JP2009163207A - Liquid crystal display and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display capable of restraining a liquid crystal material from contaminated with an impurity eluted out of a seal material, capable of restraining an adhesive strength of the seal material from getting low, and capable of enhancing a display quality and reliability of the liquid crystal display, and a manufacturing method therefor. <P>SOLUTION: This liquid crystal display 1 having a TFT substrate 2 and a CF substrate 3 bonded with the closed-curved-line-like seal material 5 surrounding a pixel area, and sandwiched with the liquid crystal material 4 in an area surrounded by the seal material 5 between the TFT substrate 2 and the CF substrate 3, has a frame area in an outer circumferential side of the pixel area and in an inner circumferential side of the closed-curved-line-like seal material 5, and is constituted to form a film face contacting with a frame BM6 in the frame area of the CF substrate 3 and/or the liquid crystal material 4 of an organic film or an inorganic film in the frame area of the TFT substrate 2, into a rough face shape 11 having surface roughness more rough than that of a film face contacting with the liquid crystal material 4 in the pixel area. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device and a manufacturing method thereof.

  FIG. 12 is a cross-sectional view showing a structure in the vicinity of a frame of a conventional liquid crystal display panel. The liquid crystal display panel 1 includes a TFT substrate 2 on which switching elements such as thin film transistors (TFTs) are formed in a matrix, and a CF substrate on which a color filter (CF), a black matrix (BM), and the like are formed. 3 and an alignment film 9 subjected to an alignment process is formed on the opposing surfaces of these substrates. Then, in order to form a predetermined gap (gap) between the two substrates, the column spacer 10 and the sealing material 5 are formed, and the liquid crystal material 4 is sealed in the gap.

  FIG. 13 shows a flow of a conventional liquid crystal display panel bonding process. In the seal application process, a sealant is applied to a predetermined position of the TFT substrate to form the outer peripheral (auxiliary) seal and the main seal in an uncured state. Subsequently, in the Ag application process, the Ag transfer is applied to the TFT substrate at a predetermined position. It was applied in the form of dots at the position (when a TN (Twisted Nematic) mode liquid crystal display panel was produced). Next, in the liquid crystal dropping step, the liquid crystal material was dropped at a predetermined drop amount in a matrix shape, a linear shape, or a radial shape at a predetermined position inside the main seal.

  Next, column spacers or spherical spacers for forming a predetermined gap between the substrates are arranged in advance in the pixel region of the CF substrate, and the substrates are brought into contact with each other and pressed in the bonding step. The gap between the substrates was formed uniformly while the liquid crystal material was uniformly diffused throughout the pixel region.

  And in order to prevent the fitting shift | offset | difference of a bonding board | substrate at the time of conveyance to the next process, UV temporary hardening of several places was performed partially as temporary fixing of a sealing material. At this time, the liquid crystal material diffused rapidly with time, passed from the pixel region through the outer frame BM formation portion to the seal material, and was in contact with the seal material. In the next UV curing step, the sealing material was cured by UV irradiation (at this time, the sealing material was in a semi-cured state). In the conventional method, the uncured sealing material and the liquid crystal material are in contact with each other for a long time until the UV curing step is completed. Furthermore, in the next thermosetting step, the sealing material was completely cured, but at this time, the initial semi-cured sealing material and the liquid crystal material were kept in contact with each other.

  As described above, in the conventional structure, the uncured or semi-cured sealing material and the liquid crystal material come into contact with each other in the bonding process, the UV curing process, or the thermosetting process, as shown in FIG. As a result, a large amount of impurities such as elution from the sealing material 5 to the liquid crystal material 4 causes a problem of contaminating the liquid crystal material 4. Examples of substances that contaminate the liquid crystal material 4 include oligomer components that dissolve from the uncured or semi-cured sealing material 5, organic substances such as phthalates, and ionic impurities such as Na, K, and Cl. Further, the liquid crystal material 4 comes into contact with the uncured or semi-cured sealing material 5, and the liquid crystal material 4 erodes the interface between the sealing material 5 and its base, so that the substrate interface to which the sealing material 5 is applied is applied. There has been a problem that the seal adhesive strength is lowered at the portion. As a result, problems such as spots, unevenness, and peeling of the seal occur in the periphery of the seal of the liquid crystal display panel after the reliability test, causing problems in display quality and reliability of the liquid crystal display device.

  As a technique for solving the problem of contamination of the liquid crystal material caused by contact between the uncured or semi-cured sealing material and the liquid crystal material, and the problem of decrease in the adhesive strength of the sealing material, (1) a barrier was used. There are technologies and (2) technologies for increasing the surface energy.

  As shown in FIG. 14, the technique using the barrier (1) technique forms a convex portion 12 between the pixel region of the TFT substrate 2 and the region to which the sealing material 5 is applied, and the convex portion 12 The diffusion of the liquid crystal material 4 is suppressed by adjusting the distance from the CF substrate 3 facing the convex portion 12 to be narrow. As conventional examples related to this method, there are JP-A-11-38424 and JP-A-2003-315810. In JP-A-11-38424, the pixel region of the TFT substrate and the region where the sealing material 5 is applied. It is disclosed that a convex portion 12 is formed on the top and a vertical alignment film is formed on the top of the convex portion 12 as an alignment film. Japanese Patent Laid-Open No. 2003-315810 discloses that a large number of flow control walls 13 of the liquid crystal material 4 are formed in the pixel region or in the pixel region and outside the pixel region, as shown in FIG.

  As a conventional example relating to the technique for increasing the surface energy of (2), there is JP-A-10-260406. In this publication, the orientation of the display region is modified by surface modification of the alignment film at a position away from the display region. It discloses that the surface energy is higher than that of the film.

JP 11-38424 A JP 2003-315810 A JP-A-10-260406

  However, in Japanese Patent Application Laid-Open No. 11-38424, the convex portion for directly stopping the flow of the liquid crystal material is formed so that the gap between the convex portion and the substrate opposite to the substrate is extremely small. Although the problem is solved to some extent, no consideration is given to the deterioration of the gap uniformity at the periphery of the seal due to the formation of the liquid crystal stopper. That is, the suppression method described in the above publication is a method of controlling liquid crystal diffusion by a convex portion for directly stopping the flow of the liquid crystal material, and controlling by the height of the convex portion. For this reason, in order to reduce the liquid crystal diffusion rate, it is necessary to form a convex part in the periphery of the seal with a large convex part height and in a wide range, and depending on how the convex part height varies, the substrate facing the convex part This causes a problem of local contact, and local stress is generated due to this contact, resulting in gap variations in the periphery of the seal. As a result, the display quality is degraded at the boundary between the frame BM formation portion and the pixel region. This becomes more noticeable as the distance between the convex portion and the substrate becomes shorter.

  In Japanese Patent Application Laid-Open No. 2003-315810, since a large number of convex flow control walls for directly stopping the flow of the liquid crystal material are arranged, the problem of contamination of the liquid crystal material is solved to some extent. No consideration is given to the deterioration of the uniformity of the gap in the pixel region and the peripheral portion of the seal by arranging a large number of walls so as to contact the opposing substrate. That is, the suppression method according to the above publication suppresses liquid crystal diffusion by arranging a large number of convex flow control walls for directly stopping the flow of the liquid crystal material, and is controlled by the number of flow control walls arranged. Is the method. A large number of flow control walls are arranged in the pixel region or in the pixel region and outside the pixel region so as to come into contact with the substrate facing the flow control wall. This leads to gap variations. As a result, the display quality of the pixel area is lowered, and the display quality is lowered at the boundary between the frame BM formation part and the pixel area.

  Japanese Patent Laid-Open No. 10-260406 discloses that an ionic impurity in a sealant is produced after the liquid crystal display panel is manufactured by increasing the surface energy of the alignment film at a position away from the display region than the alignment film in the display region. Although the problem of contamination of the liquid crystal material due to diffusion into the material may be solved to some extent, there is no difference in that the liquid crystal material comes into contact with the uncured or semi-cured seal material. That is, in the suppression method according to the above publication, the alignment film at a position away from the display region is melted from the sealing material to the liquid crystal material after the liquid crystal display panel is manufactured by making the surface energy higher than that of the alignment film in the display region. It only adsorbs ionic impurities that have already melted out and suppresses diffusion to the liquid crystal material, but it melts in large quantities from the manufacturing process due to the contact between the uncured or semi-cured sealing material and the liquid crystal material. Ionic impurities cannot be suppressed in advance.

  The present invention has been made in view of the above problems, and its main purpose is to suppress the contamination of the liquid crystal material and the decrease in the adhesive strength of the seal material due to impurities dissolved from the seal material, and the display of the liquid crystal display device An object of the present invention is to provide a liquid crystal display device capable of improving the quality and reliability and a method for manufacturing the same.

  In order to achieve the above object, according to the present invention, a pair of opposing substrates are bonded by a closed-curved sealing material surrounding a pixel region, and a liquid crystal material is sandwiched between regions of the sealing material between the pair of substrates. In the liquid crystal display device, a film surface having a frame region on the outer peripheral side of the pixel region and the inner peripheral side of the closed curved seal material and in contact with the liquid crystal material in at least a part of the frame region of at least one substrate Is a rough surface having a larger surface roughness than the film surface in contact with the liquid crystal material in the pixel region.

  According to the liquid crystal display device and the method of manufacturing the same of the present invention, the following effects can be obtained.

  The first effect of the present invention is that contamination of the liquid crystal material and a decrease in adhesive strength of the seal material due to contact between the uncured or semi-cured seal material and the liquid crystal material can be suppressed. The reason is that a fine rough surface shape for controlling liquid crystal diffusion is formed on the surface of the film formed in the frame BM forming portion of the CF substrate and the light shielding region of the TFT substrate facing the CF substrate. This is because the surface energy of the liquid crystal material can be reduced, and as a result, the wettability with respect to the liquid crystal material can be reduced, and the liquid crystal diffusion rate can be reduced.

  The second effect of the present invention is that it is possible to provide a high-quality liquid crystal display device with improved reliability at each stage. The reason for this is that it is not necessary to shorten the distance between the CF substrate and the TFT substrate in the frame BM formation portion, so that the required liquid crystal diffusion speed can be obtained without deteriorating the gap uniformity in the vicinity of the frame BM. Because you can. This is also an effective means for a liquid crystal display device having a product design in which the sealing material and the liquid crystal material are easy to contact, such as a narrow frame structure or high-speed response.

  As shown in the background art, since the diffusion of the liquid crystal material cannot be controlled in the bonding process, the UV curing process or the thermosetting process, the liquid crystal material comes into contact with the uncured or semi-cured sealing material. There has been a problem of contamination of the liquid crystal material and a decrease in the adhesive strength of the seal. Therefore, in the present invention, a rough surface shape for controlling liquid crystal diffusion is formed on the surface of the film formed on the outer peripheral side of the pixel region and the inner peripheral side of the sealing material application region, and is in contact with the liquid crystal material. By increasing the surface area of the interface, the surface energy is lowered, that is, the wettability with respect to the liquid crystal material is lowered, and the liquid crystal diffusion rate is reduced.

  Specifically, either a CF substrate having a black matrix (frame BM) made of an organic film or an inorganic film in a frame region and a TFT substrate having an organic film or an inorganic film formed in the frame region, facing each other, or In the liquid crystal display panel in which the sealing material is applied to both sides and the liquid crystal material is sealed, the liquid crystal material caused by the contact between the liquid crystal material and the uncured or semi-cured sealing material when the liquid crystal is dropped after the liquid crystal is dropped. For the purpose of suppressing contamination and lowering of the adhesive strength of the sealing material, liquid crystal diffusion (refers to a phenomenon in which the liquid crystal material moves and spreads) on the frame BM of the CF substrate and the surface of the film of the TFT substrate facing it. A fine rough surface shape for control is provided. As a result, the sealing material can be prevented from coming into contact with the liquid crystal material in an uncured or semi-cured state, and a high-quality liquid crystal display device with improved reliability can be provided. Hereinafter, description will be given with reference to the drawings.

[Embodiment 1]
FIG. 1 is a sectional view showing the structure of a liquid crystal display panel according to a first embodiment of the present invention. The liquid crystal display panel 1 includes one substrate (hereinafter referred to as a TFT substrate 2) on which switching elements are formed in a matrix and the other substrate (hereinafter referred to as a CF substrate 3) on which a color filter, a black matrix, and the like are formed. And an organic film or an inorganic film is formed on a surface of the frame portion (peripheral portion) of the TFT substrate 2 in contact with the liquid crystal material 4, and an organic film is formed on the frame portion of the CF substrate 3. A frame BM6 made of a film or an inorganic film is formed. In addition, an alignment film 9 subjected to at least alignment treatment is formed in the pixel region on the opposing surface of these substrates. In order to maintain a predetermined gap (gap) between the opposing substrates, a column spacer 10 and a seal material 5 are formed, and a liquid crystal material 4 is sealed in the gap.

  There are two methods for encapsulating liquid crystal: the liquid crystal injection method and the liquid crystal dropping method. In the liquid crystal injection method, the sealing material has already been cured before the liquid crystal is encapsulated, whereas in the liquid crystal dropping method, the curing is complete. There is a difference that it is cured after the liquid crystal is dropped. Further, the liquid crystal injection type sealing material surrounds the pixel region, but since it is necessary to inject liquid crystal, it cannot be formed in a closed curve shape, and it is necessary to provide a hole in a part thereof. On the other hand, the liquid crystal dropping type sealing material is different in that it is formed in a closed curve shape so as to surround the pixel region. Therefore, in the case of the liquid crystal dropping method, the problem of contamination of the liquid crystal material 4 due to contact between the uncured or semi-cured seal material 5 and the liquid crystal material 4 and a decrease in the adhesive strength of the seal material 5 occurs remarkably. . Also. With the advancement of the technology of liquid crystal display devices, a frame portion that is not involved in the role of display, that is, a narrowed frame structure that narrows the space between the pixel region and the seal application position is being adopted. It is to make it.

  Therefore, in the present invention, in order to prevent contamination of the liquid crystal material 4 due to contact between the uncured or semi-cured seal material 5 and the liquid crystal material 4 and a decrease in the adhesive strength of the seal material 5, The surface of the film BM6 and the surface of the film in contact with the liquid crystal material 4 of the TFT substrate 2 opposite to the frame BM6 (hereinafter, the panel portion shielded by the frame BM6 is referred to as a light shielding portion) is finely roughened to control liquid crystal diffusion. The surface shape 11 is used. By making the film surface into the fine rough surface shape 11 in this way, it becomes possible to reduce the surface energy with respect to the liquid crystal material 4 in this portion (assuming an averaged uniform surface energy). The contact angle between the liquid crystal material 4 and the substrate is increased, and the wettability can be reduced.

  FIG. 2 shows a fine rough surface forming region. The fine rough surface shape 11 is formed between the respective pixel regions of the TFT substrate 2 and the CF substrate 3 of the liquid crystal display panel 1 and the seal application position, and more specifically, as an example, the outer peripheral region of the pixel region and the inner periphery of the seal pattern. The frame region formed by the common part of the region is formed in a closed curve shape. FIG. 3 shows an example of a fine rough surface forming region for further controlling the diffusion of the liquid crystal material. The fine rough surface shape 11 is formed in the frame area excluding the panel corner portion between the pixel area of the TFT substrate 2 and the CF substrate 3 of the liquid crystal display panel 1 and the seal application position. This is because when the position where the liquid crystal material is dropped into the pixel area is farther from the seal application position than the panel corner, the panel corner moves from the panel side to the liquid crystal seal application position. This takes into account the relatively long arrival time.

  Here, the liquid crystal display panel process flow of the present invention is shown in FIG. In the rough surface shape forming process of the CF substrate, a fine rough surface shape is formed so that the contact angle increases with respect to the outermost surface of the frame BM between the pixel region and the seal application position, that is, the film surface in contact with the liquid crystal material after the liquid crystal is sealed. Apply. In this way, a rough surface shape in a predetermined range set in consideration of the lead time from the bonding process out to the thermosetting process in is formed on the frame BM. In the case of a CF substrate on which no frame BM is formed, a fine rough surface shape may be formed on an organic film or an inorganic film in contact with a liquid crystal material between a pixel region and a seal application position. In addition, column spacers for forming a predetermined gap between the substrates are formed in advance in the pixel region of the CF substrate. However, when a CF substrate without the column spacers is used, the rough surface shape formation is completed. An insulating spherical spacer such as polymer beads or silica beads may be disposed later.

  On the other hand, in the rough surface shape forming process of the TFT substrate, the fineness is similarly reduced from the pixel region facing the rough surface shape of the CF substrate to the organic film or inorganic film surface of the TFT substrate between the seal coating positions. A rough surface shape is applied. For example, on the top surface of an organic film such as SiNx used as a gate insulating film, an inorganic film such as ITO (Indium Tin Oxide) used as a pixel electrode, or a novolak or the like for further improving the insulating properties than the SiNx. On the other hand, a fine rough surface shape is applied. In this way, a rough surface shape in a predetermined range is formed on the TFT substrate side as well as the CF substrate.

  FIG. 4 shows an example in which the rough surface shape forming process is provided as the next process of the rubbing cleaning / drying process, but before the substrate (TFT / CF) cleaning process which is the head of the panel manufacturing process. A rough surface shape forming step may be provided, or a rough surface shape may be formed in advance during an etching process for forming an insulating film or the like in the TFT manufacturing process. In other words, the rough surface shape forming process may be provided in a process upstream of the liquid crystal dropping process regardless of whether the substrate is a TFT substrate or a CF substrate.

  Next, in the seal application process, a sealant is applied to a predetermined position of the TFT substrate as an outer peripheral (auxiliary) seal and a main seal, respectively, so that at least after bonding, the main seal forms a closed curved seal pattern. Apply. Subsequently, in the Ag application process, Ag transfer is applied to a predetermined position of the substrate in a dot pattern (the Ag application process is performed when a TN mode liquid crystal display panel is manufactured, and in the IPS (In Plane Switching) mode. This process is omitted). Next, in the liquid crystal dropping step, a predetermined dropping amount is dropped at a predetermined position in any shape such as a matrix (a large number of dots in the matrix), linear or radial so that the liquid crystal material does not come into contact with the seal.

  Thereafter, in the bonding step, the TFT substrate and the CF substrate face each other and are contacted and pressed to uniformly diffuse the liquid crystal material in the pixel region and the peripheral portion between the substrates. The gap is formed uniformly. At this time, in order to provide gap uniformity in the pixel region, it is better that the liquid crystal material diffuses quickly in the pixel region. This is because the gap uniformity in the pixel region is maintained by making the liquid crystal layer in the pixel region uniform by increasing the diffusion of the liquid crystal material while the TFT substrate and the CF substrate are pressed. On the other hand, when the diffusion of the liquid crystal material is slow, the liquid crystal layer is thicker in the center of the pixel region than in the periphery of the pixel region (drum state), and gap uniformity is impaired.

  Next, in order to prevent misalignment of the bonded substrate during transport to the UV curing process, UV temporary curing may be performed at several locations on the outer peripheral seal as a temporary fixing of the sealing material. preferable. At this time, the liquid crystal material quickly diffuses in the pixel area as time passes and reaches the frame BM formation portion. In this frame area, the diffusion speed of the liquid crystal material is reduced due to the fine rough surface shape of the present invention. Decreases and does not touch the sealing material. In this state, in the next UV curing step, the sealing material is cured by a predetermined amount of UV irradiation (at this time, the sealing material is in a semi-cured state). By this liquid crystal diffusion control, it is possible to prevent the uncured sealing material and the liquid crystal material from contacting each other.

  Then, in the next thermosetting step, the sealing material is completely cured by heating at a predetermined temperature, and the required adhesive strength is obtained. At this time, since the diffusion of the liquid crystal material is continuously controlled by the fine rough surface shape of the present invention, the liquid crystal material is not in contact with the sealing material. In this way, contact between the semi-cured sealing material and the liquid crystal material can be suppressed. The viscosity of the liquid crystal material gradually decreases with heating, and when the thermosetting is completed, the entire area inside the seal is diffused and filled, the seal material and the liquid crystal material come into contact with each other, and uniformity of the gap is ensured even in the vicinity of the frame BM. The Thereafter, the manufactured liquid crystal display panel is subjected to an ACF (Anisotropic Conductive Film) pasting / TCP (Tape Carrier Package) pressure welding process and a substrate pressure welding process, and a backlight light source is attached in an assembly process, thereby completing a liquid crystal display device.

  Thus, in the present invention, the film surface of the organic film or inorganic film formed in the frame region between the pixel region of the TFT substrate 2 and the CF substrate 3 and the seal coating position is formed into a fine rough surface shape. The surface energy with respect to the liquid crystal material is reduced, the diffusion speed of the liquid crystal material passing through the frame region is decreased, and the contact between the uncured or semi-cured sealing material and the liquid crystal material can be suppressed.

  The rough surface shape may be formed on the outer side from the pixel region. In order to further improve the adhesion between the sealing material and the substrate, it is preferable that the rough surface shape is formed extending to the seal application position. Further, the rough surface shape arranged in this way may be appropriately set in width and roughness in consideration of a lead time from gap formation to sealing material curing. In addition, depending on the setting of the rough surface shape, the orientation of the liquid crystal at the portion where it is disposed may be disturbed, and a problem (for example, light leakage) may occur in the display state of the liquid crystal display device. What is necessary is just to arrange | position a shape. In addition, FIG. 1 shows an example in which a gap is provided between the frame BM and the sealing material. However, as described above, the frame BM can be extended under the sealing material as necessary.

[Embodiment 2]
FIG. 5 is a sectional view showing the structure of the liquid crystal display panel according to the second embodiment of the present invention. This liquid crystal display panel 1 is the same as the liquid crystal display panel of the first embodiment shown in FIG. 1 on the surface of the film constituting the frame BM6 and the surface of the film constituting the TFT opposite thereto, that is, the film surface in contact with the liquid crystal material. For example, a rough surface structure 11a having fine irregularities is provided at a desired position on the surface of the gate / drain / interlayer insulating film / protective film.

  The fine uneven surface structure 11a exhibits high liquid repellency. Wenzel's theory discusses the relationship between film surface roughness and wettability, but wettability decreases when the film surface is roughened. The reason why the wettability with respect to the liquid crystal material is reduced by making the film surface rough is that the area where the liquid crystal material and the film surface are in contact with each other is increased (AW Adamson, “Physical Chemistry of Surfaces (John Wiley & Sons , New York))). That is, in the present invention, as clarified by Wenzel's theory, by roughening the film surface, the surface energy is lowered, that is, the wettability with respect to the liquid crystal material is lowered, and the contact angle is increased. As described above, the diffusion rate of liquid crystal during panel bonding is reduced.

  However, even if the concavo-convex shape is simply formed to increase the surface area, the diffusion of the liquid crystal material cannot be controlled and the final diffusion of the liquid crystal material is delayed. As a result, the gap uniformity in the frame portion may be deteriorated, and therefore it is important to form the minute uneven surface structure 11a of the present invention in a closed curve shape. The correspondence will be described below.

  FIG. 6 shows an example of the shape of the rough surface structure according to the present invention. This is a schematic view of the frame portion of the liquid crystal display panel of the present invention as viewed from the cross-sectional direction and the front direction. A rough surface structure such as a columnar shape, a comb-like shape, or a hole shape is regularly or irregularly provided on the outermost surface of the frame BM of the CF substrate and the inorganic or organic film of the TFT substrate, that is, the film surface in contact with the liquid crystal material. is doing. The columnar shape is a structure with regular square micro irregularities, the comb-like shape is a structure with regular rectangular micro irregularities, and the hole shape is irregularly provided with many fine holes. This is the structure.

  By making such a rough surface structure, that is, a surface state that increases the surface area of the contact interface with the liquid crystal material, an effect of reducing the diffusion rate of the liquid crystal material passing through the frame BM can be obtained. This is because when the surface roughness of the contact interface with the liquid crystal material is increased, that is, the surface area is increased, the surface energy is decreased and the contact angle is increased as compared with a smooth surface. Further, in order to reduce the surface energy and increase the contact angle, it is only necessary to increase the surface roughness of the contact interface portion and widen the contact area as described above. At this time, the unevenness of the rough surface structure is uniform or uneven. It may be continuous.

  FIG. 7 shows the relationship between the surface roughness of the contact interface with the liquid crystal material and the contact angle in the case of a columnar rough surface structure. Here, arithmetic average roughness [Ra] / unevenness average interval [Sm] was calculated as a surface roughness parameter (Ra and Sm are based on JIS B0601-1994). When this value is large, the surface roughness of the rough surface portion is large, indicating that the surface area of the portion in contact with the liquid crystal material per unit area of 1 μm 2 in the rough surface forming region is large. FIG. 7 shows that the contact angle with the liquid crystal material increases as the surface roughness of the rough surface layer of minute irregularities per unit area increases. In addition, the rough surface layer here is a case where it is made to provide on the ITO film | membrane surface which is an inorganic film. Similarly, when applied on an organic film, the organic film has a higher liquid repellency than that of an inorganic film, so the contact angle with a liquid crystal material on a smooth surface is slightly larger. It has been confirmed that the contact angle with respect to the liquid crystal material increases as the surface roughness of the rough surface layer per unit area increases.

  FIG. 8 shows a state in which the liquid crystal material is dropped in a matrix form on the TFT substrate on which the rough surface layer of the fine irregularities is formed between the pixel region and the seal application position, that is, on the film surface in contact with the liquid crystal material (here, It is a schematic diagram showing 1 drop). The microstructure of the present invention has a surface roughness much smaller than the amount of liquid crystal material dropped (about 8 mmφ). Examples of the method for forming the rough surface layer include focused ion beam (FIB), femtosecond laser, etching, and plasma ashing.

  In the columnar and comb-like microstructures, the surface of the frame BM and the film surface of the TFT substrate facing the frame BM are etched at an equal pitch so that the structure is in the range of 0.1 to 10 μm and deep in the vertical direction. To form. For example, in the case of a columnar structure, the surface is etched in a vertical direction to a depth of 0.5 μm so that each side becomes a square column of 0.5 μm, and the columnar rough surface layer is regularly formed at a pitch of 1 μm. It can be formed. In such a columnar structure, the relationship between the width of the bottom of the column and the height of the column is set such that [height] / [width of the bottom] ≧ 1. Further, in the case of a comb-like structure, the surface becomes a deeper structure in the vertical direction up to a depth of 0.8 μm so as to be a rectangular comb having one side of 0.5 μm and the other side of 5 μm. Etching treatment can be used to regularly form a comb-like rough surface layer at a pitch of 1 μm. As described above, also in the comb-like structure, the relationship between the width of the short side of the comb teeth and the height of the comb teeth is set so that [height] / [width of the base] ≧ 1.

  In the hole-like fine structure, a large number of fine holes can be formed on the surface of the frame BM and on the film surface of the TFT substrate opposite to the frame BM by ashing. The pore diameter is 100 nm or less, has a wide pore distribution from macropores to micropores, and has a surface state that increases the surface area.

  As described above, in a columnar or comb-like microstructure, a deep structure in the vertical direction such as a large number of protrusions is formed, so that a large number of minute holes are formed in a void-shaped microstructure. Thus, the effect of reducing the surface energy can be further increased.

[Embodiment 3]
FIG. 9 is a sectional view showing the structure of a liquid crystal display panel according to a third embodiment of the present invention. This liquid crystal display panel 1 is a liquid crystal display panel according to the first embodiment shown in FIG. 1, and has a rough surface shape with respect to the surface of the frame BM6 and the film surface of the TFT substrate 2 opposed thereto, that is, the film surface in contact with the liquid crystal material. In the formation region, a rough surface layer and a liquid repellent film are sequentially formed. By forming a soot liquid crystal film on the roughened TFT substrate 2 and the CF substrate 3, the surface roughness of the liquid crystal repellent film is increased, and the liquid crystal repellency and surface roughness of the liquid crystal repellent film are synergistic. As a result, the wettability with respect to the liquid crystal material is further lowered, and an effect of further reducing the diffusion rate of the liquid crystal material passing through the frame BM can be obtained. As described above, since the diffusion rate of the liquid crystal material can be further suppressed, it can sufficiently cope with a liquid crystal display panel designed with a narrow frame structure or a liquid crystal display panel using a low viscosity liquid crystal material. I can do it.

  As the liquid repellent film, a film such as a fluorine film or a silicone film is suitable. When the film is formed with a thickness of 10 nm or more, the contact angle between each film and the liquid crystal material is not substantially changed. I have confirmed that. Furthermore, when the thickness is 100 nm or more, it has been confirmed that a stable film can be formed without any repelling or unpainted pinholes or the like, although there is no change in contact angle compared to 10 nm.

  FIG. 10 is a conceptual diagram showing the liquid crystal diffusion control effect by the rough surface shape. FIG. 10B shows the diffusion state of the liquid crystal material when the conventional substrates are bonded together. When the CF substrate and the TFT substrate are contacted and pressed, the liquid crystal material rapidly moves from the pixel region to the frame BM formation portion. To spread. As a result, the diffused liquid crystal material comes into contact with the uncured sealing material before UV curing. On the other hand, FIG. 10A shows the diffusion state of the liquid crystal material when the substrates of the present invention are bonded. Even if the CF substrate and the TFT substrate are contacted / pressurized, the light shielding portion is in contact with the liquid crystal material. Since the rough surface shape is increased so that the angle increases, the diffusion speed of the liquid crystal material is significantly reduced at the frame BM formation portion. As a result, the timing at which the liquid crystal material comes into contact with the uncured sealing material before UV curing can be delayed, and the contact between the uncured sealing material and the liquid crystal material can be suppressed.

  When the contact angle is measured based on JIS R3257-1999 “Testing method for wettability of substrate glass surface” using a liquid crystal material sealed in a liquid crystal display panel (for example, contact angle measuring machine DM300 manufactured by Kyowa Interface Science). The degree of liquid repellency can be easily confirmed. As long as the rough surface shape is formed, this liquid repellency is reproduced even if the liquid crystal display panel is disassembled and the liquid crystal material attached with acetone or IPA is removed and then measured again. Note that the contact angle with the rough liquid crystal material applied to the frame BM of the CF substrate and the film surface of the TFT substrate facing the frame BM is larger than the contact angle on the alignment film surface in the pixel region. This is because the surface roughness of the rough surface applied to the frame BM of the CF substrate and the film surface of the TFT substrate opposite thereto is a surface roughness on the surface of the alignment film which is the surface layer of the pixel region of the CF substrate and the TFT substrate. This is because it is made larger than this.

  Here, FIG. 11 shows the relationship between the liquid crystal diffusion speed and the gap in the frame BM formation portion according to the embodiment of the present invention. The X mark in the figure indicates that a rough surface layer is not formed, the △ mark indicates that only a columnar rough surface layer formed with square minute irregularities is formed, and the ○ mark indicates that a fluorine film is further formed on the columnar rough surface layer. The case where it formed is shown.

  In general, in a liquid crystal display panel, the gap between the frame BM formation portion, that is, the gap distance between the frame BM and the TFT substrate is that a color layer serving as a CF is not formed in the frame BM. large. From FIG. 11, it can be seen that the liquid crystal diffusion rate gradually decreases as the gap distance between the frame BM and the TFT substrate decreases, that is, the gap in the pixel region decreases. However, when the light shielding portion is not roughened, there is a limit to speed reduction even if the gap distance between the frame BM and the TFT substrate is considerably shortened. Therefore, if the distance is shortened so that the frame BM and the TFT substrate come into contact with each other in order to further reduce the speed, there arises a problem that the frame BM and the TFT substrate partially come into contact. As a result, the gap uniformity deteriorates at the contact point in the vicinity of the frame BM, and a new problem of peripheral unevenness occurs.

  On the other hand, the frame BM and the TFT substrate are formed by forming a columnar rough surface layer having a large surface area increase rate and forming square minute irregularities, or further forming a fluorine film on the columnar rough surface layer. It is not necessary to extremely shorten the gap distance from the gap, and it is possible to set the rough surface shape and the surface roughness according to the gap of the target pixel region or the frame BM width of the liquid crystal display panel. As a result, the required liquid crystal diffusion speed can be obtained without deteriorating the gap uniformity in the vicinity of the frame BM.

  Here, the film thickness of the film was 100 nm. As described above, the contact angle formed between the film and the liquid crystal material is approximately 10 nm or more and is a substantially constant value. Further, the width of the rough surface shape can be set within an allowable range of the frame BM width between the pixel region and the seal application position, and is preferably set in consideration of the lead time from the bonding process out to the thermosetting process in. . For example, when manufacturing a liquid crystal display panel in which the gap distance between the frame BM and the TFT substrate is 2.0 μm under the process conditions in which the lead time from the bonding process out to the thermosetting process in is within 2.5 minutes. FIG. 11 shows that, in the case of having a rough surface shape that becomes a rough surface layer on the surface of the frame BM and on the film surface of the TFT substrate facing it, the rough surface shape width is set to 4.8 mm or more in consideration of variation. Good. In this way, the uncured sealing material and the liquid crystal material do not come into contact with each other.

  In each of the above embodiments, a description has been given of an example in which both the CF substrate and the TFT substrate have a rough surface shape for controlling liquid crystal diffusion, but at least one of the CF substrate and the TFT substrate is used. When the rough surface configuration is used, the diffusion rate of the liquid crystal material can be reduced, so that the time for the liquid crystal material to contact the uncured or semi-cured seal material can be delayed, and contamination of the liquid crystal material can be prevented. Can be suppressed.

  In the following examples, specific examples of the method for producing a liquid crystal display panel of the present invention will be described. However, the present invention is not limited to the following examples unless the gist of the present invention is changed.

  First, as a first example, a method for manufacturing an IPS mode liquid crystal display device according to a second embodiment of the present invention will be described.

  In the rough surface shape forming process of the CF substrate, the surface of the frame BM between the pixel region and the seal application position is finely processed by a focused ion beam (FIB) apparatus, each side is 0.5 μm, and the depth is 0.5 μm. Then, a columnar rough surface layer ([Ra] / [Sm] = 0.25) having a pitch of 1 μm was formed in a closed curve shape around the pixel region. In addition, in a liquid crystal display panel with a gap distance between the frame BM-TFT substrate of 2.1 μm, in order to fabricate under a process condition in which the lead time from the bonding process out to the thermosetting process in is within 2 minutes, The width of the surface layer was 4.2 mm (the target value of the gap (gap) in the pixel area was 2.0 μm). On the other hand, in the rough surface shape forming step of the TFT substrate, the same fine processing was performed on the film surface of the TFT substrate between the pixel region facing the rough surface layer of the CF substrate and the seal application position. In this way, a columnar rough surface layer with a side of 0.5 μm and a pitch of 1 μm was formed in a closed curve shape with a width of 4.2 mm on the TFT substrate side as well as the CF substrate.

  Next, in the seal application process, a hybrid type (UV + thermosetting) sealant was applied in a closed curve shape as a peripheral (auxiliary) seal and a main seal at predetermined positions so as to surround the pixel region. Next, in the liquid crystal dropping step, a liquid crystal material was dropped in a matrix at a predetermined position on the inner side of the main seal. Thereafter, in the bonding step, the two substrates were brought into contact with each other and pressed to uniformly diffuse the liquid crystal material throughout the pixel region between the substrates, thereby forming a uniform gap between the substrates.

  And in the case of conveyance to the next process, UV temporary hardening of some places was performed partially as temporary stop of a sealing material. Next, in the UV curing step, the sealing material was cured at a UV irradiation amount of 3000 mJ. At this time, it was confirmed by the rough surface layer that the uncured sealing material and the liquid crystal material were not in contact. Then, in the next thermosetting step, the sealing material was completely cured by heating at 120 ° C. for 1 hour. At this time, when the heating was started, it was confirmed that the semi-cured sealing material and the liquid crystal material were not in contact with each other due to the rough surface layer. Thereafter, when the thermosetting of the sealing material was completed, the liquid crystal material was diffused and filled in the entire area inside the seal, the sealing material and the liquid crystal material were in contact with each other, and a gap was also formed in the vicinity of the frame BM. After the thermosetting was completed, a gap measurement in the vicinity of the display part of the liquid crystal display panel and the frame BM was performed. As a result, it was confirmed that a uniform gap was obtained in the entire display area.

  A high-temperature and high-humidity test of the liquid crystal display device according to the embodiment of the present invention thus manufactured was performed. As a result of carrying out the 1500 h drive test at a temperature of 60 ° C. and a humidity of 60%, the occurrence of spots, unevenness, and peeling of the seal in the periphery of the seal of the liquid crystal display panel was not confirmed, and the display state was good. As a comparison, a liquid crystal display panel without a rough surface shape was produced, but it was confirmed that spots were generated in the periphery of the seal when the driving test reached 1000 h.

  Next, as a second example, another manufacturing method for the IPS mode liquid crystal display device according to the second embodiment of the present invention will be described.

  In the rough surface shape forming process of the CF substrate, an ashing process was performed on the surface of the frame BM between the pixel region and the seal application position using a plasma ashing apparatus. At this time, oxygen or a mixed gas of nitrogen and oxygen was used as a processing gas, and a scan type plasma ashing head was driven to irradiate plasma on a rough surface forming region. Thus, a hole-like rough surface layer having a diameter of 80 nm or less was formed in a closed curve shape around the pixel region. In addition, in a liquid crystal display panel with a gap distance between the frame BM-TFT substrate of 2.1 μm, in order to fabricate under a process condition in which the lead time from the bonding process out to the thermosetting process in is within 2 minutes, The width of the surface layer was 4.2 mm (the target value of the gap (gap) in the pixel area was 2.0 μm). On the other hand, in the rough surface shape forming process of the TFT substrate, the same ashing process was performed on the film surface of the TFT substrate between the pixel region facing the rough surface layer of the CF substrate and the seal application position. In this manner, a hole-like rough surface layer having a diameter of 80 nm or less was formed in a closed curve shape with a width of 4.2 mm on the TFT substrate side as well as the CF substrate.

  Next, in the seal application process, a hybrid type (UV + thermosetting) sealant was applied in a closed curve shape as a peripheral (auxiliary) seal and a main seal at predetermined positions so as to surround the pixel region. Next, in the liquid crystal dropping step, a liquid crystal material was dropped in a matrix at a predetermined position on the inner side of the main seal. Thereafter, in the bonding step, the two substrates were brought into contact with each other and pressed to uniformly diffuse the liquid crystal material throughout the pixel region between the substrates, thereby forming a uniform gap between the substrates.

  And in the case of conveyance to the next process, UV temporary hardening of some places was performed partially as temporary stop of a sealing material. In the next UV curing step, the sealing material was cured at a UV irradiation amount of 3000 mJ. At this time, it was confirmed by the rough surface layer that the uncured sealing material and the liquid crystal material were not in contact. Then, in the thermosetting step, the sealing material was completely cured by heating at 120 ° C. for 1 hour. At this time, when the heating was started, it was confirmed that the semi-cured sealing material and the liquid crystal material were not in contact with each other due to the rough surface layer. Thereafter, when the thermosetting of the sealing material was completed, the liquid crystal material was diffused and filled in the entire area inside the seal, the sealing material and the liquid crystal material were in contact with each other, and a gap was also formed in the vicinity of the frame BM. After the thermosetting was completed, a gap measurement in the vicinity of the display part of the liquid crystal display panel and the frame BM was performed. As a result, it was confirmed that a uniform gap was obtained in the entire display area.

  A high-temperature and high-humidity test of the liquid crystal display device according to the embodiment of the present invention thus manufactured was performed. As a result of carrying out the 1500 h drive test at a temperature of 60 ° C. and a humidity of 60%, the occurrence of spots, unevenness, and peeling of the seal in the periphery of the seal of the liquid crystal display panel was not confirmed, and the display state was good. As a comparison, a liquid crystal display panel without a rough surface shape was produced, but it was confirmed that spots were generated in the periphery of the seal when the driving test reached 1000 h.

  Next, as a third example, a method for manufacturing a TN mode liquid crystal display device according to a third embodiment of the present invention will be described.

  In the rough surface shape forming process of the CF substrate, the surface of the frame BM between the pixel region and the seal application position is finely processed by a focused ion beam (FIB) apparatus, each side is 0.5 μm, and the depth is 0.5 μm. Then, a columnar rough surface layer ([Ra] / [Sm] = 0.25) having a pitch of 1 μm was formed in a closed curve shape around the pixel region. Further, after the fluorine-based molecules were locally deposited on the columnar rough surface layer by a film forming apparatus, a fluorination treatment for polymerizing was performed to form a fluorine film having a thickness of about 100 nm. In addition, it is a liquid crystal display panel with a narrow frame structure with a gap distance between the frame BM-TFT substrate of 1.8 μm, and is manufactured under the process conditions that the lead time from the bonding process out to the thermosetting process in is within 2 minutes. For this purpose, the rough surface layer width was set to 2.8 mm (the target value of the gap (gap) in the pixel region was 1.7 μm). On the other hand, in the rough surface shape forming process of the TFT substrate, the rough surface shape and repellent property are similarly applied to the film surface of the TFT substrate between the seal application position from the pixel region facing the rough surface layer + fluorine film of the CF substrate. A liquid crystal film was applied. In this manner, a columnar rough surface layer having a side of 0.5 μm and a pitch of 1 μm and a fluorine film of 100 nm were formed in a closed curve shape with a width of 2.8 mm, similarly to the CF substrate.

  Next, in the seal application process, a hybrid type (UV + thermosetting) sealant was applied in a closed curve shape as a peripheral (auxiliary) seal and a main seal at predetermined positions so as to surround the pixel region. Next, in the Ag application step, Ag transfer was applied in a dot pattern at a predetermined position outside the seal. Next, in the liquid crystal dropping step, a liquid crystal material was dropped in a matrix at a predetermined position on the inner side of the main seal. Thereafter, in the bonding step, the two substrates were brought into contact with each other and pressed to uniformly diffuse the liquid crystal material throughout the pixel region between the substrates, thereby forming a uniform gap between the substrates.

  And in the case of conveyance to the next process, UV temporary hardening of some places was performed partially as temporary stop of a sealing material. In the next UV curing step, the sealing material was cured at a UV irradiation amount of 3000 mJ. At this time, it was confirmed by the rough surface layer that the uncured sealing material and the liquid crystal material were not in contact. Then, in the thermosetting step, the sealing material was completely cured by heating at 120 ° C. for 1 hour. At this time, when the heating was started, it was confirmed that the semi-cured sealing material and the liquid crystal material were not in contact with each other due to the rough surface layer. Thereafter, when the thermosetting of the sealing material was completed, the liquid crystal material was diffused and filled in the entire area inside the seal, the sealing material and the liquid crystal material were in contact with each other, and a gap was also formed in the vicinity of the frame BM. After the thermosetting was completed, a gap measurement in the vicinity of the display part of the liquid crystal display panel and the frame BM was performed. As a result, it was confirmed that a uniform gap was obtained in the entire display area.

  A high-temperature and high-humidity test of the liquid crystal display device according to the embodiment of the present invention thus manufactured was performed. As a result of carrying out the 1500 h drive test at a temperature of 60 ° C. and a humidity of 60%, the occurrence of spots, unevenness, and peeling of the seal in the periphery of the seal of the liquid crystal display panel was not confirmed, and the display state was good. For comparison, a liquid crystal display panel having no rough surface shape was produced, but it was confirmed that spots and partial seal peeling occurred in the periphery of the seal when the driving test reached 1000 h.

  INDUSTRIAL APPLICABILITY The present invention can be used for a liquid crystal display panel that sandwiches liquid crystal between a pair of opposing substrates, a manufacturing method thereof, and a liquid crystal display device that uses the liquid crystal display panel.

It is sectional drawing which shows the structure of the frame vicinity of the liquid crystal display panel which concerns on the 1st Embodiment of this invention. It is a top view of the liquid crystal display panel which shows the formation area of the rough surface shape of this invention. It is a top view of the liquid crystal display panel which shows the formation area of the rough surface shape of this invention. It is a flowchart which shows the manufacturing process of the liquid crystal display panel of this invention. It is sectional drawing which shows the structure of the frame vicinity of the liquid crystal display panel which concerns on the 2nd Embodiment of this invention. It is sectional drawing which shows the example of a shape of the rough surface structure of this invention. It is a figure which shows the correlation of the surface roughness and contact angle in a contact interface with a liquid crystal material. It is a schematic diagram of the TFT substrate in which a rough surface shape is formed between the pixel region of the present invention and the seal application position. It is sectional drawing which shows the structure of the frame vicinity of the liquid crystal display panel which concerns on the 3rd Embodiment of this invention. It is a conceptual diagram which shows the liquid crystal diffusion control effect by rough surface shape, (a) has shown the liquid crystal diffusion at the time of substrate bonding of this invention, (b) The liquid crystal diffusion at the time of the conventional substrate bonding. It is a figure which shows the correlation of the liquid-crystal diffusion speed in a frame BM formation part, and a gap. It is sectional drawing which shows the structure of the frame vicinity of the conventional liquid crystal display panel. It is a flowchart which shows the manufacturing process of the conventional liquid crystal display panel. It is sectional drawing which shows the other structure of the frame vicinity of the conventional liquid crystal display panel. It is sectional drawing which shows the other structure of the conventional liquid crystal display panel.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display panel 2 TFT substrate 3 CF substrate 4 Liquid crystal material 5 Seal material 6 Frame BM
7 Color Layer 8 Drive Circuit Layer 9 Alignment Film 10 Column Spacer 10a Spherical Spacer 11 Rough Surface Shape 11a Micro Rough Surface Structure 11b Micro Rough Surface Rough + Liquid-repellent Layer 12 Protrusion 13 Flow Control Wall

Claims (10)

In a liquid crystal display device in which a pair of opposing substrates are bonded with a closed-curved sealing material surrounding a pixel region, and a liquid crystal material is sandwiched between regions of the sealing material between the pair of substrates.
A frame region on the outer peripheral side of the pixel region and the inner peripheral side of the closed-curved sealing material,
The film surface in contact with the liquid crystal material in at least a part of the frame region of at least one substrate is a rough surface shape having a larger surface roughness than the film surface in contact with the liquid crystal material in the pixel region. Liquid crystal display device.   The liquid crystal display device according to claim 1, wherein the rough surface shape having a large surface roughness is formed in a closed curve shape so as to surround the pixel region.   3. The rough surface shape having a large surface roughness is formed on an organic film or an inorganic film facing the frame black matrix of one substrate and the frame black matrix of the other substrate. A liquid crystal display device according to 1.   4. The rough surface shape having a large surface roughness is a structure in which a large number of columnar or comb-shaped irregularities are disposed, or a structure in which a large number of holes are disposed. The liquid crystal display device according to 1.   5. The liquid crystal display device according to claim 1, wherein the film surface having a rough surface shape having a large surface roughness is made of a liquid repellent film.   The liquid crystal display device according to claim 5, wherein the liquid repellent film is a fluorine film or a silicone film. A seal coating step of applying a sealing material in a closed curve shape so as to surround a pixel region on one substrate; a liquid crystal dropping step of dropping a liquid crystal material in a region surrounded by the sealing material of the one substrate; In the method of manufacturing a liquid crystal display device, which includes at least a bonding step of bonding the substrate and the other substrate facing the one substrate, and a curing step of curing the sealing material in this order,
With respect to the one substrate before the liquid crystal dropping step and / or the other substrate before the bonding step, the outer peripheral side of the pixel region and the frame region on the inner peripheral side of the closed curved seal material At least a part of the film surface in contact with the liquid crystal material is subjected to ion beam treatment,
A method of manufacturing a liquid crystal display device, wherein the film surface is processed into a rough surface shape having a larger surface roughness than a film surface in contact with the liquid crystal material in the pixel region. A seal coating step of applying a sealing material in a closed curve shape so as to surround a pixel region on one substrate; a liquid crystal dropping step of dropping a liquid crystal material in a region surrounded by the sealing material of the one substrate; In the method of manufacturing a liquid crystal display device, which includes at least a bonding step of bonding the substrate and the other substrate facing the one substrate, and a curing step of curing the sealing material in this order,
With respect to the one substrate before the liquid crystal dropping step and / or the other substrate before the bonding step, the outer peripheral side of the pixel region and the frame region on the inner peripheral side of the closed curved seal material At least a part of the film surface in contact with the liquid crystal material is subjected to plasma ashing treatment,
A method of manufacturing a liquid crystal display device, wherein the film surface is processed into a rough surface shape having a larger surface roughness than a film surface in contact with the liquid crystal material in the pixel region.   9. The method of manufacturing a liquid crystal display device according to claim 7, wherein the ion beam treatment or the plasma ashing treatment for the one substrate is performed before the seal coating step.   10. The method of manufacturing a liquid crystal display device according to claim 7, further comprising forming a liquid repellent film after processing the film surface into a rough surface shape having a large surface roughness. .

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