JP2009109689A - Semi-transmissive liquid crystal display and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify a formation process of a retardation layer, in a liquid crystal display panel which constitutes a semi-transmissive liquid crystal display, with a built-in the retardation layer. <P>SOLUTION: By using a retardation material containing a thermal polymerization initiator generating polymerization initiating species by heating, polymerization is started by thermal energy, while making the orientation properties of liquid crystal molecules to disappear by heating, to form a transparent layer which does not have retardation functions. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device, and more particularly, to a transflective liquid crystal display device including a retardation layer and a manufacturing method thereof.

  Currently, transmissive liquid crystal display devices with a wide viewing angle such as IPS (In Plane Switching) and VA (Vertical Alignment) are widely used as monitors for various devices, and are used as TVs with improved response characteristics. Yes. On the other hand, liquid crystal display devices are widely used in portable information devices such as mobile phones and digital cameras. Recently, the number of portable information devices with a variable display portion has been increasing, and a wide viewing angle is desired because observation is often performed from an oblique direction.

  A display device for a portable information device is required to be a transflective type because it is used in various environments including outdoors from a sunny day to a dark room. A transflective liquid crystal display device has a reflective display portion and a transmissive display portion in one pixel. The reflective display unit reflects and displays light incident from the surroundings using a reflector, and the contrast ratio is constant regardless of the ambient brightness, so it is a relatively bright environment from outdoor to indoors in fine weather. Good display is obtained below. On the other hand, the transmissive display unit is displayed using a backlight and has a constant luminance regardless of the environment, so that a display with a high contrast ratio can be obtained in a relatively dark environment from indoors to a dark room. A transflective liquid crystal display device having both of these characteristics can display with a high contrast ratio in a wide range of environments including outdoors from a sunny day to a dark room.

  Conventionally, it has been expected that a reflective display and a transmissive display with a wide viewing angle can be obtained at the same time if the IPS liquid crystal display device known for transmissive display with a wide viewing angle is made to be a transflective type. For example, Patent Document 1 describes a transflective IPS liquid crystal display device. In the transflective IPS type liquid crystal display device, retardation plates are arranged on the entire upper and lower outer surfaces of a liquid crystal panel in which a liquid crystal layer is sealed between two transparent substrates. This retardation plate has viewing angle dependency. Therefore, even if the phase difference between the liquid crystal layer and the plurality of retardation plates is optimized in the normal direction of the liquid crystal layer, it rapidly deviates from the optimum condition for dark display as the distance from the normal direction is increased.

  Non-Patent Document 1 discloses an installation structure and display characteristics when a retardation plate (retardation layer) is built in a liquid crystal panel instead of an externally installed retardation plate. Japanese Patent Application Laid-Open No. 2004-228688 discloses a consideration for making a transflective IPS system having a built-in retardation layer a wide viewing angle equivalent to a totally transmissive IPS system.

Since the built-in retardation layer is composed of a liquid crystal polymer, the orientation of the molecules is higher than that of a conventional external retardation plate made by stretching an organic polymer film, and Δn of the retardation layer is externally attached. It is much larger than the retardation plate. For this reason, if an external retardation plate having a layer thickness of several tens of μm is used as a built-in retardation layer using a liquid crystal polymer, the layer thickness can be greatly reduced to several μm.
Japanese Patent Laid-Open No. 11-242226 JP 2005-338256 A c. Doornkamp et al., Philips Research, “Next generation mobile LCDs with in-cell retarders.” International Display Workshops 2003, p685 (2003)

  As methods for forming a retardation layer of a liquid crystal panel constituting a transflective liquid crystal display device, there are mainly methods disclosed in Patent Document 2 and Non-Patent Document 1. FIG. 8 is a schematic cross-sectional view of the first substrate (color filter substrate) of the liquid crystal display device disclosed in Patent Document 2. FIG. 9 is a flowchart for explaining a manufacturing process of the first substrate shown in FIG. The first substrate disclosed in Patent Document 2 includes a color filter 45, a planarizing layer 36, a retardation layer alignment film 37, and a color filter 45 partitioned by a black matrix 35 on a main surface of a transparent substrate 31 preferably made of glass. The phase difference layer 38 is formed. The retardation layer forming process includes steps from process 4 (hereinafter referred to as P-4) to P-8 in FIG.

  First, a liquid crystal monomer and a photopolymerization initiator dissolved in an organic solvent are applied on the alignment layer 37 for retardation layer (P-4), pre-baked and evaporated (P-5), and then mask exposed. Then, only a necessary part is cured to form a transparent film (retardation layer) in which liquid crystal molecules are aligned by the alignment film (P-6). Further, organic development is performed to dissolve the uncured portion (P-7), and baking is performed to evaporate the residual solvent (P-8).

  FIG. 10 is a schematic cross-sectional view of the first substrate (color filter substrate) of the liquid crystal display device disclosed in Non-Patent Document 1. FIG. 11 is a flowchart illustrating a manufacturing process of the first substrate shown in FIG. The structure of Non-Patent Document 1 eliminates the color filter 45, the flattening layer 36, the retardation layer alignment film 37, the retardation layer 38, or the retardation function partitioned by the black matrix 35 on the main surface of the substrate 31. A transparent layer 100. The retardation layer forming step includes steps P-4 to P-6 and P-20 in FIG.

  First, a liquid crystal monomer and a photopolymerization initiator dissolved in an organic solvent are applied (P-4), pre-baked and evaporated (P-5), exposed to a mask, and only necessary portions are cured. A transparent film (retardation layer) in which molecules are aligned by the alignment film is formed (P-6). Furthermore, the liquid crystal molecules are heated to a temperature higher than the liquid crystal phase-isotropic phase transition temperature, and the entire surface is exposed in a state where the liquid crystal monomer in the uncured portion is in the isotropic phase, the uncured portion is cured, and the retardation function is lost. A transparent layer is formed (P-20).

  In the disclosed manufacturing method, the steps as described above are necessary for forming the retardation layer. An object of the present invention is to provide a transflective liquid crystal display device in which a retardation layer forming process is simplified by improving a retardation material.

  A typical example of the means of the present invention for solving the above problems will be described as follows. Of course, the present invention is not limited to the means described herein.

  The transflective liquid crystal display device of the present invention includes a light shielding pattern, a retardation alignment film formed on the light shielding pattern, a transparent organic film formed on the retardation film, and the transparent organic film. A first substrate having an insulating film formed thereon formed on a main surface, a thin film transistor, a second substrate having a pixel electrode driven by the thin film transistor formed on the main surface, and the first substrate And a liquid crystal layer sandwiched through a liquid crystal alignment film.

  In the present invention, the transparent organic film is a liquid crystal molecule, and the liquid crystal molecule is divided into a first region where the liquid crystal molecules are aligned by the retardation film and a second region where the liquid crystal molecules are not aligned by the retardation film. ing. The transparent organic film contains at least one compound or decomposition product of an iodonium salt, a sulfonium salt, and a peroxide, and the concentration thereof is 0.05% by weight to ensure curability with respect to the transparent organic film. In order to maintain the film quality such as the surface state and transparency of the transparent organic film, the upper limit is preferably 15% by weight.

  Moreover, when the said transparent organic film | membrane contains the compound or decomposition product of an iodonium salt or a sulfonium salt, the element of iodine and a fluorine or sulfur and a fluorine will be contained in a transparent organic film | membrane. Considering the molecular weight of this compound, the transparent organic film preferably contains the fluorine at a concentration of 250 ppm or more and 16000 ppm or less according to the concentration definition. The transparent organic film preferably contains the iodine at a concentration of 250 ppm to 30000 ppm. The transparent organic film preferably contains the above sulfur element at a concentration of 150 ppm or more and 20000 ppm or less.

  A typical example of the manufacturing method of the transflective liquid crystal display device of the present invention is as follows. That is, a light shielding pattern is formed on the first substrate, and a phase difference alignment film is formed on the light shielding pattern. A liquid film containing a liquid crystal molecule having a reactive site and a photopolymerization initiator that generates a polymerization initiating species by irradiation with ultraviolet light and a polymerization initiating species by heating on the alignment film for retardation, or A liquid film containing liquid crystal molecules having a reactive site and a thermal polymerization initiator that generates a polymerization initiating species by both ultraviolet light irradiation and heating is formed.

  The liquid film is selectively irradiated with ultraviolet light to form a transparent film (retardation layer) in which liquid crystal molecules are aligned by the alignment film for retardation film. Thereafter, the substrate is heated to a temperature higher than the liquid crystal phase-isotropic phase transition temperature of the liquid crystalline monomer and the polymerization initiator generates a polymerization initiating species at a concentration at which polymerization is initiated by heat, and the liquid film of the ineffective portion Is cured to form a transparent film in which liquid crystal molecules are not aligned by the alignment film. An insulating film is formed on this transparent film.

  The present invention improves the characteristics of the retardation layer in the transflective liquid crystal display device incorporating the retardation layer, regardless of the liquid crystal driving method such as the IPS method and the VA method, simplifies the formation process, The environmental burden associated with manufacturing is reduced.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS The best mode for carrying out the present invention will be described below in detail with reference to the drawings of the examples.

  FIG. 1 is a plan view illustrating a schematic configuration example of one pixel of a liquid crystal panel included in a liquid crystal display device according to the present invention. FIG. 2 is a cross-sectional view taken along the line A-A ′ of FIG. 1 for explaining a schematic configuration example of one pixel of the liquid crystal panel shown in FIG. 1. The liquid crystal panel of this embodiment is composed of a first substrate 31, a liquid crystal layer 10, and a second substrate 32, and the liquid crystal layer 10 is disposed in the opposing gaps between the main surfaces of the first substrate 31 and the second substrate 32. Be held.

  On the main surface (inner surface) of the first substrate 31, a color filter 45, a flattening layer (first protective film) 36, a retardation layer alignment film 37, and a retardation layer 38 or a layer partitioned by a black matrix 35. The transparent layer 100 in which the phase difference function is lost, the protective layer (second protective film) 40 of the phase difference layer, and the first liquid crystal alignment film 33 are sequentially stacked.

  The alignment layer 37 for retardation layer is provided with an alignment control ability for controlling the alignment of the forming material of the retardation layer 38 made of the liquid crystal layer composition. The first liquid crystal alignment film 33 is provided with an alignment control ability for controlling the initial alignment of the liquid crystal layer 10 for controlling display light.

  The main surface of the second substrate 32 has a thin film transistor TFT for driving a pixel. The thin film transistor TFT is connected to the scanning wiring 21, the signal wiring 22, and the pixel electrode 28. In addition, a common wiring 23 and a common electrode 29 are provided. Here, the thin film transistor TFT has an inverted staggered structure, and its channel portion is formed of an amorphous silicon (a-Si) layer 25. The scanning wiring 21 and the signal wiring 22 intersect with each other in the row direction and the column direction to form a two-dimensional matrix, and the thin film transistor TFT is roughly located near the intersection. A part of the scanning wiring 23 extends below the amorphous silicon layer 25 and is separated from the amorphous silicon layer 25 by the first insulating layer 51. A part of the scanning wiring 23 is also called a gate electrode, and an electric field is applied to the amorphous silicon layer 25 through the first insulating layer (gate insulating film) 51 to control a current flowing through the amorphous silicon layer 25. The first insulating layer is formed as an oxide film or a nitride film of a semiconductor material (silicon in this embodiment) forming a channel.

  The common wiring 23 is arranged in parallel with the scanning wiring 21 and is connected to the common electrode 23 through the second through hole 27. The pixel electrode 28 and the source / drain electrode 24 of the thin film transistor TFT are coupled by a first through hole 26 formed through the second insulating layer 52 covering the thin film transistor TFT. The second insulating layer 52 is formed of an inorganic insulating material such as the oxide or nitride of the semiconductor material described above, or an organic insulating material such as a resin. A second liquid crystal alignment film 34 is provided on the pixel electrode 28 and has an alignment control ability for controlling the initial alignment of the liquid crystal layer 10.

  The first substrate 31 in the present embodiment is preferably made of borosilicate glass with few ionic impurities and has a thickness of 0.5 mm, for example. The color filter 45 partitioned by the black matrix 35 has red, green, and blue portions (color subpixels) arranged repeatedly in a stripe pattern, and each stripe is parallel to the signal electrode 22. The unevenness of the formation surface of the black matrix 35 and the color filter 45 is flattened by a resinous flattening layer (first protective film, overcoat film) 36. The first liquid crystal alignment film 33 is a polyimide polymer film, and is subjected to alignment treatment by a rubbing method.

  The second substrate 32 is suitably borosilicate glass similar to the first substrate 31 and has a thickness of 0.5 mm, for example. Similarly to the first liquid crystal alignment film 33, the second liquid crystal alignment film 34 is a horizontal alignment polyimide polymer film. The signal wiring 22, the scanning wiring 21, and the common wiring 23 are formed of aluminum (Al), an alloy thereof (alloy of aluminum and neodymium: Al—Nd), chromium (Cr), or the like, and the pixel electrode 28 is formed of indium. A transparent conductive film such as tin oxide (indium tin oxide: ITO) is desirable, and the common electrode 29 is also desirably formed of a transparent conductive film such as ITO.

  The pixel electrode 28 has slits 30 parallel to the scanning wiring 21 and the pitch of the slits 30 is about 4 μm. The pixel electrode 28 and the common electrode 29 are separated by a third insulating layer 53 having a layer thickness of 0.5 μm, and an electric field is formed between the pixel electrode 28 and the common electrode 29 when a voltage is applied. Due to the influence of the insulating layer 53, the electric field is distorted in an arch shape and passes through the liquid crystal layer 10. As a result, an orientation change occurs in the liquid crystal layer 10 when a voltage is applied. The above numerical values are merely examples including other numerical values in the present specification and drawings, and the present invention is not limited to these numerical values. Similarly to the second insulating layer 52, the third insulating layer 53 is also formed of an inorganic or organic insulating material. The first to third insulating layers 51 to 53 are also called interlayer insulating films.

  The common wiring 23 has a structure projecting into the pixel electrode 28 at a portion intersecting with the pixel electrode 28. In FIG. 1, the portion where the common wiring 23 overlaps with the pixel electrode 28 is a reflective display portion, and the other portion where the pixel electrode 28 and common electrode 29 overlap is a transmissive display portion through the backlight. . In FIG. 2, the outer main surface of the first substrate 31 enters the liquid crystal panel from the outer main surface (the second polarizing plate 42 is disposed) of the second substrate 32, passes through the liquid crystal layer 10, and The optical path of “transmitted light 61” emitted from the liquid crystal panel (from which the first polarizing plate 41 is disposed) and the liquid crystal panel 10 are incident on the liquid crystal panel from the outer main surface of the first substrate 31. The light is reflected and reflected by a portion (so-called reflective layer) that extends below the pixel electrode 28 of the common wiring 23 and passes through the liquid crystal layer 10 again, and from the outer main surface of the first substrate 31 to the outside of the liquid crystal panel. The optical paths of the emitted “reflected light 62” are illustrated by arrows. Since the optimum layer thickness of the liquid crystal layer is different between the transmissive display portion and the reflective display portion, a step is generated at the boundary. In order to shorten the boundary between the transmissive display unit and the reflective display unit, the transmissive display unit and the reflective display unit are arranged so that the boundary is parallel to the short side of the pixel.

  Thus, if the wiring such as the common wiring 23 is also used as a reflector, an effect of reducing the manufacturing process can be obtained. If the common wiring 23 is made of aluminum having a high reflectance, a brighter reflective display can be obtained. The same effect can be obtained even if the common wiring 23 is made of chromium and a reflector made of aluminum or silver alloy is separately formed.

  The liquid crystal layer 10 is a liquid crystal layer composition exhibiting positive dielectric anisotropy in which the dielectric constant in the alignment direction is larger than that in the normal direction. Here, the birefringence is 0.067 at 25 ° C., and a nematic phase is exhibited in a wide temperature range including a room temperature region. In addition, during a holding period when driving at a frequency of 60 Hz using a thin film transistor, a high resistance value that does not cause flicker by sufficiently holding reflectance and transmittance is exhibited.

  FIG. 3 is an explanatory diagram of the manufacturing process of the liquid crystal panel constituting the liquid crystal display device according to the first embodiment of the present invention. The manufacturing process of FIG. 3 will be described with reference to the structure of the liquid crystal panel shown in FIG.

  The black matrix 35 and the color filter 45 are formed on the main surface of the first substrate 31, and the surface is covered with the first protective film 36 and planarized (P-1).

  Next, an alignment film 37 for retardation layer is applied (P-2).

  Next, the alignment layer 37 for retardation layer is baked and then rubbed to impart alignment control ability (P-3). Here, rubbing is used in order to provide alignment control ability, but the liquid crystal monomer to be applied next may be aligned, such as a photo alignment film, an ion beam alignment film, and a stretched film, instead of rubbing.

  The retardation layer alignment film 37 is horizontally oriented and has a function of determining the slow axis direction of the retardation layer 38. A polymerization inhibitor that controls the degree of polymerization by dissolving a nematic liquid crystal monomer having a reactive functional group at the molecular end, a photopolymerization initiator, and a thermal polymerization initiator in an organic solvent on the alignment layer 37 for retardation layer. And a phase difference material to which a leveling agent for improving applicability is added is applied (P-4).

Examples of nematic liquid crystal monomers having an acrylic group (acrylate) at the molecular end as a reactive functional group are shown in “Chemical Formula 1” and “Chemical Formula 2”. Note that the reactive functional group is not an acrylic group, but may be an epoxy group, as long as a polymerization reaction occurs.

  Further, as photopolymerization initiators, IRGACURE 651, IRGACURE 184, DAROCUR 1173, IRGACURE 500, IRGACURE 2959, IRGACURE 127, IRGACURE IR, IRGACURE IR, IRGACURE IR, IRGACURE IR IRGACURE 4265, DAROCUR TPO, IRGACURE 819, IRGACURE 819DW, IRGACURE 784, IRGACURE OX 01, IRGACURE OXE 02, IRGACURE 754, and the like.

  Examples of the organic solvent for the retardation material include propylene glycol monomethyl ether acetate, cyclohexanone, ethylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, methoxybutyl acetate, diethylene glycol dimethyl ether, and diethylene glycol methyl ethyl ether. be able to.

Moreover, there are mainly types of thermal polymerization initiators that generate radicals by heating and those that generate cations by heating. Examples of the thermal polymerization initiator that generates radicals by heating include peroxide compounds. An example is shown in “Chemical Formula 3”. (R1 to R4 represent a substituent selected from a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an aryl group, a heteroaryl group, and the like, and n represents an integer of 1 to 10.)

In addition, as thermal polymerization initiators that generate cations by heating, there are compounds of sulfonium salts and iodonium salts. Examples are shown in “Chemical 4” and “Chemical 5”, respectively. R1 to R3 represent a substituent selected from a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an aryl group, a heteroaryl group, and the like.

  After applying the phase difference material, it is pre-baked for 3 minutes with a hot plate at 70 ° C. to remove the solvent, thereby forming a transparent liquid film (P-5). This liquid film is oriented in the orientation treatment direction of the retardation film orientation film 37 even in an uncured state.

  The liquid film is selectively irradiated with ultraviolet light using an exposure mask having an opening, and a transparent film (retardation layer) 38 in which liquid crystal molecules are aligned is formed by the alignment film. (P-6). At this time, by irradiating the photopolymerization initiator with ultraviolet light, a polymerization initiating species is generated, the nematic liquid crystal monomer is polymerized and retained while maintaining the alignment, and the liquid crystal molecules are aligned by the alignment film. It becomes a transparent film. On the other hand, the unexposed part maintains the orientation by the orientation control ability of the orientation film and is in an uncured liquid film state. In addition, the film concentration is adjusted by appropriately adjusting the solution concentration and the coating conditions during coating so that the retardation of the retardation layer 38 becomes a half wavelength at a wavelength of 550 nm.

Then, it heats to 140 degreeC or more, the liquid film which was not exposed is hardened, and the transparent film with which the liquid crystal molecule is not oriented is formed (P- 30 ). Since the heating temperature at this time is higher than the liquid crystal phase-isotropic phase transition temperature of the nematic liquid crystal monomer, the liquid crystal monomer exists in a random orientation without being aligned. At this time, since the heating temperature is equal to or higher than the polymerization start temperature of the thermal polymerization initiator added to the retardation material, a polymerization reaction of the liquid crystal monomer occurs. As a result, the liquid crystal monomer is cured in a random state, so that a transparent film having no phase difference is formed. In addition, when using the polymerization initiator which generate | occur | produces a radical, the reactivity raises by performing on the conditions which are hard to receive oxygen inhibition, such as heating by nitrogen atmosphere.

  The conditions required for the thermal polymerization initiator are that the polymerization reaction does not start below the liquid crystal phase-isotropic phase transition temperature of the liquid crystal monomer, and the concentration required for the polymerization reaction at a temperature above the liquid crystal phase-isotropic phase transition temperature. It is necessary to generate a polymerization initiating species. In addition, since the liquid crystal monomer is decomposed when the temperature is too high, curing must be started at a temperature lower than the decomposition temperature of the liquid crystal monomer.

  Here, the half-life of the thermal polymerization initiator will be described with reference to FIG. FIG. 4 is a schematic diagram for explaining the half-life of the polymerization initiator. The thermal polymerization initiator causes a reaction to generate a polymerization initiating species by thermal energy. Even if the thermal polymerization initiator has a high activation energy, it reacts little by little at room temperature. Therefore, the reactivity of the polymerization initiator is expressed as a half-life. The half-life is the time until half of the molecules react with the initial number of molecules. For example, the half-life of the molecule indicated by the line A in FIG. 4 is 10 minutes, and the half-life of the molecule indicated by the line B is 60 minutes. The number of polymerization initiating species generated by heating is determined by the temperature, half-life and concentration of the polymerization initiator.

  In this example, in order to avoid the polymerization reaction starting in the step (P-5) of heating with a hot plate at 70 ° C., the half-life of the thermal polymerization initiator at 70 ° C. should be 10 minutes or more. desirable. Moreover, since liquid crystal molecules are decomposed when the temperature is too high, it is desirable that the half-life of the thermal polymerization initiator at 230 ° C. is within 1 hour.

  Any thermal polymerization initiator satisfying the above conditions can be used other than those represented by “Chemical Formula 3”, “Chemical Formula 4”, and “Chemical Formula 5”.

  In this way, it is possible to react the uncured portion only by heating to form a transparent film having no retardation function, so that organic development is performed as in known examples, or the entire surface is exposed. This is not necessary, and can be performed with a simple apparatus configuration and with a simple process.

  Again, with reference to FIG.2 and FIG.3, the manufacturing process of a liquid crystal panel is demonstrated. A transparent organic layer is applied on the retardation layer 38 to form the second protective layer 40 (P-9). The protective layer 40 also serves as a barrier layer that blocks decomposition products during the polymerization reaction of the retardation layer.

  If the retardation layer 38 has a Δn larger than twice that of the liquid crystal layer, the thickness of the retardation layer 38 becomes insufficient when the retardation is set to a half wavelength, and only the retardation layer 38 is used. Then, the retardation difference between the reflective display portion and the transmissive display portion is smaller than a quarter wavelength. Therefore, in order to secure a quarter-wave retardation difference between the reflective display portion and the transmissive display portion, a film thickness adjusting layer 39 is then formed on the retardation layer 38. A photosensitive transparent resist is applied to the second protective layer 40, and ultraviolet light is selectively irradiated using an exposure mask. Here, patterning is performed using an exposure mask having a distribution similar to that of the reflective display portion. Thereafter, the film thickness adjusting layer 39 is formed only on the upper layer of the retardation layer 38 by alkali development (P-10). Further, a columnar spacer for maintaining the gap of the liquid crystal layer is formed thereon (P-11).

  The first liquid crystal alignment film 33 is applied to the uppermost layer of the main surface of the first substrate 31, and the second liquid crystal alignment film 34 is applied to the uppermost layer of the main surface of the second substrate 32, and a rubbing process (P -12), columnar spacers are interposed in the display areas of the first substrate 31 and the second substrate 32, a sealing material is applied to the inside of the outer peripheral edge, the two substrates are bonded together, and assembled, and the liquid crystal layer on the inside 10 is enclosed (P-13).

  Finally, the first polarizing plate 41 and the second polarizing plate 42 are disposed outside the first substrate 31 and the second substrate 32, respectively. The transmission axes of the first polarizing plate 41 and the second polarizing plate 42 are arranged so as to be orthogonal and parallel to the alignment direction of the liquid crystal layer (P-14).

  In this embodiment, the light diffusive pressure-sensitive adhesive layer 43 in which a large number of transparent microspheres having a refractive index different from that of the pressure-sensitive adhesive material is mixed is used for the pressure-sensitive adhesive layer 43 of the first polarizing plate 41. With such a configuration, the optical path of incident light is expanded by utilizing the effect of refraction caused by the difference in refractive index between the adhesive material and the microsphere. Thereby, it is possible to reduce iridescent coloring caused by interference of reflected light between the pixel electrode 28 and the common electrode 29. However, the configuration of the adhesive layer 43 is not limited to this, and it goes without saying that an adhesive material without microspheres may be used.

  In the transmissive display portion of the transflective liquid crystal panel of the present example produced as described above, the transmission axis of the first polarizing plate 41 and the transmission axis of the second polarizing plate 42 are orthogonal, and the latter is the liquid crystal alignment. Parallel to the direction. Since this is the same configuration as that of the transmissive IPS system, a wide viewing angle that can withstand monitor applications can be obtained for transmissive display as in the transmissive IPS system.

  In the present embodiment, the panel structure and manufacturing process of the IPS type built-in phase difference type transflective liquid crystal panel have been described. However, the present invention also applies to the VA type and other liquid crystal drive type built-in phase difference type transflective liquid crystal panels. The invention can be used. In this case, the TFT structure, color filter pixel structure, retardation layer retardation value, and other panel configurations may differ depending on the liquid crystal drive method. However, by adding an appropriate thermal polymerization initiator to the retardation material. The process of the present invention can be carried out and the effect is exhibited.

  The configuration of the transflective liquid crystal display device according to the second embodiment of the present invention is the same as that shown in FIGS. 1 and 2 for explaining the first embodiment. The flow of the manufacturing process of Example 2 will be described with reference to FIG.

  The black matrix 35 and the color filter 45 are formed on the main surface of the first substrate 31, and the surface is covered with the first protective film 36 and planarized (P-1).

  Next, an alignment film 37 for retardation layer is applied (P-2).

  Next, the alignment layer 37 for retardation layer is baked and then rubbed to impart alignment control ability (P-3). Here, rubbing is used in order to provide alignment control ability, but the liquid crystal monomer to be applied next may be aligned, such as a photo alignment film, an ion beam alignment film, and a stretched film, instead of rubbing.

  The retardation layer alignment film 37 is horizontally oriented and has a function of determining the slow axis direction of the retardation layer 38. On the alignment layer 37 for the retardation layer, a polymerization initiator that generates a polymerization initiating species by both ultraviolet light irradiation and heating and a nematic liquid crystal monomer having a reactive functional group at the molecular end are dissolved in an organic solvent. A retardation material to which a polymerization inhibitor for controlling the degree of polymerization and a leveling agent for improving the coating property are added is applied (P-4).

  Examples of nematic liquid crystal monomers having an acrylic group at the molecular terminal as a reactive functional group are the same as those shown as “Chem 1” and “Chem 2” in Example 1.

  Examples of the organic solvent for the retardation material include propylene glycol monomethyl ether acetate, cyclohexanone, ethylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, methoxybutyl acetate, diethylene glycol dimethyl ether, and diethylene glycol methyl ethyl ether. Can be mentioned.

  In addition, as a kind of polymerization initiator that generates a polymerization initiating species by both ultraviolet light irradiation and heating, there is a sulfonium salt compound. The example is the same as that shown in “Chemical Formula 5”. R1 to R3 represent a substituent selected from a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an aryl group, a heteroaryl group, and the like.

  After applying the phase difference material, it is pre-baked for 3 minutes with a hot plate at 70 ° C. to remove the solvent, thereby forming a transparent liquid film (P-5). This liquid film is oriented in the orientation treatment direction of the retardation film orientation film 37 even in an uncured state.

  A portion of the liquid film corresponding to the reflective display portion is selectively irradiated with ultraviolet light using an exposure mask having an opening, and a transparent film (retardation layer) 38 in which liquid crystal molecules are aligned by the alignment film is formed. Form (P-6). By irradiating the polymerization initiator with ultraviolet light, a polymerization initiating species is generated, the nematic liquid crystal monomer is polymerized and retained while maintaining the alignment, and the liquid crystal molecules become a transparent film aligned by the alignment film. . The unexposed portion maintains the orientation by the orientation control ability of the orientation film and is in an uncured liquid film state.

  FIG. 5 is a diagram for explaining the absorption wavelength of the polymerization initiator. When the absorption spectrum of the liquid crystal monomer is shown by a in FIG. 5 and the absorption spectrum of the polymerization initiator is b, the absorption wavelength of the liquid crystal monomer is longer. Light is absorbed by the liquid crystal monomer, and the polymerization initiator can hardly absorb ultraviolet light, and polymerization initiation species are hardly generated.

  On the other hand, when the absorption spectrum of the liquid crystal monomer is indicated by a, and the absorption spectrum of the polymerization initiator is c, the absorption wavelength of the polymerization initiator is longer than that of the liquid crystal monomer, and therefore absorbs ultraviolet light. Polymerization initiating species can be generated efficiently.

  Therefore, the wavelength longer than the absorption wavelength of the liquid crystal monomer to be used, such as those in which aromatic substituents or substituents obtained by extending a conjugated system are introduced into the R1-R3 portion of the sulfonium salt shown in “Chemical Formula 5” in the previous term I chose the one that stretched out. Furthermore, in the subsequent step (P-30), since it is necessary to generate a polymerization initiating species by thermal energy, a polymerization initiator that causes a polymerization reaction in a temperature range as described later was selected.

  On the other hand, when the absorption wavelength of the polymerization initiator extends to the visible range, the phase difference phase is colored, which is not desirable because the color performance as a color filter is deteriorated. However, a polymerization initiator having a thermal bleaching (bleaching) function can be used without problems because absorption disappears when heated in the visible region.

  In addition to the sulfonium salt compounds, other compounds such as peroxides and iodonium salts can be used in the present invention by optimizing the absorption wavelength.

  Next, it heats to 140 degreeC or more, the liquid film which was not exposed is hardened, and the transparent film in which the liquid crystal molecule is not oriented is formed (P-20). Since the heating temperature at this time is higher than the liquid crystal phase-isotropic phase transition temperature of the liquid crystal monomer, the liquid crystal monomer exists in a random orientation without being aligned. At this time, since the heating temperature is equal to or higher than the polymerization start temperature of the thermal polymerization initiator, a polymerization reaction of the liquid crystal monomer occurs. As a result, the liquid crystal monomer is cured in a random state, so that a transparent film having no phase difference is formed.

  The thermal reactivity required for the polymerization initiator is that the polymerization reaction does not start below the liquid crystal phase-isotropic phase transition temperature of the liquid crystal monomer, and the polymerization reaction occurs at a temperature above the liquid crystal phase-isotropic phase transition temperature. It is necessary to generate the polymerization initiating species necessary for the production. Further, if the temperature is too high, the liquid crystal monomer is decomposed, so that curing must be started at a temperature lower than the decomposition temperature of the liquid crystal monomer. Therefore, also in this example, as in Example 1, the half-life of the polymerization initiator is preferably 10 minutes or longer at 70 ° C. and preferably within 1 hour at 230 ° C.

  As described above, in this example, only by adding one kind of polymerization initiator to the liquid crystal monomer, the polymerization initiating species is generated by either light irradiation or heating. Therefore, a plurality of polymerization initiators are used as in Example 1. Therefore, the concentration of the polymerization initiator with respect to the liquid crystal monomer can be kept low.

  Next, a transparent organic layer is applied on the retardation layer 38 to form the second protective layer 40 (P-9). The protective layer 40 also serves as a barrier layer that blocks decomposition products during the polymerization reaction of the retardation layer.

  If the retardation layer 38 has a Δn larger than twice that of the liquid crystal layer, the thickness of the retardation layer 38 becomes insufficient when the retardation is set to a half wavelength, and only the retardation layer 38 is used. Then, the difference in retardation between the reflective display portion and the transmissive display portion is smaller than a quarter wavelength. Therefore, in order to secure a quarter-wave retardation difference between the reflective display portion and the transmissive display portion, a film thickness adjusting layer 39 is then formed on the retardation layer 38. A photosensitive transparent resist is applied to the second protective layer 40, and ultraviolet light is selectively irradiated using an exposure mask. Here, patterning is performed using an exposure mask having a distribution similar to that of the reflective display portion. Thereafter, the film thickness adjusting layer 39 is formed only on the upper layer of the retardation layer 38 by alkali development (P-10). Further, a columnar spacer for maintaining the gap of the liquid crystal layer is formed thereon (P-11).

  The first liquid crystal alignment film 33 is applied to the uppermost layer of the main surface of the first substrate 31, and the second liquid crystal alignment film 34 is applied to the uppermost layer of the main surface of the second substrate 32, and a rubbing process (P -12), columnar spacers are interposed in the display areas of the first substrate 31 and the second substrate 32, a sealing material is applied to the inside of the outer peripheral edge, the two substrates are bonded together, and assembled, and the liquid crystal layer on the inside 10 is enclosed (P-13).

  Finally, the first polarizing plate 41 and the second polarizing plate 42 are disposed outside the first substrate 31 and the second substrate 32, respectively. The transmission axes of the first polarizing plate 41 and the second polarizing plate 42 are arranged so as to be orthogonal and parallel to the alignment direction of the liquid crystal layer (P-14).

  In this embodiment, the light diffusive pressure-sensitive adhesive layer 43 in which a large number of transparent microspheres having a refractive index different from that of the pressure-sensitive adhesive material is mixed is used for the pressure-sensitive adhesive layer 43 of the first polarizing plate 41. With such a configuration, the optical path of incident light is expanded by utilizing the effect of refraction caused by the difference in refractive index between the adhesive material and the microsphere. Thereby, it is possible to reduce iridescent coloring caused by interference of reflected light between the pixel electrode 28 and the common electrode 29. However, the configuration of the adhesive layer 43 is not limited to this, and it goes without saying that an adhesive material without microspheres may be used.

  In the transmissive display portion of the transflective liquid crystal panel of this example manufactured as described above, the transmission axis of the first polarizing plate 41 and the transmission axis of the second polarizing plate 42 are orthogonal to each other, and the latter is the liquid crystal alignment. Parallel to the direction. Since this is the same configuration as that of the transmissive IPS system, a wide viewing angle that can withstand monitor applications can be obtained for transmissive display as in the transmissive IPS system.

  In this embodiment, the liquid crystal display panel structure and manufacturing process of the IPS type transflective liquid crystal display device with built-in phase difference have been described. However, the transflective liquid crystal panel with built-in phase difference of the VA type and other liquid crystal driving methods. The present invention can also be used in In that case, the TFT structure, the pixel structure of the color filter, the retardation value of the retardation layer, and other panel configurations may differ depending on the liquid crystal drive method, but polymerization will start when the retardation material is irradiated with either ultraviolet light or heating. By adding an appropriate polymerization initiator for generating seeds, the process of the present invention can be carried out, and the effect is exhibited.

  The planar configuration of the transflective liquid crystal display device according to the third embodiment of the present invention is the same as that of FIG. 6 is a cross-sectional view taken along the line A-A ′ of FIG. 1 for explaining the cross-sectional structure of the third embodiment. FIG. 7 is a flowchart for explaining the manufacturing process of the third embodiment.

  On the main surface (inner surface) of the first substrate 31, a color filter 45 divided by a black matrix 35, a retardation layer alignment film 37, a retardation layer 38, or a transparent layer 100 that has lost the retardation function, and a retardation A protective layer (second protective film) 40 and a first liquid crystal alignment film 33 are sequentially stacked.

  The alignment layer 37 for retardation layer is provided with an alignment control ability for controlling the alignment of the forming material of the retardation layer 38 made of the liquid crystal layer composition. Further, the first liquid crystal alignment film 33 has an alignment control ability for controlling the initial alignment of the liquid crystal layer 10 for controlling display light.

  The main surface of the second substrate 32 has a thin film transistor TFT for driving a pixel. The thin film transistor TFT is connected to the scanning wiring 21, the signal wiring 22, and the pixel electrode 28. In addition, a common wiring 23 and a common electrode 29 are provided. Here, the thin film transistor TFT has an inverted staggered structure, and its channel portion is formed of an amorphous silicon (a-Si) layer 25. The scanning wiring 21 and the signal wiring 22 intersect with each other in the row direction and the column direction to form a two-dimensional matrix, and the thin film transistor TFT is roughly located near the intersection.

  The common wiring 23 is arranged in parallel with the scanning wiring 21 and is connected to the common electrode 23 through the second through hole 27. The pixel electrode 28 and the source / drain electrode 24 of the thin film transistor TFT are coupled by a first through hole 26. A second liquid crystal alignment film 34 is provided on the pixel electrode 28 and has an alignment control ability for controlling the initial alignment of the liquid crystal layer 10.

  The first substrate 31 in the present embodiment is preferably made of borosilicate glass with few ionic impurities and has a thickness of 0.5 mm, for example. The color filter 45 partitioned by the black matrix 35 has red, green, and blue portions (color subpixels) arranged repeatedly in a stripe pattern, and each stripe is parallel to the signal electrode 22. The first liquid crystal alignment film 33 is a polyimide polymer film and has been subjected to alignment treatment by a rubbing method.

  The second substrate 32 is suitably borosilicate glass similar to the first substrate 31 and has a thickness of 0.5 mm, for example. Similarly to the first liquid crystal alignment film 33, the second liquid crystal alignment film 34 is a horizontal alignment polyimide polymer film. The signal wiring 22, the scanning wiring 21, and the common wiring 23 are formed of aluminum (Al), an alloy thereof (alloy of aluminum and neodymium: Al—Nd), chromium (Cr), or the like, and the pixel electrode 28 is formed of indium. A transparent conductive film such as tin oxide (indium tin oxide: ITO) is desirable, and the common electrode 29 is also desirably formed of a transparent conductive film such as ITO.

  The pixel electrode 28 has slits 30 parallel to the scanning wiring 21 and the pitch of the slits 30 is about 4 μm. The pixel electrode 28 and the common electrode 29 are separated by a third insulating layer 53 having a layer thickness of 0.5 μm, and an electric field is formed between the pixel electrode 28 and the common electrode 29 when a voltage is applied. Due to the influence of the insulating layer 53, the electric field is distorted in an arch shape and passes through the liquid crystal layer 10. As a result, an orientation change occurs in the liquid crystal layer 10 when a voltage is applied. The above numerical values are merely examples including other numerical values in the present specification and drawings, and the present invention is not limited to these numerical values.

  The common wiring 23 has a structure projecting into the pixel electrode 28 at a portion intersecting with the pixel electrode 28. In FIG. 1, the portion where the common wiring 23 overlaps with the pixel electrode 28 is a reflective display portion, and the other portion where the pixel electrode 28 and common electrode 29 overlap is a transmissive display portion through the backlight. . Since the optimum layer thickness of the liquid crystal layer is different between the transmissive display portion and the reflective display portion, a step is generated at the boundary. In order to shorten the boundary between the transmissive display unit and the reflective display unit, the transmissive display unit and the reflective display unit are arranged so that the boundary is parallel to the short side of the pixel.

  Thus, if the wiring such as the common wiring 23 is also used as a reflector, an effect of reducing the manufacturing process can be obtained. If the common wiring 23 is made of aluminum having a high reflectance, a brighter reflective display can be obtained. The same effect can be obtained even if the common wiring 23 is made of chromium and a reflector made of aluminum or silver alloy is separately formed.

  The liquid crystal layer 10 is a liquid crystal layer composition exhibiting positive dielectric anisotropy in which the dielectric constant in the alignment direction is larger than that in the normal direction. Here, the birefringence is 0.067 at 25 ° C., and a nematic phase is exhibited in a wide temperature range including a room temperature region. In addition, during a holding period when driving at a frequency of 60 Hz using a thin film transistor, a high resistance value that does not cause flicker by sufficiently holding reflectance and transmittance is exhibited.

  FIG. 7 is a flowchart for explaining a manufacturing process of a liquid crystal panel constituting Embodiment 3 of the liquid crystal display device of the present invention. The manufacturing process of FIG. 7 will be described with reference to the structure of the liquid crystal panel of FIG.

  A black matrix 35 and a color filter 45 are formed on the main surface of the first substrate 31 (P-1).

  Next, an alignment film 37 for retardation layer is applied (P-2).

  Next, the alignment layer 37 for retardation layer is baked and then rubbed to impart alignment control ability (P-3). Here, rubbing is used in order to provide alignment control ability, but the liquid crystal monomer to be applied next may be aligned, such as a photo alignment film, an ion beam alignment film, and a stretched film, instead of rubbing.

  The retardation layer alignment film 37 is horizontally oriented and has a function of determining the slow axis direction of the retardation layer 38. A polymerization inhibitor that controls the degree of polymerization by dissolving a nematic liquid crystal monomer having a reactive functional group at the molecular end, a photopolymerization initiator, and a thermal polymerization initiator in an organic solvent on the alignment layer 37 for retardation layer. And a phase difference material to which a leveling agent for improving applicability is added is applied (P-4).

  Examples of nematic liquid crystal monomers having an acrylic group (acrylate) at the molecular end as a reactive functional group are the same as the above-mentioned “Chemical Formula 1” and “Chemical Formula 2”. The reactive functional group is not an acrylic group, but may be an epoxy group or the like as long as a polymerization reaction occurs.

  Further, as photopolymerization initiators, IRGACURE 651, IRGACURE 184, DAROCUR 1173, IRGACURE 500, IRGACURE 2959, IRGACURE 127, IRGACURE IR, IRGACURE IR, IRGACURE IR, IRGACURE IR IRGACURE 4265, DAROCUR TPO, IRGACURE 819, IRGACURE 819DW, IRGACURE 784, IRGACURE OX 01, IRGACURE OXE 02, IRGACURE 754, and the like.

  Examples of the organic solvent for the retardation material include propylene glycol monomethyl ether acetate, cyclohexanone, ethylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, methoxybutyl acetate, diethylene glycol dimethyl ether, and diethylene glycol methyl ethyl ether. be able to.

  Moreover, there are mainly types of thermal polymerization initiators that generate radicals by heating and those that generate cations by heating. Examples of the thermal polymerization initiator that generates radicals by heating include peroxide compounds. An example of this is shown in “Chemical Formula 3”. R1 to R4 represent a substituent selected from a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an aryl group, a heteroaryl group, and the like, and n represents an integer of 1 to 10.

  In addition, as thermal polymerization initiators that generate cations by heating, there are compounds of sulfonium salts and iodonium salts. Examples thereof are shown in the above “Chemical 4” and “Chemical 5”, respectively. R1 to R3 represent a substituent selected from a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an aryl group, a heteroaryl group, and the like.

  After applying the phase difference material, it is pre-baked for 3 minutes with a hot plate at 70 ° C. to remove the solvent, thereby forming a transparent liquid film (P-5). This liquid film is oriented in the orientation treatment direction of the retardation film orientation film 37 even in an uncured state.

  The liquid film is selectively irradiated with ultraviolet light using an exposure mask having an opening, and a transparent film (retardation layer) 38 in which liquid crystal molecules are aligned is formed by the alignment film. (P-6). At this time, by irradiating the photopolymerization initiator with ultraviolet light, a polymerization initiating species is generated, the nematic liquid crystal monomer is polymerized and retained while maintaining the alignment, and the liquid crystal molecules are aligned by the alignment film. It becomes a transparent film. On the other hand, the unexposed part maintains the orientation by the orientation control ability of the orientation film and is in an uncured liquid film state. In addition, the film concentration is adjusted by appropriately adjusting the solution concentration and the coating conditions during coating so that the retardation of the retardation layer 38 becomes a half wavelength at a wavelength of 550 nm.

  Then, it heats to 140 degreeC or more, the liquid film which was not exposed is hardened, and the transparent film in which the liquid crystal molecule is not oriented is formed (P-30). Since the heating temperature at this time is higher than the liquid crystal phase-isotropic phase transition temperature of the nematic liquid crystal monomer, the liquid crystal monomer exists in a random orientation without being aligned. At this time, since the heating temperature is equal to or higher than the polymerization start temperature of the thermal polymerization initiator added to the retardation material, a polymerization reaction of the liquid crystal monomer occurs. As a result, the liquid crystal monomer is cured in a random state, so that a transparent film having no phase difference is formed. In addition, when using the polymerization initiator which generate | occur | produces a radical, the reactivity raises by performing on the conditions which are hard to receive oxygen inhibition, such as heating by nitrogen atmosphere.

  The conditions required for the thermal polymerization initiator are that the polymerization reaction does not start below the liquid crystal phase-isotropic phase transition temperature of the liquid crystal monomer, and the concentration required for the polymerization reaction at a temperature above the liquid crystal phase-isotropic phase transition temperature. It is necessary to generate a polymerization initiating species. In addition, since the liquid crystal monomer is decomposed when the temperature is too high, curing must be started at a temperature lower than the decomposition temperature of the liquid crystal monomer.

  Here, although it is the same as that of Example 1, the half life of a thermal-polymerization initiator is demonstrated using FIG. The thermal polymerization initiator causes a reaction to generate a polymerization initiating species by thermal energy. Even if the thermal polymerization initiator has a high activation energy, it reacts little by little at room temperature. Therefore, the reactivity of the polymerization initiator is expressed as a half-life. The half-life is the time until half of the molecules react with the initial number of molecules. For example, the half-life of the molecule indicated by the line A in FIG. 4 is 10 minutes, and the half-life of the molecule indicated by the line B is 60 minutes. The number of polymerization initiating species generated by heating is determined by the temperature, half-life and concentration of the polymerization initiator.

  In this example, it is desirable that the half-life of the thermal polymerization initiator at 70 ° C. is 10 minutes or longer so that the polymerization reaction does not start in the step (P-5) of heating with a 70 ° C. hot plate. Moreover, since liquid crystal molecules are decomposed when the temperature is too high, it is desirable that the half-life of the thermal polymerization initiator at 230 ° C. is within 1 hour. Any thermal polymerization initiator satisfying the above conditions can be used other than those represented by “Chemical Formula 3”, “Chemical Formula 4”, and “Chemical Formula 5”.

In this way, it is possible to react the uncured portion only by heating to form a transparent film having no retardation function, so that organic development is performed as in known examples, or the entire surface is exposed. This is not necessary, and can be performed with a simple apparatus configuration and with a simple process.
Next, a transparent organic layer is applied on the retardation layer 38 to form the second protective layer 40 (P-9). The protective layer 40 also serves as a barrier layer that blocks decomposition products during the polymerization reaction of the retardation layer.

  If the retardation layer 38 has a Δn larger than twice that of the liquid crystal layer, the thickness of the retardation layer 38 becomes insufficient when the retardation is set to a half wavelength, and only the retardation layer 38 is used. Then, the difference in retardation between the reflective display portion and the transmissive display portion is smaller than a quarter wavelength. Therefore, in order to secure a quarter-wave retardation difference between the reflective display portion and the transmissive display portion, a film thickness adjusting layer 39 is then formed on the retardation layer 38. A photosensitive transparent resist is applied to the second protective layer 40, and ultraviolet light is selectively irradiated using an exposure mask. Here, patterning is performed using an exposure mask having a distribution similar to that of the reflective display portion. Thereafter, the film thickness adjusting layer 39 is formed only on the upper layer of the retardation layer 38 by alkali development (P-10). Further, a columnar spacer for maintaining the gap of the liquid crystal layer is formed thereon (P-11).

  The first liquid crystal alignment film 33 is applied to the uppermost layer of the main surface of the first substrate 31, and the second liquid crystal alignment film 34 is applied to the uppermost layer of the main surface of the second substrate 32, and a rubbing process (P -12), columnar spacers are interposed in the display areas of the first substrate 31 and the second substrate 32, a sealing material is applied to the inside of the outer peripheral edge, the two substrates are bonded together, and assembled, and the liquid crystal layer on the inside 10 is enclosed (P-13).

  Finally, the first polarizing plate 41 and the second polarizing plate 42 are disposed outside the first substrate 31 and the second substrate 32, respectively. The transmission axes of the first polarizing plate 41 and the second polarizing plate 42 are arranged so as to be orthogonal and parallel to the alignment direction of the liquid crystal layer (P-14).

  In this embodiment, the light diffusive pressure-sensitive adhesive layer 43 in which a large number of transparent microspheres having a refractive index different from that of the pressure-sensitive adhesive material is mixed is used for the pressure-sensitive adhesive layer 43 of the first polarizing plate 41. With such a configuration, the optical path of incident light is expanded by utilizing the effect of refraction caused by the difference in refractive index between the adhesive material and the microsphere. Thereby, it is possible to reduce iridescent coloring caused by interference of reflected light between the pixel electrode 28 and the common electrode 29. However, the configuration of the adhesive layer 43 is not limited to this, and it goes without saying that an adhesive material without microspheres may be used.

  In the transmissive display portion of the transflective liquid crystal panel of this example manufactured as described above, the transmission axis of the first polarizing plate 41 and the transmission axis of the second polarizing plate 42 are orthogonal to each other, and the latter is the liquid crystal alignment. Parallel to the direction. Since this is the same configuration as that of the transmissive IPS system, a wide viewing angle that can withstand monitor applications can be obtained for transmissive display as in the transmissive IPS system.

In this embodiment, the liquid crystal display panel structure and the manufacturing process of the IPS type transflective liquid crystal display device with a built-in phase difference have been described. The invention can also be used for devices. In this case, the TFT structure, color filter pixel structure, retardation layer retardation value, and other panel configurations may differ depending on the liquid crystal drive method. However, by adding an appropriate thermal polymerization initiator to the retardation material. The process of the present invention can be carried out and the effect is exhibited.

    A fourth embodiment of the present invention will be described with reference to the process flow of FIG. 7 using the plan view of FIG. 1 and the cross-sectional view of FIG.

  First, the black matrix 35 and the color filter 45 are formed on the main surface of the first substrate 31 (P-1).

  Next, an alignment film 37 for retardation layer is applied (P-2).

  Next, the alignment layer 37 for retardation layer is baked and then rubbed to impart alignment control ability (P-3). Here, rubbing is used in order to provide alignment control ability, but the liquid crystal monomer to be applied next may be aligned, such as a photo alignment film, an ion beam alignment film, and a stretched film, instead of rubbing.

  The retardation layer alignment film 37 is horizontally oriented and has a function of determining the slow axis direction of the retardation layer 38. On the alignment layer 37 for the retardation layer, a polymerization initiator that generates a polymerization initiating species by both ultraviolet light irradiation and heating and a nematic liquid crystal monomer having a reactive functional group at the molecular end are dissolved in an organic solvent. A retardation material to which a polymerization inhibitor for controlling the degree of polymerization and a leveling agent for improving the coating property are added is applied (P-4).

  Examples of nematic liquid crystal monomers having an acrylic group at the molecular terminal as a reactive functional group are shown in “Chemical Formula 1” and “Chemical Formula 2” described above.

  Examples of the organic solvent for the retardation material include propylene glycol monomethyl ether acetate, cyclohexanone, ethylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, methoxybutyl acetate, diethylene glycol dimethyl ether, and diethylene glycol methyl ethyl ether. be able to.

  In addition, as a kind of polymerization initiator that generates a polymerization initiating species by both ultraviolet light irradiation and heating, there is a sulfonium salt compound. An example is shown in “Chemical Formula 5”. R1 to R3 represent a substituent selected from a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an aryl group, a heteroaryl group, and the like.

  After applying the phase difference material, it is pre-baked for 3 minutes with a hot plate at 70 ° C. to remove the solvent, thereby forming a transparent liquid film (P-5). This liquid film is oriented in the orientation treatment direction of the retardation film orientation film 37 even in an uncured state.

  A portion of the liquid film corresponding to the reflective display portion is selectively irradiated with ultraviolet light using an exposure mask having an opening, and a transparent film (retardation layer) 38 in which liquid crystal molecules are aligned by the alignment film is formed. Form (P-6). By irradiating the polymerization initiator with ultraviolet light, a polymerization initiating species is generated, the nematic liquid crystal monomer is polymerized and retained while maintaining the alignment, and the liquid crystal molecules become a transparent film aligned by the alignment film. . The unexposed portion maintains the orientation by the orientation control ability of the orientation film and is in an uncured liquid film state.

  The outline about the absorption wavelength of a polymerization initiator is demonstrated in FIG. If the absorption spectrum of the liquid crystal monomer is a in FIG. 9 and the absorption spectrum of the polymerization initiator is b, the absorption wavelength of the liquid crystal monomer is longer. The polymerization initiator can hardly absorb ultraviolet light, and polymerization initiation species are hardly generated.

  On the other hand, when the absorption spectrum of the liquid crystal monomer is a, and the absorption spectrum of the polymerization initiator is c, the absorption wavelength of the polymerization initiator is longer than that of the liquid crystal monomer. Can be generated efficiently.

  For this reason, the R 1 to R 3 portion of the sulfonium salt shown in “Chemical Formula 5” is introduced with an aromatic substituent or a substituent having a conjugated system extended to a longer wavelength than the absorption wavelength of the liquid crystal monomer used. I chose something. Furthermore, in the subsequent step (P-30), since it is necessary to generate a polymerization initiating species with thermal energy, a polymerization initiator that causes a polymerization reaction in the temperature range as described later was selected.

  On the other hand, when the absorption wavelength of the polymerization initiator extends to the visible range, the phase difference phase is colored, which is not desirable because the color performance as a color filter is deteriorated. However, a polymerization initiator having a thermal bleaching (bleaching) function can be used without problems because absorption disappears when heated in the visible region.

  In addition to the sulfonium salt compounds, other compounds such as peroxides and iodonium salts can be used in the present invention by optimizing the absorption wavelength.

  Next, it heats to 140 degreeC or more, the liquid film which was not exposed is hardened, and the transparent film in which the liquid crystal molecule is not oriented is formed (P-30). Since the heating temperature at this time is higher than the liquid crystal phase-isotropic phase transition temperature of the liquid crystal monomer, the liquid crystal monomer exists in a random orientation without being aligned. At this time, since the heating temperature is equal to or higher than the polymerization start temperature of the thermal polymerization initiator, a polymerization reaction of the liquid crystal monomer occurs. As a result, the liquid crystal monomer is cured in a random state, so that a transparent film having no phase difference is formed.

  The thermal reactivity required for the polymerization initiator is that the polymerization reaction is not started at a temperature lower than the liquid crystal phase-isotropic phase transition temperature of the liquid crystal monomer, and the polymerization reaction is performed at a temperature higher than the liquid crystal phase-isotropic phase transition temperature. It is necessary to generate the polymerization initiating species necessary for this. Further, if the temperature is too high, the liquid crystal monomer is decomposed, so that curing must be started at a temperature lower than the decomposition temperature of the liquid crystal monomer. Therefore, also in this example, as in Example 1, the half-life of the polymerization initiator is preferably 10 minutes or longer at 70 ° C. and preferably within 1 hour at 230 ° C.

  As described above, in this example, only by adding one kind of polymerization initiator to the liquid crystal monomer, the polymerization initiating species is generated by either light irradiation or heating. Therefore, a plurality of polymerization initiators are used as in Example 1. Therefore, the concentration of the polymerization initiator with respect to the liquid crystal monomer can be kept low.

  Next, a transparent organic layer is applied on the retardation layer 38 to form the second protective layer 40 (P-9). The protective layer 40 also serves as a barrier layer that blocks decomposition products during the polymerization reaction of the retardation layer.

  If the retardation layer 38 has a Δn larger than twice that of the liquid crystal layer, the thickness of the retardation layer 38 becomes insufficient when the retardation is set to a half wavelength, and only the retardation layer 38 is used. Then, the difference in retardation between the reflective display portion and the transmissive display portion is smaller than a quarter wavelength. Therefore, in order to secure a quarter-wave retardation difference between the reflective display portion and the transmissive display portion, a film thickness adjusting layer 39 is then formed on the retardation layer 38. A photosensitive transparent resist is applied to the second protective layer 40, and ultraviolet light is selectively irradiated using an exposure mask. Here, patterning is performed using an exposure mask having a distribution similar to that of the reflective display portion. Thereafter, the film thickness adjusting layer 39 is formed only on the upper layer of the retardation layer 38 by alkali development (P-10). Further, a columnar spacer for maintaining the gap of the liquid crystal layer is formed thereon (P-11).

  The first liquid crystal alignment film 33 is applied to the uppermost layer of the main surface of the first substrate 31, and the second liquid crystal alignment film 34 is applied to the uppermost layer of the main surface of the second substrate 32, and a rubbing process (P -12), columnar spacers are interposed in the display areas of the first substrate 31 and the second substrate 32, a sealing material is applied to the inside of the outer peripheral edge, the two substrates are bonded together, and assembled, and the liquid crystal layer on the inside 10 is enclosed (P-13).

  Finally, the first polarizing plate 41 and the second polarizing plate 42 are disposed outside the first substrate 31 and the second substrate 32, respectively. The transmission axes of the first polarizing plate 41 and the second polarizing plate 42 are arranged so as to be orthogonal and parallel to the alignment direction of the liquid crystal layer (P-14).

  In this embodiment, the light diffusive pressure-sensitive adhesive layer 43 in which a large number of transparent microspheres having a refractive index different from that of the pressure-sensitive adhesive material is mixed is used for the pressure-sensitive adhesive layer 43 of the first polarizing plate 41. With such a configuration, the optical path of incident light is expanded by utilizing the effect of refraction caused by the difference in refractive index between the adhesive material and the microsphere. Thereby, it is possible to reduce iridescent coloring caused by interference of reflected light between the pixel electrode 28 and the common electrode 29. However, the configuration of the adhesive layer 43 is not limited to this, and it goes without saying that an adhesive material without microspheres may be used.

  In the transmissive display portion of the transflective liquid crystal panel of the present example produced as described above, the transmission axis of the first polarizing plate 41 and the transmission axis of the second polarizing plate 42 are orthogonal, and the latter is the liquid crystal alignment. Parallel to the direction. Since this is the same configuration as that of the transmissive IPS system, a wide viewing angle that can withstand monitor applications can be obtained for transmissive display as in the transmissive IPS system.

  In this embodiment, the panel structure and the manufacturing process of the IPS type built-in phase difference type transflective liquid crystal panel have been described. However, the display of the VA type and other liquid crystal driving type built-in phase difference type transflective liquid crystal display device is described. The present invention can also be used in a panel. In this case, the TFT structure, color filter pixel structure, retardation layer retardation value, and other panel configurations may differ depending on the liquid crystal drive system, but the retardation material may be polymerized by either ultraviolet light irradiation or heating. By adding an appropriate polymerization initiator for generating seeds, the process of the present invention can be carried out, and the effect is exhibited.

  For transflective liquid crystal panels, the process of forming the built-in retardation layer can be simplified and manufacturing costs can be reduced. Moreover, the environmental load accompanying the manufacture is reduced.

It is a top view explaining the schematic structural example of 1 pixel of the liquid crystal panel which the liquid crystal display device by this invention comprises. FIG. 3 is a cross-sectional view taken along line A-A ′ of FIG. 1 for explaining a schematic configuration example of one pixel of a liquid crystal display device in which a retardation layer of Example 1 and Example 2 is formed. It is explanatory drawing of the manufacturing process of the liquid crystal panel which comprises the liquid crystal display device of Example 1 and Example 2. FIG. It is the schematic explaining the half life of a polymerization initiator. It is the schematic explaining the absorption wavelength of a polymerization initiator. FIG. 6 is a cross-sectional view taken along line A-A ′ of FIG. 1 for explaining a schematic configuration example of one pixel of a liquid crystal display device in which a retardation layer of Example 3 and Example 4 is formed. It is explanatory drawing of the manufacturing process of the liquid crystal panel which comprises the liquid crystal display device of Example 3 and Example 4. FIG. It is sectional drawing explaining the schematic structural example of 1 pixel of the liquid crystal display device which formed the phase difference layer using organic image development. It is explanatory drawing of the manufacturing process of the liquid crystal panel which passed through the process of forming a phase difference layer using organic image development. It is sectional drawing explaining the schematic structural example of 1 pixel of the liquid crystal display device which formed the phase difference layer using the whole surface heating exposure. It is explanatory drawing of the manufacturing process of the liquid crystal panel which passed through the process of forming a phase difference layer using whole surface heating exposure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Liquid crystal layer, 21 ... Scan wiring, 22 ... Signal wiring, 23 ... Common wiring, 25 ... Amorphous silicon layer, 26 ... Through hole, 27 ... Through hole, 28 ... Pixel electrode, 29 ... Common electrode, 30 ... Slit, DESCRIPTION OF SYMBOLS 31 ... 1st board | substrate, 32 ... 2nd board | substrate, 33 ... 1st liquid crystal aligning film 34 ... 2nd liquid crystal aligning film, 35 ... Black matrix, 36 ... Overcoat film, 37 ... Orientation film for retardation layers , 38 ... retardation layer, 39 ... film thickness adjusting layer, 40 ... flattening layer, 41 ... first polarizing plate, 42 ... second polarizing plate, 43 ... adhesive layer, 45 ... color filter, 51 ... first Insulating layer, 52 ... second insulating layer, 53 ... third insulating layer, 61 ... transmitted light, 62 ... reflected light, 100 ... transparent film in which the phase difference function is lost.

Claims (9)

A light shielding pattern, an alignment film for retardation formed on the light shielding pattern, a transparent organic film formed on the alignment film for retardation, and an insulating film formed on the transparent organic film on a main surface A first substrate formed on
A second substrate having a thin film transistor and a pixel electrode driven by the thin film transistor formed on a main surface;
A transflective liquid crystal display device comprising a liquid crystal layer sandwiched between the first substrate and the second substrate via a liquid crystal alignment film,
The transparent organic film is composed of liquid crystal molecules, and is divided into a first region in which the liquid crystal molecules are aligned by the retardation film and a second region in which the liquid crystal molecules are not aligned by the retardation film,
The translucent liquid crystal display device, wherein the transparent organic film contains an iodonium salt, a sulfonium salt, and a peroxide-based compound or decomposition product. A light shielding pattern, a retardation film formed on the light shielding pattern, a transparent organic film formed on the retardation film, and an insulating film formed on the transparent organic film on a main surface A first substrate formed on
A second substrate having a thin film transistor and a pixel electrode driven by the thin film transistor formed on a main surface;
A transflective liquid crystal display device comprising a liquid crystal layer sandwiched between the first substrate and the second substrate via a liquid crystal alignment film,
The transparent organic film is composed of liquid crystal molecules, and is divided into a first region in which the liquid crystal molecules are aligned by the retardation film and a second region in which the liquid crystal molecules are not aligned by the retardation film,
The translucent liquid crystal display device, wherein the transparent organic film contains elements of iodine and fluorine or sulfur and fluorine. Method for manufacturing transflective liquid crystal display device including first substrate, second substrate, and liquid crystal layer sandwiched between liquid crystal alignment film between first substrate and second substrate Because
A first step of forming a light shielding pattern on the first substrate;
A second step of forming a retardation film on the light shielding pattern;
On the alignment film for retardation, a liquid film containing a photopolymerization initiator that generates a polymerization initiating species by ultraviolet light irradiation, a thermal polymerization initiator that generates a polymerization initiating species by heating, and a liquid crystal molecule having a reactive site, Alternatively, a third step of forming a liquid film containing a thermal polymerization initiator that generates a polymerization initiating species by either ultraviolet light irradiation or heating and a liquid crystal molecule having a reactive site;
A fourth step of selectively irradiating the liquid film with ultraviolet light to form a transparent organic film in which the liquid crystal molecules are aligned by the retardation film;
The substrate is heated to a temperature higher than the liquid crystal phase-isotropic phase transition temperature of the liquid crystal molecules and the thermal polymerization initiator generates a polymerization initiation species having a polymerization initiation concentration by heat, and the liquid crystal molecules are aligned for the retardation. A fifth step of forming a transparent organic film that is not oriented by the film;
A sixth step of forming an insulating film on the transparent organic film;
A method of manufacturing a transflective liquid crystal display device, comprising: In claim 3,
The method for producing a transflective liquid crystal display device, wherein the thermal polymerization initiator generates a radical which is a polymerization initiating species by heating. In claim 3 or 4,
The method for producing a transflective liquid crystal display device, wherein the thermal polymerization initiator is a peroxide compound. In claim 3,
The method for producing a transflective liquid crystal display device, wherein the thermal polymerization initiator generates a cation that is a polymerization initiating species by heating. In claim 3 or 6,
The method for producing a transflective liquid crystal display device, wherein the thermal polymerization initiator is a compound of either a sulfonium salt or an iodonium salt. In any of claims 3 to 7,
A method for producing a transflective liquid crystal display device, wherein the half-life of the thermal polymerization initiator is 10 minutes or more at 70 ° C. and within 1 hour at 230 ° C. In any of claims 3 to 8,
A method for producing a transflective liquid crystal display device, wherein the concentration of the thermal polymerization initiator is 0.05 wt% or more and 15 wt% or less with respect to the liquid crystal monomer.

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