JP2006178323A - Method for manufacturing liquid crystal display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a liquid crystal display panel with which a gap between substrates is made uniform in a dropping and bonding method. <P>SOLUTION: The method for manufacturing the liquid crystal display panel includes a sealing material arranging step to arrange a sealing material on a principal surface of a TFT substrate out of the two sheets of substrates to be bonded to each other, a liquid crystal dropping step to drop a liquid crystal on the TFT substrate, a liquid arranging step to arrange a nonvolatile liquid on the TFT substrate, and a bonding step to bond the two sheets of substrates to each other. The sealing material arranging step includes a step to arrange a first sealing material in a closed frame shape and a step to arrange a second sealing material in a closed frame shape outside the first sealing material. The liquid crystal dropping step includes a step to drop the liquid crystal to a region surrounded by the first sealing material. The liquid arranging step includes a step to arrange the nonvolatile liquid on a region between the first and the second sealing materials. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a liquid crystal display panel.

  The liquid crystal display panel has a configuration in which liquid crystal is sealed between two substrates facing each other. For example, in a liquid crystal display panel, a substrate on which a pixel electrode, a driving element for driving liquid crystal, and the like are formed and a substrate on which a counter electrode that faces the pixel electrode is formed are bonded to each other at a predetermined interval. It has a configuration.

  FIG. 6 shows a schematic cross-sectional view of an example of a color liquid crystal display panel among the liquid crystal display panels. In the liquid crystal display panel 30, a TFT (Thin Film Transistor) substrate 1 and a CF (Color Filter) substrate 5 are arranged so as to face each other with an interval of several μm. A scanning line driving circuit 2 is formed on the main surface of the TFT substrate 1. In the scanning line driving circuit 2, wirings and TFTs are formed. The scanning line driving circuit 2 is connected to an external driving IC (not shown) via the terminal portion 21. A pixel electrode layer 3 is formed on the main surface of the scanning line driving circuit 2. Pixel electrodes are formed on the pixel electrode layer 3 so as to correspond to the respective pixels. An alignment film 4 is formed on the main surface of the pixel electrode layer 3.

  A color filter 6 is disposed on the surface of the CF substrate 5, and a counter electrode layer 7 and an alignment film 8 are formed on the surface of the color filter 6. The two substrates are bonded and fixed to each other by a sealing material 15. A spacer 9 is disposed between the two substrates, and a constant interval is maintained. A liquid crystal 11 is sealed in a space surrounded by the two substrates and the sealing material 15.

  As shown in FIG. 6, in the manufacture of a liquid crystal display panel, two substrates are bonded together with a sealing material so that the main surfaces thereof face each other, and liquid crystal is further formed in a region surrounded by the two substrates and the sealing material. It is necessary to enclose.

  FIG. 7 shows a flowchart of a drop bonding method among the conventional methods for manufacturing a liquid crystal display panel. In the drop bonding method, first, a scanning line driving circuit and a CF pattern are formed on the TFT substrate and the CF substrate, respectively. Next, after forming a pixel electrode layer or a counter electrode layer on each substrate, an alignment film is formed. The surface of the alignment film is rubbed.

  In the CF substrate, spacers are provided on the surface of the alignment film to determine the distance between the substrates. In addition, a conductive material is provided on the CF substrate for electrically connecting the electric circuit of the TFT substrate and the electric circuit of the CF substrate. In the TFT substrate, a sealing material for bonding the two substrates to the surface of the alignment film of the TFT substrate is arranged in an annular shape. At this time, the sealing material is arranged in a closed annular shape without forming an opening. Next, a predetermined amount of liquid crystal is dropped onto an area to be a display area of the TFT substrate. Liquid crystal is dropped on the surface of the alignment film surrounded by the sealing material.

  Next, these two substrates are bonded together with high positional accuracy in a vacuum atmosphere. Next, the distance between the substrates is adjusted under an atmospheric pressure atmosphere. Thereafter, the sealing material is cured to fix the two substrates together. Furthermore, a liquid crystal display panel is manufactured by connecting an external driving IC.

  In the drop bonding method, the space surrounded by the two substrates and the sealing material can be made a closed vacuum space by performing the bonding in a vacuum atmosphere. In this space, only liquid crystal is arranged without air mixing. Since the area surrounded by the sealing material including the display area in the liquid crystal display panel is in a vacuum state, the substrates are pressed against each other by atmospheric pressure by being released to the atmosphere, and the substrates are arranged at predetermined intervals. Is done. Thus, in the drop bonding method, the two substrates can be bonded to each other and the liquid crystal can be sealed at the same time.

  However, in the drop bonding method, the outer region where the sealing material is disposed is open to the atmospheric pressure even between the substrates, so that the force for pressing the substrates does not apply, and the force for pressing the substrates together Becomes weaker. For this reason, in the display area, there has been a problem that the cell thickness (thickness of the portion in which the liquid crystal is sealed) deviates from the design value.

  Japanese Patent Application Laid-Open No. 11-326922 discloses a method for manufacturing a liquid crystal display panel in which sealing materials are arranged in duplicate and bonding is performed with the space between the sealing materials in a reduced pressure state. FIG. 8 is a schematic sectional view for explaining the arrangement of the sealing material disclosed in this publication.

  FIG. 8 is a schematic cross-sectional view when two substrates are bonded together. A display region 40 is formed on the TFT substrate 1, and the first sealing material 16 is disposed so as to surround the display region 40. An annular second sealing material 17 is disposed outside the first sealing material 16 so as to surround the first sealing material 16.

  The liquid crystal is disposed inside the first sealing material 16. The bonded substrate is cut along the cutting line 45b, and the liquid crystal display panel is formed with the first sealant 16 left. With this manufacturing method, when two substrates are bonded together, the space between the first sealing material 16 and the second sealing material 17 is in a reduced pressure state, and the first sealing material 16 is caused by atmospheric pressure. In the region in the vicinity of the substrate, the substrate is more closely attached. For this reason, it is disclosed that a stable seal gap can be formed in the first sealing material 16 and a liquid crystal display panel having excellent quality with respect to the periphery of the display region can be realized.

  In Japanese Patent Laid-Open No. 2001-174829, a first seal and a second seal are disposed so as to enclose the first seal, and are bonded together in a vacuum atmosphere. A manufacturing method of a liquid crystal display panel is disclosed in which two seals are cured and left for a certain period of time in an atmospheric pressure atmosphere, and then the first seal is cured. According to this manufacturing method, the second seal (auxiliary seal) can be cured immediately after the dropping step of the liquid crystal, whereby the degree of vacuum in the liquid crystal display panel can be maintained at a high level for a long time. it can. For this reason, it is disclosed that in the cap uniformizing step, both substrates can be sufficiently pressurized by atmospheric pressure, and a uniform gap can be obtained over the entire display portion including the peripheral portion of the display portion.

Further, Japanese Patent Application Laid-Open No. 2002-122871 discloses a method for manufacturing a liquid crystal display panel in which a main seal surrounding a display area and a double auxiliary seal are formed in an outer area. In this manufacturing method, a reduced pressure region closed by a double auxiliary seal and an atmospheric region surrounded by the main seal and the auxiliary seal are formed. It is disclosed that the region where the substrate is raised by the reaction of the substrate being depressed by the pressing force in the decompression region stops in the atmospheric region, and the flatness of the substrate is ensured in the display region.
JP-A-11-326922 JP 2001-174829 A JP 2002-122871 A

  In the above-mentioned patent document, a plurality of sealing materials are arranged, and a pressure-reduced region is further formed around the sealing material surrounding the display region to increase the pressure for attaching the two substrates to each other. Is. In order to increase the force for bonding the two substrates together, it is preferable to increase the above-mentioned reduced pressure region.

  Further, referring to FIG. 8, a terminal portion 21 is formed on the side of the first sealing material 16. Since the driving IC or the like is connected to the terminal portion 21, the second sealing material 17 cannot be formed on the surface of the terminal portion 21. For this reason, the space | interval of the 2nd sealing material 17 and the 1st sealing material 16 must be enlarged.

  FIG. 9 shows a schematic cross-sectional view when the first sealing material 16 and the second sealing material 17 are arranged as the sealing materials and the two substrates are bonded to each other. FIG. 9 is a schematic cross-sectional view when two substrates are bonded together so that the space between the first sealing material 16 and the second sealing material 17 is a reduced pressure region. In the bonded substrate, the liquid crystal 11 is arranged inside the first sealing material 16 and arranged on a mounting table (not shown). A vacuum layer 47 is formed between the first sealing material 16 and the second sealing material 17. By releasing to the atmosphere after bonding, a force is applied to the bonded substrates so that the two substrates indicated by arrows 51 are pressed against each other.

  Here, if the area of the vacuum layer 47 is large (if the distance between the first sealing material 16 and the second sealing material 17 is large), the force for bonding the two substrates is increased. However, in the vicinity of the first sealing material 16, one substrate (CF substrate 5 in FIG. 9) or both substrates may be bent. In FIG. 9, the distance C is smaller than the distance A due to the force in the vacuum layer 47. At this time, there arises a problem that the distance B in the vicinity of the first sealing material 16 becomes larger than the distance A due to the moment of force with the first sealing material 16 as a fulcrum.

  Due to the curvature of the substrate, the distance (cell thickness) between the two substrates becomes non-uniform in the region filled with the liquid crystal 11, and as a result, in the display region formed inside the first sealing material. However, the cell thickness may be non-uniform. As a result, there is a problem that display unevenness occurs in the video and the like, and the display quality is deteriorated. In particular, there is a problem that display quality is deteriorated in the peripheral portion of the display area. Such a curvature of the substrate becomes conspicuous when a slightly larger amount of liquid crystal is dropped in consideration of variations in the amount of liquid crystal dropped into the display region.

  Further, in order to prevent the distance between the substrates from being narrowed or widened, it is conceivable to arrange photo spacers or the like between the substrates, but at each position, photo spacers having different heights are arranged. It is not practical because it needs to be formed.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method for manufacturing a liquid crystal display panel that can make the distance between the substrates uniform in the drop bonding method. .

  In order to achieve the above object, a manufacturing method of a liquid crystal display panel according to the present invention includes a sealing material arrangement in which a sealing material is arranged on the main surface of one or both of two substrates to be bonded to each other. A liquid crystal dropping step of dropping a liquid crystal on one of the two substrates, a liquid disposing step of disposing a non-volatile liquid on one of the two substrates, A liquid crystal display panel manufacturing method including a bonding step of bonding the two substrates to each other, wherein the sealing material arranging step includes a step of arranging a first sealing material in a closed frame shape; And disposing a second sealing material in a closed frame shape outside the one sealing material. The liquid crystal dropping step includes a step of dropping the liquid crystal in a region surrounded by the first sealing material, and the liquid arranging step is a region sandwiched between the first sealing material and the second sealing material. Including the step of disposing the non-volatile liquid. By adopting this method, it is possible to provide a method of manufacturing a liquid crystal display panel that can make the distance between the substrates uniform in the drop bonding method.

  In the present invention, preferably, the liquid crystal or silicon oil is used as the nonvolatile liquid. By using the liquid crystal as the non-volatile liquid, the manufacturing method according to the present invention can be performed using a conventional liquid crystal dropping device. Alternatively, the production method of the present invention can be performed at low cost by using the silicon oil as the non-volatile liquid.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the liquid crystal display panel which can make the space | interval of board | substrates uniform in the drop bonding method can be provided.

  A method for manufacturing a liquid crystal display panel according to an embodiment of the present invention will be described with reference to FIGS.

  FIG. 6 shows a schematic cross-sectional view of an example of a color liquid crystal display panel among the liquid crystal display panels. The liquid crystal display panel 30 includes a TFT substrate 1 and a CF substrate 5 as two substrates. In the present invention, in addition to a single substrate such as a glass substrate, a substrate having a pixel electrode layer or an alignment film formed on the single substrate is referred to as a “substrate”.

  The liquid crystal 11 is sealed between the TFT substrate 1 and the CF substrate 5. A scanning line driving circuit 2 is formed on the main surface of the TFT substrate 1. The scanning line driving circuit 2 is formed with wirings for electrical connection with the outside and TFTs as driving elements. The TFT is formed so as to correspond to each pixel. One end of the scanning line driving circuit 2 is connected to the terminal portion 21. The terminal portion 21 is disposed outside the sealing material 15. For example, a TCP (Tape Carrier Package) in which a drive IC (not shown) is formed is connected to the terminal portion 21 (not shown).

  A pixel electrode layer 3 is formed on the main surface of the scanning line driving circuit 2. In the pixel electrode layer 3, pixel electrodes are arranged in the display area. The display area is an area for displaying images and videos. One pixel electrode is formed for each pixel. An alignment film 4 is formed on the main surface of the pixel electrode layer 3.

  A color filter 6 is formed on the main surface of the CF substrate 5. The color filter 6 has hues of three colors of red, green, and blue so as to correspond to the respective pixels. A counter electrode layer 7 is formed on the main surface of the color filter 6. An alignment film 8 is formed on the main surface of the counter electrode layer 7. The liquid crystal 11 is filled so as to be sandwiched between two substrates, and a sealing material 15 is disposed on the side of the liquid crystal 11. The sealing material 15 is formed in a closed frame shape when seen in a plan view. In the present embodiment, the planar shape of the sealing material 15 is formed to be a substantially square shape.

  The distance between the alignment film 4 and the alignment film 8 is kept constant by sandwiching the spacer 9. That is, the distance between the two substrates is determined by the spacer 9. The two substrates are bonded and fixed to each other by a sealing material 15.

  FIG. 1 shows a flowchart of a method for manufacturing a liquid crystal display panel in the present embodiment. 2 to 5 show schematic cross-sectional views of the manufacturing method of the liquid crystal display panel in the present embodiment. In FIGS. 2 to 5, description of the CF, the pixel electrode, the alignment film, and the like is omitted for simplification of the drawings.

  Referring to FIGS. 1 and 6, in the TFT substrate, scanning line driving circuit 2 is formed on the surface of the glass substrate. Next, the pixel electrode layer 3 is formed on the surface of the scanning line driving circuit. The pixel electrode layer 3 is formed so that the pixel electrode corresponds to each pixel. Next, the alignment film 4 is formed on the surface of the pixel electrode layer 3. A rubbing process is performed on the surface of the alignment film to determine the direction in which the liquid crystal should be aligned. A terminal portion 21 is formed outside the region where the first sealing material is to be disposed.

  Referring to FIGS. 1 and 6, in CF substrate 5, counter electrode layer 7 is formed after color filter 6 is formed on the surface of a substrate such as a glass substrate. Next, an alignment film 8 is formed on the surface of the counter electrode layer 7. The surface of the alignment film 8 is rubbed to determine the direction in which the liquid crystal should be aligned.

  Next, a spacer 9 is disposed on the CF substrate 5. In the arrangement of the spacers 9, the spacers 9 are dispersed so as to be arranged in the region inside the first sealing material. In the present embodiment, granular spacers are arranged. However, the present invention is not limited to this, and for example, columnar spacers may be formed on the CF substrate.

  Next, a conductive material for electrically connecting the electric circuit formed on the TFT substrate and a part of the electric circuit formed on the CF substrate to each other is disposed on the CF substrate 5 (not shown).

  Next, referring to FIG. 1 and FIG. 2, a sealing material arrangement process is performed in which a first sealing material 16 and a second sealing material 17 are arranged on the surface of the TFT substrate 1. The first sealing material 16 is arranged so as to surround the display area. Further, the first sealing material 16 is disposed so as to have a closed frame shape when seen in a plan view. On the outside of the first sealing material 16, a second sealing material 17 is disposed along the first sealing material 16. The second sealing material 17 is arranged in a closed frame shape when seen in a plan view. The first sealing material 16 corresponds to the sealing material 15 of the liquid crystal display panel 30 in FIG.

  Next, with reference to FIG. 1 and FIG. 3, the liquid crystal 11 is disposed on the surface of the TFT substrate 1 inside the first sealing material 16 by dropping. The dropping amount of the liquid crystal 11 is adjusted to correspond to the volume surrounded by the TFT substrate 1, the CF substrate 5 to be bonded and fixed later, and the first sealing material 16. The dripping of the liquid crystal 11 may be performed at one place or at a plurality of places. Thus, a liquid crystal dropping process is performed.

  Further, a liquid disposing step of disposing the non-volatile liquid 12 in a region sandwiched between the first sealing material 16 and the second sealing material 17 on the surface of the TFT substrate 1 is performed. The non-volatile liquid 12 is selected from a material that does not volatilize even in a vacuum atmosphere where bonding is performed. The dropping amount of the nonvolatile liquid 12 is adjusted so as to correspond to the volume of the space surrounded by the TFT substrate 1, the CF substrate 5 to be bonded and fixed later, the first sealing material 16, and the second sealing material 17. ing.

  As the non-volatile liquid, for example, liquid crystal or silicon oil is preferable. By using liquid crystal as the non-volatile liquid 12, the manufacturing method in the present invention can be performed using an existing liquid crystal dropping device. Further, by using silicon oil as the non-volatile liquid 12, the production method of the present invention can be performed using a general-purpose liquid without wasting a rare liquid crystal.

  Next, referring to FIG. 1, the TFT substrate 1 on which the liquid crystal 11 and the non-volatile liquid 12 are arranged and the CF substrate 5 are bonded together under a reduced pressure atmosphere. The liquid crystal 11 is sealed in a space surrounded by the TFT substrate 1, the CF substrate 5, and the first sealing material 16. The nonvolatile liquid 12 is sealed in a space surrounded by the TFT substrate 1, the CF substrate 5, the first sealing material 16, and the second sealing material 17. Next, the second sealing material 17 is temporarily cured. This temporary curing need not be particularly performed.

  Next, referring to FIGS. 1 and 4, the two substrates bonded together are placed in an atmospheric pressure atmosphere. That is, the atmosphere is released. By arranging it under an atmospheric pressure atmosphere, an atmospheric pressure is applied as indicated by an arrow 51, for example. In addition to the region in which the liquid crystal 11 including the display region is enclosed, the force for bonding the two substrates to each other by atmospheric pressure is also applied in the region in which the nonvolatile liquid 12 is enclosed. In other words, substantially the same pressure (action) is uniform in a region (region D) surrounded by the first sealing material 16 and a region (region E) sandwiched between the first sealing material and the second sealing material. To be applied.

  Since the liquid crystal 11 is sealed in the region D and the non-volatile liquid 12 is sealed in the region E, the balance of the reaction force against the atmospheric pressure (action) becomes the same in the region D and the region E. It is possible to suppress the substrate from bending due to a pressure difference. In particular, the substrate can be prevented from bending with the first sealing material as a fulcrum. As a result, the gap thickness in the region surrounded by the first sealing material can be made uniform.

  In this way, by encapsulating the non-volatile liquid between the first sealing material 16 and the second sealing material 17, it is possible to suppress the TFT substrate 1 or the CF substrate 5 from being bent. In particular, in the vicinity of the first sealing material 16, the substrate can be prevented from being bent so as to wave, and the cell thickness in the region surrounded by the first sealing material 16 can be made uniform. As a result, the cell thickness can be made uniform even in the display area, and deterioration of display quality can be prevented.

  Next, referring to FIG. 1, main curing is performed to completely cure the first sealing material and the second sealing material. For example, when an ultraviolet curable resin is used as the sealing material, the sealing material is irradiated with ultraviolet rays.

  Next, referring to FIG. 1 and FIG. 4, the respective substrates are cut along the lines indicated by the cutting lines 45 a, 45 b, 46. A terminal portion (not shown) is formed on the surface of the TFT substrate 1 at the end on the right side in FIG. For this reason, in the part in which the terminal part is formed, the TFT substrate 1 is cut along the cutting line 45b along the terminal part. Further, the CF substrate 5 is cut along the cutting line 45 a so as to be along the first sealing material 16 outside the first sealing material 16. In the portion where the terminal portion is not formed, each substrate is cut along the first sealing material 16 as indicated by a cutting line 46.

  Next, as shown in FIG. 1, the liquid crystal display panel from which the substrate has been cut is washed to remove the non-volatile liquid. For example, when silicon oil is used as the non-volatile liquid, cleaning is performed to remove the silicon oil. By dividing and cleaning the substrate, as shown in FIG. 5, the second sealing material is removed, and a liquid crystal display panel in which only the first sealing material 16 is disposed can be formed. In addition, a liquid crystal display panel in which the distance between the two substrates is uniform can be formed.

  Thereafter, a driving IC or the like is connected to the terminal portion formed on the TFT substrate 1. Further, the manufactured liquid crystal display panel is arranged in a housing or the like to manufacture a liquid crystal display device.

  As described above, in the present invention, the step of dropping the liquid crystal in the region surrounded by the first sealing material includes a non-volatile liquid in the region sandwiched between the first sealing material and the second sealing material. Including the step of arranging. By adopting this method, it is possible to prevent the two substrates from being bent, and to provide a liquid crystal display panel having a uniform cell thickness in the display region.

  In this embodiment mode, the first sealing material, the second sealing material, and the liquid crystal are arranged with respect to the TFT substrate. However, the present invention is not limited to this mode, and any one of the substrates bonded to each other can be used. A sealant and a liquid crystal may be disposed on one substrate.

  In the present embodiment, a single color liquid crystal display panel has been described as an example of the liquid crystal display panel. However, the present invention is not limited to this embodiment, and the present invention can be applied to, for example, a monochrome liquid crystal display panel. Can do.

  Further, in this embodiment, the method for manufacturing one liquid crystal display panel has been described as an example. However, the present invention is not limited to this method, and a plurality of liquid crystal display panels are formed and bonded to a large substrate. The present invention can also be applied to a so-called multi-chamber manufacturing method in which individual liquid crystal display panels are manufactured by dividing a large substrate. In the manufacturing method by multi-chamfering, a double sealing material is arranged in each cell, and a non-volatile liquid is arranged in a region sandwiched between the sealing materials. In the step of cutting the substrate shown in FIG. 4, the large substrate is divided into individual liquid crystal display cells.

  In addition, the said embodiment disclosed this time is an illustration in all the points, Comprising: It is not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and includes all modifications within the scope and meaning equivalent to the terms of the claims.

3 is a flowchart of a method for manufacturing a liquid crystal display panel according to the present invention. It is 1st process explanatory drawing of the manufacturing method of the liquid crystal display panel based on this invention. It is 2nd process explanatory drawing of the manufacturing method of the liquid crystal display panel based on this invention. It is 3rd process explanatory drawing of the manufacturing method of the liquid crystal display panel based on this invention. It is 4th process explanatory drawing of the manufacturing method of the liquid crystal display panel based on this invention. It is a schematic sectional drawing of a color liquid crystal display panel. It is a flowchart of the drop bonding method among the manufacturing methods of the liquid crystal display panel based on a prior art. In a dropping bonding method, it is a schematic sectional view when a sealing material is disposed twice and substrates are bonded together. It is a schematic sectional drawing explaining the problem of the drop bonding method based on the prior art.

Explanation of symbols

  1 TFT substrate, 2 scanning line driving circuit, 3 pixel electrode layer, 4,8 alignment film, 5 CF substrate, 6 color filter, 7 counter electrode layer, 9 spacer, 11 liquid crystal, 12 non-volatile liquid, 15 sealing material, 16 1st sealing material, 17 2nd sealing material, 21 terminal part, 30 liquid crystal display panel, 40 display area, 45a, 45b, 46 cutting line, 47 vacuum layer, 51 arrow.

Claims (2)

A sealing material disposing step of disposing a sealing material on the main surface of one or both of the two substrates to be bonded to each other;
A liquid crystal dropping step of dropping a liquid crystal on one of the two substrates;
A liquid disposing step of disposing a non-volatile liquid on one of the two substrates;
A method of manufacturing a liquid crystal display panel, comprising a bonding step of bonding the two substrates to each other,
The sealing material arranging step includes arranging a first sealing material in a closed frame shape;
Disposing a second sealing material in a closed frame shape outside the first sealing material,
The liquid crystal dropping step includes a step of dropping the liquid crystal in a region surrounded by the first sealing material,
The liquid disposing step includes a step of disposing the non-volatile liquid in a region sandwiched between the first sealing material and the second sealing material.   The method for manufacturing a liquid crystal display panel according to claim 1, wherein the liquid crystal or silicon oil is used as the nonvolatile liquid.

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