JP2000206534A - Production of liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a liquid crystal display device having wide viewing angle characteristics in a comparatively simple process with high yield by providing a process for laminating a pair of substrates with the faces having electrodes formed facing each other and a process for supplying a liquid crystal material having positive or negative dielectric anisotropy to the space between the pair of substrates. SOLUTION: A pair of substrates 32, 34 having electrodes 31, 33 are prepared, and a first coating liquid containing a hardening resin material is selectively applied by an ink-jet method on the surface of at least one substrate 32 where the electrode 31 is formed. The selectively applied first coating liquid is dried and hardened to form projections 36. The pair of substrates 32, 34 are laminated with the faces having electrodes 31, 33 formed facing each other, and a liquid crystal material having positive or negative dielectric anisotropy is supplied to the space between the pair of substrates 32, 34. By this constitution, since an expensive device or a photomask is not required, the liquid crystal display device having wide viewing angle characteristics can be produced in a rather easy process with high yield.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display device and a method for manufacturing the same. For example, a liquid crystal display device having a wide viewing angle characteristic used for a portable information terminal, a personal computer, a word processor, an amusement device, an educational device, a television device, a display plate using a shutter effect, a window, a door, a wall, and the like, and manufacturing thereof About the method.

[0002]

2. Description of the Related Art As a liquid crystal display device having a wide viewing angle characteristic, the present inventors have proposed a display mode (axially symmetry) in which liquid crystal molecules are axially symmetrically arranged for each picture element.
icAligned Microcell Mode:
An ASM mode liquid crystal display device is disclosed in, for example,
No. 0728. This publication discloses a technique for forming a liquid crystal region in which liquid crystal molecules are axially symmetrically aligned by utilizing phase separation from a mixture of a liquid crystal material and a photocurable resin. The liquid crystal display device disclosed in this publication,
This is a P-type display mode liquid crystal display device in which a nematic liquid crystal material having a positive dielectric anisotropy (Np-type liquid crystal material) is used, and liquid crystal molecules are aligned perpendicular to a substrate surface when a saturation voltage is applied.

FIG. 1 schematically shows a liquid crystal display device 20 disclosed in Japanese Patent Application Laid-Open No. Hei 7-120728, which has a wide viewing angle characteristic and can obtain good display quality. A liquid crystal layer 27 is sandwiched between a substrate 21 on which a picture element electrode 22 is formed and a substrate 23 on which a counter electrode 24 is formed. The liquid crystal layer 27 has a polymer region (polymer wall) 28 formed by phase separation and a liquid crystal region 29 substantially surrounded by the polymer region 28. The liquid crystal regions 29 are typically formed regularly corresponding to picture elements. The liquid crystal molecules (not shown) in the liquid crystal region 29 are formed in the respective liquid crystal regions 29 by the wall effect of the polymer region 28.
Are oriented axially symmetrically. As a result of the axially symmetric alignment, the liquid crystal display device 20 has a wide viewing angle characteristic.

[0004] Further, since it has a microcell structure which is completely sealed between the substrates by the polymer region 28, it does not affect the display when pressed from the outside, and furthermore, it has a very large liquid crystal display. In this case, the problem that the liquid crystal panel swells due to the weight of the liquid crystal material when the liquid crystal panel is erected and the display characteristics are deteriorated does not occur.

[0005]

However, in order to manufacture the ASM mode liquid crystal display device disclosed in the above-mentioned Japanese Patent Application Laid-Open No. Hei 7-120728, a phase separation process requiring relatively complicated temperature control is required. , There is a problem that the yield is low. In addition, it is difficult to control the position of the central axis of the liquid crystal molecules in the axially symmetrical alignment, and the position of the central axis is not constant for each picture element or deviates from almost the center of the picture element. When the liquid crystal display device was observed by using the liquid crystal display device, a rough display was obtained, and a sufficient display quality could not be obtained.

A conventional ASM mode liquid crystal display device using a liquid crystal material having a positive dielectric anisotropy requires a large light-shielding portion of a black matrix (BM) in order to obtain a display with high contrast. It was necessary to set and sufficiently prevent light leakage during black display.

As a method for solving the above-mentioned problems of the position control of the central axis of the axisymmetric orientation and the display quality, the present inventors have proposed the following.
In JP-A-10-186330, the liquid crystal molecules of a liquid crystal layer have negative dielectric anisotropy, and when no voltage is applied, the liquid crystal molecules are oriented perpendicular to a pair of substrates. A liquid crystal display device in which liquid crystal molecules are aligned in an axially symmetric manner for each of a plurality of picture element regions is proposed.

The liquid crystal display device disclosed in the above publication operates in a normally black mode using a nematic liquid crystal material (Nn type liquid crystal material) having a negative dielectric anisotropy. High contrast can be obtained as compared with an ASM mode liquid crystal display device using a liquid crystal material having anisotropy. In addition, since the convex portion is formed by using photolithography technology instead of the polymer region for aligning the liquid crystal molecules in an axially symmetric manner, a complicated temperature control process is not required because the convex portion is formed without using the phase separation method. Becomes

FIGS. 2A and 2B schematically show the structure of the projection of the liquid crystal display device disclosed in Japanese Patent Application Laid-Open No. 10-186330. A first convex portion 66 (for example, OMR83 or photosensitive polyimide manufactured by Tokyo Ohka Co., Ltd.) for defining a liquid crystal region and a second convex portion 65 for defining a cell gap are formed on a substrate 62 having a transparent electrode 63 formed on a surface thereof. (For example, OMR83 or photosensitive polyimide). Further, a vertical alignment film 68 (for example, JALS-204 manufactured by Nippon Synthetic Rubber Co., Ltd.) is formed to cover them. The manufacturing process for forming the first convex portion 66 and the second convex portion 65 requires two application steps and two photolithography steps with high patterning accuracy, which requires a long manufacturing process and The efficiency of using the material for forming the layer is low, causing a decrease in yield (non-defective product rate) and an increase in cost.

Therefore, the inventor of the present application examined a method of forming the convex portion in the above-described ASM mode liquid crystal display device by using an ink jet method. A manufacturing method of a liquid crystal display device using an ink jet method is disclosed in the following publications.

Japanese Patent Application Laid-Open Nos. 9-5730 and 8
Japanese Patent Application Laid-Open No. 286028 discloses a method of forming a color filter substrate using an ink jet method.
Japanese Patent Application Laid-Open No. 9-5730 discloses a technique of forming a resin black matrix having a thin film thickness that does not impair flatness and having a high optical density by using an inkjet method. JP-A-8-286028 discloses that
Forming an ink layer using an inkjet method,
The manufacturing cost can be reduced by a process including a step of irradiating a laser beam to remove a part of the ink layer to form a light-shielding member and a step of forming a colored member on a substrate on which the light-shielding member is not formed. Has been disclosed.

Japanese Patent Application Laid-Open No. 9-105946 discloses that
A method for manufacturing a liquid crystal display device in which a mixed liquid of a granular spacer and a curable resin is applied using an inkjet method to form a spacer at a predetermined position is disclosed.

However, as a result of the study by the present inventor, the ink jet method disclosed in
It has been found that there are the following problems in using the convex portion of the SM mode liquid crystal display device for forming the convex portion.

In the technique disclosed in Japanese Patent Application Laid-Open No. 9-5730, the thickness of the light-shielding portion is too small because the formed film is excellent in flatness. In order to make the film thickness of, for example, 3 μm, printing must be performed a plurality of times, which is not practical, and the cross-sectional shape of the light-shielding portion does not provide a sufficient pretilt for stabilizing the ASM orientation. .

In Japanese Patent Application Laid-Open No. Hei 8-286860, manufacturing cost is reduced by using a laser beam, for example, an excimer laser beam irradiating step. However, maintenance of the laser is costly and output intensity is unstable. And the process margin is narrow. Since the area that can be irradiated with laser light at one time is very narrow, there is a limit to a method for manufacturing a large-sized liquid crystal display device such as a 42-inch type.

Furthermore, in Japanese Patent Application Laid-Open No. 9-105946, a cell thickness holding material such as plastic beads cannot serve as a control factor for stabilizing ASM orientation.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method capable of relatively easily manufacturing a liquid crystal display device having a wide viewing angle characteristic at a high yield. It is in.

[0018]

A method of manufacturing a liquid crystal display device according to the present invention comprises a pair of substrates each having an electrode, a liquid crystal layer sandwiched between the pair of substrates, and at least one of the pair of substrates. The substrate has a projection on the surface on the liquid crystal layer side,
The liquid crystal layer has a plurality of liquid crystal regions defined by the projections, the liquid crystal layer has a plurality of liquid crystal regions defined by the projections, and the liquid crystal molecules of the liquid crystal layer have a positive or negative dielectric constant. Having anisotropy, the liquid crystal molecules are aligned substantially perpendicular to the surfaces of the pair of substrates during black display, and the liquid crystal molecules are axially symmetrically aligned for each of the plurality of liquid crystal regions during white display. A method for manufacturing a liquid crystal display device, comprising: providing a pair of substrates each having an electrode; and forming a first substrate including a curable resin material on a surface of the at least one substrate on which the electrodes are formed.
A step of selectively applying a coating liquid by an inkjet method,
Drying and curing the selectively applied first coating liquid to form a convex portion; and bonding the pair of substrates so that the surfaces on which the electrodes are formed face each other. Supplying a liquid crystal material having positive or negative dielectric anisotropy between the pair of substrates, thereby achieving the above object.

In the first coating liquid application step, the discharge amount of the first coating liquid may be controlled based on a coating time.

[0020] In the bonding step, it is preferable that the pair of substrates be bonded to each other with the convex portions serving as spacers.

In the first application liquid applying step, it is preferable that the first application liquid is simultaneously applied to different positions from a plurality of nozzles.

In the first application liquid applying step, it is preferable that the first application liquid is applied on the surface of the at least one substrate in a regular pattern corresponding to picture elements.

In the first application liquid application step, the first application liquid may be applied linearly, dashedly, or dottedly on the surface of the at least one substrate.

In the first application liquid application step, it is preferable that the first application liquid is applied in a grid pattern on a surface of the at least one substrate at a position corresponding to a periphery of a picture element.

The step of supplying the liquid crystal material is a step of supplying a precursor mixture containing the liquid crystal material and the photocurable resin, and the step of heating the precursor mixture to make it compatible. To the precursor mixture in the compatibilized state, the photocurable resin is cured by irradiating light while applying a voltage equal to or higher than a predetermined voltage, and the plurality of liquid crystal regions defined by the protrusions are formed. Forming a central axis of the axially symmetric alignment of the liquid crystal molecules at substantially the center of each, and forming an alignment fixed layer in which the axially symmetric alignment is stored in the liquid crystal molecules.

The liquid crystal material is supplied by a roll coater method or an ink jet method into a region defined by the projections formed on the surface of the at least one substrate, and then the pair of substrates is bonded. It may be.

A second alignment material containing a horizontal alignment material or a vertical alignment material is formed on the surface of the pair of substrates on which the electrodes are formed.
The method may further include a step of selectively supplying a coating liquid and a step of drying the second coating liquid to form a horizontal alignment layer or a vertical alignment layer.

The operation of the present invention will be described below.

The liquid crystal display device of the present invention has a wide viewing angle characteristic because the liquid crystal molecules are aligned axially symmetrically in each of a plurality of liquid crystal regions during white display. Since a convex portion for axially symmetrically aligning liquid crystal molecules in each liquid crystal region is formed using an inkjet method, a material can be selectively supplied to a predetermined position with high positional accuracy when a convex portion is to be formed. it can. Therefore, the photolithography step required for the conventional manufacturing method is not required, so that the manufacturing process can be simplified and the material use efficiency can be improved. As a result, a liquid crystal display device having a wide viewing angle characteristic can be supplied at a lower price than before.

Further, the curable resin material for forming the convex portions does not need to be a photosensitive resin that can be patterned by photolithography as in the conventional case, and a relatively inexpensive curable resin can be used. . Further, by using a thermosetting resin as the curable resin material, the material cost can be further reduced and the curing step can be simplified.

By controlling the amount of material to be applied from the ink jet head with time, an accurate application liquid supply operation can be reliably performed.

By using a projection for controlling the alignment of liquid crystal molecules as a spacer for defining the thickness of the liquid crystal layer,
It is not necessary to separately provide a spacer. In addition, by forming the convex portion using a thermosetting resin, a spacer having higher strength than when using a photocurable resin can be obtained.

By simultaneously applying the material for forming convex portions to different positions, a large-sized liquid crystal display device (for example, 40
Inches or more) in a shorter cycle time.

By arranging the projections regularly so as to correspond to the picture elements of the display device, a liquid crystal region having an axially symmetric orientation can be formed corresponding to the picture elements. A display device can be manufactured. Further, by arranging the projections so as to exist outside the picture element, it is possible to prevent a decrease in aperture ratio. When the picture element is, for example, a rectangle, it may be provided so as to form a plurality of liquid crystal regions in each picture element. The projections are regularly formed in association with the components formed corresponding to the picture elements of the TFT substrate, the plasma generation substrate and the color filter substrate.

If the projections are formed in a linear, dashed or dotted pattern, a region sealed by the projections is not formed.
The liquid crystal material can be injected by a conventional vacuum injection method.
The arrangement and density of the convex portions are optimized in consideration of the correspondence with the picture elements, the stability of the axially symmetric orientation, and the strength (when the spacer is also used).

By arranging the convex portions in a lattice at positions corresponding to the periphery of the picture element, it is possible to prevent a decrease in aperture ratio and to stably form and maintain an axially symmetric orientation. Further, by providing the material forming the convex portions with a light shielding property, the lattice-shaped convex portions can be used as a black matrix.

By applying a predetermined voltage to the liquid crystal material, the central axis of the axis symmetric alignment of the liquid crystal molecules can be formed at the center of each liquid crystal region. As a result, it is possible to further improve the uniformity of the viewing angle characteristics.

By injecting a liquid crystal material into a region defined by the protrusion on the surface of the substrate on which the protrusion is formed (a region to be a liquid crystal region of a liquid crystal display device) by using a roll coater method or an ink jet method, the liquid crystal is injected. The utilization efficiency of the material can be improved, and the injection time can be shortened. Reducing the injection time is particularly effective in a method for manufacturing a large liquid crystal display device. Furthermore, by performing the step of forming the vertical alignment layer using a roll coater method, the use efficiency of the material can be greatly improved as compared with the conventional spin coating method.

[0039]

Embodiments of the present invention will be described below. (Basic Operation) The operation principle of the liquid crystal display device 100 of the present invention will be described with reference to FIG. When an Nn-type liquid crystal material is used, FIGS. 3A and 3B show a state when no voltage is applied, and FIGS. 3C and 3D show a state when a predetermined voltage is applied. Here, the predetermined voltage refers to a voltage equal to or higher than a voltage at which Nn-type liquid crystal molecules start to tilt in the direction of an electric field. Also,
3A and 3C are cross-sectional views, and FIGS. 3B and 3D.
Shows the result of observing the upper surface with a polarizing microscope in a crossed Nicols state.

In the liquid crystal display device 100, a liquid crystal layer 40 composed of liquid crystal molecules 42 having a negative dielectric anisotropy is sandwiched between a pair of substrates 32 and 34. Transparent electrodes 31 and 33 are formed on the surfaces of the pair of substrates 32 and 34 that are in contact with the liquid crystal layer 40, respectively.
a and 38b are formed. In addition, at least in the central part of the picture element area of at least one of the electrodes,
5 are formed. The surface of at least one of the pair of substrates 32 and 34 that is in contact with the liquid crystal layer 40 has a convex portion 3.
6 are formed.

The "picture element" is generally defined as a minimum unit for displaying. The term "picture element area" used in the specification of the present application refers to a partial area of the display element corresponding to "picture element". Further, the axially symmetric orientation refers to an orientation such as a radial orientation having an axial center, a concentric (tangential) orientation, a twisted orientation, and the like.

As will be described later, the liquid crystal region 40a is defined by the convex portion 36. In addition, by applying a predetermined voltage, the liquid crystal molecules 42 in the liquid crystal region 40a are aligned in an axially symmetric manner. Further, the position of the central axis of the axially symmetric orientation is controlled by the region 35 having no electrode. Therefore, FIG.
As shown in (c), the liquid crystal molecules 42 are axially symmetrically aligned in the liquid crystal region 40a defined by the convex portions 36 around the axis symmetric alignment central axis 44 formed in the region 35 without electrodes. As schematically shown in FIGS. 4A and 4B, the liquid crystal molecules 42 in the region where the electrode-free region (opening) 35 is formed maintain a vertically aligned state even when a voltage is applied. The orientation of the liquid crystal molecules 42 in the region around the electrodeless region 35 is stable due to interaction with itself, and the liquid crystal molecules 42 in each liquid crystal region 40a are provided at the pixel central portion. It is axially symmetrically oriented toward the region 35 where there is no electrode.

When an Nn-type liquid crystal material is used, when no voltage is applied, as shown in FIG. 3 (a), the liquid crystal molecules 42 are controlled by the alignment regulating force of the vertical alignment layers 38a and 38b to adjust the substrate surface (more strictly). Are oriented in a direction perpendicular to the surface of the vertical alignment layer). Observation of the picture element region in a state where no voltage is applied by a crossed Nicol state polarizing microscope shows a dark field (normally black mode) as shown in FIG. 3B.

On the other hand, when a voltage higher than the threshold voltage is applied,
The liquid crystal molecules having negative dielectric anisotropy have 42
Since a force acts to orient the long axis of the two in a direction perpendicular to the direction of the electric field, the substrate is inclined from a direction perpendicular to the substrate as shown in FIG. 3C (halftone display state). When the picture element region in this state is observed with a polarization microscope in a crossed Nicols state, as shown in FIG. 3D, an extinction pattern is observed in a direction along 45 ° with respect to the polarization axis.

(Protrusion Defining Liquid Crystal Region) The liquid crystal display device 100 shown in FIG. 3 has a projection 36 surrounding a picture element region. When there is no convex portion 36 and the thickness (cell gap) of the liquid crystal layer 40 is uniform, the position or size where a liquid crystal domain (continuously aligned region: a region where no disclination line is generated) is formed. Is not specified, a random orientation state occurs, and the display becomes rough in the halftone display.

In the example shown in FIG. 3, one picture element region has one pixel.
Although the example in which one liquid crystal region 40a is formed is shown, the correspondence between the picture element region and the liquid crystal region 40a is not limited to this. However, in order to improve the display quality, the liquid crystal region 40a
Is preferably formed corresponding to the picture element region. In the case of a picture element having a large aspect ratio (long picture element), a plurality of picture element regions may be formed for one long picture element. The number of liquid crystal regions formed corresponding to the picture elements is preferably as small as possible as long as the axially symmetric alignment can be stably formed.

The convex portion 36 defines the position and size of the liquid crystal region 40a exhibiting an axially symmetric alignment. The convex portion 36 is made thinner by making the surface of one substrate on the liquid crystal layer 40 side higher than the other portion, thereby reducing the thickness of the liquid crystal layer 40.
Reduces the interaction between adjacent liquid crystal regions 40a of the liquid crystal molecules 42. The thickness of the liquid crystal layer 40 is such that the thickness (dout) of the liquid crystal layer 40 around the liquid crystal region 40 a is equal to the liquid crystal region (opening) 40.
a (din) which is smaller than the thickness (din) of the liquid crystal layer 40 in (a).
> Dout). Furthermore, 0.1 × din ≦ d
It is preferable to satisfy the relationship of out ≦ 0.8 × din. That is, when dout> 0.8 × din, the effect that the convex portion 36 weakens the interaction of the liquid crystal molecules between the liquid crystal regions 40a is not sufficient, and a single axially symmetric alignment region is formed for each liquid crystal region 40a. Can be difficult. further,
When 0.1 × din> dout, it may be difficult to inject a liquid crystal material by a normal vacuum injection method.

For example, by printing a convex portion at a desired position using a thermosetting resin with an ink-jet thin film forming apparatus, the convex portion can be formed at a very low cost. In addition, since a developing process for forming a convex portion at a desired position by a photo process is not required, the surface of the substrate is not contaminated with the developing solution.

(Control of the Position of the Center Axis of Axisymmetric Orientation) The position of the center axis of the axisymmetric alignment region generated when a predetermined voltage is applied greatly affects display quality. The relationship between the position and the display quality will be described. FIG.
As shown in FIG. 5A, when the central axis 44 is located at the center of a liquid crystal region (a case where one liquid crystal region is formed in a picture element region), as shown in FIG. Even if the display surface is observed by tilting the cell, all the liquid crystal regions look the same. On the other hand, as shown in FIG. 5B, when there is a liquid crystal region whose center axis is shifted from the center of the liquid crystal region, FIG.
As shown in (1), the liquid crystal region shifted from the center axis looks different from the other liquid crystal regions, so that a non-uniform (rough) display is obtained. This problem is particularly noticeable in halftone display.

The central axis of the axially symmetric alignment of the liquid crystal molecules is oriented perpendicular to the substrate in either a voltage applied state or a non-voltage applied state. Therefore, even when a voltage is applied to set the axis of the axially symmetric alignment central axis, the position of the axis of the axially symmetric alignment central axis is controlled by providing a region where the liquid crystal molecules maintain the vertical alignment state or a region without electrodes in the liquid crystal region. can do. The liquid crystal molecules in the axially symmetric alignment central axis region, in which the liquid crystal molecules maintain the vertical alignment state even when the voltage is applied, are stable without being affected by the electric field. The central axis of the axially symmetric orientation is formed in the above region. Further, by setting the size of the picture element region defined by the convex portion 36 to 100 μm × 100 μm or less, the deviation of the central axis does not affect the display quality.
Therefore, it can be expected that a region without an electrode and an axially symmetric alignment fixed layer are eliminated.

(Stabilization of Axisymmetric Alignment State of Liquid Crystal Molecules When Applying Axisymmetric Alignment Center Alignment Voltage) In the method of manufacturing a liquid crystal display device of the present invention, the liquid crystal molecules when applying an axisymmetric alignment centering center alignment voltage are applied. The step of storing the axially symmetric alignment state of the liquid crystal molecules in advance in the liquid crystal molecules includes forming the axis symmetric alignment state of the liquid crystal molecules in each liquid crystal region with good reproducibility when a predetermined voltage is applied. The axisymmetric alignment state can be stabilized. For example, in the following way:
The axisymmetric alignment state can be stored in the liquid crystal molecules in advance.

A liquid crystal cell is manufactured by bonding a pair of substrates each having a predetermined electrode or the like and having a convex portion on at least one substrate surface with the surface having the convex portion inside. A precursor mixture containing a liquid crystal material and a photocurable resin, which has been once made compatible and cooled to room temperature, is injected between a pair of substrates. The photocurable resin is cured by irradiating light while applying a voltage higher than a predetermined voltage. At this time, as the curing of the photocurable resin proceeds, a plurality of liquid crystal regions defined by the convex portions are formed. In addition, the voltage application causes the liquid crystal molecules in each liquid layer region to be axially symmetrically aligned, and a central axis of the liquid crystal molecule to be axially symmetrically aligned is formed substantially at the center of each liquid crystal region. In this state, the curing of the photocurable resin further proceeds, and an alignment fixed layer (composed of the liquid crystal molecules and the cured photocurable resin) in which the axially symmetric alignment is stored in the liquid crystal molecules is formed. Since the orientation of the liquid crystal molecules in the orientation fixing layer is fixed by the cured photocurable resin, it does not change even when the voltage is removed. The other liquid crystal molecules assume an axially symmetric alignment due to the interaction with the liquid crystal molecules of the alignment fixed layer.

In order to stabilize the axially symmetric alignment state of the liquid crystal molecules when a voltage is applied, in the step of storing the axially symmetric alignment state in the liquid crystal molecules, the liquid crystal molecules are tilted at a certain angle with respect to the substrate surface (tilt angle). It is important that you are.
That is, a voltage higher than the threshold voltage at which the liquid crystal molecules start to tilt with respect to the substrate surface, and lower than the saturation voltage at which the liquid crystal molecules tilt substantially parallel to the substrate surface (axis-symmetric alignment center axis alignment). By applying a voltage)
Axisymmetric alignment of liquid crystal molecules can be stabilized. The application of the axially symmetric alignment center axis setting voltage can be performed using an electrode for applying a voltage to the liquid crystal layer 40 in order to perform display. The axially symmetric orientation center axis voltage value is preferably an AC voltage having a threshold voltage of Vth and a voltage of Vth / 2 or more and a frequency of 1 Hz or more. When a DC voltage is applied, the precursor mixture may deteriorate. Note that a magnetic field may be applied instead of the axially symmetric alignment centering voltage, and a predetermined external field for tilting the liquid crystal molecules may be applied. In a normally black mode liquid crystal display device, the threshold voltage is defined as shown in FIG. 10% relative transmittance
Is a threshold voltage (Vth).

(Embodiment 1) In Embodiment 1, a first convex portion for aligning liquid crystal molecules and a second convex portion for defining a cell gap are formed by an ink-jet method. According to the known inkjet method, the positioning accuracy is extremely higher than that of the printing method.

A projection (first projection) is formed on a color filter substrate 74 by an ink jet type thin film forming apparatus having an ink head 70 and a plurality of emission nozzles 72 shown in FIG.
The protrusions and / or the second protrusions are referred to as protrusions). The color filter substrate (CF substrate) 74 has a glass substrate 76 and a color filter layer 78 formed thereon. The color filter layer 78 has R, G, and B coloring layers 78a and a black mask (BM: light shielding layer) 78b. The first protrusion and the second protrusion are formed on the black mask 78b. The CF substrate 74 is formed by a known method.

A method for manufacturing a CF substrate having a convex portion according to the present embodiment will be described in detail with reference to FIG.

On a BM 78b formed in a matrix on the CF substrate 74, a first grid-like
The projection 86a is formed by an ink-jet method using a resin material. As the resin material, a thermosetting polyimide material or an acrylic photosensitive material is used. The viscosity of the ejection material required to apply the inkjet method is about 1
It is preferably at most 00 cps. The positioning accuracy of the inkjet method is about ± 5 μm, and the minimum printing width (resolution) is about 10 μm or more. The grid-shaped wall-shaped first protrusions 86a are printed with a thickness of about 2.5 μm, dried on a hot plate at about 100 ° C., and dried at about 220 ° C.
Main firing in an oven at ℃.

The CF substrate 74 on which the first projection 86a is formed
A transparent electrode 88 is formed on almost the entire surface of the substrate by using ITO or the like. The formation of the transparent electrode 88 can be performed by a known method.

Next, at a position corresponding to the lattice-shaped first convex portion 86a on the transparent electrode 88, a column-shaped second convex portion 86b having a height of about 2.5 μm is formed discretely by using a resin material. It is formed in a pattern by an inkjet method. The control of the film thickness
It is preferable to control the discharge time by controlling the discharge amount of the resin material. 2nd convex part 8
6b is preferably formed at four corners of a liquid crystal region (typically, a pixel region) surrounded by the first convex portion 86a so as to maintain a cell gap. At this time, the first projection 8
6a> the width of the second convex portion. Further, as shown in FIG. 3, the height of the first convex portion 86a is din-dout, and the height of the second convex portion is dout. Second convex portion 86
The formation of b can be performed by the same method using the same material as the formation of the first protrusion 86a.

The transparent electrode 88 may be formed so as to cover the second convex portion 86b after forming the second convex portion 86b. Further, a transparent electrode 88 is formed on the color filter layer 78.
And the first convex portion 86a may be formed on the transparent electrode 88 (see FIG. 2).

The CF substrate 74 formed with the projections obtained as described above and a 5.6-type TFT substrate (also called an active matrix substrate) formed by a known method were bonded together using a sealant. . Note that a vertical alignment film (not shown) is formed on the surfaces of both substrates on the liquid crystal layer side. The formation of the vertical alignment film can be performed by a known method. In the obtained liquid crystal cell, the sum of the height of the first protrusion 86a and the height of the second protrusion 86b defines the cell gap (cell gap in the liquid crystal region: din in FIG. 3).

In the obtained liquid crystal cell, as a precursor mixture, a photocurable resin (for example, a compound represented by the following Chemical Formula 1) and a photopolymerization initiator (for example, I
rgacure 651) and a liquid crystal material having a negative dielectric anisotropy is injected. Further, a voltage near the threshold value of the liquid crystal material was applied, and the film was exposed to ultraviolet light to stabilize the axially symmetric alignment. By the axially symmetric alignment operation, an alignment fixed layer (not shown) is formed so as to cover the vertical alignment film (not shown).
As described above, in the obtained active matrix liquid crystal display device, as shown in FIGS. 3C and 3D, a stable axially symmetric alignment can be obtained when a voltage is applied.

[0063]

Embedded image According to the present embodiment, since the convex portions 86a and 86b are formed by the ink-jet method, the convex portions 86a and 86b are formed more than the conventional method.
Since the use efficiency of the material is high and the process is simplified, an axially symmetric liquid crystal cell can be obtained at lower cost than before.

The arrangement of the projections according to the present invention is not limited to the above-described arrangement described with reference to FIG. The projections may be formed to have a predetermined pattern so as to form a liquid crystal region regularly in association with the arrangement of the pixel regions. The convex portion may be formed as a line, a broken line, or a dot, or a combination thereof. Other examples of the arrangement of the convex portions used in the present invention are schematically shown in FIGS. In these figures, the first projection 86a and the second
Only the arrangement with the convex portion 86b is shown, and the same reference numerals as in FIG. 8 are used.

As shown in FIGS. 9A and 9B, the wall-shaped first convex portion 86a may be formed in a broken line shape, and the second convex portion 86b may be formed on a part thereof. As shown in FIG. 10, inside the first convex portion 86a formed in a rectangular lattice shape, two substantially square liquid crystal regions 4 are provided in a rectangular lattice.
The wall-shaped first convex portion 86a may be further formed so that 0a is formed. In addition, as shown in FIG. 11, the first convex portion 86a that divides the inside of the rectangular lattice into two regions may be formed continuously with the lattice-shaped first convex portion 86a. Further, as shown in FIGS. 12 and 13, the first convex portion 86a may be formed in a cross shape, and the second convex portion 86b may be formed at the intersection (center portion) of the cross. The first protrusions may be arranged so that the liquid crystal region 40a is regularly defined by the sides of the cross-shaped first protrusions 86a. The second convex portion 86b
The density at which is formed may be appropriately set in consideration of the application of the liquid crystal display device or the like so that the gap of the liquid crystal cell can be stably maintained.

In this embodiment, an example in which an active matrix type liquid crystal display device is manufactured using a TFT substrate has been described. However, a PALC (plasma address type liquid crystal display device) is manufactured using a plasma generating substrate instead of the TFT substrate. ) May be used. FIG. 14 shows an example of PALC.
Is shown schematically in FIG.

The PALC 200 teaches a liquid crystal layer including liquid crystal molecules 42 having negative dielectric anisotropy between the CF substrate 74 and the plasma generating substrate 90 shown in FIG.
Vertical alignment films 92a and 92b are formed on the surfaces of the CF substrate 74 and the plasma generation substrate 90 on the liquid crystal layer side, respectively. The plasma generating substrate 90 has a plasma channel 90 a surrounded by a glass substrate 94, a dielectric sheet 96 (about 50 μm in thickness), and a partition wall 97. The plasma channel 90a functions as a plurality of stripe-shaped address electrodes extending in a direction orthogonal to the transparent electrodes (stripe electrodes parallel to each other) of the CF substrate 74. An ionizable gas is sealed in the plasma channel 90a, and a plasma is generated by a voltage applied between the plasma generation electrodes 95. Known configurations can be widely applied as the plasma generating substrate.

Further, in the above-described example, the example in which the convex portion is formed on the CF substrate (counter substrate) has been described, but the first convex portion and the second convex portion may be formed on the TFT substrate or the plasma generating substrate. .

(Embodiment 2) In Embodiment 2, similarly to the lattice-like first convex portion 86a shown in FIG.
Is formed on the CF substrate 74. The second protrusion 86b in FIG. 8 is not formed. First convex portion 12
A liquid crystal display device using 6a as a spacer is manufactured.
The formation of the first protrusion 126a is only different in height,
It can be formed using a material similar to that of the first embodiment and a similar method. The vertical alignment film 1 is formed on the first convex portion 126a.
28 are formed in a conventional manner. The two-dimensional arrangement of the first convex portions 126a is not limited to that shown in FIG. 8 and may be the arrangement shown in FIGS.

Since the first convex portion 126a functions as a spacer while aligning the liquid crystal molecules in an axially symmetric manner, the liquid crystal region is completely surrounded by a pair of substrates facing the first convex portion 126a, and becomes a region independent of each other. . 9 to
In the other arrangement shown in FIG. 13, the liquid crystal material is completely or almost completely surrounded, and the liquid crystal material cannot be injected by the conventional vacuum injection method or the induction injection method, or the injection time may be extremely long. In the present embodiment, the injection of the precursor pair mixture (or only the liquid crystal material when stabilization of the axisymmetric alignment is not required) is performed by a printing method using a roll coater method.

For example, as shown in FIG.
The precursor is supplied onto the CF substrate 124 while rotating the roll 140 holding the precursor mixture 130 on the CF substrate 124 on which the 26a is formed. The use efficiency of the liquid crystal material can be improved by using the roll coater method.

Thereafter, as shown in FIG. 15B, a substrate 154 on which a sealant 152 made of a photocurable resin is screen-printed on a substrate 150 on which predetermined electrodes and the like are formed is replaced with the CF substrate. It is bonded to 124 in a vacuum. After the sealant 152 is cured by light irradiation, the photocurable resin in the precursor mixture is cured in the same manner as in the first embodiment to obtain a liquid crystal display device 300 having an axially symmetric liquid crystal region (FIG. (C)).

Further, instead of using the above-mentioned roll coater method, a liquid crystal material may be injected into a region defined by the convex portion by using an ink jet method.

The liquid crystal display device 300 according to the second embodiment has the following advantages in addition to the advantages of the first embodiment. In the liquid crystal display device 300, the first convex portion 126a is in close contact with both substrates, and the liquid crystal material does not flow between adjacent liquid crystal regions (typically, pixel regions). When standing, there is no change in cell thickness due to the weight of the liquid crystal material. Further, even when pressed from the outside, the liquid crystal material does not flow, so that the display quality does not change.

Further, when the first convex portion 126a is formed in the arrangement shown in FIGS. 9, 12 and 13 (when the second convex portion is not formed), the liquid crystal layer is a continuous one region. The precursor mixture may be injected by a conventional vacuum injection method or induction injection method.

The induction injection method will be described with reference to FIG. The CF substrate 124 'on which the first convex portion is formed and the TFT substrate or the plasma generating substrate 154' are bonded together while maintaining the cell gap at the first convex portion. Substrate 154 '
Has an inlet 154'a and an outlet 154'b. Each is connected to a vacuum pump via an injection jig 161 for an exhaust port and an injection jig 162 for an injection port with a buffer silicone rubber or an O-ring 163 interposed therebetween.
The liquid crystal material is supplied from the liquid crystal material bottle 131 to the liquid crystal material drain 167 of the injection jig 162 for the inlet.

Even when the first protrusion 126a is formed in the arrangement shown in FIGS. 9, 12 and 13, and the second protrusion is not formed, the first protrusion 12a is formed in the same manner as in the second embodiment.
6a is in close contact with both substrates, and there is no flow of liquid crystal material between adjacent liquid crystal regions. Therefore, when a large panel is set up vertically, there is no change in cell thickness due to the weight of the liquid crystal material. Also,
Even when pressed from the outside, the liquid crystal material does not flow, so that the display quality does not change.

[0078]

As described above, according to the present invention, the spin coating step and the photolithography step, which are required in the conventional manufacturing method, are not required, and the utilization efficiency of the material is increased. Therefore, a loss of a high-cost photosensitive resin can be reduced, and an expensive device or a photomask is not required, so that a liquid crystal display device having a wide viewing angle characteristic can be manufactured at a lower cost than before. In addition, the reliability of the display device does not decrease, such as a burn-in image due to contamination of the substrate by the developing solution in the developing process of the photolithography process.

According to the present invention, a projection having a desired film thickness is formed accurately and with high positional accuracy by using an ink jet method, and the utilization efficiency of a material is remarkably improved. further,
By injecting the liquid crystal material by a roll coater method, material loss can be reduced. Further, the display quality is not inferior to that of a liquid crystal panel manufactured through a conventional photolithography process.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of an ASM mode liquid crystal display device.

FIG. 2 is a diagram schematically showing a structure of one picture element region of an ASM mode liquid crystal display device.

FIG. 3 is a diagram for explaining the operation principle of the liquid crystal display device 100 of the present invention. (A) and (b) show the state when no voltage is applied, and (c) and (d) show the state when a predetermined voltage is applied.

FIG. 4 is a schematic diagram for explaining a phenomenon in which a central axis of axially symmetric alignment is controlled by a region without electrodes in the liquid crystal display device of the present invention.

FIG. 5 is a schematic diagram for explaining the relationship between the position of the central axis of the axially symmetric orientation and the display quality. (A) and (b) show the case observed from a direction perpendicular to the display surface, and (c) and (d) show the case observed from an oblique direction with respect to the display surface.

FIG. 6 is a diagram showing a definition of a threshold voltage.

FIG. 7 is a schematic diagram for explaining a liquid crystal injection method by an inkjet method.

FIG. 8 is a schematic view showing a color filter substrate having a convex portion according to the present invention. (A) is a top view, (b) is (a)
8b-8b 'cross-sectional view, and (c) is 8c-8c' of (a).
It is sectional drawing.

FIG. 9 is a schematic view showing another arrangement of the protrusions according to the present invention.

FIG. 10 is a schematic view showing another arrangement of the protrusions according to the present invention.

FIG. 11 is a schematic view showing another arrangement of the protrusions according to the present invention.

FIG. 12 is a schematic view showing another arrangement of the protrusions according to the present invention.

FIG. 13 is a schematic view showing another arrangement of the protrusions according to the present invention.

FIG. 14 is a schematic view showing PALC according to the present invention.

FIG. 15 is a schematic diagram for explaining a liquid crystal material injection method using a roll coater method.

FIG. 16 is a schematic diagram for explaining a liquid crystal material induction injection method.

[Explanation of symbols]

 31, 33 Transparent electrode 32, 34 Substrate 35 Opening (region without electrode) 36 Convex portion 38a, 38b Vertical alignment layer 40 Liquid crystal layer 40a Liquid crystal region 42 Liquid crystal molecule 44 Symmetry axis

Claims (10)

[Claims] A pair of substrates each having an electrode;
A liquid crystal layer sandwiched between the pair of substrates, and at least one of the pair of substrates has a convex portion on a surface on the liquid crystal layer side, and the liquid crystal layer includes a plurality of liquid crystals defined by the convex portion. Liquid crystal molecules of the liquid crystal layer have a positive or negative dielectric anisotropy, the liquid crystal molecules are oriented substantially perpendicular to the surfaces of the pair of substrates during black display, and the liquid crystal molecules during white display. A method for manufacturing a liquid crystal display device, in which liquid crystal molecules are aligned in an axially symmetric manner for each of the plurality of liquid crystal regions, comprising: providing a pair of substrates each having an electrode; and forming the electrodes on at least one of the substrates. Selectively applying a first coating liquid containing a curable resin material to the surface by using an inkjet method, and drying and curing the first coating liquid selectively applied to form a convex portion. The forming step and the surface on which the electrode is formed face each other. Thus, a method of manufacturing a liquid crystal display device, comprising: bonding a pair of substrates; and supplying a liquid crystal material having positive or negative dielectric anisotropy between the pair of substrates. 2. In the first application liquid applying step, a discharge amount of the first application liquid is controlled based on an application time.
A method for manufacturing the liquid crystal display device according to claim 1. 3. The method for manufacturing a liquid crystal display device according to claim 1, wherein, in the bonding step, the pair of substrates are bonded to each other using the convex portion as a spacer. 4. The method according to claim 1, wherein in the first application liquid application step, the first application liquid is simultaneously applied to different positions from a plurality of nozzles. 5. In the first application liquid applying step, the first application liquid is provided on a surface of the at least one substrate.
The method according to claim 1, wherein the liquid crystal display device is provided in a regular pattern corresponding to the picture elements. 6. The first coating liquid applying step, wherein the first coating liquid is applied on a surface of the at least one substrate.
The method for manufacturing a liquid crystal display device according to claim 5, wherein the liquid crystal display device is provided in a linear, broken, or dotted shape. 7. In the first application liquid applying step, the first application liquid is provided on a surface of the at least one substrate.
The method for manufacturing a liquid crystal display device according to claim 1, wherein the liquid crystal display device is provided in a lattice shape at a position corresponding to a periphery of a picture element. 8. The step of supplying a liquid crystal material is a step of supplying a precursor mixture containing a liquid crystal material and a photocurable resin, and the step of heating the precursor mixture to make it compatible. And irradiating the precursor mixture in the compatibilized state with light while applying a voltage equal to or higher than a predetermined voltage to cure the photocurable resin, and the plurality of liquid crystals defined by the protrusions. 2. The method according to claim 1, further comprising: forming a central axis of the axially symmetric alignment of the liquid crystal molecules at a substantially central portion of each of the regions, and forming an alignment fixed layer in which the axially symmetric alignment is stored in the liquid crystal molecules. A method for manufacturing a liquid crystal display device. 9. The liquid crystal material is supplied by a roll coater method or an ink jet method into a region defined by the protrusions formed on the surface of the at least one substrate, and thereafter, the pair of substrates are bonded to each other. The method for manufacturing a liquid crystal display device according to claim 1, wherein: 10. A step of selectively supplying a second coating liquid containing a horizontal alignment material or a vertical alignment material to surfaces of the pair of substrates on which the electrodes are formed, and drying the second coating liquid. The method of claim 1, further comprising: forming a horizontal alignment layer or a vertical alignment layer.