JP2005338554A - Method for manufacturing liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a liquid crystal display that has neither remaining liquid nor a stain and is free of problems of a alkali residue. <P>SOLUTION: The method for manufacturing the liquid crystal display includes the stage of forming a 1st alignment film 29a over the entire surface of a pixel electrode 11, and that of discharging a solution containing a constituent material of a 2nd alignment film 29b onto the 1st alignment film 29a of either a transmission type electrode 11b or a reflection type electrode 11a to form the 2nd alignment film 29b different in pretilt angle from the 1st alignment film 29a. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a liquid crystal display device, and more particularly to a method for manufacturing a liquid crystal display device in which a transmission portion and a reflection portion are provided in one pixel region.

In recent years, liquid crystal display devices operating in the OCB mode have attracted attention. The OCB mode is a mode in which gradation display is performed by utilizing the fact that liquid crystal molecules are in a bent alignment state when a voltage is applied, and the pretilt angle on one alignment film side gradually changes as a voltage is further applied. This OCB mode is characterized in that it can respond at high speed and has a high viewing angle.
Recently, as described in Patent Document 1, among the liquid crystal layers sandwiched between a pair of alignment films, one alignment film is in parallel alignment, and the other alignment film is in vertical alignment. Similar modes of the OCB mode in which the molecules are hybrid oriented have also been proposed.

  Therefore, a transmission region that operates in the OCB mode and a reflection region that operates in a mode similar to the OCB mode are provided in one pixel region, and display between the transmission region and display by the reflection region can be switched according to the use environment. A transflective liquid crystal display device has been developed.

By the way, in the modes similar to the OCB mode and the OCB mode, since the alignment patterns of the liquid crystal molecules are different, it is necessary to separately form the alignment film in the transmissive region and the alignment film in the reflective region. Specifically, among the pair of substrates sandwiching the liquid crystal layer, an alignment film having a small pretilt angle is formed on the entire surface of the substrate on the common electrode side, and in the so-called active matrix substrate of the pair of substrates, the pretilt is formed in the transmission region. It is necessary to form an alignment film having a small angle and to form an alignment film having a large pretilt angle in the reflective region. For example, an example in which the above-described configuration is tried by forming an alignment film made of an inorganic material on the entire surface of an active matrix substrate and then forming an alignment film made of an organic material only in the transmission region has been reported ( For example, the following nonpatent literature 1).
JP-A-9-146086 Y. Koike et. al Japan Display Digest, 798 (1992)

  However, in the method described in Non-Patent Document 2, an alignment film having a low pretilt angle is formed only in the transmission region by applying an organic material as a raw material for the alignment film to the entire surface of the substrate and then performing etching or the like. However, there is a problem that liquid residue, spots, etc. are likely to occur on the alignment film. In addition, since an alkaline solution is used as an etchant for the alignment film, there is a problem that the current rise (particularly during high temperature operation) of the liquid crystal layer due to residual alkali occurs and the display disappears.

  Recently, a field sequential method (FS method) that uses a light emitting diode as a light source and enables full color display without using a color filter has been studied. However, since this FS method requires high-speed switching, TFT active There is also a problem that the drive system is adopted and the influence of the previous residual alkali is large.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a method for manufacturing a liquid crystal display device in which no liquid residue or spots are generated and there is no problem of residual alkali.

In order to achieve the above object, the present invention employs the following configuration.
The method for producing a liquid crystal display device of the present invention comprises a liquid crystal layer and a pair of transparent substrates facing each other with the liquid crystal layer interposed therebetween, and a common electrode and a common alignment film are provided on the inner surface side of the one transparent substrate. A plurality of switching elements and a plurality of pixel electrodes respectively connected to the switching elements are provided on the inner surface side of the other transparent substrate, and the pixel electrodes are incident from the one substrate side. A liquid crystal display device comprising: a reflective electrode that reflects the reflected light; and a transmissive electrode that transmits light from the other substrate side to the one substrate side, over the entire surface of the pixel electrode. A step of forming a first alignment film, and a pretilt angle by discharging a solution containing a constituent material of the second alignment film onto the first alignment film of either the transmissive electrode or the reflective electrode. Said Forming an alignment film is different from the second alignment film, characterized by comprising comprises a.

  In the above configuration, a so-called inkjet method is employed in which a solution containing a constituent material of the second alignment film is discharged onto the first alignment film to form the second alignment film. In this method, the second alignment film is formed by evaporating only the solvent after discharging the solution. As a result, there is no problem of liquid residue and spot generation as in the conventional method, and alkali residue does not occur. Moreover, the formation position of the second alignment film can be precisely controlled by using the ink jet method.

In the method for manufacturing a liquid crystal display device of the present invention, the second alignment film is formed on the transmission electrode, and the pretilt angle of the first alignment film is set larger than the pretilt angle of the second alignment film. It is preferable.
In the method for manufacturing a liquid crystal display device of the present invention, the second alignment film is formed on the reflective electrode, and the pretilt angle of the first alignment film is set smaller than the pretilt angle of the second alignment film. It is preferable.
In the method of manufacturing a liquid crystal display device according to the present invention, the reflective electrode is formed on a convex portion provided on the other substrate, and the transmissive electrode is formed in a concave portion corresponding to the convex portion. It is preferable that

  A solution receiving layer impregnated with the solution may be provided between the first alignment film and the second alignment film. The first alignment film may be used as a solution receiving layer.

  As described above, according to the method for manufacturing a liquid crystal display device of the present invention, when selectively forming regions having different pretilt angles, an alignment film can be formed quickly and in a necessary pattern accuracy without contact. it can. In particular, when the transmissive pixel electrode serving as the transmissive portion is a recess that easily receives the solution, the first alignment film formed in advance functions as a solution receiving layer. Pattern accuracy is greatly improved and pinholes can be prevented from occurring. Further, since an alkaline etchant is not used, residual alkali can be reduced, and voltage holding characteristics of the liquid crystal layer can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings below, the film thicknesses and dimensional ratios of the respective components are appropriately changed for easy understanding of the drawings.

1 and 2 show an example of a transflective liquid crystal display device (liquid crystal display device) according to the present invention. As shown in FIG. 1, the transflective liquid crystal display device A includes a liquid crystal panel (liquid crystal cell) 1 as a main body and a backlight 4 disposed on the back side of the liquid crystal panel 1. .
As shown in FIGS. 1 and 2, the liquid crystal panel 1 includes an active matrix substrate 2 on the side where the switching element 10 is formed, a counter substrate 3 provided to face the active matrix substrate 2, and the substrates 2 and 3. And a liquid crystal layer 5 as a light modulation layer that is held.

The counter substrate 3 is configured by sequentially arranging a color filter 42, a common electrode 43, and a common alignment film 44 inside a substrate 41 (one transparent substrate) (on the liquid crystal layer 5 side). The active matrix substrate 2 includes a substrate 6 (the other transparent substrate), a switching element 10 formed on the substrate 6, a pixel electrode 11 connected to the switching element 10, a reflector 20, and a pixel electrode 11. And an alignment film 29 laminated thereon. The liquid crystal layer 5 is disposed between the alignment films 29 and 44.
The pixel electrode 11 includes a transmissive electrode 11a stacked on the substrate 6 and a reflective electrode 11b that constitutes the reflector 20 together with the insulating film 20a. Each of the transmissive electrode 11 a and the reflective electrode 11 b is connected to the switching element 10.

  Further, on the outer surface side of the counter substrate 3, a phase difference plate (not shown) and a polarizing plate are sequentially laminated. In addition, a retardation plate (not shown) and a polarizing plate are laminated on the outer surface side of the active matrix substrate 2.

  The transflective liquid crystal display device A having the above configuration operates in a reflection mode in which the backlight 4 is not turned on when sufficient external light is obtained, and the backlight 4 is turned on in an environment where no external light is obtained. To operate in transparent mode.

The liquid crystal display device of the present invention operates in the R-OCB mode in the reflection mode, and operates in the OCB mode in the transmission mode.
In the reflection mode, the light incident on the polarizing plate and the retardation plate on the counter substrate 3 side is linearly polarized by this polarizing plate, and further, the light converted into predetermined elliptical polarization by the retardation plate passes through the liquid crystal layer 5. And reflected by the reflector. Then, after passing through the retardation plate on the counter substrate 3 side again, the optical conditions (axial direction of the polarizing plate / retardation plate, axial direction of the retardation plate) Phase difference value setting, etc.) are set.
On the other hand, in the transmission mode, the light emitted from the backlight 4 is incident on the polarizing plate and the retardation plate on the active matrix substrate 2 side, and is converted into linearly polarized light by the polarizing plate and predetermined elliptically polarized light by the retardation plate. Then, the light passing through the liquid crystal layer 5 and another retardation plate on the counter substrate 3 side, and the light passing through the retardation plate and incident on the polarizing plate at this time is almost in the linear polarization state from the elliptical polarization state. The optical conditions of the polarizing plate or the retardation plate (the axial direction of the polarizing plate / retardation plate, the retardation value of the retardation plate, etc.) are set so as to be in a state.

  A plurality of scanning lines and signal lines (not shown) are formed on the substrate 6 along the row direction and the column direction so as to be electrically insulated, and the vicinity of the intersection of each scanning line and signal line is shown in FIG. Thus, a TFT (switching element) 10 is formed. In the present invention, a region where the pixel electrode 11 (11a, 11b) is formed on the substrate 6 is called a pixel region M, and a region where the TFT 10 is formed, a region where a scanning line and a signal are formed are respectively element regions. This is called a wiring area.

The TFT 10 has an inverted staggered structure, and a gate electrode 13, a gate insulating film 15, an i-type semiconductor layer 14, a source electrode 17 and a drain electrode 18 are formed in this order from the bottom layer of the substrate 6. An etching stopper layer 9 is formed between the source electrode 17 and the drain electrode 18.
That is, a part of the scanning line is extended to form the gate electrode 13, and the island-like semiconductor layer 14 is formed on the gate insulating film 15 covering the gate line 13 so as to straddle the gate electrode 13 in plan view. A source electrode 17 is formed on one end of the i-type semiconductor layer 14 via an n-type semiconductor layer 16, and a drain electrode 18 is formed on the other end via an n-type semiconductor layer 16.

  In addition, a transmissive electrode 11a (pixel electrode 11) made of a transparent electrode material such as ITO is formed directly on the substrate body 6 at the center of a rectangular region surrounded by the scanning lines and signal lines. ing. Thus, the transmission electrode 11a is formed at the same plane position as the previous gate electrode 13. These transmissive electrodes 11a are directly connected to the connecting portion 17a at one end of the source electrode 17 connected so as to ride on the one end 11c, and are formed in a rectangular shape in plan view.

Further, an insulating film 20a (convex portion) made of an organic material is laminated on the substrate 6, and a reflective electrode 11b (pixel electrode 11) made of a highly reflective metal material such as Al or Ag is laminated on the insulating film 20a. Is formed. The insulator 20a and the reflective electrode 11b constitute a reflector 20.
The reflective electrode 11b is formed on the insulating film 20a so as to have a rectangular shape in plan view that is slightly smaller than a region surrounded by the previous scanning line and signal line.

  The insulating film 20a is an organic insulating film made of acrylic resin, polyimide resin, benzocyclobutene polymer (BCB) or the like, and strengthens the protective function of the TFT 10. The insulating film 20a is laminated on the substrate 6 relatively thickly to ensure insulation between the transmissive electrode 11a, the TFT 10, and various wirings, and to prevent a large parasitic capacitance from being generated between the transmissive electrode 11a. The step structure on the substrate 6 formed by the TFT 10 and various wirings is flattened by the thick insulating film 20a.

  Next, in the insulating film 20a, a contact hole 21 is provided so as to reach one end portion 17a of each source electrode 17, and a recess 22 is formed so as to be positioned on the previous transmission electrode 11a. A planar through hole 23 is formed in the reflective electrode 11b corresponding to the position where the recess 22 is formed so as to match the opening 22a of the recess 22. These recesses 22 are formed so that most of the insulating film 20a is removed in the depth direction and only a part of the insulating film 20a is left as a coating layer 20b on the bottom 22b side, and the planar shape of the recess 22 is the same as that of the transmissive electrode 11a. It is formed in a strip shape slightly shorter than the transmission electrode 11a so as to correspond to the planar shape.

  In each pixel region, the formation region of the recess 22 is a transmissive portion 30 that transmits incident light (light emitted from the backlight 4) from the active matrix substrate 2 side, and the non-perforated portion of the reflective electrode 11b. A portion where the through hole 23 is not formed is a reflecting portion 35 that reflects incident light from the counter substrate 3 side.

  Further, one of the pixel electrodes 11 (11a, 11b) corresponds to approximately one pixel region, and the area of the through hole 23 corresponds to the light passage region in the transmissive display, so that the entire area of the previous pixel electrode 11 It is preferable that the area ratio of the through-holes 23 in the range of 20 to 70%, for example, 50%. Furthermore, in this embodiment, only one through hole 23 is formed in the pixel electrode 11, but a plurality of through holes may be formed in the pixel electrode 11. In this case, the total area of the plurality of through holes is set to a range of 20 to 60% of the entire area of the pixel electrode 11. Of course, in that case, a concave portion is provided under each through hole in accordance with the formation position of the plurality of through holes.

  In the contact hole 21 provided in the insulating film 20a, a conductive portion 25 made of a conductive material is formed. Through the conductive portion 25, the reflective electrode 11b and the source electrode 17 disposed on the lower layer side of the insulating film 20a are formed. And are electrically connected. Therefore, the source electrode 17 is electrically connected to both the transmissive electrode 11a and the reflective electrode 11b.

On the substrate 6 configured as described above, an alignment film 29 made of polyimide or the like subjected to a predetermined alignment process such as rubbing is formed so as to cover the reflector 20 and the recess 22. The alignment film 29 includes a first alignment film 29 a stacked on the entire surface of the substrate 6 and a second alignment film 29 b stacked only in the recess 22. That is, only the first alignment film 29a is stacked on the reflective electrode 11b, while the first alignment film 29a and the second alignment film 29b are sequentially stacked on the transmission electrode 11a in the recess 22. . The pretilt angle of the liquid crystal molecules by the first alignment film 29a is set larger than the pretilt angle of the liquid crystal molecules by the second alignment film 29b. That is, the pre-tilt angle of the first alignment film 29a is set in the range of 40 ° to 90 °, and the pre-tilt angle of the second alignment film 29b is set in the range of 10 ° or less.

Examples of the first alignment film 29a include those exhibiting vertical alignment among polyimide alignment films, such as SE-1211, RN1199 (manufactured by Nissan Chemical Co., Ltd.), JALS204 (manufactured by JSR), and the like.
These materials are 1 to 10% by mass (usually about 3 to 6% by mass) as a solid component concentration in a solvent (N-methylpyrrolidone or γ-butyrolactone or other highly soluble material is selected). The ink is made into an ink having a viscosity of about 10 to 40 cp, and is adjusted by spin coating or transfer printing (a technique such as gravure printing or flexographic printing is used) so that the film thickness after baking becomes 300 to 1000 mm. Is done.
Further, when these material systems are used, after printing preliminary drying, polarized or non-polarized light having a wavelength of 250 nm to 360 nm is irradiated from a direction inclined by 5 ° to 50 ° with respect to the normal direction of the substrate surface. The pretilt angle can be controlled by a method such as heating to ˜260 ° C.

In addition, although not based on polyimide, for example, a polyvinyl cinnamate (cinnamate) compound represented by [Chemical Formula 1], an oxyalkyloxybiphenyl represented by [Chemical Formula 2], and [Chemical Formula 3] An oxyalkylbiphenylacrylcinnamate compound, a methacrylate (acrylate ester) compound having an azobenzene group in the main chain represented by [Chemical Formula 4], or the like can also be used as the first alignment film 19a. Also in these compounds, treatment methods similar to those described above, that is, UV light irradiation or heat treatment can be used, and by using these in combination, the pretilt angle can be controlled between 70 ° and 89 °. In addition, in [Chemical Formula 3], it is favorable when n ₃ is 2 to 6. On the other hand, when n ₃ exceeds 10, vertical alignment is easily obtained. In [Chemical Formula 5], n ₅ is preferably 8 or more, and more preferably n ₅ = 8 or 16.

  Furthermore, although it is not a polyimide material, the trimethoxyalkylsilane compound represented by [Chemical Formula 5] or the triethoxyalkylsilane compound represented by [Chemical Formula 6] is 0 in the water-alcohol solvent injection. 5% by mass to 5% by mass is dissolved and applied to the substrate by transfer printing or spin coating, and then heated to 100 ° C. to 130 ° C. Then, the first alignment film 29a is obtained by performing a rubbing process so as to be in a direction to be inclined in the bend alignment state.

  Next, the second alignment film 29b is made of, for example, polyimide obtained by the reaction formula shown in [Chemical Formula 7] below. The polyimide shown in [Chemical Formula 7] is a soluble polyimide having an alicyclic structure, and no special side chain is introduced into the main chain. This alignment film made of polyimide can have a pretilt angle of 4 ° or less. As a specific example, an optomer series manufactured by Nippon Synthetic Rubber Co., Ltd. can be exemplified.

  Next, in the recess 22 formed in the insulating film 20a, a step portion 22c that is a side wall of the recess 22 corresponding to the thickness of the insulating film 20a is formed. In the present embodiment, the inclination angle of the step portion 22c is set in a range of 25 ° to 55 °. With this configuration, light can be reflected at the stepped portion 22c, the boundary between the transmitting portion 30 and the reflecting portion 35 is not conspicuous, and display unevenness can be prevented. In particular, it is desirable that the inclination angle of the stepped portion 22c matches the pretilt angle of the liquid crystal molecules on the second alignment film 29b. Thereby, the boundary between the transmission part 30 and the reflection part 35 is not conspicuous, and display unevenness can be prevented.

Next, the counter substrate 3 is formed with a color filter layer 42 as shown in FIG. 2 on the surface of the translucent substrate 41 made of glass, plastic or the like on the liquid crystal layer 5 side.
The color filter layer 42 has a structure in which color filters that transmit light of wavelengths of red (R), green (G), and blue (B) are periodically arranged, and each color filter has a pixel electrode. 11 (11a, 11b). In the color filter layer 42, a light shielding layer such as a black matrix is formed in a lattice shape in a region where the color filter is not formed.

  In addition, the color filter layer 42 is disposed on the reflective portion 35, the reflective color filter layer 42a, the transparent resin layer 42b laminated on the reflective color filter layer 42a, and the transmissive portion 30 for reflection. The transmission color filter layer 42c is integral with the color filter layer 42a for transmission. The thickness of the reflective color filter layer 42a is half the thickness of the transmissive color filter layer 42c. The total thickness of the reflective color filter layer 42a and the transparent resin layer 42b and the thickness of the transmissive color filter layer 42c are formed to be substantially the same thickness. Thereby, the surface of the color filter layer 42 on the liquid crystal layer 5 side is a flat surface.

  A transparent counter electrode (common electrode) 43 such as ITO and a common alignment film 44 are formed on the liquid crystal layer side of the color filter layer 42 described above. The common alignment film 44 is made of polyimide or the like that has been subjected to a predetermined alignment process such as rubbing, and is set to a pretilt angle substantially equal to the pretilt angle of the second alignment film 29b.

  The substrates 2 and 3 configured as described above are held in a state of being spaced apart from each other by a spacer (not shown) and are applied in a rectangular frame shape around the substrate as shown in FIG. The thermosetting sealing material 45 is bonded and integrated. Then, liquid crystal is sealed in a space sealed by the substrates 2 and 3 and the sealing material 45 to form a liquid crystal layer 5 as a light modulation layer, and the liquid crystal cell 1 is configured.

In the transflective liquid crystal display device A of the present embodiment, the recess 22 is formed in the insulating film 20a as described above, and liquid crystal is introduced into the recess 22 as well, so that the liquid crystal layer 5 in the transmissive portion 30 is obtained. the thickness d ₃ of is the thickness d ₄ is greater than value of the liquid crystal layer 5 in the reflective portion 35, preferably the thickness d ₃ of the liquid crystal layer 5 in the transmissive portion 30, the thickness of the liquid crystal layer 5 in the reflective portion 35 d The value is approximately twice that of ₄ . That is, the sum of the thickness of the reflector 20 and the thickness d ₄ of the liquid layer 5 in the reflecting portion 35 is equal to the thickness d ₃ of the liquid crystal layer 5 in the transmitting portion 30.

Next, the optical characteristics of the liquid crystal cell 1 will be described.
The liquid crystal layer 5 is made of liquid crystal molecules that are in a nematic state at room temperature.
In the liquid crystal layer 5 in the transmissive portion 30, as shown in FIG. 2, when a reference voltage (voltage for white display) is applied, the liquid crystal molecules in the vicinity of the common alignment film 44 and the second alignment film 29b are aligned in parallel ( The pretilt angle is 0 ° to 4 °), the liquid layer molecules in the vicinity of the center of the liquid layer 5 are vertically aligned, and the so-called bent alignment is arranged as a whole in an arcuate shape. Further, when a voltage is gradually applied from the reference voltage, the pretilt angle of the liquid crystal molecules in the vicinity of the alignment films 44 and 29a gradually increases according to the applied voltage, and hierarchical display becomes possible. As described above, in the liquid crystal display device of the present embodiment, the transmission unit 30 is configured to operate in the OCB mode.

  On the other hand, in the liquid layer 5 in the reflective portion 35, as shown in FIG. 2, when a reference voltage (voltage for white display) is applied, the liquid crystal molecules of the common alignment film 44 are aligned in parallel (the pretilt angle is 0). The liquid crystal molecules in the vicinity of the first alignment film 29a are vertically aligned (the pretilt angle is 88 ° to 90 °), and the liquid layer molecules in the vicinity of the center of the liquid layer 5 are vertically aligned. The so-called hybrid orientation is arranged in an arcuate shape. As the voltage is gradually applied from the reference voltage, the pretilt angle of the liquid crystal molecules in the vicinity of the common alignment film 44 gradually increases according to the applied voltage, and hierarchical display is possible. As described above, the liquid crystal display device of the present embodiment is configured to operate in a mode similar to the OCB mode in the reflection unit 35.

As described above in detail, according to the transflective liquid crystal display device A of the present embodiment, the pretilt angle of the first alignment film 29a is set larger than the pretilt angle of the second alignment film 29b. In the mode and the reflection mode, a good white display with high brightness and high contrast can be obtained.
Moreover, the display state in the transmission part 30 and the reflection part 35 can be made uniform, and display unevenness can be prevented. In particular, contrast unevenness can be eliminated.

Moreover, since the thickness of the color filter layer 42a in the reflection part 35 is set to one half of the thickness of the color filter layer 42c in the transmission part 30, the occurrence of color unevenness in the transmission part 30 and the reflection part 35 is prevented. Thus, the contrast can be made constant and the luminance can be increased.
In addition, since the transparent resin layer 42b in the reflection part 35 and the color filter layer 42c in the transmission part 30 form the same surface on the liquid crystal layer 5 side, the cell gap of the liquid crystal cell 1 can be easily controlled. .

Furthermore, since the thickness d ₄ of the liquid layer 5 in the reflection part 35 is set to be approximately twice the thickness d ₃ of the liquid crystal layer 5 in the transmission part 30, the light transmitted through the liquid crystal layer 5 in the reflection part 35 The optical path length and the optical path length of the light transmitted through the liquid crystal layer 5 in the transmission part 30 can be made substantially coincident.

Next, a manufacturing method of the transflective liquid crystal display device A of this embodiment will be described.
First, as shown in FIG. 3, scanning lines and signal lines, a switching element 10, and a transmission electrode 11a are formed on a substrate 6. Further, the insulating film 20a is laminated on the substrate 6, and the reflective electrode 11b is formed on the insulating film 20a. The insulating film 20a is provided with a recess 22 to expose the transmissive electrode 11a. The thickness of the insulating film 20a is preferably about 2 μm.

Next, as shown in FIG. 4, a first alignment film 29a is formed on the entire surface of the substrate 6, that is, on the reflective electrode 11b and the transmissive electrode 11a. In order to form the first alignment film, first, a solution in which the compound having the structure shown in the above [Chemical Formula 1] to [Chemical Formula 7] is dissolved is prepared. This solution is obtained by dissolving the polyimide represented by [Chemical Formula 1] or [Chemical Formula 7] in a solvent of either N-methylpyrrolidone or γ-butyrolactone to be varnished.
Then, this solution is uniformly applied to the entire surface of the substrate 6 by spin coating, flexographic printing, spin coating, or the like. After coating, a coating film is formed by heat treatment to volatilize the solvent. And the 1st orientation film 29b is formed by giving a rubbing process to the coating film after formation. The first alignment film 29a is preferably formed to a thickness of about 400 to 1000 after firing.

The manufacturing method of the first alignment film 29a will be described in more detail.
First, the case of using a vertical alignment film material having a long-chain alkyl group (SE-1211 manufactured by Nissan Chemical Co., Ltd.) as the material of the alignment film 29a will be described. First, SE-1211 is dissolved in a solvent composed of N-methylpyrrolidone to prepare a 5 mass% solution. Next, this solution is applied to the entire surface of the substrate 6 by spin coating or transfer printing. After coating, heat at 190 ° C. for 20 minutes. Thereby, a coating film having a film thickness of about 600 mm or less is obtained. Rubbing against the resulting coating film, an oblique direction of 45 ° of the coating film surface, wavelength 250nm or less, the irradiation dose 0.5 J / cm ² or less (more preferably 0.1 J / cm ² or more 0.5 J / cm ² The following is performed by irradiating with UV light.

Next, a case where the compound described in [Chemical Formula 1] is used as the material of the first alignment film 29a will be described. First, the compound shown in the above [Chemical Formula 1] is dissolved in a solvent composed of methylene chloride or acetone to prepare a 20 mass% solution. Next, this solution is applied to the entire surface of the substrate 6 to a thickness of about 400 nm or less by spin coating or transfer printing. After application, heat at 85 ° C. for 40 seconds. Thereby, a coating film is obtained. The rubbing treatment on the obtained coating film is performed by irradiating the coating film surface with polarized UV light having a wavelength of 254 nm and an intensity of about 1.0 mW / cm ^{2 for} about 40 minutes. The UV light is irradiated by, for example, an ultrahigh pressure mercury lamp (for example, USH-250D type manufactured by USHIO). In this way, the pretilt angle is set in the range of 30 ° to 40 °.

Next, the case where the compound described in [Chemical Formula 2] is used as the material of the first alignment film 29a will be described. First, the compound shown in the above [Chemical Formula 2] is dissolved in a solvent composed of methylene chloride or acetone to prepare a 1.5 mass% solution. Next, this solution is applied to the entire surface of the substrate 6 to a thickness of about 500 mm or less by spin coating or transfer printing. After coating, heat at 85 ° C. for 20 seconds. Thereby, a coating film is obtained. The obtained coating film is rubbed at room temperature from a 30 ° to 60 ° oblique direction of the coating surface with unpolarized UV light having a wavelength of 365 nm and an intensity of 1.0 mW / cm ² or less for about 4 seconds to 12 seconds. This is done by irradiation. The UV light is irradiated by, for example, an Hg-Xe lamp. In this way, the pretilt angle is set in the range of 60 ° to 85 °. When the UV light irradiation time exceeds 10 seconds, the pretilt angle decreases to 20 ° at the minimum. For example, when the irradiation time of UV light is 13 seconds, the pretilt angle is 45 °.

Next, the case where the compound described in [Chemical Formula 3] is used as the material of the first alignment film 29a will be described. First, the compound shown in the above [Chemical Formula 3] is dissolved in a solvent composed of methylene chloride or acetone to prepare a solution. Next, this solution is applied to the entire surface of the substrate 6 to a thickness of about 800 mm or less by spin coating or transfer printing. After the application, irradiation with polarized UV light is performed with an ultrahigh pressure mercury lamp at room temperature to 50 ° C. The UV light preferably has a wavelength of 300 nm and an intensity of 10 J / cm ² or less. In this way, the first alignment film 29a having a pretilt angle in the range of 85 ° to 89 ° is formed.

Next, the case where the compound described in [Chemical Formula 4] is used as the material of the first alignment film 29a will be described. First, the compound shown in the above [Chemical Formula 4] is dissolved in a solvent composed of methylene chloride or acetone to prepare a solution. Next, this solution is applied to the entire surface of the substrate 6 to a thickness of about 400 mm or less by spin coating or transfer printing. Non-polarized UV light having a wavelength of 365 nm and an intensity of 15 J / cm ² or less is irradiated by an Hg-Xe lamp from an angle of 60 ° or less with respect to the substrate surface. After irradiation, heat treatment is performed at 100 ° C. for 30 minutes. In this way, the first alignment film 29a having a pretilt angle in the range of 70 ° to 85 ° is formed. In the case where UV light is not irradiated, the pretilt angle is about 80 °.

  Next, the case where the compound described in the above [Chemical Formula 5] or [Chemical Formula 6] is used as the material of the first alignment film 29a will be described. First, the compound shown in the above [Chemical Formula 5] or [Chemical Formula 6] is dissolved in a water-ethanol mixed solvent (ethanol 5% or less) to prepare a 0.5 to 5 mass% solution. Next, this solution is applied to the entire surface of the substrate 6 by a transfer printing method. After coating, the substrate is heated to 120 ° C. to remove the solvent. Then, a normal method rubbing process is performed. Thereby, the first alignment film 29a is formed.

Next, as shown in FIG. 5, an inkjet nozzle N is disposed on the recess 22 on the substrate 6, that is, the transmission electrode 11 a, and the solution L containing the constituent material of the second alignment film is discharged from the nozzle N. . This solution L is obtained by dissolving the polyimide having the structure shown in the above [Chemical Formula 3] in γ-butyrolactone to be varnished. By discharging the solution L from the inkjet nozzle N, it is possible to accurately land the droplet of the solution L on the transmission electrode 11a. In addition, since the insulating film 20a is removed and the recess 22 is formed around the transmission electrode 11a, the solution L does not overflow to the outside of the recess 22.
As shown in FIG. 6, the discharged solution L becomes a polyimide film having a structure shown in [Chemical Formula 3] by volatilizing γ-butyrolactone as a solvent. The laminated polyimide film is rubbed to form a second alignment film 29b. In this manner, the second alignment film 29b is stacked on the first alignment film 29a on the transmission electrode 11a. The second alignment film 29b is desirably formed to a thickness of about 400 to 1000 mm after firing. As described above, the active matrix substrate 2 formed with the first and second alignment films 29a and 29b is obtained.

The first alignment film 29a serves as a solution receiving layer when the solution L is discharged by the inkjet nozzle N. That is, when the solution L lands in the concave portion 22, the solution L becomes familiar with the first alignment film 29a, and the solution L spreads uniformly and the second alignment film 29b having a constant film thickness is formed. The reason why the solution L and the first alignment film 29a are easily adapted is that the material constituting the first alignment film 29a is the polyimide described above, and this polyimide has high affinity with γ-butyrolactone, which is the solvent of the solution L.
Since the recess shape is a solution-receiving layer in this way, when forming the shape of the pattern corresponding to the transmissive part, if the ejection amount during ink jet printing is controlled, the position accuracy with respect to the formation pattern position and shape The tolerance for is widened. As a solution receiving layer, a polyvinyl alcohol layer or the like may be formed on the first alignment film 29a in the recess 22 in advance.

  Next, a common substrate in which a color filter layer, a common electrode, and a common alignment film are formed is prepared, and this common substrate and the previously produced active matrix substrate are bonded to each other with a certain distance therebetween. The liquid crystal panel 1 shown in FIG. 2 is obtained by encapsulating the liquid crystal layer.

  As described above, the manufacturing method of the liquid crystal display device according to the present embodiment employs a so-called inkjet method in which the solution L is discharged onto the first alignment film 29a to form the second alignment film 29b. In this method, the second alignment film 29b is formed by evaporating only the volatile solvent after discharging the solution L. As a result, there is no problem of liquid residue and spot generation as in the conventional method, and alkali residue does not occur. In addition, the formation position of the second alignment film 29b can be precisely controlled by using the ink jet method.

  As a result, when the regions having different pretilt angles are selectively formed, the alignment films 29a and 29b can be formed in a non-contact manner quickly and with a required pattern accuracy. In particular, when the transmissive electrode 11a serving as a transmissive portion is formed as a concave portion 22 that can easily receive a solution, the first alignment film 29a formed in advance functions as a solution receiving layer, so that the second alignment film 29b The flatness and pattern accuracy are significantly improved, and pinholes can be prevented from occurring. Further, since an alkaline etchant is not used, residual alkali can be reduced, and voltage holding characteristics of the liquid crystal layer can be improved.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above embodiment, the first alignment film is formed on the entire surface of the substrate 6 and then the second alignment film is formed on the transmission part 30 by the ink jet method. Instead, the first alignment film is formed on the entire surface of the substrate. Then, the second alignment film may be formed on the reflective portion by an ink jet method. In this case, it is desirable to make the pretilt angle of the first alignment film smaller than the pretilt angle of the second alignment film. For this purpose, the constituent materials of the first and second alignment films 29a and 29b in the above embodiment may be replaced.

  Further, the number of inkjet nozzles is not limited to one, and it is of course possible to form a second alignment film by simultaneously discharging solutions from a plurality of inkjet nozzles into a plurality of recesses. In this case, the alignment film can be formed quickly.

FIG. 1 is a schematic cross-sectional view showing an example of a liquid crystal display device according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing a main part of a liquid crystal display device according to an embodiment of the present invention. FIG. 3 is a process diagram showing an example of a method for manufacturing a liquid crystal display device according to an embodiment of the present invention. FIG. 4 is a process diagram showing an example of a method for manufacturing a liquid crystal display device according to an embodiment of the present invention. FIG. 5 is a process diagram showing an example of a method for manufacturing a liquid crystal display device according to an embodiment of the present invention. FIG. 6 is a process diagram showing an example of a method for manufacturing a liquid crystal display device according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 5 ... Liquid crystal layer, 6 ... The other board | substrate, 10 ... Switching element, 11 ... Pixel electrode, 11a ... Reflection type electrode, 11b ... Transmission type electrode, 20a ... Insulating film (convex part), 22 ... Concave part, 29a ... 1st Alignment film, 29b ... second alignment film, 41 ... one substrate, 43 ... common electrode, 44 ... common alignment film, A ... liquid crystal display device, L ... solution

Claims (4)

A liquid crystal layer and a pair of transparent substrates facing each other with the liquid crystal layer interposed therebetween, and a common electrode and a common alignment film are sequentially laminated on the inner surface side of one of the transparent substrates, and the other transparent substrate A plurality of switching elements and a plurality of pixel electrodes respectively connected to the switching elements are provided on the inner surface side of the reflective electrode, the pixel electrodes reflecting light incident from the one substrate side; A method of manufacturing a liquid crystal display device comprising a transmissive electrode that transmits light from the other substrate side to the one substrate side;
Forming a first alignment film on the entire surface of the pixel electrode;
By discharging a solution containing the constituent material of the second alignment film onto the first alignment film of either the transmissive electrode or the reflective electrode, the second tilt angle is different from that of the first alignment film. And a step of forming an alignment film. A method for manufacturing a liquid crystal display device.   2. The liquid crystal display according to claim 1, wherein the second alignment film is formed on the transmission electrode, and a pretilt angle of the first alignment film is set larger than a pretilt angle of the second alignment film. Device manufacturing method.   2. The liquid crystal display according to claim 1, wherein the second alignment film is formed on the reflective electrode, and a pretilt angle of the first alignment film is set smaller than a pretilt angle of the second alignment film. Device manufacturing method. The reflective electrode is formed on a convex portion provided on the other substrate, and the transmissive electrode is formed in a concave portion corresponding to the convex portion. Item 4. A method for manufacturing a liquid crystal display device according to Item 3.

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