JP2000187106A - Semitransmissive reflecting plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a semitransmissive reflecting plate having sufficiently high utilization efficiency of light by disposing a 1st layer of an inorganic dielectric having a specified refractive index and a 2nd layer of metal having a specified thickness on the surface of a light transmissive substrate. SOLUTION: This semitransmissive reflecting plate has a 1st layer of an inorganic dielectric having a refractive index of 2.2-2.5 and 0.2λ-0.3λ thickness and a 2nd layer of metal having 30-300 Å thickness on a light transmissive substrate in order from the substrate side toward the air layer side. The reflecting plate has ruggedness on one or both faces so as to impart a light diffusing property. The inorganic dielectric forming the 1st layer may be any inorganic dielectric having a refractive index of 2.2-2.5 and capable of forming a layer which transmits visible light and TiO2 or ZnS having a refractive index of >=2.3 is preferably used. The metal forming the 2nd layer is preferably metal capable of giving a slightly colored layer and Al, Ag or Cr that ensures slight coloration and has a high reflectance is preferably used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a semi-transmissive reflector.

[0002]

2. Description of the Related Art Conventionally, a reflection type liquid crystal display device is thin,
It has been used for display devices such as calculators and watches requiring low power consumption. 2. Description of the Related Art In recent years, image quality has been improved and colorization has been promoted, and it has been used for portable information terminals and the like, and the use of reflective liquid crystal display devices has been rapidly expanding.

[0003] Since these reflective liquid crystal display devices use external light for display, the display cannot be seen in a dark place. A transflective liquid crystal display device having both the characteristics of a reflective liquid crystal display device and a transmissive liquid crystal display device is used so that a display can be viewed even when there is no external light. This transflective liquid crystal display device can be used in a reflection mode in which a transflective plate having transflective properties is disposed on the back side of the liquid crystal display element to reflect light from the front of the liquid crystal display element. In addition, when the outside is dark, it can be used in a transmission mode in which a backlight disposed on the back side of the semi-transmissive reflection plate is turned on and display is performed by light transmitted through the semi-transmissive reflection plate.

However, the light use efficiency (sum of the transmittance and the reflectance) of the transflective plate used in such a transflective liquid crystal display device is not always 100%, so that the reflective mode and the transmissive mode are used. However, it was not possible to obtain a bright display.

[0005]

Therefore, the present inventor has proposed:
We are keenly studying to develop a transflective reflector that has high light utilization efficiency and can provide a display with sufficient brightness in both transflective and transmissive modes in transflective liquid crystal display devices. As a result, the transflective plate obtained by providing the first layer having a specific refractive index and the second layer made of a metal having a specific thickness on the surface of the base material has a transflective plate with sufficiently high light use efficiency. The present inventors have found that it is a plate, and have reached the present invention.

[0006]

That is, according to the present invention, a refractive index is 2.2 to 2.5 and a thickness is 0 on a light transmitting substrate in order from the light transmitting substrate side to the air layer side. .2λ to 0.3λ
A first layer made of an inorganic dielectric material having a thickness of 30 to 300
And a second layer made of a metal (1).

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The translucent substrate used for the translucent reflector of the present invention is:
It may be plate-shaped, film-shaped,
It may be in the form of a sheet. The light-transmitting substrate is not particularly limited as long as it is light-transmitting. For example, a cellulose-based polymer, a polycarbonate-based polymer, a polyarylate-based polymer, a polyester-based polymer, an acrylic-based polymer, and functional norbornene Polymer, polysulfone,
Substrates made of resin such as polyethersulfone, glass substrates, and the like can be given. In addition, an optical component on a plate, a film, or a sheet such as a polarizing plate or a light guide plate for a backlight can be used as the substrate.

The translucent substrate has an inorganic dielectric material on its surface.
Having an intermediate layer for improving adhesion to the first layer made of
May be. As the intermediate layer, for example, an acrylic tree
Fat, urethane resin, silicon resin, cardo resin,
Polymer membranes composed of polymers such as lysilazane
You. In addition, SiO having a thickness of about 30 to 200 mm is used._x, Al_Two
O _ThreeUse of an inorganic dielectric layer such as
Both are possible. Form inorganic dielectric layer on translucent substrate
The surface may be subjected to a surface treatment. About surface treatment method
Although not particularly limited, heat treatment in a vacuum, roller
Treatment, ion bombardment treatment, plasma treatment, ultraviolet light
Irradiation, ultraviolet irradiation and the like can be exemplified.

For the purpose of imparting light diffusing properties, the semi-transmissive reflecting plate may be one having unevenness on one or both sides. The unevenness can be provided by, for example, a method of providing a layer in which silica gel, resin beads, glass beads, or the like are dispersed in a resin, an etching treatment, a mat treatment, or the like.

The inorganic dielectric constituting the first layer made of an inorganic dielectric may be any inorganic dielectric having a refractive index of 2.2 to 2.5 and capable of forming a layer transparent to visible light. In particular, TiO ₂ having a refractive index of 2.3 or more (refractive index of 2.3
3), ZnS (having a refractive index of 2.37) and the like are preferable.

The first layer needs to have a thickness of 0.2λ to 0.3λ, particularly preferably 0.23 to 0.2λ.
7λ. Here, λ is a design wavelength, and when used in a liquid crystal display device, is usually set arbitrarily from a wavelength range of 500 nm to 600 nm, and is generally set to 550 nm.

The metal constituting the second layer made of a metal is preferably a metal capable of providing a layer with little coloring, and among them, Al, Ag, Cr, etc., with little coloring and high reflectivity, are particularly preferably used. The thickness of the second layer needs to be in the range of 30 ° to 300 ° from the viewpoint of translucency. When the second layer made of metal is easily oxidized by air or easily eroded by an adhesive layer, a protective layer may be provided on the second layer. Examples of the protective layer include a SiO _x layer.

The first layer and the second layer are formed by, for example, electron beam evaporation, induction heating evaporation, resistance heating evaporation,
It can be provided over a light-transmitting substrate by a method such as a sputtering method. As an apparatus for manufacturing the first layer and the second layer, a manufacturing apparatus such as a batch type or an in-line type is used when the light-transmitting substrate has a plate shape or a sheet shape. When the light-transmitting substrate is in the form of a film, a roll-up type vacuum film forming apparatus can be used.

This semi-transmissive reflector can be used as a diffusive semi-transmissive reflector in combination with a light-diffusing layer for the purpose of imparting light diffusing properties as required. As a method of combination, a method in which a layer in which silica gel, resin beads, glass beads, and the like are dispersed in a resin is provided on a semi-transmissive semi-reflective plate, a film in which a layer in which silica gel, resin beads, glass beads, and the like are dispersed in a resin are formed, Etching treatment,
A method in which a film with an uneven surface formed by a mat treatment or the like is laminated on a semi-transmissive reflector via an adhesive layer, and a light-diffusive adhesive layer in which resin beads, glass beads, etc. are dispersed is placed on the semi-transparent reflector. And the like.

This transflective reflector can be used as a transflective reflector in combination with a polarizer layer. As a combination method, there is a method of forming a semi-transmissive reflective layer thereon using a polarizing plate on a light-transmitting substrate, a method of laminating this semi-transmissive reflective plate with a polarizing plate via an adhesive layer, and the like. .

[0016]

The translucent reflector of the present invention has a high light utilization efficiency and, when mounted on a transflective liquid crystal display, provides a bright display in both the reflection mode and the transmission mode. be able to.

[0017]

EXAMPLES The present invention will be described in more detail with reference to Examples.
The present invention is not limited to these examples.

The evaluation of the obtained semi-transmissive reflective film was performed as follows. "UV-220" manufactured by Shimadzu Corporation
Using “0”, the reflection spectrum (absolute reflectance) and the transmission spectrum were measured, and the light utilization efficiency (the sum of the reflectance R and the transmittance T) at the wavelength of 550 nm with the highest visibility was evaluated.

Example 1 Triacetyl cellulose film (trade name: Fuji TAC)
A transparent polymer film in which an acrylic resin film having a thickness of about 5 μm is formed on SH-80 (manufactured by Fuji Photo Film Co., Ltd.) is used as a light-transmitting substrate, and a ZnS layer (refractive index: 2.37, thickness: 580 °), Ag layer (refractive index 0.05
5, a thickness of 200 °) was sequentially formed to obtain a semi-transmissive reflector. Each layer was applied under the following conditions.
The light-transmitting substrate was set in a holder in a vacuum evaporation machine, and after evacuating to a pressure of 2 × 10 ⁻⁵ Torr, the electron gun output was 1.5.
Using KW and a deposition material (ZnS), a ZnS layer having a thickness of 580 ° was formed by a vacuum deposition method. Subsequently, an Ag layer having a thickness of 200 ° was formed by a vacuum deposition method using 3.5 KW of electron gun output and Ag as a deposition material. FIG. 1 shows the reflection spectrum and transmission spectrum of the obtained semi-transmissive reflector.
Shown in The light use efficiency of this semi-transmissive reflector was 97%.

Example 2 Triacetyl cellulose film (trade name: Fuji TAC)
A transparent polymer film in which an acrylic resin film having a thickness of about 5 μm was formed on SH-80 (manufactured by Fuji Photo Film Co., Ltd.) was used as a light-transmitting substrate, and a ZnS layer (refractive index 2.43, thickness 580 °) was used as the substrate. ), Cr layer (refractive index 2.38,
A thickness of 50 °) was sequentially formed to obtain a semi-transmissive reflector. Each layer was applied under the following conditions. Place the translucent substrate in the holder in the vacuum evaporation machine and set the pressure to 2 × 1
After exhausting to 0 ^-5 Torr, the electron gun output was 1.5 KW,
Using a vapor deposition material (ZnS), a thickness of 5
An 80 ° ZnS layer was formed. Then the electron gun output 1.8
Using KW and Cr as a deposition material, a Cr layer having a thickness of 50 ° was formed by a vacuum deposition method. FIG. 2 shows the reflection spectrum and transmission spectrum of the obtained semi-transmissive reflector. The light use efficiency of this semi-transmissive reflector was 89%.

Comparative Example 1 Triacetyl cellulose film (trade name: Fuji TAC)
A transparent polymer film having an acrylic resin film having a thickness of about 5 μm formed on SH-80 Fuji Photo Film Co., Ltd. was used as a light-transmitting substrate, and an Al layer (refractive index: 0.76, thickness: 50 °) was further formed to obtain a semi-transmissive reflector. The Al layer was formed under the following conditions. The substrate was set on the holder in the vacuum evaporation machine, and the pressure was 2 × 10
After exhausting to ^-5 Torr, the electron gun output was 3.5 KW, and the thickness was 50 by a vacuum evaporation method using Al as an evaporation material.
An Al layer of Å was formed. FIG. 3 shows the reflection spectrum and transmission spectrum of the obtained semi-transmissive reflector. The light use efficiency of this semi-transmissive reflector was 80%.

[Brief description of the drawings]

FIG. 1 is a graph showing a spectral reflectance and a spectral transmittance of a semi-transmissive reflector obtained in Example 1.

FIG. 2 is a graph showing a spectral reflectance and a spectral transmittance of a semi-transmissive reflector obtained in Example 2.

FIG. 3 is a graph showing the spectral reflectance and the spectral transmittance of the semi-transmissive reflector obtained in Comparative Example 1.

Continued on the front page (72) Inventor Nobuyuki Kurata 2-10-1, Tsukahara, Takatsuki-shi, Osaka Sumitomo Chemical Company, Ltd. F-term (reference) 2H042 DA02 DA03 DA04 DA11 DA12 DA14 DA15 DA18 DA21 DB01 DC02 DE00 2H091 FA08X FA08Z FA15Z FB06 FB08 FC18 FC23 FC25 FC26 FC27 FD06 FD14 GA17 KA01 LA03

Claims (8)

[Claims] 1. An inorganic dielectric having a refractive index of 2.2 to 2.5 on a light-transmitting substrate in order from the light-transmitting substrate side to the air layer side. A semi-transmissive reflector comprising: a first layer having a wavelength of 3λ; and a second layer made of metal and having a thickness of 30 to 300 °. 2. The semi-transparent reflector according to claim 1, wherein the inorganic dielectric is ZnS or TiO ₂ . 3. The method according to claim 1, wherein the second layer made of a metal is Al, Ag or C.
The transflective plate according to claim 1 or 2, which is a layer made of r. 4. The transflective plate according to claim 1, wherein the transparent substrate has irregularities on one or both sides. 5. The translucent reflector according to claim 1, wherein the translucent substrate is a polarizing plate. 6. A diffusive transflective plate having an adhesive layer in which a light diffusing substance is dispersed on one or both surfaces of the transflective plate according to claim 1. 7. A transflective reflective polarizing plate, wherein the transflective reflector according to claim 1 is laminated on a polarizing plate. 8. A liquid crystal display device incorporating the semi-transmissive reflection plate according to claim 1.