JP3077960B2 - Manufacturing method of liquid crystal display device - Google Patents

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 liquid crystal display device in which a display medium is sandwiched between a pair of substrates arranged opposite to each other and picture elements are arranged in a matrix.

[0002]

2. Description of the Related Art Conventionally, there are liquid crystal display devices using various display modes. For example, as a liquid crystal display device utilizing an electro-optical effect, a twisted nematic (TN) mode using a nematic liquid crystal or a twisted nematic (TN) mode is used. A liquid crystal display device of a super twisted nematic (STN) mode has been put to practical use. Also, a liquid crystal display device using a ferroelectric liquid crystal (FLC) mode has been proposed. These conventional display mode liquid crystal display devices require a polarizing plate and thus have low light use efficiency, and require an alignment treatment, which complicates the manufacturing process.

[0003]

However, in the conventional liquid crystal display device of the display mode, there is a problem that the viewing angle characteristics are poor. For example, in the TN mode, when no voltage is applied, the initial alignment of liquid crystal molecules is 90
It has a structure in which the liquid crystal molecules are twisted and the major axis direction of the liquid crystal molecules rises at a certain angle (pretilt angle) on one substrate side. When a voltage is applied, alignment processing is performed so that liquid crystal molecules rise in the same direction. For this reason, when the liquid crystal molecules rise in the halftone, the liquid crystal molecules tilt in the same direction, so that the apparent refractive index differs depending on the direction in which the liquid crystal molecules are viewed. For this reason, the contrast greatly differs depending on the viewing direction. In an extreme case, a display abnormality such as an inversion phenomenon occurs.

Further, among such liquid crystal display devices, in an active matrix drive type liquid crystal display device, a plurality of pixel electrodes for applying a voltage to the liquid crystal are formed on one substrate, and each pixel electrode is selectively driven. A non-linear element such as a thin-film transistor is formed as the switching element to perform. Such a non-linear element has a large dependence on characteristics and deterioration of characteristics with respect to light irradiation. Therefore, usually, a resin light-shielding film is formed on the non-linear element to shield the non-linear element from light. Regarding such a resin light-shielding film on a TFT-LCD, see SID'92 DIGEST pp 789-782.
However, there is no description on the formation method. In general, since such a resin light-shielding film is formed by a spin coating method, there is a problem that material cost and equipment cost are high and throughput is low.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and is intended to manufacture a liquid crystal display device capable of improving viewing angle characteristics, reducing manufacturing costs, and improving throughput. The aim is to provide a method .

[0006]

According to the present invention, there is provided a liquid crystal display device comprising :
In the manufacturing method , a pair of substrates each having an electrode formed thereon are arranged facing each other with the electrodes inside, and a display medium is sandwiched between the pair of substrates and an electrode facing portion existing in a matrix is formed. Manufacture of liquid crystal display device as a picture element
In the method, between the pair of substrates, a photopolymerizable resin or
Is a material with at least black filler mixed in photosensitive resin
Injecting a mixture of a material and a liquid crystal compound, and the mixture
Is irradiated with light energy through a mask,
The liquid crystal phase and the polymer phase are phase-separated, and the liquid
Crystal molecules are arranged radially, concentrically or spirally.
Obtaining a display medium having at least one domain.
Therefore, the above object is achieved.

[0007]

[0008]

In one embodiment, at least one of the pair of substrates may be formed of a transparent substrate, and the electrodes formed on the transparent substrate may be formed of a material having a low ultraviolet transmittance. In one embodiment, at least one of the pair of substrates may be formed of a transparent substrate, and a color filter containing an ultraviolet absorbent may be formed on the transparent substrate.

[0010]

In the liquid crystal display device of the present invention, a display medium containing a polymer phase and a liquid crystal phase is held between a pair of insulating substrates each having at least one electrode formed thereon and transparent. . In the picture element portion, as shown in FIG. 6, the liquid crystal molecules form at least one domain arranged in a radial, concentric or spiral shape oriented in the wall direction of the polymer phase. FIG. 6A shows a case where the arrangement of liquid crystal molecules is radial,
(B) shows a concentric shape, and (c) shows a spiral shape. Such an arrangement of liquid crystal molecules can be obtained, for example, by forming spherulites in the alignment film.

When a voltage is applied to the above liquid crystal cell, the liquid crystal molecules rise radially, concentrically, or spirally. For this reason, the apparent refractive index from each direction becomes substantially the same, and there is a great effect in improving the viewing angle characteristics.

Further, a black filler is dispersed in the polymer phase, and the polymer phase containing the black filler functions as a light-shielding film.

In the method of the present invention, a mixture of a material in which a black filler is mixed in a monomer or oligomer of a photocurable resin or a photosensitive resin and a liquid crystal compound is injected into a gap between a pair of substrates. When the mixture is irradiated with light energy, the liquid crystal phase and the polymer phase undergo phase separation by photopolymerization. At this time, as described above, a domain in which the arrangement of the liquid crystal molecules is radial, concentric, or spiral is formed by the action of the alignment film having the spherulites. The mixture may contain a polymerization initiator such as a photoinitiator.

When the mixture is irradiated with light energy through a mask, a polymer phase is formed on the irradiated portion, and the other portion becomes a liquid crystal phase. Therefore, depending on the formation position of the mask, a polymer phase in which a black filler is dispersed can be formed over a thin film transistor element and used as a light-shielding film.

Since at least one of the pair of substrates is transparent, a mask may be set on the back surface of the substrate. However, when a color filter formed on one of the transparent substrates is formed from a material containing an ultraviolet absorbent, this mask is formed. When irradiating light energy from the substrate side, this can be used as a mask. Therefore, phase separation can be performed by self-alignment, and a liquid crystal display device with high alignment accuracy can be obtained. In addition, when an electrode formed on one substrate is formed from a material having a low ultraviolet transmittance, the electrode can be used as a mask and can prevent color fading of a color filter which is a problem during exposure.

It is conceivable that a black filler remains in the liquid crystal portion on the picture element electrode. However, this black filler is uniformly dispersed in the photosensitive resin, and the black filler has an increased adhesion to the photosensitive resin. It does not elute into the liquid crystal as an impurity and has a high resistance, so there is no problem in displaying.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 is a sectional view showing a liquid crystal display device of Embodiment 1. In this liquid crystal display device, a pair of substrates 1 and 10 made of a glass plate or the like are arranged to face each other, and a display medium having a polymer phase 15 and a liquid crystal phase 16 is provided in the gap. A pixel electrode 9 is formed on the display medium side surface of one (lower) substrate 1, and a counter electrode 12 is formed on the display medium side surface of the other substrate 10.
A portion facing 2 is a picture element portion. A polymer phase 15 is mainly formed in a region other than the picture element portion including the TFT 13 formation region, and a black filler is dispersed in the polymer phase 15. The picture element mainly includes a liquid crystal phase 16.
For example, as shown in FIG. 6A, domains in which liquid crystal molecules are arranged radially or concentrically or spirally in the direction of the wall of the polymer phase 15 are formed.

This liquid crystal display device is manufactured as follows.

First, the steps of manufacturing the TFT forming substrate will be described. On a substrate 1 having an insulating surface, p-Si
A semiconductor film such as a film is formed by low pressure chemical vapor deposition (LPCVD) or the like with a thickness of 25 to 200 nm, preferably 70 to 100 nm.
The semiconductor layer 2 is formed by depositing and patterning to a thickness of about nm.

Next, an SiO ₂ film is formed on the semiconductor layer 2 by PC.
200 to 500 nm, preferably 200 to 500 nm by a VD method or the like.
The gate insulating film 3 is formed by depositing and patterning to a thickness of about nm. A gate electrode 4 is formed thereon by depositing a metal film to a thickness of about 200 to 400 nm by a sputtering method or the like.

Next, from the gate electrode 4 to the channel region, a V group element such as phosphorus or a compound thereof or an I group such as boron.
Acceleration voltage of 50 to 50
The contact layer 5 is formed by ion implantation at about 100 keV.

Next, a SiN _x or SiO ₂ film or the like is deposited thereon to a thickness of about 300 to 500 nm by a plasma CVD method or the like, and a predetermined hole is etched to open a contact hole. To form

Next, a source electrode 7 and a drain electrode 8 are formed thereon by depositing a conductive film to a thickness of about 200 to 700 nm by a sputtering method or the like. Further, a transparent conductive film such as an indium tin oxide film (ITO) is deposited to a thickness of about 50 to 100 nm by a sputtering method or the like to form the picture element electrode 9, thereby completing the TFT 13.

Next, a process for manufacturing the opposing substrate will be described. First, a pigment dispersion type color filter 11 is formed on a substrate 10 having an insulating surface by a printing method, an electrodeposition method, a spin coater or the like, and is patterned into a predetermined shape. A transparent conductive film such as ITO is deposited thereon by sputtering or the like to a thickness of about 50 to 100 nm to form the counter electrode 12.

The pixel electrode 9 on the TFT-formed substrate obtained as described above and the color filter 1 on the opposing substrate are obtained.
1 and an alignment film (not shown) is formed. To this alignment film, for example, nylon 6.6 is applied as an alignment film, baked to remove the solvent, and then removed to form a spherulite. Thereafter, 4.5 μm plastic beads are sprinkled on the opposing substrate, and both substrates are bonded to each other using a sealing resin to produce a liquid crystal cell as shown in FIG. 2A.

Next, a process for forming a display medium will be described. First, a mixture of a liquid crystal compound and a material in which at least a black filler is mixed in a photopolymerizable resin or a photosensitive resin is injected into a gap between the pair of substrates, and the mixture is irradiated with light energy through a mask. As a result, the photopolymerizable resin or the photosensitive resin undergoes photopolymerization, the polymer compound obtained by the polymerization and the liquid crystal compound undergo phase separation, and the polymer phase 15 is formed in the light-irradiated portion, and the liquid crystal is formed in the non-irradiated portion. Phase 16
Is formed. At this time, since a spherulite is formed in the alignment film, one domain in which liquid crystal molecules in the liquid crystal phase are radial is formed in the liquid crystal phase 16 based on the spherulite.

The photocurable resin includes R-684
(Nihon Kayaku), styrene, isobornyl methacrylate, and other monomers or oligomers can be used. As the photosensitive resin, a negative type or a positive type can be used.

As the black filler, carbon black, pigments such as titanium black, aniline black, iron oxide, manganese oxide and bismuth sulfide can be used.

As the above-mentioned liquid crystal compound, any material can be used as long as it shows a liquid crystal state at around normal temperature, and it can be used in conventional TN mode, STN mode, ECB mode, ferroelectric liquid crystal display mode, light scattering mode and the like. Any of the liquid crystal materials used can be used. For example, ZLI-479 containing 0.4% by weight of a chiral agent (S-811)
2 (manufactured by Merck).

The mixture may contain a photoinitiator in addition to a photocurable resin or a photosensitive resin in which a black filler is dispersed in advance, and a liquid crystal material. As a photoinitiator,
For example, Irgacure 651 (made by Ciba Geigy) or the like can be used.

As the mask, a color filter 11 and a counter electrode 12 formed on the counter substrate side can be used.

In this example, a display medium was formed as follows.

First, as shown in FIG. 2B, carbon black or pigment was added to 0.1 g of R-684 (manufactured by Nippon Kayaku) as a photocurable resin between the substrates bonded as described above. 35-45wt black filler
% Of styrene and 0.85 g of isobornyl methacrylate as a liquid crystal material containing 0.4% by weight of a chiral agent (S-811).
4792 (manufactured by Merck) and Irgacure 651 (manufactured by Ciba-Geigy) 0.002 as a photoinitiator.
A mixture 14 containing 5 g is injected in a transparent state (about 35 ° C.).

Next, a mask 17 having a light shielding property is set on the counter substrate side so that light does not hit the pixel electrodes 9 on the TFT forming side substrate. Thereafter, while maintaining the same temperature, an irradiation intensity of 1 was obtained by using a high-pressure mercury lamp capable of obtaining parallel rays.
Irradiation for 1 second from the counter substrate side at the position of 0 mW / cm ² -3
A cycle of no irradiation for 0 seconds is repeated 20 times, and then irradiation is performed for 10 minutes. This causes the photocurable resin to be photopolymerized,
As shown in FIG. 2C, the polymer is phase-separated into a polymer phase 15 in which a black filler is dispersed and a liquid crystal phase 16.

Observation of the obtained panel with a polarizing microscope revealed that the liquid crystal domain 16 having the same regularity as the dot pattern of the picture element electrode 9 (the same regularity as the picture element) and the TFT 1
The polymer phase 15 (light-shielding layer) having a line pattern including the upper part 3 was confirmed. In the liquid crystal domain 16, the arrangement of the liquid crystal molecules was radial.

Example 2 In this example, a display medium was manufactured using a negative photosensitive resin as the photocurable resin.

Both substrates were prepared in the same procedure as in Example 1,
As shown in FIG. 3A, bonding is performed, and as shown in FIG. 3B, an OMR as a negative photosensitive resin is
-83 (manufactured by Tokyo Ohka Co., Ltd.) in which 35-45 wt% of a black filler composed of carbon black or pigment is dispersed in 0.1 g, 0.05 g of styrene and 0.85 g of isobornyl methacrylate are used as a liquid crystal material. ZLI-47 containing 0.4% by weight of a chiral agent (S-811)
92 (manufactured by Merck) and Ir as a photoinitiator
gacure651 (manufactured by Ciba-Geigy) 0.0025 g
Is injected in a transparent state (about 35 ° C.).

Next, a mask 27 having a light-shielding property so that light does not hit the pixel electrodes 9 on the TFT forming substrate is set on the counter substrate side. Thereafter, while maintaining the same temperature, an irradiation intensity of 1 was obtained by using a high-pressure mercury lamp capable of obtaining parallel rays.
Irradiation for 1 second from the counter substrate side at the position of 0 mW / cm ² -3
A cycle of no irradiation for 0 seconds is repeated 20 times, and then irradiation is performed for 10 minutes. This causes the photocurable resin to be photopolymerized,
As shown in FIG. 3C, the liquid crystal phase 26 and the polymer phase 25 in which the black filler is dispersed are phase-separated.

When the obtained panel was observed with a polarizing microscope, the liquid crystal domain 26 having the same regularity (the same regularity as the picture element) as the dot pattern of the picture element electrode 9 and the TFT 1 were obtained.
The polymer phase 25 (light-shielding layer) having a line pattern including the top 3 was confirmed. In the liquid crystal domain 26, the arrangement of the liquid crystal molecules was radially oriented toward the wall of the polymer phase 25.

Example 3 In this example, instead of forming a mask on the counter substrate side, an ultraviolet absorber was mixed into a color filter on the counter substrate, and ultraviolet irradiation was performed using this as a mask.

A substrate on which a TFT is formed and a substrate on the opposite side are manufactured in the same procedure as in Example 1 except that an ultraviolet absorber is mixed into the color filter 31 on the opposite substrate.

The above-mentioned alignment film (not shown) is formed on the pixel electrodes 9 on the obtained TFT forming substrate and on the color filters on the opposing substrate. After that, 4.
5 μm plastic beads are sprinkled, and both substrates are bonded together using a sealing resin to produce a liquid crystal cell as shown in FIG.

Next, as shown in FIG. 4B, R-684 (manufactured by Nippon Kayaku Co., Ltd.)
35 g / g of a black filler made of carbon black or pigment dispersed in 1 g, 0.05 g of styrene and 0.85 g of isobornyl methacrylate, and 0 chiral agent (S-811) as a liquid crystal material. .4
4 g of ZLI-4792 (manufactured by Merck) containing weight%
And a mixture 34 obtained by mixing 0.0025 g of Irgacure 651 (manufactured by Ciba Geigy) as a photoinitiator is injected in a transparent state (about 35 ° C.).

Then, while maintaining the same temperature, the irradiation intensity was 10 mW using a high-pressure mercury lamp capable of obtaining parallel rays.
At the position of / cm ² , a cycle of irradiation for 1 second to 30 seconds without irradiation is repeated 20 times from the counter substrate side, and then irradiation is performed for 10 minutes. At this time, the color filter 31 in which the ultraviolet absorber is mixed functions as a mask, and the photocurable resin is photopolymerized, and as shown in FIG. The phase is separated into the liquid crystal phase 36.

When the obtained panel was observed with a polarizing microscope, the liquid crystal domain 36 having the same regularity (the same regularity as the picture element) as the dot pattern of the picture element electrode 9 and the TFT 1 were obtained.
A polymer pattern 35 (light-shielding layer) having a line pattern including the upper part No. 3 was confirmed. In the liquid crystal domain 36, the arrangement of the liquid crystal molecules was radially oriented toward the wall of the polymer phase 35.

(Embodiment 4) In this embodiment, instead of forming a mask on the counter substrate side, a counter electrode 42 is formed using a material having a low ultraviolet transmittance, such as ZnO, and ultraviolet irradiation is performed using this as a mask. went.

A pigment-dispersed color filter 41 is formed on a TFT forming substrate formed in the same procedure as in Example 1 by a printing method, an electrodeposition method, a spin coater, or the like, and is patterned into a predetermined shape.

Next, an opposite substrate is manufactured in the same procedure as in Example 1 except that zinc oxide (ZnO) is used instead of ITO as the transparent conductive film. The ultraviolet transmittance of the counter electrode 42 can be set to 5% or less.

The above-mentioned alignment film (not shown) is formed on the pixel electrodes 9 of the obtained TFT forming substrate and on the counter electrode 42 of the counter substrate.

Thereafter, plastic beads of 4.5 μm are scattered on the opposing substrate, and both substrates are bonded to each other using a sealing resin to produce a liquid crystal cell as shown in FIG.

Next, as shown in FIG. 5B, R-684 (manufactured by Nippon Kayaku Co., Ltd.)
35 g / g of a black filler made of carbon black or pigment dispersed in 1 g, 0.05 g of styrene and 0.85 g of isobornyl methacrylate, and 0 chiral agent (S-811) as a liquid crystal material. .4
4 g of ZLI-4792 (manufactured by Merck) containing weight%
And a mixture 44 obtained by mixing 0.0025 g of Irgacure 651 (manufactured by Ciba Geigy) as a photoinitiator is injected in a transparent state (about 35 ° C.).

Thereafter, while maintaining the same temperature, using a high-pressure mercury lamp capable of obtaining parallel rays, the irradiation intensity was 10 mW.
At the position of / cm ² , a cycle of irradiation for 1 second to 30 seconds without irradiation is repeated 20 times from the counter substrate side, and then irradiation is performed for 10 minutes. At this time, the counter electrode 42 having an ultraviolet transmittance as low as 5% or less functions as a mask, the photocurable resin is photopolymerized, and as shown in FIG. 45 and a liquid crystal phase 46.

Observation of the obtained panel with a polarizing microscope revealed that the liquid crystal domain 46 having the same regularity as the dot pattern of the picture element electrode 9 (the same regularity as the picture element) and the TFT 1
The polymer phase 45 (light-shielding layer) having a line pattern including the upper part No. 3 was confirmed. Further, in the liquid crystal domain 46, the arrangement of the liquid crystal molecules was radially oriented toward the wall of the polymer phase 45.

Although the embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications can be made.

In the above embodiment, the arrangement of liquid crystal molecules is made radial by forming spherulites on the alignment film. However, the present invention is not limited to this. May be concentric or spiral. Instead of forming spherulites on the alignment film, any other method that can arrange the liquid crystal molecules radially, concentrically, or spirally by another method can be adopted. For example, a method of forming concavities and convexities on the alignment film in the same arrangement as that of the liquid crystal molecules described above, or a method of forming a mountain-like projection at a position corresponding to the center of a pixel portion of the alignment film can be adopted. In addition, it is a matter of course that a method can be adopted in which a similar material is formed on the base film of the alignment film and its shape is transmitted to the alignment film, and as a result, a desired shape is formed in the alignment film.

Further, in the above embodiment, one domain is formed in the picture element portion. However, the present invention is not limited to this, and the arrangement of liquid crystal molecules may be radial, concentric or spiral in each picture element portion. Needless to say, a configuration having two or more domains in a shape may be employed.

In the above embodiment, a liquid crystal display device in which display is performed by active matrix driving using a TFT has been described. However, the present invention is not limited to this.
The present invention can also be applied to a liquid crystal display device that performs display by active matrix driving using (Metal Insulator Metal) or the like, or a liquid crystal display device driven by simple matrix driving.

As a liquid crystal material, a conventional TN mode, S
TN mode, ECB mode, ferroelectric liquid crystal display mode,
Any of liquid crystal materials used for a liquid crystal display device such as a light scattering mode can be used, and a structure in which a polarizing plate is formed is also possible. Further, the present invention can be applied to both a transmission type liquid crystal display device and a reflection type liquid crystal display device.

As the substrate material, any substrate can be used as long as at least one of the pair is transparent and has an insulating surface. In addition to a glass substrate, a plastic film substrate or the like may be used. An insulating film may be formed thereon.

[0061]

As is apparent from the above description, in the present invention, the liquid crystal molecules are arranged radially, concentrically or spirally in the picture element portion, which has been a problem in the conventional liquid crystal display device. A display abnormality such as a change in contrast or an inversion phenomenon depending on the viewing angle direction does not occur, and the viewing angle characteristics can be improved. Since there is no need to provide a polarizing plate, the light use efficiency can be increased, and there is no need to perform alignment treatment of the alignment film, so that the manufacturing process can be simplified.

Since the polymer phase in which the black filler is dispersed and the liquid crystal phase are separated, the cost of forming the light-shielding film can be reduced and the throughput can be improved. Also,
By irradiating light energy through the mask, a liquid crystal domain can be formed on the picture element electrode and a light-shielding film can be formed on the TFT.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a liquid crystal display device according to a first embodiment.

FIG. 2 is a sectional view illustrating a manufacturing process of the liquid crystal display device of Example 1.

FIG. 3 is a cross-sectional view illustrating a manufacturing process of the liquid crystal display device of Example 2.

FIG. 4 is a cross-sectional view illustrating a manufacturing process of the liquid crystal display device of Example 3.

FIG. 5 is a sectional view illustrating a manufacturing process of the liquid crystal display device of Example 4.

FIG. 6 is a view showing an arrangement state of liquid crystal molecules in a picture element portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 10 Insulating substrate 2 Semiconductor layer 3 Gate insulating film 4 Gate electrode 5 Contact layer 6 Interlayer insulating film 7 Source electrode 8 Drain electrode 9 Pixel electrode 11, 31, 41 Color filter 12, 42 Counter electrode 13 TFT element 14, 24, 34, 44 Mixture 15, 25, 35, 45 Polymer phase 16, 26, 36, 46 Liquid crystal phase 17, 27 Mask

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-131231 (JP, A) JP-A-5-107527 (JP, A) JP-A-51-20854 (JP, A) JP-A-4- 251220 (JP, A) Special Table Hei 5-504210 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/1334 G02F 1/1343 G02F 1/1362 G02F 1/13 101 G09F 9/30

Claims (1)

(57) [Claims] 1. A pair of substrates each having electrodes formed thereon are opposed to each other with the electrodes inside, and a display medium is sandwiched between the pair of substrates and an electrode facing portion exists in a matrix. In the method of manufacturing a liquid crystal display device having a pixel portion, a mixture of a liquid crystal compound and a material obtained by mixing at least a black filler in a photopolymerizable resin or a photosensitive resin is injected between the pair of substrates. Irradiating the mixture with light energy through a mask to separate the liquid crystal phase and the polymer phase by photopolymerization, and the liquid crystal molecules are arranged radially, concentrically or spirally in the picture element portion. Obtaining a display medium having at least one domain as described above.