JP2005107408A - Liquid crystal display element and manufacturing method of liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display element whose display defect caused by alignment unevenness generated in the vicinity of a border line of an outer peripheral end of an inorganic vapor deposition film can be suppressed or eliminated without depending on a technique incurring complication of a manufacturing process and to provide the manufacturing method of the liquid crystal display element. <P>SOLUTION: An inorganic alignment layer 3 is provided so as to cover the effective display region 2 of a substrate 1 such as a TFT substrate and a common electrode side substrate. The border line 5 of the outer peripheral end of the inorganic alignment layer 3 is positioned so as to overhang by ≥0.35 [mm] from the border line of an outer peripheral end of an effective display region to its outer side, and so as to retreat by ≥0.10 [mm] from the border line 8 of an inner peripheral end of a sealing material 7 to the inner side effective display region 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display element having an inorganic alignment film and suitably used, for example, as a light valve of a liquid crystal projector, and a method for manufacturing the liquid crystal display element.

  Conventionally, a TN type (Twisted Nematic type) liquid crystal display element (liquid crystal display panel) is used in a projection type liquid crystal display device called a so-called liquid crystal projector. In the TN type liquid crystal display element, an organic alignment film is used. Was used.

However, the amount of light incident on the light valve tends to become stronger due to the recent increase in brightness and cost reduction of liquid crystal projectors. There is concern about deterioration and deterioration of the film. Therefore, in recent years, it has been proposed to use an inorganic alignment film formed by vapor-depositing an inorganic material such as SiO ₂ particularly for a liquid crystal display element for a liquid crystal projector (Patent Document 1, Patent Document 2, (See Patent Document 3 and Patent Document 4.)

  However, since the inorganic alignment film tends to have a weak chemical interaction with the TN type liquid crystal, the alignment stability is low and has not yet reached a stage sufficient for practical use.

On the other hand, when a film formed by oblique deposition of SiO ₂ is used as an inorganic alignment film, it is known that the film is vertically aligned if it is a vertical alignment type (see Patent Documents 5 and 6). However, this also has a weak alignment regulating force for liquid crystal molecules compared to the alignment regulating force for liquid crystal molecules due to molecular interaction between the alignment polymer and the liquid crystal molecules in an organic vertical alignment film such as polyimide.

  For this reason, when an alignment layer is formed by oblique deposition of an inorganic material, immediately after the liquid crystal is injected into the liquid crystal cell, an effective alignment state in which the liquid crystal molecules in the liquid crystal layer can sufficiently withstand practical use. Although it can be controlled to (initial alignment state), the alignment state of liquid crystal molecules is disturbed from the vicinity of the sealing material over time due to the influence of the sealing material made of, for example, an ultraviolet curable resin adhesive. Initially, the initial alignment state of the liquid crystal molecules cannot be maintained over time, and the display quality may deteriorate from the periphery of the display screen.

As a technique for avoiding such deterioration in display quality, a structure in which an organic vertical alignment film having a strong alignment regulating force is provided in the vicinity of a seal material that is not exposed to light, and an inorganic vertical alignment film is provided in an effective display area There has been proposed a liquid crystal display device or the like (see Patent Document 7).
JP 59-188621 A JP-A-63-172121 JP 54-46576 A JP-A-53-84750 JP-A-5-203958 JP-A-7-159788 JP 2002-214616 A

  However, in the method as described above, it is necessary to pattern the organic vertical alignment film by using printing or photolithography after forming the inorganic alignment film by oblique vapor deposition. There is an inconvenience that the forming process becomes complicated. In addition, there is a risk that the surface of the obliquely deposited film that is extremely sensitive to the surface state is contaminated, leading to poor liquid crystal alignment state in the vicinity thereof.

  Further, the surface of the inorganic vapor deposition film tends to be non-uniform at the outer peripheral edge boundary line of the inorganic vapor deposition film (in other words, the boundary between the vapor deposited portion and the non-vapor deposited portion). For this reason, an inorganic vapor deposition film formed by obliquely depositing an inorganic material generally has a weaker orientation regulating force near the outer peripheral edge boundary line, and as a result, near the outer peripheral edge boundary line of the inorganic vapor deposition film. The present inventors have confirmed through various experiments and analyzes that the probability of occurrence of uneven orientation is high. When alignment unevenness occurs in the vicinity of the boundary line of the outer peripheral edge of such an inorganic vapor deposition film, an unsightly display defect may occur in the peripheral portion of the display screen.

  The present invention has been made in view of such problems, and the object thereof has occurred in the vicinity of the boundary line of the outer peripheral edge of the inorganic vapor-deposited film, without relying on the above-described technique that complicates the manufacturing process. An object of the present invention is to provide a liquid crystal display element and a method of manufacturing the liquid crystal display element that can suppress or eliminate the occurrence of display defects due to alignment unevenness.

  In the liquid crystal display element according to the present invention, a liquid crystal layer is sandwiched between a pair of substrates that are arranged to face each other and whose periphery is sealed with a sealing material, and the surface of at least one of the pair of substrates An inorganic alignment film is formed on at least the effective display area of the inorganic alignment film, and the outer peripheral edge boundary line extends from the outer peripheral edge boundary line of the effective display area to the outside thereof by 0.35 [mm] or more, and The seal material is provided so as to be within a position of 0.10 [mm] on the effective display region side from the inner peripheral end boundary line of the seal material.

  The method of manufacturing a liquid crystal display device according to the present invention includes forming an inorganic alignment film by oblique deposition on at least the effective display region of the surface of at least one of the pair of substrates, and causing the pair of substrates to face each other. In order to manufacture a liquid crystal display element by placing a liquid crystal layer between the pair of substrates and sealing the periphery with a sealing material, the peripheral edge boundary line of the inorganic alignment film is an effective display area. Extending from the outer peripheral edge boundary line to the outside by 0.35 [mm] or more, and from the inner peripheral edge boundary line of the sealing material to the effective display area side within a position of 0.10 [mm]. is there.

  In the liquid crystal display element or the method of manufacturing a liquid crystal display element according to the present invention, the inorganic alignment film has an outer peripheral edge boundary line extending from the outer peripheral edge boundary line of the effective display region to the outside by 0.35 [mm] or more, and a seal Since it is formed to be within a position of 0.10 [mm] from the inner peripheral edge boundary line of the material to the effective display region side, the manufacturing process is complicated, such as a method of coexisting an organic alignment film and an inorganic alignment film Even if it does not depend on the technique which invites, the display defect resulting from the orientation nonuniformity which has arisen in the vicinity of the outer peripheral end boundary line of the inorganic vapor deposition film does not reach the effective display area.

  Note that the inorganic alignment film can be formed to have a film thickness within a range from 50 [nm] to 250 [nm]. The inorganic alignment film may be formed by obliquely depositing silicon oxide at an angle in the range of 40 to 70 degrees with the substrate surface set to 0 degrees in the horizontal direction. However, it is needless to say that the above numerical range is a desirable mode and is not limited to this.

  In addition, as described above, the outer peripheral edge boundary line of the inorganic alignment film is located at a position extending 0.35 [mm] or more from the outer peripheral edge boundary line of the effective display region to the outside thereof, and the inner peripheral edge of the sealing material In order to achieve a position that is retracted by 0.10 [mm] or more from the boundary line to the inner effective display area, the space between the outer peripheral edge boundary line of the effective display area and the inner peripheral edge boundary line of the sealing material Therefore, it is necessary to set the distance to at least 0.45 [mm] or more. That is, the width of the so-called screen peripheral edge between the boundary line of the effective display area and the sealing material needs to be set to at least 0.45 [mm] or more.

  According to the liquid crystal display element and the manufacturing method of the liquid crystal display element of the present invention, the inorganic alignment film is placed at a position where the outer peripheral edge boundary line extends beyond the outer peripheral edge boundary line of the effective display region by 0.35 [mm] or more. Because it was formed so as to come, it was generated near the boundary line of the outer peripheral edge of the inorganic vapor deposition film, without depending on the method of complicating the manufacturing process such as the method of coexisting the organic alignment film and the inorganic alignment film Display defects caused by uneven orientation do not reach the effective display area. Therefore, it is possible to suppress or eliminate the occurrence of display defects due to the alignment unevenness that has occurred in the vicinity of the outer peripheral edge boundary line of the inorganic vapor-deposited film without complicating the manufacturing process.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 specifically shows a portion from the outer peripheral edge boundary line of the effective display area to the position where the outer sealing material is disposed in the liquid crystal display element according to the embodiment of the present invention. In order to avoid complication of illustration, each pixel provided in, for example, an effective display area other than the vicinity of the outer peripheral edge boundary line of the inorganic alignment film which is the most characteristic part in the liquid crystal display element of the present embodiment. Detailed descriptions and illustrations of the same parts as those of a general liquid crystal display element, such as a pixel electrode for constituting the display, are omitted.

In this liquid crystal display device, on the effective display region 2 of the surface of the substrate 1, an inorganic alignment layer 3 is at an angle in the range of 40 to 70 degrees of the surface of the substrate 1 as a horizontal direction 0 °, SiO ₂ (silicon dioxide ) By oblique vapor deposition. The thickness of the inorganic alignment film 3 is, for example, designed to allow an error of ± 50 [nm] with a center value of 100 [nm], and within a range from 50 [nm] to 250 [nm]. Is formed.

  The inorganic alignment film 3 has an outer peripheral edge boundary line 5 at a distance of 0.35 [mm] or more, for example, 0.50 [mm], from the outer peripheral edge boundary line 6 of the effective display region 2 to the outside thereof. A position that is extended over a distance (given a margin), and a position that is receded by 0.10 [mm] or more from the inner peripheral end boundary 8 of the sealing material 7 to the inner effective display area 2 Is provided. Therefore, the space at the peripheral edge of the screen between the outer peripheral end boundary line of the effective display area 2 and the inner peripheral end boundary line 8 of the sealing material 7 is at least 0.45 [mm], for example, 0.50 [mm]. ] The above size (width) is set.

  A pair of substrates 1 are arranged so as to face each other, and the periphery of the substrate 1 is sealed with a sealing material 7 and adhered, and the two substrates are formed. A liquid crystal layer (not shown) is sandwiched between one gap, and the main part of the liquid crystal display element is configured.

  In this way, the inorganic alignment film 3 is formed such that the outer peripheral edge boundary line 5 comes to a position extending from the outer peripheral edge boundary line 6 of the effective display region 2 to the outside by 0.35 [mm] or more. Even if it does not depend on a method that causes complication of the manufacturing process such as a method of coexisting an organic alignment film and an inorganic alignment film (not shown), it occurred in the vicinity of the outer peripheral edge boundary 5 of the inorganic alignment film 3. It is possible to avoid the display defect due to the alignment unevenness reaching the effective display area 2. As a result, it is possible to suppress or eliminate the occurrence of display defects caused by the alignment unevenness that has conventionally occurred in the vicinity of the outer peripheral edge boundary line 5 of the inorganic alignment film 3.

  In addition, the inorganic alignment film 3 is provided such that the outer peripheral edge boundary line 5 thereof recedes from the inner peripheral edge boundary line 8 of the sealing material 7 to the effective display region 2 further inside by 0.10 [mm] or more. Therefore, a distance of 0.10 [mm] or more is provided between the inorganic alignment film 3 and the sealing material 7, and as a result, chemical interference between the inorganic alignment film 3 and the sealing material 7 or the like. As a result, it is possible to suppress or eliminate the deterioration of the liquid crystal layer at that portion and the occurrence of display defects due to the deterioration.

  Next, examples of the liquid crystal display element and the manufacturing method thereof according to the present embodiment will be described.

  First, when performing oblique vapor deposition of the inorganic alignment film 3, the sealing material 7 is used to avoid contamination from the sealing material 7 and so that the inorganic alignment film 3 is not deposited near the application portion of the sealing material 7. A metal mask 9 having a size of 0.10 [mm] projecting from the coated portion toward the effective display area 2 was used. In order to prevent damage or contamination to the surface of the substrate 1 to be deposited, oblique deposition is performed with the metal mask 9 slightly lifted by a height Δd in the normal direction from the surface of the substrate 1. It was.

  However, at this time, the outer peripheral edge boundary line 5 of the inorganic alignment film 3 is projected from the outer peripheral edge boundary line 6 of the effective display region 2 to the outside thereof over a distance of 0.35 [mm] (stretched). For the purpose of comparison, the metal mask 9 is used to carry out the vapor deposition process as shown in FIG. A substrate as shown in FIG. 5 is manufactured with a size (distance) as small as 0.10 [mm] less than 0.35 [mm], and a liquid crystal display device using the substrate is manufactured. did. Further, a plurality of substrates 1 in which the overhanging of the inorganic alignment film 3 is set to a plurality of types of distances less than 0.35 [mm] are manufactured, and further, liquid crystal display elements are respectively manufactured using them. The presence or absence of display defects was confirmed.

More specifically, in this oblique deposition process, the deposition tank is kept in a vacuum state as much as possible so that molecules other than SiO ₂ are purged as much as possible. set up of the SiO ₂ solid is, by evaporating it, the surface of the substrate mounted on the tank in the upper 1 (i.e. TFT side substrate or the counter substrate), 40 ° to 70 ° in the horizontal direction as 0 ° The inorganic alignment film 3 was formed so as to have a film thickness of 50 to 250 [nm] while being tilted within the range.

  The substrate 1 formed with the inorganic alignment film 3 was incorporated to complete a liquid crystal display element, which was driven to display an image, and the display quality (the presence or absence of display defects, etc.) was confirmed.

  As a result, no alignment unevenness or display defect due to the sealing material 7 occurred. However, regardless of the deposition angle and film thickness, the plan view of FIG. As shown, the display unevenness 21 due to the alignment disorder occurred in the portion of the effective display area 2 near the outer peripheral edge boundary line 6.

  Therefore, this time, a plurality of examples of substrates 1 are manufactured by setting the distance of the extension (stretching) of the outer peripheral end boundary line 5 of the inorganic alignment film 3 to 0.35 [mm] or more, and liquid crystal display elements each incorporating them are prepared. They were produced and checked for the presence or absence of display defects.

  At this time, on the substrate 1 of the liquid crystal display element, the method of forming the inorganic alignment film 3 by performing oblique vapor deposition in a state where the portion to which the sealing material 7 is applied is masked (covered) with the metal mask 9. Same as above, but masking causes an unstable shadow in the vicinity of the outer peripheral end portion of the deposited film, or due to chemical interference of the sealing material 7, etc. There is also a possibility that unevenness of the film is generated in the inorganic alignment film 3 and the display quality is deteriorated. Therefore, in order to prevent such uneven deposition, etc., as shown in FIG. 4, a taper having an inclination angle α is partially provided on the effective display region 2 side of the metal mask 9.

  That is, the distance Le between the outer peripheral edge boundary line 6 of the effective display area 2 on the side close to the vapor deposition source and the outer peripheral edge boundary line 5 of the deposition target area (in other words, the inorganic alignment film 3) is within the sealing material 7. The distance from the peripheral boundary 8 to the peripheral boundary 6 of the effective display area 2 is La, the height of the metal mask 9 in the normal direction from the surface of the substrate 1 is Δd, the thickness is ΔT, and the metal mask 9 is represented by the following equation: Le = La − {(Δd + ΔT) / Tanφ + Lo} where Lo is the overhang distance 9 and the horizontal tilt of the substrate 1 (in other words, the deposition angle) is φ. it can. Based on this equation, the outer peripheral boundary of the effective display area 2 is reduced by reducing the effective ΔT of the metal mask 9 by, for example, tapering a portion of the metal mask 9 near the effective display area 2 with an inclination angle α. The distance Le from the line 6 to the outer peripheral end boundary line 5 of the inorganic alignment film 3 can be further increased.

  Therefore, by providing such a taper of the inclination angle α, the outer peripheral edge boundary line 5 of the inorganic alignment film 3 is extended from the outer peripheral edge boundary line 6 of the effective display region 2 to the outside thereof by Le = 0.35 [mm] or more. The metal mask 9 that can be provided over a distance is floated in the normal direction of the substrate 1 by a height Δd, and other conditions are oblique deposition as described above, A substrate 1 is produced in which an inorganic alignment film 3 is provided so that its outer peripheral edge boundary line 5 protrudes from the outer peripheral edge boundary line 6 of the effective display region 2 to the outside thereof over a distance of 0.35 [mm] or more. did. Then, a liquid crystal display element incorporating the substrate 1 was completed, and it was driven to check whether or not display defects occurred. As a result, the occurrence of display unevenness was not visually recognized at all.

  Summarizing the results of the above experiment, the distance between the outer peripheral edge boundary line 6 of the effective display region 2 and the outer peripheral edge boundary line 5 of the inorganic alignment film 3 and the visual inspection of an inspector who is extremely skilled in the inspection of liquid crystal display elements. As shown in FIG. 6, the relationship with the level of display unevenness confirmed by the display is substantially visually insignificant if the distance is longer than 0.35 [mm]. The display quality level is evaluated as a non-defective product that is not visually recognized. For example, when it is less than 0.35 [mm], such as 0.10 [mm], display unevenness that impairs the display quality level occurs. It became clear that.

  Here, the film thickness of the inorganic alignment film 3 is in the order of 100 [nm] (50 to 150 [nm]) (digit or numerical scale) as described above. 6 is not less than 0.35 [mm], and the order is 3500 times the film thickness of the inorganic alignment film 3. Assuming from the order of the thickness of the liquid crystal molecules contained in the liquid crystal layer and the inorganic alignment film 3 (about 100 [nm]), the outer peripheral edge boundary line 6 of the effective display region 2 and the outer peripheral edge boundary line of the inorganic alignment film 3 Although the order of the desired distance between the two is also assumed to be about [nm] or [μm], in practice, as described in the above embodiment, liquid crystal molecules (not shown) and It has been found that the order of [mm] (or 100 [μm]), which cannot be expected from the order of the thickness of the inorganic alignment film 3, must be obtained.

  The distance (0.35 [mm] or more) between the outer peripheral edge boundary line 5 of the inorganic alignment film 3 and the outer peripheral edge boundary line 6 of the effective display region 2 is the size of the diagonal dimension of the entire display screen. There is little need to change in response to. That is, the liquid crystal display element having a display screen of any size may be set to 0.35 [mm] or more as described above.

  In general, even if a liquid crystal display element has a screen of any size, as shown schematically in FIG. 2, a display such as a display unevenness 21 caused by an alignment defect is provided at the periphery of the display screen. If a defect has occurred, the presence of the display unevenness 21 will be noticeably conspicuous, and the display defect will be the main factor that significantly reduces the display quality. Therefore, in order to improve the display quality, an alignment defect near the outer peripheral edge boundary 5 of the inorganic alignment film 3 causes the display quality of the effective display region 2 particularly in the peripheral portion regardless of the size of the display screen. This is because it is necessary to prevent adverse effects on the environment. For that purpose, the method as described in the present embodiment or the present example is effective.

  In addition, the liquid crystal display element of the said embodiment can be utilized suitably for the transmissive | pervious liquid crystal display panel etc. which are used, for example as a light valve of a liquid crystal projector.

  In addition to using the metal mask 9 as described above, after depositing an inorganic film on the entire surface of the substrate 1, the portion of the inorganic film to be coated with the sealing material 7 is removed by, for example, an etching method, It is also possible to form an inorganic alignment film 3 having a predetermined planar shape.

  The present invention can be used as a liquid crystal display element having an inorganic alignment film suitable for, for example, a transmissive liquid crystal display panel used as a light valve of a liquid crystal projector and a method for manufacturing the same.

It is the figure which extracted especially the part from the outer peripheral edge boundary line of the effective display area on a board | substrate to the position where the sealing material of the outer side is arrange | positioned in the liquid crystal display element which concerns on one embodiment of this invention. It is the figure which represented typically the state which the display nonuniformity resulting from orientation disorder generate | occur | produced in the part near the outer periphery end boundary line of an effective display area. An example of a vapor deposition process in the case where the outer peripheral edge boundary line of the inorganic alignment film is allowed to protrude from the outer peripheral edge boundary line of the effective display region to the outside thereof only over a distance of less than 0.35 [mm] is shown. FIG. An example of a vapor deposition process in the case where an overhang of an inorganic alignment film over a distance of 0.35 [mm] or more is provided by partially tapering an inclination angle α on the effective display region side of the metal mask. FIG. It is the figure showing an example of the board | substrate which made the outer peripheral edge boundary line of an inorganic alignment film protrude only from the outer peripheral edge boundary line of an effective display area to the outer side over the distance of less than 0.35 [mm]. is there. Correspondence between the distance between the outer peripheral edge boundary line of the effective display area and the outer peripheral edge boundary line of the inorganic alignment film and the level of display unevenness confirmed by the visual inspection of an inspector who is extremely skilled in the inspection of liquid crystal display elements It is the figure which put together and represented the graph.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Effective display area, 3 ... Inorganic alignment film, 5 ... Outer peripheral edge boundary line of inorganic alignment film, 6 ... Outer peripheral edge boundary line of effective display area, 7 ... Seal material, 8 ... Inner circumference of seal material Edge border, 9 ... metal mask

Claims (8)

A liquid crystal layer is sandwiched between a pair of substrates that are arranged to face each other and are sealed with a sealing material, and are inorganic on at least an effective display area on the surface of at least one of the pair of substrates. A liquid crystal display element formed by forming an alignment film,
The inorganic alignment film has an outer peripheral end boundary line extending from the outer peripheral end boundary line of the effective display region to the outside by 0.35 [mm] or more, and from the inner peripheral end boundary line of the sealing material to the effective display region side. It is provided so that it may be within the position of 0.10 [mm]. The liquid crystal display element characterized by the above-mentioned. The liquid crystal display element according to claim 1, wherein the inorganic alignment film is formed to have a film thickness within a range of 50 [nm] to 250 [nm]. 2. The inorganic alignment film is formed by obliquely depositing silicon oxide at an angle in a range of 40 to 70 degrees with the surface of the substrate being set to 0 degrees in the horizontal direction. Liquid crystal display element. The distance between the outer peripheral edge boundary line of the effective display area and the inner peripheral edge boundary line of the seal material is set to a distance of 0.45 [mm] or more, and the outermost shape, the thickness of the seal material, and the size of the effective display area The liquid crystal display element according to claim 1, wherein the liquid crystal display element is restricted. An inorganic alignment film is formed by oblique vapor deposition on at least the effective display area of the surface of at least one of the pair of substrates, the pair of substrates are disposed to face each other, and a liquid crystal is disposed in a gap between the pair of substrates. In manufacturing a liquid crystal display element by sandwiching the layers and sealing the periphery with a sealing material,
The outer peripheral end boundary line of the inorganic alignment film extends 0.35 [mm] or more from the outer peripheral end boundary line of the effective display region to the outside thereof, and the effective display region side from the inner peripheral end boundary line of the seal material is 0.10 [ mm]]. A manufacturing method of a liquid crystal display element, The method for manufacturing a liquid crystal display element according to claim 5, wherein the inorganic alignment film is formed to have a film thickness within a range of 50 [nm] to 250 [nm]. 6. The liquid crystal display element according to claim 5, wherein the inorganic alignment film is formed by obliquely depositing silicon oxide at an angle in a range of 40 to 70 degrees with the surface of the substrate being set at 0 degrees in the horizontal direction. Manufacturing method. The distance between the outer peripheral edge boundary line of the effective display area and the inner peripheral edge boundary line of the seal material is set to a distance of 0.45 [mm] or more, from the outermost shape, the seal material thickness, and the size of the effective display area. The liquid crystal display element manufacturing method according to claim 5, wherein the liquid crystal display element is set within a restricted position.

Images