HK1115451B - In plane, switching type liquid crystal display device - Google Patents

Description

Liquid crystal display element of transverse electric field control type

Technical Field

The present invention relates to a liquid crystal display element in which the orientation of liquid crystal molecules is controlled by a transverse electric field having a direction parallel to a substrate.

Background

As a liquid crystal display element, a lateral electric field control type liquid crystal display element is known in which the orientation of liquid crystal molecules is controlled by a lateral electric field in a direction parallel to a substrate constituting the liquid crystal display element.

The liquid crystal display element includes: a pair of substrates disposed opposite to each other with a predetermined gap therebetween, and having opposing inner surfaces on which alignment processes are performed in parallel and in opposite directions; and a liquid crystal layer in which liquid crystal molecules are aligned so that the long axes of the liquid crystal molecules are aligned substantially parallel to the substrate surfaces, and the liquid crystal is sealed in a gap between the substrates. On the inner surface of one of the pair of substrates, a plurality of elongated electrode portions are provided at intervals in a predetermined region for forming 1 pixel, and pixel electrodes are formed in parallel. Further, a counter electrode is provided on the one substrate, the counter electrode and the pixel electrode are insulated from each other, and a voltage is applied between the counter electrode and the pixel electrode to generate a transverse electric field in which a molecular long axis direction of the liquid crystal molecules changes in a direction substantially parallel to the substrate surface between the counter electrode and the plurality of electrode portions of the pixel electrode.

In the transverse electric field control type liquid crystal display element, a transverse electric field corresponding to display data is generated between the pixel electrode and the counter electrode, and the molecular long axis direction of liquid crystal molecules is controlled in a plane substantially parallel to the substrate surface in each of a plurality of pixels formed in a region corresponding to the pixel electrode and the counter electrode, thereby displaying an image.

However, in the lateral electric field control type liquid crystal display element, as described in japanese patent application laid-open No. 2002-182230, in order to improve the viewing angle dependence of display and perform wide viewing angle display, it is proposed to form a plurality of electrode portions of the pixel electrode in a "<" -shaped curved shape. That is, since the direction of the lateral electric field generated between one electrode and the opposite electrode and the direction of the lateral electric field generated between the other electrode and the opposite electrode are different from each other in the two portions sandwiching the "<" -shaped bent portion, the pixel electrode is formed such that the liquid crystal molecules are aligned in two different directions in each pixel.

However, in the liquid crystal display element of the transverse electric field control type in which the plurality of electrode portions of the pixel electrode are formed in the "<" -shaped curved shape, when a strong transverse electric field is generated, the alignment state of liquid crystal molecules is not uniform in each pixel, and there is a problem that display unevenness is caused by the pixels.

Disclosure of Invention

The invention provides a lateral electric field control type liquid crystal display element which has a wide visual field, no display unevenness and good display quality.

In order to achieve the above object, a liquid crystal display element according to the present invention includes: the substrate processing apparatus includes a pair of substrates arranged opposite to each other with a predetermined gap therebetween, and subjected to alignment processing in directions parallel to each other on inner surfaces facing each other; a liquid crystal layer sealed in a gap between the pair of substrates, having long molecular axes of liquid crystal molecules aligned in the alignment direction, and aligned substantially parallel to the substrate surfaces; a plurality of 1 st electrodes provided on an inner surface of one of the opposed inner surfaces of the pair of substrates, the plurality of 1 st electrodes including: one and the other straight line portions extending in directions intersecting at respectively different angles with respect to the direction of the above-described alignment treatment in each predetermined region for forming 1 pixel; curved portions provided at mutually adjacent ends of the one and the other linear portions, respectively, and extending in a direction intersecting the direction of the orientation treatment at an angle larger than an intersection angle of the one and the other linear portions with the direction of the orientation treatment, respectively; and a connecting portion connecting the bent portions; and a 2 nd electrode which is arranged on the inner surface of the one substrate so as to be insulated from the 1 st electrode, and which generates a transverse electric field between the 2 nd electrode and the 1 st electrode for changing the direction of the long molecular axis of the liquid crystal molecules in a plane substantially parallel to the substrate surface, wherein when an inclination angle of one and the other linear portions of the 1 st electrode with respect to an alignment treatment direction is represented as θ a, and an inclination angle of each of the bent portions provided at the end portions of the 2 adjacent linear portions with respect to the alignment treatment direction is represented as θ b, the inclination angles are set to 0 ° < θ a < 20 °, 20 ° < θ b < 40 °, the lengths of the one and the other linear portions of the 1 st electrode are La, and the lengths of the bent portions are set to La > nLb and 10Lb > La > 4Lb, n: 3 to 5.

The liquid crystal display element of the present invention can provide a wide viewing field and good display quality without display unevenness.

Drawings

Fig. 1 is a plan view showing a part of one substrate of a liquid crystal display element according to an embodiment of the present invention.

Fig. 2 is a sectional view of the liquid crystal display element shown in fig. 1 taken along line II-II.

Fig. 3 is an enlarged plan view showing a part of the pixel electrode and the counter electrode of the liquid crystal display element shown in fig. 1 in an enlarged manner.

Fig. 4 is an enlarged plan view showing one bent electrode of the pixel electrode of the liquid crystal display element shown in fig. 1 in an enlarged manner.

Fig. 5 is an enlarged sectional view showing an enlarged cross section of the liquid crystal display element shown in fig. 1 taken along the line V-V of fig. 3.

Fig. 6 is a plan view showing the arrangement state of liquid crystal molecules in each portion of 1 pixel when a lateral electric field is generated between the pixel electrode and the counter electrode.

Fig. 7 is an enlarged sectional view showing a section after the liquid crystal display element shown in fig. 1 is cut along line VII-VII of fig. 6 in an enlarged manner.

Fig. 8 is an enlarged sectional view showing an enlarged cross section of the liquid crystal display element shown in fig. 1 taken along line VIII-VIII of fig. 6.

Fig. 9 is a plan view showing an alignment state of liquid crystal molecules in each portion of 1 pixel when a lateral electric field is generated between a pixel electrode and a counter electrode, in a comparative example in which a plurality of bent electrodes of the pixel electrode are formed in a "<" shape directly connecting 2 electrodes.

Fig. 10 is an enlarged cross-sectional view showing an enlarged cross-section taken along the X-X line of fig. 9 in the comparative example shown in fig. 9.

Fig. 11 is an enlarged cross-sectional view showing a cross-section taken along line XI-XI of fig. 9 in the comparative example shown in fig. 9 in an enlarged manner.

Detailed Description

Fig. 1 to 8 show an embodiment of the present invention, fig. 1 is a plan view showing a part of one substrate of a liquid crystal display element, and fig. 2 is a sectional view showing the liquid crystal display element shown in fig. 1 taken along line II-II.

As shown in fig. 1 and 2, the liquid crystal display element includes a pair of transparent substrates 1 and 2 disposed opposite to each other on an observation side (upper side in fig. 2) with a predetermined gap therebetween, and a liquid crystal layer 3 sealed in the gap between the pair of substrates 1 and 2. On one of the inner surfaces of the pair of substrates 1 and 2 facing each other, for example, on the inner surface of the substrate 2 on the opposite side to the observation side, the 1 st and 2 nd transparent electrodes 4 and 5 for generating a transverse electric field substantially parallel to the plate surfaces of the substrates 1 and 2 by applying a voltage are provided so as to be insulated from each other. 1 of the plurality of 1 st transparent electrodes 4 faces the 2 nd transparent electrode 5, and 1 pixel 100 for controlling the molecular long axis direction of the liquid crystal molecules of the liquid crystal layer 3 is defined by a region between which the lateral electric field is generated. A plurality of these pixels are arranged in a matrix. A pair of polarizing plates 19 and 20 on the observation side and the opposite side are disposed on the outer surfaces of the pair of substrates 1 and 2, respectively.

Hereinafter, the substrate 1 on the observation side is referred to as a front substrate, the substrate 2 on the opposite side to the observation side is referred to as a rear substrate, the polarizing plate 19 on the observation side disposed on the outer surface of the front substrate 1 is referred to as a front polarizing plate, and the polarizing plate 20 on the opposite side to the outer surface of the rear substrate 2 is referred to as a rear polarizing plate.

The pair of substrates 1 and 2 are bonded to each other by a frame-shaped plate member, not shown, and the liquid crystal layer 3 is sealed in a region surrounded by the plate member in a gap between the pair of substrates 1 and 2.

The liquid crystal display element is an active matrix liquid crystal display element, and among the 1 st and 2 nd electrodes 4 and 5 provided on the inner surface of the rear substrate 2 so as to be insulated from each other, the 1 st electrode 4 is a plurality of pixel electrodes arranged in a matrix in the row direction (left-right direction of the screen) and the column direction (up-down direction of the screen), and the 2 nd electrode 5 is a counter electrode provided for each of the rows in correspondence with each of the pixel electrodes 4 of the row.

On the inner surface of the rear substrate 2, provided are: a plurality of active elements 6 provided corresponding to the plurality of pixels 100, respectively; a plurality of scanning lines 12 provided for each of pixel rows formed by the plurality of pixels 100 arranged in the row direction; and a plurality of signal lines 13 provided for each of the pixel columns of the plurality of pixels 100 arranged in the column direction.

The active element 6 includes an input electrode 10 and an output electrode 11 for signals, and a control electrode 7 for controlling conduction between the input electrode 10 and the output electrode 11, the control electrode 7 is connected to a scanning line 12 in each row, the input electrode 10 is connected to a signal line 13 in each column, and the output electrode 11 is connected to the pixel electrode 4.

The active element 6 is, for example, a thin film transistor (hereinafter, referred to as a TFT 6). A gate electrode (control electrode) 7 formed on the substrate surface of the rear substrate 2; a transparent gate insulating film 8 formed on substantially the entire surface of the rear substrate 2 so as to cover the gate electrode 7; an i-type semiconductor film 9 formed on the gate insulating film 8 so as to face the gate electrode 7; a drain electrode (input electrode) 10 and a source electrode (output electrode) 11 provided through an n-type semiconductor film (not shown) on both sides of the above-described i-type semiconductor film 9.

The plurality of scanning lines 12 are formed on the substrate surface of the rear substrate 2 along one side (lower side in fig. 1) of each pixel row in parallel with the pixel row, and are connected to the gate electrodes 7 of the TFTs 6 in each row. The plurality of signal lines 13 are formed on the gate insulating film 8 along one side (left side in fig. 1) of each pixel column in parallel with the pixel column, and are connected to the drain electrodes 10 of the TFTs 6 of each column.

A terminal array portion (not shown) protruding toward the outer surface of the front substrate 1 is formed at the edge of the rear substrate 2, and the plurality of scanning lines 12 and the plurality of signal lines 13 are connected to a plurality of scanning line terminals and a plurality of signal line terminals provided at the terminal array portion.

The plurality of pixel electrodes 4 are formed on the transparent interlayer insulating film 14 formed on substantially the entire surface of the rear substrate 2 so as to cover the plurality of TFTs 6 and the signal lines 13. The counter electrode 5 is formed on the gate insulating film 8. That is, the counter electrode 5 is formed on the rear substrate 2 side of the plurality of pixel electrodes 4, and is insulated from the plurality of pixel electrodes 4 by the interlayer insulating film 14.

The pixel electrodes 4 are formed in an elongated shape having a length substantially extending over the entire longitudinal width direction of a region, which is a predetermined region for forming 1 pixel 100, for example, a rectangular region having a longitudinal width in the vertical direction of the screen formed in a longitudinal direction larger than a lateral width in the horizontal direction of the screen, by a plurality of elongated bent electrodes 41 through a 1 st transparent conductive film (for example, an ITO film) 40 formed in parallel.

The plurality of bent electrodes 41 of the pixel electrode 4 are formed by providing a plurality of slits in the 1 st conductive film 40, and the bent electrodes 41 are connected at both ends to the common connection portions 45a and 45b formed at both ends of the 1 st conductive film 40, respectively.

One end side of the common connection portion 45b at one end (lower end in fig. 1) of the 1 st conductive film 40 is overlapped on the source electrode 11 of the TFT6 via the interlayer insulating film 14, and is connected to the source electrode 11 through a contact (contact) hole (not shown) provided in the interlayer insulating film 14.

The counter electrode 5 is formed of a 2 nd transparent conductive film (e.g., an ITO film) 50 formed in a shape corresponding to the entire area of the plurality of pixels 100 in each row, and provided over the entire length of each pixel row.

As shown in fig. 1, the 2 nd conductive film 50 is patterned on an elongated rectangular opposing portion 51 corresponding to the shape of the plurality of pixels 100 in each row, and is formed in a shape in which the opposing portion 51 is connected to an end portion on the opposite side of one side of the scanning line 12 (an upper end of the pixel 100 in the figure) via a common connection portion 52.

The 2 nd conductive film 50 may be formed to have a width corresponding to the vertical width of the pixel 100 over the entire length of the pixel row. In this case, the 2 nd conductive film 50 is formed so as to cross the plurality of signal lines 13, and the intersection between the conductive film 50 and the signal line 13 is insulated by an insulating film, not shown, provided so as to cover the signal line 13.

The plurality of 2 nd conductive films 50 corresponding to the respective pixel rows are commonly connected (not shown) outside the display region where the plurality of pixel electrodes 4 are arranged, and the common connection portion is connected to a counter electrode terminal provided in the terminal arrangement portion of the rear substrate 2.

By applying a voltage between the counter electrode 5 and the pixel electrode 4, a transverse electric field is generated between the counter electrode 5 formed of the 2 nd conductive film 50 and the plurality of bent electrodes 41 of the pixel electrode 4, the direction of the molecular long axis of the liquid crystal molecules 3a being changed in a plane substantially parallel to the surfaces of the substrates 1 and 2.

On the other hand, a light shielding film 15 is formed on the inner surface of the front substrate 1 so as to correspond to the regions between the plurality of pixels 100 and the plurality of TFTs 6, and color filters 16R, 16G, and 16B of three colors of red, green, and blue are provided on the light shielding film so as to correspond to the plurality of pixels 100, respectively.

Horizontal alignment films 17 and 18 such as polyimide films are formed on the inner surfaces of the pair of substrates 1 and 2 so as to cover the color filters 16R, 16G, and 16B provided on the front substrate 1 and the plurality of pixel electrodes 4 provided on the rear substrate 2, respectively, and to align the liquid crystal molecules 3a of the liquid crystal layer 3 substantially parallel to the surfaces of the substrates 1 and 2 by rotating the long axes of the molecules.

Then, the film surfaces of the alignment films 17 and 18 are rubbed in a predetermined direction, whereby the alignment treatment is performed on the inner surfaces of the pair of substrates 1 and 2 in parallel and in the opposite direction to each other.

Fig. 3 is an enlarged plan view showing a part of the pixel electrode 4 and the counter electrode 5 in an enlarged manner. Fig. 4 is an enlarged plan view showing one bent electrode 41 of the pixel electrode 4 in an enlarged manner.

In fig. 1, 3, and 4, 1a indicates the orientation treatment direction (rubbing direction of the orientation film 17) of the inner surface of the front substrate 1, and 2a indicates the orientation treatment direction (rubbing direction of the orientation film 18) of the inner surface of the rear substrate 2. In the present embodiment, the alignment process is performed on the horizontal alignment film 17 on the inner surface of the front substrate 1 from below to above in parallel with the vertical direction of the screen, and the alignment process is performed on the horizontal alignment film 18 on the inner surface of the rear substrate 2 from above to below in parallel with the vertical direction of the screen.

As shown in fig. 3 and 4, the 2 straight portions 42a and 42b of the plurality of bent electrodes 41 of the pixel electrode 4 are formed to intersect at different angles with respect to the alignment treatment directions 1a and 2a, respectively, and the 2 straight portions 42a and 42b are bent in a "<" shape in which the portions intersecting with each other are connected at the center in the longitudinal direction of the rectangular pixel region. A bent portion 43a is provided at a portion connecting the 2 linear portions 42a, 42b, and a side connecting one linear portion 42a is bent in a direction in which an inclination angle with respect to the orientation processing direction 1a, 2a becomes larger with respect to the linear portion 42 a; the bent portion 43b is bent in a direction in which the inclination angle with respect to the alignment treatment direction 1a, 2a increases with respect to the other linear portion 42b on the side connected to the other linear portion 42 b. The connecting portions connecting the bent portions 43a and 43b connected to the 2 linear portions 42a and 42b are formed in an arc shape in which both side edges of one and the other are smoothly connected to each other.

In other words, the bent electrode 41 is formed continuously by 2 straight portions 42a and 42b having 1 st inclination angles different in inclination direction with respect to the alignment treatment directions 1a and 2 a; bent portions 43a, 43b having a 2 nd inclination angle which is larger than the 1 st inclination angle and different in inclination angle direction with respect to the orientation processing directions 1a, 2 a; and a connecting portion connecting these bent portions 43a and 43b to each other.

The 2 linear portions 42a and 42b of the bent electrode 41 are formed to have substantially the same width. Width W of one linear portion 42a₁And a ratio D of the distance D1 between the one linear portion 42a and 42a of the adjacent bent electrode 41₁/W₁And the width W of the other linear portion 42b₂And the other linear portions 42b and 42b of the adjacent curved electrodes 41 at intervals D₂Ratio D of₂/W₂Are set to 1/3-3/1, preferably 1/1.

In addition, regarding the inclination angles of the 2 linear portions 42a and 42b of the plurality of bent electrodes 41 of the pixel electrode 4 with respect to the alignment processing directions 1a and 2a and the inclination angles of the 2 bent portions 43a and 43b connecting the 2 linear portions 42a and 42b with respect to the alignment processing directions 1a and 2a, when the inclination angles of the linear portions 42a and 42b are θ a and the inclination angles of the bent portions 43a and 43b are θ b, the following are respectively set:

0°＜θa＜20°

20°＜θb＜40°。

further, the length of the 2 linear portions 42a and 42b and the length of the "<" -shaped 2 curved portions 43a and 43b connecting the 2 linear portions 42a and 42b are respectively set to La and Lb, respectively, when the length of the linear portions 42a and 42b is La and the length of the curved portions 43a and 43b is Lb:

La＞nLb(n：3～5)

10Lb＞La＞4Lb。

in addition, end bent portions 44a and 44b are formed at opposite ends of the mutually connected ends of the 2 linear portions 42a and 42b of the plurality of bent electrodes 41 of the pixel electrode 4, respectively, and the bent portions 44a and 44b are connected to the linear portions 42a and 42b and bent in directions in which the inclination angles with respect to the alignment treatment directions 1a and 2a become larger with respect to the linear portions 42a and 42 b. The connecting portions between the end bent portions 44a and 44b and the linear portions 42a and 42b are formed in the shape of circular arcs in which both side edges of one and the other are smoothly connected to each other.

The inclination angles of the end bent portions 44a, 44b formed at the ends of the 2 linear portions 42a, 42b with respect to the orientation processing directions 1a, 2a are set to be, when the inclination angles are represented as θ c:

20°＜θc＜40°

when the length of the end bent portions 44a and 44b is denoted as Lc, the length La of the linear portions 42a and 42b of the bent electrode 41 is set as follows:

La＞nLc(n：3～5)

10Lc＞La＞4Lc

in other words, the end bent portions 44a and 44b at both ends of the bent electrode 41 are formed to have substantially the same inclination and length as the bent portions 43a and 43b connecting the 2 linear portions 42a and 42 b.

The inclination angle θ a of the 2 linear portions 42a and 42b of the plurality of bent electrodes 41 of the pixel electrode 4 with respect to the alignment treatment directions 1a and 2a is preferably 10 ° ± 5 °, and more preferably 10 ° ± 2 °. The inclination angles θ b and θ c of the bent portions 43a and 43b and the end bent portions 44a and 44b connecting the 2 linear portions 42a and 42b with respect to the orientation processing directions 1a and 2a are preferably set to 30 ° ± 5 °, and more preferably 30 ° ± 2 °.

Among the plurality of bent electrodes 41 of the pixel electrode 4, the linear portion 42b connected to the TFT6 is formed to have a length shorter than that of the other linear portion 42b, avoiding the region corresponding to the source electrode 11 of the TFT 6.

The liquid crystal layer 3 is composed of nematic liquid crystal having positive dielectric anisotropy, and in an initial state where no electric field is generated between the pixel electrode 4 and the counter electrode 5, the liquid crystal layer 3 has a molecular long axis of the liquid crystal molecules 3a aligned in the alignment treatment directions 1a and 2a and aligned substantially parallel to the surfaces of the substrates 1 and 2.

Fig. 5 shows an enlarged cross section after cutting along the line V-V of fig. 3. As shown in fig. 3 and 5, the liquid crystal molecules 3a are aligned in the pre-tilt state such that the long axes thereof are aligned with the alignment treatment directions 1a and 2a, and the ends of the liquid crystal molecules formed on the inner surfaces of the respective substrates on the alignment treatment directions 1a and 2a side are spaced apart from the respective substrates. In other words, the liquid crystal molecules 3a are aligned substantially parallel to the surfaces of the substrates 1 and 2.

Further, a film-like transparent static-electricity-blocking conductive film 21 for blocking external static electricity is provided on the entire surface of the front substrate 1 between the front substrate 1 and a front polarizing plate 19 provided on the outer surface thereof.

In this liquid crystal display element, a drive voltage corresponding to display data is applied between the pixel electrode 4 and the counter electrode 5 of the plurality of pixels 100, a transverse electric field substantially parallel to the surfaces of the front substrates 1 and 2 is generated between the plurality of bend electrodes 41 of the pixel electrode 4 and the counter electrode 5 along the direction of the molecular long axis of the liquid crystal molecules 3a, and the direction of the molecular long axis of the liquid crystal molecules 3a of the plurality of pixels 100 is controlled in a plane substantially parallel to the surfaces of the front substrates 1 and 2 by the transverse electric field, thereby displaying an image.

The driving voltage applied between the pixel electrode 4 and the counter electrode 5 is controlled in accordance with display data so as to be in a range from a minimum value of substantially 0V, which does not generate a lateral electric field, to a maximum value generating a strong lateral electric field for aligning the liquid crystal molecules 3a in the pixel region where the pixel electrode 4 is provided in a direction in which the molecular long axis is rotated by 45 ° with respect to the alignment treatment directions 1a and 2 a.

The liquid crystal display element of the present embodiment is of an electric field-free black display type (hereinafter referred to as a normally black type), in which, for example, the light transmission axis of one of the front polarizing plate 19 and the rear polarizing plate 20 is made substantially parallel to or substantially perpendicular to the alignment treatment directions 1a and 2a, and the light transmission axis of the other polarizing plate is made substantially perpendicular to the light transmission axis of the one polarizing plate. When no electric field in which a transverse electric field is generated between the pixel electrode 4 and the counter electrode 5, that is, when the long molecular axes of the liquid crystal molecules 3a are aligned in the same direction as the alignment treatment directions 1a and 2a as shown in fig. 3, the pixel 100 displays black. When a strong electric field is generated between the pixel electrode 4 and the counter electrode 5, in which the long axes of the liquid crystal molecules 3a are aligned in a direction rotated by 45 ° with respect to the alignment treatment directions 1a and 2a, the pixel 100 displays brightest light.

Fig. 6 shows the molecular long axis direction of each part of the liquid crystal molecules 3a in 1 pixel 100 when a strong electric field is generated between the pixel electrode 4 and the counter electrode 5, the strong electric field aligning the molecular long axes of the liquid crystal molecules 3a in a direction rotated by 45 ° with respect to the alignment treatment directions 1a and 2 a. Fig. 7 is an enlarged view showing a cross section taken along line VII-VII of fig. 6. Fig. 8 is an enlarged view showing a cross section taken along line VIII-VIII of fig. 6.

As shown in fig. 6 and 8, a lateral electric field E is generated between one side edge (fringe) and the other side edge of the plurality of curved electrodes 41 of the pixel electrode 4 and a portion adjacent to the curved electrode 41 of the counter electrode 5.

The lateral electric field E is an electric field in a direction perpendicular to the side edges of the plurality of bent electrodes 41 of the pixel electrode 4, and the direction of the liquid crystal molecules 3a is changed in a direction in which the angle of the molecular long axis with respect to the direction of the lateral electric field E is decreased by generating the lateral electric field E.

In this liquid crystal display element, the plurality of bent electrodes 41 of the pixel electrode 4 are bent into a "<" shape, and 2 linear portions 42a and 42b intersect with each other at substantially the same angle with respect to the alignment treatment directions 1a and 2a of the inner surfaces of the pair of substrates 1 and 2. Therefore, as shown in fig. 6, the direction of the lateral electric field E generated between one straight portion 42a of the plurality of curved electrodes 41 of the pixel electrode 4 and the counter electrode 5, and the direction of the lateral electric field E generated between the other straight portion 42b of the curved electrode 41 and the counter electrode 5 may be different from each other. Therefore, in each pixel 100, a region in which the liquid crystal molecules 3a are aligned in 2 different directions can be formed, and wide viewing angle display with small viewing angle dependence of display can be performed.

A bent portion 43a is provided in a portion connecting 2 linear portions 42a and 42b of the plurality of bent electrodes 41 of the pixel electrode 4, and a side connecting one linear portion 42a is bent in a direction in which an inclination angle with respect to the alignment processing direction 1a and 2a becomes larger with respect to the linear portion 42 a; the bent portion 43b is formed in a shape in which one side connected to the other linear portion 42b is bent in a direction in which an inclination angle with respect to the alignment treatment direction 1a or 2a becomes larger with respect to the other linear portion 42b, and these bent portions 43a and 43b are connected to each other at a connecting portion. Therefore, even when a strong lateral electric field E is generated between the pixel electrode 4 and the counter electrode 5 so that the liquid crystal molecules 3a are aligned substantially at 45 ° or in the vicinity thereof with respect to the alignment treatment directions 1a and 2a toward the molecular long axis, the liquid crystal molecules 3a are not tilted at a tilt angle opposite to the tilt angle of the pre-tilt by the alignment treatment.

In other words, as shown in the comparative example of fig. 9, in the "<" -shaped electrode, the lateral electric field E generated between one side edge of the linear portion 42a or 42b and the counter electrode 5 and the lateral electric field E generated between the other side edge of the linear portion 42a or 42b and the counter electrode 5 are opposite to each other. The plurality of bent electrodes 41 of the pixel electrode 4 are bent into a substantially "<" shape, and the 2 linear portions 42a and 42b are formed so as to intersect with each other at opposite inclinations with respect to the alignment treatment directions 1a and 2 a.

The lateral electric field E generated between one side edge of one linear portion 42a of the curved electrode 41 of the pixel electrode 4 and the counter electrode 5 and the lateral electric field E generated between the other side edge of the other linear portion 42b of the curved electrode 41 and the counter electrode 5 are electric fields in directions in which the liquid crystal molecules 3a whose directions are changed by the lateral electric field E are inclined at an inclination angle opposite to the inclination angle of the pretilt caused by the alignment treatment of the inner surface of the substrate (hereinafter, referred to as reverse electric fields).

Therefore, when a strong lateral electric field E is generated between the pixel electrode 4 and the counter electrode 5, the force with which the liquid crystal molecules 3a are tilted by the lateral electric field E acting on the liquid crystal molecules 3a is stronger than the force with which the liquid crystal molecules 3a are pretilted by the alignment treatment of the substrate inner surface (the tilt alignment force of the alignment films 17 and 18), and the liquid crystal molecules 3a in the reverse electric field generation region S1 along one side edge of the one linear portion 42a of the curved electrode 41 and the liquid crystal molecules 3a in the reverse electric field generation region S2 along the other side edge of the other linear portion 42b are tilted at a tilt angle opposite to the tilt angle of the pretilt by the alignment treatment of the substrate inner surface.

In other words, when the lateral electric field E is a weak electric field in which the molecular long axis direction of the liquid crystal molecules 3a changes at a small angle with respect to the alignment treatment directions 1a and 2a, the liquid crystal molecules 3a change direction in the reverse electric field generation region in a state in which they are tilted in the tilt angle direction of the pretilt by the alignment treatment of the substrate inner surface due to the pretilt alignment force of the substrate inner surface. However, when the lateral electric field E is a strong electric field in which the longitudinal direction of the liquid crystal molecules 3a changes at a large angle with respect to the alignment treatment directions 1a and 2a, the force due to the lateral electric field E acts more strongly on the liquid crystal molecules 3a than the pre-tilt alignment force of the inner surface of the substrate, and the liquid crystal molecules 3a in the reverse electric field generation regions S1 and S2 are tilted at a tilt angle opposite to the tilt angle of the pre-tilt due to the alignment treatment.

The reverse tilt of the liquid crystal molecules 3a by the transverse electric field E (tilt of a tilt angle opposite to the tilt angle of the pre-tilt by the alignment treatment of the inner surface of the substrate) appears from the portion corresponding to the "<" -shaped bend, and as the transverse electric field E becomes stronger, the reverse tilt region becomes longer and larger along the 2 linear portions 42a and 42 b.

Fig. 9 shows a cross section taken along the X-X line of fig. 9, and fig. 11 shows a cross section taken along the XI-XI line of fig. 9, in a comparative example in which the plurality of curved electrodes 41 of the pixel electrode 4 are formed in a "<" shape in which the 2 linear portions 42a, 42b are directly connected, when a strong transverse electric field for aligning the liquid crystal molecules 3a in the vicinity of the linear portions 42a, 42b of the curved electrode 41 of the pixel electrode 4 to the molecular long axis substantially at 45 ° with respect to the alignment treatment directions 1a, 2a is generated between the pixel electrode 4 and the counter electrode 5, fig. 10 shows the molecular long axis direction of each of the liquid crystal molecules 3a in 1 pixel 100, and fig. 11 shows a cross section taken along the XI-XI line of fig. 9.

As shown in fig. 9 to 11, in the comparative example in which the plurality of bent electrodes 41 of the pixel electrode 4 are formed in the "<" shape in which the 2 linear portions 42a and 42b are directly connected, when a strong lateral electric field E is generated between the pixel electrode 4 and the counter electrode 5, the liquid crystal molecules 3a in the region S1 along the right edge of the upper linear portion 42a and the liquid crystal molecules 3a in the region S2 along the left edge of the lower linear portion 42b in fig. 9 are inclined at an inclination angle (an inclination angle in a direction inclined upward to the left and in a direction away from the rear substrate 2 in the figure from the molecule end side coated with a dark color) opposite to the inclination angle of the pretilt caused by the alignment treatment of the inner surfaces of the substrates (an inclination angle in a direction inclined upward to the right and away from the rear substrate 2 in the figure from the molecule end side coated with a dark color).

Therefore, in this comparative example, when a strong lateral electric field E is generated between the pixel electrode 4 and the counter electrode 5, the regions S1 and S2 where the liquid crystal molecules 3a are inversely tilted (tilted at a tilt angle opposite to the pre-tilt angle) and the other regions where the liquid crystal molecules 3a are not inversely tilted are formed in each pixel, and the tilt directions of the liquid crystal molecules 3a in these regions are different from each other, thereby causing alignment unevenness.

In contrast to this comparative example, in the liquid crystal display element according to the above-described embodiment, the portions of the 2 linear portions 42a and 42b of the plurality of bent electrodes 41 connected to the pixel electrode 4 are formed in such a shape that one side connected to one linear portion 42a is bent in a direction in which the inclination angle with respect to the alignment treatment direction 1a or 2a becomes larger with respect to the one linear portion 42a, and one side connected to the other linear portion 42b is bent in a direction in which the inclination angle with respect to the alignment treatment direction 1a or 2a becomes larger with respect to the other linear portion 42 b. Therefore, in the lateral electric field E generated between the pixel electrode 4 and the counter electrode 5, as shown in fig. 6, the lateral electric field E generated between one side edge and the other side edge of the curved portions 43a and 43b of the plurality of curved electrodes 41 of the pixel electrode 4 and the counter electrode 5 (electric field in the direction orthogonal to the side edges of the curved portions 43a and 43 b) is smaller in the intersecting angle with respect to the alignment treatment directions 1a and 2a than the lateral electric field E generated between one side edge and the other side edge of the linear portions 42a and 42b of the curved electrode 41 and the counter electrode 5.

In this way, since the change angle ψ b in the molecular long axis direction of the liquid crystal molecules 3a in the regions along the one side edge and the other side edge of the bent portions 43a, 43b due to the transverse electric field E is smaller than the change angle ψ a in the molecular long axis direction of the liquid crystal molecules 3a in the regions along the one side edge and the other side edge of the linear portions 42a, 42b with respect to the alignment treatment directions 1a, 2a, the alignment control force of the alignment film and the adjacent molecular force aligned by the alignment control force act strongly in the liquid crystal molecules 3a in the regions along the one side edge and the other side edge of the bent portions 43a, 43b than the force due to the transverse electric field E, and the change in the tilt angle of the liquid crystal molecules due to the transverse electric field E is suppressed.

Since the curved portions 43a and 43b are connected by a continuous curve, the discontinuity in the alignment of the liquid crystal molecules 3a in the region corresponding to the upper linear portion 42a and the lower linear portion 42b of the curved electrode 41 in the drawing is reduced, and thus the change in the tilt angle of the liquid crystal molecules is suppressed.

Therefore, even when a strong transverse electric field E for aligning the liquid crystal molecules 3a in the region along the linear portions 42a and 42b of the bent electrode 41 of the pixel electrode 4 to the molecular long axis in the direction substantially at 45 ° or in the vicinity thereof with respect to the alignment treatment directions 1a and 2a is generated between the pixel electrode 4 and the counter electrode 5, the tilt of the liquid crystal molecules in the vicinity of the bent portion is not inverted, but the molecular long axis direction is changed in a state where the tilt angle direction of the pre-tilt by the alignment treatment is tilted.

Therefore, as in the comparative examples shown in fig. 9 to 11, the starting point for reversely inclining the liquid crystal molecules 3a in the region along one side edge and the other side edge of the linear portions 42a and 42b of the curved electrode 41 does not occur in the portion corresponding to the curved point of the "<" -shaped curved electrode 41.

Since the 2 curved portions 43a and 43b connecting the 2 linear portions 42a and 42b and the connecting portions of the linear portions 42a and 42b are formed in the shape of circular arcs in which both side edges of one and the other are smoothly connected to each other, the liquid crystal molecules 3a in the respective regions corresponding to the linear portions 42a and 42b are aligned in the curved portions 43a and 43b in a substantially continuous state.

In this way, in this liquid crystal display element, even when a strong lateral electric field E for aligning the liquid crystal molecules 3a in the region along the linear portions 42a and 42b of the bent electrode 41 of the pixel electrode 4 to the long axis of the molecules in the direction substantially at 45 ° or in the vicinity thereof with respect to the alignment treatment directions 1a and 2a is generated between the pixel electrode 4 and the counter electrode 5, as shown in fig. 6 to 8, a good display quality without alignment unevenness is realized in the regions corresponding to the plurality of bent electrodes 41 of the pixel electrode 4.

In this liquid crystal display element, the end portions of the 2 linear portions 42a and 42b of the plurality of bent electrodes 41 of the pixel electrode 4 are connected to the linear portions 42a and 42b, respectively, and the end bent portions 44a and 44b bent in the direction in which the inclination angles with respect to the alignment treatment directions 1a and 2a become larger with respect to the linear portions 42a and 42b are formed, so that the transverse electric field E is generated between one side edge and the other side edge of the end bent portions 44a and 44b and the counter electrode 5, and the intersection angle with respect to the alignment treatment directions 1a and 2a is smaller than the transverse electric field E generated between one side edge and the other side edge of the linear portions 42a and 42b of the bent electrode 41 and the counter electrode 5.

In other words, the change angle ψ c in the molecular long axis direction of the liquid crystal molecules 3a in the region along the one side edge and the other side edge of the end bent portions 44a, 44b due to the transverse electric field E is smaller than the change angle ψ a in the molecular long axis direction of the liquid crystal molecules 3a in the region along the one side edge and the other side edge of the linear portions 42a, 42b with respect to the alignment treatment directions 1a, 2 a. Therefore, the molecular long axis direction of the liquid crystal molecules 3a in the region along the one side edge and the other side edge of the end bent portions 44a and 44b can be changed at the tilt angle of the pre-tilt by the alignment treatment without generating the reverse tilt by the lateral electric field E. Accordingly, the reverse tilt of the liquid crystal molecules 3a due to the lateral electric field E can be more effectively eliminated.

In this liquid crystal display element, the inclination angle θ a of the 2 straight portions 42a and 42b of the plurality of bent electrodes 41 of the pixel electrode 4 with respect to the alignment treatment directions 1a and 2a and the inclination angle θ b of the 2 bent portions 43a and 43b connecting the 2 straight portions 42a and 42b with respect to the alignment treatment directions 1a and 2a are set to:

0°＜θa＜20°

20°＜θb＜40°，

the reverse tilt of the liquid crystal molecules 3a due to the lateral electric field E can be more reliably eliminated.

In this liquid crystal display device, the length La of the 2 straight portions 42a and 42b of the plurality of bent electrodes 41 of the pixel electrode 4 and the length Lb of the 2 bent portions 43a and 43b connecting the 2 straight portions 42a and 42b are set to:

La＞nLb(n：3～5)，

10Lb＞La＞4Lb，

therefore, the effect of preventing the reverse tilt of the liquid crystal molecules 3a due to the bent portion can be sufficiently exhibited, and the display in the region corresponding to the bent portion can be hardly affected.

In this liquid crystal display element, the inclination angle θ c of the end bent portions 44a and 44b with respect to the alignment treatment directions 1a and 2a, which are formed at the ends of the 2 linear portions 42a and 42b of the plurality of bent electrodes 41 of the pixel electrode 4, is set as follows:

20°＜θc＜40°，

the reverse tilt of the liquid crystal molecules 3a due to the lateral electric field E can be more reliably eliminated.

In this liquid crystal display device, the length Lc of the end bent portions 44a and 44b is set to be, with respect to the length La of the linear portions 42a and 42b of the bent electrode 41:

La＞nLc(n：3～5)

10Lc＞La＞4Lc，

therefore, the effect of preventing the reverse tilt of the liquid crystal molecules 3a due to the end bent portions 44a and 44b can be sufficiently exhibited, and the display of the regions corresponding to the end bent portions 44a and 44b can be hardly affected.

In this liquid crystal display device, the inclination angle θ a of the 2 straight portions 42a, 42b of the plurality of bent electrodes 41 of the pixel electrode 4 with respect to the alignment treatment directions 1a, 2a is preferably set to 10 ° ± 5 °, more preferably 10 ° ± 2 °, and the inclination angles θ b, θ c of the bent portions 43a, 43b and the end bent portions 44a, 44b connecting the 2 straight portions 42a, 42b with respect to the alignment treatment directions 1a, 2a are preferably set to 30 ° ± 5 °, more preferably 30 ° ± 2 °, so that the reverse tilt of the liquid crystal molecules 3a due to the transverse electric field E can be more reliably eliminated.

Further, in the above-described embodiment, the plurality of bent electrodes 41 of the pixel electrode 4 are connected in common at both ends, respectively, but the plurality of bent electrodes 41 may be connected in common at one end (the end on the side connected to the TFT 6).

In the above embodiment, the counter electrode 5 is formed in a shape corresponding to the entire region of the pixel 100, but the counter electrode 5 may correspond to at least a plurality of the curved electrodes 41 and 41 of the pixel electrode 4.

In the liquid crystal display element of the above embodiment, the 1 st electrode on the liquid crystal layer 3 side among the 1 st and 2 nd electrodes insulated from each other on the inner surface of the rear substrate 2 is made to be the plurality of pixel electrodes 4 arranged in a matrix, and the 2 nd electrode on the rear substrate 2 side is made to be the counter electrode 5, but in contrast to this configuration, the 1 st electrode on the liquid crystal layer 3 side may be made to be the counter electrode, and the 2 nd electrode on the rear substrate 2 side may be made to be the plurality of pixel electrodes 4 arranged in a matrix, in which case, a plurality of bend electrodes may be formed at the counter electrode, and the pixel electrode may be formed in a shape corresponding to the entire pixel or in a shape corresponding to the space between the plurality of bend electrodes of the counter electrode.

In the above embodiment, the 1 st and 2 nd electrodes are provided on the inner surface of the rear substrate 2, but the 1 st and 2 nd electrodes may be provided on the inner surface of the front substrate 1.

As described above, the liquid crystal display element of the present invention is characterized in that: the substrate processing apparatus includes a pair of substrates arranged opposite to each other with a predetermined gap therebetween, and on inner surfaces facing each other, alignment processing is performed in directions parallel to each other; a liquid crystal layer sealed in a gap between the pair of substrates, aligned such that a molecular long axis of liquid crystal molecules is aligned with the alignment treatment direction, and aligned substantially parallel to the substrate surfaces; one and the other straight line portions provided on an inner face of one of mutually opposed inner faces of the pair of substrates, extending in directions intersecting at respectively different angles with respect to the direction of the alignment treatment in each predetermined region for forming 1 pixel; a curved portion provided at each of adjacent ends of the one and the other linear portions and extending in a direction intersecting the direction of the orientation treatment at an angle larger than an intersection angle of the one and the other linear portions opposed to the direction of the orientation treatment with the direction of the orientation treatment; a plurality of 1 st electrodes each including a connection portion connecting the bent portions; and a 2 nd electrode arranged on an inner surface of the one substrate so as to be insulated from the 1 st electrode, wherein a transverse electric field for changing a direction of a molecular long axis of the liquid crystal molecule in a plane substantially parallel to the substrate surface is generated between the 2 nd electrode and the 1 st electrode.

In the liquid crystal display device, the 1 st electrode is formed of a plurality of elongated linear portions arranged at intervals in parallel, and is preferably connected to each pixel at least on one end side of the linear portions. Preferably, the 1 st electrode is formed of a transparent conductive film other than the transparent conductive film removed by the plurality of slits, in which the plurality of slits for forming the plurality of linear portions are formed in the transparent conductive film having an area corresponding to a predetermined region for forming the 1 pixel. Preferably, the 1 st electrode is formed by applying an electric field between the 1 st electrode and the 2 nd electrode to form 2 regions for aligning the liquid crystal molecules in a longitudinal direction in a 1 st direction and a 2 nd direction which are different from each other, one linear portion of the 1 st electrode is formed in one of the 2 regions, and the other linear portion of the 1 st electrode is formed in the other of the 2 regions. The side edge of the connecting portion of the 1 st electrode is preferably formed as a continuous curved surface.

In the liquid crystal display device, it is preferable that the 2 nd electrode is arranged between the 1 st electrode on the one substrate and the one substrate so as to be insulated from the 1 st electrode.

In the liquid crystal display device, when the inclination angle of the one and the other straight portions of the 1 st electrode with respect to the alignment treatment direction is represented by θ a, and the inclination angle of each of the bent portions provided at the end portions of the 2 adjacent straight portions with respect to the alignment treatment direction is represented by θ b, the inclination angle θ a of the straight portion and the inclination angle θ b of the bent portion are preferably set to 0 ° < θ a < 20 °, and 20 ° < θ b < 40 °. When the length of one and the other straight portions of the 1 st electrode is La and the length of the bent portion is Lb, the 2 lengths La and Lb are preferably La > nLb (n: 3 to 5) and 10Lb > La > 4 Lb.

In the liquid crystal display element, the 1 st electrode is preferably formed as an end portion bent portion which is provided so as to be connected to the linear portion at least at one end of end portions of one and the other linear portions thereof on the opposite side of one end adjacent to each other, and which is bent in a direction in which an inclination angle with respect to the alignment treatment direction becomes larger with respect to the linear portion. In this case, when the inclination angle of the end portion bent portion with respect to the orientation processing direction is θ c, it is desirable that the inclination angle θ c is set to 20 ° < θ c < 40 °. When the length of the straight portion is La and the length of the end portion bent portion is Lc, the length Lc of the end portion bent portion is preferably La > nLc (n: 3-5), and 10Lc > La > 4 Lc.

Claims (10)

1. A liquid crystal display element is characterized by comprising:

a pair of substrates disposed opposite to each other with a predetermined gap therebetween, and subjected to alignment treatment in directions parallel to each other on inner surfaces facing each other;

a liquid crystal layer sealed in a gap between the pair of substrates, having long molecular axes of liquid crystal molecules aligned in the alignment direction, and aligned substantially parallel to the substrate surfaces;

a plurality of 1 st electrodes provided on an inner surface of one of the opposed inner surfaces of the pair of substrates, the plurality of 1 st electrodes including: one and the other straight line portions extending in directions intersecting at respectively different angles with respect to the direction of the above-described alignment treatment in each predetermined region for forming 1 pixel; curved portions provided at mutually adjacent ends of the one and the other linear portions, respectively, and extending in a direction intersecting the direction of the orientation treatment at an angle larger than an intersection angle of the one and the other linear portions with the direction of the orientation treatment, respectively; and a connecting portion connecting the bent portions; and

a 2 nd electrode arranged on an inner surface of the one substrate so as to be insulated from the 1 st electrode, and generating a transverse electric field between the 2 nd electrode and the 1 st electrode for changing a direction of a molecular long axis of the liquid crystal molecules in a plane substantially parallel to the substrate surface,

when the inclination angle of one and the other linear portions of the 1 st electrode with respect to the orientation treatment direction is represented as thetaa, and the inclination angle of each of the bent portions provided at the end portions of the 2 adjacent linear portions with respect to the orientation treatment direction is represented as thetab, the inclination angles are set to 0 ° < thetaa < 20 °, 20 ° < thetab < 40 °,

the length of one and the other straight portions of the 1 st electrode is La, and the length of the bent portion is Lb, the length is set

La > nLb and 10Lb > La > 4Lb, n: 3 to 5.

2. The liquid crystal display element according to claim 1, wherein the 1 st electrode is formed of a plurality of elongated linear portions arranged at intervals in parallel, and is connected to each pixel at least one end of the linear portion.

3. The liquid crystal display element according to claim 1, wherein the 1 st electrode is formed by forming a plurality of slits for forming the plurality of linear portions in a transparent conductive film having an area corresponding to a predetermined region for forming the 1 pixel, and by forming a transparent conductive film other than the transparent conductive film by removing the plurality of slits.

4. The liquid crystal display element according to claim 1, wherein the 1 st electrode is provided so as to form 2 regions for aligning the liquid crystal molecules in the 1 st direction and the 2 nd direction which are different from each other by applying an electric field between the 1 st electrode and the 2 nd electrode, one linear portion of the 1 st electrode is formed in one of the 2 regions, and the other linear portion of the 1 st electrode is formed in the other of the 2 regions.

5. The liquid crystal display element according to claim 1, wherein the 2 nd electrode is provided so as to be insulated from the 1 st electrode and disposed between the 1 st electrode on the one substrate and the one substrate.

6. The liquid crystal display element according to claim 1, wherein a side edge of the connecting portion of the 1 st electrode is formed as a continuous curved surface.

7. The liquid crystal display element according to claim 1, wherein the 1 st electrode is formed with an end portion bent portion which is provided so as to be connected to the one linear portion at least at one end of end portions of the one and the other linear portions of the first electrode on a side opposite to one end adjacent to each other, and which extends in a direction intersecting with the alignment treatment direction at an angle larger than an intersection angle of the one and the other linear portions with respect to the alignment treatment direction.

8. The liquid crystal display element according to claim 7, wherein when the inclination angle of the end portion bent portion with respect to the alignment treatment direction is θ c, the inclination angle θ c is set to

20°＜θc＜40°。

9. The liquid crystal display element according to claim 8, wherein the length of the straight portion is La and the length of the end portion bent portion is Lc, respectively

La > nLc and 10Lc > La > 4Lc, n: 3 to 5.

10. A liquid crystal display element is characterized by comprising:

a pair of substrates disposed opposite to each other with a predetermined gap therebetween, and subjected to alignment treatment in directions parallel to each other on inner surfaces facing each other;

a liquid crystal layer sealed in a gap between the pair of substrates, having long molecular axes of liquid crystal molecules aligned in the alignment direction, and aligned substantially parallel to the substrate surfaces;

a plurality of 1 st electrodes provided on an inner surface of one of the opposed inner surfaces of the pair of substrates, the plurality of 1 st electrodes including: one and the other straight line portions extending in directions intersecting at respectively different angles with respect to the direction of the above-described alignment treatment in each predetermined region for forming 1 pixel; curved portions provided at mutually adjacent ends of the one and the other linear portions, respectively, and extending in a direction intersecting the direction of the orientation treatment at an angle larger than an intersection angle of the one and the other linear portions with the direction of the orientation treatment, respectively; and a connecting portion connecting the bent portions; and

a 2 nd electrode arranged on an inner surface of the one substrate so as to be insulated from the 1 st electrode, and generating a transverse electric field between the 2 nd electrode and the 1 st electrode for changing a direction of a molecular long axis of the liquid crystal molecules in a plane substantially parallel to the substrate surface,

the 1 st electrode is provided so as to form 2 regions for aligning the liquid crystal molecules in the longitudinal direction in the 1 st direction and the 2 nd direction which are different from each other by applying an electric field between the 1 st electrode and the 2 nd electrode, one linear portion of the 1 st electrode is formed in one of the 2 regions, and the other linear portion of the 1 st electrode is formed in the other of the 2 regions,

the length of one and the other straight portions of the 1 st electrode is La, and the length of the bent portion is Lb, the length is set

La > nLb and 10Lb > La > 4Lb, n: 3 to 5.