TWI412845B - Optical compensated bend type lcd - Google Patents

Abstract

An optical compensated bend mode LCD comprises a pixel electrode, a color filter, a common electrode and a liquid crystal layer. The pixel electrode is formed on the first substrate of the optical compensated bend (OCB) mode LCD. The color filter is formed on the second substrate of the OCB mode LCD. The common electrode is formed on the surface of the color filter. The liquid crystal layer is disposed between the pixel electrode and the common electrode. The second substrate has a step structure on its surface for twisting the liquid crystal in the splay state into the bend state uniformly and quickly.

Description

Optically compensated curved liquid crystal display

The present invention relates to an optically compensated bend (OCB) mode liquid crystal display (OCB mode LCD), and more particularly to a display panel capable of accelerating the transition of liquid crystal molecules from a splay state to a bend state.

LCD monitors are widely used in personal digital assistants (PDAs), notebook computers, digital cameras, video cameras, mobile phones, and other electronic products because of their advantages of thinness, power saving, and no radiation. . Coupled with the industry's active investment in research and development and the use of large-scale production equipment, the quality of liquid crystal displays continues to increase, and prices continue to decline, making the application field of liquid crystal displays rapidly expand.

In order to further increase the reaction rate of the liquid crystal layer and widen the viewing angle, in the current liquid crystal display production, three main improvement methods are designed for the material properties of the liquid crystal molecules. These three improvements include: (1) liquid crystal mode using Vertical Alignment (VA); (2) development of low viscosity liquid crystal molecules; and (3) optical compensation bending (OCB) mode.

The vertical alignment method is to change the surface shape of the alignment film so that the liquid crystal molecules are arranged along the surface of the alignment film, so that when a voltage is applied to the pixel electrode, the liquid crystal molecules can be rapidly rotated to be presented. Vertical arrangement. The way to develop low-viscosity liquid crystal materials is to focus on the liquid crystal reaction time and the viscosity of liquid crystal molecules in a proportional relationship; when the viscosity of liquid crystal molecules is reduced, the reaction time will be shortened.

For the liquid crystal display using the OCB mode, the liquid crystal molecules distributed on the upper and lower glass substrates are aligned in parallel, but the liquid crystal molecules in the inner layer are not twisted, but are arranged in a plane, and the arrangement causes light to be generated. The birefringence is such that the Biaxial Retardation Film can compensate for the phase difference in each axial direction and overcome the influence of the change in the optical characteristics caused by the tilt of the liquid crystal molecules, thereby providing a wide viewing angle. In addition, since the liquid crystal molecules in the OCB mode are only curved and arranged, it is not necessary to overcome the backflow delay of changing the twist arrangement like the liquid crystal molecules of the TN mode, so the OCB mode can reduce the reaction time of the liquid crystal display. It is much shorter than the response time of the traditional TN liquid crystal mode (about 50 ms) to 1~10 ms.

It is worth noting that although the OCB mode liquid crystal display has the above advantages, there are still many defects in application. For example, existing OCB mode liquid crystal displays often require a long warm-up time to switch the liquid crystal molecules in the liquid crystal layer from a splay state to a bent state in which operation is actually to be performed. Referring to the first A diagram and the first B diagram, the arrangement of the liquid crystal molecules 10 in the oblique state and the curved state is respectively shown. When a predetermined voltage is applied between the common electrode 12 and the pixel electrode 14, the liquid crystal molecules 10 are driven from the initial oblique state shown in the first A-picture, and twisted to form the first B-picture. Bending state for display.

In order to accelerate the transition of the liquid crystal molecules from the oblique state to the curved state, in the current OCB mode liquid crystal display design, a high voltage is applied between the common electrode 12 and the pixel electrode 14 at both ends of the liquid crystal layer to accelerate the rotation of the liquid crystal molecules. However, this method does not uniformly and quickly bring the liquid crystal molecules in the entire display panel to the desired bending state immediately. In this case, the display still does not display the image properly.

Moreover, in order to generate a large voltage across the pixel electrode 12 and the common electrode 14, it is necessary to change the high-voltage process specification of the driving chip of the display panel, or change the pattern design of the entire pixel, resulting in overall cost and design. The difficulty increases. Therefore, designers or manufacturers in this field are trying to provide an easy-to-produce display panel design to accelerate the transition of the liquid crystal molecules of the OCB mode liquid crystal display from the oblique state to the curved state. The direction.

To this end, the present invention provides an optically compensated bend (OCB) type liquid crystal display in which liquid crystal molecules can be rapidly transferred from a tilted state to a bent state for image display operations.

The optically compensated curved liquid crystal display comprises a pixel electrode, a color filter, a common electrode and a liquid crystal layer. The pixel electrode is fabricated on the first substrate of the optically compensated curved liquid crystal display. The color filter is fabricated on the second substrate of the optically compensated curved liquid crystal display and is vertically opposed to the pixel electrode. The common electrode is fabricated on the surface of the color filter.

The liquid crystal layer is located between the pixel electrode and the common electrode. When an electric field is generated between the pixel electrode and the common electrode, the liquid crystal molecules in the liquid crystal layer are affected by the electric field, and are arranged to be bent by the initial oblique state through twisting. status.

It should be noted that the surface of the second substrate is provided with a stepped structure. By the arrangement of the stepped structure, the liquid crystal molecules can be held in an approximately twisted state in an initial state, that is, an alignment direction with the alignment film. Moreover, the stepped structure also affects the electric field distribution in the pixel unit, so that the liquid crystal molecules are affected by the electric field after the change, and have a pretilt angle.

Therefore, when an electric field is generated between the pixel electrode and the common electrode, the liquid crystal molecules in the liquid crystal layer can be twisted to a curved state uniformly and rapidly from the oblique state.

To further clarify the above and other advantages of the present invention, the drawings are described in detail below.

Please refer to the second figure, which is a cross-sectional view of a first embodiment of an optically compensated bend (OCB) type liquid crystal display 2. The liquid crystal display 2 is formed by vertically stacking the first substrate 20 and the second substrate 21, and a liquid crystal layer L is sandwiched between the first substrate 20 and the second substrate 21. The optically compensated curved liquid crystal display 2 further includes a pixel electrode 22, a color filter 23, and a common electrode 24.

As shown in the second figure, the pixel electrode 22 is formed on the first substrate of the optically compensated curved liquid crystal display. In a general case, components such as a scan line, a data line, a thin film transistor, a common line, and the like are disposed on the first substrate 20, and the thin film transistor is turned on or off according to the electrical signal input by the scan line. The voltage signal on the data line is applied to the pixel electrode 22.

The color filter 23 is formed on the second substrate 21 of the optically compensated curved liquid crystal display, and is opposed to the above-described pixel electrode 22.

The common electrode 24 is formed on the surface of the color filter 23. When an electric field is generated between the pixel electrode 22 and the common electrode 24, the liquid crystal molecules in the liquid crystal layer L are affected by the electric field, and are twisted by the initial oblique state to be aligned.

It is to be noted that the surface of the second substrate 21 has a stepped structure S. By the arrangement of the stepped structure S, the liquid crystal molecules adjacent to the stepped structure S in the liquid crystal layer L can be affected by the stepped structure S, and the initial state of the liquid crystal molecules can be maintained in an oblique state which is easy to be quickly twisted. In addition, by mutual pushing between the liquid crystal molecules, the alignment state of the liquid crystal molecules adjacent to the stepped structure S can be diffused into the entire liquid crystal layer L, so that each liquid crystal molecule in the entire liquid crystal layer L is kept fast and easy. In the twisted state; when an electric field is formed between the pixel electrode 22 and the common electrode 24, the liquid crystal molecules in the liquid crystal layer L can be twisted to a curved state uniformly and rapidly from the oblique state.

The above-described stepped structure S will be further explained below. Referring to FIG. 3A and FIG. 3B together, a top view of the second substrate and a cross-sectional view along the line A-A' in the third A are respectively illustrated according to the present invention.

As shown in FIG. B, a black matrix (BM) 25 is formed over the second substrate 21, and a color filter 23 is formed over the black matrix 25 such that the black matrix 25 is located on the second substrate 21 and color. Between the filters 23. The common electrode 24 is formed on the color filter 23.

A bump 26 is provided on the surface of the common electrode 24. In the preferred embodiment, the distribution pattern of the protrusions 26 is as shown in the top view of FIG. A, which is distributed in the zigzag pattern 26a along the surface of the common electrode 24, and forms a step on the surface of the common electrode 24. Shape structure S (third B picture). The protrusions 26 may be made of an organic material or the like.

With the above structure, the liquid crystal molecules distributed around the periphery of the protrusion 26 can be arranged along the surface shape of the protrusion 26, and the initial state of the liquid crystal molecules can be maintained in an oblique state which is easy to be quickly twisted; at the same time, the state can be diffused. In the entire liquid crystal layer, the liquid crystal molecules in the entire liquid crystal layer are maintained in a state of being easily twisted quickly, thereby shortening the time during which the liquid crystal molecules are switched from the oblique state to the curved state.

It should be noted that the manner of distributing the stepped structure S formed by the protrusions 26 is not limited to the aforementioned zigzag pattern 26a. For example, the arrangement of the stepped structures S formed by the protrusions 26 may also be as shown in FIG. 3C, wherein the protrusions 26 are distributed along the plurality of segments of the continuous pattern 26b and extend along the common electrode 24. On the surface. It should be noted that although the multi-segmented continuous pattern 26b in the third C-picture is shown as a multi-segmented tooth-shaped bending pattern in a right angle, the embodiment of the present invention actually covers a multi-segmented bending pattern that is not a right-angled shape or Single-segment pattern.

The fourth A is a plan view of the second substrate in the second embodiment of the optical compensation bending (OCB) type liquid crystal display of the present invention. Figure 4B is a cross-sectional view of the second substrate in the aforementioned fourth A diagram taken along line A-A'.

In general, the color filter 23 has a plurality of color resistors (for example, a red color resistance, a green color resistance, and a blue color resistance), and filters the light into a desired color light by color resistance of different colors. Display color images. In the present embodiment, the stepped structure S is constituted by at least two adjacent color resists 23a, 23b overlapping each other. Specifically, a black matrix 25 is formed on the second substrate 21, and a color resist 23a and a color resist 23b are sequentially formed on the black matrix 25 to be stacked in a stepped structure S. In the present embodiment, the color resist 23b is superposed on the upper side of the color resist 23a, and the side of the color resist 23b has a zigzag pattern distribution.

As shown in FIG. 4B, a common electrode 24 is additionally formed on the stepped structure S. In a preferred embodiment, the common electrode 24 above the stepped structure S can form a conformal structure with the stepped structure S.

Fig. 5A is a plan view showing a second substrate of the third embodiment of the optical compensation bending (OCB) type liquid crystal display of the present invention. Fig. 5B is a cross-sectional view of the second substrate in the aforementioned fifth A diagram taken along the line A-A'.

As described above, the color filter includes a plurality of color resists, at least one of which has an opening pattern 23c to constitute a stepped structure S. As shown in FIG. 4B, after the color resist is formed on the black matrix 25, it can be dug out of the opening pattern 23c to expose the surface of the portion of the black matrix 25. Then, a common electrode 24 is fabricated thereon.

In the embodiment shown in FIG. A, the opening pattern 23c distributed over the color resist 23 is a zigzag pattern 23c1. In other embodiments, the opening pattern 23c distributed on the color resist 23 may be a tooth pattern 23c2 as shown in FIG.

It should be noted that although the opening patterns shown in the third A diagram, the third C diagram, the fourth A diagram, the fifth A diagram, and the fifth C diagram are continuous tooth-shaped or zigzag patterns, embodiments of the present invention It includes a non-continuous pattern and the shape is not limited to a tooth or a zigzag shape.

As can be seen from the above embodiments, the optically compensated bending (OCB) type liquid crystal display of the present invention maintains the initial alignment state of the liquid crystal molecules therein in a rapidly twistable state by having a stepped structure therein; When an electric field is generated between the common electrode and the pixel electrode, the liquid crystal molecules can be quickly and uniformly twisted and bent from the oblique state to perform image display operation, and the heat compensation of the optical compensation bending (OCB) type liquid crystal display can be greatly shortened. time. In addition, according to the present invention, it is possible to easily produce a stepped structure without greatly changing the original process, and thus has a high practical value.

The present invention has been described in detail by reference to the various embodiments of the present invention, which are not intended to limit the scope of the present invention, and it is obvious to those skilled in the art that the modifications may be made without departing from the spirit and scope of the invention.

10. . . Liquid crystal molecule

12. . . Common electrode

14. . . Pixel electrode

20. . . First substrate

twenty one. . . Second substrate

twenty two. . . Pixel electrode

twenty three. . . Color filter

23a. . . Color resistance

23b. . . Color resistance

23C. . . Opening pattern

23C1. . . Jagged pattern

23C2. . . Continuous tooth pattern

twenty four. . . Common electrode

25. . . Black matrix

26. . . Protrusion

26a. . . Jagged pattern

26b. . . Continuous tooth pattern

S. . . Stepped structure

L. . . Liquid crystal layer

The first A picture and the first B picture respectively show the arrangement of the liquid crystal molecules in the oblique state and the curved state in the optical compensation bending (OCB) type liquid crystal display.

The second figure is a cross-sectional view of a first embodiment of an optically compensated bend (OCB) type liquid crystal display.

3A and 3B are respectively a plan view of the second substrate in the first embodiment of the present invention, and a cross-sectional view taken along line A-A' in the third A diagram.

The third C diagram shows a pattern in which the stepped structures of the present invention are distributed on the second substrate.

4A and 4B are respectively a top plan view of the second substrate in the second embodiment of the present invention, and a cross-sectional view taken along line A-A' in the fourth A diagram.

5A and 5B are respectively a plan view of the second substrate in the second embodiment of the present invention, and a cross-sectional view taken along line A-A' in the fifth A diagram.

The fifth C diagram shows another pattern in which the stepped structure of the present invention is distributed on the second substrate.

twenty three. . . Color filter

twenty four. . . Common electrode

25. . . Black matrix

26a. . . Jagged pattern

Claims (4)

An optical compensation bending (OCB) type liquid crystal display comprising: a first substrate; a second substrate; a pixel electrode formed on the first substrate; a black matrix formed on the second substrate; a color filter a chip is formed on the second substrate and partially overlaps the black matrix, wherein the color filter has a plurality of color resistors, and one of the color resists has an opening pattern, and the opening pattern is located in the black Above the matrix, the opening pattern is a zigzag pattern; a common electrode is formed on the surface of the color filter; and a liquid crystal layer is located between the pixel electrode and the common electrode. An optically compensated curved liquid crystal display according to claim 1, wherein the opening pattern exposes a portion of the surface of the black matrix. An optically compensated curved liquid crystal display according to claim 1, wherein the opening pattern is a continuous tooth pattern. The optically compensated curved liquid crystal display of claim 1, wherein the common electrode located above the opening pattern forms a conformal structure with the opening pattern.