JP2006039125A - Liquid crystal display, and its manufacturing method and manufacturing equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method that does not generate stripe uneveness on an alignment film face, and provide manufacturing equipment and a liquid crystal display. <P>SOLUTION: The manufacturing method of the liquid crystal display for providing the alignment film on a pair of opposite substrates in feature as the manufacturing method of the liquid crystal display comprises mounting a mask providing an opening part on the surface of the substrate by possessing conductivity and having rubbing processing, in a state in which it is electrically connected to the outside so as to make prescribed potential of the mask. In the manufacturing method comprising this constitution, since the mask in which rubbing cloth is contacted has conductivity and is electrically connected to the outside in the rubbing processing, charging of the rubbing cloth can be suppressed. Thereby since the rubbing processing can be applied uniformly on the alignment film face, stripe uneveness can be prevented from occurring due to static electricity. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a liquid crystal display device and a liquid crystal display device obtained thereby.

  The liquid crystal display device is applied to various products such as a liquid crystal television, a notebook PC, a PDA, and a mobile phone in order to enable low power consumption, thinness, and space saving. The liquid crystal display device includes a liquid crystal panel in which a liquid crystal is sandwiched between two substrates on which a transparent electrode is deposited and an alignment film is applied, and a driving driver. The liquid crystal is aligned in the direction in which the alignment film applied to the glass substrate is rubbed with a rubbing cloth. By applying an electric field to the liquid crystal in the liquid crystal panel with a driver for driving, the alignment direction of the liquid crystal is changed, and the amount of transmitted light is controlled for display. The rubbing direction determines the visual characteristics of the liquid crystal display device. As a result, the liquid crystal display device has a visual characteristic that looks different depending on the viewing direction, and has a problem that visibility is deteriorated depending on the viewing direction.

  In order to solve this problem, it is proposed that the rubbing process is performed using a mask having a plurality of minute openings in the one described in Patent Document 1. In this method, first, a first rubbing process is performed on the entire surface while rotating a rubbing roller around which a rubbing cloth is wound around a substrate coated with an alignment film. Next, the mask having a plurality of minute openings is placed on the surface of the substrate, and the alignment film exposed from the openings is rubbed in a direction different from the first time, for example, 180 degrees. By the above operation, a plurality of alignment treatment regions having different rubbing directions are provided on one substrate. The other substrate is also subjected to the same rubbing treatment, and the two substrates are combined so that the rubbing directions are different by 90 degrees. Accordingly, it is an object to obtain a liquid crystal display device having excellent viewing angle characteristics.

In Patent Document 2, the first rubbing process is performed in a certain direction on the entire surface, and a photosensitive resist is formed on the alignment film before the second rubbing process, and this is subjected to pattern exposure and development. In addition, a method is disclosed in which a part of the alignment film surface that is partially exposed is subjected to a second rubbing treatment and then the resist is completely removed. The other substrate is also subjected to the same rubbing process, and the two substrates in which the regions in the rubbing direction that differ by 180 degrees on each substrate are formed in predetermined portions are combined so that the rubbing direction differs by 90 degrees. Accordingly, it is an object to obtain a liquid crystal display device having excellent viewing angle characteristics.
JP-A-7-239474 JP-A-11-352486

  However, the alignment processing method by rubbing has a problem that streaky irregularities (straight irregularities) that drastically reduce the display quality are likely to occur when the liquid crystal display device is completed. Focusing on this problem, the inventors of the present application diligently studied and found that there are two types of the streaks, thick stripes and fine stripes. The cause of the thick streaks is that the rubbing cloth is charged during rubbing, the hair of the cloth is twisted, the way the hair hits the alignment film surface varies depending on the location, and the rubbing density is uneven. It is considered a thing. Another possible cause is that the pattern of the panel terminal portion is electrostatically transferred. On the other hand, the cause of the fine stripes is considered to be that fine alignment marks are formed on the alignment film surface by performing rubbing treatment while dragging minute dust generated during rubbing.

  This invention is made | formed in view of the said problem, and it aims at providing the manufacturing method, manufacturing apparatus, and liquid crystal display device which do not generate | occur | produce the said uneven stripe on the said alignment film surface.

  In order to achieve the above object, the present invention has been made, and a feature as a method of manufacturing a liquid crystal display device according to the present invention is a method of manufacturing a liquid crystal display device in which an alignment film is provided on a pair of opposing substrates. A rubbing treatment is performed in a state where a mask having conductivity and an opening is placed on the surface of the substrate and electrically connected to the outside so that the mask has a predetermined potential. There is in point to do. In the manufacturing method having this configuration, since the mask with which the rubbing cloth comes into contact during the rubbing process has conductivity and is electrically connected to the outside, charging of the rubbing cloth can be suppressed, Thereby, since the rubbing process can be uniformly performed on the alignment film surface, it is possible to prevent the occurrence of stripe unevenness due to static electricity.

  In addition, the method for manufacturing a liquid crystal display device according to the present invention can be used for forming a horizontal alignment film, but is preferably used for manufacturing a liquid crystal display device having a vertical alignment film. That is, in the case of a liquid crystal panel obtained by enclosing a liquid crystal having negative dielectric anisotropy with a substrate on which the vertical alignment film is formed, the liquid crystal panel is slightly inclined from 90 degrees (typically 0.1 to several degrees). Degree) pretilt angle appears, and this minute tilt unevenness tends to lead to a decrease in display quality. For this reason, it is necessary to control the pretilt angle when the vertical alignment film is employed, and the deterioration of display quality can be prevented by forming the vertical alignment film using the method for manufacturing a liquid crystal display device according to the present invention. Can do.

  Further, in the method for manufacturing a liquid crystal display device according to the present invention, it is preferable to form at least two different alignment regions in one pixel when the alignment treatment is performed on the alignment film. Visibility can be improved.

  In the method of manufacturing a liquid crystal display device according to the present invention, a configuration in which a ground potential (GND) is used as the “predetermined potential” for electrically connecting the mask to the outside so as to have a predetermined potential is adopted. Preferably, this can suppress charging of the rubbing cloth.

  Further, the liquid crystal display device manufacturing method according to the present invention preferably employs a configuration in which electrodes formed on a substrate to be rubbed are electrically connected so as to have the same potential as the mask. Thus, charging of the rubbing cloth can be further suppressed.

  Moreover, it is preferable that the manufacturing method of the liquid crystal display device according to the present invention adopts a configuration in which a rubbing roller that performs the alignment treatment on the alignment film is electrically connected so as to have the same potential as the mask. Thus, charging of the rubbing cloth can be suppressed.

  Further, in the method for manufacturing a liquid crystal display device according to the present invention, it is preferable that the difference in the frictional voltage between the rubbing cloth of the rubbing roller and the alignment film that is in direct contact is small, thereby suppressing the occurrence of uneven stripes. can do. Whether a substance is positively charged or negatively charged depends on whether it is in contact with the substance (referred to as “substance A” for convenience in this description) or another substance (referred to as “substance B” for convenience in this description). It depends on. That is, the frictional voltage of the substance A is positive when the frictional voltage of the substance B is on the negative side of that of the substance A, and the frictional voltage of the substance B is on the positive side of that of the substance A. In the case of negative charge. The amount of charge is small for materials having a small difference in frictional voltage, and is large for large materials. Therefore, by using a rubbing cloth having a small difference in frictional voltage with the alignment film as described above, charging of the rubbing cloth can be suppressed, and the occurrence of the uneven stripe caused by the twist of hair can be suppressed.

  The apparatus for manufacturing a liquid crystal display device according to the present invention is a device for manufacturing a liquid crystal display device that performs a rubbing process on an alignment film provided on the surface of a substrate for a liquid crystal display apparatus, and is a substrate to be rubbed. And a rubbing roller for performing an alignment treatment from the surface side of the mask, the mask having conductivity and a predetermined potential. It is electrically connected to the outside.

  According to the manufacturing apparatus having the above-described configuration, a mask is placed on the surface of the substrate to be processed, and the rubbing process is performed. The charging of the rubbing cloth during the rubbing process can be suppressed, Since the alignment film surface can be uniformly rubbed, it is possible to prevent the occurrence of streaks due to static electricity.

  In addition, the liquid crystal display device manufacturing apparatus according to the present invention employs a configuration in which a ground potential (GND) is used as a predetermined potential when the mask is electrically connected to the outside so as to have a predetermined potential. Is preferable, and thereby the charging of the rubbing cloth can be further suppressed.

  In addition, the liquid crystal display device manufacturing apparatus according to the present invention preferably employs a configuration in which the electrode of the substrate is provided so as to be electrically connectable so as to have the same potential as the mask. Charging of the rubbing cloth can be suppressed.

  In addition, the liquid crystal display device manufacturing apparatus according to the present invention preferably employs a configuration in which the rubbing roller is provided so as to be electrically connectable so as to have the same potential as the mask. The charging of the cloth can be suppressed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view of a liquid crystal display device according to the present invention. FIG. 2 is a schematic explanatory view of a rubbing apparatus for rubbing an alignment film in the method for manufacturing a liquid crystal display device according to the present invention. FIG. 3 is an explanatory diagram for explaining a mask opening and a rubbing direction in the method of manufacturing a liquid crystal display device according to the present invention. FIG. 3A shows a rubbing direction and pixel to the alignment film in a TFT (Thin Film Transistor) substrate, and FIG. 3B shows a rubbing direction and pixel to the alignment film in a CF (Color Filter) substrate. FIG. 3C shows the relationship of the rubbing direction in the pixel when the TFT substrate and the CF substrate are bonded together. FIG. 4 is an explanatory diagram for explaining another embodiment of the mask opening and the rubbing direction in the method of manufacturing a liquid crystal display device according to the present invention. 4A shows the rubbing direction and pixel for the alignment film in the TFT substrate, FIG. 4B shows the rubbing direction and pixel for the alignment film in the CF substrate, and FIG. 4C shows the TFT. The relationship of the rubbing direction in the pixel when both the substrate and the CF substrate are bonded is shown.

  First, a schematic configuration of a liquid crystal display device manufactured after being rubbed in the present embodiment will be described. In this liquid crystal display device, as shown in FIG. 1, a liquid crystal 8 is sandwiched between a pair of transparent upper and lower substrates 1 and 2 that face each other. The filter layer 7, the counter electrode 3, and the alignment film 5 are included, and the other substrate 2 has a pixel electrode 4 and an alignment film 6. Further, the electrodes on the substrate are specifically composed of signal electrode lines, scanning electrode lines and their connection terminals on the TFT substrate, and counter electrodes on the CF substrate.

  The rubbing treatment apparatus of the liquid crystal display device according to this embodiment performs an alignment film rubbing treatment on a substrate before the substrates are bonded as shown in FIG. As shown in FIG. 2, the rubbing apparatus includes a stage 10 on which a glass substrate 1 or 2 of a TFT substrate or a CF substrate on which a vertical alignment film is previously applied can be placed, and the glass substrate 1. , 2, and a mask 9 provided with an opening corresponding to each pixel, and a rubbing roller 11 for rubbing the alignment film from the surface side of the mask 9.

  The rubbing roller 11 includes a roller main body 11a that is rotatably provided and a rubbing cloth 11b that is wound around the roller main body 11a. Thus, the rubbing roller 11 is moved close to the stage side and rotated during rubbing, so that the rubbing cloth 11b rubs the alignment film surface. For example, nylon can be used as the rubbing cloth 11b.

  The stage 10 is provided so as to be horizontally movable relative to the rubbing roller 11, and the rubbing roller 11 moves in a tangential direction on the alignment film surface by moving the stage 10 during the rubbing process. The alignment film surface is configured to be rubbed.

  The mask 9 is made of a conductive thin plate such as a copper plate having a thickness of about 100 μm. The mask 9 is provided so that it can be electrically connected to the stage 10, the electrode formed on the substrate to be rubbed, and the rubbing roller 11 to have the same potential. The electrical connection is grounded, and the potentials of these members are all set to the ground potential.

  Next, a rubbing treatment method (manufacturing method) of the liquid crystal display device using the above-described manufacturing apparatus will be described.

  First, the substrate 1 to be processed is placed on the stage 10, and the mask 9 is placed on the surface of the substrate 1. Then, the electrodes of the substrate 1 and the mask 9 are electrically connected so as to have the same potential. Then, the rubbing roller 11 is brought close to the substrate 1, the rubbing roller 11 is rotated, and the stage 10 is relatively moved to perform a desired rubbing process on the alignment film exposed from the opening of the mask 9. Apply.

  After this process, the mask 9 is moved to change the position of the opening, and the rubbing process as described above is performed again on the alignment films at different locations on the same substrate 1. Thereby, a rubbing process in a different rubbing direction is performed for each region.

  A similar rubbing process is performed on the counter substrate of the substrate 1. Here, processing is performed so that the rubbing direction of each substrate is as follows.

  That is, as shown in FIG. 3A, the rubbing direction in the pixel of the TFT substrate is divided into four regions A, B, C, and D, and four pixels A, B, C, and D of each pixel. The region is rubbed in the direction of the arrow in the figure, which forms an angle of 45 degrees with the signal electrode line. That is, since the rubbing process is performed on each of the A, B, C, and D alignment processing regions divided into the four regions, the number of times of rubbing is four.

  Further, the rubbing direction in the pixel of the CF substrate is shown in FIG. The rubbing process is performed on the four regions A, B, C, and D of each pixel in the direction of the arrow in the figure. That is, since the rubbing process is performed for each of the A, B, C, and D alignment processing regions divided into four regions, the number of rubbing operations is four.

  The relationship between the rubbing direction in the pixel when the two substrates are bonded together by bonding both the TFT substrate and the CF substrate on which the rubbing is performed, for example, by spreading 4 μm plastic beads on the substrate is shown in FIG. In each region, the rubbing direction is opposite between the opposing substrates. When liquid crystal having negative dielectric anisotropy is sealed between the substrates, the liquid crystal exhibits a pretilt angle in each direction in each region. The pretilt angle is 89 degrees, and the directions are the same four directions as the rubbed direction. Therefore, when a signal voltage is applied to the completed liquid crystal panel, the liquid crystal molecules are tilted in four directions.

  The liquid crystal panel is attached with polarizing plates on both sides so that the absorption axes of the polarizing plates are substantially orthogonal to each other and that one of the absorption axes is parallel to the signal electrode line. Thus, when no electric field is applied, the display is excellent in vertical alignment due to almost vertical alignment, and has a region in which liquid crystal molecules respond in four directions, so that display characteristics almost independent of the viewing angle direction can be exhibited.

  In addition, when the liquid crystal panel was created in a state where each part was not electrically connected anywhere without grounding, a large number of the streaks along the rubbing direction occurred, but grounding was performed as in this embodiment. When it did, the said uneven stripe did not generate | occur | produce but the uniform display was able to be obtained.

  Note that the present invention is not limited to the above-described embodiment, and the design can be changed as appropriate within the range intended by the present invention.

  That is, although a copper mask is used in the present embodiment, the present invention is not necessarily limited to this, and is within the range intended by the present invention as long as it has conductivity.

  In the present embodiment, the rubbing cloth made of nylon is used, but the present invention is not limited to this. However, the rubbing cloth is preferably subjected to a rubbing treatment using a rubbing cloth having a small difference in frictional voltage with the alignment film.

  In addition, the mask opening shape and the rubbing direction in FIG. 3 of the present embodiment are not necessarily limited thereto, and for example, the design shown in FIG. 4 can be appropriately changed. In the example shown in FIG. 4, the TFT substrate is divided into two regions along one direction, and a rubbing process is performed in each region in the opposite direction and in parallel with the one direction. The region is divided into two regions along the orthogonal direction orthogonal to each other, and the rubbing process is performed in the opposite direction and in the orthogonal direction in each region. In addition, even in the case shown in FIG. 4, the alignment state shown in Patent Document 2 could be realized without unevenness.

  Furthermore, although the mask 9 has been described as adopting a configuration in which the mask 9 is electrically connected to the electrode, the stage 10 and the rubbing roller 11 and grounded, the present invention is not limited to this. Absent. For example, by electrically connecting the mask 9 to an electrode on the substrate without grounding as in the above embodiment, the mask 9 and the electrode on the substrate have the same potential, and the rubbing cloth is charged. A certain effect of suppressing can be obtained. In addition, the mask 9 and the electrode on the substrate are not directly connected but can be indirectly connected by grounding them.

It is sectional drawing of the liquid crystal display device which concerns on this invention. It is a schematic explanatory drawing of the rubbing apparatus which performs rubbing to the alignment film in the manufacturing method of the liquid crystal display device which concerns on this invention. It is a figure which shows the mask opening part and rubbing direction in the manufacturing method of the liquid crystal display device which concerns on this invention. (A) shows the rubbing direction and pixel for the alignment film in the TFT substrate, (b) shows the rubbing direction and pixel for the alignment film in the CF substrate, and (c) shows both the TFT substrate and the CF substrate. The relationship of the rubbing direction in the pixel when the substrates are bonded is shown. It is explanatory drawing for demonstrating the other Example of the mask opening part and rubbing direction in the manufacturing method of the liquid crystal display device which concerns on this invention. (A) shows the rubbing direction and pixel for the alignment film in the TFT substrate, (b) shows the rubbing direction and pixel for the alignment film in the CF substrate, and (c) shows both the TFT substrate and the CF substrate. The relationship of the rubbing direction in the pixel when the substrates are bonded together is shown.

Explanation of symbols

1, 2... Substrates (electrodes, alignment films, etc. not shown in FIG. 2)
DESCRIPTION OF SYMBOLS 3 ... Counter electrode 4 ... Pixel electrode 5, 6 ... Alignment film 7 ... Color filter 8 ... Liquid crystal 9 ... Mask 10 ... Stage 11 ... Rubbing roller 110 ... Rubbing cloth A, B, C, D ... Orientation process area | region

Claims (11)

A method of manufacturing a liquid crystal display device in which an alignment film is provided on a pair of opposing substrates,
A mask having conductivity and provided with an opening is placed on the surface of the substrate,
In a state where the mask is electrically connected to the outside so as to have a predetermined potential,
A manufacturing method of a liquid crystal display device, characterized in that an alignment process is performed by performing a rubbing process. A method of manufacturing a liquid crystal display device according to claim 1,
The method for manufacturing a liquid crystal display device, wherein the alignment film is a vertical alignment film in which liquid crystal molecules are generally aligned in a substrate normal direction. A method of manufacturing a liquid crystal display device according to claim 1 or 2,
A method of manufacturing a liquid crystal display device, wherein at least two different alignment regions are formed in one pixel when performing an alignment process on the alignment film. A method for manufacturing a liquid crystal display device according to any one of claims 1 to 3,
The method of manufacturing a liquid crystal display device, wherein the predetermined potential is a ground potential. A method for manufacturing a liquid crystal display device according to claim 1,
A method for manufacturing a liquid crystal display device, wherein electrodes formed on a substrate to be rubbed are electrically connected so as to have the same potential as the mask. A method for manufacturing a liquid crystal display device according to claim 1,
A manufacturing method of a liquid crystal display device, wherein a rubbing roller for performing an alignment treatment on the alignment film is electrically connected so as to have the same potential as the mask.   A liquid crystal display device manufactured by the manufacturing method according to claim 1. An apparatus for manufacturing a liquid crystal display device that performs a rubbing process on an alignment film provided on a surface of a substrate for a liquid crystal display device,
A mask that can be placed on the surface side of the substrate to be rubbed and has a desired opening formed thereon, and a rubbing roller that performs an alignment process from the surface side of the mask,
The apparatus for manufacturing a liquid crystal display device, wherein the mask has conductivity and is electrically connected to the outside so as to have a predetermined potential. An apparatus for manufacturing a liquid crystal display device according to claim 8,
The apparatus for manufacturing a liquid crystal display device, wherein the predetermined potential is a ground potential. An apparatus for manufacturing a liquid crystal display device according to claim 8 or 9,
An apparatus for manufacturing a liquid crystal display device, wherein an electrode formed on the substrate is provided so as to be electrically connectable so as to have the same potential as the mask. An apparatus for manufacturing a liquid crystal display device according to any one of claims 8 to 10,
The apparatus for manufacturing a liquid crystal display device, wherein the rubbing roller is provided so as to be electrically connectable so as to have the same potential as the mask.

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