid crystal displays, and expand the operating temperature range of liquid crystal cells.

TCF polarizers can be used in disc-shaped thin film polarizers that act as polarizers in all visible wavelength ranges and have a spectrum optimized for a particular cell to correct for black or white or any gray state of the cell.

At least one adhesive layer and at least one substrate can be added to the color correcting polarizer film. The role of the substrate layer is to enhance the mechanical stability of the film. In addition, the substrate layer can also be used as a color correction device, such as a layer of a liquid crystal cell. The adhesive material can be fixed to the color correction film or polarizer of the liquid crystal cell.

In another embodiment of the invention, the substrate is birefringent. The birefringence of the substrate facilitates additional functionality of the color correction film. For example, the birefringent properties of the substrate can be used as an additional antiglare layer for the color correction film. In the case where polyethylene terephthalate (PET) is used as the substrate material, the thermal stability of the color correction film can be improved.

In another particular embodiment of the invention, the color correcting polarizer film comprises at least one additional protective layer. This protective layer increases scratch resistance, mechanical stability and moisture resistance.

The color correcting polarizer film may also include an additional antireflection layer or an additional antiglare or antiglare layer. When the color correction polarizing film is used for a liquid crystal cell, the role of the antiglare layer or the antireflection layer is to suppress glare of reflected light, respectively.

In another particular embodiment of the invention, the liquid crystal cell comprises an additional reflective layer. This reflective layer is required for reflective liquid crystal cells. These reflective liquid crystal cells can use incident ambient light without the need for an integral lighting system, and these reflective liquid crystal cells have low power consumption. The reflective liquid crystal cell has a small thickness, which can reduce switching time, and provides high multiplexing rate and low dispersion.

In another embodiment of the invention, the liquid crystal cell has a reflective layer, and at least part of the reflective layer has specular reflective properties. Specular reflection provides high brightness to the liquid crystal cell due to the absence of loss of light intensity from diffuse scattering of light. In another specific embodiment, the liquid crystal cell has a reflective layer, and at least part of the reflective layer has diffuse reflective properties. The diffuse reflection of the reflective layer can expand the effective viewing cone of a reflective liquid crystal display, and can also suppress interference effects in multiple liquid crystal cell layers. In another specific embodiment, the liquid crystal cell has a reflective layer and at least part of this reflective layer is transmissive (transflective). A refractive layer refers to a reflective layer that partially transmits light from an integrating backlight. The use of a refractive layer can provide a liquid crystal cell combining the properties of a reflective cell and a transmissive cell in one unit.

In the present invention, the discotic film layer in the liquid crystal cell may also function as a retarder or a color filter, or a combination of at least two of the enumerated functions. Besides being used to correct the color reproduction of the color filters or to enhance the contrast of the retarder, the combination of functions reduces the thickness of the cell, which in turn improves the angular characteristics and simplifies the construction of the liquid crystal cell.

A layer of discotic film in a liquid crystal cell can be applied to the polarizer inside the cell. Placing the polarizer layer inside the cell, or between the transparent substrates of the liquid crystal cell, can provide additional protection for the polarizer layer from atmospheric moisture and mechanical damage, and can reduce cell thickness. Smaller cell thicknesses provide improved angular properties.

The invention will now be described with reference to the accompanying drawings.

Figure 1 shows the transmission spectrum of a typical iodine polarizer with a pair of transmission axes crossing at 90°. Axis 101 represents wavelength, while axis 102 represents transmittance. This graph shows a typical disadvantage of conventional polarizers, which is related to spectral leakage in the blue-violet region from 350 to 530 nm. Although the leakage in the red region has significantly high values, it is not so important in LCD applications. This is due to the relatively low radiant intensity of most backlighting systems in the red region, and the very low photopic sensitivity of the human eye in the wavelength region above 680nm. Thus, the white point on a color diagram for a typical display involving a pair of such conventional polarizers may experience a gradual shift from the desired achromatic standard towards the blue region as the gray scale decreases and approaches black level.

FIG. 2 shows the basic construction of a color correcting polarizer according to a specific embodiment of the present invention. The color correcting polarizer includes a polarizer layer 202 and a disk-shaped film layer 201 . The discotic thin film layer is composed of discotic molecules 203 . The discotic film layer also acts as a polarizer, which can be spectrally selective and birefringent. Although the basic construction shown in Figure 2 includes only two layers, other layers may also be included in order to enhance the functionality of the color correcting polarizer.

FIG. 3 shows a construction comprising a disc-shaped film layer 201 , an adhesive layer 301 , and a substrate layer 302 , wherein the adhesive layer 301 is placed on top of the disc-shaped film layer 201 . This configuration shows one possible application of the invention. An adhesive layer 301 is introduced to secure the disk-shaped film layer 201 to the polarizer, or to any surface of the liquid crystal cell. The disk-shaped film layer 201 and the adhesive layer 301 are sequentially deposited on the substrate layer 302 . The substrate layer may be required as a mechanical basis for the alignment of the disk-shaped thin film layers. Substrate layer 302 may be birefringent or non-birefringent. For example, the substrate can be made of polyethylene terephthalate (PET), TAC, and PMMA.

FIG. 4 shows a construction comprising a disc-shaped film layer 201 , an adhesive layer 301 , and a substrate layer 302 on which the adhesive layer 301 is placed. The location of the adhesive layer 301 makes this configuration different from that shown in FIG. 3 . The substrate layer 302 in FIG. 4 may be non-birefringent.

Figures 3 and 4 illustrate one of the applications of the present invention. The layers with the adhesive layer 301 placed on the side can be fixed to any other surface by means of the adhesive layer. Thus, the disk-shaped film layer 201 supported by the substrate 302 and equipped with the adhesive layer 301 can be used for color correction of any liquid crystal cell or polarizer.

FIG. 5 shows a construction comprising a disc-shaped film layer 201 with an anti-glare or anti-glare coating 501 deposited onto the disc-shaped film layer 201 . An anti-glare or anti-glare coating 501 is used in liquid crystal displays to improve the contrast and brightness of cells operating in ambient light.

FIG. 6 shows a construction comprising a disc-shaped film layer 201 with a protective layer 601 placed on the disc-shaped film layer 201 . This protective layer 601 can be placed on the disc shaped thin film layer or it can be further placed on any layer deposited on the disc shaped thin film layer. The protective film layer 601 provides protection from atmospheric moisture, mechanical damage, and enhances scratch resistance.

Example 1

The technical advantages provided by the present invention were investigated using two active matrix liquid crystal displays. As shown in Figure 7, the first display was not color corrected and served as a control for comparison. As shown in Figure 8, a second display was color corrected to illustrate the results obtained by the present invention. Figures 9 to 12 show the results obtained.

Figure 7 shows the structure of a control liquid crystal display without the color correcting polarizer of the present invention. The basic design parameters for this configuration are as follows: (1) High efficiency Nitto G-1224-DU sheet polarizers (701, 707) with transmission axes aligned at a 45° angle at the rear of the liquid crystal cell (707) and front inspection The transmission axis of the position of the polarizer (701) is aligned at -45°; (2) in the liquid crystal layer (706), twisted 90° clockwise from -45° relative to the rear substrate to -135° relative to the front substrate , so that the alignment of the rubbing direction and the orientation of the polarizer together constitute a normal white (NW) O-mode (O-mode) alignment; (3) a disk-shaped compensation film of Fuji Film with a TAC substrate (702), which is located in the liquid crystal layer (706) and between the polarizer (707) at the rear of the box and the polarizer (701) at the front, and arranged along the rubbing direction of the liquid crystal layer; (4) MLC-12000-000 liquid crystal material (706), with k ₁₁ =9.3e ⁻¹² , k ₂₂ =5.8e ⁻¹² , k ₃₃ =15.9e ⁻¹² , ε∥=12.95, ε⊥=3.55, _{n o} @550nm=1.4762 and ne@550nm=1.5639;( 5) A cell gap of 4.5 μm, a pretilt angle of 2°, and a thickness-to-spacing ratio (d/p) of 0.0495; (6) a liquid crystal driving voltage of 0 V in the field-off state, and a liquid crystal driving voltage of 0 V in the field-off state (field-off state) (7) 800 A ITO transparent electrode (704) material and 400 A polyamide alignment layer (705) at the boundary of the liquid crystal layer; (8) Corning#1737 glass substrate of 1.1mm (703); (9) a set of Topan RGB color filters (708) with a thickness of 1.6 μm; and (10) a Landmark triple-band RGB fluorescent backlight spectrum for the illumination source (709).

FIG. 8 shows the structure of a simulated liquid crystal display for demonstrating the technical advantages resulting from the present invention. Compared with the reference liquid crystal display shown in FIG. 7, the liquid crystal display shown in FIG. 8 further includes a disc-shaped thin film layer 801. Referring to FIG. A disc-shaped film layer 801 is provided on the front surface of a polarizing plate (analyzer) (701) in order to correct the color characteristics of the display.

Figure 9 shows the transmission spectra of a disc-shaped color correction film for polarized light oriented perpendicular and parallel to the transmission axis of the disc-shaped film. The X-axis 901 represents wavelength in nanometers, while the Y-axis 902 represents the transmittance of the disc-shaped film. The transmission spectrum of polarized light oriented parallel to the transmission axis of the disc-shaped film is represented by curve 903 , while the transmission spectrum of polarized light oriented perpendicular to the transmission axis of the disc-shaped film is represented by curve 904 . Figure 9 shows the ability of the disk-shaped films of the present invention to polarize light in the 380 to 500 nm region. Figure 9 also shows the high transmittance of this film in the region of 500nm to 780nm. This is evidence of the high photopic transmittance of the disc-shaped films of the present invention.

Figure 10A shows a CIE 1976 diagram of a liquid crystal display as shown in Figure 7 without the color correcting polarizer of the present invention. Figure 10B shows a CIE 1976 diagram of the liquid crystal display shown in Figure 8 with the color correcting polarizer of the present invention. FIG. 10A depicts the positions of black (Blk) and white (W) points on a color chart for a reference liquid crystal display. The point marked D65 provides reference chromaticity for CIE standard white illuminant (illuminant,) D65. The black point is obtained from the off state of the liquid crystal cell, and the white point is obtained from the on state. FIG. 10B depicts the positions of the black point and the white point on the color chart of the liquid crystal display of the present invention. With the P22 phosphor primary color (1002), the triangular border area separates the color gamut border of the liquid crystal display (1001) from the color gamut border of the reference color CRT. The black and white points of the liquid crystal display with the color correcting polarizing layer (FIG. 10B) are closer to each other, and the points are closer to the standard D65 white point. When comparing its chromaticity coordinates against the D65 white point in Figures 10A and 10B, this indicates effective color correction performance, especially the neutralization of the blue-shifted black point (Blk).

Figure 11 shows the neutral point chromaticity shift on the CIE 1976 diagram for reference and color corrected display configurations. Curve 1102 was obtained with respect to a reference display, while curve 1101 was obtained with respect to a color corrected display. Figure 11 demonstrates the effect of a disk shaped film polarizer on color tracking performance over the entire range of displayed intensity levels. The present inventors have determined that photopicity occurs in order to produce photopicity at the following percentages relative to white peak photopic luminance (0 volts) of 80%, 60%, 40%, 20%, 10%, 5%, 1%, 0.5% The LC voltage that needs to be applied for gray scale, and the LC voltage that needs to be applied for black (5 volts). The chromaticity coordinates of the white point are then calculated at each photopic gray scale. The resulting curves, shown in Figure 11, illustrate the chromaticity variation of the white point (ie, color tracking error) over the full intensity range of the AMLCD in the reference and color-corrected configurations. It can be clearly seen that the chromaticity variation of the display neutral point of the color corrected display (1101) is significantly reduced relative to the uncorrected reference display (1102) over the entire range of display intensity levels.

Figure 12 shows cross-constructed difference contours (contours) showing the angular to chromaticity variation of the black state, expressed in chromaticity JNDs. Because it is difficult to visually assess the viewing angle-dependent reduction in hue change from two separate isochromatic curves, a color difference contour curve was generated at each angle that results from the Δu'v between the color-corrected and reference constructs ' value difference. Recent standards in display metrology have stated that Δu'v' = 0.004 constitutes the just discrimination difference (JND) of chromaticity for most observers. To more directly express cross-tectonic differences in units of apparent chromaticity differences, the contour scale has been changed to chromaticity JNDs units. Negative values of the contour lines indicate angular regions where the color correction configuration has reduced hue variation relative to the same angular position in the baseline configuration. Positive contour values indicate angular regions where the reference construction provides less angular hue variation. From Figure 12 it is clearly observed that the contours are negative almost everywhere except along the main diagonal where they tend to zero. In this contour difference curve, a significant reduction in tonal variation along the aforementioned horizontal and vertical axes is evident. This last curve is expressed in units that estimate that these color differences are associated with the observer's perception.

The color correcting polarizer films of the present invention can be used in direct view transmissive and reflective modes for color correction of liquid crystal displays as well as for projection system applications. The invention finds application in different types of liquid crystal displays, including twisted nematic and super twisted nematic liquid crystal displays, and in different types of TFT displays, such as those based on homeotropic and in-plane switching technologies.

As mentioned above, the color correcting polarizer has been described. The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise form disclosed, and many modifications, embodiments, and variations are obviously possible in light of the above teaching. Accordingly, the scope of the invention is defined by the claims appended hereto and their equivalents.

Claims (34)

1. color correcting polarizer comprises:

Layer of polarizer; And

At least one disc-shaped film layer, wherein

Described disc-shaped film layer is optically transparent in visible wavelength range, and the effect of polarizing plate at least 380 to 500nm wavelength coverage, and wherein, described disc-shaped film layer is by making based on the lyotropic liquid crystal of dish type dichroic dyestuff molecule.

2. color correcting polarizer according to claim 1, wherein said layer of polarizer has the parallel or vertical axis of homology with described at least one disc-shaped film layer.

3. color correcting polarizer according to claim 1, wherein said disc-shaped film layer plays E type polaroid.

4. color correcting polarizer according to claim 3, wherein said E type polaroid has negative birefringence.

5. color correcting polarizer according to claim 1, wherein said disc-shaped film layer are thin crystal film polarizers.

6. color correcting polarizer according to claim 1, wherein said layer of polarizer are thin crystal film polarizers.

7. color correcting polarizer according to claim 1, wherein said disc-shaped film layer be by the phenanthro--9 of following general structure ', 10 ': 2, the sulfonic derivative of 3-quinoxaline is made,

Wherein, n one is selected from 1,2,3 and 4 numerical value, and m one is selected from 1,2,3 and 4 numerical value, and z one is selected from 0,1,2,3,4,5 and 6 numerical value, so that m+z+n≤12; X and Y are CH ₃, C ₂H ₅, OCH ₃, OC ₂H ₅, Cl, Br, OH or NH ₂M is counter ion counterionsl gegenions; And j is the number of counter ion counterionsl gegenions in the dye molecule, if described counter ion counterionsl gegenions are shared by several molecule, then it is a mark, for n＞1, relates to identical or different counter ion counterionsl gegenions.

8. color correcting polarizer according to claim 7, wherein said disc-shaped film layer be by the phenanthro--9 one of at least of structural formulas I-VI II ', 10 ': 2, the sulfonic derivative of 3-quinoxaline is made:

m＝0，1，2，3 m＝0，1，2，3，4

z＝0，1，2，3，4，5，6 z＝0，1，2，3，4，5，6

m＝0，1，2，3 m＝0，1，2，3，4 m＝0，1，2，3，4

z＝0，1，2，3，4，5，6 z＝0，1，2，3，4，5，6 z＝0，1，2，3，4，5，6

m＝0，1，2，3 m＝0，1，2

z＝0，1，2，3，4，5，6 z＝0，1，2，3，4，5，6

m＝0，1，2

z＝0，1，2，3，4，5，6

Wherein, m one is selected from 0,1,2,3 and 4 numerical value, and z one is selected from 0,1,2,3,4,5 and 6 numerical value, and X and Y are CH ₃, C ₂H ₅, OCH ₃, OC ₂H ₅, Cl, Br, OH or NH ₂M is counter ion counterionsl gegenions; And j is the number of counter ion counterionsl gegenions in the dye molecule, if described counter ion counterionsl gegenions are to be shared by several molecule, then it is a mark, if the number of sulfo group greater than 1, then relates to identical or different counter ion counterionsl gegenions.

9. color correcting polarizer according to claim 1 further comprises at least one bonding material layer.

10. color correcting polarizer according to claim 1 further comprises at least one birefringent layers.

11. color correcting polarizer according to claim 1 further comprises a protective seam.

12. color correcting polarizer according to claim 1 further comprises an anti-reflecting layer.

13. color correcting polarizer according to claim 1 further comprises an antiglare layer.

14. a liquid crystal cell comprises:

Front panel;

Rear panel;

Be placed on the liquid crystal between described front panel and the described rear panel; And

Color correcting polarizer, wherein

Described color correcting polarizer comprises at least one layer of polarizer and at least one disc-shaped film layer, and described disc-shaped film layer is optically transparent in visible wavelength range, and the effect of polarizing plate at least 380 to 500nm wavelength coverage,

Wherein said disc-shaped film layer is by making based on the lyotropic liquid crystal of dish type dichroic dyestuff molecule.

15. liquid crystal cell according to claim 14, wherein said layer of polarizer has the parallel or vertical axis of homology with at least one disc-shaped film layer.

16. liquid crystal cell according to claim 14, wherein said disc-shaped film layer also are polaroid in described visible wavelength range.

17. liquid crystal cell according to claim 14, wherein at least one layer of polarizer is an O type polarizer.

18. liquid crystal cell according to claim 17, wherein said O type polarizer is an iodo polymkeric substance polarizer.

19. liquid crystal cell according to claim 14, wherein at least one layer of polarizer is an E type polarizer.

20. liquid crystal cell according to claim 19, wherein said E type polarizer are by making based on the lyotropic liquid crystal of dish type dichroic dyestuff molecule.

21. liquid crystal cell according to claim 14, wherein said disc-shaped film layer plays E type polaroid.

22. liquid crystal cell according to claim 21, wherein said E type layer of polarizer has negative birefringence.

23. liquid crystal cell according to claim 14, wherein said disc-shaped film layer are thin crystal film polaroids.

24. liquid crystal cell according to claim 19, wherein said layer of polarizer are thin crystal film.

25. liquid crystal cell according to claim 19, wherein said E type layer of polarizer be by the phenanthro--9 of following general structure ', 10 ': 2, the sulfonic derivative of 3-quinoxaline is made:

Wherein, n one is selected from 1,2,3 and 4 numerical value, and m one is selected from 1,2,3 and 4 numerical value, and z one is selected from 0,1,2,3,4,5 and 6 numerical value, so that m+z+n≤12; X and Y are CH ₃, C ₂H ₅, OCH ₃, OC ₂H ₅, Cl, Br, OH or NH ₂M is counter ion counterionsl gegenions; And j is the number of counter ion counterionsl gegenions in the molecule, if described counter ion counterionsl gegenions are shared by several molecule, then it is a mark, for n＞1, relates to identical or different counter ion counterionsl gegenions.

26. liquid crystal cell according to claim 25, wherein said E type layer of polarizer be by the phenanthro--9 one of at least of structural formulas I-VI II ', 10 ': 2, the sulfonic derivative of 3-quinoxaline is made,

m＝0，1，2，3 m＝0，1，2，3，4

z＝0，1，2，3，4，5，6 z＝0，1，2，3，4，5，6

m＝0，1，2，3 m＝0，1，2，3，4 m＝0，1，2，3，4

z＝0，1，2，3，4，5，6 z＝0，1，2，3，4，5，6 z＝0，1，2，3，4，5，6

m＝0，1，2，3 m＝0，1，2

z＝0，1，2，3，4，5，6 z＝0，1，2，3，4，5，6

m＝0，1，2

z＝0，1，2，3，4，5，6

Wherein, m one is selected from 0,1,2,3 and 4 numerical value, and z one is selected from 0,1,2,3,4,5 and 6 numerical value, and X and Y are CH ₃, C ₂H ₅, OCH ₃, OC ₂H ₅, Cl, Br, OH or NH ₂M is counter ion counterionsl gegenions; And j is the number of counter ion counterionsl gegenions in the molecule, if described counter ion counterionsl gegenions are shared by several molecule, then it is a mark, if the number of sulfo group greater than 1, then relates to identical or different counter ion counterionsl gegenions.

27. liquid crystal cell according to claim 14 further comprises the anti-dazzle or antireflecting coating that is arranged on the described liquid crystal cell outside surface.

28. liquid crystal cell according to claim 14 further comprises the reflection horizon.

29. liquid crystal cell according to claim 28 wherein has the direct reflection performance to the described reflection horizon of small part.

30. liquid crystal cell according to claim 28 wherein has the scattered reflection performance to the described reflection horizon of small part.

31. liquid crystal cell according to claim 28 is transmissible to the described reflection horizon of small part wherein.

32. liquid crystal cell according to claim 14, wherein said disc-shaped film layer plays retardation plate.

33. liquid crystal cell according to claim 14, wherein said color correcting polarizer further comprises color filter.

34. liquid crystal cell according to claim 14, wherein said disc-shaped film layer is applied on the layer of polarizer of the color correcting polarizer that is arranged in described box inside.

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