KR20070030867A - Liquid crystal display and liquid crystal material - Google Patents

Abstract

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display substrate and a liquid crystal display device using the same, in which a light transmittance is improved without a decrease in response speed to tone changes. A drain bus line formed on an array substrate which is coupled to an opposing substrate provided in a facing relationship to switch liquid crystals, a TFT connected to the drain bus line, and connected to the TFT along a space and provided in parallel with the drain bus line A pixel electrode having a stripe-shaped electrode is provided, and the stripe-shaped electrode in the vicinity of the drain bus line has an electrode width formed narrower than the width of the internal electrode positioned therein.

Substrate for liquid crystal display, liquid crystal display, drain bus line, TFT, space, pixel electrode

Description

Liquid crystal display and liquid crystal material {LIQUID CRYSTAL DISPLAY AND LIQUID CRYSTAL MATERIAL}

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a first explanatory diagram for explaining the principle of determining the structure of a pixel electrode 3 in a first mode for carrying out the invention.

Fig. 2 is a second explanatory diagram for explaining the principle of determining the structure of the pixel electrode 3 in the first mode for carrying out the invention.

3 is a third explanatory diagram showing a principle of determining the structure of the pixel electrode 3 in the first mode for carrying out the invention.

4 is a fourth explanatory diagram showing a principle of determining the structure of the pixel electrode 3 in the first mode for carrying out the invention.

Fig. 5 shows an array substrate viewed from the normal direction of the substrate surface such that the pixel 2 of the MVA-LCD according to Example 1-1 in the first mode for carrying out the invention appears.

6 shows a cross-sectional structure of the LCD taken along line A-A of FIG.

Fig. 7 shows a variation of the MVA-LCD of Example 1-1 in the first mode for carrying out the invention.

Fig. 8 shows an array substrate viewed from the normal direction of the substrate surface such that the pixels 2 of the MVA-LCDs according to Examples 1-2 in the first mode for carrying out the invention are shown.

Fig. 9 shows an array substrate viewed from the normal direction of the substrate surface such that the pixels 2 of the MVA-LCDs according to Examples 1-3 in the first mode for carrying out the invention are shown.

Fig. 10 shows the array substrate seen from the normal direction of the substrate surface such that the pixel 2 of the MVA-LCD according to Example 1-4 in the first mode for carrying out the invention appears.

FIG. 11 is a cross-sectional view of the LCD taken along the line B-B in FIG. 10; FIG.

12 is a cross-sectional view of the LCD taken along the line C-C of FIG.

Figure 13 shows a variant of the MVA-LCD of Examples 1-4 in a first mode for carrying out the invention.

14 (a) and 14 (b) show an MVA-LCD having two separate alignment regions, and FIG. 14 (a) shows pixels of the MVA-LCD viewed from the normal direction of the substrate surface. 2), and FIG. 14B is a diagram showing a cross section of the MVA-LCD shown in FIG. 14A taken in parallel with the drain bus line 6;

15 is an enlarged view of pixels of the MVA-LCD in the normal direction of the substrate surface;

16 shows a pixel 2 of a previously proposed MVA-LCD viewed in the normal direction of the substrate surface.

FIG. 17 is a cross sectional view taken along the line D-D in FIG. 16; FIG.

18 is an enlarged view of pixels of a conventional MVA-LCD seen in the normal direction of the substrate surface.

19 (a) and 19 (b) show a pixel 2 of an MVA-LCD having two separate alignment regions according to Example 2-1 in a second mode for carrying out the invention. .

20 (a) and 20 (b) show the pixel 2 of the MVA-LCD having two separate alignment regions according to Example 2-2 in the second mode for practicing the present invention. drawing.

Fig. 21 is a cross sectional view of the liquid crystal display device in the third mode for carrying out the invention taken in the direction perpendicular to the substrate;

Fig. 22 is a cross sectional view showing an array substrate side of a cross section of a liquid crystal display device in a third mode for carrying out the invention taken in a direction perpendicular to the substrate surface;

Fig. 23 is another sectional view showing the array substrate side of the cross section of the liquid crystal display device in the third mode for carrying out the invention taken in the direction perpendicular to the substrate surface;

Fig. 24 is another cross-sectional view showing the array substrate side of the cross section of the liquid crystal display device in the third mode for carrying out the invention taken in the direction perpendicular to the substrate surface.

Fig. 25 is another cross sectional view showing the array substrate side of the cross section of the liquid crystal display device in the third mode for carrying out the invention taken in the direction perpendicular to the substrate surface;

Fig. 26 is another cross sectional view showing the array substrate side of the cross section of the liquid crystal display device in the third mode for carrying out the invention taken in the direction perpendicular to the substrate surface;

27 (a) and 27 (b) show a previously proposed orientation control structure.

28 shows a previously proposed orientation control structure.

Fig. 29 is a view showing a fish bone pattern in which a stripe-shaped electrode 8 and a space 10 are combined in a plurality of directions viewed from the normal direction of the substrate surface.

30 shows a section taken along line E-E of FIG. 29;

31 (a) to 31 (d) show stripe shapes so as to indicate an orientation state between the electrode width L of the stripe-shaped electrode 8 and the width S of the space 10 during halftone display. The figure which shows the result of the Example performed at the boundary between the electrode 8 and the space 10 (spine part of a fish bone pattern).

Fig. 32 is a diagram showing a relationship between the electrode width L of the stripe-shaped electrode 8 of the LCD in the fourth mode for carrying out the invention and the width S of the space 10 thereof.

Fig. 33 shows Example 4-1 in the fourth mode for carrying out the invention.

Fig. 34 shows Embodiment 4-2 in the fourth mode for carrying out the invention.

35 is a view showing the configuration of a display electrode and a common electrode of a conventional IPS-LCD.

Fig. 36 is a diagram showing the configuration of a liquid crystal display device according to Example 6-1 in the sixth mode for carrying out the invention.

Fig. 37 is a sectional view showing the configuration of a liquid crystal display device according to Example 6-2 in the sixth mode for carrying out the invention;

Fig. 38 is a sectional view showing the configuration of a liquid crystal display device according to Example 6-3 in the sixth mode for carrying out the invention;

Fig. 39 shows the structure of a liquid crystal display according to Example 6-3 in the sixth mode for carrying out the invention.

Fig. 40 is a sectional view showing the configuration of a liquid crystal display device according to Example 6-4 in the sixth mode for carrying out the invention;

Fig. 41 is a diagram showing the configuration of a liquid crystal display device according to Example 6-4 in the sixth mode for carrying out the invention.

Fig. 42 is a sectional view showing the configuration of a liquid crystal display device according to Example 6-5 in the sixth mode for carrying out the invention;

43 schematically shows the structure of a copolymer.

44 (a) and 44 (b) are diagrams showing the principle of a liquid crystal display device in a seventh mode for carrying out the invention.

45 (a) and 45 (b) show the principle of a liquid crystal display device in a seventh mode for carrying out the invention.

46A and 46B show the structure of a liquid crystal display device according to Example 7-1 in a seventh mode for carrying out the invention.

47A and 47B show the structure of a liquid crystal display device according to Example 7-2 in the seventh mode for carrying out the invention.

* Description of the symbols for the main parts of the drawings *

3: pixel electrode

8: stripe shape electrode

10: space

20, 30: glass substrate

24: liquid crystal layer

26: common electrode

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate for a liquid crystal display device and a liquid crystal display device using the same. In particular, a horizontal electric field is applied to a vertically aligned (VA) mode in which a liquid crystal having negative dielectric anisotropy is vertically aligned, and a horizontal alignment liquid crystal device having positive dielectric anisotropy. The present invention relates to a substrate for a liquid crystal display device in an applied in-plane switching (IPS) mode and the like, and also to a liquid crystal display device using the same.

According to the present invention, a liquid crystal layer comprising photopolymerized or thermally polymerized polymer components (monomers and oligomers) is sealed between substrates, and the voltage applied to the liquid crystal layer is adjusted (where the voltage applied thereto may be 0, and this operation will be described below The present invention relates to a liquid crystal display device in which the orientation of liquid crystal is fixed by polymerizing a polymer component, and the present invention also relates to a substrate used in such a liquid crystal display device. .

Multi-domain vertical alignment mode liquid crystal display device (hereinafter simply referred to as "MVA-LCD") in which liquid crystals having negative dielectric anisotropy are vertically aligned, and banks (linear protrusions) on a substrate or cutout (slit) at the electrode are provided as an alignment adjusting structure. Is known. Since the alignment adjustment structure is provided, the liquid crystal can be controlled to be aligned in a plurality of alignment directions when a voltage is applied without having to perform a rubbing step on the alignment film at all. Such MVA LCDs have better viewing angle characteristics than conventional twisted nematic (TN) mode LCDs.

However, the conventional MVA LCD has a problem that dark appears when displaying white because of low luminance. This is fundamentally due to the fact that the darkness appears due to the decrease in transmittance when white is displayed because dark lines appear on the slits or protrusions serving as boundaries of the orientation separation. Although this problem can be alleviated by keeping the gap between the projections or slits sufficiently large, as a result, the number of projections or slits, which are alignment adjustment structures, is reduced, so that the alignment of the liquid crystal after applying a predetermined voltage to the liquid crystal The time required to fix the circuit becomes longer, and as a result, the response speed decreases.

In order to alleviate this problem and provide an MVA-LCD having high brightness and a high response speed, it has been proposed to use a polymer fixing method. According to the polymer fixing method, a liquid crystal composition obtained by mixing polymer components such as monomers and oligomers (hereinafter, simply referred to as “monomers”) into a liquid crystal is sealed between the substrates. This monomer is polymerized with the liquid crystal molecules and tilted by a voltage applied between the substrates. As a result, a liquid crystal layer tilted at a predetermined tilt angle is obtained even after the application of the voltage is stopped, which makes it possible to fix the alignment of the liquid crystal. The monomer selects a material which is polymerized by heat or light (ultraviolet light).

However, the polymer fixing method has some problems associated with irregularities in the display when the image is displayed on the LCD and completed. The first problem is that when the liquid crystal is driven to polymerize the monomer, irregularity occurs in the display of the image on the completed LCD due to the abnormal orientation of the liquid crystal locally generated.

IPS mode liquid crystal display devices (hereinafter simply referred to as "IPS-LCDs") in which a horizontal field is applied to horizontally oriented liquid crystals having positive dielectric anisotropy have desirable viewing angle characteristics as MVA-LCDs. However, since the liquid crystal molecules are switched on the comb-shaped electrode and the horizontal plane in the IPS-LCD, a backlight unit having a large light intensity is required because the aperture ratio of the pixel to the comb-shaped electrode is greatly reduced.

Although the actual aperture ratio of the pixel to protrusions or slits is not significantly reduced compared to IPS-LCD for comb-shaped electrodes, the panel of MVA-LCD has lower light transmittance than TN mode LCD. For this reason, neither MVA-LCD nor IPS-LCD has been used in recent years in notebook personal computers that need to lower power consumption.

In the present MVA-LCD, in order to tilt the liquid crystal molecules in four directions when applying a voltage to achieve a wide viewing angle, a plurality of linear protrusions or slits having a linear cutout in a part of the pixel electrode are complicated configuration. To the pixels. This lowers the light transmittance of the pixel.

In order to alleviate this problem, the orientation adjustment operation in the case where the gap between the adjacent linear protrusions having a simple structure is kept large will be described below. 14 (a) and 14 (b) show an MVA-LCD having two separately oriented regions. Fig. 14A shows the pixel 2 of the MVA-LCD seen in the vertical direction of the substrate surface. FIG. 14B is a diagram showing a cross section of the MVA-LCD shown in FIG. 14A taken in parallel with the drain bus line 6. FIG. 14A shows three pixels 2 corrected by one gate bus line 4. As shown in FIGS. 14A and 14B, two linear protrusions 68 extending in parallel with the gate bus line 4 are positioned on one side of the gate bus line 4. It is formed in the vicinity of both ends of (3). A linear projection 66 extending in parallel with the gate bus line 4 is formed in the common electrode region on the opposing substrate, which region includes the central region of the pixel. As for the array substrate, an insulating film (gate insulating film) 23 is formed on the glass substrate 20 and the gate bus line 4, and the insulating film 22 is formed thereon.

In this configuration, when a voltage is applied between the pixel electrode 3 and the common electrode 26 to change the distribution of the electric field in the liquid crystal layer 24, the liquid crystal molecules 24a having negative dielectric anisotropy move in two directions. Is tilted. In particular, the liquid crystal molecules 24a are tilted in the direction from the linear projections 68 on both sides of the pixel 2 on one side of the gate bus line 4 to the linear projections 66 on the opposing substrate. As a result, a multi-domain divided into two parts, that is, an upper part and a lower part is formed. In the MVA mode, the tilt direction of the liquid crystal molecules 24a is generated by the linear protrusions (or slits) starting from molecules located in the vicinity of the linear protrusions 66 and 68 (or in the vicinity of the slits). Almost determined by Therefore, when the gap between the linear protrusions (or slits) is very large as shown in Figs. 14A and 14B, the response of the liquid crystal molecules to the application of voltage is very slow. This is because the transfer of the tilt of the liquid crystal molecules 24a takes time.

A possible solution to this is to use a polymer fixing method that employs a liquid crystal layer 24 containing monomers that can be polymerized instead of conventional liquid crystal materials. According to this polymer fixing method, the monomer is polymerized at a voltage applied to the liquid crystal layer 24, and the resulting polymer stores the tilt direction of the liquid crystal molecules 24a.

However, in the structures shown in FIGS. 14A and 14B, when a voltage is applied to the liquid crystal layer 24, the liquid crystal molecules 24a near the drain bus line 6 are connected to the drain bus line. The electric field generated at the edge of the pixel electrode 3 in the vicinity of 6) is tilted in a direction 90 degrees different from the intended tilt direction. As a result, even when the polymer fixing method is applied, the large dark portion X1 extending along the drain bus line 6 to the outside of the black matrix BM can be seen by enlarging the MVA-LCD in the vertical direction of the substrate surface. As shown in Fig. 15, each of the display pixels 2 will be recognized.

To solve this problem, in a previous application filed by the present applicant (Japanese Patent Application No. 2001-264117 filed on August 31, 2001), a pixel electrode on an array substrate having a TFT 16 formed thereon ( 3) is proposed to be an electrode having a stripe shape in a line-and-space pattern. By way of example, Fig. 16 shows the embodiment where the pixel 2 of the MVA-LCD is viewed in the vertical direction of the substrate surface. As shown in FIG. 16, the pixel electrode 3 has a stripe-shaped electrode 8 and a space 10 formed in a line and space pattern in parallel with the drain bus line 6.

Typically, the alignment adjusting force provided by the alignment film acts only on the liquid crystal molecules 24a in contact with the alignment film and not on the liquid crystal molecules in the center of the device in the direction of the cell gap. Therefore, the alignment direction of the liquid crystal molecules 24a at the center of the device in the direction of the cell gap is greatly influenced and deformed by the electric field generated at the edge of the pixel. In the case of the pixel electrode having the stripe-shaped electrode 8 and the space 10 in parallel with the drain bus line 6, the liquid crystal molecules 24a are the stripe-shaped electrode 8 and the space 10 when a voltage is applied. Tilt parallel to In addition, since the tilt direction of all the liquid crystal molecules 24a is determined by the stripe-shaped electrode 8 and the space 10, the influence of the transverse electric field generated at the edge of the pillar can be minimized.

Hereinafter, the liquid crystal display device proposed in the above-described application and a manufacturing method thereof will be described. FIG. 16 shows the pixel 2 of the MVA-LCD according to the present proposal in the vertical direction of the substrate surface, and FIG. 17 shows the cross-sectional configuration taken along the line D-D of FIG. As shown in FIG. 16, the pixel electrode 3 has the stripe-shaped electrode 8 and the space 10 in a line and space pattern in parallel with the drain bus line 6. As shown in FIG. The stripe-shaped electrode 8 is electrically connected by a connection electrode 64 formed in the center of the pixel 2 substantially in parallel with the gate bus line 4. A part of the stripe-shaped electrode 8 is connected to the source electrode 62 provided in a relationship facing the drain electrode 60 of the TFT 16.

As shown in Fig. 17, a linear projection 66 extending in parallel with the gate bus line 4 is formed on an opposing substrate at a relation position facing each other with the connecting electrode 64 at the center of the pixel region. The alignment direction of the liquid crystal molecules 24a may be more strongly determined by the linear protrusions 66.

Obviously, instead of providing the linear protrusions 66 on the opposing substrate, a rubbing process may be performed on the array substrate or the alignment film on the opposing substrate. In this case, the two regions B and C of the array substrate shown in FIG. 16 are rubbed toward the connecting electrode 64 as indicated by the arrows in FIG. The opposing substrate is rubbed in the direction away from the connecting electrode 64. Optical methods of orientation may optionally be used.

The panel structure shown in FIGS. 16 and 17 is a liquid crystal layer 24 with light along with liquid crystal molecules 24a in the pixel 2 tilted in a predetermined direction by applying a voltage to the liquid crystal layer 24 to which the photopolymerization monomer is added. ) Is a structure to examine. As a result, the monomer is polymerized to fix the pretilt angle and / or orientation of the liquid crystal molecules 24a. By driving the completed MVA-LCD for display and observing the display area, it was found that in the related art, since there is no dark portion X1, light is transmitted through the entire pixel area, thereby improving the transmittance.

However, in the structure proposed in the above-mentioned application, the liquid crystal molecules positioned on the space 10 are not oriented (tilt) because they are not sandwiched by electrodes from the top and the bottom even if the alignment of the liquid crystal layer is fixed. This is because the electric field is not applied directly. As a result, a problem arises in that the transmittance is reduced around the space 10. Therefore, the structure shown in FIG. 16 has better fixation of the alignment of the liquid crystal as compared with the structure shown in FIGS. 14A and 14B, and prevents the occurrence of the dark portion X1 as shown in FIG. 15. Even if the transmittance in the peripheral region of the pixel is improved, the overall transmittance of the pixel does not improve because the optical transmittance of the pixel decreases inversely in the region in the peripheral region.

SUMMARY OF THE INVENTION An object of the present invention is to provide a substrate for a liquid crystal display device having an improved optical transmittance without any reduction in the response speed of the liquid crystal display device between tone variations and a liquid crystal display device using the same.

The above object has a substrate in which a liquid crystal is interposed in association with an opposing substrate provided in a facing-to-face relationship, a bus line formed on the substrate, a switching element connected to the bus line, and a stripe-shaped electrode along a space therebetween. A pixel electrode connected to the switching element and provided in parallel with the bus line, wherein at least one stripe-shaped electrode in the vicinity of the bus line is formed with an electrode width narrower than the electrode width of the electrode located therein It is achieved by a substrate for a liquid crystal display device.

[First Mode for Carrying Out the Invention]

Hereinafter, a liquid crystal display substrate and a liquid crystal display device using the same in the first mode for carrying out the invention will be described with reference to FIGS. 1 to 13. The pixel electrode 3 of the liquid crystal display device in this mode for carrying out the invention has a stripe-shaped electrode 8 and a space 10 formed in parallel with the drain bus line 6 or the gate bus line 4. The stripe-shaped electrode 8 in the vicinity of the bus line is formed with an electrode width narrower than the electrode width of the stripe-shaped electrode located therein. The total area 10 of the space 10 in this mode is the total area of the electrode 3 including the stripe-shaped electrode 8 and the total area of the space 10 (the electrode area). It is characterized in that it is 50% or less of the total area).

In addition, when two separate orientations are achieved in the direction in which the drain bus line 6 extends, the stripe-shaped electrode 8 is provided only in the vicinity of the pixel peripheral region proximate the drain bus line 6. When two separation orientations are achieved in the direction in which the gate bus line 4 extends, the stripe-shaped electrode 8 is provided only in the vicinity of the pixel peripheral region proximate to the gate bus line 6 and near the boundary for orientation separation. .

The principle in which the structure of the pixel electrode 3 in this mode for carrying out the invention is determined will now be described with reference to FIGS. 1 shows a cross section of a portion of a VA-LCD taken in a direction perpendicular to the surface of the substrate. In Fig. 1, the pixel electrode 3 is formed on the glass substrate 20, which is an insulating substrate on an array substrate on which a switching element such as a TFT is formed. The pixel electrode 3 is composed of a combination of the stripe-shaped electrode 8 and the space 10, and the stripe-shaped electrode 8 and the space 10 are located in an area (not shown) in the horizontal direction in the figure. Optionally formed. In this example, the stripe-shaped electrode 8 has a width L of 3 m and the space 10 has a width S of 3 m. The common electrode 26 is provided in a relationship facing the glass substrate 20 of the array substrate, and is formed on one side of the liquid crystal layer on the glass substrate 30 of the opposing substrate via the liquid crystal layer 24.

Vertical alignment films (not shown) are formed at the interface between the glass substrates 20 and 30 and the liquid crystal layer 24. The liquid crystal layer 24 includes a liquid crystal material having negative dielectric anisotropy to which a photopolymerization monomer is added.

In the VA-LCD having such a configuration, when a voltage is applied between the stripe-shaped electrode 8 and the common electrode 26, the intensity of the electric field acting on the liquid crystal molecules 24a of the liquid crystal layer 24 is changed. The tilt angle of the liquid crystal molecules 24a depending on the electric field strength is changed to change the transmittance.

2 is a graph showing a change in transmittance as the voltage applied between the stripe-shaped electrode 8 and the common electrode 26 is changed. The positions of the stripe forming electrode 8 and the space 10 in the horizontal direction of the glass substrate 20 of the VA-LCD shown in FIG. 1 are shown on the abscissa axis. In Fig. 2, the curve indicated by the continuous symbol "◆" indicates the distribution of transmittance at an applied voltage of 3 V, and the curve indicated by the continuous symbol "Δ" indicates the distribution of transmittance at an applied voltage of 3.5 V. The curve indicated by the continuous symbol "x" indicates the distribution of transmittance at an applied voltage of 4 V, the curve indicated by the continuous symbol "□" indicates the distribution of transmittance at an applied voltage of 5.4 V, The curve indicated by the continuous symbol "-" (solid line) indicates the distribution of transmittance at an applied voltage of 10V. All of these show distribution of transmittance at 500 ms after voltage application.

As shown in Fig. 2, while the applied voltage is increased, the transmittance correspondingly increases, in some cases, the maximum value is obtained at the center of the stripe-shaped electrode 8 and the minimum value is obtained at the center of the space 10. Lose. That is, when the pixel electrode 3 is made of a combination of the stripe-shaped electrode 8 and the space 10 as shown in FIG. 1, the electric field strength and the space 10 on the stripe-shaped electrode 8 when voltage is applied. The difference in the electric field strength of the phase occurs, and the electric field strength of the space 10 phase is relatively small, and as a result, the transmittance in the vicinity of the space 10 decreases. As a result, although the dark portion X1 at the peripheral edge of the pixel electrode 3 in the vicinity of the drain bus line 6 disappears, the transmittance of the pixel as a whole does not increase. For example, in FIG. 2, the average transmittance at the time of voltage application of 5.4 V indicated by the curve indicated by the symbol " □ " is 0.784 and does not include the space 10 to be described later. The pixel electrode 3 in e.g. has an average transmittance of 0.897 (shown in FIG. 4), meaning that the "solid" structure provides high brightness because the luminance is about 14% (0.897 / 0.784 = 1.14) difference.

FIG. 3 shows a VA-LCD having a configuration identical to that shown in FIG. 1 except that the pixel electrode 3 is uniformly formed in each pixel region. 4 is a graph illustrating a change in transmittance as the voltage applied between the pixel electrode 3 and the common electrode 26 is changed. The abscissa axis represents the pixel electrode 3 corresponding to the horizontal direction of the glass substrate 20 of the VA-LCD shown in FIG. 3 and positioned substantially in the center of the pixel region. The transmittance is indicated on the ordinate axis. In Fig. 4, the curve indicated by the continuous symbol "◆" indicates the distribution of transmittance at an applied voltage of 3 V, and the curve indicated by the continuous symbol "□" indicates the distribution of transmittance at an applied voltage of 5.4 V. The curve indicated by the continuous symbol "-" (solid line) indicates the distribution of transmittance at an applied voltage of 10V. All of these show the distribution of transmittance at 500 ms time points after voltage application.

As shown in Fig. 4, while the applied voltage is increased, the transmittance correspondingly increases, and all of the distributions of the transmittance are constant regardless of the magnitude of the applied voltage, and appear the same at any position on the substrate. That is, as shown in FIG. 3, when the pixel electrode 3 has a "continuous" structure that does not include the space 10, the pixel electrode 3 has a uniform field intensity at its center when a voltage is applied. Uniform transmission can therefore be achieved.

However, as described above with reference to FIGS. 14A, 14B, and 15, when the pixel electrode 3 has a "continuous" structure that does not include the space 10, the dark portion ( Since X1) is formed at the peripheral edge of the pixel electrode 3 in the vicinity of the drain bus line 6, the overall transmittance of the pixel decreases.

In particular, although the orientation of the liquid crystal layer 24 is improved by increasing the ratio of the space 10 in the pixel electrode 3, the transmittance does not increase significantly. On the other hand, when the ratio occupied by the space 10 is too small, the orientation of the liquid crystal layer 24 becomes more irregular and the transmittance is lowered.

That is, the transmittance can be maximized by maintaining the total area of the space 10 at an optimal ratio with respect to the total area of the space 10, the stripe-shaped electrode 8 and other electrodes, or the total area of the pixel electrode 3. Empirical studies have shown that when the ratio of the space 10 is in the range of 4 to 50%, the orientation of the liquid crystal layer 24 can be improved to achieve high transmittance.

When two separate orientations are achieved in the direction in which the drain bus line 6 extends to suppress the occurrence of the dark portion X1, the stripe forming electrode 8 is at least around the pixel adjacent to the drain bus line 6. May be provided in the area. When two separate orientations are achieved in the direction in which the gate bus lines 4 extend, at least, stripe-shaped electrodes (at the periphery of the pixels proximate the gate bus lines 4 and in the vicinity of the boundary for orientation separation) 8) is provided.

Hereinafter, the liquid crystal display device in this mode for carrying out the invention will be described in detail with reference to a preferred embodiment of the invention. Common conditions applied in all the following examples are as follows.

Alignment Film: Vertical Alignment Film

Liquid crystal: Liquid crystal with negative dielectric anisotropy and photopolymerization monomer added

Polarizer: A polarizer provided on both sides of a liquid crystal panel, typically in a Nicole configuration crossed to achieve black mode.

Polarization axis of the polarizing plate: 45 degrees to the bus line

LCD panel: 15 inches in diagonal direction

Resolution: According to XGA specification.

Example 1-1

Hereinafter, Example 1-1 will be described with reference to FIGS. 5 to 7. FIG. 5 is a view showing the array substrate viewed from the normal direction of the substrate surface such that the pixel 2 of the MVA-LCD according to the present embodiment appears, and FIG. 6 is a cross sectional view of the LCD taken along the line AA of FIG. The figure shown. As shown in FIG. 5, the pixel electrode 3 has an internal electrode 12 made of an electrode material formed without the space 10 and uniformly formed inside the periphery of the pixel region. In addition, the pixel electrode 3 is formed on both sides of the electrode in parallel with the drain bus line 6, and four spaces 10 formed on both sides of the upper lower side of the connection electrode 64, and the space 10 is formed therein. It has four stripe-shaped electrodes 8 proximate the internal electrodes 12 sandwiched therebetween. Each of the stripe-shaped electrodes 8 is electrically connected to the internal electrodes 12 through connection electrodes 64 formed substantially in the center of the pixels 2 in the vertical direction. The upper left portion of the internal electrode 12 is connected to the source electrode 62 of the TFT 16.

In this embodiment, the stripe-shaped electrode 8 has a width L of 3 mu m, and the space 10 has a width S of 3 mu m. The total area of the space 10 of the present embodiment is 6% of the total area of the pixel electrode, which is the sum of the areas of the space 10, the stripe-shaped electrode 8, and the other electrodes (the inner electrode 12 and the connecting electrode 64). Occupy.

As shown in Fig. 6, a linear projection 66 extending in parallel with the gate bus line 4 is formed on an opposing substrate provided at a position in a relationship facing the connection electrode 64 at the center of the pixel region. The alignment direction of the liquid crystal molecules 24a may be more strongly determined by the linear protrusions 66.

Instead of providing the linear protrusions 66 on the opposing substrate, a rubbing process may be performed on the array substrate or the alignment film on the opposing substrate. In this case, as indicated by the arrows shown in FIG. 6, both regions B and C of the array substrate shown in FIG. 5 are rubbed toward the center of the pixel electrode 3 in parallel with the drain bus line 6. The opposing substrate is rubbed in the direction away from the connecting electrode 64. Optionally, an optical alignment method using UV light may be employed.

The orientation of the liquid crystal molecules 24b in the region A surrounded by the dotted lines in the vicinity of the TFT 16 shown in FIG. 5 is deformed, and as shown in FIG. 6, in the direction opposite to the liquid crystal molecules 24a in the region B. As shown in FIG. The molecule may be tilted. As a result of this irregular orientation, dark portions may be formed in the region A when a voltage is applied to the liquid crystal layer 24. 7 shows modifications to alleviate this problem. In this modification, two linear projections 68 extending in parallel with the gate bus line 4 are oriented in the vicinity of both ends of the pixel electrode 3 proximate the gate bus line 4 as shown in FIG. 7. It is formed as an adjustment structure. By adding a linear projection 68 between the gate bus line 4 and the pixel electrode 3 while on the gate bus line, the tilt direction of the liquid crystal molecules 24b in the region A is changed to the liquid crystal molecules 24a in the region B. Can be the same as the tilt direction. Cutouts (slits) at the electrodes may be used as an orientation adjusting structure by forming the electrodes with partial cutouts.

A voltage is applied to the liquid crystal layer 24 using the modified structure of FIG. 7 (the gate electrode is 30 Vdc, the drain electrode is -5 Vdc, and the common electrode is at ground potential), so that the liquid crystal in the pixel 2 in a predetermined direction. The molecule 24a is tilted, and in the same state, light is irradiated to the liquid crystal to which the photopolymerization monomer is added to polymerize the monomer, thereby fixing the pretilt angle and / or the orientation direction of the liquid crystal molecule 24a. When the completed MVA-LCD is driven for display and the display area is observed, light is transmitted through the entire pixel area, indicating that the present LCD has better transmittance than the conventional LCD.

As described above, in the present embodiment, the stripe-shaped electrode 8 is formed in the peripheral region of the pixel proximate to the drain bus line 6 when two separate orientations are achieved in the direction in which the drain bus line 6 extends. It is provided on both sides, and the space 10 occupies 6% of an area. This makes it possible to achieve the preferred orientation and high transmittance of the liquid crystal layer 24.

Example 1-2

Hereinafter, Example 1-2 will be described with reference to FIG. 8. 8 is a view showing the array substrate seen from the normal direction of the substrate surface so that the pixels of the MVA-LCD according to the present embodiment appear. This embodiment is identical in configuration to Embodiment 1-1 except for the structure of the pixel electrode 3. The pixel electrode of this embodiment is different from the structure of the pixel electrode 3 of the embodiment 1-1 shown in Fig. 5, on both sides of the electrode in parallel with a total of eight spaces 10, i.e., the drain bus line 6; Two spaces 10 are formed on both sides of the upper and lower portions of the connecting electrode 64, respectively, and are associated with eight stripe-shaped electrodes 8, that is, paired spaces 10 adjacent to the internal electrodes 12. Two electrodes 8 are formed, respectively.

The total area of the space 10 in this embodiment is twice the total area of the embodiment 1-1 and occupies 12% of the total area of the pixel electrode 3.

Therefore, as described above, the plurality of stripe-shaped electrodes 8 are provided on both sides of the peripheral region of the pixel proximate to the drain bus line 6 of the present embodiment, and are separated in two in the direction in which the drain bus line 6 extends. Orientation is achieved and space 10 occupies 12% of the total area. This makes it possible to achieve the preferred orientation of the liquid crystal layer 24 and to achieve high transmittance.

Example 1-3

Hereinafter, Embodiments 1-3 will be described with reference to FIG. 9. FIG. 9 is a view showing the array substrate seen from the normal direction of the substrate surface such that the pixel 2 of the MVA-LCD according to the present embodiment appears. This embodiment is identical in configuration to Embodiment 1-1 except for the structure of the pixel electrode 3. Unlike the structure of the pixel electrode 3 of the embodiment 1-1 shown in FIG. 5, the pixel electrode 3 of the present embodiment has the height of the internal electrode in FIG. 5 in the extending direction of the drain bus line 6. A lower internal electrode 12 'is provided, and a region in which the stripe-shaped electrode 8' and the space 10 'of the line and space configuration are provided by lowering the height of the electrode is provided.

In this structure, the total area of the spaces 10 and 10 'of this embodiment occupies 35% of the total area of the pixel electrode 3.

As described above, the plurality of stripe-shaped electrodes 8 are provided on both sides of the peripheral region of the pixel proximate to the drain bus line 6 in this embodiment, so that the two stripe electrodes 8 are extended in the direction in which the drain bus line 6 extends. Separation orientation is achieved and space 10 occupies 35% of the total area. This allows to achieve the desired orientation of the liquid crystal layer 24 and to achieve high transmittance.

Example 1-4

Hereinafter, Examples 1-4 will be described with reference to FIGS. 10 to 13. FIG. 10 is a view showing the array substrate viewed from the normal direction of the substrate surface such that the pixels 2 of the MVA-LCD according to the present embodiment appear. The structure of the pixel electrode 3 according to the present embodiment is characterized in that the stripe-shaped electrode is formed in parallel with the gate bus line 4. In order to separate the orientation in the two horizontal directions in FIG. 10, one stripe-shaped electrode 8 in the upper half of the pixel connected to the source electrode 62 of the TFT 16 has a space 10 interposed therebetween. It is connected to the internal electrode 12a in the upper part of the figure through the connecting electrode 64a in the upper right part of the drawing, and the striped electrode 8 in the lower half of the pixel is connected to the connecting electrode 64d in the lower left part of the drawing. The space 10 is sandwiched between and connected to the internal electrode 12b at the bottom of the figure. The internal electrode 12a is connected to the stripe-shaped electrode 8 'with the spaces 10 on both sides via the connection electrode 64b positioned on the right side thereof, and connects the connection electrode 64c positioned on the left side thereof. The internal electrode 12b is connected through this.

This makes it possible to actively use the orientation of the liquid crystal molecules inclined in the direction orthogonal to the drain bus line 6 by the transverse electric field generated at the end of the pixel electrode in parallel with the drain bus line 6. It is apparent that the positions of the connection electrodes 64a to 64d may be reversed so that the structure of the pixel electrode 3 is reversed in the horizontal direction of FIG. 10. In this resulting structure, the total area of the space 10 in the present embodiment occupies 4% of the total area of the pixel electrode 3.

As described above, in this embodiment, in order to achieve two separate orientations in the extending direction of the gate bus line 4, the stripe-shaped electrode 8 is arranged at least around the periphery of the pixel close to the gate bus line 4. A stripe-shaped electrode 8 'is provided in the vicinity of the boundary (position where the two internal electrodes 12a and 12b face each other) for orientation separation, and the space 10 covers 4% of the total area. Occupy. This makes it possible to achieve the preferred orientation of the liquid crystal layer 24 and to achieve high transmittance.

FIG. 11 is a cross-sectional view taken along the line B-B of FIG. 10. FIG. 12 is a cross-sectional view taken along the line C-C of FIG. 10. As shown in Figs. 11 and 12, the linear projection 66 is formed on the opposing substrate between the connecting electrodes 64a and 64d and the drain bus line 6 located adjacent thereto. By forming the linear projections 66, it is possible to eliminate the influence of the electric field between the internal electrodes 12a and 12b proximate the connection electrodes 64a and 64d and the edges of the drain bus line 6 proximate thereto. . A rubbing process or a photo alignment process may be performed to further improve the reliability of the alignment direction.

13 is a view showing a modification of the present embodiment. As shown in FIG. 13, the linear protrusion 68 may be provided to the array substrate in the vicinity of each of the left end of the inner electrode 12a and the right end of the inner electrode 12b in the drawing. By forming the linear projections 68, it is possible to eliminate the influence of the electric field between the vicinity of the left end of the internal electrode 12a and the right end of the internal electrode 12b and the drain bus line 6 adjacent thereto in the drawing. do.

In this structure, a voltage is applied to the liquid crystal layer 24 so that the monomers in the liquid crystal layer 24 polymerize. Thus, the completed MVA-LCD is hardly affected by the electric field generated between the edges of the pixels when displaying an image because the direction of inclination of the liquid crystal molecules 24a is determined by the resulting polymer. When driving the MVA-LCD for display and observing the display area, it can be seen that the light is transmitted through the entire pixel area so that the transmittance is improved as compared with the conventional LCD.

[Second Mode for Carrying Out the Invention]

Hereinafter, the liquid crystal display substrate and the liquid crystal display device using the same in the second mode for carrying out the present invention will be described with reference to FIGS. 18 to 20B. In the first mode for carrying out the invention, as described with reference to FIG. 5, the dark line is surrounded by a dotted line representing a connection portion between the source electrode 62 and the stripe-shaped electrode 8 of the TFT 16. It is generated at the boundary between the liquid crystal molecules 24a inclined in the positive direction and the liquid crystal molecules 24b inclined in the opposite direction in the true region A. This phenomenon also occurs in the proposed structure of the pixel electrode shown in Figs. 16 and 17 (see liquid crystal molecules 24b in Fig. 17). The generation of dark lines is prevented by providing the linear protrusions 68 on the array substrate in the first mode for carrying out the invention, but will now be discussed whether the linear protrusions 68 can be made without.

When the linear protrusion 68 is not provided, since there is no electric field for determining the position where the dark line is generated, the region of the liquid crystal molecules 24b inclined in the opposite direction can be arbitrarily expanded. This results in the operation of taking out the liquid crystal molecules 24a '(not shown) inclined in the direction orthogonal to the drain bus line 6 in the vicinity of the bus lines from the black matrix area toward the display area, and thus the liquid crystal molecules ( An area where 24a ') exists is formed between the periphery of the pixel and the drain bus line 6. As a result, the dark line X1, which is located near the drain bus line 6 and outside the display area, expands, and as shown in the enlarged photograph of the pixel in FIG. Appears in the vicinity of 6).

In this mode for carrying out the invention, in order to solve the above-mentioned problem, the liquid crystal molecules 24a and the source electrode 62 which are inclined in the direction orthogonal to the drain bus line 6 in the vicinity of the drain bus line 6. ) And a configuration for removing the interaction between the liquid crystal molecules 24b inclined in the opposite direction in the vicinity of the connecting portion between the stripe-shaped electrodes.

Hereinafter, a liquid crystal display device in this mode for carrying out the invention will be described with reference to Examples.

Example 2-1

Hereinafter, Example 2-1 will be described with reference to FIGS. 19A and 19B. FIG. 19A is a view of the pixel 2 of the MVA-LCD having two separate alignment regions as viewed from the normal direction of the substrate surface. 19B is an enlarged view showing the MVA-LCD taken in the normal direction of the substrate surface. As shown in Fig. 19A, each of the stripe forming electrode 9 and the space 10 is formed between the drain bus line 6 and the TFT 16 in this embodiment.

Further, in order to prevent the liquid crystal molecules 24b from inclining in the opposite direction, the stripe-shaped electrode 8 positioned at the center of the connection portion between the source electrode 62 and the stripe-shaped electrode 8 of the TFT 16 is provided. The vicinity of the connecting portion is cut so as to form a gap 11 between the end of the source electrode 62 and the stripe-shaped electrode 8.

When one or more stripe-shaped electrodes 9 and spaces 10 are formed between the bus lines 6 and the TFTs 16, the stripe-shaped electrodes 9 are formed of the drain bus lines 6 on the pixel electrodes 3. The liquid crystal molecules 24a in the vicinity are inclined in a direction parallel to the longitudinal direction of the space 10. This eliminates the interaction between the alignment of the liquid crystal molecules 24a inclined in the direction orthogonal to the drain bus line 6 and the alignment of the liquid crystal molecules 24b inclined in the opposite direction near the source electrode 62 of the TFT 16. To be possible. As a result, the dark line X1 near the drain bus line 6 can be held in the black matrix outside of the display area.

In addition, the gap 11 is formed by cutting at least a portion of the stripe-shaped electrode 8 at the connection portion between the source electrode 62 and the pixel electrode 3 of the TFT 16, so that a new shape of the stripe-shaped electrode 8 The same effect as that by the formation of the end can be obtained. This makes it possible to minimize the dark line X1 and maintain the position of the dark line in the black matrix outside of the display area.

Since dark lines X1 are frequently generated by bead spacers or the like for maintaining cell gaps between substrates serving as kernels, the spacers for maintaining gaps are provided instead of the cylindrical spacers outside the display area. It is desirable to.

If the width L of the stripe-shaped electrodes 8 and 9 is too small, the electrodes can be destroyed. If the width is too large, the liquid crystal module 24a is not inclined in parallel with the longitudinal direction of the space 10. If the width S of the spacer is too small, a short circuit may occur between the stripe-shaped electrodes 8 and 9. If the width is too large, the liquid crystal molecules 24a do not incline in the longitudinal direction of the space 10. Therefore, it is preferable to set the width L of the stripe-shaped electrodes 8 and 9 and the width S of the space 10 within a range between 0.5 m and 5 m.

Similarly, the width of the gap 11 (distance between the source electrode 62 facing each other and the end of the stripe-shaped electrode 8) is preferably set within the range of 0.5 µm and 5 µm.

In this embodiment and the following examples, a vertical alignment film is used, the liquid crystal has negative dielectric anisotropy, and since the polarizing plate is provided on both sides of the liquid crystal panel in a cross nicol configuration, it is in black mode in normal state, and the polarization axis of the polarizing plate is a bus line About 45 degrees. The panel size is 15 inches and the resolution depends on the XGA characteristics.

Example 2-2

Hereinafter, Example 2-2 will be described with reference to FIGS. 20A and 20B. FIG. 20A shows a view of the pixel 2 of the MVA-LCD having two separate alignment regions seen in the normal direction of the substrate surface. 20B shows an enlarged view of the MVA-LCD taken in the normal direction of the substrate surface. As shown in Fig. 20A, in this embodiment, each of the stripe-shaped electrodes 9 and the spaces 10 is formed between the drain bus line 6 and the TFT 16, similarly to the embodiment 2-1. Is formed.

In addition, in order to prevent the liquid crystal molecules 24b from inclining in the opposite direction, two stripe electrodes 8 positioned on both sides of the connection portion between the source electrode 62 and the stripe electrode 8 of the TFT 16. ) Is cut off in the vicinity of the connecting portion so that two gaps 11a and 11b are formed between the end of the source electrode 62 and the stripe-shaped electrode 8.

In this configuration, the stripe-shaped electrode 9 causes the liquid crystal molecules 24a in the vicinity of the drain bus line 6 on the pixel electrode 3 to be inclined in a direction parallel to the longitudinal direction of the space 10. This is due to the interaction between the alignment of the liquid crystal molecules 24a inclined in the direction orthogonal to the drain bus line 6 and the orientation of the liquid crystal molecules 24b inclined in the opposite direction in the vicinity of the source electrode 62 of the TFT 16. To be removed.

In addition, the shape of the gaps 11a and 11b provides the same effect as the shape of the two new ends of the stripe-shaped electrode 8, the occurrence of dark lines is minimized, and their positions are the black matrix outside the display area. Can be maintained within.

In this embodiment, the columnar spacers for holding the cell gap are preferably provided outside the display area as in the embodiment 2-1. In addition, it is preferable that the width L of the stripe-shaped electrodes 8 and 9 and the width S of the space 10 be set within a range between 0.5 µm and 5 µm. Similarly, the width of each of the gaps 11a and 11b is preferably set within a range between 0.5 μm and 5 μm.

[Third Mode for Carrying Out the Invention]

Hereinafter, a liquid crystal display substrate and a liquid crystal display device using the same in the third mode for carrying out the invention will be described with reference to FIGS. 21 to 26. Fig. 21 is a diagram schematically showing a cross section of the MVA-LCD in this mode for carrying out the invention taken in a direction perpendicular to the substrate surface. 22 to 26 show a state near the alignment layer 32. As shown in FIG. 21 and FIG. 22, the polymer layer 36 is formed on the alignment films 32 and 34 provided on the pixel electrode 3 and the common electrode 26, respectively. As indicated by the curve 38 showing the change in the orientation direction in FIG. 23, the direction of the molecules of the polymer in the polymer layer 36 is perpendicular to the surface of the vertical alignment film, and at an angle θp relative to the vertical on the surface of the liquid crystal. Inclined in direction.

Thus, the polymer layer 36 determines the orientation direction of the liquid crystal molecules 24a in the gap between the linear protrusions 66 and 68 having the alignment adjustment structure shown in FIG. 21. In particular, since the alignment direction of the liquid crystal molecules 24a is also determined in the gaps between the structures, the response time may decrease when halftones are displayed, and the transmittance is improved because the irregularity of the alignment of the liquid crystals decreases. Can be.

Hereinafter, the liquid crystal display in this mode for carrying out the invention will be described with reference to FIGS. 21 to 26 again.

In FIG. 21, the pixel electrode 3 and the common electrode 26 are formed of a transparent material for the pixel electrode such as ITO. Linear projections (bank-shaped alignment adjusting structures) 66 and 68 having a height of 1.5 mu m and a width of 10 mu m are formed on the pixel electrode 3 and the common electrode 26. As shown in FIG. The gap between the linear protrusions 66 and 68 is 25 mu m. The vertical alignment films 32 and 34 are formed on the pixel electrode 3 and the common electrode 26 and on the linear projections 66 and 68, respectively. The negative liquid crystal layer 24 having a thickness of about 4 μm is sealed between the vertical alignment films 32 and 34 in a relationship facing each other. The liquid crystal layer molecules 24a are inclined in the direction of the angle θp as described. The surface of the vertical alignment films 32 and 34 was not subjected to any processing such as a rubbing process or an optical alignment process.

22 is a diagram showing a polymer layer 36 formed on the vertical alignment layer 32. Although not shown, the same polymer layer 36 is also formed on the vertical alignment film 34 on the opposing substrate. FIG. 23 is a diagram showing the polymer layer 36 formed on the surface of the vertical alignment film 32 to pretilt the liquid crystal molecules 24a at an angle θp with respect to the liquid crystal layer 24. As can be clearly seen from the curve 38 showing the change in the orientation direction, the polymer in the polymer layer 36 is inclined on the top surface of the layer in contact with the liquid crystal layer 24, so that the liquid crystal molecules 24a It may be pretilted in the gap between the linear protrusions 66 and 68. The polymer has a large surface energy because irregularities appear on the surface of the polymer layer 36 as shown in FIG. When the polymer layer has a thickness of more than 5000 kPa, a large voltage drop occurs in the polymer layer 36, so that the driving voltage does not actually increase. On the contrary, when the said thickness is less than 10 microseconds, sufficient orientation adjustment force cannot be obtained.

The polymer layer 36 shown in FIG. 23 has a polymerization initiator of 0.3% by weight of alkoxylyl and a monomer having a liquid crystal stem doped to the negative liquid crystal, and has an energy of 2J and an illuminance of 20 mW / cm 2 while applying a voltage thereto. It is formed by polymerizing a monomer using light. Observation using an AFM (atomic force microscope) and a TEM shows that a polymer layer 36 having a thickness of about 100 GPa is formed on the surface of the vertical alignment film 32 when the vertical alignment film is used as the alignment film 32. Can be. As a result of the actual measurement of the retardation (Δn d) of the polymer using an ellipsometer, the polymer was oriented in the alignment direction of the liquid crystal and a stable orientation of the liquid crystal was observed at retardation of 0.01 nm or more.

24 is a schematic diagram showing a locally formed polymer layer 36. As mentioned above, when the monomer is added to a small dose (up to about 0.5 wt.%) Or slowly cured (using a UV light source of up to about 50 mW), the polymer layer may be formed on or over the entire alignment layer. It may be formed locally. In addition, the polymer may be oriented in the direction of the liquid crystal by polymerizing while applying an electric field to provide a retardation. Inclined liquid crystal alignment can be achieved by providing such a retardation. Network polymers can be included when large amounts of monomers are used.

FIG. 25 is a diagram showing the polymer layer 36 formed when the alignment films 32 and 34 are horizontal alignment films. The layer is formed by adding a monomer to the positive liquid crystal and polymerizing it while applying a voltage. As indicated by the curve 38 showing the change in the orientation direction in FIG. 25, the orientation of the polymer molecules in the polymer layer 36 is horizontal on the surface of the horizontal alignment film 32, and It is inclined in a predetermined angle direction on the surface. The polymer is pretilted such that the liquid crystal is tilted uniformly as a whole.

FIG. 26 is a diagram showing the film polymer layer 36 formed on the horizontal alignment film 3. As indicated by the curve 38 showing the change in the orientation direction, the orientation of the polymer molecules in the polymer layer 36 is horizontal on the horizontal alignment film, which molecules can be made almost perpendicular to the surface of the liquid crystal. . This polymer layer 36 may also be provided by polymerizing monomers in the horizontal alignment layer 32. Optionally, this may be provided by forming side chains in the monomers.

While the linear projections are used as the orientation adjusting structure in this mode for carrying out the invention, it is apparent that partition walls, slits, fine slits, rubbed alignment films and the like can be used. Alternatively, the polymer layer may itself be formed on a substrate having a vertical or horizontal orientation instead of using an alignment film. The polymer in this mode for carrying out the invention may be used to fix the orientation of ferroelectric liquid crystals, such as smectic liquid crystals.

As described above, in this mode for carrying out the invention, the liquid crystal can be stably oriented on the entire surface of the substrate since a polymer layer defining the orientation direction can be formed between the locally provided alignment adjustment structures. Can be. This shortens the response time for halftones and makes it possible to achieve high transmittance.

[Fourth Mode for Carrying Out the Invention]

Hereinafter, with reference to FIGS. 27A to 34, a substrate for a liquid crystal display device and a liquid crystal display device using the same in the fourth mode for carrying out the invention will be described. Prior art will be described before describing the present mode for carrying out the invention. In a previous application filed by the present applicant (Japanese Patent Laid-Open No. 2001-264117 filed on August 31, 2001), lines and spaces as pixel electrodes 3 on an array substrate on which TFTs 16 are formed are provided. It is proposed to provide a stripe-shaped electrode in the configuration. 27 (a), 27 (b), and 28 show the alignment adjustment structure proposed in the cited application. As shown in Figs. 27A, 27B, and 28, using a stripe-shaped electrode 8 and a space 10 in which a stripe having a width of several micrometers formed on a substrate is repeated. A configuration is proposed in which the liquid crystal molecules 24a are oriented parallel to the longitudinal direction of the stripe-shaped electrode 8 and the space 10, whereby the number of boundaries between the separation orientations in the pixels is minimized.

If the electrode width L of the stripe-shaped electrode 8 is slightly changed due to the variation in the photolithography process, the TV (transmittance versus applied voltage) characteristics of the liquid crystal display may change and appear as unevenness in the display. There is a problem that can be. In the above-mentioned application, as a solution to this problem, it is proposed to make the electrode width L of the stripe-shaped electrode 8 equal to or wider than the width S of the space 10. In order to control the liquid crystal of the panel using the stripe-shaped electrodes 8 and the spaces 10 so as to be oriented in a plurality of directions, for example, stripe shapes are oriented in a plurality of directions as shown in FIGS. 29 and 30. It is necessary to use a (fish bone) pattern, which is a combination of the electrode 8 and the space 10. 31A to 31D show the relationship between the electrode width L of the stripe-shaped electrode 8 and the width S of the space 10 and the orientation during halftone display, The result of the embodiment performed at the boundary between the stripe-shaped electrode 8 and the space 10 (the spine portion of the fishbone pattern) is shown. As shown in Figs. 31A to 31D, when L is narrower than S, it can be seen that the orientation at the boundary is more stable. This relationship is opposite to the relationship between the electrode width L of the stripe-shaped electrode 8 and the width S of the space 10 proposed in the above-described application. This result was observed before the monomer in the liquid crystal was polymerized, and this problem can be almost avoided by applying a sufficiently high voltage during the polymerization. However, this problem may occur when the orientation is achieved only by the stripe-shaped electrode 8 and the space 10 without using a method of fixing through polymerization, or when the polymerization voltage is lowered. It is desirable to achieve more stable orientation in both the region formed by 8) and the space 10 and the boundary.

The principle in this mode for carrying out the invention is shown in FIG. As shown in FIG. 32, the stripe-shaped electrode 8 and the space 10 have different electrode widths L and space widths S in the vicinity of the boundary (backbone) and in the region spaced from the boundary. In particular, the electrode width L is narrower than the space width S in the vicinity of the boundary, and the electrode width L is wider than the space width S in the region spaced from the boundary. This makes it possible to fix the orientation of the liquid crystal on both sides of the region near the boundary and the region spaced from the boundary, so that the unevenness of the display can be reduced.

A liquid crystal display device in this mode for carrying out the invention will be described below with reference to the following Examples.

Example 4-1

Embodiment 4-1 will be described with reference to FIG. 33.

A 15 inch size XGA panel (with 1024 × 768 pixels at a pixel pitch of 297 μm) was made. 33 shows one of the pixels of the panel. The TFT 16, the gate bus line 4, the drain bus line 6, and the pixel electrode 3 composed of the stripe-shaped electrode 8 and the space 10 are formed on one substrate. The color filter layer and the common electrode are formed on another substrate. A glass substrate (OA-2) (manufactured by Nippon Electric Glass Co., Ltd.) having a thickness of 0.7 mm was used as the substrate. The stripe-shaped electrode 8 extends from the center of the pixel in four directions (to the upper right, lower right, upper left and lower left corners of the pixel).

The electrode width L of the stripe-shaped electrode 8 and the width S of the space 10 were 2 m and 4 m, respectively, in the vicinity of the boundary (backbone) between them, and the electrode width of the stripe-shaped electrode 8 The width S of (L) and the space 10 was 4 µm and 2 µm, respectively, in the region spaced from the boundary. The distance X between the position where the pattern width of the stripe-shaped electrode 8 was changed and the edge of the boundary was 5 m.

These substrates were formed with a vertical alignment film made of polyimide material using a printing process and subjected to heat treatment at 180 ° C. for 60 minutes. In addition, the substrate was bonded to the spacer having a diameter of 4㎛ sandwiched therebetween to produce an open cell in which no liquid crystal was injected therein. A liquid crystal panel with negative dielectric anisotropy added with a very small amount of photopolymerization monomer was injected into the cell to prepare a liquid crystal panel. The amount of added photopolymerization monomer was 2.4% by weight. Thereafter, the liquid crystal panel was irradiated with ultraviolet rays while a voltage was applied thereto to polymerize the monomers. This applied voltage was 10 V and the dose of ultraviolet light was 2000 mJ / cm 2 (λ = 365 nm).

Example 4-2

Hereinafter, Example 4-2 will be described with reference to FIG. 34. This embodiment is the same as Example 4-1 except the following conditions. The electrode width of the stripe-shaped electrode 8 was continuously changed from the width in the vicinity of the boundary to the width in the area spaced therefrom. This also provides the same effects as in Example 4-1.

As described above, this mode for carrying out the invention improves the display characteristics of the liquid crystal display device in which the pretilt angle of the liquid crystal molecules and the tilt direction thereof are determined by using a polymerization material which is thermally or optically polymerized when voltage is applied. To be able.

[Fifth Mode for Carrying Out the Invention]

Hereinafter, a liquid crystal display substrate and a liquid crystal display device using the same in a fifth mode for carrying out the invention will be described.

Displayed when a liquid crystal layer containing a thermal or optical polymerization monomer is sealed between the substrates, the polymerization component is polymerized with a voltage applied to the liquid crystal layer to fix the alignment of the liquid crystal, and the same image is displayed continuously for a long time. Image sticking may occur in which the previous image remaining after the change of becomes a subsequent image, and the purpose of this mode for carrying out the invention is to prevent image sticking resulting from the polymer fixing method.

As a result of the empirical studies, it has been found that image sticking can be prevented when the molecular weight of the added monomer is almost 1.5 times or less than the average molecular weight of the liquid crystal component. In particular, it has been found that the effect of preventing image sticking can be obtained when the molecular weight of the monomer is almost equal to or smaller than the average molecular weight of the liquid crystal component. It has also been found that image sticking can be prevented when the molecular weight of the polymerization initiator is approximately equal to or less than the average molecular weight of the liquid crystal component. It demonstrates in detail below.

In order to solve image sticking in a polymer fixed liquid crystal display device, various monomers, a polymerization initiator, and a liquid crystal component were tested, and as a result, the following facts were found.

It is assumed that M _lc represents the molecular weight of the liquid crystal component, M _m represents the molecular weight of the monomer, and M _ini represents the molecular weight of the polymerization initiator.

(i) The molecular weight M _m decreases as the image sticking rate decreases. In particular, the image sticking rate decreases when the molecular weight M _m is about equal to or less than the molecular weight M _lc .

(ii) As the image sticking rate decreases, the molecular weight M _ini becomes smaller. In particular, the image sticking rate decreases when the molecular weight M _ini is about equal to or less than the molecular weight M _lc .

(iii) Preferred monomer densities are in the range of 0.1 to 10% by weight from the viewpoint of image sticking. In particular, a density of about 0.3% by weight is preferred.

(iv) The polymerization initiator needs to reduce the optimal dose of ultraviolet rays in order to improve the production efficiency. However, when the density of the initiator is too high, the image sticking rate increases. The preferred density of the polymerization initiator is in the range of 0.1 to 10% by weight. In particular, a density of about 2% by weight is preferred.

The image sticking rate is obtained as follows. The black white check pattern is displayed on the display area of the LCD for a long time. A predetermined halftone is displayed all over the display area immediately after displaying the pattern. The luminance difference is obtained between the area where white is displayed and the area where black is displayed, and this luminance difference is divided by the luminance of the area where black is displayed to obtain an image sticking rate.

Hereinafter, the liquid crystal display in this mode for implementing the invention will be described with reference to Examples and Comparative Examples. In all the following embodiments, a vertical alignment layer is used, and since the liquid crystal has negative dielectric anisotropy and polarizing plates are provided on both sides of the liquid crystal panel in a crossed Nicole configuration, the display is in black mode in a normal state, and the polarization axis of the polarizing plate is connected to the bus line. 45 degrees relative to the panel, the panel size is 15 inches, the resolution is in accordance with the characteristics of the XGA.

Example 5-1

Polymer fixed LCDs were prepared using a liquid crystal material obtained by mixing a liquid crystal component having an average molecular weight of about 350 with 0.3% by weight of a diacrylate monomer, which diacrylate monomer has a molecular weight of about 350. The image sticking rate of the LCD was 5% after display for 48 hours.

Comparative Example 5-1

Polymer fixed LCDs were prepared using a liquid crystal material obtained by mixing a liquid crystal component having an average molecular weight of about 350 with 0.3% by weight of a diacrylate monomer, which diacrylate monomer has a molecular weight of about 700. The image sticking rate of the LCD was 30% after display for about 48 hours.

Example 5-2

5% by weight of polymerization initiator was added to the diacrylate monomer having a molecular weight of about 350, and the initiator had a molecular weight of about 260. Polymer fixed LCDs were prepared using a liquid crystal material obtained by mixing a liquid crystal component having an average molecular weight of about 350 with a diacrylate monomer containing a polymerization initiator in an amount of 0.3% by weight. The image sticking rate of the LCD was 0.3% after display for 48 hours. In the present embodiment, the dose of ultraviolet rays required to achieve the predetermined tilt angle is one tenth of the dose in Example 5-1.

Comparative Example 5-2

5 wt% of a polymerization initiator was added to the diacrylate having a molecular weight of about 350, which had a molecular weight of about 350. Polymer fixed LCDs were prepared using a liquid crystal material obtained by mixing a liquid crystal component having an average molecular weight of about 350 with a diacrylate monomer containing a polymerization initiator in an amount of 0.3% by weight. The image sticking rate of the LCD was 10% after display for 48 hours.

Example 5-3

A polymer fixed LCD was produced using a liquid crystal material obtained by mixing 3 weight percent diacrylate monomer with a liquid crystal component having an average molecular weight of about 350, which diacrylate monomer has a molecular weight of about 350. The LCD became stable after annealing at 120 ° C. for 2 hours.

[Sixth Mode for Carrying Out the Invention]

Hereinafter, a liquid crystal display in a sixth mode for carrying out the invention will be described with reference to FIGS. 35 to 43. A polymer stabilized liquid crystal panel (Japanese Patent Laid-Open No. 148122/1994) or a ferroelectric liquid crystal (SID'96 Digest, p.699) using an amorphous TN liquid crystal has been reported. Hereinafter, the related art will be described with reference to, for example, an amorphous TN liquid crystal. Diacrylate resin is added to the liquid crystal containing a predetermined chiral material, and the liquid crystal is injected into the empty panel. The liquid crystal layer is irradiated by ultraviolet light while voltage is applied, which is effective in both aspects of eliminating defects in alignment and controlling the number of defects due to voltage application. This makes it possible to eliminate the defects of hysteresis and instability of the amorphous TN liquid crystal, which has been a problem in the related art. What is important in achieving fixing using a polymer is to polymerize the photocurable resin in the liquid crystal layer by irradiating ultraviolet light while applying a voltage to the liquid crystal layer to align the liquid crystal molecules in a predetermined direction.

This mode for carrying out the invention is based on the related prior art described above, and can be further improved to apply the related prior art to LCDs employing other display methods and structures, thereby further improving the reliability of the polymer fixing method. To provide technology. Image sticking can be performed to form multiple domains in an in-plane switching liquid crystal display (IPS-LCD), to improve display characteristics (contrast, etc.) of reflective and transmissive reflective liquid crystal displays, and to improve the reliability of the polymerization method. The suppression of undesirably remaining displayed patterns, as the orientation of the liquid crystal changes slightly with energyification, will be described in detail with reference to the examples.

Example 6-1

35 is a view showing the configuration of the display electrode and the common electrode of the related art IPS-LCD. Like the TN method, a rubbing process is necessary to implement the IPS method to orient the liquid crystal in the horizontal direction. When a horizontal alignment film (e.g., JALS-1954 manufactured by Japan Synthetic Resin Co., Ltd.) is used as an orientation material for providing an initial orientation having an angle with respect to an electric field, whereby a voltage is applied Deformation in the direction of orientation easily occurs and deformation in a uniform amount occurs. Although IPS-LCDs are specified with a wide viewing angle even in a single domain structure (there is one domain with a single orientation in pixels), it is necessary to form multiple domains to provide a wider wide viewing angle. For this purpose, as shown in FIG. 35, two domains are provided by forming the display electrode 70 and the common electrode 26 provided in a chevron structure (V type structure) facing each other on the same substrate. Technology has been developed. In the same structure, the orientation of the liquid crystal molecules 24a is separated to form two domains upon application of voltage, as shown in FIG. However, the display electrode 70 and the common electrode 26 are bent in the plane of the substrate in this structure, so that the transmittance is further reduced.

36 shows an electrode structure of an IPS-LCD according to the present embodiment. Instead of the chevron structure as shown in FIG. 35, the electrode structure of this embodiment has the same linear display electrode 70 and common electrode 26 as ellipses alpha and alpha 2 in FIG. As shown is a partially inclined electrode structure that is bent at an angle to the substrate plane at its end. The liquid crystal molecules 24a in the ellipses α1 and α2 are almost symmetrically rotated with respect to the centerline of the common electrode 26 in the longitudinal direction when voltage is applied, and this rotation is transmitted to other liquid crystal molecules 24a in the same domain. Two domains are formed. This structure makes it possible to produce two domain panels that are stable in combination with the polymer fixation method. According to the polymer fixing, after the alignment of the liquid crystal enters the steady state, the monomers are polymerized to form a polymer. After polymerization, the orientation of the liquid crystal is stabilized even during transient response. Although the above description is made based on the assumption that the liquid crystal has positive dielectric anisotropy, the same applies to negative dielectric anisotropy if the direction of the alignment process is changed by about 90 degrees.

Example 6-2

37 is a diagram showing a reflective LCD according to the present embodiment. In a reflective LCD, a reflective electrode 72 having an uneven shape is used to achieve display quality close to paper white without parallax. However, the liquid crystal orientation will be deformed because the reflective electrode 72 acts as a kernel when compared with the flat reflective electrode, resulting in irregularities. When the rubbing process is performed, an orientation defect may occur because the orientation process is not sufficiently performed at the bottom of the irregular surface. When the polymer layer 36 is formed on the reflective electrode 72 in this state by the polymerization technique as shown in Fig. 37, since a preferable uniform orientation is achieved and stored by the polymerization layer 36, It is possible to sufficiently suppress the occurrence of disordered orientation due to deformation to the orientation which has been frequently observed in the prior art.

In Fig. 37, the common electrode 26 is formed of a transparent material for pixel electrodes such as ITO. The alignment films 32 and 34 are formed on the reflective electrode 72 and the common electrode 26, respectively. The liquid crystal layer 24 is sealed between the alignment films 32 and 34 in a facing relationship. The polymer layer 36 is formed on the alignment films 32 and 34. The polymer in the polymer layer 36 is inclined on the top surface of the layer in contact with the liquid crystal layer 24, whereby the liquid crystal molecules 24a can be pretilted.

Example 6-3

38 and 39 show a transmissive reflective LCD according to the present embodiment. The transmissive reflective LCD has a light transmitting portion and a light reflecting portion, so that a desirable display can be achieved irrespective of the luminance of the surrounding illumination. In the transmissive reflective LCD, the amount of change in the retardation in the light transmitting part contributing to the rotation (switching) of the liquid crystal molecules should be switched so that the amount of change in the retardation of the liquid crystal layer in the light reflecting part is λ / 4. The reason is that light passes through the same passage.

Although there is a technique of partially changing the thickness of the liquid crystal cell to achieve this, this technique is not preferable because the manufacturing process is complicated. A possible solution to this is to use a polymer fixation method. Polymer fixation methods are characterized by making it possible to fix a particular state of orientation in an initial orientation. The use of this technique makes it possible to provide different amounts of retardation at the light transmissive and light reflective portions during switching, allowing the use of panels with constant cell thickness.

38 is a diagram showing a cross section of a horizontally oriented LCD according to the present embodiment, taken in a direction perpendicular to the substrate surface. FIG. 39 shows a view of the same state at a position corresponding to FIG. 38 as viewed from the normal line direction of the substrate. FIG. 38 and 39, the glass substrate 20 on the array substrate and the glass substrate 30 on the opposing substrate are provided in a facing relationship to seal the liquid crystal layer 24. A reflective electrode 72 having an uneven shape is locally formed on the glass substrate 20 on the array substrate. The region in which the reflective electrode 72 having the uneven shape is formed serves as the light reflecting portion 106, and the region in which the reflecting electrode 72 is not formed serves as the light transmitting portion 108. The λ / 4 plate 76 is attached to the surface of the glass substrate 20 opposite to the surface on which the reflective electrode 72 is formed between the polarizing plate 73 and the glass substrate 20, and the polarizing plate 73 is attached thereon. do. The polarizing plate 74 provided in the cross nicol relationship with the polarizing plate 73 is attached to the surface of the glass substrate 30 opposite to the liquid crystal layer 24. Although not shown, an alignment film is formed on the interface between the substrates 20 and 30 and the liquid crystal layer 24.

The process for the transmissive reflective LCD of the present embodiment using a polymer is described below. In the panel having the pixel electrode structures shown in FIGS. 38 and 39, the liquid crystal molecules 24a in the light transmitting portion 108 and the light reflecting portion 106 are formed so that the reflective electrode 72 extends (vertical direction in FIG. 39). It is horizontally oriented at a slight angle with respect to the direction. The liquid crystal molecules 24a have positive dielectric anisotropy (Δε). When a voltage is applied between the reflective electrodes 72, the liquid crystal molecules 24a in the gap between the electrodes (light transmitting portion 108) are rotated in a horizontal direction (direction parallel to the substrate surface) by almost 90 degrees. Switching action takes place. At this time, the retardation is changed approximately between -λ / 4 and λ / 4.

The initial orientation is fixed by irradiating the liquid crystal layer 24 with ultraviolet light from the side of the glass substrate 20 on the array substrate without applying a voltage to the liquid crystal layer 24. During this process, the monomers in the light transmissive portion 108 are first consumed to form a polymer on the interface of the substrate, and the monomers in the light reflective portion 106 that are shielded from light using the reflective electrode 72 remain. do. Next, ultraviolet light is irradiated to the liquid crystal layer 24 from the side of the glass substrate 30 on the counter substrate while a voltage is applied. As for the voltage application, appropriate conditions are selected to maximize the effect of the switching of the light reflection portion 106. In this case, since a large amount of unreacted monomer exists, polymerization proceeds sufficiently at the interface at the light reflection portion 106, while the monomer at the light transmission portion 108 is insufficient. Therefore, the orientation of the liquid crystal in the light transmitting portion 108 remains almost unchanged after the first step of ultraviolet light irradiation, so that the retardation is finally changed by 90 degrees rotation of the λ / 4 plate or by an amount substantially equal to λ / 2. Switching occurs. On the other hand, in the initial state of orientation, the direction of the liquid crystal molecules 24a in the light reflecting portion 106 may be rotated 45 degrees with respect to the liquid crystal molecules 24a in the light transmitting portion 108 because they may cause an optimum voltage. This is because it is fixed by using a polymer. This makes it possible to switch the liquid crystal molecules 24a in the light reflection portion 106 with a retardation change almost equal to the 45 degree rotation of the λ / 4 plate. Therefore, as described above, the transmissive reflective display device has a multi-gap structure (multi-gap structure) in the pixel by changing the optical switching capability (the amount of retardation change when the liquid crystal is switched) between the light reflection unit 106 and the light transmission unit 108. Switching can be effected even if no -gap structure is provided.

It will be readily understood that this same effect can be obtained by combining the liquid crystal having negative dielectric anisotropy and horizontal orientation with the above-described embodiment. In this case, the direction of the initial alignment process is 90 degrees different from the direction in the above-described embodiment, and is substantially perpendicular to the direction in which the electrode extends. In addition, unlike the above-described embodiment in which the reflective electrode 72 is used for light shielding, polymer fixation is applied to each area of the display using a light shielding such as a photo mask so that different switching capability is provided to the liquid crystal in each area. Different conditions may be applied.

Example 6-4

Fig. 40 is a view showing a cross section of a horizontally aligned transmissive reflective LCD according to Example 6-4, taken in a direction perpendicular to the substrate surface. FIG. 41 is a view of the same state at a position corresponding to FIG. 40 as seen from the normal direction of the substrate surface. FIG. 40 and 41, the glass substrate 20 on the array substrate and the glass substrate 30 on the opposing substrate face each other to seal the liquid crystal layer 24 having positive dielectric anisotropy. The reflective electrode 72 having an uneven shape is locally formed on the glass substrate 20 on the array substrate, and the transmissive electrode 104 is formed in a region where the reflective electrode 72 is not formed. The region where the reflective electrode 72 is formed serves as the light reflecting portion 106, and the region where the transmissive electrode 104 is formed serves as the light transmitting portion 108. The λ / 4 plate 76 and the polarizing plate 73 are attached to the surface of the glass substrate 20 opposite to the surface on which the reflective electrode 72 is formed in this order. The common electrode 26 is formed on the glass substrate 30 on the side where the liquid crystal layer 24 is present. The polarizing plate 74 in a parallel nicol relationship with the polarizing plate 73 is attached to the surface of the glass substrate 30 opposite to the liquid crystal layer 24. Although not shown, an alignment film is formed at the interface between the substrates 20 and 30 and the liquid crystal layer 24.

The polymer fixing process is the same as the process in Example 6-3. In the light transmissive portion 108, the liquid crystal molecules 24a oriented horizontally on the substrate surface are almost perpendicular to the substrate surface when a voltage is applied. At this time, the retardation is changed from lambda / 2 to 0 (if sufficient voltage is applied), and as a result, it is effectively switched to the transmission mode. In contrast, the liquid crystal molecules 24a in the light reflection portion 106 have an initial pretilt angle of about 45 degrees. Thus, they have a retardation of approximately [lambda] / 4, which is half of the light transmission portion 108 when viewed from the front. Thus, a retardation that changes from λ / 4 to zero can occur and as a result effective switching in the reflection mode can be achieved.

Thus, effective switching can be achieved in both the light transmitting portion 108 and the light reflecting portion 106. Polymer fixation techniques are used to make appropriate corrections of retardation in the light transmissive portion 108 or a portion of the light reflective portion 106 in a manner suitable for transmission or reflection. By carrying out the polymer fixing at the applied voltage, the retardation change in the switching time can be made small. As in Example 6-3, some of the conditions for fixing the polymer can be changed by applying or removing a voltage or by using a photo mask or the like.

Example 6-5

Hereinafter, an embodiment for preventing image sticking due to pretilt provided when using a polymer fixing technique will be described. As a result of the inventors' studies and experiments, some image sticking phenomena derived from the polymer fixation technique are different from those of the pre-tilt angle due to insufficient polymerization of the monomers, which is different from the conventionally observed image sticking due to electrical reasons. Caused by a variable. Thus, further improvements in polymer fixation techniques require more robust and more stable control of orientation.

First, one embodiment where conventional polymer fixing techniques are used in vertically oriented panels, in particular MVA-LCDs, is described. In the MVA-LCD, as is known in the art, an insulating structure or slit (obtained by patterning and removing a part of the pixel electrode) is formed on the TFT substrate, and in this regard, the insulating structure or slit (of the common electrode Obtained by patterning a part) is formed on the opposing substrate. The vertical alignment film is applied and formed on both substrates. This is a polyamic acid type alignment film.

A negative liquid crystal with negative dielectric anisotropy (Δε), for example, a material made by Merck KGaA (Δε: -3.8, NI-point: 70 degrees) was injected into an empty panel formed by bonding the substrates. Functional monomers for fixing polymers, optical initiators and the like were mixed in the negative liquid crystal at a ratio of several percent or less. The density of the functional monomer is its ratio to the liquid crystal system. The density of the optical initiator is its ratio with respect to the monomer. Both monomers with a liquid crystalline skeleton and non-liquid monomers may be used. Basically, any material which forms the nematic phase when mixed in the nematic liquid crystal may be used. In this case, a liquid crystal monoacrylate monomer (ULC-001-K1) manufactured by Dainippon Ink K.K was used as a typical material. The cell was prepared by irradiating the panel with 4 J / cm 2 ultraviolet light (from a high pressure mercury lamp) while applying a voltage of 5V.

The manufactured cell was provided with a polarizing plate, and its T-V characteristics were examined before and after the driving test performed by applying a voltage of 5 Vac for 24 hours to examine the change in the characteristics. Initial T-V characteristics (before the driving test) and T-V characteristics (after the driving test) were compared, and the change in transmittance in the stiff region of the T-V curve was expressed as a percentage. The same experiment was carried out on monomers having two or more functional groups and having the same basic structure and skeleton. Table 1 shows the results of the experiment.

Table 1

material Change in transmittance Monoacrylate 15% Diacrylate 6% Triacrylate 5%

As can be seen from Table 1, it is apparent that the polyfunctional monomers provide desirable results. This is possible because of the fact that polyfunctionality imparts some crosslinked structure to the resulting polymer. Table 2 shows the results of similar experiments performed by adding the crosslinking material.

Table 2

material Change in transmittance Monoacrylate 15% Monoacrylate with added crosslinking material 7%

Although the above description has been made with respect to acrylate monomers, this description is based on other monomers such as styrene, methacrylate, and acrylonitrile conjugated monomers and ethylene, vinyl acetate, vinyl chloride and other systems. The same applies to the non-conjugated monomer of.

The crosslinked structure is believed to play an important role in providing the so-called copolymers (copolymerized polymers) by mixing different monomers. For example, it is believed to be effective in mitigating the problem of each monomer in various properties such as solubility in host liquid crystals, electrical properties, and stability to image sticking. 42 is a diagram showing a cross section of the LCD according to the present embodiment, taken in a direction perpendicular to the substrate surface. As shown in FIG. 42, the liquid crystal layer 24 includes a copolymer layer 37 having a crosslinked structure in the vicinity of the substrates 20 and 30. 43 is a view schematically showing one of the structures of the copolymer. As shown in FIG. 43, a copolymer arranges two types of repeating units (CRU) (A and B) alternately, for example.

In addition, while the functional monomers have been described above, it is apparent that the polymer fixation can be performed using a mixture of oligomers and monomers. In this case, the oligomer may be polyester acrylate, polyurethane acrylate, epoxy acrylate, polyether acrylate, oligo acrylate, alkyd acrylate, polyol acrylate and the like. A degree of polymerization of 10 or less is preferred because it can provide sufficient solubility.

In summary, the present mode for the practice of the invention is uniform, in which polymer fixing is performed after a stable and uniform alignment of the liquid crystal by applying a voltage to the liquid crystal panel having a structure in which the alignment of the liquid crystal is likely to become unstable for a sufficient time. By giving a stable orientation it is possible to improve the IPS-LCD.

In the case of the reflective LCD, when the reflective electrode 72 having the concave-convex shape is formed, there is an effect that the surface unevenness is prevented from adversely affecting the orientation of the liquid crystal.

When evaluated as a base technology for polymer fixation for improved reliability, this mode for the practice of the invention is characterized in that a polymerized component is provided in the crosslinked structure to form a stable polymer on the interface of the substrate and a copolymer is provided.

As described above, in this mode for the practice of the invention, it is possible to make the alignment of the liquid crystal uniform and stable in the panel in which the alignment of the liquid crystal is not stable. This mode for the practice of the invention can also improve the reliability of the polymer fixed liquid crystal panel, and in particular, can sufficiently reduce image sticking.

[Seventh Mode for Implementation of the Invention]

Hereinafter, a liquid crystal display in the seventh mode for carrying out the invention will be described with reference to FIGS. 44A to 47B. The present mode for carrying out the invention uses a stripe-shaped electrode provided on the surface of the substrate to impart an operating component to the switching of the liquid crystal molecules in an azimuth angular direction.

TN mode liquid crystal displays have been widely used as active matrix type liquid crystal displays in which a liquid crystal material having positive dielectric anisotropy is oriented in a 90 degree twist between substrates in a parallel and facing relationship with the substrate surface. However, the TN mode liquid crystal display has a problem that the viewing angle characteristics are poor. Various studies have been made to improve the viewing angle characteristics under these circumstances.

Instead of the TN mode, the proposed method includes an in-plane switching (IPS) mode in which driving is performed by applying an electric field in the direction of the substrate surface (male direction). The mode of switching in the azimuth angle direction indicated by the IPS mode is much better than the mode of switching in the polar angle direction indicated by the TN mode in view of the viewing angle.

During this switching in the azimuth angle direction, it is important to prevent the azimuth angle of the director in the dark state from the initial state of orientation as a result of the driving of the liquid crystal molecules. However, even when the orientation is controlled using a rubbing process, the orientation direction has a time dependent shift with respect to the azimuth angle as driving continues when the rubbing intensity is weakened, resulting in a decrease in contrast. Occurs. When the orientation control is made with a non-contact substrate such as irradiating ultraviolet light in which fixation force (orientation adjustment force) can be provided smaller than when orientation control is possible using the rubbing process, the problem of shift in the orientation direction becomes more serious.

The objective in this mode for the practice of the invention is to suppress any time dependent shift in the alignment of the liquid crystal as a result of driving in a liquid crystal display device in which the switching of the liquid crystal in the azimuth angle direction comprises a factor, thereby providing high quality It is to provide a liquid crystal display device.

In the case of a liquid crystal display device in which the switching direction of the liquid crystal includes a factor in the azimuth angle direction indicated by the IPS mode display device governed by the component in the azimuth angle direction, the contrast is prevented from decreasing over time. In order to do this, it is required to prevent the orientation direction from changing from the initial state as a result of driving when the voltage is turned off (when a voltage less than the threshold voltage is applied). However, in addition to improving the rubbing force, it is not proposed to approach for the purpose of preventing the shift of the orientation.

As a result of the empirical study, it was found that the above object can be achieved by reacting and shaping an optically cured component that is almost oriented in the orientation adjustment direction in the azimuth angle direction of the alignment film (orientation control layer). 44 (a) and 44 (b) are diagrams showing the principle in this mode for carrying out the invention. FIG. 44A shows a state of a conventional liquid crystal display device in which time-dependent shifts occur in alignment of liquid crystals as a result of driving, and FIG. 44B shows time dependency in alignment of liquid crystals as a result of driving. It is a figure which shows the state of the liquid crystal display device in this mode for implementing the invention in which the shift is prevented. As shown in Fig. 44B, in the liquid crystal display device in the present mode for carrying out the invention, the optical curing component contained in the liquid crystal reacts with the liquid crystal molecules 24 oriented in the alignment adjustment direction of the alignment film to cure. do. This optical hardening component has the force which keeps the liquid crystal molecule 24 in an orientation state at the time of hardening. Thus, this optically cured component provides the orientation of the liquid crystal molecules 24 as indicated by arrow 101 in FIG. 44B in addition to the alignment adjustment provided by the alignment film as shown in FIG. 44B. Adjustment, which sufficiently alleviates the problem of time dependent shift in orientation as a result of driving.

The optical curing component may be cured by applying a voltage that is equal to or lower than the threshold voltage for transmission characteristics in a direction perpendicular to the substrate surface, or that changes only in the polar angle direction with little change in the azimuth angle direction. have. In other words, it is necessary to provide fixation energy at an azimuth angle equal to or greater than that provided by the alignment film in order to more strongly fix the orientation of the liquid crystal molecules at the interface. As shown in FIG. 45 (a), when the component is cured when switching is made by application of a voltage higher than the threshold value, the orientation adjusting force of the optical curable component is in the direction indicated by the arrow 102 in the figure. I remember. As a result, as shown in Fig. 45B, the alignment direction of the liquid crystal molecules in the dark state becomes unstable after driving for a long time, and pretilt occurs even when no voltage is applied. Therefore, the optical curing component may be formed to add the orientation adjusting force in the same direction (indicated by arrow 101) instead of the direction (indicated by arrow 102) different from the orientation adjustment direction of the alignment film. Even when the orientation in the pole angle direction changes slightly, there is almost no problem in contrast. In modes where there is a slight initial displacement of the orientation in the polar angle direction, a slight change in the polar angle may be fixed using an optical curing component, which not only fixes the orientation but also sufficiently improves the response speed. do.

Hereinafter, a liquid crystal display device in the present mode for carrying out the present invention will be described in detail with reference to embodiments.

Example 7-1

Embodiment 7-1 will be described with reference to FIGS. 46A and 46B. FIG. 46A is a diagram showing a part of pixels of the liquid crystal display according to the present embodiment, and FIG. 46B is a diagram showing a section taken along the line F-F in FIG. 46A. 46 (a) and 46 (b), the evaluation cell in the IPS mode has a glass substrate on the array substrate with a comb-shaped electrode 100 having a width of 5 μm and a gap width of 20 μm. It is formed on 20 and manufactured. The alignment film was formed by providing a polyimide material on a substrate based on spin coating. In order to provide five types of alignment adjustment force to the alignment film, rubbing was performed at three different intensities, and linearly polarized ultraviolet light was applied at two different intensities to provide two kinds of optical alignments. The direction of the orientation adjustment force in the azimuth angle was 10 degrees with respect to the longitudinal direction of the comb-tooth shaped electrode 100.

Table 3 shows the settling energy at the azimuth angle on the surface of the five types of alignment films described above, performed using the Neel Wall method, the initial contrast of the evaluation cell during the display of black, and the AC voltage for 72 hours at 35 ° C. The result of measuring the contrast of the evaluation cell during the display of the measured black after continuously displaying white in the cell at is shown.

Table 3

Settling energy from azimuth angle Initial contrast Contrast after 72 hours Loving 1 4.6 × 10 ^-5 330 320 Loving 2 3.1 × 10 ^-5 310 205 Loving 3 2.0 × 10 ^-5 285 140 Light orientation 1 5.4 × 10 ^-6 220 145 Light orientation 2 6.8 × 10 ^-7 200 130

As shown in Table 3, it was found that after a continuous display of white for 72 hours at an AC voltage at 35 ° C., the shift in the orientation direction is increased so that the contrast decreases and the fixation energy at the azimuth angle decreases. However, no significant change was observed in the cell with the largest fixation energy at the azimuth angle.

Table 4 shows the above-mentioned five kinds of cells for evaluation obtained by adding 0.3% by weight of bifunctional acrylate monomer manufactured by Merck KGaA and curing the injected monomer by irradiation with ultraviolet light without applying voltage. Improved results. As shown in Table 4, very effective and improved contrast was obtained in four kinds of cells in which the fixing energy was small as a result of the polymer fixing.

Table 4

Initial contrast Contrast after 72 hours without polymer fixation Contrast after 72 hours of polymer fixation Loving 2 310 205 290 Loving 3 285 140 280 Light orientation 1 220 145 220 Light orientation 2 200 130 195

Example 7-2

Embodiment 7-2 will be described with reference to FIGS. 47A and 47B. FIG. 47A shows a part of pixels of the liquid crystal display according to the present embodiment, and FIG. 47B shows a cross section taken along the line G-G of FIG. 47A. As shown in FIGS. 47A and 47B, the evaluation cell in the diagonal field switching mode has a comb-tooth shaped electrode having a width of 5 μm formed on the glass substrate 20 on the array substrate. 100 and a comb-tooth shaped electrode 101 having a width of 5 탆 formed on the glass substrate 30 on the counter electrode are alternately provided with a gap width of 20 탆 in a direction perpendicular to the substrate surface. do. The alignment film was formed by providing a polyimide material on a substrate based on spin coating.

In order to provide three types of alignment adjustment force to the alignment film, rubbing was performed at three different intensities as in Example 7-1, and the direction of the alignment adjustment force at the azimuth angle was determined by the longitudinal direction of the comb-shaped electrodes 100 and 101. It was a parallel direction.

Next, 0.3% by weight of bifunctional acrylate monomer made by Merck KGaA is added, and ultraviolet light is irradiated and cured while applying a voltage of 2.3 Vdc lower than a threshold voltage for achieving any transmission property thereto. As described above, the response speeds between the three types of evaluation cells and the cells to which no monomer was added were compared. Table 5 shows these results. The response speed of the cells to which the monomer was added increased. No decrease was observed in contrast or the like.

Table 5

Polymer fixed contrast Response rate (no polymer retention) Response rate (polymer locked) On off On off Loving 1 > 350 114 20 77 18 Loving 2 > 350 110 23 75 18 Loving 3 310 93 29 66 21

As described above, this mode for the practice of the invention makes it possible to suppress the time dependent shift in the alignment of the liquid crystal of the liquid crystal display as a result of the driving of the switching of the liquid crystal molecules comprising a factor in the azimuth angle direction. . When the present mode for carrying out the invention is applied to a mode in which switching of liquid crystal molecules includes a factor in a polar angle direction such as a liquid crystal mode driven by a diagonal field, an improvement in response speed is achieved and a high quality liquid crystal display An apparatus may be provided.

As described above, the present invention makes it possible to improve the light transmittance without lowering the response speed to tone change.

Claims (29)

A liquid crystal display device having an array substrate and an opposing substrate, which are coupled in a confronting relationship to seal a liquid crystal in contact with an alignment film or an electrode. And a polymer layer formed locally on the alignment film which determines the pretilt angle of the liquid crystal molecules of said liquid crystal and / or the tilt direction at the time of driving said liquid crystal. The method of claim 1, The polymer layer has a thickness in the range of 10 kV to 5,000 kV. The method of claim 1, And the orientation of the polymer in the polymer layer in contact with the liquid crystal on the top surface thereof is different from the orientation direction determined by the alignment film or electrode. The method of claim 3, wherein The polymer is a liquid crystal display, characterized in that the state and shape of the orientation in a plurality of regions different. The method of claim 3, wherein The polymer has an optical anisotropy, characterized in that the liquid crystal display device. In the liquid crystal material used for the liquid crystal display device, The molecular weight M _m of the monomer and the average molecular weight M _lc of the liquid crystal component excluding the monomer are M _m <M _lc A liquid crystal material characterized by satisfying a relational expression of × 1.5. The method of claim 6, M _m A liquid crystal material characterized by a relation represented by ≤ M _lc being further satisfied. The method of claim 6, Liquid crystal material, characterized in that the density of the monomer is in the range of 0.1 to 10% by weight. The method of claim 6, The monomer comprises a polymerization initiator having a molecular weight M _ini , M _ini A related formula represented by ≤ M _lc is satisfied. The method of claim 9, The density of the polymerization initiator in the photomonomer is in the range of 0.1 to 10% by weight. The method of claim 6, The molecular weight of the said monomer is 400 or less, The liquid crystal material characterized by the above-mentioned. A liquid crystal display device comprising two substrates coupled in a facing relationship and sealing a liquid crystal layer therebetween, The said liquid crystal layer contains the liquid crystal material of any one of Claims 6-11, The liquid crystal display device characterized by the above-mentioned. A liquid crystal arranged almost horizontally above a substrate surface, and having a transverse electric field applied substantially parallel to said substrate surface, and In-plane switching, characterized in that it comprises a polymer layer for fixing the orientation of the liquid crystal formed by polymerizing the optically or thermally polymerized polymerization component contained in the liquid crystal while applying a voltage to the liquid crystal. Type liquid crystal display device. A liquid crystal containing a polymerization component which is sealed between a pair of substrates installed in a facing relationship and which is optically or thermally polymerized, A reflective electrode installed on one of the substrates, and And a polymer layer for fixing the orientation of the liquid crystal formed on the reflective electrode by polymerizing the polymerization component while applying a voltage to the liquid crystal. A liquid crystal containing a polymerization component that is sealed between a pair of substrates provided in a facing relationship and that is optically or thermally polymerized, A light reflection portion and a light transmission portion installed on a surface of one of the substrates, and And a polymer layer for fixing the alignment of the liquid crystal formed on the light reflection portion and the light transmission portion by polymerizing the polymerization component while adjusting the voltage applied to the liquid crystal. The method of claim 15, When the voltage is applied to the liquid crystal, the liquid crystal molecules on the light reflection portion are rotated by approximately 45 degrees in a plane substantially parallel to the surface of the substrate to become a retardation change amount of λ / 4, and the liquid crystal molecules on the light transmission portion are When a voltage is applied to the liquid crystal, a transmissive reflection liquid crystal display device which is rotated by approximately 90 degrees in a plane substantially parallel to the surface of the substrate to be a retardation change amount of λ / 2. The method of claim 15, When a voltage is applied to the liquid crystal, the liquid crystal molecules on the light reflecting portion rotate about 45 degrees to a plane substantially perpendicular to the surface of the substrate to become a retardation change amount of λ / 4, and the liquid crystal molecules on the light transmitting portion are When a voltage is applied to the liquid crystal, the transmission reflection liquid crystal display device, characterized in that the retardation change amount of λ / 2 is rotated by approximately 90 degrees in a plane substantially perpendicular to the surface of the substrate. The method of claim 16, And the polymer layer determines an initial state of alignment of liquid crystal molecules on the light reflecting portion and the light transmitting portion. The method of claim 17, And the polymer layer determines an initial state of alignment of liquid crystal molecules on the light reflecting portion and the light transmitting portion. A polymer layer for fixing the orientation of the liquid crystal formed on the surface of the substrate by polymerizing an optically polymerized photopolymerization component contained in the liquid crystal while applying a voltage to the liquid crystal, and A liquid crystal display device comprising two or more types of photopolymerization monomers contained in a photopolymerization component which is polymerized on the basis of copolymerization. A liquid crystal display device comprising a polymer layer for fixing an orientation of the liquid crystal formed on the surface of a substrate by polymerizing an optically polymerized photopolymerization component contained in the liquid crystal while applying a voltage to the liquid crystal. The photopolymerization component is not only polymerized but also crosslinked. A pair of substrates installed in a face to face relationship, An alignment film formed on each surface of the substrate in a facing relationship, A liquid crystal layer containing an optical curing component and a nematic liquid crystal cured to almost align the orientation direction at the azimuth angle of the liquid crystal molecules with the direction at the azimuth angle of orientation control performed by the alignment film, and And an electrode structure for generating an electric field having a component parallel to the surface of the substrate in the liquid crystal layer. The method of claim 22, A fixing energy in the azimuth angle direction acting on the liquid crystal molecules on the surface of the alignment film is 3 x 10 ^-5 J / m 2 or less.  The method of claim 22, A structure having a concave-convex shape on the surface of the alignment film is used as a factor for determining the alignment of the liquid crystal molecules. An array substrate and an opposite substrate, which are coupled in a face to face relationship to seal the liquid crystal, An alignment film on which the photo alignment process is performed, and And a polymer layer formed on the alignment film which determines the pretilt angle of the liquid crystal molecules of said liquid crystal and / or the tilt direction at the time of driving said liquid crystal. The method of claim 25, The polymer layer has a thickness in the range of 10 kV to 5000 kV. The method of claim 25, And the orientation of the polymer in the polymer layer in contact with the liquid crystal on the top surface thereof is different from the orientation direction determined by the alignment film or electrode. The method of claim 27, The polymer is a liquid crystal display, characterized in that the state and shape of the orientation in a plurality of regions different. The method of claim 27, The polymer has an optical anisotropy, characterized in that the liquid crystal display device.

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