JP6924588B2 - Manufacturing method of liquid crystal display device and liquid crystal table device - Google Patents

Description

The present invention relates to a method for manufacturing a liquid crystal display device and a liquid crystal surface device.

As a display method for a liquid crystal panel, an IPS (In-Plane Switching) method is known in which a voltage is applied to an electrode formed on a glass substrate to form an electric field in a direction horizontal to the substrate surface to control the display. .. In the IPS system, the apparent length of the liquid crystal molecules (refractive index ellipsoid) is almost constant regardless of the viewing angle direction of the liquid crystal panel, so that the viewing angle characteristics are excellent.

In the liquid crystal panel, the orientation direction of the liquid crystal molecules is forced so that the liquid crystal molecules are oriented along a predetermined direction in a state where no electric field is applied. A rubbing method, a photo-alignment method, and the like are known as methods for forcing the orientation direction of liquid crystal molecules in an IPS liquid crystal panel. In the rubbing method, an alignment film made of polyimide or the like is formed on a substrate, and the surface of the alignment film is rubbed with a cloth. In the photo-alignment method, the surface of an alignment film made of a polyimide film or the like is irradiated with linearly polarized ultraviolet rays to give anisotropy to the surface of the alignment film. In a conventional IPS liquid crystal panel, an alignment film is formed on each of the insides of a pair of substrates that sandwich the liquid crystal composition (Patent Document 1).

However, in the conventional IPS type liquid crystal panel as described in Patent Document 1, a slight deviation may occur in the orientation direction of the alignment films formed on the pair of substrates sandwiching the liquid crystal layer. The deviation of the alignment film in the orientation direction is caused by, for example, a deviation during the rubbing treatment or a deviation during bonding of both substrates. If such a deviation in the orientation direction exists, a minute twist is generated in the liquid crystal molecules of the liquid crystal layer even when the voltage is turned off. The minute twist of the liquid crystal molecules when the power is turned off causes light leakage in the black display and causes a decrease in the contrast ratio. Further, in the conventional IPS type liquid crystal panel, a longitudinal electric field in a direction perpendicular to the substrate surface is formed on the comb tooth electrode for forming a transverse electric field in the direction horizontal to the substrate surface when the voltage is turned on. Therefore, the liquid crystal molecules are not sufficiently twisted in the lateral direction, and as a result, it becomes difficult for light to be transmitted on the comb tooth electrode, and the light transmittance of the liquid crystal panel is lowered. That is, the aperture ratio of the liquid crystal panel is reduced.

Therefore, Patent Document 2 proposes a liquid crystal panel in which a weak anchoring alignment film is formed on one of the opposed substrates and a strong anchoring alignment film is formed on the other substrate. In the liquid crystal panel described in Patent Document 2, the weak anchoring alignment film has a smaller binding force that constrains the orientation direction of the liquid crystal molecules when an electric field is applied than the strong anchoring alignment film. With such a configuration, the liquid crystal panel described in Patent Document 2 realizes a display having high light transmittance.

Japanese Patent No. 2940354 Japanese Unexamined Patent Publication No. 2016-170389

However, in the liquid crystal panel described in Patent Document 2, since the anchoring energy is small in the entire area of the weak anchoring alignment film formed on one of the substrates arranged to face each other, the restoring force at the time of voltage off is weak. It has become. Therefore, the responsiveness at the time of voltage off is lowered, and the response time (turn-off time) τ _off at the time of voltage off becomes long.

An object of the present invention is to provide a liquid crystal display device capable of improving the responsiveness at the time of voltage off while improving the light transmittance and the contrast ratio. Another object of the present invention is to provide a method for manufacturing a liquid crystal display device, which can easily manufacture such a liquid crystal display device without complicating the process.

According to one aspect of the present invention, the first substrate, the second substrate facing the first substrate, the liquid crystal layer sandwiched between the first substrate and the second substrate, and the above. A plurality of electrodes formed on the surface of the first substrate on the liquid crystal layer side and configured to be able to form an electric field in a plane horizontal to the first substrate, and a part of the plurality of electrodes. A first alignment film formed directly above, a second alignment film formed on the first substrate between the plurality of electrodes, and on the rest of the plurality of electrodes, and the first alignment film. It has a third alignment film formed on the liquid crystal layer side of the second substrate, and the anchoring energy of the first alignment film is smaller than the anchoring energy of the second and third alignment films. A liquid crystal display device characterized by this is provided.

According to another aspect of the present invention, the first substrate; the second substrate facing the first substrate; and the liquid crystal layer sandwiched between the first substrate and the second substrate; A plurality of electrodes formed on the surface of the first substrate on the liquid crystal layer side and configured to be able to form an electric field in a plane horizontal to the first substrate; a part of the plurality of electrodes. With a first alignment film formed directly above; a second alignment film formed on the first substrate between the plurality of electrodes and on the rest of the plurality of electrodes; It has a third alignment film formed on the liquid crystal layer side of the second substrate, and the anchoring energy of the first alignment film is higher than the anchoring energy of the second and third alignment films. A method for manufacturing a small liquid crystal display device, wherein a conductive film is formed on a surface of the first substrate on the liquid crystal layer side, and a photoresist film is formed on the conductive film. A step of exposing the first pattern and the second pattern to the photoresist film using a mask having the patterns of the plurality of electrodes including the first pattern and the second pattern having different transmission light transmission rates. By developing the photoresist film, a first photoresist film having the first pattern and a second photoresist film having the second pattern are formed on the conductive film. The step of forming the plurality of electrodes made of the conductive film by etching the conductive film using the first photoresist film and the second photoresist film as masks, and the first photoresist film. The step of forming the first alignment film made of the first photoresist film directly above a part of the plurality of electrodes by removing the second photoresist film while leaving the above. A liquid crystal display device comprising the step of forming the second alignment film on the first substrate between the plurality of electrodes and on the rest of the plurality of electrodes. A manufacturing method is provided.

According to the present invention, in a liquid crystal display device, it is possible to improve the responsiveness at the time of voltage off while improving the light transmittance and the contrast ratio. Further, according to the present invention, it is possible to easily manufacture a liquid crystal display device capable of improving the responsiveness at the time of voltage off while improving the light transmittance and the contrast ratio without complicating the process. ..

FIG. 1 is a cross-sectional view showing the structure of a liquid crystal display device when a liquid crystal having a positive dielectric anisotropy according to an embodiment of the present invention is used. FIG. 2 is a process cross-sectional view (No. 1) showing a method of manufacturing a liquid crystal display device when a liquid crystal having a positive dielectric anisotropy (positive type) according to an embodiment of the present invention is used. FIG. 3 is a process cross-sectional view (No. 2) showing a method of manufacturing a liquid crystal display device according to an embodiment of the present invention. FIG. 4 is a process cross-sectional view (No. 3) showing a method of manufacturing a liquid crystal display device according to an embodiment of the present invention. FIG. 5 is a process cross-sectional view (No. 4) showing a method of manufacturing a liquid crystal display device according to an embodiment of the present invention. FIG. 6 is a cross-sectional view showing the structure of a liquid crystal display device according to a modified example of the embodiment of the present invention. FIG. 7 is a cross-sectional view showing a cell configuration of a liquid crystal display device when a liquid crystal having a positive dielectric anisotropy (positive type) is used according to Examples and Comparative Examples. FIG. 8 is a graph showing the results of measuring a drive voltage-light transmittance curve showing the relationship between the drive voltage and the light transmittance of the liquid crystal panel for the liquid crystal display device according to the examples and comparative examples of the present invention.

[One Embodiment]
A liquid crystal display device and a method for manufacturing the liquid crystal display device according to an embodiment of the present invention will be described with reference to FIGS. 1 to 5.

First, the structure of the liquid crystal display device according to the present embodiment will be described with reference to FIG. FIG. 1 is a cross-sectional view showing the structure of a liquid crystal display device according to the present embodiment. Note that FIG. 1 illustrates a case where a liquid crystal layer is formed by using a positive liquid crystal material.

The liquid crystal display device according to the present embodiment has an IPS type liquid crystal panel, and controls the display by forming an electric field in a direction horizontal to the substrate surface. As shown in FIG. 1, the liquid crystal display device 10 according to the present embodiment includes an IPS type liquid crystal panel 12 and a backlight unit 14. The liquid crystal panel 12 includes a display area 16 including pixels and a pad area 18.

The liquid crystal panel 12 has a pair of substrates 20 and 22 arranged so as to face each other. The substrates 20 and 22 are arranged so as to face each other so as to sandwich the liquid crystal layer 24 in the display area 16. The substrates 20 and 22 are bonded to each other at predetermined intervals by a sealing material 26 arranged on the peripheral edge of the display area 16. The liquid crystal forming the liquid crystal layer 24 is sealed between the substrates 20 and 22 by the sealing material 26. The materials of the substrates 20 and 22 are not particularly limited as long as they are translucent substrates, but they are, for example, glass substrates. Further, as the liquid crystal material constituting the liquid crystal layer 24, for example, a nematic liquid crystal material having a positive dielectric anisotropy can be used, or a nematic liquid crystal material having a negative dielectric anisotropy can also be used. .. Note that FIG. 1 schematically shows liquid crystal molecules 242 in the liquid crystal layer 24 when the voltage with respect to the linear electrode 28 described later is off.

For example, the substrate 20 is a TFT substrate on which a thin film transistor (TFT) for switching pixels, a gate line, a source line, and the like are formed. The substrate 22 is a CF substrate on which a color filter (Color Filter, CF) is formed.

In the display area 16, among the substrates 20 and 22, a plurality of linear electrodes 28 are formed on the surface of the substrate 20 on the backlight unit 14 side on the liquid crystal layer 24 side. The plurality of linear electrodes 28 are arranged in parallel with a predetermined distance from each other to form a comb tooth electrode. More specifically, the plurality of linear electrodes 28 constitute a comb-shaped pixel electrode and a comb-shaped common electrode. FIG. 1 shows a cross section orthogonal to the longitudinal direction of the linear electrode 28. The plurality of linear electrodes 28 are configured to be capable of forming an electric field in a direction horizontal to the substrate surface of the substrate 20, that is, to form an electric field in a plane horizontal to the substrate 20.

The linear electrode 28 is, for example, a transparent electrode made of ITO (Indium Tin Oxide) having a high light transmittance T of 88%. The main material of the linear electrode 28 is not limited to ITO. The linear electrode 28 is preferably a transparent conductive film or a conductive film having a high light transmittance. As the main material of the linear electrode 28, for example, IZO (Indium Zinc Oxide, T = 85%) or AZO (Aluminum Doped Zinc Oxide, T = 92%) can be used instead of ITO. Further, GZO (Gallium Doped Zinc Oxide, T = 92%), ATO (Antimony Tin Oxide, T = 87%) and the like can also be used.

The control unit (not shown) of the liquid crystal display device 10 applies a voltage to the linear electrodes 28 of the substrate 20 to form an electric field in a direction horizontal to the substrate surface of the substrate 20 to rotate the liquid crystal molecules of the liquid crystal layer 24. By doing so, the display of the liquid crystal panel 12 is controlled.

On the other hand, in the pad region 18, a plurality of electrode pads 30 are formed on the substrate 20 in the same layer as the plurality of linear electrodes 28. The plurality of electrode pads 30 are made of the same material as the linear electrodes 28 in the display region 16. The plurality of electrode pads 30 are connected to a gate line, a source line, etc. (not shown) formed on the substrate 20 in the display area 16. A driver IC (Integrated Circuit) (not shown) is connected to the plurality of electrode pads 30 by mounting technology such as COF (Chip On Film), TAB (Tape Automated Bonding), and COG (Chip On Glass).

Polarizing plates 32 and 34 are provided on the outer surfaces of the liquid crystal panel 12 so as to sandwich the substrates 20 and 22. The orientation of the polarization axes of the polarizing plates 32 and 34 is set so that the light illuminated from the backlight unit 14 passes when a voltage is applied to the linear electrodes 28. For example, the directions of the polarization axes of the polarizing plates 32 and 34 are orthogonal to each other. The orientation of the polarization axes of the polarizing plates 32 and 34 may be set so that the light illuminated by the backlight unit 14 is blocked when a voltage is applied to the linear electrodes 28.

A strong anchoring film 36 is formed as an alignment film on the surface of the substrate 22 on the liquid crystal layer 24 side over the entire surface of the liquid crystal layer 24. The strong anchoring film 36 is made of, for example, a polyimide film that has been oriented by a rubbing method. The strong anchoring film 36 aligns the orientation of the liquid crystal molecules of the liquid crystal layer 24 with respect to the linear electrode 28 when the voltage is off, together with the strong anchoring film 40 on the substrate 20 side described later. The orientation direction of the liquid crystal molecules of the liquid crystal layer 24 when the voltage is off is, for example, a direction along the longitudinal direction of the linear electrode 28 or a direction forming a predetermined angle with respect to the longitudinal direction of the linear electrode 28.

On the other hand, between the substrate 20 and the liquid crystal layer 24, a weak anchoring film 38 is formed as an alignment film on a part of the plurality of linear electrodes 28 formed on the substrate 20. .. The weak anchoring film 38 is formed directly above a part of the plurality of linear electrodes 28. The weak anchoring film 38 is an alignment film having an anchoring energy smaller than that of the strong anchoring film 36 on the substrate 22 side and the strong anchoring film 40 described below. The anchoring referred to in the strong anchoring films 36 and 40 and the weak anchoring film 38 is related to anchoring in the azimuth direction, and the magnitude relationship of the anchoring energy is the magnitude relationship related to the anchoring energy in the azimuth direction. .. The weak anchoring film 38 is formed directly above, for example, every other linear electrode 28 among the plurality of linear electrodes 28 arranged in parallel with each other. The weak anchoring film 38 is made of a resin film, and more specifically, it is made of a photoresist film 52a used as a mask during etching for patterning the linear electrode 28 as described later.

The weak anchoring film 38 is not formed on any of the plurality of electrode pads 30 in the pad region 18 formed in the same layer as the linear electrode 28. The surface of each of the plurality of electrode pads 30 is exposed.

A strong anchoring film 40 is formed as an alignment film on the substrate 20 between the linear electrodes 28 on which the weak anchoring film 38 is formed. Further, a strong anchoring film 40 is also formed on the linear electrodes 28 other than the linear electrodes 28 on which the weak anchoring film 38 is formed, that is, on the rest of the plurality of linear electrodes 28. There is. The anchoring energy of the strong anchoring film 40 is, for example, about the same as the anchoring energy of the strong anchoring film 36. The strong anchoring film 40 is, for example, a polyimide film that has been subjected to an orientation treatment by a photoalignment method.

As described above, the strong anchoring film 36 is formed as the alignment film on the substrate 22 side. On the other hand, on the substrate 20 side, a weak anchoring film 38 is formed as an alignment film directly above a part of the plurality of linear electrodes 28. Further, on the substrate 20 side, the orientation is on the rest of the plurality of linear electrodes 28, that is, on the linear electrodes 28 other than the linear electrodes 28 on which the weak anchoring film 38 is formed and on the substrate 20. A strong anchoring film 40 is formed as a film.

The anchoring energy of the weak anchoring film 38 is smaller than the anchoring energy of the strong anchoring films 36 and 40, preferably ^10-6 J / m ² or less. The anchoring energy of the strong anchoring films 36 and 40 is larger than the anchoring energy of the weak anchoring films 38, preferably 10 ^-4 J / m ² or more.

A color filter 42 is provided between the substrate 22 and the strong anchoring film 36. The color filter 42 is composed of a pattern of the three primary colors of R (red) / G (green) / B (blue) of the color resist, a black matrix, a protective film, and the like, and R of the light emitted from the backlight unit 14. Passes light in the wavelength range of the three primary colors of / G / B.

The backlight unit 14 is a lighting device that emits light that illuminates the liquid crystal panel 12. The backlight unit 14 may be of an edge light type or a direct type. A light diffusion sheet or a prism sheet may be arranged between the backlight unit 14 and the liquid crystal panel 12.

The liquid crystal display device 10 according to the present embodiment is an IPS system that controls display by forming a horizontal electric field in a horizontal direction with the substrate surface of the substrate 20 and rotating liquid crystal molecules in the plane of the liquid crystal layer 24. However, in the above configuration, if a strong anchoring film is formed on the entire surface of the substrate 20 side including directly above the linear electrode 28 as in the conventional configuration described in the above-mentioned Patent Document 1, the linear electrode The liquid crystal molecule directly above 28 cannot be sufficiently rotated. This is because the component in the horizontal direction on the substrate surface of the electric field directly above the linear electrode 28 for forming the electric field is not large enough to overcome the binding of the strong anchoring film and rotate the liquid crystal molecules. be. Therefore, in this case, the light transmittance in the white display is lowered.

On the other hand, in the above configuration, when a weak anchoring film is formed on the entire surface of the substrate 20 side as in the conventional configuration described in Patent Document 2 described above, the orientation restricting force on the substrate 20 side is weakened. , High light transmittance can be realized and sufficient light transmittance in white display can be secured. However, in this case, since the restoring force of the liquid crystal molecules with respect to the linear electrode 28 at the time of voltage off decreases, the responsiveness at the time of voltage off decreases, and the response time τ _off at the time of voltage off becomes long.

In contrast to the conventional configuration, in the liquid crystal display device 10 according to the present embodiment, a weak anchoring film 38 having a relatively small anchoring energy is formed directly above a part of the plurality of linear electrodes 28. There is. On the linear electrode 28 on which the weak anchoring film 38 is formed, the orientation regulating force is weaker than in the region where the strong anchoring film 40 is formed. Therefore, in the liquid crystal display device 10 according to the present embodiment, even when the lateral component of the electric field is small, the liquid crystal molecules directly above the linear electrode 28 on which the weak anchoring film 38 is formed rotate. Sufficient light transmittance can be secured even immediately above the linear electrode 28. As a result, the liquid crystal display device 10 according to the present embodiment can improve the light transmittance.

Further, since the weak anchoring film 38 is formed, the orientation direction of the liquid crystal molecules on the substrate 20 side and the liquid crystal display on the substrate 22 side are directly above the linear electrode 28 on which the weak anchoring film 38 is formed. It is possible to suppress minute twists of liquid crystal molecules when the voltage is turned off due to the deviation of the orientation direction of the molecules. As a result, the black brightness can be reduced, and the contrast ratio can be improved in combination with the improvement of the light transmittance.

Moreover, the weak anchoring film 38 is formed by controlling the exposure amount of the photoresist film for each region by using a halftone mask in the exposure step of the photoresist film, as will be described later. Therefore, the liquid crystal display device 10 according to the present embodiment can be easily manufactured without increasing the number of steps and without complicating the steps.

Further, in the liquid crystal display device 10 according to the present embodiment, the linear electrode 28 on which the weak anchoring film 38 is formed directly above the substrate 20 between the linear electrodes 28 and the weak anchoring film 38 is formed directly above. A strong anchoring film 40 is formed on the linear electrodes 28 other than the above. As described above, the strong anchoring film 40 having a relatively large anchoring energy is formed in a region other than directly above a part of the plurality of linear electrodes 28, so that when the voltage on the linear electrodes 28 is off, The restoring force of the liquid crystal molecules is hardly reduced. Therefore, the liquid crystal display device 10 according to the present embodiment has a liquid crystal display when the voltage is off, as compared with a conventional configuration in which a weak anchoring film is formed on the entire surface of the substrate 20 side as described in Patent Document 2. The responsiveness can be improved, and the response time τ _off when the voltage is off can be shortened.

In this way, the liquid crystal display device 10 according to the present embodiment can improve the responsiveness at the time of voltage off while improving the light transmittance and the contrast ratio, and can achieve both the brightness and the responsiveness of the liquid crystal display. ..

Next, a method of manufacturing the liquid crystal display device according to the present embodiment will be described with reference to FIGS. 2 to 5. 2 to 5 are process cross-sectional views showing a method of manufacturing a liquid crystal display device according to the present embodiment.

First, as a comb-tooth electrode for forming an electric field (transverse electric field) in a direction horizontal to the substrate surface of the substrate 20, for example, ITO on the surface of the substrate 20 on the liquid crystal layer 24 side of the substrate 20 in the display region 16 and the pad region 18. A transparent conductive film 50 made of the above is formed (FIG. 2A). The substrate 20 is formed with a TFT, a gate line, a source line, and the like for switching pixels.

Next, a negative type photoresist material is applied onto the transparent conductive film 50 in the display region 16 and the pad region 18 by, for example, a spin coating method and prebaked to form a photoresist film 52 (FIG. 2B). .. The photoresist film 52 is made of a material that can function as a weak anchoring film 38.

Next, using the halftone mask 54 as a mask, the mask pattern of the halftone mask 54 is exposed on the photoresist film 52 (FIG. 3A). The halftone mask 54 has patterns 542a and 542b of a plurality of linear electrodes 28 and patterns 544 of a plurality of electrode pads 30 as mask patterns. Of the patterns 542a and 542b of the plurality of linear electrodes 28, the pattern 542a is a pattern of the linear electrodes 28 on which the weak anchoring film 38 is formed directly above. The pattern 542b is a pattern of the linear electrodes 28 other than the linear electrodes 28 on which the weak anchoring film 38 is formed. The transmittances of the exposure light of the patterns 542a, 542b, and 544 are different from each other. That is, the transmittance of the exposure light of the pattern 542a is higher than the transmittance of the exposure light of the pattern 542b and the transmittance of the exposure light of the pattern 544. Further, the transmittance of the exposure light of the pattern 542b is equal to the transmittance of the exposure light of the pattern 544. As the exposure light, ultraviolet light or the like can be selected depending on the type of the photoresist film 52.

The exposure amounts of the photoresist films 52a, 52b, 52c to which the patterns 542a, 542b, and 544 of the photoresist film 52 are exposed differ depending on the exposure using the halftone mask 54 having different transmittances of the exposure light. .. That is, the exposure amount of the photoresist film 52a to which the pattern 542a is exposed is larger than the exposure amount of the photoresist film 52b to which the pattern 542b is exposed and the exposure amount of the photoresist film 52c to which the pattern 544 is exposed. In this way, the degree of curing of the photoresist films 52a, 52b, 52c is adjusted by controlling the exposure amount of the photoresist films 52a, 52b, 52c by exposure using the halftone mask 54.

Next, the photoresist film 52 is developed to remove the unexposed photoresist film 52, and then post-baking is performed. As a result, the photoresist films 52a, 52b, and 52c are formed on the transparent conductive film 50 (FIG. 3 (b)). As described above, since the exposure amount of the photoresist film 52a is larger than the exposure amount of the photoresist films 52b and 52c, the curing degree of the photoresist film 52a is higher than the curing degree of the photoresist films 52b and 52c. There is. Therefore, after development, the film thickness of the photoresist film 52a is thicker than the film thickness of the photoresist films 52b and 52c.

Next, using the photoresist films 52a, 52b, and 52c as masks, the transparent conductive film 50 is etched and patterned by, for example, wet etching. As a result, a plurality of linear electrodes 28 made of the transparent conductive film 50 are formed in the display region 16, and a plurality of electrode pads 30 made of the transparent conductive film 50 are formed in the pad region 18 (FIG. 4A). ).

Then, for example, by immersing the photoresist film 52a in a stripping solution, the photoresist film 52a remains directly above the linear electrode 28, and the photoresist film 52b on the linear electrode 28 and the photoresist film 52c on the electrode pad 30 are left. To remove. Since the photoresist film 52a is thicker than the photoresist films 52b and 52c, it can be selectively left directly above the linear electrode 28. In this way, a weak anchoring film 38 made of a photoresist film 52a is formed directly above a part of the plurality of linear electrodes 28 (FIG. 4B). If the photoresist films 52b and 53c cannot be completely removed by the peeling step, they are removed by plasma ashing or the like.

The thickness of the photoresist films 52a, 52b, 52c so that the photoresist films 52b, 52c among the photoresist films 52a, 52b, 52c disappear selectively in the etching process shown in FIG. 4A. Can be set. In this case, the peeling process and the ashing process shown in FIG. 4B can be omitted.

Next, a polyimide film is formed on the substrate 20 in the display region 16 by, for example, a printing method. Here, the photoresist film 52a constituting the weak anchoring film 38 does not have an affinity for the polyimide film. Therefore, the polyimide film is not formed on the weak anchoring film 38 made of the photoresist film 52a, and is linear on the substrate 20 between the linear electrodes 28 and on the weak anchoring film 38 not directly above. It is formed on the electrode 28. Subsequently, the polyimide film is subjected to an orientation treatment by, for example, a photo-alignment method. In this way, the strong anchoring film 40 made of the polyimide film is formed on the substrate 20 between the linear electrodes 28 and on the linear electrodes 28 on which the weak anchoring film 38 is not formed directly above (FIG. 5 (a). )).

On the other hand, a color filter 42 is formed on the substrate 22 in the display area 16. Subsequently, a polyimide film is formed on the color filter 42. Subsequently, the polyimide film is subjected to an orientation treatment by, for example, a rubbing method, a photo-alignment method, or the like. In this way, a strong anchoring film 36 made of a polyimide film is formed on the color filter 42.

Next, the liquid crystal layer 24 is sealed between the substrates 20 and 22 by the ODF (One Drop Fill) method. First, a sealing material 26 made of an ultraviolet curable resin is applied onto one of the substrates 20 and 22 at the peripheral edge of the display area 16. Subsequently, the liquid crystal material is dropped onto one of the substrates 20 and 22 coated with the sealing material 26. Subsequently, one of the substrates 20 and 22 on which the liquid crystal material is dropped and the other of the substrates 20 and 22 are bonded to each other by the sealing material 26. A liquid crystal layer 24 made of a dropped liquid crystal material is formed between the substrates 20 and 22. Subsequently, the sealing material 26 is cured by irradiating with ultraviolet light. In this way, the substrate 20 and the substrate 22 are bonded together so as to sandwich the liquid crystal layer 24 made of the liquid crystal material by the ODF method, and the liquid crystal layer 24 is sealed between the substrates 20 and 22 (FIG. 5B).

After that, the polarizing plates 32 and 34 are attached to the substrates 20 and 22 by a normal process, the driver IC is mounted, the backlight unit 14 is arranged, and the like. In this way, the liquid crystal display device 10 according to the present embodiment shown in FIG. 1 is manufactured.

As described above, in the present embodiment, the exposure using the halftone mask 54 as a mask exposes the photoresist films 52a, 52b, 52c used as a mask when etching the transparent conductive film 50 constituting the linear electrode 28. Control the amount. As a result, the weak anchoring film 38 made of the photoresist film 52a is formed directly above a part of the plurality of linear electrodes 28. Therefore, in the present embodiment, an additional step such as a separate step of patterning the photoresist film is not required to form the weak anchoring film 38, and the number of steps does not increase. Therefore, according to the present embodiment, the liquid crystal display device 10 shown in FIG. 1 can be easily manufactured without complicating the process.

As described above, according to the present embodiment, in the liquid crystal display device 10, it is possible to improve the responsiveness at the time of voltage off while improving the light transmittance and the contrast ratio. Further, according to the present embodiment, the liquid crystal display device 10 capable of improving the responsiveness at the time of voltage off while improving the light transmittance and the contrast ratio can be easily manufactured without complicating the process. Can be done.

(Modification example)
Next, a liquid crystal display device according to a modified example of the present embodiment will be described with reference to FIG. FIG. 6 is a cross-sectional view showing the structure of the liquid crystal display device according to the modified example of the present embodiment.

In the liquid crystal display device 10 shown in FIG. 1, the weak anchoring film 38 was formed directly above every other linear electrode 28 among the plurality of linear electrodes 28 arranged in parallel with each other. It is not limited to this. The weak anchoring film 38 may be formed directly above the plurality of linear electrodes 28 among the plurality of linear electrodes 28 arranged in parallel with each other.

For example, the weak anchoring film 38 can be formed directly above every two linear electrodes 28 among the plurality of linear electrodes 28. In the liquid crystal display device 100 according to the modification shown in FIG. 6, the weak anchoring film 38 is formed directly above every two linear electrodes 28 among the plurality of linear electrodes 28 arranged in parallel with each other. ..

In this way, the ratio of the linear electrodes 28 in which the weak anchoring film 38 is formed directly above the plurality of linear electrodes 28 can be changed. Thereby, the brightness and responsiveness of the liquid crystal display can be adjusted.

Further, in the above, by controlling the exposure amount of the photoresist films 52a, 52b, 52c by exposure using the halftone mask 54, the weak anchoring film 38 is directly above a part of the plurality of linear electrodes 28. Was selectively formed, but is not limited to this. For example, the weak anchoring film 38 may be selectively formed directly above a part of the plurality of linear electrodes 28 by separately coating the materials of the weak anchoring film 38 by a printing method such as an inkjet method. can.

(Evaluation results)
Next, the evaluation result of the liquid crystal display device according to the present embodiment will be described.

First, for each of the liquid crystal display device according to Examples 1 and 2 and Comparative Examples 1, 2 and 3, and evaluating the response speed by measuring the response time t _off when the voltage is turned off. The cell configuration of the liquid crystal display device according to each Example and Comparative Example is as follows. Note that FIG. 7A is a cross-sectional view showing the cell configuration of the first embodiment. FIG. 7B is a cross-sectional view showing the cell configuration of Comparative Example 1.

The cell configuration of the first embodiment is as follows. Glass substrates were used as the substrates 20 and 22, respectively. ITO was used as the material of the linear electrode 28 constituting the comb tooth electrode. Further, a strong anchoring film 40 was formed on the substrate 20 on which the linear electrode 28 was formed. Polyimide was used as the material of the strong anchoring film 40, and the orientation treatment was performed by the rubbing method. A weak anchoring film 38 was formed on the strong anchoring film 40 by an inkjet method. The weak anchoring film 38 was formed directly above every other linear electrode 28 among the plurality of linear electrodes 28. The gap between the substrates 20 and 22, that is, the thickness of the liquid crystal layer 24 was set to 3.0 μm. As the material of the strong anchoring film 36 on the substrate 22 side, the same polyimide as the strong anchoring film 40 was used, and the orientation treatment was performed by the rubbing method. An ITO film 60 was formed on the outer surface of the substrate 20.

The cell configuration of Example 2 is the same as the cell configuration of Example 1 except that the weak anchoring film 38 is formed directly above every two linear electrodes 28 among the plurality of linear electrodes 28. be.

The cell configuration of Comparative Example 1 is the same as that of Example 1 except that the weak anchoring film 38 is formed on the entire surface without forming the strong anchoring film 40.

The cell configuration of Comparative Example 2 is the same as the cell configuration of Example 1 except that the weak anchoring film 38 is formed directly above each of the plurality of linear electrodes 28.

The cell configuration of Comparative Example 3 is the same as that of Example 1 except that the weak anchoring film 38 is not formed, that is, the strong anchoring film 40 is formed on the entire surface.

Cell configuration of Examples 1 and 2 and Comparative Examples 1, 2, 3, and each show the result of measuring the response time _{t off} when the voltage off Table 1.

_{As shown in Table 1, the response time to off at the time of voltage off} is shortened in Examples 1 and 2 as compared with Comparative Example 1 in which the weak anchoring film 38 is formed on the entire surface, and the response time at the time of voltage off is shortened. It can be seen that the responsiveness of is improved.

Further, for each of the liquid crystal display devices according to Examples 1 and 2 and Comparative Examples 1, 2 and 3, a drive voltage-light transmittance curve (VT curve) showing the relationship between the drive voltage and the light transmittance of the liquid crystal panel. Was measured. FIG. 8 is a graph showing the results of measuring the VT curve.

As is clear from FIG. 8, in both Examples 1 and 2, the light transmittance is higher than that of Comparative Example 3 in which the strong anchoring film 40 is formed on the entire surface, and the weak anchoring film 38 is formed on the entire surface. A light transmittance similar to that of Comparative Example 1 was obtained.

From the above evaluation results, it can be seen that in Examples 1 and 2, the light transmittance could be improved and the responsiveness at the time of voltage off could be improved.

[Modification Embodiment]
The present invention is not limited to the above embodiment, and various modifications are possible.

For example, in the above embodiment, the case where a plurality of linear electrodes 28 are formed has been described as an example, but the present invention is not limited to this. Instead of the plurality of linear electrodes 28, electrodes having various shapes can be formed.

Further, in the above embodiment, the case where the alignment film made of the polyimide film is formed as the strong anchoring films 36 and 40 has been described as an example, but the present invention is not limited to this. As the strong anchoring films 36 and 40, alignment films made of various materials can be formed.

10 ... Liquid crystal display device 12 ... Liquid crystal panel 16 ... Display area 18 ... Pad area 20 ... Substrate 22 ... Substrate 24 ... Liquid crystal layer 28 ... Linear electrode 30 ... Electrode pad 36 ... Strong anchoring film 38 ... Weak anchoring film 40 ... Strong anchoring film

Claims (14)

The first board and
A second substrate facing the first substrate and
A liquid crystal layer sandwiched between the first substrate and the second substrate,
It formed on the surface of the liquid crystal layer side of the first substrate, and a plurality of electrodes formed configured to be capable of field before Symbol first substrate and a horizontal plane,
A first alignment layer formed directly on the part of the electrode of the plurality of electrodes,
A second alignment film formed on the first substrate between the plurality of electrodes and on an electrode other than the part of the plurality of electrodes.
It has a third alignment film formed on the liquid crystal layer side of the second substrate, and has a third alignment film.
A liquid crystal display device characterized in that the anchoring energy of the first alignment film is smaller than the anchoring energy of the second and third alignment films. The liquid crystal display device according to claim 1, wherein each of the plurality of electrodes is a linear electrode and constitutes a comb tooth electrode. The liquid crystal display device according to claim 2, wherein the first alignment film is formed immediately above the linear electrodes every other or a plurality of electrodes. It has an electrode pad formed on the first substrate and has an electrode pad.
The liquid crystal display device according to any one of claims 1 to 3, wherein the first alignment film is not formed on the electrode pad. The liquid crystal display device according to claim 4, wherein the electrode pad is formed in the same layer as the plurality of electrodes. The liquid crystal display device according to claim 4 or 5, wherein the electrode pad is made of the same material as the plurality of electrodes. The liquid crystal display device according to any one of claims 1 to 6, wherein the first alignment film is made of a photoresist film. The liquid crystal display device according to any one of claims 1 to 7, wherein the anchoring energy of the first alignment film is ^10-6 J / m ^{2 or less.} The liquid crystal display device according to any one of claims 1 to 8, wherein the anchoring energy of the second alignment film is equal to the anchoring energy of the third alignment film. The liquid crystal display device according to any one of claims 1 to 9, wherein the main material of the plurality of electrodes is any one of ITO, IZO, AZO, GZO and ATO. A first substrate; a second substrate facing the first substrate; a liquid crystal layer sandwiched between the first substrate and the second substrate; the liquid crystal layer side of the first substrate. is formed on the surface, the first substrate and the horizontal in a plurality of formed configured to be capable of field on the surface electrode; first formed directly on a part of electrodes of the plurality of electrodes Alignment film; and a second alignment film formed on the first substrate between the plurality of electrodes and on electrodes other than the partial electrodes of the plurality of electrodes; It has a third alignment film formed on the liquid crystal layer side of the second substrate, and the anchoring energy of the first alignment film is smaller than the anchoring energy of the second and third alignment films. It is a manufacturing method of a liquid crystal display device.
A step of forming a conductive film on a surface of the first substrate on the liquid crystal layer side,
The step of forming a photoresist film on the conductive film and
The photoresist film is exposed to the first pattern and the second pattern by using a mask having the patterns of the plurality of electrodes including the first pattern and the second pattern having different transmittances of exposure light from each other. Process and
A step of forming a first photoresist film having the first pattern and a second photoresist film having the second pattern on the conductive film by developing the photoresist film.
A step of forming the plurality of electrodes made of the conductive film by etching the conductive film using the first photoresist film and the second photoresist film as masks.
While leaving the first photoresist film, by removing the second photoresist film, the part of the electrode directly above one of said plurality of electrodes, the first consisting of the first photoresist film The step of forming the alignment film of 1 and
It is characterized by having a step of forming the second alignment film on the first substrate between the plurality of electrodes and on electrodes other than the partial electrodes among the plurality of electrodes. A method of manufacturing a liquid crystal display device. In the step of exposing the photoresist film, the third pattern is further exposed by using the mask further having a third pattern having a different transmittance of the exposure light from the first pattern.
In the step of developing the photoresist film, a third photoresist film having the third pattern is further formed on the conductive film.
In the step of forming the plurality of electrodes, the conductive film is etched using the third photoresist film as a mask to further form an electrode pad made of the conductive film.
The method for manufacturing a liquid crystal display device according to claim 11, wherein in the step of forming the first alignment film, the third photoresist film is further removed. The method for manufacturing a liquid crystal display device according to claim 11 or 12, wherein in the step of forming the first alignment film, the second photoresist film is removed by ashing. In the step of forming the second alignment film, a polyimide film is formed on the first substrate between the plurality of electrodes and on an electrode other than the part of the plurality of electrodes. The liquid crystal display device according to any one of claims 11 to 13, wherein the polyimide film is subjected to an alignment treatment by a photoalignment method to form a second alignment film made of the polyimide film. Manufacturing method.

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