CN101498869B - Visual angle controllable liquid crystal display device and driving method - Google Patents

Abstract

The invention relates to a liquid crystal display device with controllable viewing angle and a driving method thereof. The liquid crystal display device includes a first substrate and a second substrate oppositely arranged, signal lines and scanning lines arranged perpendicularly to each other formed on the first substrate, and a plurality of intersecting lines formed by the signal lines and the scanning lines. a pixel area, and a vertically aligned liquid crystal layer sandwiched between the first substrate and the second substrate, a pixel electrode is formed on the first substrate, and the second substrate is disposed on the second substrate to form the The first common electrode of the single-domain arrangement of the liquid crystal layer is provided, and the second common electrode for forming the multi-domain arrangement of the liquid crystal layer is arranged on the second substrate. The liquid crystal display device provided by the present invention can save the rubbing process for the alignment layer, thereby reducing the manufacturing cost, simplifying the process flow, and avoiding poor display of the liquid crystal display device caused by the rubbing process.

Description

Viewing Angle Controllable Liquid Crystal Display Device and Driving Method

technical field

The invention relates to a liquid crystal display device and a driving method thereof, in particular to a liquid crystal display device and a driving method thereof capable of controlling the viewing angle width.

Background technique

A liquid crystal display (LCD) has gradually become one of the fastest-growing flat panel displays due to its lightness and thinness. However, compared with cathode ray tube displays, the viewing angle of thin film transistor liquid crystal display (Thin Film Transistor, TFT-LCD) is relatively narrow, which brings great limitations to its application in high-end fields that require strict viewing angles. Such as aerospace, medical and other fields. With the rapid development of wide viewing angle technology in the LCD field, the viewing angles of many products can reach horizontal viewing angles and vertical viewing angles of 85°/85°, or even larger viewing angles.

LCD wide viewing angle technology currently mainly includes vertical alignment (Vertical Alignment, VA) technology and in-plane switching (In Plane Switching, IPS) technology. The VA technology is realized by forming a structure (Protrusion, protrusion) on the pixel electrode. The advantage of the vertical orientation mode is that the front contrast ratio is extremely high, usually reaching 600:1 and above. In addition, no friction treatment is required in the process. The VA mode LCD works in the normally black mode, which will also greatly reduce the possibility of "bright spots" appearing on the LCD panel.

In a multi-domain vertical alignment (MVA) liquid crystal display device, small protrusions are formed on the upper and lower substrates, the liquid crystal molecules are vertically aligned, and the directions of the polarizer and the analyzer are perpendicular to each other, so no power is applied time is dark. When a voltage is applied, the liquid crystal molecules align toward the horizontal direction along the pretilt angle direction generated by the protrusions, and deviate from the vertical alignment, thereby realizing display. However, the existence of tiny bumps complicates the LCD manufacturing process and reduces the yield rate of the product.

With the rapid development of personal mobile devices, in addition to the wide viewing angle requirements for LCD, people also need to realize the controllability of the viewing angle in different applications, such as the narrow viewing angle of the mobile phone screen when displaying personal communication, playing digital display, etc. Wide viewing angles can be achieved when programs or multiple people watch at the same time. This technology will bring great convenience to people's production and life.

In addition to a liquid crystal cell operating in TN mode or other modes, a traditional viewing angle controllable system needs to attach at least one liquid crystal cell to control the viewing angle on the liquid crystal cell, so the thickness of the viewing angle control liquid crystal system is relatively large. There is another method to control the viewing angle by simultaneously adopting two liquid crystal working modes in the liquid crystal cell, such as VA mode and fringe field switching (FFS, Fringe field switching) mode, ECB mode and FFS mode.

FIG. 1 is a schematic structural view of a viewing angle controllable liquid crystal display device in the prior art, in which liquid crystal molecules rotate under the joint action of a horizontal electric field and a vertical electric field, and its basic structure is similar to that of an IPS or FFS mode LCD. The liquid crystal display device shown in Fig. 1 comprises, the first electrode 003 and the second electrode 004 that are arranged on the TFT array substrate 005, the third electrode 001 that is arranged on the color filter film substrate 008 (color filter, CF), in order to An organic film 002 and an alignment film 006 that reduce the influence of the vertical electric field. Among them, when the first electrode 003 and the second electrode 004 on the array substrate 005 are powered on, the liquid crystal molecules rotate along the plane parallel to the upper and lower substrates under the action of the horizontal electric field to form a wide viewing angle; when the third electrode on the CF substrate 008 When 001 and the first electrode 003 and the second electrode 004 on the array substrate 005 are powered on at the same time, the horizontal electric field will be modulated by the vertical electric field to cause the liquid crystal molecules to rotate in a direction perpendicular to the upper and lower substrates, thereby forming a narrow viewing angle mode.

The above technical solution is disclosed in the patent application with the patent application number 200610169935.8. However, in this technical solution, it is necessary to rub the alignment layer 006 on the inner side of the upper and lower substrates, usually forming a rubbing direction at an angle of 15° with the horizontal strip electrode However, various problems such as edge mura (a kind of poor picture) will occur in the rubbing alignment process, which greatly reduces the product yield, thereby reducing production efficiency.

In order to solve the above problems, the present invention provides a liquid crystal display device with controllable viewing angle, which can effectively simplify the manufacturing process of the liquid crystal display device, realize wide and narrow viewing angle control, and provide high image display quality.

Contents of the invention

The object of the present invention is to provide a liquid crystal display device that can realize switching control between a wide viewing angle mode and a narrow viewing angle mode.

The purpose of the present invention is also to provide a driving method of a liquid crystal display device, which can control the wide viewing angle working mode and the narrow viewing angle working mode of the liquid crystal display device.

In order to solve the above-mentioned technical problems, the liquid crystal display device of the present invention includes a first substrate and a second substrate oppositely arranged, signal lines and scanning lines arranged vertically to each other formed on the first substrate, the signal lines and the a plurality of pixel regions formed by the crossing of the scanning lines, and an area sandwiched between the first substrate and the second substrate and perpendicular to the surface of the first substrate or the second substrate in an unpowered state A liquid crystal layer arranged on the surface, wherein a pixel electrode is formed on the first substrate, a first common electrode is formed on the second substrate to form a monodomain arrangement of the liquid crystal layer, and a liquid crystal layer is formed on the second substrate A second common electrode is formed on the liquid crystal layer to form a multi-domain arrangement of the liquid crystal layer.

As a preferred solution of the present invention, the pixel electrode, the first common electrode and the second common electrode are ITO, IZO or IGO electrodes.

As another preferred solution of the present invention, by setting slits on the pixel electrode, the first common electrode and the second common electrode, the monodomain arrangement of the liquid crystal layer or the Multi-domain arrangement.

In order to solve the above-mentioned technical problems, the driving method of the liquid crystal display device of the present invention includes the following steps: applying a voltage to the pixel electrode arranged on the first substrate and the first common electrode arranged on the second substrate to form the first alignment of the liquid crystal layer Arranging; applying a voltage to the pixel electrode disposed on the first substrate and the second common electrode disposed on the second substrate to form a second alignment arrangement of the liquid crystal layer; wherein applying a voltage to the first substrate by selection A common electrode or the second common electrode is used to switch between the narrow viewing angle mode and the wide viewing angle mode.

As a preferred solution of the present invention, the first alignment is a single-domain alignment of the liquid crystal layer, and the second alignment is a multi-domain alignment of the liquid crystal layer.

The liquid crystal display device and its driving method of the present invention can easily realize the switching between the wide viewing angle mode and the narrow viewing angle mode, and since there is no need to rub the alignment layer, the process flow can be simplified, the cost can be reduced, and the banding caused by friction can also be avoided. There are many problems such as poor display effect of the incoming screen.

Description of drawings

FIG. 1 is a schematic structural view of a viewing angle controllable liquid crystal display device in the prior art.

FIG. 2 is a cross-sectional view of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 3 is a schematic diagram of the pixel structure of the narrow viewing angle mode of the liquid crystal display device according to the first embodiment of the present invention.

FIG. 4 is a schematic diagram of a pixel structure in a wide viewing angle mode of the liquid crystal display device according to the first embodiment of the present invention.

FIG. 5 is a schematic diagram of a pixel structure of a liquid crystal display device according to a first embodiment of the present invention.

6 is a software simulation diagram of directors of liquid crystal molecules in the wide viewing angle mode of the liquid crystal display device according to the first embodiment of the present invention.

7 is a software simulation diagram of the transmittance of the pixel structure of the liquid crystal display device in the wide viewing angle mode according to the first embodiment of the present invention.

8 is a simulated view of the viewing angle obtained by adding a compensation film outside the liquid crystal cell in the wide viewing angle mode of the liquid crystal display device according to the first embodiment of the present invention.

FIG. 9 is a schematic diagram showing a modified example of the pixel structure of the liquid crystal display device in the first embodiment of the present invention.

FIG. 10 is a schematic diagram of a pixel structure of a liquid crystal display device according to a second embodiment of the present invention.

Detailed ways

The viewing angle controllable liquid crystal display device and its driving method of the present invention will be described below with reference to the accompanying drawings.

first embodiment

FIG. 2 is a schematic structural view of a liquid crystal display device according to the first embodiment of the present invention. As shown in FIG. 2 , the liquid crystal display device according to the first embodiment of the present invention includes a first substrate 107 and a second substrate 100 arranged opposite to each other. , the pixel electrode 105 disposed on the first substrate 107, the first common electrode 103 and the second common electrode 101 disposed on the second substrate 100, the organic insulation disposed between the first common electrode 103 and the second common electrode 101 layer 102, the liquid crystal molecules 104 sandwiched between the first substrate 107 and the second substrate 100 and arranged vertically to the upper and lower substrates when no power is applied, and polarizers 106 respectively arranged outside the first substrate 107 and the second substrate 100 And a polarizer 108, and an alignment layer (not shown). The present invention realizes the control of the wide and narrow viewing angles of the liquid crystal display device by selectively applying a voltage to the first common electrode 103 or the second common electrode 101 .

The pixel structures of the wide viewing angle mode and the narrow viewing angle mode will be described respectively below with reference to FIGS. 3-5 . FIG. 3 is a schematic diagram of the pixel structure of the narrow viewing angle mode of the liquid crystal display device according to the first embodiment of the present invention. As shown in FIG. 3, the first common electrode 103 is shown by a dotted line, the pixel electrode 105 is shown by a thin black solid line, 110 is a scanning line arranged on the first substrate 106, 111 is arranged on the first substrate 106, The signal line perpendicular to the scanning line 110, 112 is the a-Si layer in the thin film transistor (TFT) structure, 113 is the via hole connecting the pixel electrode 105 with the TFT source/drain metal 115, and 114 is the lower pole of the storage capacitor plate. Along the direction of the scanning line 110, the first common electrode 103 is translated relative to the pixel electrode 105, so that when viewed from the upper substrate 100, there are gaps 109(a) and 109(a) between the pixel electrode 105 and the first common electrode 103. b). In the direction along the scan line 110, gaps 109(a) and 109(b) are formed by forming slits on different sides of the first common electrode 103 and the pixel electrode 105, respectively, wherein the gap 109(a) and 109(b) have a width of 4 μm-12 μm.

FIG. 4 is a schematic diagram of a pixel structure in a wide viewing angle mode of the liquid crystal display device according to the first embodiment of the present invention. As shown in FIG. 4 , the second common electrode 101 is shown by a thick black solid line, and the pixel electrode 105 is shown by a thin black solid line. The other components are the same as those in Fig. 3 and will not be repeated here. By forming slits on the second common electrode 101, the second common electrode 101 is formed into two connected rectangular sub-common electrodes, and the two sub-common electrodes are translated in opposite directions to form a pixel structure as shown in FIG. 4 , so that When looking down from the upper substrate 100 , there is a gap between the pixel electrode 105 and the second common electrode 101 at the edge of the pixel, and the width of the gap is 4 μm-12 μm.

FIG. 5 is a schematic diagram of a pixel structure of a liquid crystal display device according to a first embodiment of the present invention. As shown in FIG. 5, the first common electrode 103 is shown by a dotted line, the second common electrode 101 is shown by a thick black solid line, and the pixel electrode 105 is shown by a thin black solid line, wherein the electrode pattern and relative position of each electrode are the same as those shown in FIG. What is shown in FIG. 3 and FIG. 4 are the same, so no more details are given here.

The working principle of the liquid crystal display device according to the first embodiment of the present invention will be described in detail below with reference to FIGS. 3-5 . In the narrow viewing angle working mode, a voltage is applied to the pixel electrode 105 and the first common electrode 103, and the second common electrode 101 is floating (floating). In this case, the edge of the pixel electrode 105 and the first common electrode 103 Slits are formed to form an inclined electric field at the edges of the two electrodes, and the liquid crystal molecules 104 change from vertical arrangement to parallel arrangement to the upper substrate 100 under the action of the electric field, thereby forming a single domain direction and realizing narrow viewing angle display. At this time, the viewing angle of the liquid crystal display device is about ±20°.

In the wide viewing angle working mode, power is applied to the pixel electrode 105 and the second common electrode 101 at the same time, and the first common electrode 103 is floated (floating), so that the slit formed on the second common electrode 101 and the pixel The electrodes 105 are combined so that the liquid crystal molecules 104 change from a vertical arrangement to an arrangement of four domains in an electrified state, thereby realizing a wide viewing angle mode.

6 is a software simulation diagram of the directors of liquid crystal molecules in the wide viewing angle mode of the liquid crystal display device of the first embodiment of the present invention. It can be seen from the figure that the liquid crystal display device of the first embodiment operates in the wide viewing angle mode. The molecules have a distinct four-domain distribution.

7 is a software simulation diagram of the transmittance of the pixel structure of the liquid crystal display device in the wide viewing angle mode according to the first embodiment of the present invention. 8 is a simulation view of the viewing angle obtained by adding a compensation film outside the liquid crystal cell in the wide viewing angle mode of the liquid crystal display device according to the first embodiment of the present invention, wherein the compensation film is a C-plate compensation film for compensating liquid crystal molecules. It can be seen from Figure 8 that when the liquid crystal display device works in the wide viewing angle mode, the viewing angles of the liquid crystal display device in the oblique 45° and 135° directions can reach more than 80°, which can meet the requirements of playing digital images and multiple people watching at the same time requirements. If a 1/4 biaxial compensation film is used at the position of the upper and lower polarizers, the viewing angle of the device will be further increased.

The slit shape of the second common electrode 101 used in the wide viewing angle mode of the liquid crystal display device may include a rectangle, an epaulet shape, and the like.

In the first embodiment of the present invention, the normally black VA display mode is adopted, and the liquid crystal material can be negative liquid crystal. The polarizer 107 and the polarizer 108 can be any combination of ordinary linear polarizer, 1/4 wave plate, 1/2 wave plate, uniaxial compensation film, biaxial compensation film and any viewing angle compensation device. And this embodiment is not limited to the first common electrode 103 forming a single-domain electrode pattern, while the second common electrode 101 forms a four-domain electrode pattern, or the second common electrode 101 forms a single-domain electrode pattern, while the first electrode 103 forms a four-domain electrode pattern.

It can be seen from Figure 7 that due to the influence of the fringe electric field, some domain lines (black parts in the pixel display area) will inevitably appear in the pixel, so that the domain line part will reduce the transmittance of the display area to a certain extent . In view of this situation, a modified example of the pixel structure of the liquid crystal display device as shown in FIG. 9 is proposed.

FIG. 9 shows a modified example of the pixel structure of the liquid crystal display device in the first embodiment of the present invention, and the figure shows a schematic diagram of the pixel structure of the liquid crystal display device in a wide viewing angle mode. The shapes and positions of the first common electrode and the second common electrode are the same as those shown in FIG. 4 and FIG. 5 , and the difference from the pixel structure in FIG. 4 lies in the position and shape of the lower plate of the storage capacitor. Form the shape and position of the storage capacitor lower plate 114' as shown in Figure 9, wherein the storage capacitor lower plate 114' is formed at the position of the domain line in the middle part of the pixel shown in Figure 7, so that the storage capacitor can be The metal electrode of the lower plate is placed at the position of the domain line of the pixel, thereby greatly increasing the aperture ratio of the pixel.

second embodiment

FIG. 10 is a schematic diagram of a pixel structure of a viewing-angle-controllable liquid crystal display device according to a second embodiment of the present invention, wherein FIG. 10(a) and FIG. 10(b) are schematic diagrams of pixel structures in a narrow viewing angle mode and a wide viewing angle mode, respectively. As shown in Figure 10 (a), the first common electrode 203 is shown with a thick black solid line, and the pixel electrode 205 is shown with a thin black solid line, and in the direction along the scanning line 204, the first common electrode 203 is opposite to the pixel The electrode 205 is translated to form a gap, the translation is formed by setting a slit on the first common electrode 203 and the pixel electrode 205, and the width of the gap is 4 μm-12 μm. As shown in Figure 10(b), the second common electrode 201 is shown by a thick black solid line, and the pixel electrode 205 is shown by a thin black solid line, and the second common electrode 201 is formed by forming a slit (slit). Formed as two connected rectangular sub-common electrodes, and viewed from the upper substrate, a gap is formed between the second common electrode 201 and the pixel electrode 205 at the edge of the pixel, and the width of the gap is 4 μm-12 μm.

The working principle of the viewing angle controllable liquid crystal display device according to the second embodiment of the present invention will be described in detail below. As shown in FIG. 10(a), in the working mode of narrow viewing angle, a voltage is applied to the first common electrode 203 and the pixel electrode 205, and the second common electrode 201 is floating (floating). At this time, due to the first common electrode There is a gap between the gate line 203 and the pixel electrode 205 along the direction of the gate line 204, so an oblique electric field is formed between the upper substrate and the lower substrate, so that all liquid crystal molecules rotate from being vertical to the upper and lower substrates to approximately parallel to the upper and lower substrates. The substrates are aligned and form monodomains to obtain a working mode with a narrow viewing angle. In the narrow viewing angle working mode, the viewing angle of the liquid crystal display device is about ±20°.

As shown in Figure 10(b), in the working mode of wide viewing angle, a voltage is applied to the second common electrode 201 and the pixel electrode 205, and the first common electrode 203 is floating (floating), because the pixel electrode 205 and the second The common electrode 201 is formed into a shape as shown in the figure through slits at the edge of the pixel, so a symmetrical oblique electric field will be formed between the upper substrate and the lower substrate, and the liquid crystal molecules will form a pattern of pouring from the edge of the pixel to the center of the sub-common electrode. At this time, the liquid crystal molecules form multiple domains. Compared with the case where the liquid crystal display device of the first embodiment of the present invention forms four domains in the wide viewing angle mode, the viewing angle is further expanded.

The structure and driving method of the viewing angle controllable liquid crystal display device according to the second embodiment of the present invention have been described above. It should be pointed out that the pattern of the second common electrode 201 is not limited to the above description, and it can be formed to be common to the pixel electrode 205. Various electrode patterns with multi-domain or even infinite multi-domain can be produced. Moreover, this embodiment is not limited to the first common electrode 203 forming a single domain, and the second common electrode 201 forming a multi-domain electrode pattern, or the first common electrode may form a multi-domain electrode pattern, while the second common electrode forms a single domain electrode pattern.

The present invention applies Vertical Alignment (VA) technology to realize a liquid crystal display device with controllable viewing angle, by respectively setting different electrode structures of the pixel electrode on the lower substrate, the first common electrode and the second common electrode on the upper substrate, and using pixel The driving method of the electrode working with the first common electrode and the second common electrode floating, and the driving method of the pixel electrode working with the second common electrode and the first common electrode floating realize the control of the viewing angle from narrow to wide in VA mode. In the present invention, the viewing angle can be changed from narrow to wide or from wide to narrow by simply selecting the driving method of the common electrode in the working state. Compared with the traditional viewing angle controllable LCD, the present invention does not need to rub the alignment layer, so it has the advantages of simple structure and simple manufacturing process, and can avoid poor display effect caused by friction, thereby improving the picture display quality of the liquid crystal display device , and reduce costs, improve production efficiency, and enhance process feasibility.

Those skilled in the art will appreciate that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, if any modifications and variations fall within the scope of protection of the appended claims and their equivalents, the present invention is deemed to cover such modifications and variations.

Claims (10)

1. liquid crystal indicator comprises:

First substrate that is oppositely arranged and second substrate,

Be formed at signal wire that is vertically aligned with each other and sweep trace on described first substrate,

The a plurality of pixel regions that intersect to form by described signal wire and described sweep trace, and

The liquid crystal layer that is sandwiched between described first substrate and described second substrate, under powering state not, arranges perpendicular to the surface of the surface of described first substrate or described second substrate, wherein

On described first substrate, form pixel electrode,

On described second substrate, form first public electrode and second public electrode, and be arranged at the insulation course between first public electrode and second public electrode,

The pixel electrode and first public electrode are applied voltage, and second public electrode is floated, arrange in order to the single domain that forms described liquid crystal layer; The pixel electrode and second public electrode are applied voltage, and first public electrode is floated, arrange in order to the multidomain that forms described liquid crystal layer.

2. liquid crystal indicator according to claim 1, wherein said pixel electrode, described first public electrode and described second public electrode are ITO, IZO or IGO electrode.

3. liquid crystal indicator according to claim 1 is wherein carved seam by being provided with on described pixel electrode, described first public electrode and described second public electrode, arrange or the multidomain of described liquid crystal layer is arranged with the single domain that forms described liquid crystal layer.

4. liquid crystal indicator according to claim 1 wherein switches narrow field-of-view mode and wide field-of-view mode by the voltage that adjusting puts on described first public electrode and described second public electrode.

5. liquid crystal indicator according to claim 3, wherein said first public electrode are along the direction of described sweep trace, with respect to described pixel electrode skew.

6. liquid crystal indicator according to claim 3, wherein said second public electrode form two sub-public electrodes that are connected with each other, and each limit of the close described pixel edges of described two sub-public electrodes is offset with respect to described pixel electrode.

7. according to claim 5 or the described liquid crystal indicator of claim 6, the distance of wherein said skew is 4 μ m-12 μ m.

8. liquid crystal indicator according to claim 6 wherein is provided with the bottom crown of memory capacitance on described first substrate, and the position of the farmland line of arranging corresponding to described multidomain and the bottom crown that shape is provided with described memory capacitance.

9. liquid crystal indicator according to claim 1, the first viewing angle compensation device and the second viewing angle compensation device wherein are set respectively on described first substrate and described second substrate, and the combination in any of the described first viewing angle compensation device and the described second viewing angle compensation device compensate film that can make for line polaroid, quarter wave plate, 1/2 wave plate, uniaxial compensation film, biaxial compensation film and by coating process.

10. the driving method of a liquid crystal indicator may further comprise the steps,

Apply voltage for pixel electrode that is arranged at first substrate and first public electrode that is arranged at second substrate, and second public electrode is floated, arrange with the single domain that forms liquid crystal layer;

Apply voltage for described pixel electrode that is arranged at described first substrate and second public electrode that is arranged at described second substrate, and first public electrode is floated, arrange with the multidomain that forms liquid crystal layer;

Wherein by selecting to apply a voltage to described first public electrode and described second public electrode switches narrow field-of-view mode and wide field-of-view mode.

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