CN1316300C - Coplanar converting LCD with video response - Google Patents

Abstract

The invention discloses a coplanar conversion liquid crystal display with video response, which belongs to the liquid crystal display technology. The liquid crystal display includes a liquid crystal cell, a pair of 1/4 broadband wave plates and a pair of polarizers; when the dielectric anisotropy of the liquid crystal material is positive, the twist angle is 180°, and the rubbing direction is perpendicular to the electric field direction, 1 /4 The angle between the optical axis of the broadband wave plate and the optical axis of the polarizer is 45°, and the direction of the optical axis of the polarizer is perpendicular to the rubbing direction of the substrate or parallel to the rubbing direction of the substrate; when the dielectric anisotropy of the liquid crystal material When it is negative, the twist angle is 180°, the friction direction is parallel to the direction of the electric field, the angle between the optical axis of the 1/4 broadband wave plate and the optical axis of the polarizer is 45°, and the direction of the optical axis of the polarizer is perpendicular to the substrate The rubbing direction of or parallel to the rubbing direction of the substrate. The liquid crystal display of the invention can realize bright display and dark display in a wide viewing angle range, has high contrast ratio and fast response speed, and meets the requirements of video display.

Description

Coplanar Switching LCD Displays with Video Response

technical field

The invention relates to a liquid crystal display, in particular to a coplanar switching liquid crystal display with video response.

Background technique

The traditional coplanar switching liquid crystal display adopts a liquid crystal arrangement structure arranged in parallel. These liquid crystal displays all include a liquid crystal cell with a liquid crystal layer. The liquid crystal molecules are arranged in parallel at a specific angle in a liquid crystal cell composed of a pair of transparent glass substrates. A comb-shaped electrode is formed on one of the glass substrates, and a pair of clamps are also included. The polarizer of the liquid crystal cell.

Although the traditional coplanar switching liquid crystal display has good viewing angle characteristics, its response speed is relatively slow, and it is not suitable for the application of LCD TVs that require video response. More specifically, the response speed of the coplanar switching liquid crystal display is related to the thickness of the liquid crystal layer, the rotational viscosity coefficient and twist elastic constant of the liquid crystal, and the arrangement form of the liquid crystal molecules in the cell. The liquid crystal molecules of the traditional coplanar switching liquid crystal display are arranged in parallel, which leads to the response speed of this display mode being small due to the small twist elastic constant, and the response speed proportional to its reciprocal is difficult to improve, and by reducing the thickness of the liquid crystal layer (production The minimum thickness that the process can bear) and the improvement of the rotational viscosity coefficient of the liquid crystal material cannot make the response speed of each gray level reach the video response.

Contents of the invention

The object of the present invention is to provide a coplanar switching liquid crystal display with video response. The liquid crystal display can realize bright display and dark display in a wide viewing angle range, and has high contrast ratio.

The present invention is achieved through the following technical solutions, a coplanar switching liquid crystal display with video response, comprising a liquid crystal box, a pair of 1/4 broadband wave plates and a pair of polarizers; the liquid crystal box is A pair of opposing glass substrates, an alignment layer formed on the inner surface of the glass substrates, a liquid crystal layer between the two glass substrates, and a comb-shaped electrode formed on one of the substrates form an electric field in the X-axis direction, and the electrode spacing is greater than the electrode width and The thickness of the liquid crystal layer; the outer sides of the two glass substrates are sequentially a 1/4 broadband wave plate and a polarizer. When the dielectric anisotropy of the liquid crystal material is positive, it is characterized in that the twist angle in the liquid crystal layer is 180°, and the friction The direction is perpendicular to the direction of the electric field, the staggered angle between the optical axis of the 1/4 broadband wave plate and the optical axis of the polarizer is 45°, the optical axes of the two 1/4 broadband wave plates are parallel to each other, and the optical axes of the two polarizers The optical axes are parallel to each other, and the direction of the optical axis of the polarizer is parallel to the rubbing direction on the substrate, that is, the direction of the optical axis of the polarizer is perpendicular to the direction of the electric field.

A coplanar switching liquid crystal display with video response, comprising a liquid crystal cell, a pair of 1/4 broadband wave plates and a pair of polarizers; the liquid crystal cell is a pair of opposite glass substrates, the inner surface of the glass substrate The alignment layer formed, the liquid crystal layer between the two glass substrates, and a comb-shaped electrode formed on one of the substrates form an electric field in the X-axis direction, and the electrode spacing is greater than the electrode width and the thickness of the liquid crystal layer; the outer sides of the two glass substrates are 1 /4 broadband wave plate and polarizer, when the dielectric anisotropy of the liquid crystal material is positive, it is characterized in that the twist angle in the liquid crystal layer is 180°, the friction direction is perpendicular to the direction of the electric field, and the 1/4 broadband wave The staggered angle between the optical axis of the plate and the optical axis of the polarizer is 45°, the optical axes of the two 1/4 broadband wave plates are parallel to each other, the optical axes of the two polarizers are parallel to each other, and the direction of the optical axis of the polarizer is vertical The rubbing direction on the substrate, that is, the direction of the optical axis of the polarizer is parallel to the direction of the electric field.

A coplanar switching liquid crystal display with video response, comprising a liquid crystal cell, a pair of 1/4 broadband wave plates and a pair of polarizers; the liquid crystal cell is a pair of opposite glass substrates, the inner surface of the glass substrate The alignment layer formed, the liquid crystal layer between the two glass substrates, and a comb-shaped electrode formed on one of the substrates form an electric field in the X-axis direction, and the electrode spacing is greater than the electrode width and the thickness of the liquid crystal layer; the outer sides of the two glass substrates are 1 /4 broadband wave plate and polarizer, when the dielectric anisotropy of the liquid crystal material is negative, it is characterized in that the twist angle in the liquid crystal layer is 180°, the rubbing direction is parallel to the direction of the electric field, and the 1/4 broadband wave The staggered angle between the optical axis of the plate and the optical axis of the polarizer is 45°, the optical axes of the two 1/4 broadband wave plates are parallel to each other, the optical axes of the two polarizers are parallel to each other, and the direction of the optical axis of the polarizer is vertical The rubbing direction on the substrate, that is, the direction of the optical axis of the polarizer is perpendicular to the direction of the electric field.

A coplanar switching liquid crystal display with video response, comprising a liquid crystal cell, a pair of 1/4 broadband wave plates and a pair of polarizers; the liquid crystal cell is a pair of opposite glass substrates, the inner surface of the glass substrate The alignment layer formed, the liquid crystal layer between the two glass substrates, and a comb-shaped electrode formed on one of the substrates form an electric field in the X-axis direction, and the electrode spacing is greater than the electrode width and the thickness of the liquid crystal layer; the outer sides of the two glass substrates are 1 /4 broadband wave plate and polarizer, when the dielectric anisotropy of the liquid crystal material is negative, it is characterized in that the twist angle in the liquid crystal layer is 180°, the rubbing direction is parallel to the direction of the electric field, and the 1/4 broadband wave The staggered angle between the optical axis of the plate and the optical axis of the polarizer is 45°, the optical axes of the two 1/4 broadband wave plates are parallel to each other, the optical axes of the two polarizers are parallel to each other, and the directions of the optical axes of the polarizer are parallel The rubbing direction on the substrate, that is, the direction of the optical axis of the polarizer is parallel to the direction of the electric field.

The above-mentioned display is characterized in that the thickness of the liquid crystal layer is 2-6 microns, and the value of the product Δnd of the birefringence Δn and the thickness d of the liquid crystal layer is 240-330 nm.

Advantages and effects of the present invention: According to the display mode provided by the present invention, when a voltage is applied to the electrodes sandwiching the liquid crystal layer, the liquid crystal molecules rotate in the plane of the glass substrate, so that the optical axis of the liquid crystal layer changes, thereby changing the optical axis passing through the liquid crystal layer. After the polarization state of the light, the light transmittance of the liquid crystal cell changes with the applied voltage by the configuration of two 1/4 broadband wave plates and polarizers. Because the liquid crystal molecules rotate in the plane of the glass substrate, the retardation of the liquid crystal layer under different voltages changes little with the viewing angle. Therefore, the liquid crystal display of the present invention can realize bright display and dark display in a wide viewing angle range, and obtain high contrast ratio in a wide viewing angle range.

In the present invention, the liquid crystal cell has a super-twisted liquid crystal layer sandwiched by the substrate. The upper and lower parts of the liquid crystal layer have antisymmetry, and the liquid crystal molecules in the middle layer remain motionless under the action of the electric field, which is equivalent to the entire liquid crystal layer. It can be considered to be composed of two liquid crystal layers with upper and lower fixed boundaries, and the layer thickness is halved, so the response speed of the liquid crystal cell is faster than that of the traditional parallel liquid crystal cell (including the rising speed and falling speed). On the premise of using common liquid crystal materials for TFT, fast response speed can be obtained only by improving the alignment structure of liquid crystal molecules.

The following narration and specified means and combinations thereof will also reflect the purpose and advantages of the present invention.

Description of drawings

FIG. 1 shows a perspective view of an exploded structure of a liquid crystal display according to Embodiment 1 of the present invention;

2 is a partial cross-sectional view of a liquid crystal display;

Fig. 3 is the view of the viewing angle range of the liquid crystal display shown in Fig. 1;

Fig. 4 is the response time figure of eight gray scales of the liquid crystal display shown in Fig. 1;

FIG. 5 shows a perspective view of an exploded structure of a liquid crystal display according to Embodiment 2 of the present invention;

6 shows a perspective view of an exploded structure of a liquid crystal display according to Embodiment 3 of the present invention;

Figure 7 shows a perspective view of an exploded structure of a liquid crystal display according to Embodiment 4 of the present invention

Detailed ways

The liquid crystal display according to the embodiment of the present invention will be described below with reference to the accompanying drawings.

[first embodiment]

1 to 4 show a first embodiment of the present invention. FIG. 1 is a perspective view of an exploded structure of a liquid crystal display, and FIG. 2 is a partial cross-sectional view of a liquid crystal display.

As shown in Figures 1 and 2, the liquid crystal display of the present embodiment sandwiches the liquid crystal layer 1 between the relative two glass substrates 2 and 3 inner layers, and a 1/4 broadband wave plate 5 is respectively arranged on the two outer sides of the glass substrates. Its outside is a polarizer 6, and the inner surface of the lower glass substrate 3 is provided with a comb-shaped electrode 4. The signals on the comb electrodes 4a, 4b are provided by TFTs (Thin Film Transistors) (not shown). Alignment layers 7 are provided on the inner surfaces of the glass substrates 2 and 3 respectively, and the liquid crystal material can be aligned in a predetermined direction through rubbing treatment.

The liquid crystal display of this embodiment is an STN type liquid crystal display. By rubbing the alignment layer on the inner surface of the glass substrates 2, 3 and pouring a suitable liquid crystal material (positive dielectric anisotropy), it has a 180° twist 1 . The optical axes of the two polarizers are parallel to the orientation of the liquid crystal molecules on the surface of the adjacent alignment layer, and the optical axes of the two 1/4 broadband wave plates intersect with the optical axes of the polarizers at an angle of 45° and are parallel to each other.

When there is no voltage difference between the comb-shaped electrodes, the liquid crystal layer mainly behaves as an optical rotator and a phase retarder, and the polarization state of the light passing through the liquid crystal layer changes slightly, so when there is no voltage action, this embodiment shows light through. When a small voltage difference exists, this embodiment can show a black state, and when a larger voltage difference exists, the liquid crystal molecules in the liquid crystal layer tend to align along the direction of the electric field 1a, and the liquid crystal layer only shows a phase retardation plate, the angle relationship between the optical axis shown by the liquid crystal layer and the optical axis of the 1/4 broadband wave plate 5 and the polarizer 6, this embodiment shows a bright state under the action of a larger voltage difference, so This embodiment can be displayed as a display.

Because the liquid crystal molecules in the liquid crystal layer rotate along the plane of the glass substrate, the liquid crystal display with the above layout can obtain high display contrast ratio in a wide viewing angle. As shown in FIG. 3 , the calculation result of the viewing angle characteristics of a specific example of this embodiment is shown. Its viewing angle range exceeds 60° up and down, and the left and right range exceeds 85° (contrast ratio greater than 5).

Because this embodiment uses the super twisted alignment structure of liquid crystal molecules, the liquid crystal layer has the antisymmetry of the upper and lower parts under the action of the electric field, and the liquid crystal molecules in the middle layer remain still, which is equivalent to that the liquid crystal layer can be considered to be composed of two parts. There are upper and lower fixed boundaries and a liquid crystal layer whose layer thickness is halved, so the response speed of this embodiment is a quarter of that of the original parallel liquid crystal layer, so it has a faster response speed than the traditional coplanar switching liquid crystal display ( including ascent and descent speeds). As shown in FIG. 4 , the calculation result of the dynamic response time of a specific example of this embodiment (the thickness of the liquid crystal layer in this example is 4 μm). The figure shows the rising and falling process of the 8 grayscale display in this example, the falling time is about 6 milliseconds, and the rising time is less than 12 milliseconds (response time when the transmittance is 1/8 of the maximum transmittance). Because the response time of the liquid crystal layer is proportional to the square of the thickness of the liquid crystal layer, appropriately reducing the thickness of the liquid crystal layer (in industrial production can be reduced to 3 μm, in the laboratory can be reduced to 2 μm) can make the rise time less than 10 milliseconds, and at the same time The fall time is also reduced so that the sum of the rise and fall times can be less than 16 milliseconds, enabling full grayscale video response.

[Second embodiment]

FIG. 5 is a perspective view of an exploded structure of a liquid crystal display according to a second embodiment of the present invention. The difference between this liquid crystal display and the liquid crystal display of the first embodiment is that the directions of the optical axes of the polarizers are different. . Its working principle is the same as that of the first embodiment, and has the same characteristics as the first embodiment.

[Third embodiment]

6 is a perspective view of an exploded structure of a liquid crystal display according to a third embodiment of the present invention. The difference between this liquid crystal display and the liquid crystal display of the first embodiment is that the liquid crystal used is a material with negative dielectric anisotropy and the rubbing direction is different. Liquid crystal molecules tend to be arranged in a direction perpendicular to the direction of the electric field under the action of an electric field, so the rubbing direction is required to be perpendicular to the rubbing direction of the first embodiment. Its working principle is the same as that of the first embodiment, and it has the same features characteristic.

[Fourth Embodiment]

7 is a perspective view of an exploded structure of a liquid crystal display according to a fourth embodiment of the present invention. The difference between this liquid crystal display and the liquid crystal display of the third embodiment is that the directions of the optical axes of the polarizers are different. In this embodiment, the optical axes of the two polarizers are parallel to the direction of the liquid crystal molecules on the adjacent glass substrate surface. Its working principle is the same as that of the third embodiment, and has the same characteristics as the third embodiment.

Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader limitations is not limited to the specific details and various embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit and scope of the general principles of the invention as defined by the appended claims and their equivalents.

Claims (5)

1, a kind of coplanar converting LCD with video response comprises a liquid crystal cell, a pair of 1/4 broadband wave plate and a pair of polaroid; Described liquid crystal cell is a pair of relative glass substrate, the oriented layer that the inside surface of glass substrate forms, the liquid crystal layer between two glass substrates, and be shaped on comb electrode on the plate base therein, form the X-direction electric field, electrode separation is greater than electrode width and thickness of liquid crystal layer; The outside of two glass substrates is 1/4 broadband wave plate and polaroid successively, when the dielectric anisotropy of liquid crystal material is timing, it is characterized in that, distortion angle in the liquid crystal layer is 180 °, frictional direction is perpendicular to direction of an electric field, staggered angle between the optical axis of 1/4 broadband wave plate and the optical axis of polaroid is 45 °, the optical axis of two 1/4 broadband wave plates is parallel to each other, the optical axis of two polaroids is parallel to each other, the optical axis direction of polaroid is parallel to the frictional direction on the substrate, and promptly the optical axis direction of polaroid is perpendicular to direction of an electric field.

2. the coplanar converting LCD with video response comprises a liquid crystal cell, a pair of 1/4 broadband wave plate and a pair of polaroid; Described liquid crystal cell is a pair of relative glass substrate, the oriented layer that the inside surface of glass substrate forms, the liquid crystal layer between two glass substrates, and be shaped on comb electrode on the plate base therein, form the X-direction electric field, electrode separation is greater than electrode width and thickness of liquid crystal layer; The outside of two glass substrates is 1/4 broadband wave plate and polaroid successively, when the dielectric anisotropy of liquid crystal material is timing, it is characterized in that, distortion angle in the liquid crystal layer is 180 °, frictional direction is perpendicular to direction of an electric field, staggered angle between the optical axis of 1/4 broadband wave plate and the optical axis of polaroid is 45 °, the optical axis of two 1/4 broadband wave plates is parallel to each other, the optical axis of two polaroids is parallel to each other, the optical axis direction of polaroid is perpendicular to the frictional direction on the substrate, and promptly the optical axis direction of polaroid is parallel to direction of an electric field.

3. the coplanar converting LCD with video response comprises a liquid crystal cell, a pair of 1/4 broadband wave plate and a pair of polaroid; Described liquid crystal cell is a pair of relative glass substrate, the oriented layer that the inside surface of glass substrate forms, the liquid crystal layer between two glass substrates, and be shaped on comb electrode on the plate base therein, form the X-direction electric field, electrode separation is greater than electrode width and thickness of liquid crystal layer; The outside of two glass substrates is 1/4 broadband wave plate and polaroid successively, when the dielectric anisotropy of liquid crystal material when negative, it is characterized in that, distortion angle in the liquid crystal layer is 180 °, frictional direction is parallel to direction of an electric field, staggered angle between the optical axis of 1/4 broadband wave plate and the optical axis of polaroid is 45 °, the optical axis of two 1/4 broadband wave plates is parallel to each other, the optical axis of two polaroids is parallel to each other, the optical axis direction of polaroid is perpendicular to the frictional direction on the substrate, and promptly the optical axis direction of polaroid is perpendicular to direction of an electric field.

4. the coplanar converting LCD with video response comprises a liquid crystal cell, a pair of 1/4 broadband wave plate and a pair of polaroid; Described liquid crystal cell is a pair of relative glass substrate, the oriented layer that the inside surface of glass substrate forms, the liquid crystal layer between two glass substrates, and be shaped on comb electrode on the plate base therein, form the X-direction electric field, electrode separation is greater than electrode width and thickness of liquid crystal layer; The outside of two glass substrates is 1/4 broadband wave plate and polaroid successively, when the dielectric anisotropy of liquid crystal material when negative, it is characterized in that, distortion angle in the liquid crystal layer is 180 °, frictional direction is parallel to direction of an electric field, staggered angle between the optical axis of 1/4 broadband wave plate and the optical axis of polaroid is 45 °, the optical axis of two 1/4 broadband wave plates is parallel to each other, the optical axis of two polaroids is parallel to each other, the optical axis direction of polaroid is parallel to the frictional direction on the substrate, and promptly the optical axis direction of polaroid is parallel to direction of an electric field.

5. as claim 1 or 2 or 3 or 4 described coplanar converting LCDs with video response, it is characterized in that thickness of liquid crystal layer is 2～6 microns, the long-pending Δ nd value of birefraction and thickness of liquid crystal layer d is in 240～330nm.

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