JP2001318373A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device having high light shielding function and higher display quality though the device is produced at a low cost. SOLUTION: In the device, polarization function films 3, 13 are formed in contact with a liquid crystal layer 20 above the substrates 1, 11 and transparent electrodes 2, 12, respectively. The polarization function films 3, 13 comprises a liquid crystal polymer containing a dichroic dye. In the pixel region of the polarization function films 3, 13, the liquid crystal polymer and the dichroic dye are uniaxially aligned to exhibit a polarizing function and an aligning function for the liquid crystal. In particular, by irradiating the nonpixel region of the polarization function films 3, 13 with IR laser light, the alignment of the liquid crystal polymer and dichroic dye is disturbed to show a light-shielding function.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a liquid crystal display device, and more particularly, to an improvement in a light shielding means formed to prevent light leakage from a non-pixel region.

[0002]

2. Description of the Related Art In a liquid crystal display device, it is necessary to shield light from the non-pixel region in order to prevent light leakage from the non-pixel region. In order to shield the non-pixel region from light, a technique for separately forming a light shielding layer called a black matrix is well known. By providing this black matrix, light leakage from the non-pixel region is suitably prevented.

[0003]

However, since the provision of the above-mentioned black matrix causes an increase in cost, development of a low-cost material suitable for the black matrix is required.

On the other hand, by forming this black matrix, various inconveniences caused by the occurrence of steps between the pixel region and the non-pixel region of the liquid crystal display device cannot be ignored. For example, this step causes a problem in that the alignment is disturbed when the alignment control is performed on the alignment film, and thus the display quality of the liquid crystal display device is deteriorated. In order to avoid such a problem, there is a method of forming a means for flattening the step, and the like. However, when this is formed, an increase in the number of work steps and an increase in cost are inevitable. .

[0005] In any case, it is desired to develop a light shielding means capable of avoiding various inconveniences caused by the formation of the black matrix. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a liquid crystal display device which has a high light shielding function at low cost and can improve display quality.

[0006]

The means for achieving the above object and the effects thereof will be described below. The gist of the invention described in claim 1 is to provide a liquid crystal display device including a polarizing function film provided with a light blocking function corresponding to each non-pixel region.

According to the above configuration, unlike the formation of the black matrix, by providing the light-blocking function to the polarizing function film, it is possible to preferably avoid the problem that a step occurs when forming the light-blocking means. become. Note that this polarizing function film is a means normally provided in a liquid crystal display device in order to make a change in optical characteristics of light caused by transmission of a liquid crystal obvious, and therefore, a polarizing means is separately provided from the polarizing function film. It is not necessary to provide.

According to a second aspect of the present invention, in the first aspect of the invention, the polarizing function film includes a dichroic dye, and the light shielding function is such that the arrangement of the dichroic dye is selectively disturbed. The gist is to be granted by

Usually, the polarizing means is formed by orienting a polymer containing a dichroic dye and also orienting the dichroic dye. In this regard, according to the above configuration, in each non-pixel region, the arrangement of the dichroic dye used in the polarization function film is disturbed, so that the region can be suitably shielded from light.

A third aspect of the invention is based on the second aspect, wherein the polarizing function film further includes a liquid crystalline polymer and is formed in contact with a liquid crystal layer. According to the above configuration, since the polarizing function film according to claim 2 further includes a liquid crystalline polymer, the polarizing function film can have a function as an alignment film.

In the case where the polarizing means is attached to the outside of the liquid crystal cell via an adhesive in the liquid crystal display device, the sticking is performed so that air bubbles and foreign matter are not trapped between the liquid crystal cell and the polarizing means. Therefore, the attaching work is a burden on the manufacturing process. In this regard, according to the above configuration, the polarization function film also has the function of the alignment film, and is formed in the liquid crystal cell, so that the above-described load in the manufacturing process is reduced.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 shows a first embodiment in which a liquid crystal display device according to the present invention is applied to a simple matrix type monochrome liquid crystal display device.
And FIG.

FIG. 1 is a sectional view of a liquid crystal display device according to the present embodiment. As shown in FIG. 1, this liquid crystal display device has an ITO (Indi) having a thickness of 1000 ° on a plastic substrate 1 made of polyether sulfone.
um Tin Oxide) is formed in a stripe shape. Further, on this transparent electrode 2, 500
The polarizing function film 3 having a thickness of Å is formed in contact with the liquid crystal layer 20. The polarization function film 3 has a polarization function of selectively transmitting only light in a predetermined direction and a liquid crystal layer 20.
And a function of aligning the liquid crystal molecules.

On the other hand, the plastic substrate 11 made of polyethersulfone facing the substrate 1
ITO (Indium Tin Oxide) with a thickness of 2,000 mm
Is formed. The transparent electrode 12 is formed in a stripe shape like the transparent electrode 2, and is arranged so as to be orthogonal to the transparent electrode 2. Further, on the substrate 11 and the transparent electrode 12, a polarizing function film 13 having a thickness of 500 ° is formed. The polarization function film 13 also has a polarization function of selectively transmitting only light in a predetermined direction and a function of aligning liquid crystal molecules of the liquid crystal layer 20.

The substrate 1 and the substrate 11 are formed of a sealing resin 30 made of an ultraviolet-curable acrylic polymer resin and a spacer 3 made of bead-shaped silica having a diameter of 4 μm.
1 and a liquid crystal layer 20 composed of a nematic liquid crystal are bonded together to form a liquid crystal display device. In addition, the polarization direction of the polarizing function film 3 formed on the substrate 1 side and the substrate 1
The polarization direction of the polarization function film 13 formed on one side is 90
It is arranged with a twist of °. That is, the liquid crystal display device of the present embodiment is a twisted nematic liquid crystal display device in which the liquid crystal molecules of the liquid crystal layer 20 are twisted by 90 ° between the polarization functional films 3 and 13.

The polarizing function films 3 and 13 are obtained by mixing about 5% of an azo dichroic dye into a polysiloxane liquid crystal polymer material. Since the liquid crystal polymer has a configuration in which the mesogenic groups of the liquid crystalline polymer are oriented in a predetermined direction, the alignment of the liquid crystal molecules of the liquid crystal layer 20 is controlled along the orientation direction. In addition, the dichroic dye is oriented along the mesogen group, so that the absorption axes are aligned in the same direction, and it has a polarizing function.

In the liquid crystal display device of the present embodiment, the polarization function films 3 and 13 not only have an alignment function and a polarization function, but also have a function of preventing light leakage from a non-pixel region. ing. Hereinafter, the configuration and the light shielding function of these polarization functional films 3 and 13 will be described by taking the polarization functional film 13 shown in FIG. 2 as an example.

FIG. 2A is a perspective view of the polarizing function film 13 formed on the substrate 11 side. As shown in FIG. 2A, the polarization functional film 13 includes a pixel region 13a and a non-pixel region 13b. Here, the pixel region 13 a is a region formed when the transparent electrode 2 and the transparent electrode 12 are respectively projected on the polarization function film 13.
The area at the intersection of these two areas is matched.

The pixel region 13a has a structure in which the liquid crystal polymer and the dichroic dye described above are regularly arranged to have both a polarization function and a liquid crystal alignment function. Therefore, the alignment of the liquid crystal molecules of the liquid crystal layer 20 is controlled by the pixel region 13a. Further, light incident on the substrate 11 side is selectively transmitted through the pixel region 13a, so that light emitted from the pixel region 13a is polarized in a predetermined direction.

On the other hand, in the non-pixel region 13b, the above-mentioned liquid crystalline polymer and dichroic dye are randomly formed,
It has a configuration having a light blocking function. Therefore, such a problem that light passes through the non-pixel region 13b and leaks into the pixel region 13a can be suitably solved.

Next, a method of forming the polarization function film 13 will be described. As shown in FIG. 2B, first, the liquid crystalline polymer containing the above-described dichroic dye is applied and formed on the substrate 11 in a predetermined direction using a roller, a squeegee, or the like. At this time, the mesogenic group of the liquid crystalline polymer is oriented in the application direction, and the dichroic dye is oriented along the mesogenic group as described above. Therefore, at this time, the film 3 ′ formed by application is a film having both a polarizing function and a function of aligning the liquid crystal. In forming the film 3 ', a technique according to the technique described in JP-A-2-101431 can be used.

Next, the non-pixel region 1 shown in FIG.
3b only, wavelength 10 μm, energy density 0.01 to
Irradiate an infrared laser of 0.1 / cm ² . The irradiation of the infrared laser heats the liquid crystalline polymer in the non-pixel region 13b to 110 °. Therefore, in the non-pixel region 13b, the orientation of the liquid crystalline polymer is disordered,
Along with this, the orientation of the dichroic dye also becomes disordered. Therefore, the dichroic dye in the non-pixel region 13b loses the order of the absorption axis and absorbs light in all directions, and thus has a light shielding property.

The above-mentioned disordering of the orientation of the liquid crystalline polymer is carried out by increasing the glass-nematic liquid crystal transition temperature of the liquid crystalline polymer in consideration of the transition temperature of 90 °. Will be

When the contrast of the liquid crystal display device according to the present embodiment using the polarization functional films 3 and 13 formed through the above steps was measured, a value of “200” was obtained. This value is about 10% higher than that of a conventional liquid crystal display device using a black matrix.

According to this embodiment described above, the following effects can be obtained. (1) By providing the light blocking function to the non-display areas of the polarization function films 3 and 13, it is not necessary to newly provide a black matrix, and the step caused by this black matrix is preferably eliminated.

(2) A liquid crystal polymer containing a dichroic dye is used as a material for the polarizing function films 3 and 13, and the arrangement of the dichroic dye is disordered, so that light-shielding properties can be easily provided. Can be.

(3) By disposing the polarizing function film 3 in contact with the liquid crystal layer 20, it can be used as an alignment film. Note that the present embodiment may be modified and implemented as follows.

In the above embodiment, the polarizing function film 3 is formed by uniaxially aligning the liquid crystalline polymer and the dichroic dye.
And 13 were formed, but need not necessarily be uniaxially oriented. That is, each pixel region may be divided into a plurality of domains, and a different alignment direction may be given to the liquid crystalline polymer and the dichroic dye for each of the divided domains.

In the above embodiment, the non-pixel region 13b
Has a wavelength of 10 μm and an energy density of 0.01 to 0.1 / c.
Although an infrared laser of m ² was irradiated, the wavelength and the energy density are not limited thereto. The point is that the non-pixel region may have heat energy higher than the glass-nematic liquid crystal transition temperature of the liquid crystalline polymer.

(Second Embodiment) Hereinafter, a second embodiment in which the liquid crystal display device according to the present invention is applied to a simple matrix type monochrome liquid crystal display device will be described, focusing on differences from the first embodiment. A description will be given based on FIG. In FIG. 3, the same members as those in FIG. 1 are denoted by the same reference numerals.

FIG. 3 is a sectional view of the liquid crystal display device of the present embodiment. As shown in FIG. 3, this liquid crystal display device has a transparent electrode 2 on a substrate 1 as in the first embodiment.
Are formed. On this transparent electrode 2, a polarizing function film 103 having a thickness of 500 ° is formed in contact with the liquid crystal layer 20. On the substrate 11 and the transparent electrode 12, a polarizing function film 113 having a thickness of 500 ° is formed. These polarizing function films 103 and 113 are basically the same as the film structure of the polarizing function film 13 illustrated in FIG.

In this embodiment, alignment films 104 and 114 made of polyimide are formed on the surfaces of the polarization function films 103 and 113 to a thickness of 500 °, respectively. The alignment films 104 and 114 have their surfaces subjected to an alignment treatment using a rubbing method.

Therefore, in the present embodiment, the point that the polarizing function films 103 and 113 have a polarizing function in the pixel region and a light blocking function in the non-pixel region is different from the polarizing function film 3 of the first embodiment. And 13, but not used for controlling the alignment of the liquid crystal. In the present embodiment, the polarizing function films 103 and 113 have
An anthraquinone black dye material is used as the dichroic dye.

Next, a method for forming the polarization functional films 103 and 113 will be described. In this embodiment, the non-pixel region has a wavelength of 360 nm and an energy density of ² J / cm ^2.
Is irradiated with ultraviolet laser. By irradiating the ultraviolet rays in this way, the main chain bond of the liquid crystalline polymer is blocked. Accordingly, the orientation of the liquid crystalline polymer is disordered, and accordingly, the orientation of the dichroic dye is also disordered. Therefore, the dichroic dye in the portion irradiated with the ultraviolet laser loses the order of the absorption axis and absorbs light in all directions, and thus has a light shielding property.

The polarizing function film 103 formed in the above embodiment
When the contrast of the liquid crystal display device of the present embodiment using Nos. 113 and 113 was measured, a value of “220” was obtained. This value is about 20% higher than that of a conventional liquid crystal display device using a black matrix.

According to the present embodiment described above, effects similar to the effects (1) and (2) of the first embodiment can be obtained, and the following effects can be obtained. (3) By separately providing the alignment film, the alignment can be controlled more suitably. It is considered that the contrast value of “220” is due to the improvement of the alignment performance.

The above embodiment may be modified as follows. In the above embodiment, the wavelength 360 is set in the non-pixel region.
Irradiation with an ultraviolet laser having an energy density of ² J / cm ² was performed, but not limited to this. In short, it is only necessary to supply the non-pixel region with energy capable of blocking the main chain bond of the liquid crystalline polymer.

In the above embodiment, the alignment film 104
And 114 are made of polyimide, but any alignment material such as polyamide or polyamideimide may be used. Also, the alignment treatment of the alignment films 104 and 114 is not limited to the rubbing method, and a photo alignment treatment or the like may be used.

In the above embodiment, the polarizing function film 1
Although the liquid crystal polymer and the dichroic dye are used as the materials 03 and 113, the liquid crystal polymer may not be used. In this case, the dichroic dyes may be arranged by using some conventional polarizing plate forming technique, and then energy may be applied to the non-pixel region to disturb the arrangement of the dichroic dyes in the same region.

Further, the locations of the polarizing function films 103 and 113 may be changed as appropriate. However, when the pair of substrates 1 and 11 are thick, it is preferable to provide them inside the pair of substrates 1 rather than outside them.

Other elements that can be changed in common to the above embodiments include the following. -Polarization functional films 3, 13, 10 used in the above embodiments.
The materials 3 and 113 are not limited to those described above. As the liquid crystalline polymer, for example, polyester,
A polyether type, a polystyrene type, or the like can be used. In addition, as the dichroic dye, naphthokin type,
2 over the entire visible wavelength range, such as triphenodioxazine
Those having color properties can be used. Further, the ratio between the liquid crystal polymer and the dichroic dye, the thickness thereof, and the like are also arbitrary.

In each of the above embodiments and its modifications, the glass-nematic liquid crystal transition temperature of the liquid crystalline polymer is set so that the non-pixel regions of the polarizing function films 3, 13, 103, and 113 have light shielding properties. Higher heat energy or energy capable of blocking the main chain bond of the liquid crystalline polymer was given as light energy, but is not limited thereto. The point is that the arrangement of the dichroic dyes in the non-pixel region may be disturbed by some means.

In each of the above embodiments, the polarization function film is provided on both of the opposing substrates. However, the polarization function film may be provided only on the substrate on the side from which light passing through the liquid crystal layer is emitted. Good.

In each of the above embodiments, the liquid crystal display device according to the present invention is applied to a simple matrix type monochrome liquid crystal display device. However, the present invention is applied to a color liquid crystal display device and an active matrix type liquid crystal display device. Such a liquid crystal display device can be similarly applied. Also, T
Instead of the N method, a method such as super twist nematic alignment, horizontal alignment, or bend alignment may be used.

In addition, the shapes and materials of the members used in the above embodiments are not limited to those described above.
For example, as each of the above substrates, a plastic substrate or a glass substrate other than polyethersulfone can be used. Also, an epoxy polymer resin or the like can be used as the sealing resin 30 or 30 ′, and a plastic or the like can be used as the spacer 31. Further, as the liquid crystal layer 20, cholesteric liquid crystal, ferroelectric liquid crystal, or the like can be used.

The following are the technical ideas that can be grasped from the above embodiment and its modifications. (1) A method for manufacturing a liquid crystal display device provided with a polarizing function film including a dichroic dye and a liquid crystalline polymer, wherein the film including the dichroic dye and the liquid crystalline polymer is uniaxially oriented. After the film is formed by heating, a portion to be a non-pixel region of the formed film is heated, and a light shielding function is imparted to the region by disturbing the orientation of the uniaxially oriented film. Of manufacturing a liquid crystal display device.

(2) A method of manufacturing a liquid crystal display device provided with a polarizing function film comprising a dichroic dye and a liquid crystalline polymer, wherein the film comprising the dichroic dye and the liquid crystalline polymer is uniaxial. After the film is oriented in the same direction, light energy is applied to each non-pixel region of the formed film to disturb the orientation of the liquid crystalline polymer, thereby providing a light blocking function to the region. A method for manufacturing a liquid crystal display device, comprising:

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a cross-sectional configuration of a first embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is a perspective view showing a structure and a forming procedure of the polarization functional film of the embodiment.

FIG. 3 is a sectional view showing a sectional configuration of a liquid crystal display device according to a second embodiment of the present invention.

[Explanation of symbols]

1, 11: plastic substrate, 2, 12: transparent electrode,
3, 13, 103, 113: polarization function film, 13a: pixel region, 13b: non-pixel region, 20: liquid crystal region, 30: seal resin, 31: spacer, 104, 114: alignment film.

Claims (3)

[Claims] 1. A liquid crystal display device comprising a polarizing function film provided with a light blocking function corresponding to each non-pixel region. 2. The liquid crystal display device according to claim 1, wherein the polarizing function film includes a dichroic dye, and the light blocking function is provided by selectively disturbing the arrangement of the dichroic dye. 3. The liquid crystal display device according to claim 2, wherein the polarizing function film further comprises a liquid crystalline polymer and is formed in contact with the liquid crystal layer.