JP2008083395A - Liquid crystal display element - Google Patents

Abstract

A lateral electric field control type liquid crystal display device having a wide field of view and good display quality without causing display unevenness is provided.
A liquid crystal layer made of a nematic liquid crystal having negative dielectric anisotropy is sealed between a pair of substrates that are parallel to each other and subjected to orientation treatment in opposite directions on each of inner surfaces facing each other. A plurality of elongated electrode portions 41 are formed in parallel in a predetermined unit region for forming one pixel on the inner surface of the substrate 2 at intervals, and the plurality of elongated electrode portions 41 are respectively formed A plurality of pixels which are bent into a substantially “<” shape and whose two elongated sides 42 a and 42 b intersect with the alignment processing directions 1 a and 2 a at substantially the same angle. An electrode 4 and a counter electrode 5 that is disposed on the substrate 2 side of the electrode 4 and is insulated from the pixel electrode 4 and generates a lateral electric field between the plurality of elongated electrode portions 41 of the pixel electrode 4 are provided.
[Selection] Figure 1

Description

  The present invention relates to a lateral electric field control type liquid crystal display element.

  As a liquid crystal display element, a positive dielectric anisotropy is provided in a gap between a pair of substrates that are arranged opposite to each other with a predetermined gap and that are parallel to each other and subjected to orientation treatment in opposite directions on the inner surfaces facing each other. A liquid crystal layer composed of a nematic liquid crystal having the property of being aligned with the molecular major axis of liquid crystal molecules aligned in the alignment treatment direction and substantially parallel to the substrate surface, and being one of the pair of substrates A plurality of elongated electrode portions formed in parallel in a predetermined unit region for forming one pixel on the inner surface of the inner surface of the inner surface of the inner surface of the first electrode; Between the plurality of elongated electrode portions of the first electrode by applying a voltage between the first electrode and the first electrode. The orientation of the molecular long axis of the liquid crystal molecules is substantially flat with the substrate surface. There is a lateral electric field control type provided with a second electrode for generating a transverse electric field is changed to a direction.

  The lateral electric field control type liquid crystal display element generates the lateral electric field corresponding to display data between the plurality of elongated electrode portions of the first electrode, the second electrode, and the electrodes, thereby the first and second electrodes. An image is displayed by controlling the orientation of the molecular major axis of the liquid crystal molecules of a plurality of pixels composed of regions corresponding to the electrodes in a plane substantially parallel to the substrate surface.

By the way, in the lateral electric field control type liquid crystal display element, a plurality of elongated electrode portions of the first electrode are bent into a “<” shape in order to display a wide field of view without a color shift due to a viewing angle. The direction of the transverse electric field generated between one of the two elongated sides and the second electrode sandwiching the bent portion and the second electrode, and the other elongated side and the first It is desired to arrange liquid crystal molecules in two different directions in each pixel by making the directions of the transverse electric field generated between the two electrodes different from each other (see Patent Document 1).
JP 2002-182230 A

  However, a lateral electric field control type liquid crystal display element formed by bending a plurality of elongated electrode portions of the first electrode into a “<” shape is formed when the strong lateral electric field is generated. The liquid crystal molecules in the region along one side edge of one elongated side portion and the liquid crystal molecules in the region along the other side edge of the other elongated side portion of the elongated electrode portion are inclined by a pretilt due to the alignment treatment on the inner surface of the substrate. It has the problem of tilting in the opposite direction to causing display unevenness.

  An object of the present invention is to provide a lateral electric field control type liquid crystal display element having a wide field of view and good display quality without display unevenness.

The liquid crystal display element of the present invention is
A pair of substrates that are arranged opposite to each other with a predetermined gap, and each of the inner surfaces facing each other is subjected to alignment treatment in parallel and in opposite directions;
The nematic liquid crystal is sealed in the gap between the pair of substrates and has negative dielectric anisotropy, and the liquid crystal molecules are aligned substantially parallel to the substrate surface with the molecular long axes aligned with the alignment treatment direction. Liquid crystal layer,
A plurality of elongated electrode portions are arranged in parallel in a predetermined unit region for forming one pixel, which is provided on the inner surface of one of the pair of substrates facing each other. A first electrode formed in a shape intersecting each other at one end of two elongated side portions that are formed and each of the plurality of elongated electrode portions extends at a different angle with respect to the direction of the alignment treatment;
The first electrode on the inner surface of one substrate is disposed closer to the first substrate than the first electrode, and the first electrode is applied by applying a voltage between the first electrode and the first electrode. A second electrode that generates a transverse electric field that changes the direction of the molecular major axis of the liquid crystal molecules in a direction substantially parallel to the substrate surface between the plurality of elongated electrode portions of the electrode;
It is provided with.

  According to the liquid crystal display element of the present invention, the alignment unevenness in which the liquid crystal molecules are tilted at a tilt opposite to the pretilt tilt by the alignment treatment is suppressed, and a good display quality without display unevenness can be obtained.

  1 to 6 show an embodiment of the present invention. FIG. 1 is a plan view of a part of one substrate of a liquid crystal display element, and FIG. 2 is taken along the line II-II in FIG. It is sectional drawing.

  As shown in FIGS. 1 and 2, the liquid crystal display element includes a pair of transparent substrates 1 and 2 on the observation side (upper side in FIG. 2) and the opposite side arranged opposite to each other with a predetermined gap therebetween. Liquid crystal layer 3 sealed in the gap between the substrates 1 and 2 and the inner surface of one of the opposing inner surfaces of the pair of substrates 1 and 2, for example, the inner surface of the substrate 2 opposite to the observation side In addition, a lateral electric field substantially parallel to the surfaces of the substrates 1 and 2 is generated by applying a voltage, and the orientation of the molecular major axis of the liquid crystal molecules of the liquid crystal layer 3 is controlled by the lateral electric field. First and second transparent electrodes 44 for forming a plurality of pixels 100 arranged in a matrix, and a pair of observation sides and opposite pairs arranged on the outer surfaces of the pair of substrates 1 and 2, respectively. Polarizing plates 19 and 20 are provided.

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

  The pair of substrates 1 and 2 are joined via a frame-shaped sealing material (not shown), and the liquid crystal layer 3 is in a region surrounded by the sealing material in the gap between the pair of substrates 1 and 2. It is enclosed.

  This liquid crystal display element is an active matrix liquid crystal display element. Of the first and second electrodes 44 provided on the inner surface of the rear substrate 2 so as to be insulated from each other, the first electrode 4 has a row direction (screen). A plurality of pixel electrodes and second electrodes 5 arranged in a matrix in the column direction (vertical direction of the screen) correspond to each pixel electrode 4 in that row for each row. It is the counter electrode arrange | positioned.

  A plurality of active elements 6 disposed on the inner surface of the rear substrate 2 so as to correspond to the plurality of pixels 100 each having a region corresponding to the plurality of pixel electrodes 4 and the counter electrode 5; A plurality of scanning lines 12 arranged for each pixel row composed of a plurality of pixels 100 arranged in the row direction, and a plurality of scanning lines arranged for each pixel column composed of the plurality of pixels 100 arranged in the column direction. A signal line 13 is provided.

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

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

  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 the gate of the TFT 6 in each row. The plurality of signal lines 13 connected to the electrodes 7 are formed on the gate insulating film 8 in parallel with the pixel columns along one side (left side in FIG. 1) of the pixel columns. And connected to the drain electrode 10 of the TFT 6 in each column.

  Note that a terminal array portion (not shown) extending outward from 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 A plurality of scanning line terminals and signal line terminals provided in the terminal array portion are connected.

  The plurality of pixel electrodes 4 are formed on a 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. Is formed on the gate insulating film 8. In other words, the counter electrode 5 is disposed on the rear substrate 2 side of the plurality of pixel electrodes 4 so as to be insulated from the plurality of pixel electrodes 4 by the interlayer insulating film 14.

  Each of the plurality of pixel electrodes 4 is a predetermined unit region for forming one pixel 100, for example, a vertically long rectangle whose vertical width along the vertical direction of the screen is larger than the horizontal width along the horizontal direction of the screen. A first transparent conductive film (for example, an ITO film) in which a plurality of elongated electrode portions 41 having a length extending over substantially the entire length in the vertical width direction of the unit region are formed in parallel in the shape region at intervals. 40).

  Note that the plurality of elongated electrode portions 41 of the pixel electrode 4 are connected to a common connection portion 43 formed at one end edge of the first conductive film 40, and the common connection of the first conductive film 40. One end of the portion 43 is overlaid on the source electrode 11 of the TFT 6 via the interlayer insulating film 14 and is connected to the source electrode 11 in a contact hole (not shown) provided in the interlayer insulating film 14.

  The counter electrode 5 includes a second transparent conductive film (for example, an ITO film) 50 provided over the entire length of each pixel row and formed in a shape corresponding to the entire area of the plurality of pixels 100 in each row. ing.

  In this embodiment, as shown in FIG. 1, the second conductive film 50 is patterned into a vertically-long rectangular electrode portion 51 corresponding to the pixel shape in a region corresponding to each of the plurality of pixels 100 in each row. These rectangular electrode portions 51 are formed in a shape connected by a common connection portion 52 at one end side (the side opposite to the side where the scanning line 12 is provided). 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.

  The second conductive film 50 is formed across the plurality of signal lines 13, and an intersection between the conductive film 50 and the signal lines 13 is provided so as to cover the signal lines 13. It is insulated by an insulating film (not shown).

  The plurality of second conductive films 50 corresponding to the respective pixel rows are commonly connected (not shown) outside one end side of the arrangement region of the plurality of pixel electrodes 4, and the common connection portion Is connected to a counter electrode terminal provided in the terminal array portion of the rear substrate 2.

  The counter electrode 5 made of the second conductive film 50 is connected to the plurality of elongated electrode portions 41 of the pixel electrode 4 by applying a voltage between the counter electrode 5 and the pixel electrode 4. A transverse electric field that changes the direction of the major axis in a direction substantially parallel to the surfaces of the substrates 1 and 2 is generated.

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

  Further, the inner surfaces of the pair of substrates 1 and 2 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. Horizontal alignment films 17 and 18 such as a polyimide film having an orientation for aligning the liquid crystal molecules 3a of the layer 3 with the molecular major axis in a direction substantially parallel to the surfaces of the substrates 1 and 2 are formed.

  The inner surfaces of the pair of substrates 1 and 2 are aligned in parallel and in opposite directions by rubbing the film surfaces of the alignment films 17 and 18 in predetermined directions, respectively.

  FIG. 3 is an enlarged plan view of a part of the pixel electrode 4 and the counter electrode 5. In FIGS. 1 and 3, reference numeral 1a denotes an alignment treatment direction (rubbing direction of the alignment film 17) on the inner surface of the front substrate 1, and reference numeral 2a denotes a rear surface. The orientation processing direction (the rubbing direction of the orientation film 18) on the inner surface of the substrate 1 is shown.

  In this embodiment, the inner surface of the front substrate 1 is oriented in parallel with the left-right direction of the screen from the right direction of the screen to the left direction, and the inner surface of the rear substrate 2 is directed from the left direction of the screen to the right direction. Orientation processing in parallel with the horizontal direction of the screen.

  Each of the plurality of elongated electrode portions 41 of the pixel electrode 4 is formed by crossing two elongated side portions 42a and 42b at different angles with respect to the alignment processing directions 1a and 2a, respectively, as shown in FIG. In the central portion of the rectangular unit region in the vertical width direction, the two elongated sides 42a and 42b are substantially bent into a "<" shape connected at the intersecting portions. .

The two elongated side portions 42a and 42b of the elongated electrode portion 41 are formed to have substantially the same width, and the width W1 of _one elongated side portion 42a and the adjacent elongated electrode portion 41 are adjacent to each other. the one of the elongated side portion 42a, the ratio _{D 1} / _W 1, and the width _{W 2} of the other elongate side portion 42b of the spacing _{D 1} of the inter-42a, adjacent elongate the other elongate side portion 42b of the electrode portion 41 , 42b, the ratio D ₂ / W _{2 to} the distance D ₂ is set to 1/3 to 3/1, preferably 1/1.

The inclination angle of the two elongated side portions 42a and 42b of the plurality of elongated electrode portions 41 of the pixel electrode 4 with respect to the alignment processing directions 1a and 2a (left and right direction of the screen) is θ.
70 ° <θ <90 °
Is set to

  The inclination angle θ of the elongated side portions 42a, 42b with respect to the alignment processing directions 1a, 2a is preferably set to 80 ° ± 5 °, more preferably 80 ° ± 2 °.

  The liquid crystal layer 3 is made of nematic liquid crystal having negative dielectric anisotropy, and the liquid crystal molecules 3a of the liquid crystal layer 3 have the molecular major axis aligned with the alignment treatment directions 1a and 2a. It is arranged substantially parallel to the first and second surfaces.

  FIG. 4 is an enlarged cross-sectional view in which hatching along the line VV in FIG. 3 is omitted. As shown in FIGS. 3 and 4, the liquid crystal molecules 3a have molecular long axes in the alignment treatment directions 1a and 2a. The substrate 1 in a state of being aligned and pretilted in a direction away from the rear substrate 2 toward the orientation processing direction 2a of the inner surface of the rear substrate 2 with respect to one substrate surface, for example, the rear substrate 2 surface. They are arranged substantially parallel to the two surfaces.

  Further, between the front substrate 1 and the front polarizing plate 19 disposed on the outer surface thereof, a single film-like transparent static electricity shielding conductive material for shielding static electricity from the outside over the entire surface of the front substrate 1. A membrane 21 is provided.

  The liquid crystal display element applies a driving voltage corresponding to display data between the pixel electrode 4 and the counter electrode 5 of the plurality of pixels 100, whereby the plurality of elongated electrode portions 41 of the pixel electrode 4 A transverse electric field is generated between the counter electrode 5 and the major axis of the liquid crystal molecules 3 a in a direction substantially parallel to the surfaces of the substrates 1 and 2. The direction of the molecular long axis of the liquid crystal molecules 3a is controlled in a plane substantially parallel to the surfaces of the substrates 1 and 2 to display an image.

  The drive voltage applied between the pixel electrode 4 and the counter electrode 5 is from the minimum value of substantially 0V that does not generate the lateral electric field according to display data, and the elongated electrode portion 41 of the pixel electrode 4 is elongated. The maximum generation of a lateral electric field with a strength that aligns the liquid crystal molecules 3a in the region along the side portions 42a and 42b with the molecular major axis in a direction substantially 45 ° with respect to the alignment processing directions 1a and 2a. Controlled by a range of values.

  In the liquid crystal display element of this embodiment, for example, one transmission axis of the front polarizing plate 19 and the rear polarizing plate 20 is substantially parallel to or substantially orthogonal to the alignment processing directions 1a and 2a. And the pixel electrode 4 is of a non-electric field dark display type (hereinafter referred to as normally black type) in which the transmission axis of the other polarizing plate is substantially perpendicular to the transmission axis of the one polarizing plate. When no horizontal electric field is generated between the electrode 100 and the counter electrode 5, that is, when the liquid crystal molecules 3a are aligned in the alignment treatment directions 1a and 2a with the molecular long axes aligned as shown in FIG. The display becomes black, and the liquid crystal molecules 3a are arranged between the pixel electrode 4 and the counter electrode 5 with the molecular major axis in a direction substantially 45 ° to the alignment treatment directions 1a and 2a. When a horizontal electric field having a sufficient strength is generated, the pixel 100 Display is the brightest light display.

  FIG. 5 shows that the liquid crystal molecules 3a are arranged between the pixel electrode 4 and the counter electrode 5 so that the molecular major axis is aligned in a direction substantially 45 ° with respect to the alignment processing directions 1a and 2a. FIG. 6 is an enlarged cross-sectional view in which hatching along the line VI-VI in FIG. 5 is omitted, and FIG. 6 is a plan view showing the orientation of the molecular major axis of the liquid crystal molecules 3a of each part in one pixel 100 when a horizontal electric field is generated. 7 is an enlarged sectional view in which hatching along the line VII-VII in FIG. 5 is omitted.

  As shown in FIGS. 5 and 7, the lateral electric field E includes one side edge and the other side edge of the plurality of elongated electrode portions 41 of the pixel electrode 4, and a portion of the counter electrode 5 adjacent to the elongated electrode portion 41. Generate during.

  The horizontal electric field E is an electric field in a direction orthogonal to the side edges of the plurality of elongated electrode portions 41 of the pixel electrode 4, and the liquid crystal molecules 3 a generate a strong electric field by the generation of the horizontal electric field E. Change the direction accordingly.

  In this liquid crystal display element, the plurality of elongated electrode portions 41 of the pixel electrode 4 are bent into a substantially “<” shape, and the two elongated side portions 42 a and 42 b are respectively connected to the pair of substrates 1. , 2 are formed so as to intersect at substantially the same angle with respect to the alignment processing directions 1a, 2a of the inner surfaces of the plurality of elongated electrode portions 41 of the pixel electrode 4, as shown in FIG. The direction of the horizontal electric field E generated between one elongated side portion 42 a and the counter electrode 5 and the horizontal electric field E generated between the other elongated side portion 42 b of the elongated electrode portion 41 and the counter electrode 5. The liquid crystal molecules 3a are arranged in two different directions in each pixel 100 so that a wide-field display without color shift due to the viewing angle can be performed.

  In addition, in this liquid crystal display element, the liquid crystal layer 3 made of nematic liquid crystal having negative dielectric anisotropy is formed in the gap between the pair of substrates 1 and 2, and the molecular major axis of the liquid crystal molecules 3a is set in the alignment processing direction 1a. , 2a aligned and substantially parallel to the surfaces of the substrates 1 and 2, and sealed, the liquid crystal molecules 3a are placed between the pixel electrode 4 and the counter electrode 5 in the alignment processing direction 1a. , 2a, the liquid crystal molecules 3a have a tilt opposite to the tilt of the pretilt due to the alignment process even when a strong transverse electric field E is generated with the molecular long axis oriented substantially 45 ° or close to it. Will never tilt.

  That is, the lateral electric field E is generated between one side edge and the other side edge of the plurality of elongated electrode portions 41 of the pixel electrode 4 and a portion adjacent to the elongated electrode portion 41 of the counter electrode 5. The lateral electric field E generated between one side edge of the elongated electrode part 41 and the counter electrode 5 and the lateral electric field E generated between the other side edge of the elongated electrode part 41 and the counter electrode 5 are adjacent to each other. The electric fields are opposite to each other when viewed from the central direction between the elongated electrode portions 41 and 41 that are fitted.

  Further, the plurality of elongated electrode portions 41 of the pixel electrode 4 are bent substantially in a “<” shape, and the two elongated side portions 42 a and 42 b are substantially in the alignment processing directions 1 a and 2 a, respectively. Therefore, the transverse electric field E generated between one side edge and the other side edge of one elongated side portion 42a of the elongated electrode portion 41 and the counter electrode 5 is formed. And an electric field in a direction obliquely intersecting one direction with respect to the alignment processing directions 1a and 2a, and the one side edge and the other side edge of the other elongated side portion 42b of the elongated electrode portion 41 and the counter electrode 5 The horizontal electric field E generated between the first and second thin films 42a and 2a is an electric field that obliquely intersects with the orientation processing directions 1a and 2a in the direction opposite to the horizontal electric field E on the one long side portion 42a side.

  That is, the horizontal electric field generated on the one side edge side of the horizontal electric field E generated between the one side edge and the other side edge of the elongated side part 42 a of the elongated electrode part 41 of the pixel electrode 4 and the counter electrode 5. A lateral electric field E generated on the other side edge side of an electric field E and a lateral electric field E generated between one side edge and the other side edge of the other elongated side part 42 b of the elongated electrode part 41 and the counter electrode 5. Are respectively electric fields (hereinafter referred to as reverse electric fields) in which the liquid crystal molecules 3a are tilted at a tilt opposite to the tilt of the pretilt by the alignment treatment of the inner surface of the substrate.

  On the other hand, the direction of change in the direction of the molecular long axis of the liquid crystal molecules due to the transverse electric field E (the direction of change from the no-field state in which the molecular long axes are aligned in the alignment treatment directions 1a and 2a) In contrast, when the dielectric anisotropy of the liquid crystal is positive, the liquid crystal molecules change the direction in which the angle of the molecular major axis with respect to the direction of the transverse electric field E decreases.

  In FIG. 8, the pixel electrode 4 is formed in the same shape as in the above embodiment, the inner surfaces of the pair of substrates 1 and 2 are aligned in a direction parallel to the vertical direction of the screen, and between the pair of substrates 1 and 2. In a comparative example in which a liquid crystal layer made of nematic liquid crystal having positive dielectric anisotropy is sealed in the gap, liquid crystal molecules are placed between the pixel electrode 4 and the counter electrode 5 in the alignment processing directions 1a and 2a. FIG. 9 is a plan view showing the orientation of the molecular major axis of the liquid crystal molecules in each part in one pixel 100 when a transverse electric field having a strength to align the molecular major axis in a substantially 45 ° direction is generated. FIG. 10 is an enlarged sectional view in which hatching along the line IX-IX in FIG. 8 is omitted, and FIG. 10 is an enlarged sectional view in which hatching along the line XX in FIG. 8 is omitted.

  As shown in FIG. 8, when the dielectric anisotropy of the liquid crystal is positive, the liquid crystal molecules 3b have a direction in which the angle of the molecular major axis with respect to the direction of the transverse electric field E decreases due to the generation of the transverse electric field E. That is, the direction is changed in the counterclockwise direction in FIG.

  When the transverse electric field E is a weak electric field that changes the molecular major axis direction of the liquid crystal molecules 3b at a small angle with respect to the alignment treatment directions 1a and 2a, that is, the tilt of the transverse electric field E acting on the liquid crystal molecules 3b. When the alignment force is weaker than the pretilt alignment force (alignment force of the alignment films 17 and 18) obtained by the alignment treatment on the inner surface of the substrate, the liquid crystal molecules 3b are also in the reverse electric field generating region due to the alignment force on the inner surface of the substrate. The direction is changed in a tilted state in the tilt direction of the pretilt by the alignment treatment of the substrate inner surface.

  However, when the lateral electric field E is a strong electric field that changes the molecular major axis direction of the liquid crystal molecules 3b at a large angle with respect to the alignment processing directions 1a and 2a, the tilt of the lateral electric field E acting on the liquid crystal molecules 3b. The alignment force becomes stronger than the pretilt alignment force due to the alignment process on the inner surface of the substrate, and in FIG. 8, the liquid crystal molecules 3b in the reverse electric field generation region S1 along the right edge of the upper elongated side portion 42a and the lower elongated shape. The liquid crystal molecules 3b in the reverse electric field generating region S2 along the left edge of the side portion 42b are inclined by the pre-tilt due to the alignment process (in the figure, obliquely downward to the right when viewed from the end of the thickly painted molecule). Tilt to an inclination opposite to the inclination away from 2) (an inclination away from the rear substrate 2 toward the diagonally upper left direction).

  For this reason, in this comparative example, when a strong lateral electric field E is generated between the pixel electrode 4 and the counter electrode 5, the reverse tilt (pretilt) of the liquid crystal molecules 3a is applied to the reverse electric field generation regions S1 and S2 in the pixel. Display unevenness due to a tilt that is opposite to the tilt of.

  In contrast to this comparative example, in the liquid crystal display element of the above embodiment, the pixel electrode 4 is formed in the shape as described above, and the inner surfaces of the pair of substrates 1 and 2 are aligned in a direction perpendicular to the vertical direction of the screen. In addition, since the liquid crystal layer 3 made of nematic liquid crystal having negative dielectric anisotropy is sealed in the gap between the pair of substrates 1 and 2, the liquid crystal molecules 3b of the liquid crystal layer 3 are The generation of E changes the direction in which the angle of the molecular long axis with respect to the direction of the transverse electric field E increases, that is, the clockwise direction in FIG.

  Therefore, in this liquid crystal display element, the liquid crystal molecules 3a are arranged between the pixel electrode 4 and the counter electrode 5 with the molecular major axis in a direction substantially 45 ° with respect to the alignment treatment directions 1a and 2a. Even when the strongest transverse electric field E to be generated is generated, the angle ψa (45 °) in the molecular major axis direction with respect to the alignment treatment directions 1a and 2a is the angle in the molecular major axis direction of the liquid crystal molecules 3a with respect to the direction of the lateral electric field E. It is smaller than ψb.

  For this reason, the liquid crystal molecules 3a are arranged between the pixel electrode 4 and the counter electrode 5 with the molecular major axis oriented substantially at 45 ° or close to the alignment processing directions 1a and 2a. Even when the horizontal electric field E is generated, a region along one side edge and the other side edge of the elongate electrode portion 41a of the elongate electrode portion 41 of the pixel electrode 4, that is, the liquid crystal molecules 3a is pre-tilted by the alignment treatment on the inner surface of the substrate. A region in which a lateral electric field E is generated that is tilted to the same tilt direction as the tilt direction and a lateral electric field E in a reverse direction that tilts the liquid crystal molecules 3a to a tilt opposite to the tilt direction of the pretilt by the alignment treatment on the inner surface of the substrate is generated. Both the liquid crystal molecules 3a in the region to be changed change the molecular major axis direction in a state where the liquid crystal molecules 3a are tilted in the tilt direction of the pretilt by the alignment treatment without causing reverse tilt due to the lateral electric field E.

  As described above, in the liquid crystal display element, even when a strong lateral electric field E is generated between the pixel electrode 4 and the counter electrode 5, the liquid crystal molecules 3a have an inclination opposite to the inclination of the pretilt due to the alignment treatment. Therefore, as shown in FIGS. 5 to 7, the tilt of the liquid crystal molecules 3 a in the region along the one side edge and the other side edge over the entire length of the plurality of elongated electrode portions 41 of the pixel electrode 4, as shown in FIGS. It is possible to obtain a good display quality with the same direction and no display unevenness.

Further, the liquid crystal display element has an inclination angle θ with respect to the alignment processing directions 1a and 2a of the two elongated side portions 42a and 42a of the plurality of elongated electrode portions 41 of the pixel electrode 4,
70 ° <θa <90 °
Therefore, the reverse tilt of the liquid crystal molecules due to the lateral electric field can be effectively eliminated.

  The inclination angle θ of the elongated side portions 42a, 42b with respect to the alignment processing directions 1a, 2a is preferably set to 80 ° ± 5 °, more preferably 80 ° ± 2 °. The reverse tilt of the liquid crystal molecules 3a due to the lateral electric field E can be eliminated more reliably.

  In the above embodiment, the plurality of elongated electrode portions 41 of the pixel electrode 4 are commonly connected at one end (the end portion on the side connected to the TFT 6). You may connect in common at the both ends.

  In the above embodiment, the counter electrode 5 is formed in a shape corresponding to the entire area of the pixel 100, but the counter electrode 5 is interposed between at least the plurality of elongated electrode portions 41, 41 of the pixel electrode 4. It only needs to be compatible.

  Further, in the liquid crystal display element of the above embodiment, the first electrode on the liquid crystal layer 3 side of the first and second electrodes provided on the inner surface of the rear substrate 2 is arranged in a matrix. The plurality of pixel electrodes 4 and the second electrode on the rear substrate 2 side as the counter electrode 5 are used as the counter electrode 5, but conversely, the first electrode on the liquid crystal layer 3 side is used as the counter electrode and the back side thereof. The second electrode on the substrate 2 side may be a plurality of pixel electrodes arranged in a matrix. In that case, a plurality of elongated electrode portions are formed on the counter electrode, and the pixel electrode is applied to the entire area of the pixel. Or a shape corresponding to between the plurality of elongated electrode portions of the counter electrode.

  In the above embodiment, the first and second electrodes are provided on the inner surface of the rear substrate 2. However, the first and second electrodes may be provided on the inner surface of the front substrate 1.

The top view of a part of one board | substrate of the liquid crystal display element which shows one Example of this invention. Sectional drawing which follows the II-II line | wire of FIG. 1 of the said liquid crystal display element. FIG. 3 is an enlarged plan view of a part of a pixel electrode and a counter electrode of the liquid crystal display element. The enlarged plan view of one elongate electrode part of the said pixel electrode. The top view which shows direction of the molecular long axis of the liquid crystal molecule of each part in one pixel when a horizontal electric field is produced | generated between the said pixel electrode and a counter electrode. The expanded sectional view which abbreviate | omitted hatching along the VI-VI line of FIG. The expanded sectional view which abbreviate | omitted hatching along the VII-VII line of FIG. In a comparative example in which a liquid crystal layer made of nematic liquid crystal having positive dielectric anisotropy is sealed between substrates, liquid crystal molecules in each part in one pixel when a horizontal electric field is generated between the pixel electrode and the counter electrode The top view which shows direction of a molecular long axis. The expanded sectional view which abbreviate | omitted hatching along the IX-IX line of FIG. The expanded sectional view which abbreviate | omitted hatching along the XX line of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 2 ... Substrate, 1a, 1b ... Orientation process direction, 3 ... Liquid crystal layer, 3a ... Liquid crystal molecule, 4 ... Pixel electrode, 41 ... Elongate electrode part, 42a, 42b ... Elongated side part, 5 ... Counter electrode, 6 ... TFT (active element), 12 ... scanning line, 13 ... signal line, 14 ... interlayer insulating film, 15 ... light shielding film, 16R, 16G, 16B ... color filter, 17, 18 ... alignment film, 19, 20 ... polarizing plate, 21 ... Electrostatic shielding conductive film, 100 ... Pixel, E ... Lateral electric field.

Claims (2)

A pair of substrates that are arranged opposite to each other with a predetermined gap, and each of the inner surfaces facing each other is subjected to alignment treatment in parallel and in opposite directions;
The nematic liquid crystal is sealed in the gap between the pair of substrates and has negative dielectric anisotropy, and the liquid crystal molecules are aligned substantially parallel to the substrate surface with the molecular long axes aligned with the alignment treatment direction. Liquid crystal layer,
A plurality of elongated electrode portions are arranged in parallel in a predetermined unit region for forming one pixel, which is provided on the inner surface of one of the pair of substrates facing each other. A first electrode formed in a shape intersecting each other at one end of two elongated side portions that are formed and each of the plurality of elongated electrode portions extends at a different angle with respect to the direction of the alignment treatment;
The first electrode on the inner surface of one substrate is disposed closer to the first substrate than the first electrode, and the first electrode is applied by applying a voltage between the first electrode and the first electrode. A second electrode that generates a transverse electric field that changes the direction of the molecular major axis of the liquid crystal molecules in a direction substantially parallel to the substrate surface between the plurality of elongated electrode portions of the electrode;
A liquid crystal display element comprising: When the inclination angle with respect to the orientation treatment direction of the two elongated sides of the plurality of elongated electrode portions of the first electrode is θ, the inclination angle θ is
70 ° <θ <90 °
The liquid crystal display element according to claim 1, wherein the liquid crystal display element is set as follows.

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