JPH10239679A - Light shielding film structure and liquid crystal display device using the structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the reflection factor of a light shielding film lower for a liquid crystal display device. SOLUTION: A light shielding film 12 having a three-layered structure formed by laminating a Cr layer 12a, a CrO layer 12b, and a Cr layer 12c in this order is allowed to have a lower reflection factor in comparison with a light shielding film having a two-layered structure formed by laminating a Cr layer and a CrO layer in this order. A glare preventing function (anti-glare) layer 18 is provided on the upper face of a polarizing plate 17 provided on the upper face of an upper glass substrate 11 having the light shielding film 12 having this three-layered structure with an adhesive layer between them. This constitution and a constitution where an anti-reflection layer consisting of plural layers each of which consists of SiO2 /TiO2 is additionally provided on the upper face of the glare preventing function layer 18 gave an approximately equal reflection factor over all wavelength bands. Consequently, the reflection factor is made sufficiently lower even if the anti-refection layer is omitted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light shielding film structure and a liquid crystal display using the same.

[0002]

2. Description of the Related Art FIG. 4 is a sectional view showing a part of an example of a conventional liquid crystal display device. This liquid crystal display device includes a lower glass substrate 1 and an upper glass substrate 11. Pixel electrodes 2 made of ITO and thin film transistors 3 as switching elements are provided in a matrix on the upper surface of a lower glass substrate 1, and an overcoat film 4 made of silicon oxide or silicon nitride is provided on the entire upper surface. Is provided with an alignment film 5 made of polyimide. A polarizing plate 7 is provided on the lower surface of the lower glass substrate 1 via an adhesive layer 6.

On the lower surface of the upper glass substrate 11, a Cr layer 12a is provided.
Light-shielding film 12 formed by laminating a CrO layer 12b in this order.
Are provided in a lattice shape, and red, green, and blue color filter elements 13 are provided on the lower surface thereof.
A common electrode 14 made of O is provided, and an alignment film 15 made of polyimide is provided on a lower surface thereof. A polarizing plate 17 is provided on an upper surface of the upper glass substrate 11 with an adhesive layer 16 interposed therebetween, and an anti-glare function (anti-glare) layer 1 is provided on the upper surface.
8 and an antireflection layer 19 is provided on the upper surface thereof. Among them, the antiglare layer 18 is formed by dispersing a large number of light scattering particles made of silica or the like in a transparent layer made of a transparent resin provided on the upper surface of the polarizing plate 17,
For example, it has a function of scattering external light such as a fluorescent light reflected on the polarizing plate 17 and blurring the outline. The anti-reflection layer 19 is composed of a plurality of layers of SiO ₂ / TiO ₂ as one layer. The lower glass substrate 1 and the upper glass substrate 11 are bonded to each other via a sealing material (not shown). Liquid crystal 21 is sealed between the alignment films 5 and 15 of both glass substrates 1 and 11 inside the sealing material.

[0004]

By the way, the light shielding film 12
Has a two-layer structure of the Cr layer 12a and the CrO layer 12b, because the reflectance can be reduced to about 3% when the Cr layer 12a alone has a reflectance of about 5%. However, it cannot be lower than about 3%. Therefore, conventionally, as described above, the antireflection layer 19 is further provided. However, the antireflection layer 1
9 is composed of a plurality of layers (for example, five layers or six layers) having one layer of SiO ₂ / TiO ₂ , and thus has a problem of high cost. Incidentally, compared with the case where only the anti-glare function layer 18 is provided on the upper surface of the polarizing plate 17, it is about five times higher. A first object of the present invention is to further reduce the reflectance of a light shielding film. A second object of the present invention is to omit the antireflection layer.

[0005]

According to a first aspect of the present invention, there is provided a light-shielding film structure comprising a Cr layer and a CrO layer on one surface of a transparent substrate.
The light-shielding film has a three-layer structure in which a layer and a Cr layer are laminated in this order. 4. The liquid crystal display device according to claim 3, wherein a liquid crystal is sealed between two transparent substrates bonded to each other, wherein the back surface of the transparent substrate on the front surface side of the two transparent substrates. , Cr layer, C
The light-shielding film has a three-layer structure in which an rO layer and a Cr layer are laminated in this order. A liquid crystal display device according to a fifth aspect of the present invention is the liquid crystal display device according to the third aspect, wherein a polarizing plate and an anti-glare function layer are provided in this order on a surface of the transparent substrate on the front surface side.

According to the first or third aspect of the present invention, when the light shielding film has a three-layer structure of a Cr layer, a CrO layer, and a Cr layer,
The reflectance can be further reduced as compared with the case of the two-layer structure of the Cr layer and the CrO layer. By the way, when the light shielding film has a three-layer structure of a Cr layer, a CrO layer, and a Cr layer,
The reflectance can be 1% or less. As a result, the polarizing plate and the anti-glare function layer are provided in this order on the surface of the transparent substrate on the front side, and the reflectance is sufficiently reduced even if the anti-reflection layer is omitted. be able to.

[0007]

FIG. 1 is a sectional view showing a main part of a liquid crystal display device according to an embodiment of the present invention.
In this figure, the same parts as those in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted as appropriate. This liquid crystal display device is different from the conventional example shown in FIG. 4 in that a Cr layer 12a and a Cr layer 12a are formed on the lower surface (back surface) of an upper glass substrate (transparent substrate) 11.
An O layer 12b and a Cr layer 12c are laminated in this order.
Only the anti-glare function layer 18 is provided on the upper surface of the polarizing plate 17 provided on the upper surface (front surface) of the upper transparent substrate 11 via the adhesive layer 16, The point is that the antireflection layer 19 is omitted.

Next, the result of an experiment on the reflectance of a light-shielding film or the like will be described. First, a Cr layer and a CrO
A light-shielding film having a three-layer structure formed by laminating a layer and a Cr layer in this order was prepared (hereinafter referred to as the present sample).
In this case, each layer thickness of the Cr layer, the CrO layer and the Cr layer is 50
It was about 0 to 600 °. For reference, a glass substrate without a light-shielding film was also prepared (hereinafter, referred to as a glass substrate).
It is called a reference sample. ). Further, for comparison, a light-shielding film having two structures formed by laminating a Cr layer and a CrO layer in this order on the upper surface of a glass substrate was prepared (hereinafter referred to as a comparative sample). Also in this case, the thickness of each of the Cr layer and the CrO layer was about 500 to 600 °.

When the reflectances of the sample, the reference sample, and the comparative sample were examined, the results shown in FIG. 2 were obtained.
In FIG. 2, the solid line indicates the reflectance of the present sample, the dashed line indicates the reflectance of the reference sample, and the dotted line indicates the reflectance of the comparative sample. As is clear from FIG. 2, the reflectance of the sample shown by the solid line is lower than the reflectance of the comparative sample shown by the dotted line. In addition, the reflectance of the comparative sample indicated by the dotted line is particularly 450
While the reflectance sharply increases in a low wavelength band of less than nm, the reflectance of the sample shown by a solid line is almost constant in the entire wavelength band. Further, the reflectance of the light shielding film itself having a three-layer structure, which is obtained by subtracting the reflectance of the reference sample shown by the dashed line from the reflectance of the sample shown by the solid line, is 1% or less. As described above, if the light-shielding film has a three-layer structure of a Cr layer, a CrO layer, and a Cr layer, C
The reflectance can be further reduced as compared with the case of the two-layer structure of the r layer and the CrO layer.

Next, a description will be given of experimental results of the reflectance depending on the presence or absence of the antireflection layer. First, a Cr layer, a CrO layer, and a Cr layer are laminated on one surface of a glass substrate in this order.
A light-shielding film having a layered structure was formed, and a polarizing plate provided with an adhesive layer on the other surface and an anti-glare function layer provided on the upper surface was prepared (hereinafter referred to as the present sample). In addition, a light-shielding film having a three-layer structure in which a Cr layer, a CrO layer, and a Cr layer are laminated in this order on one surface of the glass substrate is formed.
A polarizing plate having an antiglare function layer and an antireflection layer provided in this order on an upper surface of a polarizing plate provided with an adhesive layer on the other surface was prepared (hereinafter referred to as a comparative sample).

When the reflectances of the present sample and the comparative sample were examined, the results shown in FIG. 3 were obtained. In FIG. 3, a solid line indicates the reflectance of the present sample, and a dotted line indicates the reflectance of the comparative sample. As is clear from FIG. 3, the reflectance of the sample shown by the solid line is almost the same as the reflectance of the comparative sample shown by the dotted line in the entire wavelength band. Therefore, even if the anti-reflection layer is omitted, the reflectance can be sufficiently reduced, and the cost can be reduced.

In the above embodiment, the upper glass substrate 1
1, a light-shielding film 12 having a three-layer structure in which a Cr layer 12a, a CrO layer 12b, and a Cr layer 12c are laminated in this order.
Has been described, but is not limited thereto.
A light-shielding film having a multilayer structure of four or more layers in which layers and CrO layers are alternately stacked may be provided.

[0013]

As described above, according to the present invention, the light-shielding film has a structure of three or more layers by alternately laminating the Cr layer and the CrO layer. Therefore, the two-layer structure of the Cr layer and the CrO layer is provided. The reflectance can be further reduced as compared with the case of. For example, when the light-shielding film has a three-layer structure of a Cr layer, a CrO layer, and a Cr layer, the reflectance can be 1% or less. As a result, the polarizing plate and the anti-glare function layer are provided in this order on the surface of the transparent substrate on the front side, and the reflectance is sufficiently reduced even if the anti-reflection layer is omitted. And thus the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating the reflection characteristics of a light-shielding film having a three-layer structure and a two-layer structure.

FIG. 3 is a view for explaining reflection characteristics depending on the presence or absence of an antireflection layer.

FIG. 4 is a partial cross-sectional view of an example of a conventional liquid crystal display device.

[Explanation of symbols]

 Reference Signs List 1 lower glass substrate 11 upper glass substrate 12 light shielding film 12a Cr layer 12b CrO layer 12c Cr layer 17 polarizing plate 18 antiglare function layer 21 liquid crystal

Claims (5)

[Claims] 1. A light-shielding film structure comprising a three-layer light-shielding film in which a Cr layer, a CrO layer, and a Cr layer are laminated in this order on one surface of a transparent substrate. 2. A light-shielding film structure comprising: a light-shielding film having a multilayer structure of four or more layers in which Cr layers and CrO layers are alternately stacked on one surface of a transparent substrate. 3. A liquid crystal display device in which liquid crystal is sealed between two transparent substrates bonded to each other, wherein a Cr layer is formed on the back surface of the front transparent substrate of the two transparent substrates.
A liquid crystal display device comprising a three-layer light-shielding film in which a CrO layer and a Cr layer are laminated in this order. 4. A liquid crystal display device in which liquid crystal is sealed between two transparent substrates bonded to each other, wherein a Cr layer and a CrO layer are formed on the back surface of the front transparent substrate of the two transparent substrates. A light-shielding film having a multilayer structure of four or more layers in which are alternately stacked. 5. The invention according to claim 3, wherein
A liquid crystal display device comprising a polarizing plate and an anti-glare functional layer provided in this order on the surface of the transparent substrate on the front side.