JP2532242B2 - Color liquid crystal display - Google Patents

Description

The present invention relates to a color liquid crystal display device.

(Prior Art) A conventional color liquid crystal display device is such that a color filter is formed outside a liquid crystal cell formed by sandwiching nematic liquid crystal twisted and aligned at about 90 degrees or inside the liquid crystal cell, and the liquid crystal cell is sandwiched. A pair of polarizing plates are arranged on both sides.
At least one set of the polarization axis of the polarizing plate and the liquid crystal molecule axis direction adjacent to the electrode substrate adjacent to the polarizing plate is parallel, and the other is vertical. Therefore, the light passing through the polarizing plate becomes linearly polarized light, and the polarization direction is twisted in the liquid crystal layer according to the twist of the liquid crystal molecules, and the polarization axis of the polarizing plate on the opposite side is aligned with the liquid crystal molecule axis direction adjacent to the electrode substrate. If they are parallel, the light will pass through,
If it is vertical, it will be cut off. When a voltage is applied, the liquid crystal molecules are aligned perpendicularly to the electrode substrate, and the optical activity is lost,
The mode opposite to that when no voltage is applied is shown. When such a liquid crystal display device is in the transmissive mode, the transmitted light is colored by passing through the color filter to perform color display.

[Problems to be solved by the invention]

Since the above-mentioned conventional technique utilizes a so-called twisted nematic (hereinafter referred to as TN) mode, the contrast ratio and the viewing angle decrease as the number of dots in the dot matrix type liquid crystal display device increases.
In addition, in order to prevent the decrease of the contrast ratio and the viewing angle,
Twist the liquid crystal molecules by 90 degrees or more, and the included angle between the polarization axis of the polarizing plate and the molecular axis direction of the liquid crystal molecules adjacent to the electrode substrate is 30 degrees or less.
The super twisted nematic (hereinafter referred to as STN) type liquid crystal display device in the range of 60 degrees is different from the TN mode utilizing optical rotation and is a retardation mode utilizing optical interference. The STN type liquid crystal display device is unsuitable for color display because the difference in the non-application portion is caused by the difference in hue. Therefore, the present invention solves these problems, and an object thereof is to provide an optical anisotropic body having at least one color filter in addition to the nematic liquid crystal, to display the performance of the STN type liquid crystal display device as it is. It is to provide a color liquid crystal display device which can be effectively used.

[Means for solving problems]

The color liquid crystal display device of the present invention has two
A liquid crystal display device comprising a liquid crystal cell having a nematic liquid crystal twisted and oriented at more than 90 degrees between two electrode substrates, and a pair of polarizing plates arranged on both sides of the liquid crystal cell. A polymer film, which is an optically anisotropic body on which a color filter is formed, is disposed between the polarizing plate and the polarizing plate, and displays almost black when the display is off and the color of the color filter when the display is on. It is characterized by

〔Example〕

Embodiment 1 FIG. 1 is a modeled sectional view showing the structure of a color liquid crystal display device of the present invention. In the figure, 36 is an upper polarizing plate, 37 is an upper optically anisotropic body (hereinafter referred to as A layer), 38 is a liquid crystal cell (hereinafter referred to as B cell) for displaying by applying a voltage, 39 is a lower side. A layer, 40 is a lower polarizing plate, and 41 and 42 are color filters. Further, FIG. 2 is a view showing the relationship of each axis of the liquid crystal display device using the layer A. 45 in the figure
Is the rubbing direction of the upper electrode substrate of the B cell, 46 is the rubbing direction of the lower side of the B cell, 47 is the direction of the optical axis of the upper A layer, 48 is the direction of the optical axis of the lower A layer, and is the polarization of the upper polarizing plate. Axis (absorption axis)
, 50 is the direction of the absorption axis (polarization axis) of the lower polarizing plate, 51
Is the angle between the direction 49 of the polarization axis (absorption axis) of the upper polarizer and the optical axis 47 of the upper A layer, and 52 is the direction 47 of the optical axis of the upper A layer and B.
The angle formed by the rubbing direction 45 of the upper electrode substrate of the cell, 53
Is the size of the twist angle of the liquid crystal of the B cell, 54 is the sensitivity between the rubbing direction 46 of the lower electrode substrate of the B cell and the optical axis direction 48 of the lower A layer, and 55 is the optical axis of the lower A layer. The angle between the direction 48 and the direction 50 of the polarization axis (absorption axis) of the lower polarizing plate. In the figure, when the structure without the lower A layer is used, Δ of the upper A layer is
n × d is about 0.6 μm Angle 51 is about 50 degrees, Angle 52 is about 90 degrees
, The twist angle 53 of the liquid crystal molecules of the B cell is twisted to the left by about 200 degrees, and the angle formed by the rubbing direction 46 of the lower electrode substrate of the B cell and the absorption axis (polarization axis) direction 50 of the lower polarizing plate is formed. About 50 degrees, B
When a color filter is provided on the surface of the B cell side of the upper A layer of about 0.9 μm of the liquid crystal of the cell, the appearance color of the color liquid crystal display device is almost black in the OFF state and almost the same as the color filter in the ON state. Reproduced the color.

As layer A, DAC, PET, cellulose diacetate, PVA,
Uniaxially stretched film such as polyamide, polyether sulfone, acrylic, polysulfone, polyimide, or polyolefin is used. As the color filter provided in the layer A, dyeing, printing, film transfer or the like is used.

Example 2 In FIG. 2, the angle 51 is about 50 degrees, the angle 52 is about 90 degrees,
The twist angle 53 of the liquid crystal molecule of the B cell is a left twist of about 200 degrees,
The angle 54 is about 90 degrees and the angle 55 is about 50 degrees. Also, the upper side A
The sum of Δn × d of the layer and Δn × d of the lower A layer is about
0.6 μm, Δn × d of B cell is about 0.9 μm, and a color filter is printed on the surface of the upper A layer on the B cell side. Again,
It has the same effect as that of the first embodiment.

Example 3 In Example 2, the A layer itself is dyed. Alternatively, the pigment is dispersed in the A layer so that the A layer itself serves as a color filter. At this time, the same effect as that of the first embodiment is obtained.

〔The invention's effect〕

As described above, according to the present invention, color display with high contrast can be performed even if the display capacity is increased. In addition, since the color filter is formed on the polymer film, the structure is simplified.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating a model of the liquid crystal display device of the present invention. 36 …… Upper polarizing plate 37 …… Upper A layer 38 …… B cell 39 …… Lower A layer 40 …… Lower polarizing plate 41 …… Color filter on the upper A layer surface 42 …… On the lower A layer surface Color filter 33 ... B-cell upper electrode substrate 34 ... B-cell liquid crystal 35 ... B-cell lower electrode substrate FIG. 2 is a diagram showing the relationship of each axis of the liquid crystal display device of the present invention. In the figure, 45 is the rubbing direction of the upper electrode substrate of the B cell, 46 is the rubbing direction of the lower electrode substrate of the B cell, and 47.
Is the direction of the optical axis of the upper A layer, 48 is the direction of the optical axis of the lower A layer, 49 is the direction of the polarization axis (absorption axis) of the upper polarizing plate, and 50 is the absorption (polarization axis) of the lower polarizing plate. Direction, 51 is the angle between the direction of the polarization axis (absorption axis) of the upper polarizing plate and the direction of the optical axis of the upper A layer, 52 is the direction of the optical axis of the upper A layer, and 52 of the upper electrode substrate of the B cell The angle formed by the rubbing direction, 53 is the size of the twist angle of the liquid crystal molecules of the B cell, 54 is the angle formed by the rubbing direction of the lower electrode substrate of the B cell and the optical axis direction of the lower A layer,
Reference numeral 55 denotes the angle formed by the direction of the optical axis of the lower A layer and the direction of the absorption axis (polarization axis) of the lower polarizing plate.

Claims (1)

(57) [Claims] 1. A liquid crystal cell in which a nematic liquid crystal twisted and oriented at more than 90 degrees is sandwiched between two electrode substrates arranged opposite to each other, and a pair of polarized lights disposed on both sides of the liquid crystal cell. In a liquid crystal display device composed of a plate, a polymer film, which is an optically anisotropic body with a color filter formed, is disposed between the liquid crystal cell and the polarizing plate, and when the display is off, almost black is displayed. A color liquid crystal display device displaying the color of the color filter in an on state.