Liquid crystal display device

A transflective liquid crystal display panel, in which at least one of a pixel electrode substrate and a counter electrode substrate is provided with a protruding portion so that the thickness of a liquid crystal layer in a reflective region is smaller than that in a transmissive region, wherein a light-blocking section for shading a defective orientation domain formed by an insufficiently-rubbed portion around the protruding portion is formed simultaneously with, and using the same material as, another element such as a storage capacitor electrode section, a signal line or a scanning line. Thus, the decrease in the display quality due to the defective orientation domain can be suppressed without adding to the production process.

This nonprovisional application calims priority under 35 U.S.C. §119(a) on Patent Application No. 2003-119370 filed in Japan on Apr. 24, 2003, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display panel used in a transflective (or transreflective) liquid crystal display device.

2. Description of the Background Art

For their advantageous features such as a small thickness and a small power consumption, liquid crystal display devices have recently been widely used in various applications, including OA apparatuses such as word processors and personal computers, PDAs (personal digital assistances) such as electronic organizers, and monitors of camera-incorporated VTRs.

These liquid crystal display devices are generally classified into those of transmissive type and those of reflective type. Unlike CRTs (cathode ray tubes) or EL (electroluminescence) devices, liquid crystal display devices are not self-luminous. In a transmissive liquid crystal display device, an image is displayed by using light from an illuminator (so-called “backlight”) provided on the back side of the liquid crystal display panel. In a reflective liquid crystal display device, an image is displayed by using ambient light.

Advantages and disadvantages of these types of liquid crystal display devices are as follows. A transmissive liquid crystal display device, which uses a backlight, is less influenced by the brightness of the environment, and is capable of displaying a bright image with a high contrast ratio. However, with the backlight, it consumes a large amount of power (the backlight accounts for about 50% or more of the total power consumption). Furthermore, the visibility lowers under a very bright environment (e.g., when used outdoors under a clear sky). Increasing the brightness of the backlight in order to maintain a sufficient visibility will further increase the power consumption. On the other hand, a reflective liquid crystal display device, which does not have a backlight, consumes little power, but the brightness and the contrast ratio thereof are substantially influenced by the conditions under which it is used, e.g., the brightness of the environment. Particularly, the visibility lowers significantly under dark environments.

In view of this, transflective liquid crystal display devices, which are capable of operating both in a transmissive mode and in a reflective mode, have been proposed in the art, in order to combine the advantages together while eliminating the disadvantages.

As schematically illustrated in the cross-sectional view ofFIG. 12, a transflective liquid crystal display device includes, for each pixel, a reflective pixel electrode section101for reflecting ambient light coming from the upper side of the figure, and a transmissive pixel electrode section102for transmitting light from the backlight coming from the lower side of the figure. The transflective liquid crystal display device is capable of displaying an image by using both display modes, or by selectively using a transmissive display mode or a reflective display mode according to the environment under which it is used (e.g., the brightness of the environment). Thus, the transflective liquid crystal display device provides both the advantage of a reflective liquid crystal display device (low power consumption) and that of a transmissive liquid crystal display device (being less influenced by the brightness of the environment and being capable of displaying a bright image with a high contrast ratio). Furthermore, the disadvantage of a transmissive liquid crystal display device (the lowering of the visibility under a very bright environment) is suppressed.

Moreover, in a transflective liquid crystal display device as described above, the thickness of a liquid crystal layer105between a counter electrode substrate103and a pixel electrode substrate104needs to be such that the thickness Rd in a reflective region R is smaller than the thickness Td in a transmissive region T (e.g., about ½ of Td (Rd≈Td×½)). Therefore, a protruding portion106is conventionally provided in the reflective region R of the pixel electrode substrate104, and the reflective pixel electrode section101on the protruding portion106, so that the thickness Rd of the liquid crystal layer105in the reflective region R is reduced by the thickness of the protruding portion106in the panel thickness direction, as described in U.S. Pat. No. 6,195,140 (Japanese Patent Application No. 11-101992), U.S. Pat. No. 6,295,109, United States Patent Application Publication No. 2003-0117551, U.S. patent application Ser. No. 10/260,248, U.S. patent application Ser. No. 10/689,086, etc.

SUMMARY OF THE INVENTION

In a liquid crystal display panel used in a transflective liquid crystal display device as described above, when the pixel electrode substrate104is subjected to a rubbing treatment, an insufficiently-rubbed portion S occurs around the protruding portion106(particularly, in a portion of the transmissive region T downstream (on the right hand side inFIG. 12) of the protruding portion106with respect to the rubbing direction). The term “upstream/downstream” will be used with respect to the rubbing direction throughout this specification unless otherwise specified. The insufficiently-rubbed portion S is shaded by the protruding portion106from the rubbing, and is not sufficiently rubbed, thereby providing a weak orientation-regulating force on liquid crystal molecules105a.

Then, a region of the liquid crystal layer105corresponding to the insufficiently-rubbed portion S becomes a defective orientation domain that is visually perceived as a domain. Thus, the conventional arrangement has a problem that the display quality lowers especially in the transmissive display mode. Note that this problem occurs also when the protruding portion106is provided on the counter electrode substrate103, instead of on the pixel electrode substrate104.

This problem may be solved by providing a light-blocking portion for shading the defective orientation domain.

However, the provision of such a light-blocking portion adds to the production process and may increase the production cost.

Therefore, it is an object of the present invention to provide a transflective liquid crystal display device, in which each pixel has a reflective region and a transmissive region, and at least one of the pixel electrode substrate and the counter electrode substrate is provided with a protruding portion so that the thickness of the liquid crystal layer in the reflective region is smaller than that in the transmissive region, wherein the decrease in the display quality due to a defective orientation domain formed by an insufficiently-rubbed portion around the protruding portion can be suppressed without adding to the production process.

In order to achieve this object, according to the present invention, when an element or elements of the transflective liquid crystal display device (such as a storage capacitor electrode section for storing a signal, which is formed so as to correspond to a pixel electrode section, or a signal line and a scanning line for applying a signal to the pixel electrode section) is or are formed, a light-blocking section is formed simultaneously with, and using the same material as, the element or elements, whereby it is possible to block a defective orientation domain formed by an insufficiently-rubbed portion around a protruding portion without adding to the production process.

Note that the light-blocking section may be formed through a step of forming another element using the same material as that of the other element, or may be formed through steps of forming different other elements using the same materials as those of the other elements.

Moreover, the light-blocking section may be an extension of, and integral with, the other element or elements, separate from the other element or elements, or a mix thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1andFIG. 2schematically illustrate an important part of a liquid crystal display panel of a transflective liquid crystal display device according to Embodiment 1 of the present invention. The liquid crystal display device displays an image using both the transmissive display mode and the reflective display mode. Note thatFIG. 1is a cross-sectional view taken along line I—I ofFIG. 2, andFIG. 2is a schematic plan view of a pixel electrode substrate as seen from the counter electrode substrate side.

The liquid crystal display panel of the liquid crystal display device includes a TFT substrate20as the pixel electrode substrate, and a color filter substrate10(hereinafter referred to as a “CF substrate”) as the counter electrode substrate. The TFT substrate20includes a reflective pixel electrode section21(not shown inFIG. 2) and a transmissive pixel electrode section22(not shown inFIG. 2) for each pixel. The CF substrate10includes a counter electrode section11, which is arranged so as to oppose the reflective pixel electrode section21and the transmissive pixel electrode section22for each pixel in the TFT substrate20. In the TFT substrate20, the reflective pixel electrode section21is arranged in a central portion of the pixel, and the transmissive pixel electrode section22is arranged in a peripheral portion of the pixel so as to surround the reflective pixel electrode section21. In the CF substrate10, the counter electrode section11extends over a plurality of pixels. A liquid crystal layer40is provided between the substrates20and10. The liquid crystal display panel operates in an ECB (Electrically Controlled Birefringence) mode, wherein incident light is selectively transmitted or blocked by utilizing the birefringence of liquid crystal molecules40aof the liquid crystal layer40while changing the orientation of the liquid crystal molecules40aby the application of an electric field. The liquid crystal display panel includes a backlight (not shown) on the TFT substrate20side (the lower side inFIG. 1).

The TFT substrate20includes a transparent substrate23made of an electrically insulative, transparent material such as a glass. A plurality of signal lines24and a plurality of scanning lines25are arranged on the transparent substrate23so as to cross each other in a lattice pattern defining a matrix of pixels therein for applying a signal to the reflective pixel electrode section21and the transmissive pixel electrode section22of each pixel. A TFT26(Thin Film Transistor) is provided in the vicinity of the intersection between each signal line24and each scanning line25. Each TFT26includes a source electrode26a, a drain electrode26band a gate electrode26c, and a gate insulating film26dis provided between the source and drain electrodes26aand26band the gate electrode26c. The signal line24and the scanning line25are electrically connected to the source electrode26aand the gate electrode26c, respectively. Moreover, the drain electrode26bextends to a central portion of the pixel, and the drain electrode26band the source electrode26aare covered by a protection layer27.

An insulating layer28is provided over the signal line24, the scanning line25and the TFT26, and the reflective pixel electrode section21and the transmissive pixel electrode section22are provided on the insulating layer28. A contact hole28ais running in the thickness direction through the insulating layer28in a portion of the insulating layer28that opposes a central portion of the reflective pixel electrode section21in the panel thickness direction. The reflective pixel electrode section21is electrically connected to the drain electrode26bof the TFT26via the contact hole28a. On the transparent substrate23side of the insulating layer28, a capacitor electrode line29extends parallel to the scanning line25. A storage capacitor electrode section29a(hereinafter referred to as a “Cs electrode section”) for storing a signal is formed along the capacitor electrode line29so as to oppose the reflective pixel electrode section21in the panel thickness direction. Note that the gate insulating film26dof the TFT26extends over the storage capacitor electrode line29and the Cs electrode section29a.

The reflective pixel electrode section21is made of a light-reflecting metal film such as an aluminum (Al) film. On the other hand, the transmissive pixel electrode section22is made of a light-transmitting transparent conductive film such as an ITO (Indium Tin Oxide) film. A side surface of the transmissive pixel electrode section22is electrically connected to a side surface of the reflective pixel electrode section21. An alignment film30, which has been rubbed in a predetermined direction, is provided over the reflective pixel electrode section21and the transmissive pixel electrode section22, whereby the liquid crystal molecules40ain the vicinity of the interface between the TFT substrate20and the liquid crystal layer40are aligned in the predetermined direction and parallel to the TFT substrate20. Note that while the reflective metal film of the reflective pixel electrode section21and the transparent conductive film of the transmissive pixel electrode section22are connected to each other with the side surfaces thereof abutting each other in the present embodiment, they may alternatively be connected to each other with an end portion of the reflective metal film and an end portion of the transparent conductive film overlap each other. Alternatively, the transparent conductive film of the transmissive pixel electrode section22may be extended to the reflective pixel electrode section21, while arranging a reflective metal film over the extended portion of the transparent conductive film, thereby providing the reflective pixel electrode section21.

The CF substrate10also includes a transparent substrate12made of an electrically insulative, transparent material such as a glass. On the liquid crystal layer40side of the transparent substrate12, a color filter layer13is provided for each pixel. An opening13ais running in the thickness direction through the color filter layer13in a portion of the color filter layer13that opposes a central portion of the reflective pixel electrode section21in the panel thickness direction, and the counter electrode section11is provided on the color filter layer13. The counter electrode section11is also made of a transparent conductive film such as an ITO film, as is the transmissive pixel electrode section22. Moreover, an alignment film14, which has been rubbed in a predetermined direction indicated by an arrow inFIG. 1andFIG. 2(the rightward direction inFIG. 1and the upward direction inFIG. 2), is provided on the counter electrode section11, whereby the liquid crystal molecules40ain the vicinity of the interface between the CF substrate10and the liquid crystal layer40are aligned in the predetermined direction (the rubbing direction) and parallel to the CF substrate10.

In each pixel, a region corresponding to the reflective pixel electrode section21is the reflective region R, where light entering the liquid crystal display panel from the CF substrate10side (the upper side inFIG. 1) is reflected by the reflective pixel electrode section21out of the liquid crystal display panel through the CF substrate10in the reflective display mode. On the other hand, a region corresponding to the transmissive pixel electrode section22is the transmissive region T, where light from the backlight entering the liquid crystal display panel from the TFT substrate20side (the lower side inFIG. 1) is transmitted out of the liquid crystal display panel through the CF substrate10in the transmissive display mode.

In the present embodiment, the CF substrate10is provided with a protruding portion15for each pixel so that the thickness Rd of the liquid crystal layer40in the reflective region R is smaller than the thickness Td of the liquid crystal layer40in the transmissive region T (Rd<Td). With the protruding portions15, the CF substrate10has a so-called “multigap structure”. Note that the phantom line inFIG. 2schematically shows the contour of the top surface of the protruding portion15.

Specifically, the protruding portion15is formed by a transparent layer16. The transparent layer16is provided between the color filter layer13and the counter electrode section11in the reflective region R so as to raise a portion of the counter electrode section11in the reflective region R in the panel thickness direction toward the reflective pixel electrode section21(in the downward direction inFIG. 1). The shape and size of the top surface of the protruding portion15are generally the same as those of the reflective pixel electrode section21.

The protruding portion15is formed by the transparent layer16, as described above, thereby avoiding a decrease in the optical transmittance in the reflective region R, which occurs when a protruding portion is formed by increasing the thickness of the color filter layer13. Furthermore, the opening13aof the color filter layer13is filled with a portion of the transparent layer16, whereby it is possible to increase the optical transmittance in the reflective region R without substantially detracting from the function of the color filter layer13by the provision of the opening13a, as compared with a case where the color filter layer13has no opening13a. Note that the method of forming the transparent layer16as described above may include, for example, forming a film of a negative-type transparent acrylic-resin photosensitive material on the transparent substrate12, exposing the film to activation light in a predetermined pattern, developing the film with an alkaline developing solution and washing the film with water to remove the unexposed portions, and then subjecting the film to a heat treatment. Alternatively, it may be provided by patterning by etching, printing, transferring, etc.

In the present embodiment, the Cs electrode section29ais extended downstream of the protruding portion15, as illustrated inFIG. 1andFIG. 2, so as to shade a defective orientation domain D formed by the insufficiently-rubbed portion S downstream (on the right hand side inFIG. 1and on the upper side inFIG. 2) of the protruding portion15on the CF substrate10. The extended portion forms a light-blocking section50of the present invention. Note that a portion upstream (on the left hand side inFIG. 1and on the lower side inFIG. 2) of the protruding portion15is less likely to be an insufficiently-rubbed portion. Therefore, the upstream end of the Cs electrode section29ais generally aligned with the upstream end of the protruding portion15with respect to the rubbing direction.

The process of producing the liquid crystal display panel having such a structure, up to the step of forming the protection layer27on the TFT substrate20, will now be described with reference toFIG. 3AtoFIG. 3N.

A TaN/Ta/TaN film is deposited by sputtering on the transparent substrate23, as illustrated inFIG. 3B, in order to form the scanning line25, the gate electrode26c, the capacitor electrode line29, and the Cs electrode section29aincluding the light-blocking section50, which is formed as an extended portion of the Cs electrode section29a.

A photoresist film is deposited on the TaN/Ta/TaN film, as illustrated inFIG. 3C.

The photoresist film is irradiated with UV light via a photomask (seeFIG. 3D). The photomask used in this step is patterned so that the light-blocking portions thereof correspond to the shapes of the scanning line25, the gate electrode26c, the capacitor electrode line29and the Cs electrode section29a. The light-blocking portion corresponding to each Cs electrode section29ais extended by a predetermined amount in the downstream direction so as to form two light-blocking sections50and50.

Unnecessary portions of the TaN/Ta/TaN film are removed by dry etching using a mixed gas of CF4and O2, as illustrated inFIG. 3E. Thus, the scanning line25, the gate electrode26c, the capacitor electrode line29, the Cs electrode section29aand the light-blocking section50are formed. Therefore, the light-blocking section50is formed during the step of forming the scanning line25and the Cs electrode section29aby using the same material as that of the scanning line25and the Cs electrode section29a.

The remaining resist film is stripped, as illustrated inFIG. 3F.

The surface of the gate electrode26cis oxidized by an anodic oxidation method to produce Ta2O5(seeFIG. 3G).

The gate insulating film26d(e.g., an SiNx film) is deposited substantially across the entire surface by a plasma CVD method (seeFIG. 3H).

An amorphous silicon−i layer is formed by a plasma CVD method on a portion of the gate insulating film26dcorresponding to the gate electrode26c(seeFIG. 3I).

An amorphous silicon n+layer is formed by a plasma CVD method on the amorphous silicon−i layer.

The n+layer and the−i layer are simultaneously patterned by dry etching.

An ITO film is deposited by sputtering on the amorphous silicon n+layer, and a Ta/TaN film is deposited by sputtering on the ITO film, as illustrated inFIG. 3J.

The Ta/TaN film is patterned by dry etching to form the signal line24, as illustrated inFIG. 3K.

The ITO film formed in Step 12 is patterned by wet etching, as illustrated inFIG. 3L.

The n+layer is divided by dry etching into two pieces, one on the source electrode26aside and another on the drain electrode26bside. In this step, a portion of the−i layer is also etched away. After this step, the source electrode26aand the drain electrode26bof the TFT26are completed, as illustrated inFIG. 3M.

An SiNx film for forming the protection layer27is formed by a plasma CVD method, as illustrated inFIG. 3N.

The SiNx film is patterned by wet etching to form the protection layer27.

Through Steps 1 to 17 above, the TFT26, the signal line24, the scanning line25, the capacitor electrode line29, the Cs electrode section29aand the light-blocking section50are formed on the transparent substrate23. Thus, in the present embodiment, the light-blocking section50can be formed only by changing the photomask in Step 4. Then, the insulating layer28, the reflective and transmissive pixel electrode sections21and22and the alignment film30are formed sequentially, thereby obtaining the TFT substrate20.

The following experiments were conducted for examining the relationship between the thickness Wd of the transparent layer16(the height of the protruding portion15) and the size in the rubbing direction of the defective orientation domain D formed by the insufficiently-rubbed portion S in the downstream vicinity of the protruding portion15in the liquid crystal display panel of the liquid crystal display device having such a structure.

In Experiments 1 to 3, three liquid crystal display panels were produced, each having a different thickness Wd of the transparent layer16according to the thicknesses Rd and Td of the liquid crystal layer40in the reflective region R and the transmissive region T. For each liquid crystal display panel produced, the size in the rubbing direction of the defective orientation domain D was measured.

In Experiment 1, the thicknesses Rd and Td of the liquid crystal layer40in the reflective region R and the transmissive region T were set to Rd=2.5 μm and Td=5.0 μm, respectively. Thus, the thickness Wd of the transparent layer16was Wd=2.5 μm (=5.0−2.5).

In Experiment 2, the thicknesses Rd and Td of the liquid crystal layer40in the reflective region R and the transmissive region T were set to Rd=3.0 μm and Td=4.0 μm, respectively. Thus, the thickness Wd of the transparent layer16was Wd=1.0 μm (=4.0−3.0).

In Experiment 3, the thicknesses Rd and Td of the liquid crystal layer40in the reflective region R and the transmissive region T were set to Rd=2.0 μm and Td=5.5 μm, respectively. Thus, the thickness Wd of the transparent layer16was Wd=3.5 μm (=5.5−2.0).

The results are shown in Table 1 below (unit: μm).

As shown in Table 1 above, the size M in the rubbing direction of the defective orientation domain D was 2.0 μm, 1.0 μm and 3.0 μm in Experiments 1, 2 and 3, respectively. Therefore, it can be seen that the amount of extension of the Cs electrode section29ain the downstream direction, i.e., the size M in the rubbing direction of the light-blocking section50, needs to be 1 μm or more (M≧1 μm).

Thus, the present embodiment provides a transflective liquid crystal display device, in which each pixel has the reflective region R and the transmissive region T, and a plurality of protruding portions15are provided on the CF substrate10so that each protruding portion15corresponds to the reflective region R, whereby the thickness Rd of the liquid crystal layer40in the reflective region R is smaller than the thickness Td of the liquid crystal layer40in the transmissive region T. When forming the Cs electrode section29aon the TFT substrate20, the Cs electrode section29ais extended in the downstream direction. In this way, the light-blocking section50for shading the defective orientation domain D formed by the insufficiently-rubbed portion S in the downstream vicinity of each protruding portion15on the CF substrate10can be formed simultaneously with, and using the same material as, the Cs electrode section29a. Thus, the decrease in the display quality in the transmissive display mode due to the defective orientation domain D can be suppressed without adding to the process of producing a liquid crystal display panel.

Note that in the present embodiment, the reflective pixel electrode section21and the transmissive pixel electrode section22are electrically connected to each other, so that an image can be displayed by using both the transmissive display mode and the reflective display mode. Alternatively, the reflective pixel electrode section21and the transmissive pixel electrode section22may not be connected to each other, and a signal from the signal line24may be supplied selectively to the reflective pixel electrode section21or the transmissive pixel electrode section22, so that an image can be displayed by selectively using the transmissive display mode or the reflective display mode.

Moreover, while the present embodiment is directed to a color liquid crystal display device, the present invention may alternatively be applied to a black-and-white liquid crystal display device.

FIG. 4is a plan view illustrating an important part of a liquid crystal display panel of a liquid crystal display device according to Embodiment 2 of the present invention. Note that those elements already described in Embodiment 1 are denoted by the same reference numerals.

In the present embodiment, the Cs electrode section29ais extended in the upstream direction (the downward direction inFIG. 4), in addition to being extended in the downstream direction (the upward direction inFIG. 4) as in Embodiment 1. The extended portion in the upstream direction forms the light-blocking section50for shading the defective orientation domain D formed by the insufficiently-rubbed portion S in the upstream vicinity of each protruding portion15on the CF substrate10. Other than this, the present embodiment has the same structure as that of Embodiment 1, which will not be further described below.

The structure of the present embodiment is based on the fact that when rubbing the substrate having the protruding portions15(the CF substrate10in the present embodiment), although the insufficiently-rubbed portion S typically occurs downstream of the protruding portion15, it may also occur upstream of the protruding portion15. The structure of the present embodiment allows for designs with greater margins with respect to the defective orientation domain D formed by the insufficiently-rubbed portion S around the protruding portion15.

Thus, according to the present embodiment, although the size of the transmissive region T is reduced as compared with Embodiment 1, it is possible to further suppress the decrease in the display quality in the transmissive display mode due to the defective orientation domain D formed by the insufficiently-rubbed portion S around the protruding portion15.

Note that in the present embodiment, the Cs electrode section29ais extended downstream and upstream of the protruding portion15. However, an insufficiently-rubbed portion may also occur beside the protruding portion15, i.e., in locations neighboring the protruding portion15in a direction perpendicular to the rubbing direction and parallel to the substrate plane, although not as often as those occurring in the downstream vicinity and the upstream vicinity of the protruding portion15. Thus, the Cs electrode section29amay be extended not only in the upstream/downstream directions, but also in the lateral directions as described above. In this way, it is possible to substantially completely shade defective orientation domains formed by insufficiently-rubbed portions around the protruding portion15.

FIG. 5is a cross-sectional view schematically illustrating a liquid crystal display panel of a liquid crystal display device according to Embodiment 3 of the present invention. Note that those elements already described in Embodiment 1 are denoted by the same reference numerals.

As in Embodiments 1 and 2, the liquid crystal display panel of this liquid crystal display device includes the TFT substrate20and the CF substrate10, wherein the TFT substrate20includes the reflective pixel electrode section21and the transmissive pixel electrode section22for each pixel, and the CF substrate10includes the counter electrode section11, which is arranged so as to oppose the reflective pixel electrode section21and the transmissive pixel electrode section22of the TFT substrate20.

The present embodiment differs from Embodiments 1 and 2 in that the protruding portions15are formed on the TFT substrate20, instead of on the CF substrate10. Therefore, the surface of the CF substrate10closer to the liquid crystal layer40is flat.

The liquid crystal layer40has the same thickness as that of the embodiments above. Specifically, the height of the protruding portion15is determined so that the thickness Rd in the reflective region R corresponding to the reflective pixel electrode section21is about one half of the thickness Td in the transmissive region T corresponding to the transmissive pixel electrode section22(Rd≈Td/2) in each pixel.

Moreover, the Cs electrode section29ais extended in the downstream direction (the rightward direction inFIG. 5) and in the upstream direction (the leftward direction inFIG. 5), as in Embodiment 2. These two extended portions form two light-blocking sections50, one for shading the defective orientation domain D formed by the insufficiently-rubbed portion S in the downstream vicinity of the protruding portion15and another for shading the defective orientation domain D formed by the insufficiently-rubbed portion S upstream of the protruding portion15. Other than this, the present embodiment has the same structure as those of Embodiments 1 and 2, which will not be further described below.

Thus, according to the present embodiment, similar effects to those of Embodiment 2 can be provided also when the protruding portions15forming a multigap structure are provided on the TFT substrate20.

Note that in the present embodiment, the Cs electrode section29ais extended downstream and upstream of the protruding portion15. Alternatively, the Cs electrode section29amay be extended only in the downstream direction as in Embodiment 1, or may be extended in the lateral directions beside the protruding portion15in addition to the downstream/upstream directions as described above as a variation of Embodiment 2.

FIG. 6is a plan view schematically illustrating an important part of a liquid crystal display panel of a liquid crystal display device according to Embodiment 4 of the present invention. Note that those elements already described in Embodiments 1 to 3 are denoted by the same reference numerals.

In the present embodiment, the protruding portions15are provided on the TFT substrate20so as to run across a plurality of pixels in the scanning line direction (in the horizontal direction inFIG. 6). Each reflective pixel electrode section21is also running across a plurality of pixels in the scanning line direction on the top surface of the corresponding protruding portion15.

Thus, while the protruding portions15are arranged in an island-like pattern so that each separate protruding portion15corresponds to one pixel in Embodiments 1 to 3, the protruding portions15are arranged in stripes so that each separate protruding portion15continuously extends across a plurality of pixels in the present embodiment. Accordingly, the entire portion of the capacitor electrode line29located within a pixel is widened in the signal line direction (in the vertical direction inFIG. 6) to form the Cs electrode section29a.

In the present embodiment, the Cs electrode section29ais extended downstream of the protruding portion15(in the upward direction inFIG. 6), as in Embodiment 1. The extended portion forms the light-blocking section50for shading the defective orientation domain D formed by the insufficiently-rubbed portion S in the downstream vicinity of the protruding portion15. Other than this, the present embodiment has the same structure as that of Embodiment 1, which will not be further described below.

Thus, similar effects to those of Embodiment 1 can also be provided by the present embodiment.

Note that in the present embodiment, the Cs electrode section29ais only extended downstream of the protruding portion15. Alternatively, as shown in the variation ofFIG. 7, the Cs electrode section29amay be extended upstream of the protruding portion15(in the downward direction inFIG. 7), in addition to being extended downstream of the protruding portion15(in the upward direction inFIG. 7) to form the light-blocking sections50upstream and downstream of the protruding portion15, as in Embodiment 2.

FIG. 8is a plan view schematically illustrating an important part of a liquid crystal display panel of a liquid crystal display device according to Embodiment 5 of the present invention. Note that those elements already described in Embodiment 1 are denoted by the same reference numerals.

In the present embodiment, the reflective pixel electrode section21has an open rectangular shape, and is arranged on the TFT substrate20along the periphery of each pixel, whereas the transmissive pixel electrode section22has a solid rectangular shape and is arranged in a central portion of each pixel so as to be surrounded by the reflective pixel electrode section21.

Accordingly, the protruding portion15as viewed in a plan view has an open rectangular shape, conforming to the planar shape of the reflective pixel electrode section21, and is arranged in a peripheral portion of each pixel. Thus, the protruding portions15,15, . . . , are arranged in a lattice pattern defining a matrix of pixels therein, as are the signal line24and the scanning line25, and as opposed to the island-like pattern of Embodiments 1 to 3 or the stripe pattern of Embodiment 4.

In the present embodiment, one of two adjacent scanning lines25and25that is located on the upstream side (the lower side inFIG. 8) is extended in the downstream direction (the upward direction inFIG. 8), and the extended portion forms the light-blocking section50for shading the defective orientation domain D formed by the insufficiently-rubbed portion S in the downstream vicinity of one of the four sides of the protruding portion15that extends in a direction perpendicular to the rubbing direction on the upstream side of the pixel. Other than this, the present embodiment has the same structure as that of Embodiment 1, which will not be further described below.

In this arrangement, the protruding portion15is relatively shifted from the scanning line25in the direction (the downward direction inFIG. 8) opposite to the rubbing direction, so that the light-blocking section50, which is an extended portion of the scanning line25, is located in the downstream vicinity of the upstream side of the protruding portion15.

Thus, the same effects as those of Embodiment 1 can also be provided by the present embodiment.

Note that in the present embodiment, one of the four lines (two signal lines24and two scanning lines25) surrounding each pixel, i.e., the upstream-side scanning line25, is extended in the downstream direction. Alternatively, in order to shade a defective orientation domain formed by an insufficiently-rubbed portion in the upstream vicinity of the downstream side of the protruding portion15, the downstream-side scanning line25may be extended in the upstream direction. Alternatively, in order to additionally shade defective orientation domains formed by insufficiently-rubbed portions beside the protruding portion15, i.e., those neighboring the protruding portion15in a direction perpendicular to the rubbing direction and parallel to the substrate plane, the remaining two of the four lines surrounding each pixel, i.e., two signal lines24, may be extended in the respective lateral directions.

Moreover, while the present embodiment is directed to an arrangement where the reflective pixel electrode section21and the protruding portion15are provided only in a peripheral portion of each pixel, the present invention may alternatively be applied to an arrangement where they are provided not only in a peripheral portion but also in a central portion of each pixel, as shown in the variation ofFIG. 9. Such an arrangement can be accommodated by using the light-blocking sections of the previous embodiments (i.e., by extending the Cs electrode section29ato form the light-blocking section50). Thus, where the light-blocking section50is formed to be integral with another element, the light-blocking section50may be formed simultaneously with, and using the same material as, a selected one of a plurality of elements including the signal line24, the scanning line25and the Cs electrode section29a, and the selection can appropriately be made in view of the location where the defective orientation domain is formed.

FIG. 10is a plan view schematically illustrating an important part of a liquid crystal display panel of a liquid crystal display device according to Embodiment 6 of the present invention. Note that those elements already described in Embodiments 1 to 5 are denoted by the same reference numerals.

In the present embodiment, the protruding portions15each have a generally rectangular shape, and are arranged in an island-like pattern on the TFT substrate20so that each protruding portion15is located in a central portion of a pixel. The present embodiment differs from Embodiments 1 to 5 in that the rubbing direction for the TFT substrate20is not parallel to the signal line24, but is at a predetermined angle θ (0°<θ<90°) with respect to the signal line24. Thus, where the Cs electrode section29ahas a generally rectangular shape, two of the four sides of the Cs electrode section29aare present on the downstream side.

In the present embodiment, the two sides of the Cs electrode section29aare extended in the downstream direction respectively along the signal line24and along the scanning line25. The extended portion having a planar L-letter shape forms the light-blocking section50for shading the defective orientation domain D formed by the insufficiently-rubbed portion S occurring in the downstream vicinity of the protruding portion15.

Now, the area P of the Cs electrode section29aincluding the extended portion thereof (the light-blocking section50) will be discussed with reference toFIG. 11. Where “j” and “k” denote the length (unit: μm) of the Cs electrode section29ain the scanning line direction (in the horizontal direction inFIG. 10) and that in the signal line direction (in the vertical direction inFIG. 10), respectively, the area P′ of the Cs electrode section29aitself is:
P′=j×k.

The amount of extension (unit: μm) of the Cs electrode section29ain the scanning line direction and that in the signal line direction can be obtained as follows. As can be seen from the results shown in Table 1 above, the size in the rubbing direction of the defective orientation domain D is at least 1 μm. Therefore, the amount of extension in the scanning line direction is at least:
1×sin θ=sin θ, and
the amount of extension in the signal line direction is at least:
1×cos θ=cos θ.

Note that in a case where the reflective pixel electrode section21and the protruding portion15are arranged in a stripe pattern, running across a plurality of pixels, with the capacitor electrode line29being widened across its entire length to form the Cs electrode section29a, as in Embodiment 4, the Cs electrode section29acan be extended by cos θ in the downstream direction along the signal line.

Thus, according to the present embodiment, similar effects to those of Embodiments 1 to 5 can also be provided when the rubbing direction is not parallel to the signal line direction.

Note that in the present embodiment, the amount of extension of the Cs electrode section29ais calculated based on the relationship between the rubbing direction and the signal line direction. Alternatively, the amount of extension may be calculated based on the relationship between the rubbing direction and the scanning line direction.

Moreover, while Embodiments 1 to 6 above are directed to arrangements where the Cs electrode section29a, the scanning line25and/or the signal line24is extended to form the light-blocking section50, the protruding portion15may be shrunk so that a portion of the Cs electrode section29a, the scanning line25or the signal line24that is no longer covered by the shrunk protruding portion15functions as the light-blocking section50.

Moreover, while the light-blocking section50is formed to be integral with another element such as the Cs electrode section29a, the scanning line25or the signal line24in Embodiments 1 to 6 above, the light-blocking section50may alternatively be separate from the other element as long as it is formed simultaneously with, and using the same material as, the other element.

Furthermore, while the embodiments above are directed to suppressing the decrease in the display quality in the transmissive display mode due to the defective orientation domain D formed in the transmissive region T, the present invention is not limited to this. In a case where a defective orientation domain is formed in the reflective region R, the light-blocking section50can be formed from a material with a low optical reflectivity, e.g., a black conductive material, whereby it is possible to suppress the reflection of incident light in the defective orientation domain D, and thus it is possible to suppress the decrease in the display quality in the reflective display mode due to the defective orientation domain D formed in the reflective region R.