JP2003084139A - Hologram reflector and reflection type liquid crystal display device equipped with the same - Google Patents

Abstract

(57) [Abstract] [Problem] To be able to view display light without using an illumination light source built into the device even in a situation where ambient light is small,
A hologram reflection plate suitable for realizing a reflection type liquid crystal display device with low power consumption (or a display light by a hologram reflection plate using a volume phase transmission hologram under a situation where ambient light is sufficient is yellowish). A hologram reflector which solves the problem and realizes display light close to white) and a liquid crystal display device using the same. In a situation where ambient light is sufficient, the device has a light storage function,
In a situation where the amount of ambient light is small, a material having a self-luminous function (hereinafter, referred to as a light storage substance) is provided at any part of the hologram reflector.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a hologram reflection plate which realizes control of a direction / range (viewing area) where display light can be viewed brightly by using a hologram. The technical field in which a hologram reflector is used is a reflective liquid crystal display device that does not require a special light source such as a backlight or an edge light and uses reflected light from ambient light (sunlight or indoor lighting) as display light. Typical applications include watches and mobile phones.

[0002]

2. Description of the Related Art A reflection type liquid crystal display device has a structure in which a reflection layer for reflecting ambient light is provided on the back surface of a liquid crystal panel (on the side opposite to an observer). The display pattern is defined when passing through the panel,
It is emitted to the observer side and is visually recognized as display light. Various attempts have been made to adopt a hologram as the reflective layer, instead of the existing metal reflective layer, which will be exemplified below.
The advantage of adopting a hologram is that the amount of reflected light can be increased in a direction other than the regular reflection direction, so that bright display light can be viewed from a direction different from the reflection on the large device surface (glass) in the regular reflection direction. Ambient light incident from various directions can be effectively contributed as display light (light from various directions can be diffracted in the same direction), and a brighter display light can be obtained, the viewing area and the reflection direction. Since it is possible to control, it is possible to achieve bright display in a specific direction.

As described in Japanese Patent Publication No. 8-505716, a reflection hologram is used, and as described in Japanese Patent No. 2854986 and Japanese Patent Application Laid-Open No. 10-142424, a transmission hologram is used. It has been proposed to use it as a reflective layer in combination with a metal reflective layer. It is also known that the metal reflective layer is a semi-transmissive type, and the illumination light source built in the liquid crystal display device is used as an auxiliary so that the display light can be viewed even when there is no ambient light.

When a volume phase reflection type hologram is used, since the wavelength width for reflection and diffraction is narrow due to its wavelength selectivity, colored (specific color other than white or silver) reflected light is visible and wide. It is difficult to realize a bright display in the visible wavelength range. When a volume phase transmission type hologram is used, the hologram has almost no wavelength selectivity and the diffracted light has a wide wavelength width over the visible range, so that display light close to white can be realized. When a hologram reflection plate using a volume phase transmission type hologram is applied to a display device, white display light is realized. Therefore, by using a (known) color filter in the display device together, a full color image can be obtained. Is suitable for displaying.

In any case, even if an attempt is made to observe a display in an environment (dark place / time) where there is little ambient light, the amount of incident light on the hologram is small, so that the amount of display light that reaches the observer is inevitably reduced. Will be difficult. Further, even when the ambient light is sufficient, when the volume phase transmission hologram is used as the hologram that constitutes the hologram reflection plate, the hologram has almost no wavelength selectivity and displays a display light close to white. In fact, absorption of materials, diffracted light, ambient light and illumination light from inside the device, and some of the metals used for the reflective layer have a low reflectance in the near-ultraviolet region (~ 500 nm). Therefore, the display light may be yellowish.

As described above, it is also known that the display light can be visualized even when there is no ambient light by using the illumination light source built in the liquid crystal display device as an auxiliary. In the device, illumination light has the largest loss in terms of power consumption, and it is hard to say that it is a good idea from the viewpoint of energy saving.

[0007]

SUMMARY OF THE INVENTION According to the present invention, since the display light can be viewed without auxiliary use of the illumination light source built in the liquid crystal display device even in a situation where the ambient light is small, the reflective type consumes less power. The main object of the present invention is to provide a hologram reflector suitable for realizing a liquid crystal display device. Further, even in a situation where the ambient light is sufficient, in the hologram reflection plate using the volume phase transmission hologram, as described above,
It is an object of the present invention to provide a hologram reflector which realizes display light closer to white (paper white) and a liquid crystal display device using the hologram reflector, which solves the problem that the display light may be yellowish.

[0008]

According to the present invention, a material having a light-storing function when the ambient light is sufficient and a self-luminous function when the ambient light is small (hereinafter referred to as a light-storing substance).
The above-mentioned object is achieved by providing the hologram reflection plate at any position. That is, the present invention according to claim 1 is a hologram reflection plate in which a light reflection layer is formed on one surface of a volume phase hologram layer, and a layer containing a phosphorescent substance is arranged between the hologram layer and the light reflection layer. A hologram reflection plate having the above-mentioned configuration.

The hologram reflection plate according to claim 2 is a hologram reflection plate having a light reflection layer formed on one surface of a volume phase hologram layer, wherein the hologram layer on the side where the light reflection layer is not formed is It is characterized in that a layer containing a phosphorescent substance is arranged.

According to a third aspect of the present invention, there is provided a hologram reflection plate in which a light reflection layer is formed on one surface of a volume phase hologram layer, wherein the hologram layer has a luminous material dispersed in a photosensitive material. It is characterized in that

According to a fourth aspect of the present invention, there is provided a hologram reflection plate in which a light reflection layer is formed on one surface of a volume phase hologram layer, wherein the light reflection layer disperses a light reflection filler and a phosphorescent substance. It is characterized in that it is formed by applying and forming the ink.

According to a fifth aspect of the present invention, in the hologram reflector, the layer containing the phosphorescent substance is a film formed by coating the surface thereof with an ink containing the phosphorescent substance dispersed therein or an ink containing the phosphorescent substance dispersed therein. Characterize.

The volume phase hologram layer may be either a volume phase reflection type hologram or a volume phase transmission type hologram, but particularly in the case of a volume phase transmission type hologram,
As described above, since there is a problem that the display light is visually yellowish, the phosphorescent substance is a fluorescent whitening agent that strongly emits light in the visible to blue wavelength range. Blue ~
Since (purple) has a complementary color relationship, the influence of each other is canceled out, and the display light can be viewed as preferable white.

When a polarizing film is further laminated on the outermost surface of the hologram layer on the side where the light reflecting layer is not formed, the hologram reflecting plate is a system in which polarizing plates are indispensable on the front and back (upper and lower) of the liquid crystal panel. Since the hologram reflection plate also serves as the lower polarizing plate of the liquid crystal display device (type using TN type liquid crystal), the liquid crystal display device can be easily assembled, which is advantageous when incorporated into the device.

The light reflection layer formed on one surface (back surface) of the volume phase hologram layer is often a film (sheet) -like structure composed of a base material and a reflection layer. As the base material,
Either a light-scattering property or a high transparency may be used, but a plastic film (TAC, PEN, PC, acrylic, etc.) having excellent smoothness represented by a polyester film is used.

The reflective layer is formed by vapor-depositing aluminum, silver, chromium, nickel or the like on the surface of the base material, or by coating an ink containing a reflective filler.

As described in claims 1 to 4, the layer containing the phosphorescent substance may take various arrangements as appropriate, but the structure of claim 1 (light reflecting layer / phosphorescent substance layer / hologram layer). In particular, when the light reflection layer is composed of a metal vapor deposition layer, if the hologram made of the photosensitive material and the metal vapor deposition layer are in direct contact with each other, the surface of the metal vapor deposition layer is easily deteriorated. It will also serve as a protection.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. <Light-Reflecting Layer> A light-reflecting layer is formed on the polyester film substrate by coating or vapor deposition.

<Luminescent Material Layer> In the present embodiment, a case of a layer structure composed of a light reflecting layer / a luminescent material layer / a hologram layer will be described. A layer containing a fluorescent material having a light-transmitting property is formed as a light-storing substance on the light reflection layer. When a fluorescent whitening agent is also used in the fluorescent material, the fluorescent brightening agent is added to the resin in an amount of 0.
Mix about 1% and coat. Further, when a luminous paint is used as the fluorescent material, a luminous pigment, clear (adhesive) and the like are mixed and coated in the form of paint.
From the above, a fluorescent reflective film (a film having a reflective layer having a layer containing a fluorescent material) is obtained. Examples of the optical brightening agent include 2,5 bis (5′-tert-butylbenzoxazolyl (2)) thiophene, and examples of the luminescent pigment include:
ZnS: Cu is exemplified.

<Volume Phase Transmission Hologram> In this embodiment, the case of using a volume phase transmission hologram as a hologram will be described. The volume phase transmission hologram can be photographed and recorded on the photosensitive material for volume phase hologram by using an ordinary two-beam hologram photographing optical system. Examples of the light-sensitive material include gelatin dichromate, silver salt light-sensitive material, and photopolymer. As an example, a silver salt photosensitive material for hologram 8E56 manufactured by AGFA
A film or a photo polymer HRF600 manufactured by DuPont can be used.

In photographing and recording a hologram, a well-known photographing and recording method is used, and a diffuser plate (frosted glass) is used as a subject.
Image recording is performed on the above-mentioned various light-sensitive materials. In order to obtain white diffracted light, if the light-sensitive material is a silver salt, CWC2
After developing with a developing solution, bleaching with a PBQ2 bleaching solution, washing with water and drying, and in the case of HUF600 manufactured by DuPont, after heat development, bleaching with ultraviolet rays is carried out. Obtain a volume phase transmission hologram.

FIG. 1 is an explanatory view (cross-sectional view) showing an outline of an example of the structure of a reflection type liquid crystal display device using the hologram reflection plate of this embodiment.

The fluorescent reflection film A has a structure in which a metal vapor deposition layer to be the light reflection layer 8 is formed on one surface of a base material 10, and a translucent fluorescent layer 9 is formed on this vapor deposition surface. The hologram reflection plate B has a structure in which the volume phase transmission hologram layer 6 and the polarizing plate 4 are further laminated on the fluorescent reflection film A, and is arranged on the back surface of the liquid crystal panel 2. The fluorescent reflection film A and the polarizing plate 4 are bonded and integrated with the hologram layer 6 via an adhesive. As a result, the front polarizing plate 3 and the rear polarizing plate 4 are arranged on the front and back of the liquid crystal panel 2, respectively.

The visual description of the liquid crystal display device in a situation where the ambient light is sufficient is explained as follows. Illumination light 11
When incident ambient light enters the liquid crystal display device, first, only the light of the polarization component in one direction is polarized by the first polarizing plate 3.
And reaches the second polarizing plate 4 after being rotated according to the display pattern on the liquid crystal panel 2.

The light transmitted through the second polarizing plate 4 is incident on the volume phase transmission type hologram layer 6, and this hologram 6 has an angle selectivity, and depending on the angle selectivity of the hologram 6. Then, the incident light passes through the hologram 6 without being diffracted.

The light 7 transmitted through the hologram 6 reaches an arbitrary translucent fluorescent layer 9 formed on the back surface of the hologram 6, and the fluorescent component fluoresces with light having a specific excitation wavelength. Light having a wavelength other than the specific wavelength is specularly reflected by the light reflecting layer 8, passes through the translucent fluorescent layer 9 again, and enters the hologram 6.

The incident light 12 at this time is the first incident light 7
Is incident on the hologram 6 at an angle of incidence opposite to that of positive and negative, but this coincides with the angle selectivity of the hologram 6, and this time it is diffracted and emitted as diffracted light 13 at a specific angle. Diffracted light 1
3 again passes through the polarizing film 4, the liquid crystal panel 2 and the polarizing film 3 and reaches the eyes 14 of the observer as pattern display light.

In the above description, the ambient light incident on the display device is not diffracted when it first passes through the hologram,
Although the description has been given of the case where the hologram is diffracted when passing through the hologram again after being reflected, the present invention is not limited to that, and the angle selectivity of the hologram and the incident angle of the ambient light are not limited. Depending on the relationship, the hologram may be diffracted when it first passes through the hologram.

In visualizing the liquid crystal display device in a situation where there is little ambient light, the translucent fluorescent layer 9 which accumulates light when the ambient light is sufficient and has a self-luminous function when the ambient light is little. Display light is obtained by the emitted light.

Examples of the present invention will be described in detail below. <Example 1 = Corresponding to claim 1> A polyester film (Lumirror; manufactured by Toray; thickness of 25 µm) was used as a base material, and Al vapor deposition (thickness of 150 Å) was applied to one surface thereof to form a light reflection layer.
Next, after dissolving acrylic resin (manufactured by Mitsubishi Rayon, Dianal BR resin) in a solvent (MEK: toluene = 1: 1) and mixing 0.1% of a fluorescent whitening agent (manufactured by Nippon Ciba Geigy, Uvitex OB). , 15 μm thick was applied to the Al vapor deposition layer to obtain a fluorescent reflection film.

Next, the argon ion laser (514.5) is recorded by the two-step photographing and recording method as described above.
nm), a volume phase transmission hologram was exposed and recorded on a silver salt photosensitive material for hologram 8E56 film manufactured by AGFA, and then the hologram was peeled from the transparent glass.

On the other hand, a pressure-sensitive adhesive (HJ9150W manufactured by Nitto Denko) was laminated on the fluorescent reflection film, and the hologram was bonded to this to obtain a hologram reflection plate.

On the hologram of this hologram reflector,
A polarizing plate for TN liquid crystal was attached to obtain a final hologram reflection plate.

The polarizing plate side of the hologram reflection plate is arranged so as to face the liquid crystal panel, and the hologram reflection plate is laminated with an adhesive layer interposed therebetween.
The reflection type liquid crystal display device having the structure shown in FIG. 2 was used.

<Example 2 = corresponding to claim 1> Al vapor deposition (150 Å thickness) was applied to one surface of the substrate in the same manner as in Example 1,
A light reflection layer was formed. Next, a phosphorescent pigment (GSS manufactured by Nemoto Special Chemical Co., Ltd.) and Clear were mixed at a weight ratio of 1: 1 to form a phosphorescent coating, which was applied to the Al vapor deposition layer in a thickness of 50 μm to obtain a luminescent fluorescent reflection film. Holograms that were captured and recorded in the same manner as in Example 1 were bonded together to form a hologram reflector.

The hologram reflection plate and the polarizing plate for TN liquid crystal were laminated via an adhesive layer to obtain a reflection type liquid crystal display device having the structure shown in FIG.

<Example 3 = corresponding to claim 2> Al vapor deposition (150Å thickness) was applied to one surface of the substrate in the same manner as in Example 1,
A light reflection layer was formed. Next, a hologram photographed and recorded in the same manner as in Example 1 was bonded onto the Al vapor deposition layer to form a hologram reflection plate (fluorescent layer).

On the other hand, a translucent fluorescent material containing a fluorescent whitening agent is applied and formed in a thickness of 15 μm on one surface of the polarizing plate for TN liquid crystal,
It was used as a fluorescent polarizing plate.

A hologram reflection plate containing no phosphorescent substance (fluorescent material) and the above-mentioned fluorescent polarizing plate are arranged so that the hologram layer and the translucent fluorescent layer face each other, and they are laminated via an adhesive layer. The reflective liquid crystal display device having the structure shown in FIG.

<Example 4 = corresponding to claim 2> Al vapor deposition (150Å thickness) was applied to one surface of the substrate in the same manner as in Example 1,
A light reflection layer was formed. Next, the hologram imaged and recorded in the same manner as in Example 1 was attached onto the Al vapor deposition layer to form a hologram reflection plate.

On the other hand, a phosphorescent paint having a thickness of 50 μm was applied and formed on one surface of a polarizing plate for TN liquid crystal to obtain a polarizing plate containing a phosphorescent substance (fluorescent material).

The hologram reflection plate containing no phosphorescent material (fluorescent material) and the above-mentioned fluorescent polarizing plate are arranged so that the hologram layer and the translucent fluorescent layer face each other, and are laminated via an adhesive layer, The reflective liquid crystal display device having the structure shown in FIG. 3 was used.

<Example 5 = corresponding to claim 3> As in Example 1, Al vapor deposition (thickness 150 Å) was applied to one surface of the substrate,
A light reflection layer was formed.

A holographic recording light-sensitive material was prepared by adding 0.1% of a fluorescent whitening agent (Ubitex OB manufactured by Ciba-Geigy Japan) to the light-sensitive material described in Example 1 of JP-A-7-261640. Next, a hologram photographed and recorded in the same manner as in Example 1 was attached onto the Al vapor deposition layer to form a fluorescence hologram reflection plate.

On the hologram of this hologram reflector,
A polarizing plate for TN liquid crystal was attached to obtain a final hologram reflection plate.

The polarizing plate side of the hologram reflection plate is arranged so as to face the liquid crystal panel, and the hologram reflection plate is laminated via an adhesive layer,
A reflection type liquid crystal display device having the structure shown in FIG. 4 was used.

<Example 6 = Corresponding to claim 4> An ink prepared by mixing an Al paste and a fluorescent material containing an optical brightening agent is applied and formed on one surface of the same substrate as in Example 1,
It was used as a fluorescent light reflection layer.

Next, a hologram photographed and recorded in the same manner as in Example 1 was bonded onto the fluorescent light reflection layer to form a hologram reflection plate.

On the hologram of this hologram reflector,
A polarizing plate for TN liquid crystal was attached to obtain a final hologram reflection plate.

The hologram reflector is arranged so that the polarizing plate side faces the liquid crystal panel, and is laminated via an adhesive layer,
A reflection type liquid crystal display device having the structure shown in FIG. 5 was used.

According to the reflection type liquid crystal display device equipped with the hologram reflection plate according to the above-mentioned embodiment, the display image on the white background excluding the yellowish tint is visible in a situation where the ambient light is sufficient. Further, even in a situation where there is little ambient light, the self-luminous function of the phosphorescent substance (fluorescent material) allows the displayed image to be visually recognized without the need for the built-in light source of the liquid crystal display device. In the above examples, as the fluorescent light reflecting layer, it was only a description regarding the use of the fluorescent brightening agent, but it can be appropriately changed also as a fluorescent light reflecting layer in other fluorescent luminous paint. Needless to say.

[0052]

As described above, since the hologram reflector according to the present invention has a light-storing substance at any place, the built-in light source of the liquid crystal display device can be used even when the ambient light is small such as at night. The displayed image can be visually recognized without requiring. Further, in a situation where the ambient light is sufficient, when the volume phase transmission hologram is used, the display light is less yellowed, and a display closer to white (paper white) is possible.

[0053]

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an outline of a configuration of a reflective liquid crystal display device using a hologram reflector of the present invention.

FIG. 2 is an explanatory diagram showing an example of the configuration of a reflective liquid crystal display device using the hologram reflector of the present invention.

FIG. 3 is an explanatory diagram showing an example of a configuration of a reflective liquid crystal display device using the hologram reflector of the present invention.

FIG. 4 is an explanatory diagram showing an example of the configuration of a reflective liquid crystal display device using the hologram reflector of the present invention.

FIG. 5 is an explanatory diagram showing an example of the configuration of a reflective liquid crystal display device using the hologram reflector of the present invention.

[Explanation of symbols]

A ... Fluorescent reflection film 2 ... Liquid crystal panel 3 ... Polarizing plate 4 ... Polarizing plate 6 ... Volume phase transmission hologram layer 8 ... Light reflection layer 9 ... Translucent fluorescent layer 10 ... Base material

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03H 1/02 G09F 9/00 324 2K009 G09F 9/00 324 336A 5C094 336 9/35 5G435 9/35 G02B 1 / 10 Z F term (reference) 2H042 DA01 DA02 DA11 DB00 DC02 DC04 DE04 2H048 FA04 FA07 FA09 FA15 FA22 2H049 CA05 CA09 CA11 CA28 CA30 2H091 FA08Z FA14Z FA19Z FA43Z FC01 FC18 FD06 LA02 OH01 BB01 EE01 HFF01 FF01 HO01 FF01 FF01 FF01 FF01 FF01 FF01 FF01 FF01 HO01 FF01 EE00 5C094 AA01 AA22 BA43 EB04 ED11 ED20 5G435 AA01 AA16 BB12 BB15 BB16 CC13 GG01 HH06

Claims (11)

[Claims] 1. A hologram reflection plate having a light reflection layer formed on one surface of a volume phase hologram layer, wherein a layer containing a phosphorescent substance is arranged between the hologram layer and the light reflection layer. Characteristic hologram reflector. 2. A hologram reflection plate having a light reflection layer formed on one surface of a volume phase hologram layer, wherein a layer containing a phosphorescent substance is arranged on the surface of the hologram layer on the side where the light reflection layer is not formed. A hologram reflector which is characterized by: 3. A hologram reflection plate having a light reflection layer formed on one surface of a volume phase hologram layer, wherein the hologram layer has a structure in which a phosphorescent substance is dispersed in a photosensitive material. Hologram reflector. 4. A hologram reflection plate having a light reflection layer formed on one surface of a volume phase hologram layer, wherein the light reflection layer is formed by applying an ink in which a light reflection filler and a phosphorescent substance are dispersed. A hologram reflection plate having a formed structure. 5. A film containing a phosphorescent substance is a film having a phosphorescent substance dispersed therein, or an ink having the phosphorescent substance dispersed therein, which is formed by coating on a surface thereof. The hologram reflection plate according to any one of claims. 6. The hologram reflection plate according to claim 1, wherein the light storing substance is a fluorescent substance. 7. The hologram reflection plate according to claim 1, wherein the volume phase hologram layer is a volume phase transmission hologram. 8. The hologram reflection plate according to claim 1, wherein the volume phase hologram layer is a volume phase reflection hologram. 9. The hologram reflection plate according to claim 8, wherein the fluorescent substance is a fluorescent whitening agent that strongly emits light in the visible to blue wavelength range. 10. The hologram reflection plate according to claim 1, wherein a polarizing film is further laminated on the outermost surface of the hologram layer on the side where the light reflection layer is not formed. 11. A hologram reflection plate according to claim 10 is arranged on the back side (opposite to the observer) of a liquid crystal panel defining a display pattern so that the polarizing film faces the liquid crystal panel. A liquid crystal display device.