JP2003215576A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device with improved adhesion properties of a group of arrays of protrusions and a light reflection layer to each other. <P>SOLUTION: The group of arrays of protrusions is formed on a glass substrate 18. An interlayer 33 and a semitransmissive film 21 composed of silver alone or an alloy of silver (Ag) coat the group of arrays of protrusions. A color filter 22, an overcoat layer 23, a transparent electrode 24 and an alignment layer 25 are successively formed on the semitransmissive film 21. Also a transparent electrode 26 and an alignment layer 27 are successively formed on a glass substrate 19 and both substrates are stuck to each other with a sealing member 29 via a liquid crystal 28. Furthermore, first and second optical retardation films 30, 31 composed of polycarbonate, etc., and an iodine type polarizing plate 32 are successively formed outside the glass substrate 19. In addition, the interlayer 33 has an orientation surface of a crystal structure conforming to the lattice constant of an orientation surface of the crystal structure of the semitransmissive film 21 within 85 to 115% range. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflective or transflective liquid crystal display device. 2. Description of the Related Art In recent years, liquid crystal display devices have been used for large and high-definition monitors in addition to small or medium-sized portable information terminals and notebook personal computers. Further, a technology of a reflective liquid crystal display device that does not use a backlight has been developed, and is excellent in thinness, light weight, and low power consumption. A reflection type liquid crystal display device includes a scattering reflection type in which a light reflection layer having an uneven shape is formed on the inner surface of a substrate provided behind, but the use of a backlight makes it possible to effectively use ambient light. I use it. Further, a transflective liquid crystal display device of a transflective type in which a transflective film is formed instead of the light reflecting layer, a backlight is provided, and the transflective mode or the transmissive mode is selectively used has been developed. FIG. 11 shows such a scattering-reflection type liquid crystal display device. In the liquid crystal display device 1, a plurality of substantially hemispherical convex portions 3 made of synthetic resin are arranged on a glass substrate 2 to form a convex array group, and a metal array is formed on the convex array group. The light reflecting layer 4 is covered, a color filter 5 is formed on the light reflecting layer 4, an overcoat layer 6 is coated on the color filter 5, and a transparent electrode 7 made of ITO or the like is formed on the overcoat layer 6 in a strip shape. And a plurality of alignment films 8
Is coated. A plurality of transparent electrodes 10 made of ITO or the like are arranged on a glass substrate 9 in a strip shape.
Is coated. Then, both substrates are disposed to face each other with the liquid crystal 12 interposed therebetween, and the liquid crystal 12 is filled in a region surrounded by the sealing member 13, and the first retardation film 14 and the second retardation film 15 and a polarizing plate 16 are sequentially formed. The light reflection layer 4 is formed by coating an Al film by sputtering or the like to increase the light reflectance. On the other hand, when the liquid crystal display device 1 is of a semi-transmission type, Instead of the light reflection layer 4, a semi-transmissive film is used. However, according to the above liquid crystal display device, the convex array group and the light reflection layer 4
And the light reflection layer 4 is peeled off. It is considered that such peeling is caused by the release of moisture and the like from the synthetic resin forming the convex array group. Therefore, as a countermeasure against the peeling, it has been proposed that an SiO ₂ film or the like is formed as an intermediate layer between the convex array group and the light reflecting layer 4 to form an underlayer. In terms of typical performance, it is not yet satisfactory, and further improvement is desired. For example, it has been proposed to use a film made of silver or a silver alloy rather than an Al film in order to lower the light absorptance of the light reflecting layer 4. The relationship between the convex array group and the adhesion between the light reflecting layer 4 and the convex array group has not yet been sufficiently studied. Accordingly, the present invention has been completed in view of the above, and an object of the present invention is to provide a light reflection layer made of silver or a silver alloy, and to provide an adhesion between the convex array group and the light reflection layer. It is an object of the present invention to provide a high-quality and high-reliability liquid crystal display device having improved reliability. According to the liquid crystal display device of the present invention, a convex array group in which a plurality of resin convex portions are randomly arranged is formed on one main surface of a substrate. One member formed by sequentially coating a transparent electrode and an alignment layer on the light reflection film, and the other member formed by sequentially stacking a transparent electrode and an alignment layer on a transparent substrate. Pixels are arranged in a matrix with a nematic liquid crystal interposed between members, and the light reflection layer is made of silver or a silver alloy. The lattice constant of the orientation plane of the crystal structure of the light reflecting film is 85 to 11
The present invention is characterized in that an intermediate layer having a crystal structure oriented plane matching within a range of 5% is interposed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a liquid crystal display of the present invention will be described with reference to the drawings. (Semi-Transmissive Liquid Crystal Display) FIG. 1 is a sectional view of a transflective liquid crystal display for color display according to the present invention.
FIG. 2 is an enlarged sectional view of a main part of one member. In the liquid crystal display device 17 shown in FIG.
18 is a common side glass substrate (0.7 mm thick), 19 is a segment side glass substrate (0.7 mm thick),
For the one member, a random convex array group is formed by arranging a large number of substantially hemispherical convex portions 20 with a resin such as an acrylic resin material on one main surface of the glass substrate 18, As shown in FIG. 2, an intermediate layer 33 and a semi-transmissive film 21 made of silver or a silver alloy as the light reflecting film are coated on the convex array group. In this embodiment, the semi-permeable film 21 is made of silver (A
g) Although it may be either a simple substance or a silver alloy, Ag metal easily reacts with sulfur and chlorine and easily deteriorates. Therefore, it is preferable to stabilize by containing other components for preventing deterioration. For example, there are Pd, Ru, etc., and it is preferable to mix them in a very small amount. If a large amount is mixed, the reflectivity tends to decrease. When Pd is contained, AgxP
When expressed in dy, x = 95.0-99.5, y =
It is good to set to 0.5 to 5.0. The reflectivity at a short wavelength was measured and evaluated by variously changing the amount of Pd added (y value). The results shown in Table 1 were obtained. The corrosion resistance of each sample was also evaluated. Regarding the reflectance at the short wavelength, four kinds of evaluation categories were determined. The mark ◎ indicates that the reflectance did not decrease at all compared to the case where Pd was not added. There is a tendency to decrease, but it is a case where there is no problem in practical use.
The mark indicates a case in which the reflectivity was further reduced, which caused a practical problem. In addition, the corrosion resistance was determined in three evaluation categories. The mark 〇 indicates that the sample did not react with sulfur or chlorine and did not deteriorate at all.
The case where the phenomenon of the reaction appears, and the mark x indicates the case where the phenomenon becomes remarkable. [Table 1] As is clear from this table, it is preferable that the Pd addition amount (y value) is set to be y = 0.5 to 5.0. According to this example, even when Ru is mixed with Ag, x = 95.0-9 expressed by AgxRuy.
It was confirmed by repeated experiments that 9.5 and y = 0.5 to 5.0 should be set. For example, x =
A silver alloy set to 99.0 and y = 1.0 may be used. A color filter 22 made of a resin such as an acrylic resin material is formed on the semi-transmissive film 21. Further, an overcoat layer 2 made of an acrylic resin
3 and a plurality of transparent electrodes 24 made of ITO arranged in parallel
And form. On the transparent electrode 24, an alignment film 25 made of a polyimide resin rubbed in a certain direction is formed. As for the other member, a transparent electrode 26 made of ITO arranged in parallel on a glass substrate 19 and an alignment film 2 made of polyimide resin rubbed in a certain direction.
7 are sequentially formed. An insulating layer made of SiO ₂ may be interposed between the transparent electrode 26 and the alignment film 27. Then, the one member and the other member having the above structure are bonded together by a seal member 29 via a liquid crystal 28 such as STN. Furthermore, a first retardation film 30 made of polycarbonate or the like and a second
A retardation film 31 and an iodine-based polarizing plate 32 are sequentially formed. In the transflective liquid crystal display device 17 having the above configuration, when it is used in the reflection mode, sunlight,
Incident light from external lighting such as fluorescent lamps (arrows shown in Fig. 1)
Passes through the glass substrate 19, reaches the semi-transmissive film 21 through the liquid crystal 28, the color filter 23, and the like.
And the reflected light (arrow shown in FIG. 1) is emitted. For use in the transmission mode, a backlight is provided on the back of the glass substrate 18, and the light emitted from the backlight is a retardation film made of an iodine-based polarizing plate (not shown), polycarbonate or the like. (Not shown), passes through the glass substrate 18, further passes through the semi-transmissive film 21, passes through the color filter 22, the liquid crystal 28, etc.
It is emitted as transmitted light. In the present invention, the intermediate layer 33 has a crystal structure orientation matching within a range of 85 to 115% with respect to the lattice constant of the crystal structure orientation plane of the light reflecting film (semi-transmissive film 21). It is characterized by having a surface. By defining in this way, the convex array group and the semi-permeable film 21 are
3 can be firmly adhered. The intermediate layer 33 is formed of a conductive material such as ITO or a dielectric material such as Al ₂ O ₃ , ZnS, Fe ₂ O ₃ , and TiO ₂ . (Example of Combination of Intermediate Layer 33 and Semi-Transmissive Film 21) In this example, in the semi-transmissive liquid crystal display device 17, the intermediate layer 33 is made of ITO (film thickness of 40 to 110 nm, preferably 80 nm). And the semi-permeable membrane 21 is made of AgPdC
The film was coated with a u alloy, that is, with an atomic composition ratio of Ag _97.5 Pd _1.5 Cu _1.0 with a film thickness of 33 nm. Other configurations are the same. As described above, the reflectance on the short wavelength side is improved by adding Cu to the semi-transmissive film 21 to the AgPd alloy. According to this example, in the case of a binary AgxPdy, x = 95.0-99.5 and y = 0.5-5.0.
It is good to set to (AgxPdy) _1- z
In the case of Cuz, with respect to the composition range of the binary AgxPdy, Cu is preferably set to 0.001 to 0.035 in the entire ternary alloy, whereby a high reflectance can be obtained. I found it easy. As an example, (AgxPdy) ₁ -zCuz
(X = 99.0, y = 1.0), the semi-transmissive film 21 (thickness: 33 nm) is formed by changing the addition amount (z value) of Cu in various ways. Was measured and the reflectance with visible light was measured. The results shown in Table 2 were obtained. [Table 2] Regarding the reflectance at a short wavelength, two kinds of evaluation categories were determined. The mark “〇” indicates a case where the addition of Cu significantly improved, and the mark “△” indicates that the effect was not obtained. Show. Regarding the reflectance with visible light, four evaluation categories were determined. The mark ◎ indicates the case where the highest reflectance was obtained, and the mark 傾向 indicates that the reflectance was slightly decreased. △ indicates that the reflectivity was further reduced, and X indicates that the reflectivity was the lowest. However, these are all characteristics that do not hinder practical use. As is clear from Table 2, Z = 0.001-
It can be seen that when the ratio is 0.035, the reflectance at short wavelengths and visible light is excellent. (Crystal Structure of Intermediate Layer 33 and Semi-Transmissive Film 21) An example of a combination of the above-described intermediate layer 33 and semi-permeable film 21 (intermediate layer 33: ITO, semi-permeable film 21: Ag _97.5 P)
(d _1.5 Cu _1.0 alloy), the intermediate layer 33 has a lattice constant of 85 to the lattice constant of the orientation plane of the crystal structure of the semi-permeable film 21.
It will be described that the alignment of the crystal structure within the range of about 115% enables the convex array group and the semi-permeable film 21 to be firmly adhered to each other with the intermediate layer 33 interposed therebetween. FIG. 3 shows the (400) crystal structure of the intermediate layer 33.
FIG. 4 is a spatial grid diagram showing an orientation plane, and FIG. 4 is a plan view thereof. FIG. 5 is a spatial lattice diagram showing the fcc (111) orientation plane of the crystal structure of the semi-transmissive film 21, and FIG. 6 is a plan view thereof. According to the misfit diagram of the orientation plane shown in FIG. 7, the (400) orientation plane of the ITO film and the AgPdC
The consistency with the fcc (111) orientation plane of the u film is shown, and the numerical values are shown in Table 3. FIG. 7 shows the (400) orientation plane of the ITO film shown in FIG. 4 and the fcc of the AgPdCu film shown in FIG.
It shows the consistency with the (111) orientation plane, and the consistency of the lattice constant is represented by the consistency with the orientation plane or an integral multiple of the orientation plane. In this case, the fc of the AgPdCu film shown in FIG.
Regarding the c (111) orientation plane, the ITO of FIG.
When the consistency with the (400) orientation plane of the film is confirmed, as shown in Table 3, the lattice constant a is 114% and the lattice constant b is 99%. Therefore, consistency is 85
~ 115%, matching. Therefore, by interposing such an ITO base film as an intermediate layer, the adhesiveness between the convex arrangement group and the semi-transmissive film 21 is improved. [Table 3] In comparison of the complete reflectance between the Al film and the AgPdCu film, the reflectance is about 35% for the Al film and 37% for the AgPdCu film, and the reflectance is high. Further, as a comparative example, a liquid crystal display device was used in which the intermediate layer 33 was formed of SiO ₂ instead of ITO and the other components had the same structure. FIG. 8 shows the hcp (1) of the crystal structure of the SiO ₂ film.
01) is a spatial grid diagram showing an orientation plane, and FIG.
The hcp (101) orientation plane of _two films is shown. And FIG.
Is the hcp (101) orientation plane of the SiO ₂ film and AgPdCu
Exhibits consistency with the fcc (111) orientation plane of the film, and
Table 4 shows the numerical values. [Table 4] Further consideration based on the results in the table,
By controlling the orientation of the hcp (101) orientation surface of the SiO ₂ film, the adhesion is improved, but it is considered difficult in practice to control the orientation by forming the SiO ₂ film. In short, for the SiO2 film, hc
It is difficult to orient only the p (101) orientation plane,
There are other orientation planes, which are difficult to improve the adhesion. Next, as shown in the misfit diagram of the orientation plane shown in FIG.
Regarding the consistency with the fcc (111) orientation plane of the gPdCu film, the adhesion due to the change in the consistency as shown in Table 5 with respect to the lattice constant of the orientation plane of the crystal structure of the semi-permeable film 21 in the intermediate layer 33. When the properties were measured, the results shown in Table 5 were obtained. [Table 5] Regarding the adhesion, evaluation criteria are defined in three ways of Δ, Δ, and ×, and the mark ○ indicates a level at which there is no problem in the adhesion after the formation of the intermediate layer, after all the steps in panel fabrication, and in various reliability tests. And when the panel is at a level that can be completed as a panel. The mark “△” indicates a level at which the panel was not completed because the film was peeled off from the intermediate layer in various reliability tests after the formation of the intermediate layer and after all the steps of panel production. × mark, after the formation of the intermediate layer, film peeling from the intermediate layer occurs in the process of panel production, as a panel,
This is an unfinished level. As is evident from Table 5, the intermediate layer 33 has a crystal structure oriented plane that matches within a range of 85 to 115% of the lattice constant of the crystal structure oriented plane of the semi-transmissive film 21. This shows that the panel is completed. It should be noted that the present invention is not limited to the above-described embodiment, and various changes and improvements may be made without departing from the scope of the present invention. For example, in the above description, a semi-transmissive film is used as the light reflecting film. However, instead, a reflective liquid crystal display device using a film with improved light reflectivity also has the same function and effect. As described above, according to the liquid crystal display device of the present invention, a convex array group in which a plurality of resin convex portions are randomly arranged is formed on one main surface of a substrate. One member formed by sequentially coating a transparent electrode and an alignment layer on the light reflection film, and a transparent electrode and an alignment layer are sequentially stacked on a transparent substrate. Pixels are arranged in a matrix with a nematic liquid crystal interposed between the other member and the light reflection layer is made of silver or a silver alloy. In the meantime, the lattice constant of the orientation plane of the crystal structure of the light reflecting film is 85 to 11
A high-quality and highly reliable liquid crystal display device having improved adhesion between the convex array group and the light reflecting layer by interposing an intermediate layer having a crystal structure alignment plane matching within 5% is provided. Could be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a liquid crystal display device of the present invention. FIG. 2 is an enlarged sectional view of a main part of one member according to the liquid crystal display device of the present invention. FIG. 3 is a spatial lattice diagram showing a (400) orientation plane of a crystal structure of an ITO film. FIG. 4 is a plan view showing a (400) orientation plane of a crystal structure of an ITO film. FIG. 5 is a spatial lattice diagram showing the fcc (111) orientation plane of the crystal structure of the AgPdCu film. FIG. 6 is a plan view showing an fcc (111) orientation plane of the crystal structure of the AgPdCu film. FIG. 7 is a diagram showing the consistency between the (400) orientation plane of the ITO film and the fcc (111) orientation plane of the AgPdCu film. FIG. 8 is a perspective view showing an hcp crystal structure of a SiO ₂ film. FIG. 9 is a view showing an atomic arrangement in an hcp (101) orientation plane of a SiO ₂ film. FIG. 10 shows the hcp (101) orientation plane of the SiO ₂ film and Ag.
FIG. 6 is a diagram showing the consistency with the fcc (111) orientation plane of the PdCu film. FIG. 11 is a sectional view of a conventional liquid crystal display device. [Description of Signs] 17 ... Liquid crystal display devices 18 and 19 ... Glass substrate 20 ... Protrusion 21 ... Semi-transmissive film 22 ... Color filters 24 and 26 ... Transparent electrodes 25 and 27 ... Alignment film 28 ... Liquid crystal 29 ... Seal member 33 ... Intermediate layer

Claims (1)

Claims: 1. A convex array group in which a plurality of resin-made convex portions are randomly arranged is formed on one principal surface of a substrate, and a light reflecting film is coated on the convex array group. Then, a nematic liquid crystal is interposed between one member formed by sequentially laminating a transparent electrode and an alignment layer on the light reflecting film and the other member formed by sequentially laminating a transparent electrode and an alignment layer on a transparent substrate. A liquid crystal display device in which pixels are arranged in a matrix with interposition, wherein the light reflection layer is made of silver or a silver alloy, and the light reflection layer is provided between the convex arrangement group and the light reflection film. A liquid crystal display device comprising an intermediate layer having an alignment plane having a crystal structure that matches within a range of 85 to 115% of a lattice constant of an alignment plane having a crystal structure of a film.