JP4830468B2 - LCD panel - Google Patents

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, and are widely used from portable terminals to large televisions. As a liquid crystal display panel used in this liquid crystal display device, a VA (vertically aligned) type is known.

  In the VA liquid crystal display panel 60, as shown in FIG. 4, 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, the liquid crystal molecules 65 between the substrates are arranged substantially horizontally as shown in FIG. When the transmitted 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, ie, white display.

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. . (Patent Document 1)
The pixel configuration of this conventional MVA liquid crystal display panel will be described with reference to FIGS. 5 is a plan view of a pixel of a conventional MVA liquid crystal display panel 70, and FIG. 6 is a cross-sectional view taken along line CC in 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 sub-pixels constituting each pixel, and a color filter 80 is laminated corresponding to each sub-pixel. The color filter 80 is provided with a color filter 80 of any one of red (R), green (G), and blue (B) corresponding to each sub-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. 6 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 sub-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 sub-pixel, a protrusion 82a extending from one adjacent sub-pixel is bent by 90 ° and extends again to an adjacent sub-pixel, and a protrusion 82b extending from the other adjacent sub-pixel is bent at a right angle. The protrusion 82a is disposed in parallel with the straight line portion and is located near the corner of the sub-pixel.

  The slits 76 are formed so as to be positioned respectively in the middle of the plurality of protrusions 82. In this example, as shown in FIG. 5, 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 sub-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.

  The liquid crystal display panel having such a structure is used as a large panel for a TV or a monitor particularly requiring a wide viewing angle.

  On the other hand, the demand for a wide viewing angle with respect to a liquid crystal display panel has not been so high since a user of a small display unit in a mobile device typified by a mobile phone is limited. However, recently, the demand for a wide viewing angle of a liquid crystal display panel in a display unit has been rapidly increasing in mobile devices with higher functionality.

  Based on the demand for wide viewing angle for such mobile devices, the TN liquid crystal display panel, which has been widely used for mobile devices, has been developed recently. .

  Especially for liquid crystal display panels used in mobile devices, transflective liquid crystal display panels that have both transmissive and reflective properties have been developed to reduce power consumption, assuming use outdoors and indoors. In such a transflective liquid crystal display panel as well, as disclosed in Patent Document 2, Patent Document 3, and the like, development of an MVA liquid crystal display panel is in progress.

  In the course of developing an MVA transflective liquid crystal display panel, the present inventors first tried the conventional zigzag projections and slits as shown in FIG. I noticed that it is not very suitable for small LCD panels.

  This seems to be due to the fact that the size of one pixel or the sub-pixels constituting it has become very small due to recent high definition even in a small liquid crystal display panel. As with small and medium-sized liquid crystal display panels made for monitors, zigzag projections and slits result in poor-looking liquid crystal display panels.

  Therefore, an attempt was made to chamfer the corner of the pixel electrode as shown in FIGS. 13B, 13D, 13F, and 13H of Patent Document 3.

  FIG. 7 shows a plan view of an example of a VA type transflective liquid crystal display panel with the corners of the pixel electrodes chamfered, and FIG. 8 shows a cross-sectional view taken along the line DD ′ of FIG. 5 and 6 are denoted by the same reference numerals, and description thereof is omitted.

  Reference numeral 74a denotes a pixel electrode formed in a so-called light transmission portion of the transflective display panel, which is formed of ITO or the like which is a transparent electrode material. The pixel electrode 74a is formed in substantially the entire region of the light transmission portion, but has an octagonal shape with the corner portions chamfered. The pixel electrode 74a chamfered in this way has a distance from the center of the pixel electrode 74a to the end of the pixel electrode 74b substantially the same in all directions.

  Reference numeral 74b denotes a pixel electrode formed in a so-called reflecting portion, which is formed simultaneously with ITO or the like, similarly to 74a. Reference numeral 74 ′ denotes a reflective electrode formed to reflect outside light at the reflecting portion. The reflective electrode 74 ′ is made of a metal material having a high reflectance such as Al. The reflective electrode 74 ′ is formed under the pixel electrode 74 b and is electrically connected to function as an electrode. However, the reflective electrode 74 ′ is not electrically connected to the pixel electrode 74 b and may not function as an electrode. What is necessary is just to have the function to reflect external light in a part.

  Reference numeral 82 'denotes a protrusion formed on the light transmission portion. Unlike the linear protrusion formed over the entire sub-pixel, this protrusion is a cross-shaped protrusion formed independently only on the light transmission portion. With the pixel electrode 74a having the chamfered projections 82 'and corner portions, the orientation of the liquid crystal molecules can be evenly regulated even in the light transmitting portion of a particularly small sub-pixel, and a wide-field VA liquid crystal display panel can be manufactured. .

82 ″ and projections formed on the reflection portion. This protrusion is not formed over the entire subpixel, but is an inverted Y-shaped protrusion formed independently only on the reflective portion. Note that 90 formed on the second substrate 78 is provided so that the distance of the external light passing through the reflecting portion and the distance of the light from the backlight passing through the light transmitting portion are substantially the same. There is a top coat. Reference numeral 91 denotes a contact hole. The drain electrode 75 ′ of the TFT 75 and the pixel electrode 74 b are electrically connected through the contact hole 91.
JP-A-11-024225 JP 2003-167253 A JP 2004-069767 A

  The contact hole 91 shown in FIGS. 7 and 8 has a certain size because it is necessary to ensure the electrical connection between the pixel electrode 74b and the drain electrode 75 ′.

  Further, in order to scatter and reflect external light at the normal reflection portion, the surface of the pixel electrode is made uneven. For example, the surface of the insulating film 71 ″ located below the pixel electrode 74 b is provided with unevenness by a photolithography method or the like. In particular, only the insulating film 71 ″ is shown in the figure, but a method of applying a thick organic film or the like made of an insulating material and providing unevenness on the surface is also employed.

  Therefore, the contact hole 91 has a certain size and depth. Such an inclination of the contact hole 91 gives a physical force to the liquid crystal molecules 84 ′ and tilts the liquid crystal molecules 84 ′. A cross-sectional view taken along line EE ′ of FIG. 7 is shown in FIG. 9 and conceptually shows the state.

  In particular, when a potential difference is generated between the pixel electrode 74 b and the common electrode 81 to align the liquid crystal molecules 84 ′, the liquid crystal molecules 84 ′ are strongly influenced by the physical force of the contact hole 91 and are directed in a desired direction. 84 'is not inclined, and the display quality is deteriorated by adversely affecting the display. In addition, since the contact hole 91 is literally a hole, the alignment is not easily illustrated due to the presence of the contact hole, such as unevenness in the alignment film (not shown), which eventually affects the display. And the display quality is degraded.

  In view of this, the present inventors, in an MVA liquid crystal display panel, have a high display quality, high quality MVA liquid crystal display in which deterioration of display quality due to the influence of a contact hole for conducting the drain electrode and the pixel electrode is suppressed. The purpose is to provide a panel. It is a further object of the present invention to provide an optimal liquid crystal display panel as a small panel.

In order to solve the above problems, the first substrate on which the switching element and the pixel electrode are formed at the respective positions partitioned by the signal lines and the scanning lines arranged in a matrix, and the protrusion for regulating the inclination of the liquid crystal molecules are common. a second substrate having electrodes formed, and an alignment film subjected to vertical alignment treatment, which is stacked on the two substrates, the liquid crystal display panel having a dielectric anisotropy disposed between the two substrates and a negative liquid crystal layer , when viewed in plan, are formed so as to butt force the contact hole for electrically connecting the electrode and the picture element electrodes of the switching elements are overlapped, the width of the protrusion is larger liquid crystal display panel than the contact hole is provided.

Furthermore, when viewed in plan, Rutoshite may be formed as reflection portion odor Te co contact hole and the protrusion overlap.

Furthermore, the impact force with overlaps in a U contact hole Te approximate center odor put that picture element electrode in the reflection portion, a collision force is that not extend from substantially the center of the picture element electrodes, especially on the collision force shape may be used as the inverted Y-shape.

According to the liquid crystal display panel according to the present invention, it is possible to suppress the deterioration of display quality by win suppress the inclination of the liquid crystal molecules by physical force of the contact hole. In particular, in a liquid crystal display panel provided with a reflecting portion that reflects external light, the position of the contact hole can be easily adjusted in the reflecting portion, and therefore, alignment with the protrusion can be easily performed.

  In addition, since the protrusion extends from the approximate center of the pixel electrode, liquid crystal molecules can be uniformly aligned, particularly in a small MVA liquid crystal panel.

  In addition, since a large auxiliary capacity can be secured in a small liquid crystal panel, the liquid crystal panel is suitable as a very small liquid crystal panel.

  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. And is not intended to limit the invention 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.

  1 and 2 show a transflective liquid crystal display panel according to an embodiment. FIG. 1 is a schematic plan view showing a portion of two continuous sub-pixels in a transflective liquid crystal display panel through a color filter, and FIG. 2 is taken along the line AA ′ of FIG. It is sectional drawing. Accordingly, one pixel is constituted by the three sub-pixels.

  1 and 2, the transflective liquid crystal display panel 10 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 subpixel, and a pixel electrode 15 made of a transparent conductive material such as ITO is formed in this region. The sub-pixel is divided into a reflection part and a light transmission part at an intermediate part, and the pixel electrode 15 is composed of a pixel electrode 15a existing in the light transmission part and a pixel electrode 15b existing in the reflection part. ing. Details of the shape and the like of the pixel electrode 15a will be described later.

  A reflective electrode 15b ′ is formed in the lower layer of the pixel electrode 15b as shown by the hatched portion in FIG. The reflective electrode 15b 'is formed to reflect external light at the reflective portion. Although shown in FIG. 1 smaller than the pixel electrode 15b, it has substantially the same size as the pixel electrode 15b. Since the region where the reflective electrode 15b ′ is present reflects external light, it becomes a reflective portion in one sub-pixel. The reflective electrode 15b 'is formed of a metal material having a high reflectance such as Al. The reflective electrode 15b ′ is electrically connected to the pixel electrode 15b and functions as an electrode. However, the reflective electrode 15b ′ is not necessarily electrically connected to the pixel electrode 15b and may not function as an electrode. In short, it is sufficient that the reflecting portion has a function of reflecting external light.

  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 TFT 16 includes a gate electrode G connected to the scanning line 13, a source electrode S connected to the signal line 14, a semiconductor such as amorphous silicon, a drain electrode D connected to the gate insulating film 12 and the pixel electrode 15b, and the like. Has been.

  The drain electrode D is formed to have a size that covers most of the reflective region in one subpixel. By forming such a large drain electrode D, a large auxiliary capacitance can be secured by forming the auxiliary capacitance line large when the auxiliary capacitance line is formed, although not shown.

  In particular, when a high-definition small-sized liquid crystal display panel is made, the size of one sub-pixel is very small, so that it is considered that the pixel capacitance formed between the pixel electrode and the common electrode is not sufficient for display. . Thus, it is important how to secure a large auxiliary capacity. By forming such a large drain electrode D, it is possible to ensure a large auxiliary capacity. For example, when the scanning line 13 is formed, the auxiliary capacitance line (not shown) may be formed in parallel and simultaneously on the same plane as the scanning line 13, and this structure is called a so-called Cs on common. Structure. Although not shown, the alignment film covering the pixel electrode 15 is subjected to a vertical alignment process.

  An insulating film layer 30 is formed on the gate insulating film 12 and the drain electrode D, and a contact hole 31 is formed in the insulating film layer 30. The pixel electrode 15 and the drain electrode D are conducted through the contact hole 31. In the embodiment, the insulating film layer 30 is a single layer, but another insulating film layer made of, for example, an organic material may be formed, and although not shown in the drawing, irregularities are formed on the surface of the insulating film layer, External light is scattered and reflected by making the reflective electrode 15 b ′ into an uneven shape.

  The contact hole 31 is formed at a position that is substantially the center of the drain electrode D that is largely formed in the reflection portion, and is also formed at the center of the reflection portion.

A black matrix (not shown) is formed on the transparent second substrate 19 such as a glass substrate so as to divide each subpixel, and a color filter 21 is laminated corresponding to each subpixel. The color filter 21 is provided with one color filter 21 of red (R), green (G), and blue (B) corresponding to each sub-pixel. Note that the structure of one pixel composed of sub-pixels is not intended to limit the present invention to the three colors R, G, and B as described above. For example, one pixel may be composed of four subpixels, or may be composed of five subpixels. In that case, depending on the number of sub-pixels, a color filter composed of R, G, B and other colors may be used, or a color filter composed of all other colors may be used.

  In the reflection portion, a layer called a so-called top coat 37 is formed on the color filter 21 in the reflection portion, and the distance of light passing through the liquid crystal layer 25 is adjusted to be substantially the same in the reflection portion and the light transmission portion. is doing.

  A common electrode 22 made of a transparent electrode such as ITO is laminated on the color filter 21 in the light transmission portion and on the top coat 37 in the reflection portion.

  A cross-shaped projection 23a is formed on the common electrode 22 in the light transmission portion, and an inverted Y-shaped projection 23b is formed on the common electrode 22 in the reflection portion. The common electrode 22 and the protrusions 23a and 23b are covered with an alignment film (not shown) that has been subjected to a vertical alignment process.

  In the small and high-definition liquid crystal panel as in the embodiment, both the protrusions 23a and 23b are present at least in the center of the light transmission part and the reflection part, and the liquid crystal molecules are centered on the center of the light transmission part and the reflection part. The orientation is regulated. If the orientation regulating means is formed at the center of the light transmission part and the reflection part in this way, it becomes easy to orient evenly in the entire area.

  Note that the projections 23a and 23b are not limited to the cross shape or the inverted Y shape as described above. For example, the circular shape is a square shape in the middle of each of the light transmitting portion and the reflecting portion. A protrusion may be formed. However, in a circular or quadrangular protrusion, the distance between the protrusion and the edge of the pixel electrode is not constant, and thus it is difficult to control the orientation uniformly in the entire region in the light transmission part and the reflection part. In particular, since the pixel electrode 15b and the reflective electrode 15b ′ are rectangular so as to reflect as much external light as possible at the reflective portion, the size of the protrusion 23b that simply overlaps the contact hole 31 is sufficient over the entire reflective portion. It is difficult to make the orientation uniform. Therefore, the protrusion 23b is preferably extended in various directions such as up, down, left and right from the approximate center of the pixel electrode. For example, an inverted Y shape as in this embodiment, or a Y shape, a cross shape, an X shape, etc. A shape extending from the center of the pixel electrode is preferable. Furthermore, considering that the alignment of the liquid crystal molecules is also controlled by the slit between the pixel electrode 15a and the pixel electrode 15b, the projection 23b is not necessary on the light transmission side, and the shape of the projection 23b is an inverted Y shape. Has been found to be a particularly preferred shape.

  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 inclined in a predetermined direction by the protrusions 23 and the end portions of the pixel electrodes 22, and a plurality of domains can be formed in one subpixel. Conventionally, the alignment of the liquid crystal molecules 23 is regulated by the protrusions 23 or slits formed in the pixels. However, since the end portions of the pixel electrodes 15 perform the same functions as the slits, the liquid crystal molecules are also formed at the end portions of the pixel electrodes 15. The inclination direction can be regulated.

  A polarizing plate and a λ / 4 phase difference plate are disposed outside the first substrate 11 and outside the second substrate 19, respectively. Each polarizing plate is set so that the transmission axes thereof are orthogonal to each other. 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. In addition, what is necessary is just to apply the structure described in the above-mentioned patent document 3 and Unexamined-Japanese-Patent No. 2000-29010 for the detail about the polarizing plate and phase difference plate in a transflective liquid crystal display panel.

  Note that a layer called a so-called top coat 37 is formed on the color filter 21 on the second substrate 19 at the reflection portion, and the distance of light passing through the liquid crystal layer 25 is approximately the same between the reflection portion and the light transmission portion. It is adjusted to.

  In the present invention, the problem that the conventional display hole 31 is deteriorated due to the presence of the contact hole 31 is prevented by arranging the protrusions 23 b so as to overlap the contact hole 31. FIG. 3 is a cross-sectional view taken along the line BB ′ of FIG. By forming the contact holes 31 and the protrusions 23b in such a manner that the contact holes 31 and the protrusions 23b overlap with each other, the inclination of the liquid crystal molecules due to the physical force of the contact holes 31 is suppressed by the restriction force of the protrusions 23b, and the contact holes 31 By concealing the influence on the display in the vicinity of 31, the deterioration of display quality is suppressed. Accordingly, the protrusion 23b is preferably sufficiently larger than the contact hole 31. In the embodiment, the size of the contact hole 31 is about 7 × 7 μm, whereas the shape of the protrusion 23b is first formed in an inverted Y shape, The width of the portion overlapping 31 is about 8 μm.

  In particular, in a reflective or transflective liquid crystal display panel having a reflective portion, a contact hole is formed in the reflective portion so that the TFT can be effectively used as a display. Therefore, since the drain electrode D is covered with the reflective electrode 15b ′ and has no influence on the display, the drain electrode D can be enlarged, and the position of the contact hole and the position of the protrusion can be easily overlapped.

  Next, the shape of the pixel electrode 15a and the like formed in the light transmission part will be described. Also in the present invention, the pixel electrode 15a in the light transmitting portion basically has an octagonal shape in which a corner portion is chamfered while being formed in substantially the entire rectangular light transmitting portion region. The alignment of the liquid crystal molecules in the light transmission part is regulated by the pixel electrode 15a and the protrusion 23 formed near the center of the pixel electrode 15a.

  In addition, the end portion of the pixel electrode 15 a overlaps the scanning line 12, and a protruding electrode 40 extending from the pixel electrode 15 a along the scanning line 12 direction is formed between the chamfered corner portion and the scanning line 12. Yes. Conventionally, at the position where the corner portion of the pixel electrode 15a is chamfered, the scanning line 12 is exposed, and the liquid crystal molecules are always inclined due to the potential difference generated between the scanning line 12 and the common electrode 22. Since the liquid crystal molecules are affected by the potential difference generated between the bump electrode 40 and the common electrode 22 by the bump electrode 40, the tilt of the liquid crystal molecules at the chamfered position can be prevented, and the reduction of contrast can be prevented.

  In particular, unlike the light transmission part through which light from the backlight always passes, the reflection part 15b ′ overlaps the scanning line 12 in order to secure the area as much as possible in the reflection part that reflects the unstable external light. Even if the liquid crystal molecules are tilted by the influence of the potential difference generated between the scanning line 12 and the common electrode 22 in the reflecting portion, the influence is small. However, in the light transmission portion, first, pixel electrodes 15a having chamfered corner portions are formed in order to uniformly regulate the alignment of liquid crystal molecules.

  Although the protruding electrode 40 is shown to overlap with the scanning line 12 in FIG. 1, it does not necessarily have to overlap. Since the liquid crystal molecules tilted by the potential difference generated between the scanning line 12 and the common electrode 22 do not affect the display, the scanning line 12 and the protruding electrode 40 may be in a surface position without overlapping. . However, the scanning lines 12 and the protruding electrodes 40 are formed so as to slightly overlap in consideration of mask displacement at the time of manufacture.

  In the embodiment, the protruding electrode 40 is about 4 μm and overlaps the scanning line 12 by about 2 μm. The size of the pixel electrode 15a in the light transmitting portion is about 60 × 40 μm, and the corner portion of the pixel electrode 15a having this size is chamfered. At the position where the distance between the end of the chamfered pixel electrode 15a and the protruding electrode 40 is maximum, the distance is about 9 μm.

  In the embodiment, the contact hole 31 is located in the drain electrode D constituting the TFT 16, but other switching elements such as so-called MIM may be used. The present invention can be applied as long as the electrode of the switching element and the pixel electrode are electrically connected through the contact hole.

  In addition, the basic shape of the pixel electrode 15a is an octagonal shape in the present embodiment, but a larger polygonal shape may be used, and the pixel electrode 15a may be an elliptical shape. In this way, any rectangular sub-pixel may be used as long as the corner portion of the pixel electrode is chamfered. In the present invention, the protruding electrode 40 is formed between the chamfering position of the corner portion generated by chamfering the corner portion of the pixel electrode and the scanning line, and the liquid crystal molecules are inclined between the corner portion and the scanning line. By controlling, the reduction in contrast is prevented.

FIG. 4 is a schematic plan view showing a pixel portion of a transflective liquid crystal display panel according to the present invention through a color filter. It is sectional drawing along the AA 'line of FIG. It is sectional drawing along the BB 'line of FIG. 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. FIG. 6 is a cross-sectional view taken along the line CC ′ of FIG. 5. It is a top view of the VA type transflective liquid crystal display panel which chamfered the corner of the conventional pixel electrode. Sectional drawing of the DD 'line of FIG. 7 is shown. FIG. 9 is a cross-sectional view taken along line EE ′ of FIG. 8.

Explanation of symbols

10: transflective liquid crystal display panel 13: scanning line 14: signal line 15: pixel electrode 15a: pixel electrode 15b in the light transmission part: pixel electrode 15b 'in the reflection part: reflection electrode
16: TFT
22: Common electrode 23b: Projection 31: Contact hole

Claims (7)

A first substrate on which switching elements and pixel electrodes are formed at respective positions partitioned by signal lines and scanning lines arranged in a matrix;
A second substrate on which a protrusion and a common electrode for regulating the inclination of liquid crystal molecules are formed;
An alignment film subjected to a vertical alignment treatment laminated on both the substrates;
In a liquid crystal display panel having a liquid crystal layer having a negative dielectric anisotropy disposed between the two substrates,
When viewed in plan, it is formed to overlap the previous SL protrusions contact hole for conduction between the pixel electrode and the electrode of the switching element,
The width of the protrusion is a liquid crystal display panel larger than the contact hole . The protrusion overlaps the contact hole at the approximate center of the pixel electrode,
The projection liquid crystal display panel according to 請 Motomeko 1 that not extend from substantially the center of the pixel electrode. It further includes a reflection part that reflects outside light ,
When viewed in plan, the liquid crystal display panel according to claim 1 or claim 2 wherein the Ru is formed to contact hole and said projection overlaps the reflecting portion. The respective position which is defined by the matrix on arranged signal lines and scanning lines, liquid crystal display panel according to 請 Motomeko 3 that also features a light transmissive portion. The protrusion overlaps the contact hole at the approximate center of the pixel electrode in the reflective portion,
The liquid crystal display panel according to claim 3, wherein the protrusion extends from substantially the center of the pixel electrode. The liquid crystal display panel according the shape of the protrusions of claims 1 an inverted Y-shape to claim 5. Wherein the lower portion of the drain electrode, the liquid crystal display panel according to claim 6 請 Motomeko 3 that has an auxiliary capacitance line so as to overlap with the drain electrode is formed.

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