KR102049739B1 - Liquid Crystal Display Device And Method of Fabricating The Same - Google Patents

Abstract

This invention makes it a subject to obtain the liquid crystal display device and the manufacturing method of a liquid crystal display device which can improve the brightness and viewing angle characteristic of a liquid crystal display.
The 1st board | substrate and 2nd board | substrate which oppose through a liquid crystal layer, the 1st alignment film which orientates the liquid crystal molecule of the 1st board | substrate side of a liquid crystal layer, and the 2nd alignment film which orientates the liquid crystal molecule of the 2nd board | substrate side of a liquid crystal layer. And a first polarizing plate provided on the first substrate and having a first absorption axis, and a second polarizing plate provided on the second substrate and having a second absorption axis orthogonal to the first absorption axis, wherein the anchoring energy of the first alignment layer is It is smaller than the anchoring energy of a 2nd alignment film, and the absorption axis direction of a 1st polarizing plate is parallel with the orientation direction of a 1st alignment film and a 2nd alignment film.

Description

Liquid crystal display device and method of manufacturing the liquid crystal display device {Liquid Crystal Display Device And Method of Fabricating The Same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a method for manufacturing the liquid crystal display device which generate an electric field parallel to the liquid crystal panel surface to control the display.

As a display method of a liquid crystal panel, an In-Plane Switching (IPS) method of controlling display by applying a voltage to an electrode provided on a glass substrate to generate an electric field parallel to the liquid crystal layer is known. In the IPS system, since the apparent length (refractive index ellipsoid) of the liquid crystal molecules becomes substantially constant regardless of the viewing angle direction of the liquid crystal panel, the viewing angle characteristic is excellent.

However, in the IPS method, since the transverse component of the electric field for generating an electric field becomes relatively small directly above the electrode, the operability of the liquid crystal molecules directly above the electrode is lowered, and the brightness when the voltage of the electrode is turned on (white display) There is a shortage of tasks.

In order to solve such a subject, for example, in patent document 1, the anchoring energy of the alignment film which orientates a liquid crystal molecule is made small, and the orientation regulation force of a liquid crystal molecule is weakened. As a result, even when the transverse component of the electric field is small, the liquid crystal molecules on the electrode-forming substrate easily operate in response to the transverse electric field, so that sufficient brightness can be obtained directly on the electrode.

Patent Document 1: Japanese Patent Publication No. 2009-271390

The anchoring energy of the liquid crystal panel alignment layer provides a restoring force to align the alignment direction of the liquid crystal molecules in a constant direction when the voltage of the electrode is OFF (black display). In patent document 1, restoring force is made small by making anchoring energy small, and it is easy to operate a liquid crystal molecule. However, when the anchoring energy magnitude is changed in the liquid crystal layer, the alignment characteristics of the liquid crystal molecules also change in the liquid crystal layer. Therefore, although the brightness of the liquid crystal display is improved, there is a possibility that the viewing angle characteristic, which is a characteristic of the IPS method, may be affected.

Patent Document 1 does not mention any effect on the viewing angle characteristic by reducing the anchoring energy of the alignment film. Therefore, the applicant examined the influence on the viewing angle characteristic when the anchoring energy of the liquid crystal panel alignment film was made small.

The liquid crystal display device which concerns on this invention is a 1st board | substrate and a 2nd board | substrate which oppose through a liquid crystal layer, the 1st alignment film which orientates the liquid crystal molecule on the 1st board | substrate side of a liquid crystal layer to a 1st direction, and a liquid crystal layer of A second alignment film for orienting the liquid crystal molecules on the second substrate side in the first direction, a first polarizing plate provided on the first substrate and having a first absorption axis, and a second provided on the second substrate and orthogonal to the first absorption axis A liquid crystal display device comprising a second polarizing plate having an absorption axis and controlling a display by applying a voltage to an electrode provided on a first substrate to generate an electric field parallel to the liquid crystal layer, wherein the anchoring energy of the first alignment layer is the second. It is smaller than the anchoring energy of an oriented film, and the absorption axis direction of a 1st polarizing plate is parallel to a 1st direction, It is characterized by the above-mentioned.

In addition, the method for manufacturing a liquid crystal display device according to the present invention includes a first substrate and a second substrate facing each other via a liquid crystal layer, and applies a voltage to an electrode provided on the first substrate to form an electric field parallel to the liquid crystal layer. A method of manufacturing a liquid crystal display device that controls display by generating a step, comprising: providing a first alignment layer for orienting liquid crystal molecules on a first substrate side of a liquid crystal layer in a first direction by a relatively small anchoring energy; Providing a second alignment film for orienting the second substrate-side liquid crystal molecules in the first direction by a relatively large anchoring energy; and installing the first polarizing plate on the first substrate so that the absorption axis direction is parallel to the first direction. And providing a second polarizing plate on the second substrate such that the absorption axis direction is perpendicular to the first direction.

According to this invention, the liquid crystal display device and the manufacturing method of a liquid crystal display device which can improve the brightness and viewing angle characteristic of a liquid crystal display can be obtained.

1 is a schematic diagram showing the configuration of a liquid crystal display device according to a first embodiment.
FIG. 2 is a diagram showing light transmission characteristics of the liquid crystal display device according to the first embodiment.
3 is a diagram illustrating viewing angle characteristics of the liquid crystal display device according to the first embodiment.
4 is a schematic diagram showing the configuration of a liquid crystal display device according to a second embodiment.
FIG. 5 is a diagram showing light transmission characteristics of the liquid crystal display device according to the second embodiment.
6 is a diagram illustrating viewing angle characteristics of the liquid crystal display device according to the second embodiment.
FIG. 7 is a diagram showing light transmission characteristics of the liquid crystal display device according to the third embodiment. FIG.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described with reference to drawings. In addition, this invention is not limited to the following embodiment, It can change suitably in the range which does not deviate from the summary. In addition, in the figure demonstrated below, what has the same function may attach | subject the same code | symbol, and may abbreviate | omit or simplify the description.

<1st embodiment>

The liquid crystal display device according to the first embodiment will be described with reference to FIGS. 1 to 3. 1 is a schematic diagram showing the configuration of a liquid crystal display device according to a first embodiment. FIG. 1A schematically illustrates a cross section of a liquid crystal display, and FIG. 1B schematically illustrates alignment of liquid crystal molecules in a plane of the liquid crystal layer 11 of the liquid crystal display. (A) is sectional drawing along the AA 'line shown to FIG. 1 (b).

The liquid crystal display device shown in FIG. 1A includes a liquid crystal panel 1 and a backlight unit 2. A light diffusion sheet, a prism sheet, or the like may be disposed between the liquid crystal panel 1 and the backlight unit 2.

The liquid crystal panel 1 has a pair of glass substrates 12a and 12b which face each other via the liquid crystal layer 11. A plurality of electrodes 10 are provided on the glass substrate 12a on the backlight unit 2 side among the glass substrates 12a and 12b. The control unit (not shown) of the liquid crystal display device applies a voltage between the electrodes 10 of the glass substrate 12a to generate an electric field parallel to the surface of the liquid crystal layer 11, and generates liquid crystal molecules into the liquid crystal layer 11. The display of the liquid crystal display device is controlled by rotating in the plane.

The polarizing plates 14a and 14b are respectively provided in the liquid crystal panel 1 so that the glass substrates 12a and 12b may be inserted from the outside. The polarization axis directions of the polarizing plates 14a and 14b are arranged so that light illuminated from the backlight unit 2 passes or is blocked when a voltage is applied to the electrode 10. For example, in the embodiment shown in FIG. 1A, the polarization axis directions of the polarizing plates 14a and 14b are perpendicular to each other, and illumination light from the backlight unit 2 passes when a voltage is applied to the electrode 10. do.

Alignment films 13a and 13b are provided between the glass substrates 12a and 12b and the liquid crystal layer 11 of the liquid crystal panel 1, respectively. The alignment films 13a and 13b align liquid crystal molecules of the liquid crystal layer 11 in a predetermined direction when the voltage of the electrode 10 is turned off. Moreover, the color filter 15 is provided between the glass substrate 12b and the alignment film 13b of the liquid crystal panel 1. The color filter 15 allows light of the three primary color wavelength ranges of R (red) / G (green) / B (blue) of the light illuminated from the backlight unit 2 to pass.

The backlight unit 2 is an edge light type backlight and includes an LED light source 22 having an LED element at an end of the light guide plate 21. The LED light source 22 supplies light for illuminating the liquid crystal panel 1 through the light guide plate 21.

The liquid crystal panel 1 of this embodiment shown in FIG. 1 generates a transverse electric field parallel to the liquid crystal layer 11, and rotates the liquid crystal molecules in the liquid crystal layer 11 plane to control the display (IPS). mode, AH-IPS mode). However, as described above, in the IPS method, since the transverse component of the electric field becomes relatively small directly above the electrode 10, the liquid crystal molecules directly above the electrode 10 are difficult to respond to the transverse electric field, and the brightness in the white display is insufficient. .

Therefore, in this embodiment, as shown to Fig.1 (a), the anchoring energy of the alignment film 13a is made small, and the orientation control force of the liquid crystal molecule of the glass substrate 12a side is weakened. As a result, even when the transverse component of the electric field is small, the liquid crystal molecules on the glass substrate 12a side easily operate in response to the transverse electric field, so that sufficient brightness can be ensured even directly on the electrode 10.

Next, the manufacturing method of the liquid crystal display device of this embodiment shown in FIG. 1 is demonstrated. First, a negative nematic liquid crystal material (dielectric anisotropy Δε = 10, refractive index anisotropy Δn = 0.100) is enclosed between a pair of opposing glass substrates 12a and 12b to form a liquid crystal layer 11. Formed. The thickness of the glass substrates 12a and 12b was 0.5 mm, respectively, and the thickness of the liquid crystal layer 11 was 3.4 micrometers.

Between the glass substrate 12b and the liquid crystal layer 11, the color filter 15 which permeate | transmits light of the three primary color wavelength ranges of R (red) / G (green) / B (blue) was formed. On the other hand, between the glass substrate 12a and the liquid crystal layer 11, the linear electrode 10 for generating the electric field parallel to the liquid crystal layer 11 was formed. The electrode 10 has a configuration in which the pixel electrode and the common electrode are alternately arranged, and a voltage is applied between the pixel electrode and the common electrode, and the width of the electrode 10 is 3 μm and the interval of the electrode 10 is 10 μm. I did it.

In addition, an alignment film 13a was formed between the glass substrate 12a and the liquid crystal layer 11, and an alignment film 13b was formed between the glass substrate 12b and the liquid crystal layer 11. The anchoring energy of the alignment film 13a was relatively small at 10 ⁻⁷ J / m ² , and the anchoring energy of the alignment film 13b was relatively large at 10 ⁻² J / m ² . Moreover, the orientation film 13a and the orientation film 13b were orientated substantially in the same direction, and it was set as homogeneous orientation in which all the liquid crystal molecules of the liquid crystal layer 11 are orientated in substantially the same direction at the time of voltage OFF.

At this time, the anchoring energy of the alignment film 13a was made smaller than the anchoring energy of the alignment film 13b in the following order. First, a polyimide film having an anchoring energy of 10 ⁻² J / m ² was formed on the glass substrate 12a. Then, the polyimide film was rubbed, so that the liquid crystal molecules of the liquid crystal layer 11 were uniformly oriented at an angle α = about 20 degrees with respect to the long axis direction of the linear electrode 10 as shown in FIG. . Subsequently, UV light was irradiated to the polyimide film to about 1000 mJ / m <^2> by mask exposure, and the anchoring energy of the alignment film 13a was made into 10 ^-7 J / m <^2> .

Thereafter, the polarizing plates 14a and 14b were disposed to sandwich the glass substrates 12a and 12b. In the polarizing plates 14a and 14b, typically, one of the polarizing plates 14a and 14b has an absorption axis parallel to the liquid crystal molecule alignment direction of the liquid crystal layer 11, and the other absorption axis is a liquid crystal molecule of the liquid crystal layer 11. It is arranged to be orthogonal to the orientation direction. In this embodiment, as shown to FIG. 1 (b), the absorption axis direction 18 of the polarizing plate 14a was made to be parallel with the liquid crystal molecule orientation direction of the liquid crystal layer 11. And the backlight unit 2 provided with the white LED light source 22 in the light guide plate 21 edge part was arrange | positioned at the back side of the liquid crystal panel 1.

FIG. 2 is a diagram showing light transmission characteristics of the liquid crystal display device according to the first embodiment. FIG. 2 shows the light transmittance (%) measured value of the liquid crystal panel 1 when a voltage difference of 0 to 10 V is applied between adjacent electrodes 10. The light transmission characteristic (T1) of the liquid crystal panel 1 of this embodiment was measured by making small (weak) anchoring energy to ^10-7 J / m <^2> in the whole alignment film 13a. The conventional light transmission characteristic (T2), the alignment layer (13a) was high (strongly) measured by the anchoring energy at the global to 10 ^-2 J / m ^2. In addition, the anchoring energy of the alignment film 13b was large (strongly) at 10 ⁻² J / m ² throughout the entire light transmission characteristic (T1, T2) measurement.

As shown in FIG. 2, the light transmission characteristic T1 of the liquid crystal panel 1 of this embodiment was improved significantly compared with the light transmission characteristic T2 of the conventional liquid crystal panel. It is thought that this is because the liquid crystal molecules directly above the electrode 10 become easier to respond to the transverse electric field by reducing the anchoring energy of the alignment film 13a.

Next, the viewing angle characteristic at the time of making anchoring energy of the alignment film 13a of the liquid crystal panel 1 small is examined. In the structure shown in FIG. 1 in which the anchoring energy of the alignment film 13a is made relatively small, the orientation characteristic of the liquid crystal layer 11 becomes asymmetrical on the polarizing plate 14a side and the polarizing plate 14b side. Therefore, the absorption axis direction of the polarizing plate 14a is made parallel to the liquid crystal molecule alignment direction of the liquid crystal layer 11, and the absorption axis direction of the polarizing plate 14a is made perpendicular to the liquid crystal molecule alignment direction of the liquid crystal layer 11. In this case, there is a possibility that the viewing angle characteristic of the liquid crystal display device is different. Therefore, the applicant measured the viewing angle characteristic by making the anchoring energy of the alignment film 13a of the liquid crystal panel 1 small, and changing the absorption axis direction of the polarizing plate 14a with respect to the liquid crystal molecular alignment direction.

3 is a diagram illustrating viewing angle characteristics of the liquid crystal display device according to the first embodiment. 3 shows contrast ratios when the electrode 10 voltage is turned on (white display) and when the voltage is turned off (black display) in a viewing angle range of 0 to 360 degrees azimuth and 0 to 90 degrees polar angle. The measured actual value is shown.

3 (a) and 3 (b) show the viewing angle characteristic measurement results when the anchoring energy of the alignment film 13a is made relatively small in FIGS. 3 (a) to 3 (d). FIG. 3A shows the viewing angle characteristic C1 of the liquid crystal panel 1 of the present embodiment in which the absorption axis direction of the polarizing plate 14a is parallel to the liquid crystal molecular alignment direction, and FIG. 3B shows the polarizing plate 14a. The viewing angle characteristic C2 when the absorption axis direction is perpendicular to the liquid crystal molecule alignment direction is shown.

3 (c) and 3 (d) show results of measuring viewing angle characteristics of a conventional liquid crystal panel in which the anchoring energy of the alignment film 13a is increased. FIG. 3C shows the viewing angle characteristic C3 when the absorption axis direction of the polarizing plate 14a is made parallel to the liquid crystal molecule alignment direction, and FIG. 3D shows that the absorption axis direction of the polarizing plate 14a is aligned with the liquid crystal molecule. The viewing angle characteristic C4 when it is perpendicular to the direction is shown. 3A to 3D, the absorption axis of the polarizing plate 14a and the absorption axis of the polarizing plate 14b are perpendicular to each other.

In the viewing angle characteristics C1 and C2 shown in FIG. 3, the area | region with contrast ratio C / R = 1000 or more is larger than viewing angle characteristics C3 and C4. That is, it can be seen that the viewing angle characteristics C1 and C2 of the liquid crystal panel 1 in which the anchoring energy of the alignment film 13a is reduced are superior to the viewing angle characteristics C3 and C4 of the conventional liquid crystal panel. This is considered to be because the brightness at the time of voltage ON (white display) of the liquid crystal panel 1 is improved and the contrast ratio C / R is improved.

In addition, in the viewing angle characteristic C1 shown in FIG. 3, the area | region with contrast ratio C / R = 10 or less is smaller than viewing angle characteristic C2. That is, the viewing angle characteristic C1 of the liquid crystal panel 1 of this embodiment which made the absorption axis direction of the polarizing plate 14a parallel to the liquid crystal molecule orientation direction made the absorption axis direction of the polarizing plate 14a perpendicular to the liquid crystal molecule orientation direction. It turns out that it is superior to the viewing angle characteristic C2 in the case. This is because the liquid crystal alignment in the white display becomes asymmetrical on the polarizing plate 14a side and the polarizing plate 14b side because only the anchoring energy of the alignment film 13a side is relatively small, and a difference occurs in the viewing angle characteristic C1 and the viewing angle characteristic C2. I think.

Thus, in the structure of the liquid crystal panel 1 which made the anchoring energy of the alignment film 13a shown to FIG. 1 (a) small, the absorption axis of the polarizing plate 14a is shown in FIG. It was found that the arrangement in parallel improved the viewing angle characteristic. On the other hand, in the conventional structure in which the anchoring energy is made the same in the alignment film 13a and the alignment film 13b, the absorption angle of the polarizing plate 14a is perpendicular to the viewing angle characteristic C3 in which the liquid crystal molecule alignment "?" Is parallel to the liquid crystal molecule alignment direction. Little difference was seen in one viewing angle characteristic C4.

As described above, in the liquid crystal display device of the present embodiment, the anchoring energy of the first alignment film (alignment film, 13a) is smaller than the anchoring energy of the second alignment film (alignment film, 13b). And the absorption axis direction of a 1st polarizing plate (polarizing plate, 14a) is made parallel to the orientation direction of a 1st alignment film and a 2nd alignment film. Thereby, the liquid crystal display device and the manufacturing method of a liquid crystal display device which can improve the brightness and viewing angle characteristic of a liquid crystal display can be obtained. In addition, since the liquid crystal molecules directly on the electrodes become more responsive, the electric field applied between the electrodes can be further reduced, and the power consumption of the liquid crystal display device can be reduced.

In addition, in the above description, although the some electrode 10 was formed in the same wiring layer, you may form a pixel electrode and a common electrode separately in the other wiring layer insulated from each other by insulating films, such as SiNx and SiOx.

In addition, in this embodiment, although the indium zinc oxide (IZO) which has a high light transmittance T of 85% was employ | adopted as a main material of the electrode 10, it is not limited to this. The electrode 10 may be a conductor film having a high light transmittance. Instead of IZO, it is possible to use for example ITO (indium tin oxide, T = 88%), AZO (aluminum doped zinc oxide, T = 92%). Alternatively, GZO (gallium doped zinc oxide, T = 92%) or ATO (antimony tin oxide, T = 87%) may be used.

<2nd embodiment>

Next, the liquid crystal display device which concerns on 2nd Embodiment is demonstrated with reference to FIGS. 4 is a schematic diagram showing the configuration of a liquid crystal display device according to a second embodiment. FIG. 4A schematically illustrates a cross section of the liquid crystal display, and FIG. 4B schematically illustrates alignment of liquid crystal molecules in the plane of the liquid crystal layer 11 of the liquid crystal display. (A) is sectional drawing along the AA 'line shown to FIG. 4 (b). The structure of the electrode 10 mainly differs from the liquid crystal display device of 1st Embodiment shown in FIG. 1 in the liquid crystal display device shown in FIG. In addition, in the case of the liquid crystal panel 1 of the IPS system, the material and the thickness of the liquid crystal layer 11 are changed to show that the effect of the present invention can be obtained regardless of other configurations. Hereinafter, the structure different from 1st Embodiment is demonstrated.

In the first embodiment described above, as shown in FIG. 1, a plurality of linear electrodes 10 were formed in the wiring layer between the glass substrate 12a and the liquid crystal layer 11. In contrast, in the liquid crystal display device of the present embodiment, as shown in FIG. 4, only a plurality of linear pixel electrodes 10a are formed in the first wiring layer between the glass substrate 12a and the liquid crystal layer 11, and the first The rectangular common electrode 10b was formed in the 2nd wiring layer different from the wiring layer. The display was controlled by applying a voltage between the pixel electrode 10a and the common electrode 10b. As a result, in this embodiment, as the pixel electrode 10a approaches the pixel electrode 10a as shown in FIG. 4 (a), the distance to the common electrode 10b becomes shorter and the electric field becomes stronger. Therefore, the liquid crystal molecules near the pixel electrode 10a The operability can be further improved. Hereinafter, the manufacturing method of the liquid crystal display device of this embodiment shown in FIG. 4 is demonstrated.

First, a nematic liquid crystal material having a negative dielectric anisotropy (dielectric anisotropy Δε = -3, refractive index anisotropy Δn = 0.100) is enclosed between a pair of opposing glass substrates 12a and 12b, and the liquid crystal layer 11 Formed). The thickness of the glass substrates 12a and 12b was 0.5 mm, respectively, and the thickness of the liquid crystal layer 11 was 4.2 micrometer. Since the nematic liquid crystal material having negative dielectric anisotropy has few kinds, the degree of freedom of liquid crystal material selection is reduced. However, by using the nematic liquid crystal material having negative dielectric anisotropy, the operability of the liquid crystal with respect to the liquid crystal molecular field can be improved.

Between the glass substrate 12b and the liquid crystal layer 11, the color filter 15 which permeate | transmits light of the three primary color wavelength ranges of R (red) / G (green) / B (blue) was formed. On the other hand, a linear pixel electrode 10a was formed in the first wiring layer between the glass substrate 12a and the liquid crystal layer 11. And the rectangular common electrode 10b was formed in the 2nd wiring layer different from the 1st wiring layer. The width of the pixel electrode 10a was 2 μm, and the interval between the pixel electrodes 10a was 4 μm. An insulating layer 16 made of a 3000 nm thick SiNx film was formed between the first wiring layer and the second wiring layer. As shown in FIG. 4, the pixel electrode 10a and the common electrode 10b have overlapping regions when the plane is viewed from a direction perpendicular to the surface of the glass substrate 12a.

In addition, an alignment film 13a was formed between the glass substrate 12a and the liquid crystal layer 11, and an alignment film 13b was formed between the glass substrate 12b and the liquid crystal layer 11. The anchoring energy of the alignment film 13a was relatively small at 10 ⁻⁶ J / m ² , and the anchoring energy of the alignment film 13b was relatively large at 10 ³ J / m ² . Moreover, the orientation film 13a and the orientation film 13b were orientated substantially in the same direction, and it was set as homogeneous orientation in which all the liquid crystal molecules of the liquid crystal layer 11 are orientated in substantially the same direction at the time of voltage OFF.

At this time, the anchoring energy of the alignment film 13a was made smaller than the anchoring energy of the alignment film 13b in the following order. First, the polymer brush with small anchoring energy was formed in the glass substrate 12a. After that, the entire polymer brush is rubbed, and as shown in FIG. 4 (b), the liquid crystal molecules of the liquid crystal layer 11 are uniformly angled at approximately 83 degrees with respect to the long axis direction of the linear pixel electrode 10a. Orientated.

Thereafter, the polarizing plates 14a and 14b were disposed to sandwich the glass substrates 12a and 12b. In this embodiment, as shown in FIG.4 (b), the absorption axis direction 18 of the polarizing plate 14a was made to be parallel to the liquid crystal molecule orientation direction of the liquid crystal layer 11. As shown in FIG. And the backlight unit 2 provided with the white LED light source 22 in the light guide plate 21 edge part was arrange | positioned at the back side of the liquid crystal panel 1.

FIG. 5 is a diagram showing light transmission characteristics of the liquid crystal display device according to the second embodiment. 6 is a view showing viewing angle characteristics of the liquid crystal display device according to the second embodiment. The measurement in the liquid crystal display device of this embodiment shown in FIG. 5 and FIG. 6 was performed on the same method and the same conditions fundamentally with the measurement in the liquid crystal display device of 1st embodiment shown in FIG. 2 and FIG. .

As shown in FIG. 5 and FIG. 6, it is understood that the light transmission characteristics T1 and the viewing angle characteristics C1 of the liquid crystal panel 1 of the present embodiment are further improved than the first embodiment shown in FIGS. 2 and 3. This is considered to be because the operability of the liquid crystal molecules near the pixel electrode 10a is further improved by improving the structure of the electrode 10.

In addition, it can be seen that the viewing angle characteristic C1 of the liquid crystal panel 1 of the present embodiment shown in FIG. 6 is the largest in the region having a contrast ratio C / R = 1000 or more and the smallest in the region having a contrast ratio C / R = 10 or less. . That is, also in this embodiment, it turns out that the viewing angle characteristic C1 which made the anchoring energy of the alignment film 13a small, and made the absorption axis of the polarizing plate 14a parallel to the liquid crystal molecule orientation direction is superior to other viewing angle characteristics C2-C4. In such a configuration in which the anchoring energy of the alignment film 13a is reduced, the viewing angle characteristic is improved by arranging the absorption axis of the polarizing plate 14a in parallel with the liquid crystal alignment direction as shown in FIG. I found out.

As mentioned above, in the liquid crystal display device of this embodiment, a voltage is applied between the linear pixel electrode provided in the 1st wiring layer of a 1st glass substrate, and the rectangular common electrode provided in the 2nd wiring layer different from a 1st wiring layer. Display is controlled. Thereby, the liquid crystal display device and the manufacturing method of a liquid crystal display device which can further improve the brightness and viewing angle characteristic of a liquid crystal display can be obtained.

In this embodiment, although ITO (indium tin oxide) having a high light transmittance (T) of 88% is employed as the main materials of the pixel electrode 10a and the common electrode 10b, the present invention is not limited thereto. The pixel electrode 10a and the common electrode 10b may be a conductor film having a high light transmittance. Instead of ITO, it is possible to use, for example, indium zinc oxide (T = 85%), aluminum doped zinc oxide (T = 92%). Alternatively, GZO (gallium doped zinc oxide, T = 92%) or ATO (antimony tin oxide, T = 87%) may be used.

Third Embodiment

In this embodiment, the influence of the anchoring energy magnitude on the light transmission characteristic of the liquid crystal panel 1 is examined. The configuration of the liquid crystal display device of the present embodiment is basically the same as that of the second embodiment shown in FIG. 4. However, in the case of the liquid crystal panel 1 of the IPS system, the material and the thickness of the liquid crystal layer 11 are changed in order to show that the effect of the present invention can be obtained regardless of other configurations. Hereinafter, the part different from 2nd Embodiment is demonstrated.

First, a negative nematic liquid crystal material (dielectric anisotropy Δε = 10, refractive index anisotropy Δn = 0.100) is enclosed between a pair of opposing glass substrates 12a and 12b to form a liquid crystal layer 11. Formed. The thickness of the glass substrates 12a and 12b was 0.5 mm, respectively, and the thickness of the liquid crystal layer 11 was 4.4 micrometers.

Between the glass substrate 12b and the liquid crystal layer 11, the color filter 15 which permeate | transmits light of the three primary color wavelength ranges of R (red) / G (green) / B (blue) was formed. On the other hand, a linear pixel electrode 10a was formed in the first wiring layer between the glass substrate 12a and the liquid crystal layer 11. And the rectangular common electrode 10b was formed in the 2nd wiring layer different from a 1st wiring layer. The width of the pixel electrode 10a was 2 μm, and the interval between the pixel electrodes 10a was 4 μm. An insulating layer 16 made of a 3000 nm thick SiNx film was formed between the first wiring layer and the second wiring layer. As shown in FIG. 4, the pixel electrode 10a and the common electrode 10b have overlapping regions when the plane is viewed from a direction perpendicular to the surface of the glass substrate 12a.

In addition, an alignment film 13a was formed between the glass substrate 12a and the liquid crystal layer 11, and an alignment film 13b was formed between the glass substrate 12b and the liquid crystal layer 11. The anchoring energy of the alignment film 13a is relatively small, 10 ⁻⁸ to 10 ⁻¹ J / m ² , and the anchoring energy of the alignment film 13b is 10 ^3. It was relatively large as J / m ² . Moreover, the orientation film 13a and the orientation film 13b were orientated substantially in the same direction, and it was set as homogeneous orientation in which all the liquid crystal molecules of the liquid crystal layer 11 are orientated in substantially the same direction at the time of voltage OFF.

At this time, the anchoring energy of the alignment film 13a was made smaller than the anchoring energy of the alignment film 13b in the following order. First, a polymer brush with small anchoring energy was formed in the alignment film 13a. After that, the entire polymer brush is rubbed, and as shown in FIG. 4 (b), the liquid crystal molecules of the liquid crystal layer 11 are uniformly angled at approximately 83 degrees with respect to the long axis direction of the linear pixel electrode 10a. Orientated.

Thereafter, the polarizing plates 14a and 14b were disposed to sandwich the glass substrates 12a and 12b. In this embodiment, as shown in FIG.4 (b), the absorption axis direction 18 of the polarizing plate 14a was made to be parallel to the liquid crystal molecule orientation direction of the liquid crystal layer 11. As shown in FIG. And the backlight unit 2 provided with the white LED light source 22 in the light guide plate 21 edge part was arrange | positioned at the back side of the liquid crystal panel 1.

FIG. 7 is a diagram showing light transmission characteristics of the liquid crystal display device according to the third embodiment. FIG. FIG. 7 shows the light transmittance (%) measured value of the liquid crystal panel 1 when a voltage difference of 0 to 10 V is applied between the pixel electrode 10a and the common electrode 10b. In FIG. 7, the liquid crystal when the anchoring energy of the alignment layer 13a is 10 ⁻⁸ , 10 ⁻⁷ , 10 ⁻⁶ , 10 ⁻⁵ , 10 ⁻⁴ , 10 ⁻³ , 10 ^−2, and 10 ⁻¹ J / m ² The light transmission characteristic of the panel 1 was measured.

As shown in FIG. 7, when the anchoring energy of the alignment film 13a is set to 10 ⁻³ J / m ² or more, the light transmission characteristic according to the liquid crystal display device of the present embodiment is conventional light with the anchoring energy increased throughout. It was generally the same as the transmission characteristic. Next, when the anchoring energy of the alignment film 13a is 10 ⁻⁴ or less, the light transmittance is improved as the anchoring energy is reduced. However, even if the anchoring energy of the alignment film 13a was reduced to 10 ⁻⁶ J / m ² or less, the light transmittance did not improve further. In this way, it can be seen that when the anchoring energy of the alignment layer 13a is 10 ⁻⁶ J / m ² or less, the liquid crystal display brightness can be greatly improved.

As described above, in the liquid crystal display device of the present embodiment, the brightness of the liquid crystal display can be greatly improved by setting the anchoring energy of the first alignment layer to 10 ⁻⁶ J / m ² or less. In addition, when the anchoring energy is 10 ⁻⁶ J / m ² or less, since the light transmittance hardly changes, the influence of the change caused by the variation of the anchoring energy on the light transmission characteristics can be suppressed. This makes it possible to obtain a liquid crystal display device in which display unevenness is less likely to occur and the manufacturing margin is wide.

<Other Embodiments>

All the above-mentioned embodiments only showed the example embodied in implementing this invention, and the technical scope of this invention should not be interpreted limitedly by these. That is, the present invention can be implemented in various forms without departing from the spirit or the main features thereof.

For example, in the above-described embodiment, only the anchoring energy directly above the electrode 10 of the alignment film 13a or the pixel electrode 10a may be relatively small. That is, by maintaining the anchoring energy in the region other than just above the electrode 10 of the alignment film 13a, the liquid crystal molecular restoring force at the time of the voltage OFF of the electrode 10 is hardly reduced, and the responsiveness of the liquid crystal display is reduced. It can be suppressed. That is, the brightness and responsiveness of the liquid crystal display can be compatible.

In order to make anchoring energy of the alignment film 13a relatively small only directly above the electrode 10, for example, the alignment film 13a is formed in the following order. First, a polyimide film having an anchoring energy of 10 ⁻² J / m ² is formed on the glass substrate 12a. Then, the polyimide film is subjected to a rubbing treatment so that the liquid crystal molecular alignment direction of the liquid crystal layer 11 is uniformly aligned at a predetermined angle α with respect to the major axis direction of the linear electrode 10. Subsequently, by UV exposure, only 1000 mJ / m <^{2> of} UV light was irradiated only to the polyimide film | membrane immediately above the electrode 10 by mask exposure, and the anchoring energy directly on the electrode 10 was made small at 10 <^-7> J / m <^2> .

Alternatively, instead of irradiating UV directly on the electrode 10 of the alignment film 13a, a polymer brush with small anchoring energy may be formed in the region immediately above the electrode 10 of the alignment film 13a by using the photolithography method. Alternatively, a polymer brush having a small anchoring energy may be selectively formed in the region immediately above the electrode 10 of the alignment film 13a by the inkjet method.

In this way, the anchoring energy just above the electrode 10 of the alignment film 13a is smaller than the anchoring energy between the electrodes 10 of the alignment film 13a, thereby reducing the responsiveness of the liquid crystal display while reducing the brightness and viewing angle of the liquid crystal display. Properties can be improved.

1: liquid crystal panel 2: backlight unit
10: electrode 10a: pixel electrode
10b: common electrode 11: liquid crystal layer
12a, 12b: glass substrate 13a, 13b: alignment film
14a, 14b: polarizer

Claims (14)

A first substrate and a second substrate facing each other via a liquid crystal layer;
A first alignment film for orienting liquid crystal molecules on the first substrate side of the liquid crystal layer in a first direction,
A second alignment film for orienting liquid crystal molecules on the second substrate side of the liquid crystal layer in the first direction;
A first polarizing plate provided on the first substrate and having a first absorption axis;
A second polarizing plate provided on the second substrate and having a second absorption axis orthogonal to the first absorption axis,
A liquid crystal display device for controlling display by applying a voltage to an electrode provided on the first substrate to generate an electric field parallel to the liquid crystal layer.
The anchoring energy of the first alignment layer is smaller than the anchoring energy of the second alignment layer, and the anchoring energy of the first alignment layer is 10 ⁻¹¹ times or more and 10 ⁻⁴ times or less of the anchoring energy of the second alignment layer,
Liquid crystal display device wherein the absorption axis direction of the first polarizing plate is parallel to the first direction.
The method of claim 1,
And an anchoring energy directly on the electrode of the first alignment layer of 10 ⁻⁶ J / m ² or less.
The method according to claim 1 or 2,
The electrode is a linear pixel electrode provided in the first wiring layer of the first substrate, and the display is applied by applying a voltage between the pixel electrode and the rectangular common electrode provided in the second wiring layer different from the first wiring layer. Liquid crystal display device to control.
The method of claim 3, wherein
The pixel electrode and the common electrode have an overlapping area when viewed in a plane.
The method of claim 1,
A liquid crystal display device wherein the electrode is made of any one of ITO, IZO, AZO, GZO, and ATO.
The method of claim 1,
An anchoring energy directly on the electrode of the first alignment layer is smaller than the anchoring energy between the electrodes of the first alignment layer.
The method of claim 6,
A liquid crystal display device wherein the anchoring energy between the electrodes of the first alignment layer is the same as the anchoring energy of the second alignment layer.
Manufacture of a liquid crystal display device having a first substrate and a second substrate facing each other via a liquid crystal layer, and controlling a display by applying a voltage to an electrode provided on the first substrate to generate an electric field parallel to the liquid crystal layer. As a method,
Providing a first alignment layer for orienting the liquid crystal molecules on the first substrate side of the liquid crystal layer in a first direction by a relatively small anchoring energy;
Providing a second alignment layer to orient the liquid crystal molecules on the second substrate side of the liquid crystal layer in the first direction by a relatively large anchoring energy;
Providing a first polarizing plate on the first substrate such that an absorption axis direction is parallel to the first direction;
Providing a second polarizing plate on the second substrate such that an absorption axis direction is perpendicular to the first direction,
The anchoring energy of the first alignment layer is smaller than the anchoring energy of the second alignment layer, and the anchoring energy of the first alignment layer is 10 ⁻¹¹ times or more and 10 ⁻⁴ times or less of the anchoring energy of the second alignment layer. Way.
The method of claim 8,
The manufacturing method of the liquid crystal display device which further has the orientation step which makes anchoring energy just over the electrode of a said 1st alignment film smaller than anchoring energy between electrodes of a said 1st alignment film.
The method of claim 9,
The orientation step,
Forming a polyimide film on the first substrate;
A second step of rubbing the polyimide film;
And a third step of irradiating UV to a region immediately above the electrode of the polyimide film to make the anchoring energy just above the electrode of the polyimide film smaller than the anchoring energy between the electrodes of the polyimide film. The method of claim 8,
The first alignment layer is a manufacturing method of a liquid crystal display device comprising a polymer brush.
The method of claim 11,
And the first alignment layer comprises a polymer brush formed in a region directly above the electrode and a polyimide layer formed in a region other than directly above the electrode.
The method of claim 1,
The first alignment layer includes a polymer brush.
The method of claim 13,
The first alignment layer includes a polymer brush formed in a region directly above the electrode and a polyimide layer formed in a region other than directly above the electrode.

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