JPH0230488B2 - EKISHOHYOJISOCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a color display liquid crystal display device in which colors are differentiated by display area.

Conventional technology In order to divide the display surface of one liquid crystal display cell into two colors, conventionally, two types of color polarizing plates were pasted together, or half of one polarizing plate was covered with a green polarizing plate. Therefore, I had no choice but to make and use a multicolor polarizing plate with the other half as a red polarizing plate. In other words, a neutral polarizing plate is placed on the front side of a twisted nematic liquid crystal cell, and one of the above polarizing plates is attached on the back side to display two or more different colors.In one display cell, the background color is, for example, half red. So the other half is green.

In such conventional technology, there are drawbacks such as it takes time and effort to match two types of color polarizing plates, and making a multi-color polarizing plate is expensive. The drawback was that it did not produce deep colors.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a color liquid crystal display device that performs color separation according to the display area based on a principle completely different from the conventional color display method described above.

Structure of the Invention This invention involves partially changing the thickness of one twisted nematic liquid crystal cell, overlapping neutral polarizing plates on both sides of the cell with their polarization axes at a constant angle, and further providing a reflecting plate. In this case, differences in color due to light interference occur due to differences in cell thickness.

Twisted nematic liquid crystal cells produce interference colors, but conventionally this interferes with the display, so interference is achieved by arranging a polarizing plate so that its polarization axis is parallel or at 90 degrees to the cell orientation direction. It made the color less noticeable.

In contrast, in the present invention, color display is performed using interference colors in a twisted nematic liquid crystal cell. In order to produce interference colors, it is necessary to orient the polarization axes of the neutral polarizing plates stacked on the front and back sides of the liquid crystal cell in a certain direction with respect to the cell. As a result of the experiment, the polarization axis of one polarizing plate was oriented within a range of 45°±10° from the cell orientation direction, and the polarizing axis of the other polarizing plate was oriented within a range of 0°±10° with respect to the polarizing axis of the polarizing plate.
It was found that it is sufficient to aim within the range of 20° or 90° ± 20°. In order to produce interference colors, it is necessary not only to regulate the relationship between the cell and the polarizing plate, but also to control the cell thickness. As a result of experiments with various cell thicknesses, it was confirmed that interference colors appeared clearly when the cell thickness was in the range of 10.5μ to 11.7μ and in the range of 12.3μ to 13.2μ. Moreover, these two thickness ranges exhibit completely opposite colors. In other words, the cell thickness is
In the range of 10.5μ to 11.7μ, a green color appears when the polarization axes of the two polarizing plates are parallel to each other, and a reddish-purple color appears when the polarization axes intersect at 90°. When the cell thickness was 12.3μ to 13.2μ, a reddish-purple color was exhibited when the polarization axes were parallel to each other, and a green color was exhibited when the polarization axes were crossed at 90°. Even if the parallel or intersecting relationship between the two polarizing plates mentioned above was shifted within a range of +20°, the same coloration was obtained. In addition,
Cell thickness between the above two cell thickness ranges, i.e.
There was no coloration in the range from more than 11.7μ to less than 12.3μ.
Next, we investigated the allowable range of cell thickness unevenness in a single liquid crystal cell, and found that it was easy to see if the cell thickness unevenness within the display surface was within 0.7 μm.
If the unevenness exceeds this range, the same color may have different densities, resulting in poor display quality. Therefore, since the allowable range of the cell gap is narrower than that of a normal twisted nematic liquid crystal cell, it is necessary to reduce the unevenness of the cell gap within the display surface, which requires consideration in the process such as distributing highly accurate spacers. . As described above, two colors can be produced by the difference in cell thickness, so in the present invention, portions having the two cell thicknesses described above are provided within the display surface of one cell. In other words, the cell thickness within the display surface is 10.5μ to 11.7μ in some parts, and in other parts.
It should be in the range of 12.3μ to 13.2μ. Hundreds of glass fiber powders are sprinkled per ¹ cm2 as a gap holding material for the glass substrate of liquid crystal cells, but in order to vary the cell thickness within the same cell, two types of powder are prepared and dispersed partially. Spread each powder while wearing a mask.

Example 1 A glass substrate 1 with outer dimensions of 140 mm x 65 mm is partially masked, and glass fibers 2 with a diameter of 10 microns are placed in the upper half, and glass fibers 3 with a diameter of 11 microns are placed in the lower half, each in number per ¹ cm2. 100 pieces were distributed. Another glass substrate 4 was stacked and a twisted nematic liquid crystal cell 5 was assembled using a well-known method. When we investigated the cell thickness of this cell 5, the upper half part was 10.8μm±0.2μm, and the lower half part was 10.8μm±0.2μm.
It was 11.9μm±0.2μm. A neutral polarizing plate 6 was stacked on the front surface of the cell 5, with its polarization axis 6a tilted at 45 degrees with respect to the orientation direction 5a of the cell. A neutral polarizing plate 7 was also stacked on the back side of the cell 5 so that its polarizing axis 7a was parallel to the polarizing axis 6a of the polarizing plate 6. A white reflective plate 8 was further placed on the back side of this polarizing plate 7 to form a liquid crystal display device.

When no voltage was applied to this display device, the upper half exhibited a bright dark green color, and the lower half exhibited a bright reddish-purple color. The area where voltage is applied becomes discolored. The coloration of the faded portion varies depending on the strength of the applied voltage, but it can be displayed in a bright color compared to the dark green or reddish purple of the background.

Example 2 We created a display device with the same configuration as Example 1, but with the polarization axes of the two polarizing plates perpendicular to each other. took on a dark green color.

Specific ways to use the display device of the above embodiment include displaying two times on different ground colors in the upper and lower rows as shown in Figure 3, or displaying instruments as shown in Figure 4, Or as shown in Figure 5,
For example, the hours and minutes can be displayed on a green background, and the seconds can be displayed on a reddish-purple background.

Effects According to the present invention configured as described above, a liquid crystal display device having partially different color backgrounds within the same display surface can be obtained at low cost.

[Brief explanation of drawings]

The drawings show embodiments of the present invention; FIG. 1 is a cross-sectional view of a liquid crystal cell, FIG. 2 is a developed perspective view of a liquid crystal display device, and FIGS. 3 to 5 each show display examples. 5... Twisted nematic liquid crystal cell, 5a... Orientation direction, 6... Polarizing plate, 6a... Polarizing axis, 7... Polarizing plate, 7a... Polarizing axis, 8... Reflecting plate.

Claims (1)

[Claims] 1 Within the display surface, a portion where the cell thickness is within the range of 10.5μ to 11.5μ and where the unevenness of the cell thickness is within 0.7μ,
Within the range of 12.3μ to 13.2μ and the cell thickness unevenness is 0.7μ
a twisted nematic liquid crystal cell having a portion within 100 degrees, and a neutral polarizing plate stacked on the front and back sides of the liquid crystal cell, the polarization axis of one polarizing plate being 45°±10° with respect to the orientation direction of the cell. , and the other polarizing plate is arranged so that its polarizing axis is within a range of 0° ± 20° or 90° ± 20° with respect to the polarizing axis of the polarizing plate, and A liquid crystal display device including a reflective plate provided on the back side of a neutral polarizing plate.