Patent Application
20200393727
The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device having a transverse field system liquid crystal panel.
In recent years, an alignment film for photo-alignment has been more adopted in a transverse field crystal liquid display device due to its advantages including low viewing angle dependency, high display quality, and no alignment anomalies generating at the steps in an alignment film for rubbing.
Meanwhile, the alignment film for photo-alignment adopts the non-contact type alignment treatment, therefore, good uniformity of display is ensured, however, foreign substance induced faint bright spots and faint bright spots induced from alignment film cissing portions, which are, even though relatively minute in size, are observed as faint bright spot defects. Therefore, the alignment film for photo-alignment is disadvantageous in having an inclination to generate the faint bright spot defects.
On the other hand, for the alignment film for rubbing, the alignment film is rubbed directly with a cloth, so that a certain degree of alignment is provided even without an alignment film on the substrate surface; therefore, foreign substance induced faint bright spots and faint bright spots induced from alignment film cissing portions are not observed as faint bright spot defects as long as these faint bright spots are relatively small in size. That is, as compared with the alignment film for photo-alignment, a faint bright spot defect is less likely to occur.
Further, in a liquid crystal display device for in-vehicle use, a liquid crystal display device is desired, in which the optimal viewing angle direction is shifted slightly upward with respect to the display surface of the liquid crystal panel. In a transverse field system liquid crystal display device, in order to adjust such an optimum viewing angle direction in a specific direction, it is effective that the liquid crystal molecules are aligned vertically with respect to the display screen, and to control a pretilt angle, which is an initial alignment of the liquid crystal molecules, to a relatively low and appropriate range.
However, in order to obtain an alignment regulation force of a certain level or more in the alignment film for rubbing, rubbing treatment with certain strength is required to be implemented, and the pretilt angle becomes relatively high. Therefore, the control of the pretilt angle to the relatively low range described above is difficult. On the other hand, in the alignment film for photo-alignment, setting the pretilt angle to any degrees other than 0° is difficult. That is, obtaining the above-mentioned shifted slightly upward optimal viewing angle characteristics has been difficult when using either the alignment film for rubbing or the alignment film for photo-alignment.
In addition, instead of simply replacing the disadvantage that the alignment anomalies easily occur at the steps in the alignment film for rubbing with the alignment film for photo-alignment, Japanese Patent Application Laid-Open No. 11-305256 describes a method in which rubbing treatment and photo-alignment treatment are used in combination to suppress the alignment anomalies at steps. In this method, the rubbing treatment and the photo-alignment treatment are used in combination; therefore, the characteristics, obtained with the alignment film for photo-alignment, of the low viewing angle dependency, high display quality, further, characteristics of no alignment anomalies at the steps, and that a faint bright spot defect due to being subjected to the rubbing treatment is less likely to occur, may be obtained.
Here, in the configuration of Japanese Patent Application Laid-Open No. 11-305256, the photo-alignment treatment is combined as an auxiliary role to compensate for the alignment anomalies at the steps due to the rubbing treatment, and a relatively strong rubbing treatment is performed because providing the alignment regulation force to the alignment film is basically assumed to be performed by the rubbing treatment. Therefore, the pretilt angle to be formed is a relatively high pretilt equivalent to that obtained by the rubbing treatment. In other words, in the above configuration, controlling the pretilt angle to a relatively low range to obtain the optimal viewing angle characteristics shifted slightly upward is as difficult as in the general cases with the alignment film for rubbing and the alignment film for photo-alignment.
Provided is a liquid crystal display device capable of adjusting an optimum viewing angle direction in a specific direction and preventing occurrence of a faint bright spot defect.
According to the liquid crystal display device includes an array substrate on which a plurality of thin film transistors are arranged, a counter substrate arranged to face the array substrate, a liquid crystal layer interposed between the array substrate and the counter substrate, and a liquid crystal panel of a transverse field system in which liquid crystal is driven by an electric field generated in a direction parallel to the array substrate and the counter substrate. The liquid crystal panel includes a first alignment film provided on the array substrate side, and a second alignment film provided on the counter substrate side. The first and second alignment films have photo-alignment properties. At least one of the first and second alignment films has a surface on which weak rubbing treatment is performed, of which pushing amount of the rubbing roller in the rubbing treatment is in the range of 0.01 to 0.30 mm.
According to the above-described liquid crystal display device, an optimus viewing angle direction in a specific direction can be set and occurrence of a faint bright spot defect can be prevented.
These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
In the following, a transverse field system liquid crystal panel driven with a thin film transistor (TFT) as a switching element, and in particular, a liquid crystal panel of fringe field switching (FFS) system will be described, as an example.
<Overall Configuration of Liquid Crystal Panel>
An overall configuration of a liquid crystal panel constituting a liquid crystal display device according to the present invention will be described with reference to
The liquid crystal panel 100 illustrated in
The sealing material 130 is arranged in a frame region 190 provided outside the area corresponding to the display area 200. The outer shapes of the array substrate 110 and the counter substrate 120 are both rectangular, and the outer shape of the array substrate 110 is larger than the outer shape of the counter substrate 120 and protrudes in a plan view. In other words, in the drawing, in the side on the lower side and the side on the right side of the edge portion of the array substrate 110, where the signal terminals 118X and 118Y described later are provided, the array substrate 110 has a protruding portion which is outer edge thereof protruding from the outer edge of the counter substrate 120, and is arranged with the counter substrate 120 being superposed thereon.
Note that the frame region 190 is a frame-shaped region that is located outside the display region 200 and surrounds the display region 200 on the array substrate 110, the counter substrate 120, or a region defined by both substrates of the liquid crystal panel 100, that is, the frame region 190 means all areas other than the display area 200 surrounded by a broken line in
Further, between the array substrate 110 and the counter substrate 120, a plurality of columnar spacers (not illustrated) for keeping the gap at a fixed distance are arranged in the display area 200. In other words, the column spacers maintain the distance between the substrates within a certain range. In Embodiment 1, a dual spacer structure in which two different types of columnar spacers are arranged in a mixed manner is used. In this dual spacer structure, for a columnar spacer of a first form is, for example, a spacer having a relatively high height or a spacer having a relatively long length in a direction perpendicular to each substrate surface is used: thereby, the spacer functions as a spacer (referred to as a main spacer) that comes into contact with each substrate surface in normal time and holds between the substrates. Meanwhile, for a columnar spacer of a second form, a spacer having a relatively low height or a spacer having a relatively short length in the direction perpendicular to each substrate surface is used; thereby, the spacer functions as a spacer (referred to as a sub spacer) that does not come into contact with one substrate in normal time but holds between the substrates by coming into contact with the one substrate only when the distance between the substrates is reduced.
The array substrate 110 and the opposing substrate 120, which are a pair of substrates arranged to face each other, are arranged on a glass substrate 111 and a glass substrate 121, which are transparent insulating substrates, respectively.
That is, the counter substrate 120 includes an alignment film 122 (second alignment film) for aligning liquid crystal and color filters 123 provided below the alignment film 122, here, color material layers corresponding to (R), green (G) and blue (B) that are three primary colors are arranged, in, for example, a region corresponding to at least the display region 200 on one main surface of the glass substrate 121 set to a thickness of about 0.3 mm. Further, light shielding layers 124 for shielding light between the color filters 123 are provided. The light shielding layers 124 are also provided so as to shield an area corresponding to the frame region 190 provided outside the display area 200 from light. The light shielding layer 124 may be referred to as a black matrix (BM) 124 in some cases. Further, an overcoat layer (OC layer) 125, which is a transparent resin film for covering the surfaces of the color filters 123 and BMs 124 and planarizing the surface steps of the color filters 123 and BMs 124, is provided below the alignment film 122.
In Embodiment 1, for the alignment film 122 formed on the counter substrate 120, a photo-alignment film having an alignment regulation force by performing photo-alignment treatment on the photo-alignment film material is used, in particular, a phase-separating photo-alignment film having different compositions, properties, and the like on the upper layer side and the lower layer side is used. The alignment film 122 has one of particularly characteristic configurations; therefore, the configuration, the manufacturing method, and the like thereof will be described later in detail.
In addition, the columnar spacers described above are provided between the array substrate 110 and the counter substrate 120, and both the main spacer and the sub spacer are provided in a fixed manner on the surface of the OC layer 125 on the counter substrate 120 side.
Further, on the other main surface of the glass substrate 121 of the counter substrate 120, that is, on the main surface opposite to the main surface on which the color filters 123, BMs 124 and the like are provided, a transparent conductive layer 126 for preventing static electricity that is connected to ground is provided. The transparent conductive layer 126 for preventing static electricity is provided, in a manner, for example, that the transparent conductive layer 126 covers at least the display area 200 of the glass substrate 121 with a transparent conductive film such as an indium tin oxide (ITO) film, and is effective for preventing electro static charge due to static electricity and display failure due to an external electric field in a liquid crystal panel of an in-plane-switching system.
Next, the configuration of the array substrate 110 will be described. The array substrate 110 includes an alignment film 112 (first alignment film) for aligning liquid crystal, a pair of pixel electrodes 113 and counter electrodes 114, which are provided below the alignment film 112 and generate an electric field in a direction parallel to the main surface of the array substrate 110 or the counter substrate 120 to drive the liquid crystal, TFTs 115 for applying a voltage to the pixel electrodes 113, and an insulating film 116 covering the TFTs 115 in. for example, a region corresponding to at least the display region 200 on one main surface of the glass substrate 111 set to a thickness of about 0.3 mm. Further, as illustrated in
Further, the TFT 115 includes a semiconductor layer serving as an active layer of the transistor, and a gate electrode, a source electrode, a drain electrode, and the like provided on the semiconductor layer in an overlapping manner. Note that, illustration of each electrode is omitted. Note that. the gate electrode may be provided as part of the gate wiring 117g (
Further, as illustrated in
Further, in Embodiment 1, the pixel electrode 113 and the counter electrode 114 which make up a pair of electrodes for applying a voltage for driving the liquid crystal are schematically illustrated in the sectional view. The pixel electrode 113, which is one of the electrodes, is formed of a plate-shaped transparent conductive film pattern, and the counter electrode 114, which is the other electrode, is formed of a transparent conductive film pattern of a slit electrode having a plurality of slit-shaped openings provided in parallel in a region overlapping with the pixel electrode 113.
Further, as schematically illustrated in
In addition, the counter electrode 114 is disposed over the pixel electrode 113 via the insulating film 116, at least in a region where the slit electrode is formed. Further, the transparent conductive film pattern forming the counter electrode 114 may have a configuration in which an opening is provided in a region overlapping with the TFT 115.
Further, the configuration and arrangement of the pixel electrode 113 and the counter electrode 114 are not limited to the above, a configuration in which the shape and arrangement of each of the pixel electrode 113 and the counter electrode 114 are reversed, the pixel electrode 113 is disposed in a layer above the counter electrode 114 as a pattern in which comb-tooth shaped or a plurality of slit-shaped openings are formed in parallel, the counter electrode 114 is formed in a plate-shape and disposed below the pixel electrode 113, and the TFT 115 is electrically connected to the pixel electrode 113 having a comb-tooth shaped or a plurality of slit-shaped openings to apply a voltage.
For both the pixel electrode 113 and the counter electrode 114, a comb-tooth shaped comb electrode that has been generally used as an electrode of an in-plane switching system may be used. In the case of a comb electrode, the extension direction of the comb electrode is the vertical direction (Y direction) in the drawing, that is, the up and down direction in the display region 200, similarly to the extension direction of the slit electrode.
Although illustration and description of specific planar pattern shapes of the pixel electrode 113 and the counter electrode 114 are omitted, a planar pattern shape of a pixel electrode and a counter electrode used in a liquid crystal panel using a known FFS system may be adopted.
Also, for the insulating film 116 on the array substrate 110, in the drawing, each insulating film that mutually insulates the semiconductor layer, the gate electrode, the source electrode, and the drain electrode that constitute the TFT 115, and the insulating film that covers the TFT 115, or the insulating film formed between the pixel electrode 113 and the counter electrode 114 and the other insulating films are simplified and illustrated as an integrated insulating film. However, practically, a single-layer transparent insulating film or a laminated film of a plurality of transparent insulating films is formed between each of the electrodes or the like.
Next, the configuration provided on the frame region 190 of the array substrate 110 will be described. As illustrated in
In
And, to the respective electrode pads for the signal terminals 118X and 118Y, a control substrate 132X and a control substrate 132Y are connected in which a control integrated circuit (IC) chip that generates a control signal for controlling a drive IC via a flexible flat cable (FFC) 131 serving as a connection wiring is provided.
The control signals from the control substrates132X and 132Y are input to the driving IC chips 133X and 133Y attached to the protrusions via the signal terminals 118X and 118Y, respectively, and output signals output from the driving IC chips 133X and 133Y are supplied to the TFT 115 in the display area 200 via a plurality of signal extraction wirings (not illustrated) drawn from the display area 200.
Further, as illustrated in
Further, the transparent conductive layer 126 formed on the main surface of the counter substrate 120 is grounded. Although a detailed description of the connection structure is omitted with reference to the drawings, for example, an earth pad is provided on the protruding portion of the array substrate 110, and the transparent conductive layer 126 and the earth pad can be connected via a conductive paste or a conductive tape. A general silver paste can be used as the conductive paste, and a conductive tape obtained by applying a conductive adhesive to a base material of a metal foil such as an Al (aluminum) foil or a Cu (copper) foil can be used as the conductive tape. A common commercially available conductive tape can be used.
Further, a backlight unit (not illustrated) serving as a light source is disposed facing the array substrate 110 on the opposite side of the display area 200 of the liquid crystal panel 100, and an optical sheet (not illustrated) for controlling the polarization state, directivity, and the like of the light is disposed between the liquid crystal panel 100 and the backlight unit.
Further, the liquid crystal panel 100 is housed in a housing (not illustrated) having an opening in a display area portion including the display area 200 of the counter substrate 120 together with the above-described members such as the backlight unit and the optical sheet, and constitutes the liquid crystal display device 10 (
The liquid crystal display device 10 operates as follows. For example, when an electric signal is input from the control substrates 132X and 132Y, a driving voltage is applied to the pixel electrode 113 and the counter electrode 114, and the alignment of the liquid crystal molecules in the liquid crystal layer 140 changes according to the driving voltage. Then, light emitted from the backlight disposed on the back side of the liquid crystal panel 100 is transmitted or blocked to the observer side via the array substrate 110, the liquid crystal layer 140, and the counter substrate 120, so that video is displayed on the display area 200 of the liquid crystal panel 100.
<Configuration of Alignment Film>
Next, for the structure of the alignment film, the structure in the thickness direction of the alignment film 122 formed on the main surface of the counter substrate 120 will be described in detail with reference to
Although a description of a specific method of manufacturing the alignment film 122 is omitted, a phase-separated alignment film formed by transferring and coating a mixed material of two different kinds of precursors and then heating and phase-separating the mixed material is used. An image expressing the configuration of the alignment film 122, which is the structural feature, is a state in which, an alignment agent (a first alignment agent) forming the first layer 122L1 located on the lower layer side and an alignment agent (a second orientation agent) constituting 122L2 forming the second layer located on the upper layer side are mixed and distributed to some extent at the boundary portion, and not clearly separated into two layers on the upper layer side and the lower layer side.
For the structure obtained by phase separation, the two layer structure which is a slightly different depending on the characteristics of the two kinds of materials to be mixed, how the material formed on the lower layer side and the underlayer conform each other, the detailed conditions of the formation process, and the like is obtained. Typically, as to the concentration distribution, on the lower layer side of the alignment film 122, the alignment agent formed of the first layer 122L1, that is, the concentration of the alignment agent mainly contained in the first layer 122L1 is high, and a concentration gradient is gradually reduced from the lower layer toward the upper layer. Meanwhile, on the upper layer side of the alignment film 122, the alignment agent formed of the second layer 122L2, that is, the concentration of the alignment agent mainly contained in the second layer 122L2 is high, and a concentration gradient is gradually reduced from the upper layer toward the lower layer.
In addition, weak rubbing treatment is performed on the surface of the alignment film 122 on the counter substrate 120, and after the rubbing treatment, further, photo-alignment treatment in which predetermined polarized light is irradiated, which is the treatment for aligning an alignment material having photo-alignment properties, is performed. By performing the photo-alignment treatment, a display with good uniformity can be obtained.
As a degree of the weak rubbing treatment, for example, it is desirable to adjust the pushing amount of the rubbing roller in the rubbing treatment to a range of 0.01 to 0.30 mm. By adjusting to this range, a pretilt angle of a minute angle of less than 1° can be given to the liquid crystal molecules.
Although not illustrated in the drawings, the alignment film 112 on the array substrate 110 is also a phase separation type alignment film similar to the alignment film 122, and the same weak rubbing treatment and photo-alignment treatment as the alignment film 122 are performed. Note that the rubbing treatment performed on the surface of the alignment film 122 on the counter substrate 120 and the rubbing treatment performed on the surface of the alignment film 112 on the array substrate 110 are common in that the weak rubbing treatment is performed. However, the anti-parallel alignment treatment is performed such that the alignment directions of the counter substrate 120 and the array substrate 110 are different from each other by 180 degrees.
As a comparative example,
In the liquid crystal panel 100 of Embodiment 1, by providing the alignment films 112 and 122 having the above-described configuration, a minute pretilt angle of less than 1° can be formed between liquid crystal molecules and the alignment films 112 and 122 with good reproducibility.
In the description with reference to
As described above, in the liquid crystal panel 100 of Embodiment 1, the configuration is adopted in which a minute pretilt angle can be formed using the photo alignment film, and further, by utilizing the minute pretilt angle, an optimal direction of the viewing angle with respect to the display area 200, that is, a direction in which the contrast is maximized can be adjusted.
Hereinafter, a configuration capable of adjusting the viewing angle direction will be described in detail with reference to
Also, as illustrated in
Also, as illustrated in
By introducing the optical design described above, in the liquid crystal display device 10 of Embodiment 1, the direction which is slightly higher with respect to the display area 200, that is, the direction that maximizes the contrast when viewed from the +Y direction side slightly in the +Z direction, that is, the optimal viewing angle direction is set, by utilizing the minute pretilt angle. The viewing angle optimized when viewed from a slightly upper side with respect to the display area 200 is particularly suitable for a liquid crystal display device for in-vehicle use.
<Other Effects>
In Embodiment 1 described above, although the description has been made in that, by using the alignment film obtained by performing the weak rubbing treatment and the optical alignment treatment on the material of the alignment film for photo-alignment, the minute pretilt can be formed and used for the viewing angle adjustment, the effect of suppressing the occurrence of foreign substance induced faint bright spots and faint bright spots induced from minute alignment film cissing portions, which are problematic in the general alignment film, can be obtained.
Hereinafter, as another effect of Embodiment 1, an effect of improving resistance to a faint bright spot defect induced from alignment film cissing portions will be described.
The liquid crystal panel 100a illustrated in
Meanwhile, in the liquid crystal panel 100a, as illustrated in
The second layer 122L2 is made of an alignment material having photo-alignment properties; therefore, an alignment state may not be formed in the region of the alignment film cissing portion 122a even if the photo-alignment treatment is performed.
However, in forming the alignment film 122, after the first layer 122L1 and the second layer 122L2 are formed, the weak rubbing treatment is performed on the surface layer of the alignment film 122; therefore, even if a region of the alignment film cissing portion 122a appears during the formation of the alignment film 122, an alignment state is formed by the rubbing treatment on the surface of the first layer 122L1 remaining in the region of the alignment film cissing portion 122a. Accordingly, the effect of suppressing occurrence of a faint bright spot defect is obtained.
Hereinafter, the effect of suppressing the occurrence of a faint bright spot defect due to the alignment film on which both the weak rubbing treatment and the photo-alignment treatment are used in combination will be described using a comparative example.
As illustrated in
Meanwhile, in the case of an alignment film in which the weak rubbing treatment and the photo-alignment treatment are used in combination, for the alignment film for photo-alignment used in Embodiment 1, as illustrated in
This is because, as described above, the alignment state is formed by the rubbing treatment on the first layer 122L1 remaining in the region where the alignment film cissing portion 122a occurs.
In addition, regarding the improvement of the resistance to a faint bright spot defect generated by an alignment film cissing portion, even when the alignment film 122 hardly remains due to the alignment film cissing portion 122a, it can be considered that the alignment state is formed even a little by performing the rubbing treatment on the surface layer of the OC layer 125 provided below the alignment film 122.
In the above, although the case where the alignment film cissing portion 122a appears in the alignment film 122 on the counter substrate 120 has been described, for the alignment film 112 on the array substrate 110, the weak rubbing treatment and the photo-alignment treatment are used in combination on the alignment film for photo-alignment; therefore, it is needless to say that the same effect is obtained in the case where the alignment film cissing portion appears on the alignment film 122.
As described above, in the liquid crystal display device 10a, for at least one of the alignment film 122 on the counter substrate 120 and the alignment film 112 on the array substrate 110, relatively weak rubbing treatment and the photo-alignment treatment have been used in combination on the alignment film for photo-alignment. Accordingly, even in the area where alignment film cissing portion has appeared, it becomes an area with an alignment state due to the weak rubbing treatment, and as a result, resistance to faint bright spot defects caused by the alignment film cissing portion is improved.
In the above, a description has been given of a faint bright spot defect caused by the alignment film cissing portion, however, faint bright spot defects caused by minute foreign objects also occur due to the loss of parts of the photo-alignment film in the region where the minute foreign objects has appeared. For this reason, in the liquid crystal display device 10a, the effect of improving the resistance to the faint bright spot defect can be obtained as in the same with the case of the faint bright spot defect caused by the alignment film cissing portions.
Also, in the liquid crystal display device 10a, for at least one of the alignment film 122 on the counter substrate 120 and the alignment film 112 on the array substrate 110, relatively weak rubbing treatment and the photo-alignment treatment are used in combination on the alignment film for photo-alignment. Alignment scratches and alignment defects due to the rubbing treatment are unlikely to be caused. In addition, even if alignment scratches and alignment defects occur, as long as the alignment scratches or the alignment defects are minor, the alignment scratches and alignment defects are not visibly recognized as alignment defects in the display area 200 since an alignment regulation force is given by a photo-alignment treatment performed after the rubbing treatment. In other words, the effect that almost no troubles associated with the general rubbing treatment occur is also obtained.
<Modification>
Subsequently, as a modification of Embodiment 1, as a configuration for adjusting the viewing angle direction, a description will be given of pretilt angle setting and an arrangement relationship of the optical axes of each optical film in a configuration in which a retardation plate is added in addition to optical films such as polarizing plates 141 and 142 arranged on the main surface of the liquid crystal panel 100.
<Modification 1>
In
That is, as illustrated in
Also, as illustrated in
Further, the slow axis of the biaxial retardation plate 150 is set in the 90-degree direction, that is, the direction parallel to the Y-axis direction. Also, for the arrangement relationship between the alignment direction of the liquid crystal molecules and the optical axes of the polarizing plates, the absorption axis of the polarizing plate 141 on the incident side of the backlight BL is parallel to the alignment direction (Y-axis direction) of the liquid crystal molecules LC and the absorption axis of the polarizing plate 142 on the display region 200 side is set in a direction perpendicular to the alignment direction of the liquid crystal molecules LC. Further, the slow axis of the biaxial retardation plate 150 is set in a direction parallel to the alignment direction (Y-axis direction) of the liquid crystal molecules LC.
By introducing the optical design described above, also in the liquid crystal display device 10A of Modification 1, similar to the liquid crystal display device 10 of Embodiment 1, the direction which is slightly higher with respect to the display area 200, that is, the direction that maximizes the contrast when viewed from the +Y direction side slightly in the +Z direction, that is, the optimal viewing angle direction is set, by utilizing the minute pretilt angle. The viewing angle optimized when viewed from a slightly upper side with respect to the display area 200 is particularly suitable for a liquid crystal display device for in-vehicle use. Further, the addition of the biaxial retardation plate 150 further increases the contrast when viewed from an oblique direction.
<Modification 2>
In
That is, as illustrated in
Also, as illustrated in
Further, the slow axis of the biaxial retardation plate 160 is set in the 90-degree direction along with the retardation layer 161 and the retardation layer 162, that is, the direction parallel to the Y-axis direction. Also, for the arrangement relationship between the alignment direction of the liquid crystal molecules and the optical axes of the polarizing plates, the absorption axis of the polarizing plate 141 on the incident side of the backlight BL is parallel to the alignment direction (Y-axis direction) of the liquid crystal molecules LC and the absorption axis of the polarizing plate 142 on the display region 200 side is set in a direction perpendicular to the alignment direction of the liquid crystal molecules LC. Further, the slow axis of the biaxial retardation plate 160 is set in a direction parallel to the alignment direction (Y-axis direction) of the liquid crystal molecules LC.
By introducing the optical design described above, also in the liquid crystal display device 10B of Modification 2, similar to the liquid crystal display device 10 of Embodiment 1, the direction which is slightly higher with respect to the display area 200, that is, the direction that maximizes the contrast when viewed from the +Y direction side slightly in the +Z direction, that is, the optimal viewing angle direction is set, by utilizing the minute pretilt angle. The viewing angle optimized when viewed from a slightly upper side with respect to the display area 200 is particularly suitable for a liquid crystal display device for in-vehicle use. Further, the addition of the biaxial retardation plate 160 further increases the contrast when viewed from an oblique direction.
It should be noted that Embodiment of the present invention can be arbitrarily combined and can be appropriately modified or omitted without departing from the scope of the invention.
While the invention has been shown and described in detail, the foregoing description is in all aspects illustrative and not restrictive. It is therefore understood that numerous modifications and variations can be devised without departing from the scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-109645 | Jun 2019 | JP | national |
