CN108490696B

CN108490696B - Liquid crystal display device and visual angle switching method thereof

Info

Publication number: CN108490696B
Application number: CN201810450787.XA
Authority: CN
Inventors: 姜丽梅; 苏子芳; 赵哲; 刘瑞
Original assignee: InfoVision Optoelectronics Kunshan Co Ltd
Current assignee: InfoVision Optoelectronics Kunshan Co Ltd
Priority date: 2018-05-11
Filing date: 2018-05-11
Publication date: 2021-03-23
Anticipated expiration: 2038-05-11
Also published as: CN108490696A

Abstract

The utility model provides a liquid crystal display device, including first base plate and second base plate, be equipped with visual angle control electrode on the first base plate, be provided with common electrode on the second base plate, be limited by scanning line and data line and form a plurality of pixels on the second base plate, every pixel includes main pixel, first sub-pixel and second sub-pixel, be equipped with the main pixel electrode including a plurality of pixel electrode strip in every main pixel, be equipped with first sub-pixel electrode in every first sub-pixel, be equipped with the second sub-pixel electrode in every second sub-pixel. According to the invention, the vertical electric field is formed in the area of the corresponding pixel part between the first substrate and the second substrate, so that liquid crystal molecules in the liquid crystal layer are deflected under the action of the vertical electric field, and the visual angle of the liquid crystal display device in the left-right direction and/or the up-down direction is reduced, thereby realizing free switching between a wide visual angle and a narrow visual angle in the up-down direction and/or the left-right direction.

Description

Liquid crystal display device and visual angle switching method thereof

Technical Field

The present invention relates to the field of display technologies, and in particular, to a liquid crystal display device and a method for switching viewing angles thereof.

Background

A Liquid Crystal Display (LCD) has advantages of good picture quality, small size, light weight, low driving voltage, low power consumption, no radiation, and relatively low manufacturing cost, and is dominant in the field of flat panel displays.

With the continuous progress of the liquid crystal display technology, the viewing angle of the display has been widened from about 120 ° to over 160 °, and people want to effectively protect business confidentiality and personal privacy while enjoying visual experience brought by a large viewing angle, so as to avoid business loss or embarrassment caused by the leakage of screen information.

The current display device gradually develops towards the direction of wide viewing angle, and no matter the application of mobile phone terminal, desktop display or notebook computer, besides the requirement of wide viewing angle, in many occasions, the display device is also required to have the function of switching between wide viewing angle and narrow viewing angle. At present, there are several ways to switch between a wide viewing angle and a narrow viewing angle of a liquid crystal display device.

The first is realized by attaching a shutter shielding film on the display screen, and when peep prevention is needed, the view angle can be reduced by shielding the screen by the shutter shielding film. However, in this method, an extra louver film is required to be prepared, which causes great inconvenience to a user, and one louver film can only realize one viewing angle, and once the louver film is attached, the viewing angle is fixed, and only a narrow viewing angle mode can be realized, and the wide viewing angle function cannot be displayed.

The second is to arrange a dual light source backlight system in the lcd device for adjusting the viewing angle of the lcd device, the dual light source backlight system is composed of two stacked light guide plates combined with an inverse prism sheet, the top light guide plate (LGP-T) combined with the inverse prism sheet changes the direction of the light so that the light is limited in a relatively narrow angular range, thereby realizing the narrow viewing angle of the lcd device, while the bottom light guide plate (LGP-B) combined with the inverse prism sheet functions to realize the wide viewing angle of the lcd device. However, such a dual-light source backlight system increases the thickness and cost of the liquid crystal display device, and is not suitable for the trend of thinning the liquid crystal display device.

The third is to apply a vertical electric field to the liquid crystal molecules by using a viewing angle control electrode on one side of a color filter substrate (CF), thereby realizing a narrow viewing angle mode. However, this method can only switch the wide and narrow viewing angles in the left-right direction, and cannot simultaneously switch the wide and narrow viewing angles in the left-right direction and/or the up-down direction.

Disclosure of Invention

The invention aims to provide a liquid crystal display device, which solves the problem that the conventional liquid crystal display device can only realize the switching of wide and narrow visual angles in the left and right directions.

The technical problem to be solved by the invention is realized by adopting the following technical scheme.

The invention provides a liquid crystal display device, which comprises a first substrate, a second substrate and a liquid crystal layer positioned between the first substrate and the second substrate, wherein a visual angle control electrode is arranged on the first substrate, a common electrode is arranged on the second substrate, a plurality of sub-pixels are formed on the second substrate in a limiting way through scanning lines and data lines, each sub-pixel comprises a main pixel, a first sub-pixel and a second sub-pixel, the alignment direction of liquid crystal molecules in the first sub-pixel is vertical to that of liquid crystal molecules in the second sub-pixel, and the liquid crystal molecules in the main pixel are in a flat lying state under different visual angle modes; a main pixel electrode comprising a plurality of pixel electrode strips is arranged in each main pixel, a first sub-pixel electrode is arranged in each first sub-pixel, and a second sub-pixel electrode is arranged in each second sub-pixel.

Further, the first electrode portion includes a plurality of electrically connected first conductive strips, the second electrode portion includes a plurality of electrically connected second conductive strips, and the third electrode portion includes a plurality of electrically connected third conductive strips.

Furthermore, the viewing angle control electrode comprises a second electrode part and a third electrode part which are insulated from each other, the second electrode part correspondingly covers the first sub-pixel, and the third electrode part correspondingly covers the second sub-pixel.

Further, the areas of the first sub-pixel electrode and the second sub-pixel electrode are equal.

Further, the liquid crystal layer uses negative liquid crystal molecules, the alignment of the negative liquid crystal molecules corresponding to each main pixel extends along the direction of the scanning line, the alignment of the negative liquid crystal molecules corresponding to each first sub-pixel extends along the direction of the scanning line, and the alignment of the negative liquid crystal molecules corresponding to each second sub-pixel extends along the direction of the data line.

A viewing angle switching method of a liquid crystal display device as described above, the viewing angle switching method comprising:

in a first viewing angle mode, a reference common voltage is applied to the common electrode on the second substrate, and a first voltage signal with a smaller voltage difference relative to the reference common voltage is applied to the second electrode part and the third electrode part of the viewing angle control electrode on the first substrate, so that the voltage difference between the common electrode and the viewing angle control electrode is smaller than a preset value, and liquid crystal molecules in a region corresponding to the main pixel are in a lying state.

In a second viewing angle mode, a reference common voltage is applied to the common electrode on the second substrate, and a second voltage signal with a larger voltage difference relative to the reference common voltage is applied to the second electrode part and the third electrode part of the viewing angle control electrode on the first substrate, so that the voltage difference between the common electrode and the viewing angle control electrode is larger than a preset value, and the liquid crystal molecules in the region corresponding to the main pixel are in a lying state.

Further, in the first viewing angle mode, the first voltage signal applied to the viewing angle control electrode is the same as the reference common voltage applied to the common electrode, so that the voltage difference between the common electrode and the viewing angle control electrode is zero; in a second viewing angle mode, the second voltage signal applied to the viewing angle control electrode is an alternating voltage, so that the voltage difference between the common electrode and the viewing angle control electrode is greater than zero.

The invention provides a liquid crystal display device, wherein a visual angle control electrode for controlling a visual angle is arranged on a first substrate, each sub-pixel comprises a main pixel, a first sub-pixel and a second sub-pixel, the alignment directions of liquid crystal molecules in the first sub-pixel and the second sub-pixel are mutually vertical, a visual angle control voltage is applied to the visual angle control electrode, on the premise of keeping the liquid crystal molecules of the main pixel in a lying state, a voltage difference is generated between the visual angle control electrode and a common electrode, vertical electric fields are respectively formed in the corresponding areas of a plurality of pixel parts between the two substrates, the liquid crystal molecules in a liquid crystal layer are deflected under the action of the vertical electric fields, and the visual angle adjustment of the liquid crystal display device in the left-right direction and/or the up-down direction is realized.

Drawings

Fig. 1 is a schematic plan view of a liquid crystal display device according to a first embodiment of the present invention.

Fig. 2 is a partial structural schematic diagram of fig. 1.

Fig. 3 is a schematic structural diagram of the viewing angle control electrode in fig. 1.

Fig. 4 is an exploded view of fig. 1.

Fig. 5a to 5d are schematic diagrams illustrating the arrangement of the negative liquid crystal molecules in fig. 2 when different voltages are applied to the viewing angle control electrodes.

FIG. 6 is a schematic plan view of a liquid crystal display device according to a second embodiment of the present invention.

Fig. 7 is an exploded view of fig. 6.

Fig. 8a to 8d are schematic diagrams illustrating the arrangement of the positive liquid crystal molecules in fig. 6 when different voltages are applied to the viewing angle control electrodes.

FIG. 9 is a partial cross-sectional view of a liquid crystal display device in a third embodiment of the present invention.

Detailed Description

To further illustrate the technical means and effects of the present invention adopted to achieve the predetermined objects, the following detailed description of the embodiments, structures, features and effects of the present invention will be made with reference to the accompanying drawings and examples.

[ first embodiment ]

Fig. 1 is a schematic plan view of a liquid crystal display device according to a first embodiment of the present invention, fig. 2 is a schematic partial view of fig. 1, fig. 3 is a schematic view of a viewing angle control electrode of fig. 1, and fig. 4 is a schematic exploded view of fig. 1. Referring to fig. 1 to 4, the lcd device includes a first substrate 21, a second substrate 22 disposed opposite to the first substrate 21, and a liquid crystal layer 23 disposed between the first substrate 21 and the second substrate 22.

The liquid crystal display device according to the present embodiment is suitable for use in a liquid crystal display device of an in-plane switching (IPS) mode, a Fringe Field Switching (FFS) mode, or the like, in which the common electrode and the pixel electrode are formed on the same substrate (that is, a thin film transistor array substrate), and when an electric field for display is applied between the common electrode and the pixel electrode, liquid crystal molecules rotate in a plane substantially parallel to the substrate to obtain a wide viewing angle. In this embodiment, the liquid crystal display device will be described by taking a Fringe Field Switching (FFS) mode as an example.

Referring to fig. 4, the first substrate 21 is, for example, a color filter substrate, and the second substrate 22 is, for example, a thin film transistor array substrate. The first substrate 21 is provided with a first polarizer 211 at a side facing away from the liquid crystal layer 23, the second substrate 22 is provided with a second polarizer 221 at a side facing away from the liquid crystal layer 23, and a transmission axis X1 of the first polarizer 211 is perpendicular to a transmission axis X2 of the second polarizer 221.

Fig. 5a to 5d are schematic diagrams illustrating the arrangement of the negative liquid crystal molecules in fig. 3 when different voltages are applied to the viewing angle control electrodes. Referring to fig. 1 to 4 and 5a to 5d, the first substrate 21 has a viewing angle control electrode 212 on a side facing the liquid crystal layer 23, and the second substrate 22 has a scan line 222, a data line 223, a Thin Film Transistor (TFT)224, a common electrode 225, an insulating layer 226 and a pixel electrode 227 on a side facing the liquid crystal layer 23.

Wherein the plurality of scan lines 222 and the plurality of data lines 223 cross each other to define a plurality of sub-pixels distributed in an array. In this embodiment, each sub-pixel is, for example, a red (R), green (G), and blue (B) sub-pixel, and a plurality of adjacent sub-pixels constitute one pixel P for display. For example, one pixel may include three sub-pixels of red (R), green (G), and blue (B), but the present invention is not limited thereto.

In the present embodiment, each pixel includes three sub-pixels, that is, each pixel includes a main pixel SP1, a first sub-pixel SP2, and a second sub-pixel SP 3. Wherein a main pixel electrode 227a is provided in the main pixel SP1, a first sub-pixel electrode 227b is provided in each of the second sub-pixels SP2, and a second sub-pixel electrode 227c is provided in each of the second sub-pixels SP 3; the first thin film transistor 224a is disposed in the main pixel SP1, the second thin film transistor 224b is disposed in the first sub-pixel SP2, and the third thin film transistor 224c is disposed in the second sub-pixel SP 3.

Preferably, in the present embodiment, the areas of the first sub-pixel electrode 227b and the second sub-pixel electrode 227c may be equal, and specifically, the first sub-pixel electrode 227b and the second sub-pixel electrode 227c are both planar electrodes, for example. Correspondingly, the pixel aperture areas of the first sub-pixel SP2 and the second sub-pixel SP3 are equal, but the sum of the pixel aperture areas of the first sub-pixel SP2 and the second sub-pixel SP3 is not greater than the pixel aperture area of the main pixel SP 1. In other embodiments, the first sub-pixel electrode 227b and the second sub-pixel electrode 227c may be slit electrodes.

Referring to fig. 1 and 2, the tfts (224a, 224b, 224c) are located near the intersection of the scan line 222 and the data line 223. The thin film transistors (224a, 224b, 224c) are electrically connected to the corresponding scan lines 222, data lines 223 and electrodes. Each thin film transistor (224a, 224b, 224c) includes a gate electrode electrically connected to the corresponding scan line 222, a semiconductor layer, a source electrode and a drain electrode (not shown), the source electrode and the drain electrode are spaced apart from each other and are in contact with the semiconductor layer, one of the source electrode and the drain electrode is electrically connected to the corresponding data line 223, and one of the source electrode and the drain electrode is electrically connected to the corresponding electrode.

Referring to fig. 1, the main pixel electrode 227a includes a plurality of first pixel electrode bars 2271 spaced apart from each other, and a first slit 2273 is formed between adjacent first pixel electrode bars 2271.

Referring to fig. 1 and 2, the liquid crystal layer 23 employs negative liquid crystal molecules, the alignment of the negative liquid crystal molecules corresponding to each main pixel SP1 extends along the direction of the scan line 222, the alignment of the negative liquid crystal molecules corresponding to each first sub-pixel SP2 extends along the direction of the scan line 222, and the alignment of the negative liquid crystal molecules corresponding to each second sub-pixel SP3 extends along the direction of the data line 223.

Referring to fig. 2 and fig. 3, in the present embodiment, the sub-pixels are respectively arranged in rows along the directions of the scan lines 222 and the data lines 223.

The viewing angle control electrode 212, the common electrode 225 and the pixel electrode 227 can be made of transparent conductive materials such as Indium Tin Oxide (ITO) and Indium Zinc Oxide (IZO) as transparent electrodes. The viewing angle control electrode 212 is used to control the viewing angle switching. The common electrode 225 is used for applying a common voltage for screen display. The pixel electrode 227 is used for receiving a data signal to control the display of a picture.

In this embodiment, the pixel electrode 227 is located above the common electrode 225, and the insulating layer 226 is disposed therebetween, but the invention is not limited thereto, and in other embodiments, the pixel electrode 227 may also be located below the common electrode 225. In addition, when the liquid crystal display device employs an in-plane switching (IPS) mode, the common electrode 225 and the pixel electrode 227 may also be located in the same layer and insulated and spaced apart from each other, such as the common electrode 225 and the pixel electrode 227.

Referring to fig. 3 and 4, in the present embodiment, the viewing angle control electrode 212 includes a first electrode portion 212a, a second electrode portion 212b and a third electrode portion 212c, which are insulated from each other, the first electrode portion 212a covers the main pixel SP1, the second electrode portion 212b covers the first sub-pixel SP2, and the third electrode portion 212c covers the second sub-pixel SP 3. Since the liquid crystal molecules corresponding to the main pixel SP1 are always in a lying state at any viewing angle, in other embodiments, the viewing angle control electrode 212 may include only the second electrode portion 212b and the third electrode portion 212c insulated from each other, and the region of the viewing angle control electrode 212 corresponding to the main pixel SP1 may not be provided with an electrode portion.

Referring to fig. 3 and fig. 4, in the present embodiment, the liquid crystal molecules in the liquid crystal layer 23 are negative liquid crystal molecules. The alignment direction of the position on the first substrate 21 corresponding to each main pixel SP1 is a1, the alignment direction of the position on the first substrate 21 corresponding to each first sub-pixel SP2 is a2, and the alignment direction of the position on the first substrate 21 corresponding to each second sub-pixel SP3 is A3; the alignment direction of the position on the second substrate 22 corresponding to each main pixel SP1 is B1, the alignment direction of the position on the second substrate 22 corresponding to each first sub-pixel SP2 is B2, and the alignment direction of the position on the second substrate 22 corresponding to each second sub-pixel SP3 is B3. The liquid crystal molecules in the liquid crystal layer 23 are aligned along the alignment directions on the first and

second substrates

21 and 22, and the initial alignment directions of the liquid crystal molecules in the first and second sub-pixels SP2 and SP3 are perpendicular to each other.

The present embodiment may align the first and

second substrates

21 and 22, respectively, by photo-alignment, which may be achieved by aligning the main pixel SP1, the first sub-pixel SP2, and the second sub-pixel SP3, respectively, using a mask or the like. In other embodiments, the main pixel SP1, the first sub-pixel SP2 and the second sub-pixel SP3 may be aligned separately by rubbing the sub-region alignment.

Further, the alignment direction a1 on the first substrate 21 is parallel or antiparallel (antiparallel in the present embodiment) to the alignment direction B1 on the second substrate 22 corresponding to each main pixel SP 1; the alignment direction a2 on the first substrate 21 is parallel or antiparallel (antiparallel in the present embodiment) to the alignment direction B2 on the second substrate 22 corresponding to each first subpixel SP 2; the alignment direction A3 on the first substrate 21 is parallel or antiparallel (antiparallel in the present embodiment) to the alignment direction B3 on the second substrate 22 corresponding to each of the second sub-pixels SP 3.

By applying a voltage to the viewing angle control electrode 212, different voltage differences can be generated between the viewing angle control electrode 212 and the common electrode 225, so that the liquid crystal display device can be switched between a wide viewing angle mode and a narrow viewing angle mode, as shown in fig. 5a to 5 d.

Referring to fig. 5a, in the initial state of the lcd device without any voltage applied, the negative liquid crystal molecules in the region of each main pixel SP1 are set to have a low pretilt angle, i.e. the negative liquid crystal molecules in the region are in a state close to lying when in the initial state; the liquid crystal molecules located in the region of each first sub-pixel SP2 and the negative liquid crystal molecules located in the region of each second sub-pixel SP3 are both disposed at a high pretilt angle, i.e., the negative liquid crystal molecules in the two regions are in a tilted state in an initial state. In this case, the liquid crystal display device has a narrow viewing angle in both the left-right direction and the up-down direction.

Referring to fig. 5b, when a voltage for display is applied to the pixel electrode 227, a voltage difference is not applied or a small voltage difference is applied between the first electrode portion 212a and the third electrode portion 212c and the common electrode 225, and a voltage difference of a certain magnitude is applied between the second electrode portion 212b and the common electrode 225, a vertical electric field (as shown by an arrow E in the figure) is formed in a region between the two

substrates

21 and 22 corresponding to each first sub-pixel SP2, and since the long axis direction of the negative liquid crystal molecules tends to rotate along a direction perpendicular to the electric field line under the action of the electric field, the negative liquid crystal molecules in each first sub-pixel SP2 are deflected under the action of the vertical electric field, and the tilt angle between the negative liquid crystal molecules and the first substrate 21 and the second substrate 22 is reduced, and the negative liquid crystal molecules are deflected from the tilted posture to the lying posture. The negative liquid crystal molecules in each of the first sub-pixels SP2 are deflected by the vertical electric field to make the viewing angle of the liquid crystal display device in the left-right direction smaller, so that the liquid crystal display device is switched to a wide viewing angle in the left-right direction, and at this time, the liquid crystal display device has a narrow viewing angle in the up-down direction.

Referring to fig. 5c, when a voltage for display is applied to the pixel electrode 227, a voltage difference is not applied or a small voltage difference is applied between the first electrode portion 212a and the second electrode portion 212b and the common electrode 225, and a voltage difference of a certain magnitude is applied between the third electrode portion 212c and the common electrode 225, a vertical electric field (as shown by an arrow E in the figure) is formed between the two

substrates

21 and 22 corresponding to each second sub-pixel SP3, and since the long axis direction of the negative liquid crystal molecules tends to rotate along the direction perpendicular to the electric field line under the action of the electric field, the negative liquid crystal molecules in each second sub-pixel SP3 are deflected under the action of the vertical electric field, and the tilt angle between the negative liquid crystal molecules and the first substrate 21 and the second substrate 22 is reduced, and the negative liquid crystal molecules are deflected from the tilted posture to the lying posture. The negative liquid crystal molecules in each of the second sub-pixels SP3 are deflected by the vertical electric field, so that the viewing angle of the liquid crystal display device increases in the vertical direction, and the liquid crystal display device is switched to a wide viewing angle in the vertical direction, and at this time, the liquid crystal display device has a narrow viewing angle in the left-right direction.

Referring to fig. 5d, when a voltage for displaying is applied to the pixel electrode 227, a voltage difference is not applied or a small voltage difference is applied between the first electrode portion 212a and the common electrode 225, and a voltage difference of a certain magnitude is applied between the second electrode portion 212b, the third electrode portion 212c and the common electrode 225, a vertical electric field (as shown by an arrow E in the figure) is formed between the two

substrates

21 and 22 corresponding to each of the first sub-pixel SP2 and the second sub-pixel SP3, and since the long axis direction of the negative liquid crystal molecules tends to rotate along the direction parallel to the electric field lines under the action of the electric field, the negative liquid crystal molecules in each of the first sub-pixel SP2 and the second sub-pixel SP3 are deflected under the action of the vertical electric field, and the tilt angle between the negative liquid crystal molecules and the first substrate 21 and the second substrate 22 is reduced, and the negative liquid crystal molecules are deflected from the tilted posture to. The negative liquid crystal molecules in each of the first sub-pixel SP2 and the second sub-pixel SP3 are deflected by the vertical electric field, so that the viewing angle of the liquid crystal display device is increased in both the left-right direction and the up-down direction, and the liquid crystal display device is switched to a wide viewing angle in both the left-right direction and the up-down direction.

In this embodiment, the voltage output to the common electrode 225 is a DC common voltage (i.e., DC Vcom), and the voltage output to the viewing angle control electrode 212 is a periodic alternating voltage that fluctuates up and down around the DC common voltage. The waveform of the ac voltage may be a square wave, a sine wave, a triangular wave, a sawtooth wave, or the like.

In order to apply voltage to the viewing angle control electrode 212 on the first substrate 21, in the peripheral non-display area of the liquid crystal display device, the viewing angle control electrode 212 is electrically conducted from the first substrate 21 to the second substrate 22 through a conductive adhesive (not shown), a driving chip (not shown) provides voltage to the second substrate 22, and the second substrate 22 applies voltage to the viewing angle control electrode 212 of the first substrate 21 through the conductive adhesive.

[ second embodiment ]

Fig. 6 is a schematic plan view showing a liquid crystal display device according to a second embodiment of the present invention, fig. 7 is a schematic exploded view of fig. 6, and fig. 8a to 8d are schematic arrangement views of positive liquid crystal molecules of fig. 6 when different voltages are applied to viewing angle control electrodes. The present embodiment is different from the first embodiment in that positive liquid crystal molecules are used for the liquid crystal layer 23 in the present embodiment.

Referring to fig. 6 and 7, the alignment direction of the position on the first substrate 21 corresponding to each main pixel SP1 is a1, the alignment direction of the position on the first substrate 21 corresponding to each first sub-pixel SP2 is a2, and the alignment direction of the position on the first substrate 21 corresponding to each second sub-pixel SP3 is A3; the alignment direction of the position on the second substrate 22 corresponding to each main pixel SP1 is B1, the alignment direction of the position on the second substrate 22 corresponding to each first sub-pixel SP2 is B2, and the alignment direction of the position on the second substrate 22 corresponding to each second sub-pixel SP3 is B3. The liquid crystal molecules in the liquid crystal layer 23 are aligned along the alignment directions on the first and

second substrates

The present embodiment may align the first and

second substrates

By applying a voltage to the viewing angle control electrode 212, different voltage differences can be generated between the viewing angle control electrode 212 and the common electrode 225, so that the liquid crystal display device can be switched between a wide viewing angle mode and a narrow viewing angle mode, as shown in fig. 8a to 8 d.

Referring to fig. 8a, in an initial state of the liquid crystal display device without any voltage applied, the positive liquid crystal molecules in the liquid crystal layer 23 are aligned along the alignment direction and assume a lying posture parallel to the first and

second substrates

21 and 22, wherein the liquid crystal molecules in each main pixel SP1 are aligned along the alignment directions a1 and B1, the liquid crystal molecules in each first sub-pixel SP2 are aligned along the alignment directions a2 and B2, and the liquid crystal molecules in each second sub-pixel SP3 are aligned along the alignment directions A3 and B3. The long axis direction of the positive liquid crystal molecules is substantially parallel to the surfaces of the first and

second substrates

21 and 22. In practical applications, the positive liquid crystal molecules in the liquid crystal layer 23 and the first and

second substrates

21 and 22 may have a small initial pretilt angle, which may range from less than or equal to 5 degrees, that is: 0 DEG ≦ theta ≦ 5 deg. At this time, since no display voltage is applied to the pixel electrode 227, the liquid crystal molecules do not rotate in a plane parallel to the first substrate 21 and the second substrate 22, and the liquid crystal display device assumes a black state.

Referring to fig. 8b, when a voltage for display is applied to the pixel electrode 227, a voltage difference is not applied or a small voltage difference is applied between the first electrode portion 212a and the third electrode portion 212c and the common electrode 225, and a voltage difference of a certain magnitude is applied between the second electrode portion 212b and the common electrode 225, a vertical electric field (as shown by an arrow E in the figure) is formed between the two

substrates

21 and 22 corresponding to each first sub-pixel SP2, and the positive liquid crystal molecules tend to rotate along a direction parallel to an electric field line in a long axis direction under the action of the electric field, so that the positive liquid crystal molecules in each first sub-pixel SP2 are deflected under the action of the vertical electric field, and an inclination angle between the positive liquid crystal molecules and the first substrate 21 and the second substrate 22 is increased, and the positive liquid crystal molecules are deflected from a lying posture to a tilted posture. The positive liquid crystal molecules in each of the first sub-pixels SP2 are deflected by the vertical electric field, so that the viewing angle of the liquid crystal display device in the up-down direction is decreased, and the liquid crystal display device is switched to a narrow viewing angle in the up-down direction.

Referring to fig. 8c, when a voltage for display is applied to the pixel electrode 227, a voltage difference is not applied or a small voltage difference is applied between the first electrode portion 212a and the second electrode portion 212b and the common electrode 225, and a voltage difference of a certain magnitude is applied between the third electrode portion 212c and the common electrode 225, a vertical electric field (as shown by an arrow E in the figure) is formed between the two

substrates

21 and 22 corresponding to each second sub-pixel SP3, and the positive liquid crystal molecules tend to rotate along a direction parallel to the electric field lines in the long axis direction under the action of the electric field, so that the positive liquid crystal molecules in each second sub-pixel SP3 are deflected under the action of the vertical electric field, and the tilt angle between the positive liquid crystal molecules and the first substrate 21 and the second substrate 22 increases, and the positive liquid crystal molecules are deflected from the lying posture to the tilted posture. The positive liquid crystal molecules in each of the second sub-pixels SP3 are deflected by the vertical electric field, so that the viewing angle of the liquid crystal display device is decreased in both left and right directions, thereby switching the liquid crystal display device to a narrow viewing angle in both left and right directions.

Referring to fig. 8d, when a voltage for display is applied to the pixel electrode 227, a voltage difference is not applied or a small voltage difference is applied between the first electrode portion 212a and the common electrode 225, and a voltage difference of a certain magnitude is applied between the second electrode portion 212b, the third electrode portion 212c and the common electrode 225, a vertical electric field (as shown by an arrow E in the figure) is formed between the two

substrates

21 and 22 corresponding to each of the first sub-pixel SP2 and the second sub-pixel SP3, and the positive liquid crystal molecules in each of the first sub-pixel SP2 and the second sub-pixel SP3 are deflected by the vertical electric field because the long axis direction of the positive liquid crystal molecules tends to rotate along a direction parallel to the electric field lines, so that the tilt angle between the positive liquid crystal molecules and the first substrate 21 and the second substrate SP3 is increased, and the positive liquid crystal molecules are deflected from the lying posture to the tilted posture. The positive liquid crystal molecules in each of the first sub-pixel SP2 and the second sub-pixel SP3 are deflected by the vertical electric field, so that the viewing angle of the liquid crystal display device is decreased in both the left-right direction and the up-down direction, and the liquid crystal display device is switched to a narrow viewing angle in both the left-right direction and the up-down direction.

[ third embodiment ]

FIG. 9 is a partial cross-sectional view of a liquid crystal display device in a third embodiment of the present invention. Referring to fig. 3, the present embodiment is different from the second embodiment in that a common electrode 225 is disposed on a region of the second substrate 22 corresponding to each of the main pixels SP1, and the common electrode 225 is not disposed on a region of the second substrate 22 corresponding to each of the first sub-pixels SP2 and the second sub-pixels SP 3. The present embodiment also includes other structures and elements, please refer to the second embodiment.

When a voltage for display is applied to the pixel electrode 227, a voltage difference is not applied or a small voltage difference is applied between the first electrode part 212a and the common electrode 225, and a voltage difference of a certain magnitude is applied between the second electrode part 212b, the third electrode part 212c and the pixel electrode 227, a vertical electric field is formed between the two

substrates

21 and 22 in a region corresponding to each of the first sub-pixel SP2 and the second sub-pixel SP3, so that the liquid crystal display device is switched to a narrow viewing angle in both the left-right direction and the up-down direction. Also, in this embodiment, in any viewing angle mode, the liquid crystal molecules in the region corresponding to each main pixel SP1 of the liquid crystal display device are in a lying state.

When no voltage difference or a small voltage difference is applied between the second electrode part 212b, the third electrode part 212c and the pixel electrode 227, the liquid crystal display device displays a full-width wide viewing angle.

When a voltage difference of a certain magnitude is applied only between the second electrode part 212b and the first sub-pixel electrode 227b or only between the third electrode part 212c and the second sub-pixel electrode 227c, the liquid crystal display device switches to a narrow viewing angle only in the up-down direction or only in the left-right direction.

The invention also provides a visual angle switching method of the liquid crystal display device, which comprises the following steps:

in the first viewing angle mode, a reference common voltage is applied to the common electrode 225 on the second substrate 22, and a first voltage signal having a small voltage difference with respect to the reference common voltage is applied to the second electrode part 212b and the third electrode part 212c of the viewing angle control electrode 212 on the first substrate 21, so that the voltage difference between the common electrode 225 and the viewing angle control electrode 212 is less than a preset value, and liquid crystal molecules of a region corresponding to the main pixel SP1 are in a lying state;

in the second viewing angle mode, a reference common voltage is applied to the common electrode 225 on the second substrate 22, and a second voltage signal having a large voltage difference with respect to the reference common voltage is applied to the second electrode part 212b and the third electrode part 212c of the viewing angle control electrode 212 on the first substrate 21, so that the voltage difference between the common electrode 225 and the viewing angle control electrode 212 is greater than a preset value, and the liquid crystal molecules of the region corresponding to the main pixel SP1 are in a lying state.

Further, in the first viewing angle mode, the first voltage signal applied to the viewing angle control electrode 212 is the same as the reference common voltage applied to the common electrode 225, so that the voltage difference between the common electrode 225 and the viewing angle control electrode 212 is zero; in the second viewing angle mode, the second voltage signal applied to the viewing angle control electrode 212 is an ac voltage, so that the voltage difference between the common electrode 225 and the viewing angle control electrode 212 is greater than zero.

Further, when the liquid crystal layer 30 employs positive liquid crystal molecules, the first viewing angle mode is a wide viewing angle mode, and the second viewing angle mode is a narrow viewing angle mode; when the liquid crystal layer 30 uses negative liquid crystal molecules, the first viewing angle mode is a narrow viewing angle mode, and the second viewing angle mode is a wide viewing angle mode.

The invention controls the voltage applied on the first electrode part 212a, the second electrode part 212b and the third electrode part 212c of the visual angle control electrode 212 to generate voltage differences with different sizes between each electrode part and the common electrode 225, forms vertical electric fields in corresponding different sub-pixel regions between the first substrate 21 and the second substrate 22, deflects liquid crystal molecules in the liquid crystal layer 23 under the action of the vertical electric fields, causes a light leakage phenomenon to occur to reduce the contrast of a screen, reduces the visual angle of the liquid crystal display device in the left-right direction and/or the up-down direction, realizes free switching between a wide visual angle and a narrow visual angle in the up-down direction and/or the left-right direction, and has stronger operation flexibility and convenience.

As used herein, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, including not only those elements listed, but also other elements not expressly listed.

In this document, the terms front, back, upper and lower are used to define the components in the drawings and the positions of the components relative to each other, and are used for clarity and convenience of the technical solution. It is to be understood that the use of the directional terms should not be taken to limit the scope of the claims.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. A liquid crystal display device, comprising a first substrate (21), a second substrate (22) and a liquid crystal layer (23) between the first substrate (21) and the second substrate (22), wherein a viewing angle control electrode (212) is disposed on the first substrate (21), a common electrode (225) is disposed on the second substrate (22), and a plurality of pixels (P) are defined by scanning lines (222) and data lines (223) on the second substrate (22), wherein each pixel (P) comprises a main pixel (SP 1), a first sub-pixel (SP 2) and a second sub-pixel (SP 3), the alignment direction of liquid crystal molecules in the first sub-pixel (SP 2) and the alignment direction of liquid crystal molecules in the second sub-pixel (SP 3) are perpendicular to each other, and the liquid crystal molecules in the main pixel (SP 1) are in a flat state under different viewing angle modes; a main pixel electrode (227 a) comprising a plurality of pixel electrode strips (2271) is arranged in each main pixel (SP 1), a first sub-pixel electrode (227 b) is arranged in each first sub-pixel (SP 2), a second sub-pixel electrode (227 c) is arranged in each second sub-pixel (SP 3), the viewing angle control electrode (212) comprises a second electrode part (212 b) and a third electrode part (212 c) which are insulated from each other, the second electrode part (212 b) correspondingly covers the first sub-pixel (SP 2), and the third electrode part (212 c) correspondingly covers the second sub-pixel (SP 3);

in a first viewing angle mode, applying a reference common voltage to the common electrode (225) on the second substrate (22), and applying a first voltage signal having a small voltage difference with respect to the reference common voltage to the second electrode portion (212 b) and the third electrode portion (212 c) of the viewing angle control electrode (212) on the first substrate (21), so that the voltage difference between the common electrode (225) and the viewing angle control electrode (212) is less than a preset value;

in a second viewing angle mode, applying a reference common voltage to the common electrode (225) on the second substrate (22), and applying a second voltage signal having a large voltage difference with respect to the reference common voltage to the second electrode part (212 b) and the third electrode part (212 c) of the viewing angle control electrode (212) on the first substrate (21), so that the voltage difference between the common electrode (225) and the viewing angle control electrode (212) is greater than a preset value; liquid crystal molecules located in the first sub-pixel (SP 2) and/or the second sub-pixel (SP 3) are deflected by a vertical electric field.

2. The liquid crystal display device according to claim 1, wherein the viewing angle control electrode (212) includes a first electrode portion (212 a), and the first electrode portion (212 a) correspondingly covers the main pixel (SP 1).

3. The lcd apparatus of claim 2, wherein the first electrode portion (212 a) comprises a plurality of electrically connected first conductive strips (2121), the second electrode portion (212 b) comprises a plurality of electrically connected second conductive strips (2122), and the third electrode portion (212 c) comprises a plurality of electrically connected third conductive strips (2123).

4. The liquid crystal display device according to claim 1, wherein the first sub-pixel electrode (227 b) and the second sub-pixel electrode (227 c) have the same area, the first sub-pixel (SP 2) and the second sub-pixel (SP 3) have the same pixel aperture area, and the sum of the pixel aperture areas of the first sub-pixel (SP 2) and the second sub-pixel (SP 3) is not more than the pixel aperture area of the main pixel (SP 1).

5. The liquid crystal display device according to claim 1, wherein the common electrode (225) is disposed on the second substrate (22) in a region corresponding to each main pixel (SP 1), each first sub-pixel (SP 2), and each second sub-pixel (SP 3).

6. The liquid crystal display device according to claim 1, wherein an alignment of liquid crystal molecules corresponding to each main pixel (SP 1) extends in a direction of the scan line (222), an alignment of liquid crystal molecules corresponding to each first sub-pixel (SP 2) extends in a direction of the scan line (222), and an alignment of liquid crystal molecules corresponding to each second sub-pixel (SP 3) extends in a direction of the data line (223).

7. The liquid crystal display device according to claim 1, wherein the common electrode (225) is provided on a region of the second substrate (22) corresponding to each main pixel (SP 1), and the common electrode (225) is not provided on a region of the second substrate (22) corresponding to each first sub-pixel (SP 2) and each second sub-pixel (SP 3).

8. A viewing angle switching method of a liquid crystal display device according to any one of claims 1 to 6, characterized in that the viewing angle switching method comprises:

in a first viewing angle mode, a reference common voltage is applied to a common electrode (225) on a second substrate (22), a first voltage signal having a small voltage difference with respect to the reference common voltage is applied to a second electrode part (212 b) and a third electrode part (212 c) of a viewing angle control electrode (212) on a first substrate (21), so that the voltage difference between the common electrode (225) and the viewing angle control electrode (212) is less than a preset value, and liquid crystal molecules of a region corresponding to a main pixel (SP 1) are in a lying state;

in a second viewing angle mode, a reference common voltage is applied to the common electrode (225) on the second substrate (22), and a second voltage signal having a large voltage difference with respect to the reference common voltage is applied to the second electrode portion (212 b) and the third electrode portion (212 c) of the viewing angle control electrode (212) on the first substrate (21), so that the voltage difference between the common electrode (225) and the viewing angle control electrode (212) is greater than a preset value, and liquid crystal molecules of a region corresponding to the main pixel (SP 1) are in a lying state.

9. The viewing angle switching method according to claim 8, wherein in the first viewing angle mode, a first voltage signal applied to the viewing angle control electrode (212) is the same as a reference common voltage applied to the common electrode (225), so that a voltage difference between the common electrode (225) and the viewing angle control electrode (212) is zero; in a second viewing angle mode, a second voltage signal applied to the viewing angle control electrode (212) is an alternating voltage, so that a voltage difference between the common electrode (225) and the viewing angle control electrode (212) is greater than zero.