JPH03191327A - Phase difference plate and liquid crystal cell - Google Patents

Abstract

PURPOSE:To enhance the accuracy of the compensation of the elliptically polar ized light specific to each of color units and to attain the adjustment of multicolors excellent in sharpness by providing a phase difference layer varied in phase difference in correspondence to the plural color units in color filter layers. CONSTITUTION:A light transparent substrate 4 has the phase difference layer 3 and the color filter layers 2 of the plural color units and the phase difference layer 3 has the phase differences varying according to the number of the color units. In addition, the respective color units in the color filter layers 2 are disposed in correspondence to the different phase differences thereof. Namely, the phase difference layers 3 varying in the phase difference with each of the color units is formed and, therefore, the phase differences suitable for the com pensation of the elliptically polarized light varying with each of wavelengths (colors) are formed. The spectra of the light transmitted through a liquid crystal cell are controlled to the specta suitable for the color units (color developing sources) in the color filter layers 2. Thus, the multicolor display which is bright and is excellent in color reproducibility is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a retardation plate having a retardation layer corresponding to the color of a color filter layer, and a color display type using the retardation plate having excellent color reproducibility and viewing angle. This invention relates to a birefringent liquid crystal cell.

Conventional technology and issues STN (Super Twisted Nemati)
c) Large-screen black-and-white liquid crystal display devices using a simple matrix drive method that take advantage of the high-speed response of liquid crystals have become widespread in personal computers, word processors, etc., but multicolor display has become an issue.

Conventionally, as a means of realizing black and white display, a certain retardation plate was interposed between the liquid crystal cell and the polarizing plate to compensate for the elliptically polarized light due to the birefringence of the STN liquid crystal, and the display through the polarizing plate was yellow-green. BF that prevents coloring such as
The TN method was known. This method has the advantage of being thinner, lighter, and easier to manufacture than the D-3TN method in which liquid crystal cells are stacked one on top of the other.

However, in the above-mentioned BFTN liquid crystal cell, RGB
When a color filter is added to display a multicolor display, there are problems in that the viewing angle is narrow (with good color reproducibility) and the contrast changes greatly depending on the viewing angle, resulting in poor visibility.

Means for Solving the Problems The present invention overcomes the above problems by using a retardation plate having a retardation layer having different retardations corresponding to a plurality of color units in a color filter layer.

That is, the present invention has a retardation layer and a color filter layer made up of a plurality of color units on a transparent substrate, and the retardation layer has a different retardation depending on the number of color units, and
A retardation plate characterized in that each color unit in a color filter layer is arranged corresponding to the different retardation.
Furthermore, in a liquid crystal cell comprising a birefringent liquid crystal sealed between cell substrates having transparent electrode layers, at least one of the cell substrates has a retardation layer and a color filter layer on one side of the transparent substrate. A liquid crystal cell comprising a retardation layer provided with a transparent electrode layer, and characterized in that the cell substrate is arranged with the side having the retardation layer as the liquid crystal side, and polarizing plates are arranged on both sides of the liquid crystal cell. The present invention provides a color display liquid crystal cell characterized by:

By creating a retardation layer with a different retardation for each working color unit, it is possible to form a retardation layer suitable for compensating for elliptically polarized light, which differs for each wavelength (color). The color unit (coloring source) in the filter layer can be controlled to be suitable, thereby achieving a clear multicolor display with excellent color reproducibility.

In addition, a liquid crystal cell is formed by forming a cell substrate in which a transparent electrode layer is provided on a retardation plate having a retardation layer and a color filter layer on one side of a transparent substrate, with the side having the retardation layer being the liquid crystal side. It is possible to widen the viewing angle for good visibility.

EXAMPLE The retardation plate of the present invention is illustrated in FIG. This has a retardation layer 3 on a transparent substrate 4 made of a glass plate, and a color filter layer 2 on top of the retardation layer 3. The retardation layer 3 is formed to have a different retardation corresponding to each color unit of the color filter layer 2, which is made up of line units G1, blue units B1, and red units R thereon. The green, blue, and red color units forming the color filter layer 2 are arranged as pixel groups partitioned for each display element.

Note that 1 in the figure is an overcoat layer provided as necessary, and is usually formed as a transparent resin layer or the like. It is preferable that the resin used has high heat resistance and excellent cured density within a range that does not impair adhesion.

In the present invention, as the light-transmitting substrate, any suitable material that transmits light may be used. Generally, a glass plate or a transparent plastic film is used. The thickness of the light-transmitting substrate is usually 5 m or less, but may be determined as appropriate depending on the light transmittance, etc., and from the viewpoint of the viewing angle, the thinner it is, the more advantageous it is.

The retardation layer has a different retardation for each color unit in order to have a retardation suitable for the coloring source. Different retardations may be realized by providing retardation layers on the front and back sides of the transparent substrate. A retardation layer having partially different retardations may be formed by any appropriate method. A formation method using vapor deposition such as a multi-stage vapor deposition method in which masking is sequentially performed using a photosensitive resist or the like is preferable. that time,
A retardation layer having optical rotation may be formed by rotating the light-transmitting substrate. As the vapor deposition method, an appropriate method such as a resistance heating method, an electron beam method, a sputtering method, or an ion beam method may be adopted (the electron beam method is preferable. Methods of changing the deposition angle, such as diagonal deposition (Japanese Patent Application Laid-open No. 5
9-49508), and a method in which the layer thickness is changed is preferred. As the vapor deposition substance, one that forms a birefringent, transparent vapor deposition layer is used. Generally, materials used include organic polymers, inorganic materials such as metals and ceramics, and those that form a vapor deposited layer with excellent transparency. In particular, from the viewpoint of durability, transparency, and birefringence, for example, Ta20s, ZrO2, TlO2, A1゜03
, Fe2O3 and other oxide-based inorganic compounds are preferably used. During the vapor deposition process, an inorganic film made of silica, alumina, titania, etc. may be provided in advance on the surface on which the vapor deposited layer is to be formed to facilitate the formation of the vapor deposited layer.

The color filter layer is formed of a plurality of color units such as red, green, and blue, and each color unit is arranged to correspond to a different phase difference of the retardation layer. That is, the same color units are arranged in the same phase difference portion. The combination of color units and the number thereof may be determined as appropriate. The color filter layer may be disposed on the light transmission path of the retardation plate. Therefore, for example, it may be arranged between the light-transmitting substrate and the retardation layer, or on the surface of the light-transmitting substrate opposite to the surface on which the retardation layer is provided. Further, they may be distributed and arranged on both sides of the transparent substrate. The color scheme for each color unit is, for example, T
A triangular shape for V or the like may be determined as appropriate. Formation of a color filter layer consisting of a plurality of color units can be performed by providing a filter material that achieves a predetermined color development at a predetermined location using an appropriate method such as a dispersion method, a dyeing method, a printing method, or a vapor deposition method. There are no particular limitations on the filter material used, and any known organic or inorganic filter material may be used.

The retardation plate of the present invention can be preferably used, for example, as a cell substrate for forming a liquid crystal cell by providing a transparent electrode layer thereon. The side on which the transparent electrode layer is provided is the liquid crystal side of the cell. A retardation plate of the present invention that can be preferably used for forming a liquid crystal cell has a retardation layer and a color filter layer on one side of a transparent substrate. Due to the bent shape, a liquid crystal cell having a retardation layer, a color filter layer, and a transparent electrode layer on the liquid crystal side can be formed, and a viewing angle can be widened.

In the liquid crystal cell of the present invention, when a birefringent liquid crystal such as an STN liquid crystal is sealed between cell substrates, a small number of cell substrates (at least one cell substrate is used, and It is formed with the side having the retardation layer facing the liquid crystal (inside). An example is shown in Fig. 2. 6.8 is the cell substrate, 7 is the birefringent liquid crystal, and the cell substrate 8 is the liquid crystal side. The retardation plate of the present invention is used. 5 is a polarizing plate, which is placed on both sides of the liquid crystal cell, thereby achieving multicolor display. 71 is a sealing layer.

The cell substrate 6 includes a transparent electrode layer 62 on one side of a transparent substrate 61.
and an alignment film 63 are sequentially formed. The cell substrate 8 has a retardation layer 3 on one side of a transparent substrate 4, and a transparent electrode layer 82 on a retardation overcoat layer having a color filter layer 2 and an overcoat layer 1 thereon. and an alignment film 81 are sequentially formed. A cell substrate 6 having a retardation layer may also be used.

The transparent electrode layer may be appropriately formed using a transparent conductive material such as indium oxide or tin oxide. From the viewpoint of protecting the function of the color filter layer, it is preferable to use a low-temperature thin film formation method such as a sputtering deposition method. The alignment film provided as necessary on the transparent electrode layer may be any transparent layer that can align liquid crystal.

Generally, it is formed as a rubbing film, an obliquely vapor deposited layer, etc., made of an organic polymer such as polyimide, polyamide, or polyvinyl alcohol, or an inorganic material such as silica, titania, or alumina.

As the polarizing plate, a polarizing film is generally used, but a glass-based plate may also be used. A polarizing film can be obtained, for example, by treating a hydrophilic film such as a stretched polyvinyl alcohol film with a dichroic dye such as iodine, or by appropriately treating a plastic film to orient polyene. Note that a retardation plate made of a plastic film or the like may be interposed between the polarizing plate and the liquid crystal cell.

Example 1 A Ta205 evaporated film was formed on one side of a glass substrate with a smooth surface by a vacuum oblique evaporation method using electron beam heating, and a photosensitive resist was applied thereon and exposed to form a mask having a predetermined pattern. A Ta205 evaporated film was formed according to the method described above, and the mask was removed. The incident angle in the above-mentioned oblique vapor deposition was 45 degrees. Next, a photosensitive resist is further coated and exposed to form a mask having a predetermined pattern, and then a Ta205 vapor deposited film is formed in the same manner as above.
After removing the mask, the thickness of the Ta205 deposited film was 3.6JJ.
A retardation layer consisting of 11, 3.94 or 4.2 parts was obtained. Each portion of the Ta205 vapor deposited film having a different thickness is divided into pixels. Next, a green filter layer was formed on the 3.6 um thick portion, a blue filter layer was formed on the 3.9 um thick portion, and a red filter layer was formed on the 4.2I7n+ thick portion to obtain a retardation plate.

Next, a transparent electrode layer made of a vapor-deposited layer of indium tin oxide is formed on the filter layer, a polyimide alignment film is provided on the transparent electrode layer, and a cell substrate is obtained. ST with the alignment film side inside together with the cell substrate having a transparent electrode layer and a polyimide alignment film.
N liquid crystal was sealed to obtain a liquid crystal cell, and polyvinyl alcohol/iodine polarizing films were adhered to both sides of the cell to obtain a color display type liquid crystal cell.

Example 2 Rotating the glass substrate during vapor deposition treatment to obtain optically active Ta20
5 Same as Example 1 except that a deposited film was formed.
As a result, a retardation plate and a color display type liquid crystal cell were obtained. The thickness of the Ta205 vapor deposited film in the green, blue, and red filter layer portions is 3.1 μs, 3.3 μs, and 3.51 μs, respectively.
It is 711.

Comparative Example 1 Same as Example 1 except that a cell substrate consisting of a retardation plate having a retardation layer and a color filter layer on one side of a glass substrate was arranged so that the retardation layer was on the outside to form a liquid crystal cell. A color display type liquid crystal cell was obtained. However, the transparent electrode layer was provided directly on the glass substrate surface so that it was placed on the liquid crystal side.

Comparative Example 2 A retardation plate,
A color display type liquid crystal cell was obtained.

Comparative Example 3 A liquid crystal cell was formed using two glass substrates, a transparent electrode layer made of an indium tin oxide vapor-deposited layer, and a cell substrate having a polyimide alignment film. A color display type liquid crystal cell was obtained in accordance with Example 1 except that a retardation plate having a retardation of 280 nm made of a polycarbonate film was interposed.

Evaluation Test Regarding the color display type liquid crystal cells obtained in Examples 1 and 2 and Comparative Examples 2 and 3, the chromaticity of each color of red, green, and blue was measured to determine color reproducibility. The results are shown in Figure 3.

Further, for the color display type liquid crystal cells obtained in Example 1 and Comparative Examples 1 and 3, the left and right viewing angles showing good color reproducibility were determined. As a result, in Example 1, 130
However, in Comparative Examples 1 and 3, the range was narrow, 125 degrees to 30 degrees, and -25 degrees to 28 degrees, respectively.

Furthermore, for a color display type liquid crystal cell formed using a retardation plate provided with a ZrO2 vapor deposited film instead of a Ta205 vapor deposited film, results showing the same tendency as the above-mentioned Examples and Comparative Examples were obtained. It was confirmed that this effect is due to the structural characteristics of the layers and liquid crystal cells.

Effects of the Invention According to the present invention, since the retardation plate has a retardation layer having a different retardation for each color unit of the color filter layer, it is possible to compensate for elliptically polarized light peculiar to each color unit with high precision. , you can adjust multi-colors with excellent clarity.

As a result, it is possible to obtain a multi-color birefringent liquid crystal cell with excellent color reproducibility using such a retardation plate, and by arranging the retardation layer and color filter layer within the cell, a liquid crystal cell with a wide viewing angle can be obtained. Obtainable.

[Brief explanation of drawings]

FIG. 1 is an explanatory sectional view illustrating a retardation plate, FIG. 2 is an explanatory sectional view illustrating a liquid crystal cell, and FIG. 3 is a graph showing color reproducibility. 2: Color filter layer 3: Retardation layer 4: Transparent substrate 5: Polarizing plate 6.8: Cell substrate 7: Birefringent liquid crystal 62.82
:Transparent electrode layer

Claims (1)

[Claims] 1. A light-transmitting substrate has a retardation layer and a color filter layer consisting of a plurality of color units, and the retardation layer has a different retardation depending on the number of color units, and , a retardation plate characterized in that each color unit in a color filter layer is arranged corresponding to the different retardation. 2. A liquid crystal cell comprising a birefringent liquid crystal sealed between cell substrates having transparent electrode layers, wherein at least one of the cell substrates has a retardation layer and a color filter layer on one side of the transparent substrate. A liquid crystal cell comprising the retardation plate according to item 1 provided with a transparent electrode layer, the cell substrate being arranged with the side having the retardation layer facing the liquid crystal. 3. A liquid crystal cell for color display, characterized in that polarizing plates are arranged on both sides of the liquid crystal cell according to claim 2.