JP2002107733A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily extend the viewing angle of a liquid crystal display device. SOLUTION: With respect to a liquid crystal display 1 where a liquid crystal 6 is held between a driving substrate 2 and a counter substrate 3, an alignment film 4 reacting on ultraviolet ray irradiation is provided on the liquid crystal side of the driving substrate 2 or the counter substrate 3, and a high polymer wide viewing angle film 10 and polarizing plates 8 and 9 are laminated on the outside of the driving substrate 2 or the counter substrate 2 of a liquid crystal cell provided with this alignment film 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device in which the viewing angle is expanded in all directions by laminating a polymer type wide viewing angle film on a liquid crystal cell using an ultraviolet-sensitive liquid crystal alignment film as an alignment film. .

[0002]

2. Description of the Related Art In general, a liquid crystal display element has a disadvantage that, when viewed obliquely, a phase difference occurs between ordinary light and extraordinary light due to a birefringence effect peculiar to the liquid crystal, and this causes interference, resulting in a narrow viewing angle. Having. In order to improve the viewing angle characteristics, various techniques for widening the viewing angle have been proposed in recent years. For example, (i) a split orientation method based on a conventional rubbing method, (ii) IPS (In Plane Switching). ) Method: T
A method in which a comb-shaped electrode is provided on an FT substrate and a horizontally aligned liquid crystal is driven only by the TFT substrate. (Iii) MVA (Multi-domain Ver.
(Critical Alignment) method: There is a method in which a projection is provided in a pixel and the alignment direction of vertically aligned liquid crystal is divided at the boundary to widen the viewing angle.

As a method of simply increasing the viewing angle, there is a method of laminating a discotic type viewing angle expansion film on a liquid crystal display panel on which an alignment film is formed by a conventional rubbing method.

[0004]

Among the techniques for widening the viewing angle proposed so far, the split orientation method requires complicated process processing using photolithography, and also requires a photolithographic process. Since the surface of the alignment film is easily contaminated with the resist residue after the resist is peeled off, it is difficult to ensure the reliability, and it has not yet been put to practical use.

[0005] The IPS system is difficult to be applied to AV equipment and applied to small portable information terminals due to a decrease in aperture ratio, an increase in drive voltage, and a decrease in response speed.

The method of forming ribs on a substrate typified by MVA includes a decrease in transmittance and contrast, a decrease in liquid crystal injection speed, an uneven display due to a gap material being loaded on ribs, a decrease in response speed, image sticking, and material reliability. There are problems such as.

In the IPS system and the MVA system, a conventional TN-type liquid crystal display panel manufacturing line for performing a rubbing process cannot be used as it is, and it is necessary to change a design, a process, a liquid crystal material, and the like.

The method of using a discotic type viewing angle widening film has been commercialized widely, but has the drawback that black-and-white reversal, black reversal and blackout are remarkable depending on the angle, and the viewing angle widening performance is not sufficient. is there.

Therefore, an object of the present invention is to easily obtain a liquid crystal display device having a wide viewing angle.

[0010]

SUMMARY OF THE INVENTION The present inventor has proposed that an ultraviolet-sensitive alignment film is provided in place of an alignment film formed by a rubbing method, and a specific viewing angle widening film is laminated on a liquid crystal cell. It has been found that the viewing angle in the direction can be expanded.

That is, the present invention relates to a liquid crystal display device having a liquid crystal sandwiched between a driving substrate and a counter substrate with an alignment film interposed therebetween. Provided is a liquid crystal display device provided with a film, in which a polymer-type wide viewing angle film and a polarizing plate are sequentially laminated on the outside of a driving substrate or a counter substrate of a liquid crystal cell provided with an ultraviolet reactive type alignment film.

The present invention also relates to a method for manufacturing a liquid crystal display device comprising a liquid crystal sandwiched between a driving substrate and a counter substrate with an alignment film interposed therebetween. Forming a UV-type alignment film by irradiating polarized UV light with a polymer-type alignment film material, and a polymer-type wide field of view outside the drive substrate or counter substrate of a liquid crystal cell equipped with the UV-ray alignment film A method for manufacturing a liquid crystal display element, comprising: laminating a corner film.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. In each drawing, the same reference numerals represent the same or equivalent components.

FIG. 1 is an example of a schematic cross-sectional view of a transmission type liquid crystal display element 1 according to one embodiment of the present invention.

The liquid crystal display element 1 has a driving substrate of T
This is an active matrix type liquid crystal display device having an FT substrate 2. A TN liquid crystal 6 is sandwiched between the TFT substrate 2 and the opposing substrate 3 via the alignment films 4 and 5 to form a TN liquid crystal cell 7. The TF of the TN type liquid crystal cell 7
Polarizing plates 8 and 9 are provided outside the T substrate 2 and outside the opposing substrate 3, respectively. Here, the combination itself of the TN type liquid crystal cell 7 and the polarizing plates 8 and 9 can be the same as a known TN type liquid crystal display element.

The TFT substrate has a diagonal of 1.11.
8cm (0.44 inch) or more, high temperature Poly-Si TFT substrate with 113,000 pixels or more, diagonal 6.35c
It is possible to use a low-temperature Poly-Si TFT substrate having m (2.5 inches) or more and 180,000 dots or more pixels.

On the other hand, the liquid crystal display element 1 uses an ultraviolet-sensitive alignment film as the alignment film 4 on the TFT substrate side and the alignment film 5 on the counter substrate side, and uses the TFT substrate 2 and the polarizing plate 8 as an alignment film.
And a polymer-type wide-viewing-angle film 10 is provided between the opposite substrate 3 and the polarizing plate 9.

By providing an ultraviolet-reactive alignment film as the alignment films 4 and 5, the regulating force of the liquid crystal molecules at the substrate interface can be controlled more flexibly than when an alignment film is provided by a rubbing method. The birefringence of the fixed layer of the liquid crystal molecules at the interface can be reduced, thereby making it possible to widen the viewing angle in the left-right direction.

For the formation of the UV-reactive alignment film, a photocrosslinkable polyimide-based material or a photocrosslinkable polyvinyl cinnamate-based material (Japanese Patent Laid-Open No. 7-104302) can be used. UV-sensitive alignment film material composed of polymer (USP 5,958,292, US
P. 5,846, 431, see IDW'99).

As a method for forming an ultraviolet-reactive alignment film using an ultraviolet-reactive alignment film material composed of a polyimide-type benzophenone-based polymer, a coating film of the ultraviolet-reactive alignment film material having a thickness of 15 mm is formed on a substrate. It is preferable to form a film having a thickness of about 80 nm and irradiate polarized ultraviolet rays having a wavelength of 300 to 400 nm. In this case, the method of irradiating polarized ultraviolet light is shown in FIG.
As shown in FIG. 2, first irradiation (FIG. 4A) for irradiating the substrates 2 and 3 with P-polarized light, and thereafter, the substrates 2 and 3 are rotated 90 °.
The irradiation is performed in two stages of the second irradiation (FIG. 3B) in which the light is rotated to irradiate the P-polarized light, or as shown in FIG. 3, the irradiation is performed in one stage using the combined light of the P-polarized light and the S-polarized light. .

When the irradiation of polarized ultraviolet light is performed in two stages, the energy ratio between the first irradiation and the second irradiation is preferably set to 2: 1 to 8: 1, and the integrated irradiation of each of the first irradiation and the second irradiation is performed. Preferably, the energy is 0.05 J / cm ^{2 to} 60 J / cm ² . In addition, the irradiation angle θ is 0 to 1st irradiation.
It is preferable to set the second irradiation at 45 ° and the second irradiation at 20 to 45 °.

On the other hand, when the irradiation of polarized ultraviolet light is performed in only one step, the polarization ratio of P-polarized light to S-polarized light is 1: 2 to 1:
It is preferably 30.

On the other hand, in the present invention, the polymer type wide viewing angle film 10 is provided to enlarge the vertical viewing angle of the liquid crystal display device.

As the polymer type wide viewing angle film 10,
As shown in FIG. 4, an adhesive 11 adhered to the liquid crystal cell 7
And a support film (TA) provided on the polarizing plates 8 and 9 side.
C) a polymer liquid crystal 13 is sandwiched between the liquid crystal cell 12 and the liquid crystal cell 13 lying on the liquid crystal cell 7 side and standing on the polarizing plates 8 and 9 side; A hybrid nematic structure in which the deformation structure on the ninth side is assumed to be a linear deformation can be preferably used. Further, as the polymer type wide viewing angle film 10, the layer thickness of the polymer liquid crystal 13 is 0.5 to 0.8 μm, the average tilt angle is 25 ° to 45 °, and the birefringence is 0.15 to 0.35.
(Λ590 nm) is preferred.

As a method for installing the polymer type wide viewing angle film 10 with respect to the liquid crystal cell 7, for the polymer type wide viewing angle film 10 provided outside the TFT substrate 2, the orientation axis direction of the polymer liquid crystal 13 is set to the TFT. With respect to the polymer type wide viewing angle film 10 provided so as to be perpendicular to the orientation direction of the liquid crystal of the substrate 2 and on the outside of the counter substrate 3, the orientation axis direction of the polymer liquid crystal 13 is adjusted to the direction of the liquid crystal of the counter substrate 3. It should be perpendicular to the orientation direction. More specifically, the polarizing plate 8
, The orientation axis of the polymer liquid crystal 13 of the polymer wide viewing angle film 10, the orientation of the liquid crystal of the TFT substrate 2, the orientation of the liquid crystal of the counter substrate 3, the height of the polymer wide viewing angle film 10. The orientation axis direction of the molecular liquid crystal 13 and the absorption axis of the polarizing plate 9 are arranged in the directions shown in FIG. 5 or FIG.

The present invention has been described above with reference to the liquid crystal display element 1 shown in FIG. 1. In the present invention, an ultraviolet-sensitive alignment film is used as an alignment film, and a polymer-type wide field of view is provided outside a driving substrate or a counter substrate. Various modes can be adopted as long as the corner film is provided. For example, in the present invention, the driving substrate is T
It is not limited to the FT substrate.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments.

Example 1 A diagonal of 8.89 cm (3.5 inches), the number of display dots is 20
Over 10,000 low-temperature Poly-Si TFT substrates and a counter substrate on which color filters are formed, a UV-sensitive alignment film material (product name) made of polyimide-type benzophenone polymer
Opto Align Materials, manufactured by ELSICON Co.)
After preliminarily drying at 190 ° C for 30 minutes,
Each substrate was irradiated with polarized ultraviolet light.

In this case, as the irradiation of polarized ultraviolet light, the first irradiation of irradiating P-polarized ultraviolet light from a position at an elevation angle of 70 ° to align the liquid crystal molecules, and the substrate is rotated by 90 ° to develop a pretilt angle. P from the position of elevation 70 °
Two-stage irradiation of polarized UV was performed (FIG. 2).

As the ultraviolet lamp, a commercially available electrodeless discharge lamp "H" Bulb manufactured by Fusion Co., Ltd. is used.
Light of m or less was cut by a glass plate. Also,
A polarizer having a dielectric multilayer film deposited thereon was disposed in front of an ultraviolet lamp, and the degree of polarization was about 10: 1.

The integrated amount of irradiation of the polarized ultraviolet light on each substrate was 16.7 J / cm ² for the first irradiation and 3.3 J / cm ² for the second irradiation.
cm ² , the integrated light amount was 20 J / cm ^2, and the energy ratio between the first irradiation and the second irradiation was 5: 1. At this time, U
As a result of the measurement, the emission intensity of the V light (light source) was 100 ± 10
mW / cm ² .

After irradiating polarized ultraviolet light, both substrates were adhered to each other with a cell gap of 3.5 μm by a known method, and a liquid crystal was sealed to produce a liquid crystal display cell.

A commercially available polymer-type wide viewing angle film (NH film (Nematic Hybrid Film) manufactured by Nippon Petrochemical Co., Ltd.) and a polarizing plate are provided on the TFT substrate side and the counter substrate of the liquid crystal display cell, respectively. Was laminated. At this time, as the polymer type wide viewing angle film, a polymer liquid crystal layer having a thickness of 0.65 μm, an average tilt angle of 37 °, and a birefringence of 0.234 was used.

When the viewing angle characteristics of the obtained liquid crystal display device were measured, the isocontrast curve shown in FIG.
FIG. 7 (b) shows an inverted area diagram. A good moving image having no inverted area at 70 ° vertically and 85 ° horizontally and having a contrast ratio of 10: 1 or more was obtained.

Example 2 Example 1 was repeated except that the arrangement conditions of the liquid crystal display cell, the polymer type wide viewing angle film, and the polarizing plate were as shown in FIG. 6, and the viewing angle characteristics were measured. As a result, an equi-contrast curve shown in FIG. 8A and an inversion area diagram shown in FIG. 8B are obtained. There is no inversion area at 65 ° vertically and 85 ° left and right, and the contrast ratio is 10: 1 or more. Good moving images were obtained.

Example 3 The irradiation of the ultraviolet-sensitive alignment film material with polarized ultraviolet light was performed in one step using a synthetic ultraviolet light of P-polarized light and S-polarized light at an elevation angle of 45 ° and an irradiation light amount of 20 J / cm ² as shown in FIG. Example 1 was repeated except that irradiation was performed only, and the viewing angle characteristics were measured.
As a result, the same viewing angle characteristics as in Example 1 were obtained.

Comparative Example 1 A commercially available alignment film for rubbing was formed on the TFT substrate and the color filter in place of the UV-reactive alignment film material, and rubbing treatment was performed. Example 1 was repeated except that the arrangement conditions of the cell, the polymer type wide viewing angle film, and the polarizing plate were as shown in FIG. 6, and the viewing angle characteristics were measured. As a result, an isocontrast curve shown in FIG. 9A and an inversion area diagram shown in FIG. 9B were obtained, and the area without inversion was only 60 ° vertically and 35 ° horizontally.

Comparative Example 2 Comparative Example 1 was repeated except that a discotic liquid crystal type film (WV film manufactured by Fuji Photo Film) was used instead of the polymer type wide viewing angle film (NH film manufactured by Nippon Petrochemical Co.). The angular properties were measured. As a result, FIG.
0 (a) and an inversion area diagram shown in FIG. 10 (b) are obtained.
° and left and right were only 60 °.

[0039]

According to the present invention, since the alignment film is formed using an ultraviolet-reactive alignment film, the regulation force of the liquid crystal molecules at the substrate interface can be controlled more flexibly as compared with the rubbing method, and the liquid crystal molecules at the substrate interface can be controlled. The birefringence of the fixed layer is alleviated, and the viewing angle in the left-right direction can be increased. Furthermore, since the polymer type wide viewing angle film is laminated, the vertical viewing angle can be corrected. Therefore, the vertical and horizontal viewing angles are corrected, and a wide viewing angle panel with a small inversion area in all directions can be realized. Further, the liquid crystal display element of the present invention can be easily manufactured because a conventional TN type liquid crystal display panel manufacturing line for performing a rubbing treatment can be used as it is.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a liquid crystal display device of the present invention.

FIG. 2 is an explanatory diagram of irradiation conditions of polarized ultraviolet rays on a substrate coated with an ultraviolet alignment film material.

FIG. 3 is an explanatory view of irradiation conditions of polarized ultraviolet rays on a substrate coated with an ultraviolet alignment film material.

FIG. 4 is a structural diagram of a polymer type wide viewing angle film.

FIG. 5 is a layout diagram of a liquid crystal cell and a polymer type wide viewing angle film.

FIG. 6 is a layout diagram of a liquid crystal cell and a polymer type wide viewing angle film.

FIG. 7 is a view angle characteristic diagram showing an equal contrast curve and an inversion region of the liquid crystal display cell of Example 1.

FIG. 8 is a view angle characteristic diagram showing an equal contrast curve and an inversion region of the liquid crystal display cell of Example 2.

9 is a view angle characteristic diagram showing an equal contrast curve and an inversion region of the liquid crystal display cell of Comparative Example 1. FIG.

FIG. 10 is a view angle characteristic diagram showing an equal contrast curve and an inversion region of the liquid crystal display cell of Comparative Example 2.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display element, 2 ... TFT substrate, 3 ... Counter substrate, 4 ... Alignment film, 5 ... Alignment film, 6 ... TN liquid crystal,
7: liquid crystal cell, 8: polarizing plate, 9: polarizing plate, 10: polymer type wide viewing angle film, 13: polymer liquid crystal

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H049 BA02 BA06 BA42 BB03 BB62 BC22 2H090 HB08Y HB13Y KA05 LA04 MA06 MB14 2H091 FA08X FA08Z FA11X FA11Z FB02 FD09 FD10 GA13 HA07 LA17 LA19

Claims (6)

[Claims] 1. A liquid crystal display device comprising a liquid crystal sandwiched between a driving substrate and a counter substrate via an alignment film, wherein an ultraviolet reactive alignment film is provided as an alignment film on the driving substrate or the counter substrate. And a liquid crystal display device in which a polymer type wide viewing angle film and a polarizing plate are sequentially laminated on the outside of a driving substrate or a counter substrate of a liquid crystal cell provided with an ultraviolet-sensitive alignment film. 2. The liquid crystal display device according to claim 1, wherein the ultraviolet-sensitive alignment film is made of a photo-crosslinkable polyimide material. 3. The liquid crystal display device according to claim 1, wherein the polymer type wide viewing angle film comprises a polymer liquid crystal having a hybrid nematic structure. 4. A method for manufacturing a liquid crystal display device comprising a liquid crystal sandwiched between a driving substrate and a counter substrate with an alignment film interposed therebetween, wherein at least one of the driving substrate and the counter substrate is provided with an ultraviolet-sensitive alignment film material. Forming a UV-sensitive alignment film by irradiating polarized UV light, laminating a polymer-type wide viewing angle film on the outside of the driving substrate or counter substrate of a liquid crystal cell equipped with the UV-sensitive alignment film A method for manufacturing a liquid crystal display element, comprising: 5. The method according to claim 4, wherein a photo-crosslinkable polyimide-based material is used as the UV-reactive alignment film material. 6. The method for producing a liquid crystal display device according to claim 4, wherein a film composed of a polymer liquid crystal having a hybrid nematic structure is used as the polymer type wide viewing angle film.