JPH0784254A - Liquid crystal display element for wide visual field angle and high-speed display - Google Patents

Abstract

PURPOSE:To provide the liquid crystal display element for wide visual field angle and high speed display by subjecting liquid crystal molecules to bend orientation and combining a phase compensation plate. CONSTITUTION:A liquid crystal oriented cell 5 formed by reverse inclining the liquid crystal molecules 3 on the surfaces of upper and lower substrates is used. The liquid crystal makes bend orientation or attains the orientation that twist orientation exists in the central part of the cell when a certain voltage is applied to this cell 5. Further, the liquid crystal cell having such orientation is fast in a change of the liquid crystal with a change in the voltage. The driving voltage, however, increases extremely in this state and, therefore, the used phase compensation plate 4 is so designed as to optically compensate the orientation of the liquid crystal of the certain low voltage in such a case. Sufficient black is displayed with the driving voltage as low as about the voltage of the conventional TV type liquid crystal display element and the visual field angle is widened by adopting such constitution.

Description

Detailed Description of the Invention

[0001]

This device is used in general electronic display devices such as televisions and computer monitors.

[0002]

2. Description of the Related Art Currently, as a liquid crystal display device, a T shown in FIG.
N-type (twisted nematic type) liquid crystal display devices are widely used.

[0003]

In the conventional method, the brightness of the image changes greatly depending on the viewing direction. An example of this measurement is shown in FIG. As described above, there is a serious problem that the brightness of the image is inverted in some cases. For this reason,
Oblique viewing was not possible and the viewing angle was limited.

Further, the response speed is not sufficient, and particularly when the halftone is set to 0 to 7 levels as shown in FIG. 3 and the final state is 1 to 3 levels, the response becomes slow. For this reason, there is a disadvantage that a sufficient moving image cannot be obtained when displaying halftone.

It is an object of the present invention to solve both the problem of viewing angle dependence and the problem of response speed, which are important in a display device, and to realize a liquid crystal display device of wide viewing angle and high speed display.

[0006]

The problem of the viewing angle of the conventional liquid crystal display element has been caused by the change of the optical characteristics due to the difference of the incident direction of light. In order to solve this problem, a phase compensation plate may be added to cancel the change in the optical characteristics of the liquid crystal depending on the direction. However, T
In the N-type liquid crystal display element, since the liquid crystal molecules have a twisted orientation as shown in FIG. 1, the polarization characteristics become very complicated and it is almost impossible to perform compensation by the phase compensating plate.

On the other hand, in the present invention, the liquid crystal molecules are bend-aligned as shown in FIG. 4 to simplify the optical characteristics of the liquid crystal portion and facilitate the design of the necessary phase compensator. A wide viewing angle was realized by combining a phase compensator.

In order to realize such bend alignment, a liquid crystal alignment cell in which liquid crystal molecules on the upper and lower substrate surfaces are inclined in opposite directions is used. Then, when a certain voltage is applied to this cell, the liquid crystal has a bend orientation or an orientation in which a twisted orientation exists in the center of the cell. Since any of these orientations is almost the same electro-optically, it can be represented by a bend cell.

Further, in the liquid crystal cell having such an orientation, the change of liquid crystal with respect to the change of voltage is fast. Therefore, a high response speed can be realized by using this cell.
However, if it is left as it is, the driving voltage becomes very high. Therefore, the phase compensation plate used here is designed so as to optically compensate the alignment of the liquid crystal having a certain low voltage. By doing so, sufficient black can be displayed with a driving voltage as low as that of the conventional TN type liquid crystal display element.

Further, due to the symmetry of the bend alignment, the viewing angle in the plane direction in which the major axis of the liquid crystal molecule exists can be widened, and by using the phase compensator, the viewing angle in the orthogonal direction can be significantly widened. You can A schematic diagram of this configuration is shown in FIG.

[0011]

In order to obtain a high quality image, it is important to display sufficient black. By attaching a phase compensator to the bend cell, it is possible to compensate the optical characteristics of the liquid crystal at a certain voltage and create a black state with no angle dependence.
Therefore, by using the display element of the present invention, a liquid crystal display in which a high-quality image can be obtained from a wide range can be realized.

Further, in order to display a good moving image, the response speed needs to be 30 milliseconds. The conventional liquid crystal display device cannot be made because the response speed is insufficient. However, since the device of the present invention can obtain a sufficient response time, good display of moving images can be realized.

[0013]

EXAMPLE FIG. 6 shows the result of measuring the angle-dependent characteristics of a display device that was actually manufactured. From this, it can be confirmed that it is remarkably improved as compared with FIG. 2 showing the conventional characteristics. Moreover, the result of having measured the characteristic of response speed is shown in FIG. From this, it can be confirmed that the characteristics are remarkably improved as compared with the conventional characteristics shown in FIG.

[0014]

Since the present invention is constructed as described above, it has the following effects.

In the liquid crystal display, a display having a wide viewing angle can be realized by the conventional manufacturing process. Further, moving image display can be sufficiently realized on a television or a graphic image terminal that requires halftone display.

[Brief description of drawings]

FIG. 1 is a schematic view of alignment of liquid crystals in a conventional TN type liquid crystal display device.

FIG. 2 is a measurement result of viewing angle dependence of display of a conventional TN type liquid crystal display device.

FIG. 3 is a measurement result of a display speed of a conventional TN type liquid crystal display device.

FIG. 4 is a schematic view of alignment of liquid crystals used in a liquid crystal display device for wide viewing angle and high speed display.

FIG. 5 is a schematic view of a liquid crystal display device with a wide viewing angle and high speed display.

FIG. 6 shows the measurement results of the viewing angle dependence of a liquid crystal display element for wide viewing angle and high-speed display.

FIG. 7 is a measurement result of a display speed of a liquid crystal display device with a wide viewing angle and high-speed display.

[Explanation of symbols]

 1 Polarizer 2 Glass 3 Liquid Crystal Molecule 4 Phase Compensator 5 Bend Alignment Cell

Claims (3)

[Claims] 1. A liquid crystal display device using a bend-aligned liquid crystal cell including a liquid crystal cell having twisted alignment in the center of the cell, and a phase compensator for lowering drive voltage and viewing angle dependence. 2. A transmissive liquid crystal display device in which the cell and the phase compensator described in claim 1 are sandwiched by orthogonal polarizers, and a light source is attached behind them. 3. A reflection type liquid crystal display device comprising the cell and the phase compensation plate according to claim 1, wherein a polarizer is placed only in front and a reflector is placed behind.