JPH1020301A - Production of liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To embody a process for producing a liquid crystal display device which is nearly independently controllable in hue and lightness without using color filters, is excellent in assigning intensity levels and has excellent optical efficiency. SOLUTION: This production process produces the liquid crystal display device of a matrix type consisting of plural unit cells which have at least polarizing plates 201a, 201b, phase difference plates or phase difference films 202a, 202b, and liquid crystal layers 207, are formed by holding the liquid crystal layer layers 207 on the opposite inner sides of a first substrate 203a and second substrate 203b having electrodes 204, 205a to 205c, obtain colored light by a double refraction effect and constitute many pixels. At this time, a stage for applying a soln. of at least >=1 kinds of liquid crystalline materials by each unit cell on the inside surfaces of the substrates, a stage for orienting these liquid crystalline materials, a stage for forming thin films by curing the soln. and a stage for finely working the thin films by each of the respective unit cells are executed, by which the phase difference values and delay phase axis directions of the phase difference films installed at the respective unit cells are varied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a matrix type liquid crystal display device for obtaining colored light by a birefringence effect.

[0002]

2. Description of the Related Art A liquid crystal display device is a display characterized by being thin, lightweight, and low in power consumption. It is widely used as a display device for word processors, personal computers, TVs, and the like. There has been remarkable progress in equipment.

The liquid crystal display device for obtaining a color image includes a type using a color filter and a type for obtaining a color display by a birefringence effect. At present, the former type using a color filter is generally widely used, but the light utilization efficiency is low due to light absorption of the color filter. Therefore, it is not used as it is in a reflection type color liquid crystal display device. On the other hand, as a method of obtaining colored light by the latter birefringence effect, ECB (Electrically Controlled Bire
fringence (field effect type birefringence mode) method, and a plurality of colors can be displayed in the same cell without using a color filter, so that light use efficiency is high and bright color display is possible. . Therefore, the ECB type liquid crystal display device is promising not only as a transmission type liquid crystal display device but also as a reflection type liquid crystal display device.

[0004] Conventionally, as a color liquid crystal display device of the ECB system, there is one described in, for example, JP-A-6-175125. FIG. 2 shows a conceptual diagram of the structure of the liquid crystal display device according to the manufacturing method.

[0005] A pair of transparent substrates 2 sandwiching the liquid crystal layer 207
03a. The polarizing plate 201a, 2
01b and retardation plates 202a and 202b are provided.
Segment electrodes 205a, 205b, and 205c are provided on the opposing inner surface of one transparent substrate 203b, and a common electrode 204 is provided on the opposing inner surface of the transparent substrate 203a. An alignment film 20 is formed on each of the electrode forming surfaces of both substrates.
6a and 206b are formed to control the alignment direction and tilt angle of liquid crystal molecules.

In such a configuration, the alignment state of the liquid crystal molecules changes according to the magnitude of the voltage applied between the electrodes of the two substrates of the liquid crystal cell, and the retardation of the liquid crystal layer changes. Therefore, the change state of the light passing through the liquid crystal layer can be changed, and the color of the light passing through the exit-side polarizing plate can be changed. In the ECB method, a liquid crystal cell colored white or black without applying a voltage is changed to a white (black) color by a change in voltage.
The display color changes from red to blue to green.

[0007]

However, the conventional ECB
As described above, since the display color is changed by the voltage in the liquid crystal display device of the system, the change in hue and the change in lightness are not independent, and it is very difficult to display a gradation. In addition, there is a problem that an image looks strange because it passes through various colors on the way to reach a predetermined color depending on a voltage, and it is difficult to realize a display with high light use efficiency, low power consumption, and full color display. Was.

On the other hand, in a matrix type ECB type liquid crystal display device including a large number of pixels, a plurality of units whose luminance monotonously changes from white or black to a reference color with a voltage while maintaining substantially the same hue. An invention of a liquid crystal display device configured to be divided into cells is disclosed in Japanese Patent Application No. 8-20852. As a result, a liquid crystal display device having excellent gradation display performance in which hue and brightness can be controlled independently while maintaining the characteristics of the ECB method without using a color filter can be obtained. However, there has been no concrete manufacturing method to achieve this.

The present invention maintains the features of the above-mentioned ECB system which does not use a color filter which is a new liquid crystal display device,
An object of the present invention is to realize a method of manufacturing a liquid crystal display device having excellent gradation display performance in which hue and brightness can be controlled independently.

[0010]

In order to achieve the above object, the present invention provides a matrix type ECB comprising a large number of pixels.
A unit required for a liquid crystal display device in which one pixel is divided into a plurality of unit cells in which luminance changes monotonically with voltage between white or black and a reference color while maintaining substantially the same hue while maintaining the same hue. This is a manufacturing method that can form a retardation film having different performance for each cell.

Specifically, the present invention provides at least a polarizing plate, a retardation film or a retardation film, and a liquid crystal layer, and the liquid crystal layer is provided inside a first substrate having electrodes and a second substrate opposed to each other. The following solution is taken in a matrix type liquid crystal display device having a plurality of unit cells constituting a large number of pixels, in which a layer is sandwiched and colored light is obtained by a birefringence effect.

That is, a first solution of the present invention comprises a step of applying a solution of at least one kind of liquid crystalline material to the inner surface of one of the substrates for each unit cell, and a step of aligning the liquid crystalline material. Curing the solution to form a thin film, and finely processing the formed thin film for each unit cell, so that the retardation value of the retardation film installed in each unit cell can be reduced. It is characterized in that the phase axes are formed so as to be different from each other.

[0013] The second solution of the present invention is to provide a solution containing at least one or more types of photopolymerizable polymer monomers for each of the unit cells on the inner surface of one of the substrates based on the above-mentioned premise. A step of irradiating the photopolymerizable polymer monomer with polarized ultraviolet rays having different polarization directions for each unit cell to orient and polymerize and cure to form a thin film; and a step of finely processing the formed thin film for each unit cell. And the retardation film and the slow axis direction of the retardation film provided in each unit cell are formed so as to be different from each other.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a conceptual diagram of a configuration of a liquid crystal device for describing a method of manufacturing a liquid crystal display device according to a first embodiment of the present invention.

In FIG. 1, polarizing plates 201a and 201b and retardation plates 202a and 202b are provided on opposing outer surfaces of a pair of transparent substrates 203a and 203b sandwiching a liquid crystal layer 207. The segment electrodes 205a, 205b, and 205c are provided on the opposing inner surface of one of the transparent substrates 203b.
Further, an alignment film 206b was formed on the electrode, and rubbed in a predetermined direction with a rayon cloth or the like. In contrast,
A unit cell system 109a corresponding to the reference color red and a unit cell system 1 corresponding to the reference color green are provided on the opposed inner surface of the transparent substrate 203a.
A plurality of pixel systems 110 each including three unit cells 09b and a unit cell system 109c corresponding to the reference color blue are provided.

Next, a unit cell system 109 corresponding to the reference color red
The step of forming a predetermined retardation film 108a corresponding to the reference color red on a will be described with reference to FIG. Referring to FIG. 3A, an alignment film 310 was formed on the inner surface of the transparent substrate 203a, and rubbed in a predetermined direction with a rayon cloth or the like. A predetermined amount of a solution of a first liquid crystal material, for example, a mixed monomer (320) containing a liquid crystal monomer having a UV-polymerization property, for example, a liquid crystal diacrylate monomer, was applied by a method such as spinner or printing.

By the above-mentioned steps, the ultraviolet-polymerizable liquid crystalline monomer was oriented along the treated orientation direction.
Next, the aligned UV-polymerizable liquid crystalline monomer (3)
20) is irradiated with ultraviolet light 302 and polymerized and cured to form a thin film 320 having a predetermined thickness. The oriented liquid crystal monomer thin film 320 forms a first retardation film having a refractive index anisotropy Δn, a retardation value obtained from a predetermined thickness, and a slow axis.

Next, in FIG. 3B, in order to divide the formed first retardation film into a unit cell system 109a corresponding to the reference color red, a photoresist 311 is added to the retardation film.
Exposure and development were carried out in a normal photolithography process using a photomask, and all the remaining thin films 321 were removed by dry etching for fine processing except for the retardation films 108a on the plurality of unit cells 109a. In this way, a retardation film 108a having a predetermined retardation value and a slow axis was formed in a plurality of unit cell systems 109a corresponding to the reference color red.

Next, predetermined phase difference films 108b and 108c corresponding to the reference colors green and blue are respectively provided on a plurality of unit cell systems 109b and 109c corresponding to the reference colors green and blue by the second and third ultraviolet polymerized liquid crystals. It forms by the same process as the above using a hydrophilic monomer.

As shown in FIG. 1, a plurality of unit cell systems corresponding to three reference colors on the transparent substrate 203a have different retardation values and retardation films 10 of different retardation axis directions as described above.
8a, b, and c, the common electrode 204,
A panel was manufactured by forming an alignment film 206a, performing a rubbing treatment, and sandwiching a liquid crystal layer 207 having a transparent substrate 203a, b and having a homogeneous alignment with a gap of 5 microns.

Under the transmission of white light, the electrodes 204 and 205a, 205b, 205c of the panel manufactured as shown in FIG.
Is driven by applying a predetermined voltage to the unit cell system 109.
a, 109b, and 109c developed the reference colors red, green, and blue. Further, although the driving voltage was changed for each unit cell, the brightness changed, and the hue hardly changed. Although the entire panel, which is a group of a plurality of pixels, was driven, a high-quality color liquid crystal display device capable of controlling the brightness and hue almost independently could be manufactured.

In the above, a liquid crystalline monomer containing a liquid crystalline diacrylate monomer is used, but another type of liquid crystalline monomer may be used as long as it can form a retardation film. Although the first, second and third liquid crystalline polymers are used in the above description, at least one kind of material may be used.

In the above, the solution of the liquid crystalline monomer was oriented by the rubbed alignment film. However, the solution was also oriented by the alignment film irradiated with polarized ultraviolet light. Also. After applying the liquid crystalline polymer, the solution could be oriented even when a magnetic field was applied in a predetermined direction. Orientation can also be performed by applying an electric field.

Further, in the above, an ultraviolet-polymerizable liquid crystal monomer was used as a liquid crystal material and cured by irradiation with ultraviolet light to form a thin film. However, as a liquid crystal material, an ordinary heated solution of a liquid crystal polymer was used. May be. The retardation film could be formed in the unit cell corresponding to each reference color even by using a process of applying and orienting the liquid crystalline polymer, and then thermally cooling and curing to form a thin film and performing a fine processing.

In the above description, the phase difference film cured for fine processing is exposed and developed in a usual photolithography process using a photoresist and a photomask to perform dry etching, but wet etching may be performed. (Embodiment 2) FIG. 4 is a conceptual diagram of a configuration of a liquid crystal device for describing a method of manufacturing a liquid crystal display device according to a second embodiment of the present invention.

In FIG. 4, polarizing plates 201a and 201b and retardation plates 202a and 202b are provided on the opposing outer surfaces of a pair of transparent substrates 203a and 203b sandwiching a liquid crystal layer 207. Segment electrodes 205a, 205b, and 205c are provided on the opposing inner surface of one transparent substrate 203b.
Further, an alignment film 206b is formed and a rubbing alignment process is performed. On the other hand, three unit cells of a unit cell system 409a corresponding to the reference color red, a unit cell system 409b corresponding to the reference color green, and a unit cell system 409c corresponding to the reference color blue are provided on the opposed inner surface of the transparent substrate 203a. Pixel system 410 composed of
Are provided.

A process of forming and manufacturing a predetermined retardation film 408a corresponding to the reference color red in the unit cell system 409a corresponding to the reference color red on the transparent substrate 203a will be described with reference to FIG.

In FIG. 5, a predetermined amount of a solution of a first photopolymerizable polymer monomer, for example, PVMC (vinyl 4-methoxycinnamate) is applied onto the inner surface of the transparent substrate 203a by a method such as spinner or printing. The polarized ultraviolet light 50 in the deflection direction corresponding to the reference color red is passed through the photomask 511 to the unit cell system 409a corresponding to the reference color red in the applied coating liquid of the photopolymerizable polymer monomer.
Irradiate 2. As a result, the photopolymerizable polymer monomer was oriented by the deflecting light and, at the same time, the portion irradiated with ultraviolet light was polymerized and cured to form a thin film. The non-irradiated portion 512 that has not been irradiated with the polarized ultraviolet rays does not cure, is washed away with a solvent and finely processed, and a predetermined phase difference value is added to the portion of the unit cell system 409a.
A retardation film 408a having a slow axis was formed.

Next, as shown in FIG.
Multiple unit cell systems 4 corresponding to the reference colors green and blue on the inner surface
Phase difference films 408b and 408c having a phase difference value and a slow axis corresponding to the reference colors green and blue, respectively, are formed at 09b and 409c in substantially the same steps as above.

Next, as shown in FIG. 4, a common electrode 204 and an alignment film 206a are formed in a normal process, rubbing is performed, and a liquid crystal 207 that has been homogeneously aligned on the transparent substrates 203a and 203b with a gap of 5 μm is narrowed. To make a panel.

The electrodes 204 and 205a, 205b, 20 of the panel manufactured as shown in FIG.
As a result of applying a predetermined voltage to 5c and driving it, the unit cell system 40
9a, 409b, and 409c exhibited the reference colors red, green, and blue. Further, although the driving voltage was changed for each unit cell, the brightness changed, and the hue hardly changed. Although the entire panel, which is a group of a plurality of pixels, was driven, a liquid crystal display device excellent in gradation display in which brightness and hue could be controlled almost independently could be manufactured.

In the first and second embodiments described above,
In the step of curing a solution of a liquid crystal material, a solution of a liquid crystal monomer or a photopolymerizable polymer monomer to form a thin film, the phase difference value can be optimized by changing the heating holding temperature and time for each unit cell.

Further, in the above, the thickness of the retardation film formed by curing the solution of the liquid crystalline monomer or the photopolymerizable polymer monomer is changed, and as shown in FIG.
a, 409b, and 409c, the phase difference films 408a, 408 having different film thicknesses so as to obtain a predetermined phase difference value.
b, 408c could be formed.

In the above, a thin film formed from a liquid crystal monomer or a photopolymerizable polymer monomer can be formed by a dry etching or wet etching step as required as a fine processing method for each unit cell.

In the above description, the phase difference film formed for each unit cell in the first and second embodiments is formed from a single liquid crystalline monomer or a single photopolymerizable polymer monomer. As a type of the retardation film to be formed, a combination of the above two types of retardation films could be formed.

In the above description, as shown in FIG. 7, one of the reflection electrodes 705a, 705b and 705c of the two substrate electrodes is constituted by a light reflection electrode of Al or the like, and each of the unit cells 109a, b, phase difference film 108 corresponding to c
a, b, and c were formed, alignment rubbing was performed, and a liquid crystal was sandwiched to produce a reflective liquid crystal display device as shown in FIG. When a voltage was applied to each electrode to drive it, the drive voltage was changed for each unit cell, but the brightness changed, and there was almost no change in hue. Although the entire panel, which is a group of a plurality of pixels, was driven, it was possible to manufacture a reflective color liquid crystal display device having high light efficiency and capable of controlling the brightness and hue almost independently of each other and having good gradation.

The above-mentioned predetermined constitutional conditions of the liquid crystal display device according to the present invention are as follows. That is, the pixel has (1) an angle formed by a transmission axis of the polarizing plate with respect to a fixed reference axis, (2) a phase difference of the phase difference film, (3) an angle formed by a slow axis of the phase difference film, 4) the retardation of the liquid crystal layer,
(5) the orientation direction of each liquid crystal molecule on the first and second substrate surfaces,
It consists of multiple unit cells with different combinations of tilt angles,
(1) to (4) so that the liquid crystal display device constituted by these pixels can display white, black, reference color, and halftone display of the same hue.
This is the condition under which the combination of (5) is selected and determined.

In the present invention, the alignment state of the liquid crystal layer is defined as a homogeneous alignment, but a homeotropic alignment, a hybrid alignment and the like can be selected by a combination of light control.

The manufacturing method of the present invention can be similarly applied to any of a simple matrix type, an active matrix type liquid crystal display device such as TFT and MIM, and a reflection type liquid crystal display device of those types.

[0040]

As described above, according to the present invention, it is possible to manufacture a liquid crystal display device which can control hue and lightness almost independently without using a color filter, is excellent in gradation display, and has high light efficiency. An advantageous effect is obtained.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating a configuration of a liquid crystal display device according to a first embodiment of the present invention, which is manufactured by a manufacturing method.

FIG. 2 is a conceptual diagram showing a configuration of a conventional liquid crystal display device by a manufacturing method.

FIG. 3 is a conceptual diagram of a retardation film forming process by a method of manufacturing a liquid crystal display device according to the first embodiment of the present invention.

FIG. 4 is a conceptual diagram illustrating a configuration of a liquid crystal display device according to a second embodiment of the present invention by a manufacturing method.

FIG. 5 is a conceptual diagram of a retardation film forming process by a method of manufacturing a liquid crystal display device according to a second embodiment of the present invention.

FIG. 6 is a conceptual diagram illustrating a configuration of a liquid crystal display device according to another embodiment of the present invention, which is manufactured by a manufacturing method.

FIG. 7 is a conceptual diagram showing a configuration of a reflection type by a method of manufacturing a liquid crystal display device according to another embodiment of the present invention.

[Explanation of symbols]

201a, 201b, polarizing plates 202a, 202b, retardation plates 203a, 203b, transparent substrates 204, ... common electrodes 205a, 205b, 205c, segment electrodes 207, ... Liquid crystal layers 206a, 206b alignment films 108a, 108b, 108c retardation films 109a, 109b, 109c unit cells 110 ... pixels 302 ... ultraviolet light 310 ... ...... Alignment film 311 Photoresist 320 Thin film 321 Thin film 408a, 408b, 408c Phase difference film 409a , 409b, 409c, unit cell 410, pixel 502, polarized ultraviolet light 511, photomask 512, etc.
... Non-irradiated parts 705a, 705b, 705c-reflective electrode

Claims (10)

[Claims] 1. A first substrate and a second substrate having at least a polarizing plate, a retardation film or a retardation film, electrodes, and a liquid crystal sandwiched between opposing inner sides of the first and second substrates. A method for producing a matrix-type liquid crystal display device comprising a plurality of unit cells constituting a large number of pixels, the colored light being obtained by a birefringence effect. A step of applying a solution of one or more liquid crystal materials, a step of orienting the liquid crystal material, a step of curing the solution to form a thin film, and finely processing the formed thin film for each unit cell A method for manufacturing a liquid crystal display device, comprising a step of forming a retardation film and a retardation axis direction of a retardation film provided in each unit cell so as to have different retardation axis directions. 2. The method according to claim 1, wherein the step of aligning the liquid crystalline material comprises a step of forming an alignment film or performing an alignment treatment by applying a magnetic field or an electric field such that at least the surface of each unit cell has a different alignment direction. Claim 1
The manufacturing method of the liquid crystal display device according to the above. 3. The method according to claim 1, wherein the solution of the liquid crystalline material is an ultraviolet-polymerizable liquid crystalline monomer, and the step of curing the solution to form a thin film includes the step of irradiating the solution with ultraviolet rays. Item 3. A method for manufacturing a liquid crystal display device according to item 1 or 2. 4. The step of forming a thin film by curing the liquid crystalline polymer, wherein the solution of the liquid crystalline material is a liquid crystalline polymer, and the step of thermally cooling the solution to form a thin film. The method for manufacturing a liquid crystal display device according to claim 1, wherein: 5. A first substrate and a second substrate having at least a polarizing plate, a retardation plate or a retardation film, electrodes, and a liquid crystal sandwiched between the first and second substrates facing each other. A method for producing a matrix-type liquid crystal display device comprising a plurality of unit cells constituting a large number of pixels, the colored light being obtained by a birefringence effect. Applying a solution containing at least one kind of photopolymerizable polymer monomer, and irradiating the photopolymerizable polymer monomer with polarized ultraviolet rays having different deflection directions for each unit cell to align and polymerize and cure the thin film. Forming, and a step of finely processing the formed thin film for each unit cell, wherein the phase difference value of the retardation film installed in each unit cell, the slow axis direction is formed differently. Characteristic liquid crystal display device manufacturing method 6. The method according to claim 1, wherein the step of curing the solution to form a thin film includes the step of changing the heating temperature and / or time of the solution for each unit cell.
6. The method for manufacturing a liquid crystal display device according to 4 or 5. 7. The method according to claim 1, further comprising the step of changing the thickness of the retardation film formed for each unit cell to form the retardation film so that the retardation value is different and the direction of the slow axis is different. The method for manufacturing a liquid crystal display device according to claim 1, 2, 3, 4, 5, or 6. 8. The method according to claim 1, wherein the step of finely processing the formed thin film for each unit cell includes a step of dry etching or wet etching using a fine mask. 8. The method for producing a liquid crystal display device according to 5, 6, or 7. 9. The method according to claim 1, wherein the type of the retardation film formed for each unit cell is formed from a combination of a solution containing the liquid crystalline monomer and the photopolymerizable polymer monomer. 1, 2, 3, 4, 5, 6,
9. The method for manufacturing a liquid crystal display device according to 7 or 8. 10. The method according to claim 1, wherein one of said first and second substrates having said electrodes is constituted by a light reflecting electrode. 10. The method for manufacturing a liquid crystal display device according to 7, 8, or 9.