JP2006106101A - Liquid crystal display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an MVA (multi-domain vertically aligned) mode transmissive or transflective liquid crystal display device in which disclination is suppressed and of which the display quality is excellent. <P>SOLUTION: In a liquid crystal display panel 10 having: a first substrate which has a transmissive section constructed with a pixel electrode 15 with a slit 17 formed on each position partitioned with signal lines 14 and scanning lines 13 arranged in a matrix; a second substrate on which a color filter, a common electrode and a protrusion 23 are formed; alignment layers laminated on both substrates and subjected to vertical alignment treatment; and a liquid crystal layer with negative dielectric anisotropy disposed between both substrates, wherein the liquid crystal molecules are vertically aligned in the case no electric field is applied to the liquid crystal layer, and the liquid crystal molecules are inclined toward a direction controlled by the slits and the protrusions and aligned in the case an electric field is applied to the liquid crystal layer, the slit 17 is arranged on the center part of the pixel electrode 15 and the protrusion 23 is arranged so as to surround the periphery of the pixel electrode 15. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display panel, and more particularly to an MVA (Multi-domain Vertically Aligned) type transmissive or transflective liquid crystal display panel in which disclination is suppressed and display quality is good.

  In general, liquid crystal display devices are characterized by thinness, light weight and low power consumption. In particular, TFT (Thin Film Transistor) type liquid crystal display devices are widely used from portable terminals to large-sized televisions. As a liquid crystal display panel used in this liquid crystal display device, a VA (vertically aligned) liquid crystal display panel is widely known as a liquid crystal display system having a quick response while maintaining a wide viewing angle.

  In the VA liquid crystal display panel 60, as shown in FIG. 7, a liquid crystal having a negative dielectric anisotropy is sealed between a pair of substrates 62 and 64, and one substrate 62 has a pixel electrode 61, A common electrode 63 is disposed on the other substrate 64. When the alignment films 66 and 67 on both the substrates 62 and 64 are both subjected to the vertical alignment process, and no electric field is applied to the electrodes 61 and 63, the liquid crystal molecules 65 are vertically aligned as shown in FIG. Are arranged. Polarizing plates 68 and 69 are arranged in crossed Nicols on the outer sides of both substrates 62 and 64. When no electric field is applied between the electrodes 61 and 63, the liquid crystal molecules 65 between the substrates are arranged vertically, so that the linearly polarized transmitted light that has passed through one polarizing plate passes through the liquid crystal layer as it is. The other polarizing plate blocks the dark state, that is, black display. When an electric field is applied between the electrodes 61 and 63, as shown in FIG. 7B, the liquid crystal molecules 65 between the substrates are arranged horizontally, so that the linearly polarized light transmitted through one polarizing plate is transmitted. When the light passes through the liquid crystal layer, it is birefringent to become elliptically polarized light, passes through the other polarizing plate, and becomes a bright state, that is, white display.

  In this VA mode liquid crystal display panel, when no electric field is applied between the electrodes 61 and 63, all the liquid crystal molecules 65 are aligned vertically on the alignment films 66 and 67, but an electric field is applied. In some cases, the direction in which each liquid crystal molecule 65 is tilted in the horizontal direction cannot be controlled, so that the liquid crystal molecules 65 are tilted in a random direction and are horizontally aligned as they are, and display unevenness is conspicuous. There has been a problem that the alignment of liquid crystal molecules is disturbed and disclination occurs.

  To regulate the direction in which the liquid crystal molecules standing vertically when an electric field is applied between the electrodes is tilted to achieve a uniform display state, the liquid crystal molecules are completely vertical when no electric field is applied between the electrodes. Instead, it is necessary to make it stand at a slight angle from the vertical axis, that is, the pretilt angle, and the distribution state in the tilt direction must be substantially equal for each pixel.

In order to further improve the viewing angle of the VA liquid crystal display panel, an MVA (Multi-domain vertically aligned) method is proposed in which a plurality of domains are formed in one pixel by providing protrusions and grooves in the pixel. (See Patent Documents 1 and 2 below)
The pixel configuration of this conventional MVA liquid crystal display panel will be described with reference to FIGS. 8 is a plan view of a pixel of a conventional MVA liquid crystal display panel 70, and FIG. 9 is a cross-sectional view taken along the line CC of FIG.

  On a transparent first substrate 71 such as a glass substrate, scanning lines 72 and signal lines 73 are arranged in a matrix via a gate insulating film 71 '. A region surrounded by the scanning line 72 and the signal line 73 corresponds to one pixel, a pixel electrode 74 is disposed in this region, and a switching element connected to the pixel electrode 74 is disposed at the intersection of the scanning line 72 and the signal line 73. A certain TFT 75 is formed. A part of the pixel electrode 74 overlaps the adjacent scanning line 72 with an insulating film 71 ″ interposed therebetween, and this part functions as a storage capacitor. A plurality of slits 76 to be described later are formed in the pixel electrode 74. The alignment film 77 covering the electrode 74 is subjected to a vertical alignment process.

  On a transparent second substrate 78 such as a glass substrate, a black matrix 79 is formed so as to divide each pixel, and a color filter 80 is laminated corresponding to each pixel. The color filter 80 is provided with one color filter 80 of red (R), green (G), and blue (B) corresponding to each pixel. A common electrode 81 made of a transparent electrode such as ITO is laminated on the color filter 80. A projection 82 having a predetermined pattern is formed on the common electrode 81, and the common electrode 81 and the projection 82 are subjected to a vertical alignment process. The alignment film 83 is covered.

  A liquid crystal layer 84 having a negative dielectric anisotropy is interposed between the substrates 71 and 78. When no electric field is generated between the pixel electrode 74 and the common electrode 81, the liquid crystal molecules 84 ′ are vertically aligned by being regulated by the alignment films 77 and 83, and an electric field is generated between the pixel electrode 74 and the common electrode 81. The liquid crystal molecules 84 'are inclined in the horizontal direction. At this time, the liquid crystal molecules 84 ′ are regulated by the slits 76 and the protrusions 82 and tilted in a predetermined direction, so that a plurality of domains can be formed in one pixel. FIG. 9 schematically shows a state where an electric field is generated between the pixel electrode 74 and the common electrode 81.

  A first polarizing plate 85 is disposed outside the first substrate 71, and a second polarizing plate 86 is disposed outside the second substrate 78, and the first polarizing plate 85 and the second polarizing plate 86 have their respective transmission axes. It is set to be orthogonal. The direction of both polarizing plates 85 and 86 is set by the relationship between the transmission axis and the direction of the liquid crystal molecules 84 ′ when tilted, but the transmission axis of the polarizing plates 85 and 86 and the direction of inclination of the liquid crystal molecules 84 ′ Since the relationship will be described later, here, for the sake of convenience, the transmission axis of the first polarizing plate 85 coincides with the extending direction of the scanning line 72, and the transmission axis of the second polarizing plate 86 coincides with the extending direction of the signal line 73. Set as follows.

  When no electric field is generated between the pixel electrode 74 and the common electrode 81, the liquid crystal molecules 84 'are aligned vertically, so that the linearly polarized transmitted light that has passed through the first polarizing plate 85 passes through the liquid crystal layer 84 as linearly polarized light. Then, it is blocked by the second polarizing plate 86 and a black display is obtained. In addition, when a predetermined voltage is applied to the pixel electrode 74 and an electric field is generated between the pixel electrode 74 and the common electrode 81, the liquid crystal molecules 84 ′ are inclined in the horizontal direction. The transmitted light becomes elliptically polarized light in the liquid crystal layer 84, passes through the second polarizing plate 86, and becomes white display.

  Next, the shapes of the slits 76 and the protrusions 82 will be described. The slit 76 is formed by removing a part of the pixel electrode 74 by a photolithography method or the like, and the protrusion 82 is formed in a predetermined pattern by using a resist made of, for example, an acrylic resin or the like by a photolithography method.

  The protrusions 82 are formed in a zigzag shape across a plurality of pixels, and the straight portions extend in a direction of 45 ° with respect to the signal lines 73 when viewed from the normal direction of the second substrate 78. In a substantially central portion of one pixel, a protrusion 82a extending from one adjacent pixel bends 90 ° and extends to an adjacent pixel again, and a protrusion 82b extending from the other adjacent pixel is a straight portion of the protrusion 82a bent at a right angle. And is located near the corner of the pixel.

  The slits 76 are formed so as to be respectively located in the middle of the plurality of protrusions 82. In this example, as shown in FIG. 8, three slits 76 are formed in each pixel electrode 74. A slit 76 a is formed between the protrusion 82 a and the protrusion 82 b, and a slit 76 b is formed between the protrusion 82 a and the edge portion of the pixel electrode 74. The slit 76 a has a center line parallel to the adjacent protrusion 82 and is at a 45 ° direction with respect to the signal line 73. The center line of the slit 76a corresponds to the extending direction of the slit 76a. Similarly, the extending direction of the slit 76b is parallel to the adjacent protrusion 82a. Since the extending direction of the protrusion 82a adjacent to the slit 76b is bent at a right angle within the pixel, the extending direction of the slit 76b is also bent.

  The liquid crystal molecules 84 ′ are inclined in the 90 ° direction with respect to the protrusions 82 and the slits 76, and are inclined in the opposite direction with respect to the protrusions 82 and the slits 76. A pair of crossed Nicols polarizers are arranged outside the pair of glass substrates, the angle between the transmission axis of the polarizer and the direction of the projection 82 is set to 45 °, and the normal direction of the polarizer The angle between the tilted liquid crystal molecules and the transmission axis of the polarizing plate is 45 °. When the angle between the tilted liquid crystal molecules and the transmission axis of the polarizing plate is 45 °, the transmitted light can be most efficiently obtained from the polarizing plate.

  This MVA liquid crystal display panel has the advantage that alignment film is not required to be rubbed and alignment division can be achieved by arranging linear structures. Therefore, the MVA liquid crystal display panel can obtain a wide viewing angle and high contrast. Further, since it is not necessary to perform rubbing, the manufacture of the liquid crystal display panel is simple, and there is no contamination due to shaving of the alignment film during rubbing, and the reliability of the liquid crystal display panel is improved.

  However, in the conventional MVA liquid crystal display panel, the actual display state of the liquid crystal molecules is not ideal, and thus an optimal display state cannot be obtained. In particular, in the peripheral portion of the pixel electrode 74, when the liquid crystal molecules 84 'are tilted, not only the protrusion 82 and the slit 76 but also the edge portion of the pixel electrode 74 is affected, so that display unevenness is likely to occur.

  FIG. 10 schematically shows the tilted state of the liquid crystal molecules. The arrow in the pixel electrode 74 indicates the tilt direction of the liquid crystal molecules, and the direction of the arrow is from the end close to the glass substrate having the protrusions 82 to the glass substrate having the pixel electrode 74 when the liquid crystal molecules are tilted. The direction toward the near end is shown.

  The liquid crystal molecules 84 ′ are regulated so as to incline in the direction of about 90 ° with respect to the protrusions 82 and the slits 76. The contour portions of the protrusion 82 and the slit 76 facing each other are in the same direction. The edge portion of the pixel electrode 74 affects the liquid crystal molecules to be inclined in the 90 ° direction, and the edge portion is not parallel to the slits 76 and the protrusions 82, so that the inclined state of the liquid crystal molecules 84 'is adversely affected. The influence of the edge portion is greatly different depending on the arrangement positional relationship between the slit 76 and the protrusion 82 near the edge portion. For example, in the area A1 in FIG. 10, the direction of the arrow near the slit 76 and the protrusion 82 is deviated by about 45 ° from the direction of the arrow near the edge, but in the area A2, the direction of the arrow near the slit 76 and the protrusion 82 is changed. The direction of the arrow in the vicinity of the edge portion is shifted by about 135 °, and the tilted state of the liquid crystal molecules is greatly disturbed in the region A2. Therefore, display unevenness is more likely to occur in the area A2 than in the area A1.

  As described above, in the conventional MVA type liquid crystal display panel, the alignment of the liquid crystal molecules 84 ′ is disturbed due to the presence of the edge portion of the pixel electrode 74 in the peripheral portion of one pixel in the pretilt direction, and the peripheral portion thereof. However, there was a problem that disclination occurred.

  In order to solve the problem peculiar to the MVA liquid crystal display panel (occurrence of misalignment region), a new structure is proposed in Patent Document 2 below. Hereinafter, an MVA type liquid crystal display panel 90 disclosed in the following Patent Document 2 will be described with reference to FIGS. 11 and 12, and the same configuration as the MVA type liquid crystal display panel 70 shown in FIGS. The same reference numerals are assigned to the portions, and detailed description of the portions is omitted. 11 is a plan view of a pixel of an MVA liquid crystal display panel disclosed in Patent Document 2 below, and FIG. 12 is a cross-sectional view taken along the line DD in FIG. FIG. 12A shows a state before an electric field is applied, and FIG. 12B shows a state after the electric field is applied.

  The MVA liquid crystal display panel 90 as shown in FIGS. 11 and 12 is different from the MVA liquid crystal display panel 70 shown in FIGS. 8 and 9 in order to control the alignment of liquid crystal molecules. This is that an auxiliary projection 89 is provided on the projection 82 outside the effective pixel range, and the other configuration is substantially the same as the configuration of the MVA liquid crystal display panel 70 shown in FIGS. According to the MVA-type liquid crystal display panel 90, the influence of the electric field from the edge portion of the pixel electrode 74 and the adjacent pixel on the liquid crystal molecules 84 ′ is reduced, and the generation of disclination can be effectively suppressed. It can be done.

In portable devices that use liquid crystal display panels, transflective liquid crystal display panels having both transmissive and reflective properties have been developed to reduce power consumption. In such a transflective liquid crystal display panel, the application of the MVA method as described above can be seen, and in Patent Document 3 below, in the transflective liquid crystal display device, the reflective portion on the color filter side and In addition to providing slits in the common electrode of the transmissive part, and an alignment means for dividing the orientation of liquid crystal molecules in the vicinity of the pixel electrode of the reflective part and the pixel electrode of the transmissive part, an open area or a convex body is disclosed. ing.
JP-A-11-024225 (Claims, FIGS. 10 to 12) JP 2001-083517 A (paragraphs [0007] to [0037), FIGS. 32 to 34) JP 2004-069767 A (claims, paragraphs [0043] to [0078], FIGS. 1 to 14)

However, in the MVA liquid crystal display panel configured as described above,
(1) Due to the difference in level difference, the position where the projection is formed, the variation in the shape of the projection, and the like, the positional relationship between the pixel electrode and the auxiliary projection is inevitably shifted in manufacturing, and this causes uneven brightness. There is,
(2) In the liquid crystal display panel, spherical spacers are dispersed to form a cell gap, and when this spherical spacer is placed on the auxiliary protrusion, the cell gap becomes particularly large in this portion, and
(3) Since the protrusion is provided on the pixel electrode, even when no voltage is applied, the protrusion causes the liquid crystal molecules to be slightly inclined due to the inclination of the protrusion (not perfectly vertically aligned), so that light leaks and the contrast decreases. To
There is a problem that
Further, in the transflective liquid crystal display panel as described above, the same problems as in the above (3) occur, and when no projection is provided, the orientation of the liquid crystal molecules is controlled by the slit or the opening region. Therefore, there is a problem that the alignment control effect of liquid crystal molecules is weak.

  In addition, not only large liquid crystal display panels but also small (about 2 inches for portable use) demand for image quality is higher than before, with a wider viewing angle, higher contrast, etc. than STN and TN methods. Since the MVA system which is provided with the features has been introduced, it is an urgent need to solve the above-mentioned problems of the MVA liquid crystal display panel.

  The inventors of the present invention have a problem with the above-described MVA liquid crystal display panel that the protrusions are provided in a zigzag shape on the common electrode at a position facing the pixel electrode, and the disadvantages of the zigzag protrusions. This is caused by providing auxiliary projections on the pixel electrode side in order to improve the above. Similarly, when providing projections in the above-described transflective liquid crystal display panel, projections are arranged on the surface of the pixel electrodes. Therefore, if there are no protrusions on the surface of the pixel electrode or the surface of the common electrode at the position facing the pixel electrode, all these problems should be solved, and the configuration for that As a result of various experiments, a slit was provided in the center of the pixel electrode in the transmissive part, and a protrusion was provided on the surface of the common electrode facing the pixel electrode so as to surround the pixel electrode in the transmissive part. Found that it is possible to solve all the above problems by, it was accomplished the present invention.

  That is, an object of the present invention is to provide an MVA-type transmissive or transflective liquid crystal display panel that generates less disclination, has less display unevenness and brightness unevenness, and is bright and has good display quality. .

  The above object of the present invention can be achieved by the following configurations. That is, the invention of the liquid crystal display panel according to claim 1 includes a first substrate on which a transmission portion including a pixel electrode having a slit is formed at each position partitioned by signal lines and scanning lines arranged in a matrix. , A second substrate on which a color filter, a common electrode and a protrusion are formed, an alignment film subjected to a vertical alignment process laminated on both the substrates, and a negative dielectric anisotropy disposed between the two substrates. A liquid crystal layer, and when no electric field is applied to the liquid crystal layer, the liquid crystal molecules are aligned vertically, and when an electric field is applied to the liquid crystal layer, the liquid crystal molecules are inclined in a direction regulated by the slits and the protrusions. In the liquid crystal display panel, the slit is provided at the center of the pixel electrode, and the protrusion is provided so as to surround the pixel electrode.

  The “center portion” in the present invention means a state where the slit does not have a portion reaching the end portion of the pixel electrode and the periphery of the slit is surrounded by the pixel electrode.

  According to a second aspect of the present invention, in the liquid crystal display panel according to the first aspect, the slit has a rectangular shape with a gentle corner extending in parallel with the extending direction of the pixel electrode. The center part of a square-shaped slit is provided with the several protrusion part which goes to the said slit side, It is characterized by the above-mentioned.

  According to a third aspect of the present invention, in the liquid crystal display panel according to the first aspect, the slit is long in the extending direction of the pixel electrode, and each tip has a gentle cross shape. .

  According to a fourth aspect of the present invention, in the liquid crystal display panel according to any one of the first to third aspects, a reflecting portion is also formed at each position partitioned by the signal lines and the scanning lines arranged in the matrix form. It is characterized by being. In this case, the liquid crystal display panel is a transflective liquid crystal display panel.

  According to a fifth aspect of the present invention, in the liquid crystal display panel according to the fourth aspect, a colorless portion is provided at the center of the color filter facing the reflection portion.

  By providing the above configuration, the present invention has the following excellent effects. That is, according to the first aspect of the present invention, since there is no protrusion in the transmissive portion, a part of the light transmitted through the pixel electrode is not absorbed by the protrusion, so that a bright liquid crystal display panel can be obtained. Moreover, due to the arrangement relationship between the protrusions and the slits, the alignment direction of the liquid crystal molecules extends over 360 °, so that there is little generation of disclination, display unevenness and brightness unevenness, and MVA liquid crystal with good display quality. A display panel is obtained.

  According to the invention of claim 2, the alignment direction of the liquid crystal molecules changes smoothly and continuously at the end of the slit, but when the length of the slit becomes longer, the alignment at the intermediate portion in the length direction of the slit Although the regulation is weakened and disclination is likely to occur, since the protruding portion of the protrusion extends in this portion, the generation of disclination is reduced.

  Further, according to the invention of claim 3, contrary to the invention of claim 2, since the lateral portion of the cross-shaped slit extends in the middle portion of the slit in the longitudinal direction, the generation of disclination is similarly performed. Less.

  Further, according to the invention of claim 4, since the liquid crystal properties required in the reflective portion have the same properties as the liquid crystal used in the MVA liquid crystal display panel, the transmissive portion has the characteristics of the MVA mode. The transflective liquid crystal display panel provided is obtained.

According to the invention of claim 5, since the effect of the color filter of the reflection part can be adjusted by the colorless part of the color filter of the reflection part, the thickness of the color filter of the reflection part is made the same as the thickness of the transmission part. However, it is possible to easily make the color tone of the reflecting portion and the transmitting portion the same.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments shown below show embodiments of a transmissive or transflective liquid crystal display panel for embodying the technical idea of the present invention. However, it is not intended that the present invention be limited to that described herein. In addition, the liquid crystal display panel shown in the embodiment is a small liquid crystal display panel mainly used in a display unit for a mobile device such as a digital camera or a mobile phone, and has a resolution of more than 300 ppi. It shows a panel with about 640 × 480 pixels (VGA) and 320 × 240 pixels (QVGA), and the size of one pixel is considerably smaller than a liquid crystal display panel for TVs such as 40 inches. It has become a thing.

  A transmissive liquid crystal display panel according to Example 1 is shown in FIGS. FIG. 1 is a schematic plan view showing one pixel portion of a transmissive liquid crystal display panel seen through a color filter, and FIG. 2 is a cross-sectional view taken along line AA of FIG.

  1 and 2, a transmissive liquid crystal display panel 10 includes scanning lines 13 and signal lines 14 arranged in a matrix on a transparent first substrate 11 such as a glass substrate with a gate insulating film 12 interposed therebetween. . A region surrounded by the scanning line 13 and the signal line 14 corresponds to one pixel, and a pixel electrode 15 made of a transparent conductive material such as ITO is disposed in this region, and at the intersection of the scanning line 13 and the signal line 14. A TFT 16 serving as a switching element connected to the pixel electrode 15 is formed.

  A slit 17 described later is formed in the vicinity of the center of the area where the light of the pixel electrode 15 can be transmitted. The alignment film 18 that covers the pixel electrode 16 is subjected to a vertical alignment process.

  A black matrix 20 is formed on a transparent second substrate 19 such as a glass substrate so as to divide each pixel, and a color filter 21 is laminated corresponding to each pixel. The color filter 21 is provided with one color filter 21 of red (R), green (G), and blue (B) corresponding to each pixel. A common electrode 22 made of a transparent electrode such as ITO is laminated on the color filter 21, and a projection 23 having a predetermined pattern is formed on the common electrode 22. The common electrode 22 and the projection 23 are subjected to a vertical alignment process. Covered with an alignment film 24.

  A liquid crystal layer 25 having a negative dielectric anisotropy is interposed between the substrates 11 and 19. When no electric field is generated between the pixel electrode 15 and the common electrode 22, the liquid crystal molecules are regulated vertically by the alignment films 18 and 24, and when an electric field is generated between the pixel electrode 15 and the common electrode 22, the liquid crystal is aligned. Molecules tilt horizontally. At this time, the liquid crystal molecules are regulated by the slits 17 and the protrusions 23 and tilted in a predetermined direction, so that a plurality of domains can be formed in one pixel.

  A first polarizing plate and a second polarizing plate (both not shown) are arranged outside the first substrate 11 and outside the second substrate 19, respectively, so that their transmission axes are orthogonal to each other. Is set to The orientation of both polarizing plates is set by the relationship between the transmission axis and the orientation of the liquid crystal molecules when tilted, but the relationship between the transmission axis of the polarizing plate and the tilting direction of the liquid crystal molecules will be described later. The transmission axis of the first polarizing plate coincides with the extending direction of the scanning line 13 and the transmission axis of the second polarizing plate coincides with the extending direction of the signal line 14.

  When no electric field is generated between the pixel electrode 15 and the common electrode 22, the liquid crystal molecules are aligned vertically, so that the linearly polarized transmitted light that has passed through the first polarizing plate passes through the liquid crystal layer 25 as linearly polarized light. It is blocked by the second polarizing plate and becomes black. In addition, when a predetermined voltage is applied to the pixel electrode 15 and an electric field is generated between the pixel electrode 15 and the common electrode 22, the liquid crystal molecules are inclined in the horizontal direction. Becomes elliptically polarized light in the liquid crystal layer 25, passes through the second polarizing plate, and becomes white display.

  Next, the shape of the slit 17 and the protrusion 23 will be described. The slit 17 is formed by removing a part of the pixel electrode 15 by a photolithography method or the like, and the protrusion 23 is formed in a predetermined pattern by using a resist made of, for example, an acrylic resin or the like by a photolithography method.

  The protrusions 23 are provided so as to surround the effective transmission region of the rectangular pixel electrode 15, and in FIG. 1, the portions corresponding to the three sides of the rectangular ring are provided so as to face the scanning lines 13 and the signal lines 14. However, the four sides may be provided so as to face the scanning line 13 and the signal line 14.

  Here, the term “square ring” of the protrusion 23 is a shape that can be seen when only one pixel portion is viewed, and in FIG. 1, as indicated by a dotted line 23 ′, it is adjacent to at least the left and right. It is formed continuously over the pixel portion. In the pixel adjacent to the pixel on which the protrusion 23 is formed, the dotted line 23 ′ is described on the inner side. In practice, however, the boundary between the protrusion 23 and the dotted line 23 ′ is located on the signal line 14. preferable. Further, from the viewpoint of preventing a decrease in luminance, the width of the protrusion 23 is preferably within the width of the signal line 14 and is large enough not to protrude from the signal line in plan view. Moreover, even if it says a ring, it does not have to be completely continuous. For example, when applying an alignment film, in order to prevent the alignment film from accumulating in the ring, the alignment film accumulates in the ring by cutting several small portions. You may make it prevent.

  The slit 17 is formed at substantially the center of the pixel electrode 15 so as to be located in the middle of the protrusion 23, and the slit 17 does not reach the scanning line 13 or the signal line 14. In this example, it is a cross shape, and the pixel electrode 15 is thick and long in the extending direction 17a, thin and short in the perpendicular direction 17b, and each tip has a gentle curved shape.

  According to the transmissive liquid crystal display panel having such a configuration, since there is substantially no projection in the portion facing the pixel electrode 15, that is, in the transmissive portion, part of the light transmitted through the pixel electrode 15 is caused by the projection 23. Since it is not absorbed, a bright liquid crystal display panel 10 is obtained. Moreover, because of the arrangement relationship between the protrusions 23 and the slits 17, the alignment direction of the liquid crystal molecules extends over 360 °, so that there is little generation of disclination, less display unevenness and brightness unevenness, and good display quality. The liquid crystal display panel 10 is obtained.

  In the first embodiment, the shape of the slit is not limited to the shape shown in FIG. 1, but is a cross shape as shown in FIG. It is possible to adopt a thin and long shape in the present direction 17a, a thick and short shape in the perpendicular direction 17b, and each tip portion having a gentle curved shape, or a pixel electrode 15 as shown in FIG. The corner portion extending in parallel with the extending direction of the pixel electrode may have a gentle square shape, and the protrusion may include a plurality of protruding portions 23a toward the slit side at the central portion in the extending direction of the pixel electrode. . In other words, when the slit length is increased, the orientation restriction at the intermediate portion in the slit length direction is weakened and disclination is likely to occur. Not only the direction portion but also a plurality of projecting portions toward the slit side can be compensated for in the central portion in the extending direction of the pixel electrode.

  A transflective liquid crystal display device 10A according to Example 2 is shown in FIGS. 4 is a schematic plan view showing one pixel portion of the transflective liquid crystal display panel through a color filter, and FIG. 5 is a cross-sectional view taken along the line BB in FIG. In FIGS. 4 and 5, the same components as those of the transmissive liquid crystal display device 10 shown in FIGS. 1 and 2 are given the same reference numerals for explanation.

  4 and 5, the transflective liquid crystal display panel 10A includes a scanning line 13 and signal lines 14 arranged in a matrix on a transparent first substrate 11 such as a glass substrate with a gate insulating film 12 interposed therebetween. Yes. A region surrounded by the scanning line 13 and the signal line 14 corresponds to one pixel, and the pixel electrode 15 is disposed in this region. This pixel is divided into a reflection part and a transmission part at an intermediate part, and a slit 17 which will be described later is formed at the center of the pixel electrode 15 of the transmission part. A TFT 16 which is a switching element connected to the pixel electrode 15 is formed at the intersection of the scanning line 13 and the signal line 14.

  The gate electrode G of the TFT 16 is connected to the scanning line 13, the source electrode S is connected to the signal line 14, and the drain electrode D is formed above the auxiliary capacitance electrode 31 formed on the first substrate 11. It extends through. A transparent insulating film 32 and an interlayer insulating film 33 are provided over the entire surface of the FET 16 and the surface of the gate insulating film 12, and the surfaces are flattened to make the cell gap constant. Note that the surface of the interlayer insulating film 33 located in the reflecting portion is slightly uneven in order to obtain diffusely reflected light with no directivity, and the surface of the interlayer insulating film 33 in the reflecting portion is Is provided with a reflective electrode 34 made of a highly reflective metal such as silver or aluminum, and a pixel electrode made of a transparent conductive member such as ITO on the surface of the reflective electrode 34 and the surface of the interlayer film 33 in the transmissive portion. 15 is provided. The surface of the pixel electrode 15 and the slit 17 are covered with an alignment film 18 subjected to a vertical alignment process. Note that the pixel electrode 15 in the reflective portion and the drain electrode D of the TFT 16 are electrically connected by a contact hole 35.

  A black matrix (not shown) is formed on the transparent second substrate 19 such as a glass substrate so as to divide each pixel, and a color filter 21 is laminated corresponding to each pixel. The color filter 21 is provided with one color filter 21 of red (R), green (G), and blue (B) corresponding to each pixel. A common electrode 22 made of a transparent electrode such as ITO is laminated on the color filter 21, and a projection 23 having a predetermined pattern is formed on the common electrode 22. The common electrode 22 and the projection 23 are subjected to a vertical alignment process. Covered with an alignment film 24.

  In the second embodiment, since the color filter 21 having the same thickness is used in the reflective portion and the transmissive portion, the cutout portion 36 in which the color filter is not present in a part of the color filter 22 in the reflective portion and the top coat having a predetermined thickness. 37 is provided. The top coat 37 is provided over the entire reflecting portion, and is held by a rib-like spacer 38 so as to form a predetermined cell gap. In addition, the notch 36 is provided so that the incident light passes through the color filter twice at the time of incidence and at the time of emission at the reflection part, so that a part with no color is provided and the color tone is the same as that of the transmission part. It is what.

  Further, a liquid crystal layer 25 having a negative dielectric anisotropy is interposed between the substrates 11 and 19. When no electric field is generated between the pixel electrode 15 and the common electrode 22, the liquid crystal molecules are regulated vertically by the alignment films 18 and 24, and when an electric field is generated between the pixel electrode 15 and the common electrode 22, the liquid crystal is aligned. Molecules tilt horizontally. At this time, the liquid crystal molecules in the transmission part are regulated by the slits 17 and the protrusions 23 and tilted in a predetermined direction, so that a plurality of domains can be formed in one pixel. Further, λ / 4 phase difference plates 39 and 40 are arranged outside the substrates 11 and 19, respectively.

  Next, the shape of the slit 17 and the protrusion 23 will be described. The slit 17 is formed by removing a part of the pixel electrode 15 by a photolithography method or the like, and the protrusion 23 is formed in a predetermined pattern by using a resist made of, for example, an acrylic resin or the like by a photolithography method.

The protrusion 23 is provided so as to surround the effective transmission region of the pixel electrode 15 of the rectangular transmission part, and in FIG. 4, the portions corresponding to the three sides of the rectangular ring are opposed to the scanning line 13 and the signal line 14. An example in which the other side is arranged along the top coat 37 of the reflecting portion is shown. The slit 17 is located at the center of the pixel electrode 15 of the transmissive portion so as to be located in the middle of the protrusion 23. In this example, it has a cross shape, and is thick and long in the extending direction 17a of the pixel electrode 15 of the transmissive portion, thin and short in the perpendicular direction 17b, and each tip has a gently curved shape. An example is shown.

  According to the transflective liquid crystal display panel 10A having such a configuration, since there is substantially no protrusion at the central portion facing the pixel electrode 15 in the transmissive part, one part of the light transmitted through the pixel electrode 15 in the transmissive part. The portion is no longer absorbed by the protrusion 23, and the orientation relationship between the protrusion 23 and the slit 17 extends the orientation direction of the liquid crystal molecules over 360 °. The MVA transflective liquid crystal display panel 10 with less luminance unevenness and good display quality of the transmissive part can be obtained.

  In the second embodiment, the shape of the slit is not limited to the shape shown in FIG. 4, but is a cross shape, for example, as shown in FIG. It is also possible to adopt a shape that is long and thin in the extending direction 17a, thick and short in the perpendicular direction 17b, and each tip portion having a gentle curved shape. Such a slit shape can ensure higher luminance than that of the first embodiment. Further, as shown in FIG. 3B, the corner portion extending in parallel with the extending direction of the pixel electrode 15 has a gentle square shape, and the protrusion is formed at the slit side in the center portion of the extending direction of the pixel electrode. It can also be provided with a plurality of projecting portions 23a facing. In other words, when the slit length is increased, the orientation restriction at the intermediate portion in the slit length direction is weakened and disclination is likely to occur. Not only the direction portion but also a plurality of projecting portions toward the slit side can be compensated for in the central portion in the extending direction of the pixel electrode.

  Further, the liquid crystal properties required in the reflection part are the same as the liquid crystal used in the MVA type liquid crystal display panel. When no electric field is generated between the pixel electrode 15 and the common electrode 22, the liquid crystal molecules are aligned. Since the liquid crystal molecules are inclined in the horizontal direction when an electric field is generated between the pixel electrode 15 and the common electrode 22, the liquid crystal molecules are inclined in the horizontal direction. By providing the orientation regulating means, it is possible to provide the features of the MVA method. At this time, for example, if the drain electrode and the auxiliary capacitance electrode 31 are sized so as to occupy most of the reflection portion in order to ensure a large auxiliary capacitance, the drain electrode has the same potential as the pixel electrode 15, so Even if a slit is provided in the electrode 15, it does not function as an orientation regulating means, and thus the liquid crystal can be aligned in a predetermined direction by providing the common electrode 22 with the protrusion 23. This example is shown in FIGS. 6C to 6F. Especially in the case of small liquid crystal panels, how to secure the size of the auxiliary capacity will become increasingly important in the future, so the shape of the above example is a high-definition liquid crystal display that is used especially for the display part of mobile devices. Suitable for panels.

  6 (c) and 6 (d), the slit 17 of the transmissive part has a square shape with a gentle corner that extends parallel to the extending direction of the pixel electrode 15, and the projection 23 of the transmissive part is a pixel electrode. 13 is provided with a plurality of projecting portions toward the slit side at the center in the extending direction, and the projection 41 of the reflecting portion is long in the extending direction of the pixel electrodes 15 having different thicknesses, and each tip portion is 6 (e) and 6 (f), the slits 17 of the transmission part are long in the extending direction of the pixel electrodes 15 having different thicknesses, and each tip has a gentle cross shape. The part has a gentle cross shape, and the projection 41 of the reflecting part has an X shape. In this case, since the protrusion 41 can be provided at the position of the notch 36 where the color filter of the reflection portion does not exist, the change in color tone in the reflection portion is small.

  In the transflective liquid crystal display devices described in FIG. 6C to FIG. 6F, since the alignment characteristics similar to those of the conventional MVA method can be provided in the reflection portion, there is little disclination. In addition, since the projections 41 in the reflecting portion do not affect the color tone, a transflective liquid crystal display panel with good display quality can be obtained.

FIG. 3 is a schematic plan view showing one pixel portion of a transmissive liquid crystal display panel according to the present invention through a color filter. It is sectional drawing along the AA line of FIG. FIG. 6 is a schematic plan view showing one pixel portion of another specific example of the transmissive liquid crystal display panel according to the present invention as seen through a color filter. FIG. 3 is a schematic plan view showing one pixel portion of a transflective liquid crystal display panel according to the present invention through a color filter. It is sectional drawing along the BB line of FIG. FIG. 6 is a schematic plan view showing one pixel portion of another specific example of the transflective liquid crystal display panel according to the present invention as seen through a color filter. It is a schematic plan view of a conventional VA liquid crystal display device. FIG. 10 is a plan view of a pixel of a conventional MVA liquid crystal display panel 70. It is sectional drawing along CC line of FIG. It is a figure which shows typically the inclination state of the liquid crystal molecule in the conventional MVA type liquid crystal display panel. It is a top view of the pixel of another conventional MVA-type liquid crystal display panel. FIGS. 12A and 12B are cross-sectional views taken along line D-D in FIG. 11. FIG. 12A shows a state before applying an electric field, and FIG. 12B shows a state after applying the electric field.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Transmission type liquid crystal display panel 10A Transflective type liquid crystal display panel 11 1st board | substrate 15 Pixel electrode 17 Slit 19 Second board | substrate 22 Common electrode 23, 41 Protrusion 24 Liquid crystal 31 Auxiliary capacity electrode 33 Interlayer insulation film 34 Reflective electrode 36 Notch 37 Topcoat 38 Spacer 39, 40 λ / 4 retardation plate

Claims (5)

  A first substrate on which a transmission part composed of pixel electrodes having slits is formed at respective positions partitioned by signal lines and scanning lines arranged in a matrix, and a second substrate on which color filters, common electrodes, and protrusions are formed And an alignment film that has been subjected to a vertical alignment process laminated on both substrates, and a liquid crystal layer having a negative dielectric anisotropy disposed between the substrates, and an electric field is applied to the liquid crystal layer The liquid crystal molecules are aligned vertically, and when an electric field is applied to the liquid crystal layer, in the liquid crystal display panel in which the liquid crystal molecules are inclined and arranged in a direction regulated by the slits and the protrusions, the slits are the pixel electrodes. A liquid crystal display panel, characterized in that the liquid crystal display panel is provided at a central portion, and the protrusion is provided so as to surround the periphery of the pixel electrode.   The slit has a rectangular shape with a gentle corner extending in parallel with the extending direction of the pixel electrode, and the protrusion has a plurality of projecting portions toward the slit at the center of the rectangular slit. The liquid crystal display panel according to claim 1.   The liquid crystal display panel according to claim 1, wherein the slit is long in the extending direction of the pixel electrode and has a gentle cross shape at the tip.   The liquid crystal display panel according to claim 1, wherein a reflection portion is also formed at each position partitioned by the signal lines and the scanning lines arranged in a matrix. The liquid crystal display panel according to claim 4, wherein a colorless portion is provided at a central portion of the color filter facing the reflection portion.

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