JP4144545B2 - Liquid crystal device manufacturing method, liquid crystal device, and electronic apparatus - Google Patents

Description

  The present invention relates to an alignment control technique for a liquid crystal device.

In general, in a liquid crystal device used as a light valve of a liquid crystal projector or a display such as a mobile phone, an alignment film for controlling the alignment of liquid crystal molecules is formed on the outermost surface of a substrate sandwiching the liquid crystal layer. As this alignment film, a film obtained by rubbing an organic film such as polyimide is widely used. However, such an organic alignment film is excellent in the alignment force, but is weak against heat and light, and has a problem that the alignment force gradually decreases with long-term use. For example, when mounted on a projector that is irradiated with high-intensity light with a light flux density of about ² to 10 (lm / mm ² ), the alignment film is gradually decomposed by light and heat from the light source, and the liquid crystal molecules are In some cases, it may become impossible to arrange at a desired pretilt angle.
On the other hand, a technique has been proposed in which an inorganic alignment film is used as the alignment film and liquid crystals are aligned by the shape effect of the inorganic alignment film. For example, Patent Document 1 discloses a method of forming columnar structures arranged obliquely with respect to a substrate by oblique vapor deposition. Such an inorganic alignment film is superior in light resistance and solvent resistance compared to an organic alignment film such as polyimide, and can improve the reliability of the liquid crystal device.
JP-A-57-112714

However, since such a conventional inorganic alignment film uses a vacuum process in the film forming process, the manufacturing apparatus becomes large. Further, when forming an alignment film on the electrode surface of an active matrix type liquid crystal device, a stepped portion is formed on the electrode surface corresponding to the position where the switching element is formed, and a portion shadowed from the oblique deposition direction in the stepped portion. May be possible. Such a defect leads to a decrease in reliability as the alignment film, and causes a display defect when, for example, a liquid crystal device is used as a display device.
The present invention has been made in view of such circumstances, and an object thereof is to provide a method for manufacturing a liquid crystal device capable of easily forming an alignment film having high alignment ability and excellent alignment stability and reliability. And

  In order to solve the above-described problems, a method for manufacturing a liquid crystal device according to the present invention is a method for manufacturing a liquid crystal device in which a liquid crystal is sandwiched between a pair of opposing substrates, and at least one of the pair of substrates. A step of forming an inorganic alignment film on a surface, wherein the forming step of the inorganic alignment film includes a step of forming a metal film on the surface of the one substrate, and anodizing the metal film using an electrolytic solution. A step of forming an anodized film having a plurality of fine holes on the surface of the one substrate, and a fibrous metal plated film for orienting the liquid crystal in the fine holes of the anodized film by electrolytic plating Forming the step.

Generally, when a metal film is anodized, various films can be formed from a dense and defect-free film to a porous film by changing the anodizing conditions. For example, when anodization is performed for a short time with a large current, a porous film having a large number of micropores randomly formed is formed. A film without defects is formed. In addition, when the intermediate condition is adopted, a porous film having a two-dimensional array structure in which a large number of micropores are regularly arranged is formed. In this method, a metal plating film is formed inside the fine holes formed by using the anodic oxidation method, and a number of fine conductive protrusions (columnar structures) are formed on the substrate surface by the fibrous metal plating film obtained thereby. ). Such protrusions are two-dimensionally arranged at a constant density on the surface of the substrate, so that they have an alignment force in the direction along the protrusions.
According to this method, since the liquid crystal is reliably aligned along these protrusions, a high alignment ability can be realized. In addition, since this alignment film is made of an inorganic material, it is superior in light resistance and solvent resistance compared to an organic alignment film such as polyimide, and liquid crystal alignment is realized with a fine columnar structure (that is, Therefore, stable orientation can be obtained. Furthermore, since there is no shadowed portion as in oblique deposition, no alignment unevenness occurs. In addition, when the anodizing method is used, the pitch, size, shape, depth, etc. of the micropores can be adjusted according to the anodizing conditions, so that a stable alignment state can be easily realized by optimization. It is possible.

  In the method for manufacturing a liquid crystal device according to the present invention, the plurality of fine holes may be two-dimensionally arranged (that is, the fibrous conductive protrusions are two-dimensionally arranged). By doing so, the liquid crystal can be aligned in approximately one direction. Specifically, the plurality of micro holes are formed substantially perpendicular to the one substrate (that is, the fibrous conductive protrusions are two-dimensionally arranged substantially perpendicular to the one substrate. ). In this case, the liquid crystal exhibits a vertical alignment in the initial state (voltage non-application state).

  In the method for manufacturing a liquid crystal device of the present invention, the step of forming the anodic oxide film may be performed in a magnetic field. In this case, it is possible to control the extending direction of the fine holes by controlling the magnetic field. In other words, anodic oxidation attracts oxygen ions in the electrolyte solution to the surface of the metal film by electrical action and oxidizes the metal surface. Therefore, when anodic oxidation is performed in a magnetic field, Anisotropy occurs in the movement, and the growth direction of the oxide film becomes directional. Since the anisotropy in the growth direction of the oxide film changes depending on the strength of the magnetic field, the tilt amount of the micropores (that is, the tilt angle of the liquid crystal) can be controlled by adjusting the strength of the magnetic field. Is possible.

  In this method, in the step of forming the anodic oxide film, the magnetic field is applied parallel or obliquely to the one substrate, and the plurality of fine holes are arranged in an inclined state with respect to the one substrate. (That is, the fibrous conductive protrusions are arranged in an inclined state with respect to the one substrate). When the micropores are tilted in this way, the liquid crystal shows an alignment state that is uniformly tilted with respect to the substrate surface in the initial state. The tilt angle of the liquid crystal can be controlled according to the tilt, and alignment defects such as a reverse domain can be eliminated. Further, by arranging such fine holes two-dimensionally, the liquid crystal can be aligned in almost one direction. In this method, it is desirable that the magnetic field strength in the step of forming the anodic oxide film is 1T or more. By doing so, a sufficient tilt can be obtained.

  In the liquid crystal device manufacturing method of the present invention, the metal film may be made of aluminum (Al). As the metal film, a so-called valve metal such as tungsten (Ta), titanium (Ti), magnesium (Mg), or an alloy thereof can be used, and among them, aluminum is as described above. Easy to form micropores. In the method for producing a liquid crystal device according to the present invention, it is possible to suitably use the electrolytic solution made of a weakly acidic electrolytic solution such as oxalic acid, phosphoric acid, sulfuric acid, or chromic acid.

  In the method for manufacturing a liquid crystal device according to the present invention, in the step of forming the anodic oxide film, only the surface of the metal film is anodized, and the other metal film is left as an electrode for applying a voltage to the liquid crystal. It can be a process. By doing so, it is not necessary to separately form an electrode for liquid crystal alignment, and the process becomes simple.

  In the method for manufacturing a liquid crystal device of the present invention, an electrode for applying a voltage to the liquid crystal is provided on the surface of the one substrate, and the step of forming the inorganic alignment film is performed between the electrode and the metal film. The method may include a step of forming a protective film for protecting the surface of the electrode. Thus, by performing anodization after forming a protective film, it is possible to prevent the underlying electrode film from being corroded by the electrolytic solution. Further, when an insulating protective film is provided between the electrode and the metal film, for example, even if a part of the metal film is left unoxidized in the step of forming the anodic oxide film, the electrode is thereby removed. There is no short circuit between them.

In the method for manufacturing a liquid crystal device of the present invention, the step of forming the inorganic alignment film may include a step of removing the anodic oxide film after the formation of the metal plating film. In this case, the inorganic alignment film is constituted only by the conductive protrusions. Therefore, unlike conventional alignment films made of an insulating material (such as organic alignment films such as polyimide and inorganic insulating alignment films such as SiO ₂ oblique deposition film), this inorganic alignment film is applied when a voltage is applied to the liquid crystal. Does not cause a problem of voltage drop due to functioning as a dielectric. That is, the voltage applied to the electrodes can be fully applied to the liquid crystal.

  Moreover, in the manufacturing method of the liquid crystal device of this invention, the process of forming the said inorganic alignment film on the surface of the other board | substrate of a pair of said board | substrate can be provided. Thus, the reliability of a liquid crystal device can be improved more by making the alignment film of both the substrates into an inorganic alignment film.

  In the method for manufacturing a liquid crystal device of the present invention, a step of forming an organic alignment film on the surface of the other substrate of the pair of substrates can be provided. Thus, by making the alignment film of the other substrate an organic alignment film having excellent alignment ability, the initial alignment state after filling the liquid crystal (for example, the alignment state immediately after liquid crystal injection) can be stabilized. That is, in a shape alignment film that aligns liquid crystal by shape effect, the liquid crystal tends to be in a metastable alignment state, and the alignment state immediately after filling the liquid crystal tends to be unstable. For this reason, in order to make the liquid crystal transition to the most stable alignment state, in addition to the alignment force due to the shape effect described above, it is desirable to apply some alignment force that assists this. On the other hand, in the case of an organic alignment film such as polyimide, the alignment of the liquid crystal is strongly regulated by the intermolecular force between the organic alignment film and the liquid crystal, so that the transition to the stable alignment is performed more reliably than the shape alignment film described above. The time until transition is short. For this reason, by using the organic alignment film on the opposite substrate side as in this method, the alignment regulating force of the organic alignment film can be indirectly transmitted to the one substrate side via the liquid crystal layer. Thus, the alignment state of the liquid crystal in the vicinity of the inorganic alignment film can be reliably changed to the most stable state in a short time.

The liquid crystal device of the present invention is a liquid crystal device in which liquid crystal is sandwiched between a pair of opposing substrates, and a plurality of fine fibers for aligning the liquid crystal on the surface of at least one of the pair of substrates. And an inorganic alignment film made of conductive conductive protrusions.
According to this configuration, since the liquid crystal is reliably aligned along these conductive protrusions, a high alignment ability can be realized. In addition, since this alignment film is made of an inorganic material, it is more reliable than an organic alignment film such as polyimide, and since the alignment is realized by the shape effect, a stable alignment can be obtained. Further, in this configuration, unlike a conventional alignment film made of an insulating material, a voltage drop does not occur due to the presence of the inorganic alignment film when a voltage is applied, and the voltage can be fully applied to the liquid crystal.

In the liquid crystal device of the present invention, the plurality of conductive protrusions may be two-dimensionally arranged. By doing so, the liquid crystal can be aligned in approximately one direction. Specifically, the plurality of conductive protrusions may be formed substantially perpendicular to the one substrate. In this case, the liquid crystal exhibits a vertical alignment in the initial state (voltage non-application state). Alternatively, the plurality of conductive protrusions may be formed to be inclined with respect to the one substrate. In this case, the liquid crystal exhibits tilt alignment in the initial state. In these cases, a vertical alignment type liquid crystal device can be realized by making the liquid crystal a nematic liquid crystal having a negative dielectric anisotropy.
In the liquid crystal device of the present invention, it is desirable that the plurality of conductive protrusions are regularly arranged at a constant pitch. In addition, it is desirable that the plurality of conductive protrusions have substantially the same size, shape, and height. By doing so, uniform orientation can be obtained.

In the liquid crystal device of the present invention, the inorganic alignment film may be provided on the surfaces of both the pair of substrates. Thus, the reliability of a liquid crystal device can be improved more by making the alignment film of both the substrates into an inorganic alignment film.
In the liquid crystal device of the present invention, an organic alignment film may be provided on the surface of the other substrate of the pair of substrates. Thus, the initial alignment state after liquid crystal filling can be stabilized by making the alignment film of the other substrate an organic alignment film having excellent alignment ability.

  An electronic apparatus according to the present invention includes a liquid crystal device manufactured using the above-described method. Thereby, an electronic apparatus with high display quality and excellent reliability can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing referred to below, the size and thickness of each part are appropriately changed in order to make the drawing easy to see.

[First Embodiment]
[Liquid Crystal Device]
FIG. 1 is a schematic cross-sectional view showing a schematic configuration of the liquid crystal device of the present embodiment. The liquid crystal device 1 shown in FIG. 1 has a configuration in which a liquid crystal layer 30 is sandwiched between a pair of opposing substrates 10 and 20. A lower electrode 11 and an alignment film 12 are sequentially formed on the inner surface side (liquid crystal layer side) of the lower substrate 10, and an upper electrode 21 and an alignment film 22 are sequentially formed on the inner surface side of the upper substrate 20. . The liquid crystal device 1 may have an active matrix type or passive type structure. When adopting an active matrix structure, either a TFT (Thin Film Transistor) or a TFD (Thin Film Diode) having an MIM structure can be used as the pixel switching element. Further, the liquid crystal device 1 may have either a transmission type or a reflection type structure, and a color filter may be provided on these substrates as necessary.

  In the present embodiment, the alignment films 12 and 13 are configured as inorganic alignment films having a large number of protrusions on the surface. Specifically, the alignment films 12 and 13 include a porous alumina anodic oxide film 12a and a large number of fine fibrous metal plating films 12b formed in the pores of the anodic oxide film. (See FIG. 4) These metal plating films 12b are formed so as to protrude from the surface of the anodic oxide film 12a, thereby forming the above-mentioned many protrusions. The alignment films 12 and 13 are a kind of shape alignment film that performs alignment control by shape effect (interaction between the structure formed on the film surface and the object). In this example, the alignment films 12 and 13 are formed on the surface of the oxide film. The projected structure defines the alignment state of the liquid crystal L in the vicinity of the alignment film.

  Generally, when a metal film is anodized, various films can be formed from a dense and defect-free film to a porous film by changing the anodizing conditions. For example, when anodization is performed for a short time with a large current, a porous film having a large number of micropores randomly formed is formed. A film without defects is formed. In addition, when the intermediate condition is adopted, a porous film having a two-dimensional array structure in which a large number of micropores are regularly arranged is formed. Such micropores can be formed with a diameter of several nm to several hundred nm depending on the conditions of anodization. When such an anodic oxide film having fine holes is used as the alignment film, the liquid crystal L is adsorbed in the fine holes to align the liquid crystal L in the direction along the inner wall of the holes or in the direction perpendicular thereto. Can do. In this embodiment, appropriate anodic oxidation conditions are selected, such fine holes are regularly arranged on the film surface, and a fine fibrous metal film is formed by plating in the fine holes. . The direction of the director of the liquid crystal L is generally aligned in one direction by a large number of fibrous metal plating films protruding from the anodized film. Specifically, these fine holes (that is, the fibrous metal plating film) are formed substantially perpendicular to the substrate so that the liquid crystal L is vertically aligned in the initial state.

  When such vertical alignment type alignment films 12 and 22 are formed, by using nematic liquid crystal having negative dielectric anisotropy as the liquid crystal L, it is possible to control the alignment of the liquid crystal L by voltage. That is, in the liquid crystal device 1 having such a configuration, the liquid crystal molecules L constituting the liquid crystal layer 30 are aligned in the alignment films 12 and 22 when no voltage is applied to the electrodes 11 and 21 (non-selected state and initial alignment state). When the substrate is oriented in a substantially vertical direction with respect to the substrates 10 and 20 by the orientation regulating force, and a voltage is applied between the two electrodes (selected state), the substrates 10 and 20 are inclined toward the surface direction. To work. Therefore, when the liquid crystal device 1 is sandwiched between two polarizing plates whose polarization directions are crossed, black display in the non-selected state and white display in the selected state can be realized.

[Method of manufacturing liquid crystal device]
Next, an example of a manufacturing method of the liquid crystal device of the present invention will be described with reference to FIGS. 2 is a schematic diagram showing an example of a process for forming an alignment film on a substrate, FIG. 3 is a schematic diagram showing the structure of an anodized film, and FIG. 4 is a method of plating a fibrous metal film on the pores of the anodized film. It is a schematic diagram which shows a process.

  In this method, first, as shown in FIG. 2, a metal film (anode) M1 that can be anodized is formed on the entire surface of the substrate 10 provided with the electrode 11, degreased with acetone or the like, and then a predetermined electrolytic solution. The metal film M1 is anodized using E. Here, a well-known thing can be used as the board | substrate 10 and the electrode 11. FIG. In this example, in order to perform transmissive display, for example, the substrate 10 is a translucent substrate such as glass, and the electrode 11 is a translucent conductive film such as ITO. A pixel switching circuit, a color filter, and the like can be formed on the substrate 10 as necessary. As the metal film M1, a so-called valve metal such as aluminum (Al), tungsten (Ta), titanium (Ti), magnesium (Mg), or an alloy thereof can be used. In particular, aluminum easily forms a regular pore arrangement structure as described above, and therefore, in this example, aluminum is used as the metal film M1. The metal film M1 is obtained by depositing, for example, aluminum having a purity of 99.99% on the substrate 10 by sputtering or the like to a thickness of about 200 nm. Further, as the electrolytic solution E, weakly acidic electrolytic solutions such as oxalic acid, phosphoric acid, sulfuric acid, and chromic acid are suitable. In this example, a 0.3 M (mol / l) sulfuric acid aqueous solution is used.

  Anodization is performed, for example, under the following conditions. Solution temperature of electrolyte E: 20 ° C., applied voltage: DC 30 V, cathode M2: platinum (Pt), anodization time: 1 hour. When such anodizing treatment is performed, fine holes are opened vertically on the surface of the metal film M1 by electrolysis reaction. As the reaction proceeds, a thin film 12a of aluminum oxide in which small holes (nanoholes) on the nanometer scale are regularly arranged is formed on the surface of the metal film M1. This is because the volume of the aluminum film is increased by oxidation, and the pores are rearranged in a self-organized manner so as to relieve the stress in the film. As the reaction proceeds further, the holes extend to the lower layer side while expanding the hole diameter, and finally a nanohole array penetrating to the underlying layer (substrate 10 or electrode 11) is formed.

FIG. 3 is a schematic diagram showing a schematic structure of the anodic oxide film 12a. FIG. 3 (a) is a partial perspective view thereof, and FIG. 3 (b) is a partial sectional view thereof. The anodic oxide film 12a has a structure in which a cylindrical alumina layer C having a certain size called a cell is closely packed. A micropore (pore) P having a uniform diameter is formed at the center of each cell C, and the micropore P has a unique geometric structure in which the micropores P are aligned perpendicularly to the film surface. The pitch (that is, the size of the cell C), the size, the depth, and the residual ratio of the underlying aluminum are changed by changing the concentration, temperature, voltage during anodic oxidation, current density, and time. Can be controlled. Further, by selecting appropriate conditions, it is possible to form a hole array structure in which these fine holes P are uniform in shape, size, depth, etc. and are regularly arranged at a constant pitch over a long distance. Is possible.
In this example, the base aluminum was made substantially zero by performing anodization for a long time (for example, 1 hour). By doing so, visible light can be transmitted and used for a transmissive display device.

  Next, as shown in FIG. 4, a fibrous metal film 12b is formed in each fine hole P of the anodic oxide film 12a by plating. In this example, the substrate 10 on which the anodic oxide film 12a is formed is placed in a 20 ° C. plating bath made of 1 mol / l nickel sulfate and 30 g / l boric acid, and nickel is put into the fine holes P by an AC electrodeposition method. Electrolytically deposited and protrudes from the fine holes P. Such protruding metal plating films 12b are arranged and formed at a constant density on the surface of the substrate, thereby having an alignment force in the direction along the extending direction of the metal plating film 12b. In this example, since such metal plating films 12b are regularly arranged on the substrate at a constant pitch, a uniform orientation state can be obtained in a wide range.

Next, the alignment film 22 is formed on the upper substrate 20 using the same method. Then, an empty cell is manufactured using these substrates 10 and 20, and liquid crystal having negative dielectric anisotropy is filled into the empty cell (for example, vacuum injection).
Thus, the liquid crystal device 1 is manufactured.

  As described above, according to the present embodiment, since the liquid crystal L is reliably aligned along the metal plating film 12b provided on the alignment films 12 and 22, high alignment ability can be realized. In addition, since the alignment films 12 and 22 are made of an inorganic material, they are superior in light resistance and solvent resistance compared to organic alignment films such as polyimide, and liquid crystal alignment is realized with fine columnar structures. (That is, it is a kind of shape alignment film), so that stable alignment can be obtained. Furthermore, since there is no shadowed portion as in oblique deposition, no alignment unevenness occurs. In addition, when the anodizing method is used, the pitch, size, shape, depth, etc. of the micropores can be adjusted according to the anodizing conditions, so that a stable alignment state can be easily realized by optimization. It is possible.

In this embodiment, a highly regular two-dimensional array structure is formed in the anodic oxide film 12a. However, this array structure does not necessarily need to be completely regular over the entire film surface. For example, the fine holes P as described above may be sparsely formed at irregular positions while maintaining the arrangement state. Moreover, each fine hole P does not need to be completely perpendicular to the film surface, and as long as it has directionality in the extending direction as a whole.
In the present embodiment, the two-dimensional array structure as described above is formed by optimizing the anodizing conditions, but the method of forming a regular pore structure is not limited to this. For example, a method in which a regular protrusion shape is previously formed on the surface of the metal film M1, and this is anodized can be considered. In this case, the oxide film grows with the protrusions as nuclei, and as a result, a porous anodic oxide film in which micropores are regularly arranged in two dimensions is formed.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the same members or parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. In this embodiment, the difference from the first embodiment is that a protective film for protecting the electrode is disposed between the electrode and the alignment film, and a metal plating film is formed in the hole of the anodized film. After that, the anodic oxide film is removed, and only the metal plating film, which is a conductive protrusion, is left as an alignment film. That is, in the first embodiment, the metal film M1 is directly formed on the surfaces of the electrodes 11 and 21 such as ITO. However, in the present embodiment, the surface of the electrodes 11 and 21 is formed in advance before the metal film M1 is formed. The protective films 13 and 23 having corrosion resistance against the electrolytic solution E (0.5 M oxalic acid in this example) are formed. By thus performing the anodic oxidation after forming the protective films 13 and 23, it is possible to prevent the underlying electrodes 11 and 21 from being corroded by the electrolytic solution E. The protective films 13 and 23 are made of an inorganic insulating film such as SiO ₂ . For this reason, even if a part of the metal film M1 remains without being oxidized in the anodic oxidation step, this does not cause a short circuit between the electrodes.

In this embodiment, since the anodic oxide film is removed by etching after the metal plating film is formed, the alignment film of the substrate 10 (20) is composed only of the fibrous metal plating film 15 (25). (See FIG. 6). Therefore, unlike a conventional alignment film made of an insulating material (such as an organic alignment film such as polyimide or an inorganic insulating alignment film such as a SiO ₂ oblique deposition film), this inorganic alignment is applied when a voltage is applied to the liquid crystal L. There is no problem that the films 15 and 25 function as a dielectric and a voltage drop occurs. That is, the voltage applied to the electrodes 11 and 21 can be fully applied to the liquid crystal L. The anodic oxide film can be removed by immersing the substrate in an etching solution containing 30 g / l chromium oxide and 35 ml / l phosphoric acid for 1 minute.
As described above, according to the present embodiment, the alignment stability and reliability of the liquid crystal device 2 can be further increased, and the yield in manufacturing the liquid crystal device 2 can be increased. Further, since the alignment films 15 and 25 are made of a conductive material, the electrical characteristics are excellent.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the same members or parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. This embodiment is different from the first embodiment only in that the fine holes of the anodic oxide film are arranged in an inclined state with respect to the substrate. In this example, these fine holes are formed in a state inclined at approximately 5 ° with respect to the normal line of the substrate, and the liquid crystal L is tilted in one direction in the initial state (the pretilt angle from the substrate surface is approximately 85 °). I try to let them.

  When such alignment films 16 and 26 are formed, by using a nematic liquid crystal having a negative dielectric anisotropy as the liquid crystal L, the alignment of the liquid crystal L can be controlled by voltage. In other words, in the liquid crystal device 2 having such a configuration, the liquid crystal molecules L constituting the liquid crystal layer 30 are aligned in the alignment films 16 and 26 when no voltage is applied to the electrodes 11 and 21 (non-selected state and initial alignment state). When the substrate is oriented in a substantially vertical direction with respect to the substrates 10 and 20 by the orientation regulating force, and a voltage is applied between the two electrodes (selected state), the substrates 10 and 20 are inclined toward the surface direction. To work. Therefore, if the liquid crystal device 3 is sandwiched between two polarizing plates whose polarization directions are crossed, black display in the non-selected state and white display in the selected state can be realized. At this time, in this embodiment, the liquid crystal L is tilted with respect to the substrate by the fine holes described above, so that the liquid crystal L is uniformly tilted in the tilt direction in the selected state. For this reason, it is possible to prevent a plurality of regions (reverse domains) having different tilt directions from being formed, and it is possible to suppress display unevenness such as disclination occurring at the boundary between them.

[Method of manufacturing liquid crystal device]
Next, an example of a method for manufacturing a liquid crystal device of the present invention will be described with reference to FIGS. FIG. 8 is a schematic view showing an example of a process for forming an alignment film on the substrate, FIG. 9 is a schematic view showing the structure of the anodized film, and FIG. 10 is a method of plating a fibrous metal film on the pores of the anodized film. It is a schematic diagram which shows a process.

  In this method, first, as shown in FIG. 8, a metal film (anode) M1 that can be anodized is formed on the entire surface of the substrate 10 provided with the electrode 11, and after degreasing treatment with acetone or the like, a predetermined electrolytic solution is obtained. Using E, the metal film M1 is anodized in a magnetic field H ′ parallel to the substrate surface. Here, a well-known thing can be used as the board | substrate 10 and the electrode 11. FIG. In this example, in order to perform transmissive display, for example, the substrate 10 is a translucent substrate such as glass, and the electrode 11 is a translucent conductive film such as ITO. A pixel switching circuit, a color filter, and the like can be formed on the substrate 10 as necessary. As the metal film M1, a so-called valve metal such as aluminum (Al), tungsten (Ta), titanium (Ti), magnesium (Mg), or an alloy thereof can be used. In particular, aluminum easily forms a regular pore arrangement structure as described above, and therefore, in this example, aluminum is used as the metal film M1. The metal film M1 is obtained by depositing, for example, aluminum having a purity of 99.99% on the substrate 10 by sputtering or the like to a thickness of about 200 nm. Further, as the electrolytic solution E, weakly acidic electrolytic solutions such as oxalic acid, phosphoric acid, sulfuric acid, and chromic acid are suitable. In this example, a 0.3 M (mol / l) sulfuric acid aqueous solution is used.

Anodization is performed, for example, under the following conditions. Electrolyte E temperature: 20 ° C., magnetic field H ′: 2T (20 kG), applied voltage: DC 30 V, cathode M2: platinum (Pt), anodization time: 1 hour. When such anodizing treatment is performed, fine holes are opened on the surface of the metal film M1 by electrolysis. As the reaction proceeds, a thin film 16a of aluminum oxide in which small holes (nanoholes) on the nanometer scale are regularly arranged is formed on the surface of the metal film M1. This is because the volume of the aluminum film is increased by oxidation, and the pores are rearranged in a self-organized manner so as to relieve the stress in the film. As the reaction proceeds further, the holes extend to the lower layer side while expanding the hole diameter, and finally a nanohole array penetrating to the underlying layer (substrate 10 or electrode 11) is formed.
By the way, such fine holes usually open in a direction perpendicular to the substrate. However, in this embodiment, since such anodization is performed in a magnetic field parallel to the substrate surface, the fine holes are opened obliquely with respect to the substrate. In other words, anodic oxidation attracts oxygen ions in the electrolyte solution to the surface of the metal film by electrical action and oxidizes the metal surface. Therefore, when anodic oxidation is performed in a magnetic field, Anisotropy occurs in the movement, and the growth direction of the oxide film becomes directional. For example, when a magnetic field is applied in a direction non-parallel to the normal line of the substrate, the oxide film grows in a direction inclined from the normal direction of the substrate toward the azimuth direction side of the magnetic field. In this example, since the magnetic field is applied in a direction parallel to the substrate surface, the micro hole is opened in a state of being inclined toward the direction of the magnetic field.

  9A and 9B are schematic views showing a schematic structure of the anodic oxide film 16a. FIG. 9A is a partial perspective view thereof, and FIG. 9B is a partial cross-sectional view thereof. This anodic oxide film 16a has a structure in which a cylindrical alumina layer C having a certain size called a cell is closely packed. A micropore (pore) P having a uniform diameter is formed at the center of each cell C, and the micropore P has a unique geometric structure in which the micropores P are aligned perpendicularly to the film surface. The pitch (that is, the size of the cell C), the size, the depth, and the residual ratio of the underlying aluminum are changed by changing the concentration, temperature, voltage during anodic oxidation, current density, and time. Can be controlled. Further, by selecting appropriate conditions, it is possible to form a hole array structure in which these fine holes P are uniform in shape, size, depth, etc. and are regularly arranged at a constant pitch over a long distance. Is possible.

In this embodiment, since the anodic oxide film is grown obliquely by the magnetic field H ′, each fine hole P is inclined at a constant angle θ with respect to the normal line of the substrate. This inclination angle θ can be controlled by changing the magnitude of anisotropy in the growth process of the oxide film, that is, the strength of the magnetic field H ′. For example, when the magnetic field H ′ is 1T (10 kG) or more, the fine holes P are inclined with respect to the substrate normal. In this example, the magnetic field H ′ is 2T, and the inclination angle θ of the fine hole P is about 5 °.
In this example, the base aluminum was made substantially zero by performing anodization for a long time (for example, 1 hour). By doing so, visible light can be transmitted and used for a transmissive display device.

  Next, as shown in FIG. 10, a fibrous metal film 16b is formed in each fine hole P of the anodic oxide film 16a by plating. In this example, the substrate 10 on which the anodic oxide film 16a is formed is placed in a 20 ° C. plating bath made of 1 mol / l nickel sulfate and 30 g / l boric acid, and nickel is put into the fine holes P by AC electrodeposition. Electrolytically deposited and protrudes from the fine holes P. Such protruding metal plating films 16b are arranged and formed on the surface of the substrate at a constant density, so that the metal plating films 16b have an alignment force in a direction along the extending direction of the metal plating film 16b. In this example, since such metal plating films 12b are regularly arranged on the substrate at a constant pitch, a uniform orientation state can be obtained in a wide range.

Next, the alignment film 26 is formed on the upper substrate 20 using the same method. Then, an empty cell is manufactured using these substrates 10 and 20, and liquid crystal having negative dielectric anisotropy is filled into the empty cell (for example, vacuum injection).
Thus, the liquid crystal device 3 is manufactured.

  As described above, in this embodiment, since anodic oxidation is performed in a magnetic field, uniform tilt alignment can be realized. Further, by controlling the direction and magnitude of this magnetic field, it is possible to control the tilt of the fine hole P (that is, the tilt of the liquid crystal L).

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the same members or parts as those in the third embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. This embodiment differs from the third embodiment in that a protective film for protecting the electrode is disposed between the electrode and the alignment film, and a metal plating film is formed in the hole of the anodized film After that, the anodic oxide film is removed, and only the metal plating film, which is a conductive protrusion, is left as an alignment film. That is, in the third embodiment, the metal film M1 is directly formed on the surfaces of the electrodes 11 and 21 such as ITO. However, in the present embodiment, the surface of the electrodes 11 and 21 is formed in advance before the metal film M1 is formed. The protective films 13 and 23 having corrosion resistance against the electrolytic solution E (0.5 M oxalic acid in this example) are formed. By thus performing the anodic oxidation after forming the protective films 13 and 23, it is possible to prevent the underlying electrodes 11 and 21 from being corroded by the electrolytic solution E. The protective films 13 and 23 are made of an inorganic insulating film such as SiO ₂ . For this reason, even if a part of the metal film M1 remains without being oxidized in the anodic oxidation step, this does not cause a short circuit between the electrodes.

In this embodiment, since the anodic oxide film is removed by etching after the metal plating film is formed, the alignment film of the substrate 10 (20) is composed only of the fibrous metal plating film 17 (27). (See FIG. 12). Therefore, unlike a conventional alignment film made of an insulating material (such as an organic alignment film such as polyimide or an inorganic insulating alignment film such as a SiO ₂ oblique deposition film), this inorganic alignment is applied when a voltage is applied to the liquid crystal L. There is no problem that the films 17 and 27 function as a dielectric and a voltage drop occurs. That is, the voltage applied to the electrodes 11 and 21 can be fully applied to the liquid crystal L. The anodic oxide film can be removed by immersing the substrate in an etching solution containing 30 g / l chromium oxide and 35 ml / l phosphoric acid for 1 minute.
As described above, according to the present embodiment, the alignment stability and reliability of the liquid crystal device 4 can be further increased, and the yield in manufacturing the liquid crystal device 4 can also be increased. Further, since the alignment films 17 and 27 are made of a conductive material, the electrical characteristics are excellent.

[Electronics]
Next, an electronic device including the above-described liquid crystal device will be described. Here, as an example, a transmissive projection display device including the liquid crystal device as a light modulation unit will be described.
FIG. 13 is a diagram showing a schematic configuration of a three-plate type color liquid crystal projector which is an example of the projection display device of this example. In this figure, 510 is a light source, 513 and 514 are dichroic mirrors, 515, 516 and 517 are reflection mirrors, 518 is an entrance lens, 519 is a relay lens, 520 is an exit lens, 522, 523 and 524 are transmissive liquid crystal light valves. Reference numeral 525 denotes a cross dichroic prism, and 526 denotes a projection lens.

  The light source 510 includes a lamp 511 such as a metal halide and a reflector 512 that reflects the light of the lamp. The blue light and green light reflecting dichroic mirror 513 transmits red light of the light flux from the light source 510 and reflects blue light and green light. The transmitted red light is reflected by the reflection mirror 517 and is incident on the red light liquid crystal light valve 522 provided with the liquid crystal device of the embodiment. On the other hand, green light out of the color light reflected by the dichroic mirror 513 is reflected by the dichroic mirror 514 that reflects green light, and enters the green light liquid crystal light valve 523 provided with the liquid crystal device of the embodiment. Note that the blue light also passes through the second dichroic mirror 514. For blue light, in order to compensate for the difference in optical path length from green light and red light, a light guide means 521 comprising a relay lens system including an incident lens 518, a relay lens 519, and an exit lens 520 is provided. Through this, the blue light is incident on the blue light liquid crystal light valve 524 provided with the liquid crystal device of the embodiment. Incident-side polarizing plates 522a, 523a, and 524a and outgoing-side polarizing plates 522b, 523b, and 524b are installed before and after the red light liquid crystal light valve 522, the green light liquid crystal light valve 523, and the blue light liquid crystal light valve 524, respectively. ing. The light that has been linearly polarized by the incident-side polarizing plate is modulated by the liquid crystal light valve and then passes through the outgoing-side polarizing plate. However, since only light in the vibration direction determined at this time can be transmitted, the light can be adjusted.

  The three color lights modulated by each liquid crystal light valve and two polarizing plates are incident on the cross dichroic prism 525. In this prism, four right-angle prisms are bonded, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in a cross shape on the inner surface. These dielectric multilayer films combine the three color lights to form light representing a color image. The synthesized light is projected onto the screen 527 by the projection lens 526 which is a projection optical system, and the image is enlarged and displayed.

Since the projection type display device of this example includes the liquid crystal device of the above-described embodiment, it is excellent in mass productivity, has high alignment regulating power for the liquid crystal molecules constituting the liquid crystal layer, and has durability against light and heat. It is an excellent and highly reliable display device. In this example, when a polyimide organic film is conventionally used for the alignment film, the lifetime of 2000 hours can be increased to 10,000 hours or more.
In this example, the liquid crystal device of the embodiment is used for each of the liquid crystal light valves for red light, green light, and blue light. However, the liquid crystal device need not be applied to all liquid crystal light valves. If applied to at least one of the liquid crystal light valves, durability can be improved. In this case, it is particularly effective to apply to a liquid crystal light valve for blue light having a high light energy.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described with reference to FIG. In the present embodiment, the same members or parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. In this embodiment, the difference from the first embodiment is that the electrode on the lower substrate 10 side is a high-reflection metal reflective electrode 14 and the alignment film on the upper substrate 20 side is an organic alignment film 24 such as polyimide. Only. That is, in the first embodiment, another metal film M1 is formed on the surfaces of the electrodes 11 and 21, and all the metal film M1 is anodized to make the surfaces of the electrodes 11 and 21 porous. Inorganic alignment films 12 and 22 were formed. On the other hand, in the liquid crystal device 5 of the present embodiment, the metal film M1 as an anode is directly formed on the substrate surface without providing the electrode 11 on the substrate 10. In the step of forming the anodic oxide film, only the surface of the metal film M1 is anodized, and the other metal film M1 is left as an electrode 14 for applying a voltage to the liquid crystal L. By doing so, it is not necessary to separately form an electrode for liquid crystal alignment, and the process can be simplified.

In addition, since the alignment film on the upper substrate side is the organic alignment film 24 having excellent alignment ability, the initial alignment state after filling the liquid crystal (for example, the alignment state immediately after liquid crystal injection) can be stabilized. That is, in the shape alignment film that aligns the liquid crystal L by the shape effect like the inorganic alignment film 12, the liquid crystal L tends to be in a metastable alignment state, and the alignment state immediately after filling the liquid crystal tends to be unstable. For this reason, in order to make the liquid crystal L transition to the most stable alignment state, in addition to the alignment force due to the shape effect described above, it is desirable to apply some alignment force that assists this. On the other hand, in an organic alignment film such as polyimide, the alignment of the liquid crystal L is strongly regulated by the intermolecular force between the organic alignment film and the liquid crystal L, so that the transition to the stable alignment is more reliable than the inorganic alignment film 12 described above. The time until the transition is performed is short. For this reason, by using the upper substrate 20 side as the organic alignment film 24 as in this embodiment, the alignment regulating force of the organic alignment film 24 can be indirectly transmitted to the lower substrate 10 side via the liquid crystal layer 30. As a result, the alignment state of the liquid crystal L in the vicinity of the inorganic alignment film 12 can be reliably shifted to the most stable state in a short time.
Thus, according to this embodiment, the alignment stability and reliability of the liquid crystal device 5 can be further improved.

[Sixth Embodiment]
Next, a sixth embodiment of the present invention will be described with reference to FIG. In the present embodiment, the same members or parts as those in the fifth embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. The present embodiment is different from the fifth embodiment only in that the fine holes of the anodic oxide film on the lower substrate 10 side are arranged in an inclined state with respect to the substrate. In this example, the tilt angle of the liquid crystal L is adjusted to approximately 5 ° (that is, the liquid crystal L is tilted approximately 5 ° from the parallel alignment with respect to the substrate in the non-selected state) by adjusting the conditions such as the magnetic field when anodizing. Orientation). Then, nematic liquid crystal having positive dielectric anisotropy is used for the liquid crystal L, and this is hybrid-aligned between the upper and lower substrates.
Thus, also in this embodiment, the alignment stability and reliability of the liquid crystal device 6 can be further improved.

[Electronics]
Next, an electronic device including the above-described liquid crystal device will be described. Here, as an example, a reflection type projection display device including the liquid crystal device as light modulation means will be described. FIG. 16 is a diagram showing a schematic configuration of a three-plate type color liquid crystal projector which is an example of the projection display device of this example.

  The liquid crystal projector of this example includes a light source unit 710 disposed along the system optical axis L, an integrator lens 720, and a polarization conversion device 730 that is roughly composed of a polarization conversion element 730, and an S-polarized light beam emitted from the polarization illumination device 700. Is reflected by the S-polarized light beam reflecting surface 741, and the dichroic mirror 742 that separates the blue light (B) component from the light reflected from the S-polarized light beam reflecting surface 741 of the polarized beam splitter 740 is separated. The reflective liquid crystal light valve 745B that modulates the blue light (B) is separated, and the dichroic mirror 743 that reflects and separates the red light (R) component out of the luminous flux after the blue light is separated. Reflective liquid crystal light valve 745R that modulates red light (R) and the remaining light that passes through dichroic mirror 743 The light modulated by the reflective liquid crystal light valve 745G that modulates the color light (G) and the three reflective liquid crystal light valves 745R, 745G, and 745B are synthesized by the dichroic mirrors 743 and 742, and the polarization beam splitter 740. The projection optical system 750 includes a projection lens that projects the combined light onto the screen 760. Each of the three reflective liquid crystal light valves 745R, 745G, and 745B uses the liquid crystal device described in the above embodiment.

The randomly polarized light beam emitted from the light source unit 710 is divided into a plurality of intermediate light beams by the integrator lens 720, and then the polarized light beam is substantially aligned by the polarization conversion element 720 having the second integrator lens on the light incident side. After being converted into a kind of polarized light beam (S-polarized light beam), it reaches the polarization beam splitter 740. The S-polarized light beam emitted from the polarization conversion element 730 is reflected by the S-polarized light beam reflecting surface 741 of the polarization beam splitter 740, and among the reflected light beams, the blue light (B) light beam is the blue light of the dichroic mirror 742. Reflected by the reflective layer and modulated by the reflective liquid crystal light valve 745B. Of the light beams transmitted through the blue light reflection layer of the dichroic mirror 742, the red light (R) light beam is reflected by the red light reflection layer of the dichroic mirror 743 and modulated by the reflective liquid crystal light valve 745R. . On the other hand, the luminous flux of green light (G) transmitted through the red light reflecting layer of the dichroic mirror 743 is modulated by the reflective liquid crystal light valve 745G. As described above, the color light is modulated by the reflective liquid crystal light valves 745R, 745G, and 745B.
Of the color light reflected from the pixels of these liquid crystal panels, the S-polarized component does not pass through the polarization beam splitter 740 that reflects S-polarized light, and the P-polarized component passes through it. An image is formed by the light transmitted through the polarization beam splitter 740.

Since the projection type display device of this example includes the liquid crystal device of the above-described embodiment, it is excellent in mass productivity, has high alignment regulating power for the liquid crystal molecules constituting the liquid crystal layer, and has durability against light and heat. It is an excellent and highly reliable display device.
In this example, the liquid crystal device of the embodiment is used for each of the liquid crystal light valves for red light, green light, and blue light. However, the liquid crystal device need not be applied to all liquid crystal light valves. If applied to at least one of the liquid crystal light valves, durability can be improved. In this case, it is particularly effective to apply to a liquid crystal light valve for blue light having a high light energy.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but it goes without saying that the present invention is not limited to such examples. For example, the liquid crystal device according to each of the above embodiments can be mounted not only on the projection display device described above but also on various electronic devices. Examples of such electronic devices include mobile phones, electronic books, personal computers, digital still cameras, LCD televisions, viewfinder type or monitor direct view type video tape recorders, car navigation devices, pagers, electronic notebooks, calculators, word processors, workstations. There are devices such as videophones, POS terminals, touch panels, etc., and the liquid crystal device can be suitably used as these image display means. Further, the shapes and combinations of the constituent members shown in the above-described examples are merely examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

1 is a schematic cross-sectional view showing a configuration of a liquid crystal device according to a first embodiment of the present invention. The figure for demonstrating the manufacturing method of a liquid crystal device equally. The perspective view which shows typically the structure of the anodic oxide film of a liquid crystal device. The figure which shows the process of plating and forming a metal film in the micropore of an anodic oxide film. The cross-sectional schematic diagram which shows the structure of the liquid crystal device which concerns on 2nd Embodiment of this invention. FIG. 3 is a schematic cross-sectional view showing the structure of the alignment film of the liquid crystal device. FIG. 6 is a schematic cross-sectional view illustrating a configuration of a liquid crystal device according to a third embodiment of the present invention. The figure for demonstrating the manufacturing method of a liquid crystal device equally. The perspective view which shows typically the structure of the anodic oxide film of a liquid crystal device. The figure which shows the process of plating and forming a metal film in the micropore of an anodic oxide film. FIG. 10 is a schematic cross-sectional view illustrating a configuration of a liquid crystal device according to a fourth embodiment of the invention. FIG. 3 is a schematic cross-sectional view showing the structure of the alignment film of the liquid crystal device. 1 is a diagram showing a schematic configuration of a projection display device that is an example of an electronic apparatus of the present invention. FIG. 10 is a schematic cross-sectional view illustrating a configuration of a liquid crystal device according to a fifth embodiment of the invention. Sectional schematic diagram which shows the structure of the liquid crystal device which concerns on 6th Embodiment of this invention. 1 is a diagram showing a schematic configuration of a projection display device that is an example of an electronic apparatus of the present invention.

Explanation of symbols

1, 2, 3, 4, 5, 6 ... liquid crystal device, 10, 20 ... substrate, 11, 14, 21 ... electrode, 12, 16, 22, 26 ... inorganic alignment film, 12a , 16a ... anodized film, 12b, 16b ... metal plating film, 15, 17, 25, 27 ... conductive protrusion (inorganic alignment film), 13, 23 ... protective film, 24 ... Organic alignment film, 30 ... Liquid crystal layer, E ... Electrolyte, L ... Liquid crystal, M1 ... Metal film, P ... Micropore

Claims (19)

A method of manufacturing a liquid crystal device in which a liquid crystal is sandwiched between a pair of opposing substrates,
Forming an inorganic alignment film on the surface of at least one of the pair of substrates;
Forming the inorganic alignment film includes forming a metal film on the surface of the one substrate;
Anodizing the metal film using an electrolytic solution to form an anodic oxide film having a plurality of micropores on the surface of the one substrate; and electrolytic plating to each of the plurality of micropores. And a step of forming a conductive protrusion that covers the inside of the fine hole and a part of which protrudes from the surface of the anodic oxide film.   The method of manufacturing a liquid crystal device according to claim 1, wherein the plurality of fine holes are two-dimensionally arranged.   The method of manufacturing a liquid crystal device according to claim 2, wherein the plurality of micro holes are formed substantially perpendicular to the one substrate.   The step of forming the anodic oxide film is a step of applying a magnetic field parallel or oblique to the one substrate and forming the plurality of micro holes in an inclined state with respect to the one substrate. The method for manufacturing a liquid crystal device according to claim 1, wherein the liquid crystal device is manufactured.   The method for manufacturing a liquid crystal device according to claim 1, wherein the metal film is made of aluminum.   The method of manufacturing a liquid crystal device according to claim 1, wherein the electrolytic solution is an acidic electrolytic solution.   The step of forming the anodized film is a process of anodizing only the surface of the metal film and leaving the other metal film as an electrode for applying a voltage to the liquid crystal. The manufacturing method of the liquid crystal device of any one of 1-6. An electrode for applying a voltage to the liquid crystal on the surface of the one substrate;
The formation step of the inorganic alignment film includes a step of forming a protective film for protecting the surface of the electrode between the electrode and the metal film. 2. A method for manufacturing a liquid crystal device according to item 1.   The method for manufacturing a liquid crystal device according to claim 1, wherein the forming step of the inorganic alignment film includes a step of removing the anodic oxide film after forming the conductive protrusions. .   The method for manufacturing a liquid crystal device according to claim 1, further comprising a step of forming the inorganic alignment film on a surface of the other substrate of the pair of substrates.   The method for manufacturing a liquid crystal device according to claim 1, further comprising a step of forming an organic alignment film on a surface of the other substrate of the pair of substrates. A liquid crystal device having a liquid crystal sandwiched between a pair of opposing substrates,
An inorganic alignment film comprising a plurality of conductive protrusions for aligning liquid crystal on the surface of at least one of the pair of substrates ;
The plurality of conductive protrusions are two-dimensionally arranged in a state of being separated from each other,
Each of the conductive protrusions is disposed at a position that is the center of each of a plurality of regions that are closely packed with each other in the plane of the one substrate . The liquid crystal device according to claim 12 , wherein the plurality of conductive protrusions are formed substantially perpendicular to the one substrate. The liquid crystal device according to claim 12 , wherein the plurality of conductive protrusions are formed to be inclined with respect to the one substrate. It said liquid crystal, characterized in that the dielectric anisotropy is negative nematic liquid crystal, the liquid crystal device according to claim 13 or 14, wherein. Wherein the plurality of sizes of conductive protrusions, shape, wherein the height is substantially equal configuration, the liquid crystal device according to any one of claims 12-15. Characterized by comprising the inorganic alignment film on the surface of the substrate of both of the pair of substrates, the liquid crystal device according to any one of claims 12 to 16. The liquid crystal device according to any one of claims 12 to 16 , wherein an organic alignment film is provided on a surface of the other substrate of the pair of substrates.   An electronic apparatus comprising a liquid crystal device manufactured using the method according to claim 1.

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