JP2002341326A - Reflection liquid crystal display device and manufacturing method for optical path polarizing plate used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection liquid crystal display device wherein light intensity and visibility of image light are enhanced by effectively utilizing external light (incident light) and bright and quality image display can be performed. SOLUTION: The reflection type liquid crystal display device 10 is provided with a pair of glass substrates 11 and 12 disposed opposite to each other, a liquid crystal layer 13 interposed between the glass substrates 11 and 12 and a reflection plate 14 for reflecting external light made incident from the glass substrate 12 on the observer side to the glass substrate 11 on the rear side. A first resin layer 26 of a light path polarizing plate 25 has a plurality of triangular prism relieves 17 each having an inclined face 17a inclined to the substrate horizontal face of the glass substrate 11 on the rear side. The angle of the reflected light reflected by the glass substrate 12 on the observer side and the angle of the image light reflected by the reflection plate 14 and emitted to the external part are made different from each other by changing the advancing direction of the external light made incident from glass substrate 12 on the observer side to the glass substrate 11 on the rear side and the advancing direction of the external light reflected by the reflection plate 14 (cf. reflected light R1 and R2 ).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a liquid crystal display device, and more particularly to a reflection type liquid crystal display device for displaying an image using reflected light of external light and a method of manufacturing an optical path deflecting plate used in the liquid crystal display device.

[0002]

2. Description of the Related Art In recent years, liquid crystal displays (LCDs (Liquid C
rystal Display)) is widely used as a display unit of a notebook personal computer or the like. In recent years,
Liquid crystal display devices are also rapidly increasing in size, and are expected to replace CRTs (Cathode Ray Tubes), which are generally used as display units for desktop personal computers and the like.

[0003] Such a liquid crystal display device generally employs a transmissive system in which a light source called a backlight is arranged on the back surface of a liquid crystal cell and light transmitted from the backlight is viewed by an observer. However, the power consumption of the backlight is very large, which is the main cause of shortening the battery life of a notebook personal computer and the like, and the thickness and weight of the liquid crystal display device are increased by the amount of the backlight.
For this reason, a reflection type liquid crystal display device is generally used as a display unit of a small calculator, a mobile phone, or the like in which battery life or portability is a problem.

[0004] The reflection type liquid crystal display device is used for displaying an image by reflecting external light incident from the observer side by a reflection plate disposed on the back surface of the liquid crystal layer. It has the advantages that it can be driven by a battery with electric power, is thin and lightweight, and generates a small amount of heat.

FIG. 4 shows an example of a conventional reflection type liquid crystal display device. As shown in FIG. 4, a conventional reflection type liquid crystal display device 20 includes a pair of glass substrates 21 and 22 arranged opposite to each other, a liquid crystal layer 23 sandwiched between the glass substrates 21 and 22, and a back side. And a reflector 24 provided on the surface side of the glass substrate 21 adjacent to the liquid crystal layer 23. Here, external light incident from the observer side is reflected by the reflector 2 via the glass substrate 22 and the liquid crystal layer 23 on the observer side.
4 is reflected by the reflection plate 24 and used for image display.

In the reflective liquid crystal display device 20, due to its structure, the angle of the reflected light R1 reflected by the glass substrate 22 on the observer side is equal to the angle of the reflected light R2 reflected by the reflector 24. Therefore, when viewed from the observer side, the reflected lights R1 and R2 overlap and the display screen tends to be difficult to see. For this reason, in the reflection type liquid crystal display device 20, in general, a diffusion function is given to the reflection plate 24, or a forward scattering layer is provided on the observer side surface of the observer side substrate, so that the reflection light R1, R2 is reduced. Prevents overlap.

[0007]

However, if a diffusing function is provided by the reflection plate 24 or the forward scattering layer, external light scattered by the reflection plate 24 or the forward scattering layer is used as image light. There is a problem that the intensity is weakened and the brightness of the display screen cannot be sufficiently secured.

In recent years, with the development and spread of portable information processing apparatuses such as portable telephones and portable information terminals having a large amount of information, there has been a demand for a reflective liquid crystal display apparatus capable of displaying high-quality and full-color images. There is a strong demand for ensuring sufficient brightness of the display screen of the display device.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing points, and improves the light intensity and visibility of image light by effectively using external light (incident light) to obtain a bright and high-quality image. It is an object of the present invention to provide a reflective liquid crystal display device capable of performing display and a method of manufacturing an optical path deflecting plate used in the device.

[0010]

According to a first aspect of the present invention, a pair of substrates disposed opposite to each other, a liquid crystal layer sandwiched between the pair of substrates, and a pair of the substrates are provided. A reflector that reflects external light incident from the observer-side substrate toward the rear substrate; and a traveling direction of the external light incident from the observer-side substrate toward the rear substrate and the reflector. By changing the traveling direction of the external light reflected by the optical path deflection, the angle of the reflected light reflected by the observer side substrate and the angle of the image light reflected by the reflector and emitted to the outside are made different. And a reflection type liquid crystal display device comprising:

In the first solution, the optical path deflecting plate has a resin layer having a refractive index different from that of another adjacent layer. It is preferable that a plurality of interfaces inclined with respect to the horizontal plane of the rear-side substrate are formed therebetween. Preferably, the resin layer is a color filter layer. The optical path deflector has at least two resin layers having different refractive indices stacked on each other, and between these resin layers, a plurality of interfaces inclined with respect to the horizontal plane of the rear-side substrate are provided. Preferably, it is formed. Preferably, the difference between the refractive indices of the two resin layers is substantially constant irrespective of the wavelength. It is preferable that at least one of the two resin layers is a color filter layer. Further, it is preferable that the optical path deflecting plate is provided on a surface of the observer side substrate adjacent to the liquid crystal layer. Furthermore, it is preferable that each interface has a different inclination angle depending on a position in a display screen.

According to a second aspect of the present invention, there is provided an optical path deflecting plate for changing a traveling direction of external light incident from a viewer-side substrate toward a back-side substrate among a pair of substrates sandwiching a liquid crystal layer. In the manufacturing method, a step of preparing a molding die having a plurality of triangular prism-shaped concave portions, and a step of molding a resin using the molding die to form a resin plate having a plurality of triangular prism-shaped projections. A method for manufacturing an optical path deflector is provided.

It is preferable that the above-mentioned second solution further includes a step of forming a resin layer on the surface of the plurality of triangular prism-shaped protrusions on the resin plate.

According to the present invention, the external light (image light) reflected by the reflection plate is emitted at an angle different from the angle of the reflected light reflected by the observer-side substrate. It is possible to prevent the reflected lights from overlapping each other without lowering the light intensity, improve the light intensity and visibility of the image light in a specific viewing direction, and perform bright and high-quality image display.

Further, according to the present invention, an optical path deflecting plate is provided on the surface side of the observer side substrate adjacent to the liquid crystal layer, and a color filter layer is constituted by a resin layer included in the optical path deflecting plate. Problems such as blurring of an image, reduction in contrast, and color blur can be effectively prevented. Furthermore, by making the inclination angle of each interface of the resin layer included in the optical path deflection plate different according to the position in the display screen, the external light (image light) reflected by the reflection plate can be viewed at a specific visual height or visual height. You can make it easier to focus on points,
Even in the case of a liquid crystal display device having a large display screen, visibility can be increased over the entire display screen.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing one embodiment of a reflection type liquid crystal display device according to the present invention.

As shown in FIG. 1, a reflection type liquid crystal display device 1
0 is a pair of glass substrates 1 arranged opposite to each other.
1, 12, a liquid crystal layer 13 sandwiched between glass substrates 11, 12, and an observer-side glass substrate (observer-side substrate) 12
And a reflecting plate 14 for reflecting external light incident from the front side toward the glass substrate (rear substrate) 11 on the rear side. An optical path deflecting plate 25 is provided on the surface side of the glass substrate 12 on the observer side adjacent to the liquid crystal layer 13. The reflecting plate 14 is provided on the front side of the rear glass substrate 11 which is not adjacent to the liquid crystal layer 13 as shown in FIG. It may be provided on the side. The reflection plate 1
When the substrate 4 is provided on the front surface of the rear glass substrate 11 adjacent to the liquid crystal layer 13, the electrode 4 may also serve as an electrode of the rear glass substrate 11. On the front surface of the glass substrate 12 on the observer side, the phase difference plate 15 and the polarizing plate 1 are provided.
6 are stacked. Here, external light incident from the observer side is applied to the reflector 14 via the polarizing plate 16, the phase difference plate 15, the glass substrate 12, the optical path deflecting plate 25 and the liquid crystal layer 13 on the observer side, and The light is reflected at 14 and used for image display.

Here, the optical path deflecting plate 25 is composed of a first resin layer 26 and a second resin layer 2 having different refractive indices stacked on each other.
7, a plurality of interfaces are formed between the resin layers 26 and 27 and are inclined with respect to the horizontal plane of the rear glass substrate 11. That is, the first resin layer 26
The glass substrate 11 on the back side has a plurality (many) of triangular prism reliefs (triangular prism-shaped projections) 17 each having an inclined surface 17 a inclined with respect to the horizontal plane of the substrate.
As a result, a saw-toothed interface is formed between the first resin layer 27 and the second resin layer 27. And, by such an optical path deflecting plate 25,
From the glass substrate 12 on the observer side to the glass substrate 11 on the back side
The traveling direction of the external light incident toward the light source and the traveling direction of the external light reflected by the reflector 14 are changed, and the angle of the reflected light reflected by the glass substrate 12 on the observer side and the reflected light by the reflector 14 are changed. The angle of the image light emitted to the outside is different from that of the image light (see the reflected lights R1 and R2 in FIG. 1).

The first resin layer 26 is formed on the glass substrate 1
When the refractive index of the first resin layer 12 or the second resin layer 27 is set to about 1.5, a material having a refractive index different from the refractive index of the second resin layer 27 in the range of 1.3 to 1.7 is used. Is preferred.
Specifically, for example, as a low refractive index resin having a refractive index of 1.5 or less, a fluorine resin, a silicon resin, or the like can be used. In addition, as a high refractive index resin having a refractive index of 1.5 or more, epoxy resin, acrylic resin, polyester resin,
An amino resin, a polyurethane resin, or the like can be used. The second resin layer 27 has a refractive index of about 1.5,
As a material, an acrylic resin or an epoxy resin can be used. The second resin layer 27 can be a colorless protective layer or a color filter layer of three colors of R (red), G (green), and B (blue). Also, the first
It is preferable that the difference between the refractive indices of the resin layer 26 and the second resin layer 27 be substantially constant regardless of the wavelength.

The triangular prism relief 1 of the first resin layer 26
As the shape of 7, the length of the side facing the glass substrate 11 on the observer side of the triangular cross section is preferably about 10 μm (see FIG. 3). Further, the inclination angle of the inclined surface 17a is an arbitrary angle of 1 degree to 44 degrees with respect to the horizontal plane of the rear glass substrate 11 (preferably 5 degrees to 35 degrees,
More preferably, it is 10 degrees to 30 degrees).
In addition, the inclination angle of each inclined surface 17a can be arbitrarily designed according to the use condition of the reflection type liquid crystal display device 10 (that is, the position of the light source and the observer). In addition, each inclined surface 17
In “a”, the inclination angle may be different depending on the position in the display screen. Specifically, when the display screen is relatively large, it is preferable to make the inclination angle of each inclined surface 17a different depending on the upper and lower positions in the display screen. In addition to the flat surface of each inclined surface 17a, a large number of irregularly arranged irregularities for scattering light may be formed on the surface by a sand blaster method or the like to impart a diffusion function.

Next, a method of manufacturing the reflection type liquid crystal display device 10 having such a configuration will be described.

First, a mold having a plurality of triangular prism-shaped concave portions corresponding to the triangular prism reliefs 17 of the first resin layer 26 of the optical path deflecting plate 25 is prepared. The concave portion of the mold is formed by ultra-precision processing by ion beam etching.

Next, after a thick film of acrylic resin or the like is printed on the glass substrate 12, the acrylic resin or the like is cured while being pressed by a prepared mold, and a resin plate having triangular prism-shaped protrusions is formed on the glass substrate. To form Note that the triangular prism-shaped projections are formed continuously so that their axes are aligned in parallel. Also, if necessary, to provide a diffusion function,
A large number of randomly arranged irregularities that scatter light are formed on the surface by a sandblaster method or the like.

Then, a resin layer (color filter layer) is formed on the surface of the plurality of triangular prism-shaped protrusions on the resin plate by spin coating or the like. Further, if necessary, a protective film is formed on the resin layer (color filter layer). This allows
The glass substrate 12 with the optical path deflecting plate 25 is formed.

After that, after an orientation film (not shown) is applied on the glass substrate 11 serving as the opposite substrate, a rubbing process is performed in a direction orthogonal to the alignment of the liquid crystal by the orientation of the glass substrate 12. In addition, ITO sputtering is performed to form an electrode on such an alignment film.

Then, after the gap material is sprayed on the glass substrate 11 or the glass substrate 12, the glass substrates 11, 12 are interposed via spacers or the like in a state in which a portion other than the sealing port for sealing the liquid crystal is sealed with a sealing material or the like. To form an empty cell (a cell in which liquid crystal is not sealed) having a predetermined gap thickness (for example, 5.0 μm).

Thereafter, a liquid crystal material such as a TN type liquid crystal is sealed in the empty cell, and a liquid crystal layer 13 is formed. Note that a normal vacuum sealing method can be used as a method for sealing the liquid crystal material. Specifically, for example, after placing an empty cell in a perjar and keeping the temperature at about 50 ° C., the inside of the perjar is evacuated to a degree of vacuum of about 0.5 mmHg, and a liquid crystal material is dropped into a sealing opening of the empty cell to drop the empty cell. Cover the sealing opening. Then, by gradually returning the degree of vacuum in the pell jar to atmospheric pressure, the empty cell is filled with liquid crystal material, and finally the sealing opening of the liquid crystal material is sealed with ultraviolet curing resin and cured by irradiating ultraviolet rays. Let it.

The liquid crystal cell (liquid crystal display element) thus manufactured is provided on its surface with various functional layers (a retardation plate 15).
And a polarizing plate 16, a color filter, etc.), and finally, the reflection type liquid crystal display device 1 as shown in FIG.
0 is produced.

As described above, according to the present embodiment, the optical path deflecting plate 25 is used to control the direction in which external light is incident from the glass substrate 12 on the observer side toward the glass substrate 11 on the back side and the reflection plate 14. Since the traveling direction of the reflected external light is changed, the external light (image light) reflected by the reflector 14 is emitted at an angle different from the angle of the reflected light reflected by the glass substrate 12 on the observer side. Becomes For this reason, the reflected light R1, R2 can be obtained without lowering the light intensity of the external light (image light).
It is possible to prevent overlap between them, improve the light intensity and visibility of image light in a specific viewing direction, and perform bright and high-quality image display.

According to the present embodiment, the optical path deflecting plate 25 is provided on the surface side of the glass substrate 12 on the observer side adjacent to the liquid crystal layer 13, and the second resin layer included in the optical path deflecting plate 25 is provided. By forming the color filter layer by using 27, it is possible to effectively prevent problems such as blurring of an image, reduction in contrast, and color bleeding.

Further, according to the present embodiment, the first resin layer 2 forming the interface between the resin layers 26 and 27 of the optical path deflecting plate 25 is formed.
6 so that the perpendicular of each inclined surface 17a of the triangular prism relief 17 of FIG. 6 is inclined toward the upper side of the display screen when viewed from the observer side.
Since 7a is inclined with respect to the horizontal plane of the glass substrate 11 on the rear side, in a normal use mode where external light is incident from above the display screen, external light (image light) reflected by the reflector 14 is It is easy to concentrate on the viewing position of the observer, and the visibility can be further increased.

Furthermore, according to the present embodiment, the inclination angle of each inclined surface 17a of the triangular prism relief 17 of the first resin layer 26, which forms the interface between the resin layers 26 and 27 of the optical path deflecting plate 25, is displayed on the display screen. (Upper and lower positions), the external light (image light) reflected by the reflector 14 can be easily concentrated at a specific viewing height, and a liquid crystal having a large display screen Even in the case of a display device, the visibility can be improved over the entire vertical area of the display screen.

It is to be noted that not only the inclination angle of each inclined surface 17a of the first resin layer 26 of the optical path deflecting plate 25 is made different depending on the vertical position in the display screen, but also the inclination angle of each inclined surface 17a is displayed on the display screen. May be made different depending on the vertical and horizontal positions in the inside. Accordingly, it is possible to easily concentrate the external light (image light) reflected by the reflection plate 14 on a specific viewing point, and even in the case of a liquid crystal display device having a large display screen, The visibility can be increased over the entire area in the direction and the left-right direction.

In the above-described embodiment, a glass substrate has been described as an example of the substrates 11 and 12 used in the reflection type liquid crystal display device 10. However, the present invention is not limited to this.
Any substrate such as a plastic substrate can be used.

Further, in the above-described embodiment,
The function of a color filter is provided to the second resin layer 27 of the optical path deflecting plate 25. However, the present invention is not limited to this. For example, a color filter may be provided on the surface of a finally manufactured liquid crystal cell (liquid crystal display element). A glass substrate 11 as a rear substrate
It may be provided on the side.

Further, in the above-described embodiment, the optical path deflecting plate 25 has a two-layer structure of the first resin layer 26 and the second resin layer 27. However, the optical path deflecting plate 25 has a single-layer structure of only the first resin layer 26. An inclined interface may be formed between the first resin layer 26 and another adjacent layer (such as the glass substrate 12 and the liquid crystal layer 13). In this case, the first
It is preferable that the resin layer 26 be a color filter layer.

[0037]

Next, a specific example of the above-described embodiment will be described.

In this embodiment, a 10-inch reflective liquid crystal display device 10 manufactured according to the above-described method will be described.
The visibility was confirmed. In this embodiment, as shown in FIG. 3, as the first resin layer 26 of the optical path deflecting plate 25, a fluorine-based acrylic resin having a refractive index of 1.4 is used, and a large number of triangular prisms extending in the left-right direction of the display screen. A relief 17 was formed. Here, the length of the side of the triangular cross section of each triangular prism relief 17 facing the glass substrate 12 on the observer side is 10 μm.
m. Also, the inclined surface 17a of each triangular prism relief 17
The inclination angle theta ₂ 5 degrees, 15 degrees, and 20 degrees. Each inclined surface 17a was inclined with respect to the horizontal plane of the glass substrate 11 on the back side such that the perpendicular line was inclined toward the upper side of the display screen when viewed from the observer side. On the other hand, the second
As the resin layer 27, a resin layer mainly composed of an acrylic resin having a refractive index of 1.5 (Example 1), or a resin layer having a refractive index of 1.5
(Example 2) was used.

Then, as shown in FIG.
Angle θ of external light with respect to the horizontal plane of the display device 10₁Is 30
, 45 °, 60 °
Visual observation of the reflective liquid crystal display device 10 according to the first and second embodiments.
Was confirmed. Note that the incident angle θ of the external light₁, Triangular prism lily
Angle of inclination 17₂, And the radiation angle θ of external light (image light)
₃Is as shown in Table 1.

[0040]

[Table 1]

As a result of confirming the visibility of the reflective liquid crystal display devices 10 according to Examples 1 and 2 for all the combinations shown in Table 1, the reflective liquid crystals according to Examples 1 and 2 were confirmed. Both the light intensity and the visibility of the display device 10 were extremely good as compared with the conventional reflection type liquid crystal display device, and a bright and high quality image could be obtained. Further, there was no difference in visibility depending on the position in the display screen.

[0042]

As described above, according to the present invention, it is possible to improve the light intensity and visibility of image light by effectively utilizing external light (incident light), and to perform bright and high-quality image display. Can be.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a reflection type liquid crystal display device according to the present invention.

FIG. 2 is a view for explaining a specific embodiment of the reflection type liquid crystal display device shown in FIG. 1;

FIG. 3 is a diagram showing details of an optical path deflecting plate of the reflection type liquid crystal display device shown in FIG. 2;

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

[Explanation of symbols]

 Reference Signs List 10 reflective liquid crystal display device 11 glass substrate on the back side (back side substrate) 12 glass substrate on the observer side (substrate on the observer side) 13 liquid crystal layer 14 reflector 15 retarder 16 polarizing plate 17 triangular prism relief (triangular prism-shaped Projection 17a Inclined surface (interface) 18 Light source 25 Optical path deflector 26 First resin layer 27 Second resin layer

Claims (10)

[Claims] 1. A pair of substrates arranged to face each other, a liquid crystal layer sandwiched between the pair of substrates, and light incident from an observer-side substrate to a back-side substrate of the pair of substrates. A reflecting plate that reflects external light; and changing the traveling direction of external light incident from the observer-side substrate toward the rear-side substrate and the traveling direction of external light reflected by the reflecting plate to perform the observation. A reflection type liquid crystal display device comprising: an optical path deflecting plate that makes an angle of reflected light reflected by a user side substrate different from an angle of image light reflected by the reflector and emitted to the outside. 2. The optical path deflecting plate has a resin layer having a refractive index different from the refractive index of another adjacent layer, and between the resin layer and the other layer, there is provided a back surface substrate. 2. The reflective liquid crystal display device according to claim 1, wherein a plurality of interfaces inclined with respect to the horizontal plane of the substrate are formed. 3. The reflection type liquid crystal display device according to claim 2, wherein said resin layer is a color filter layer. 4. The optical path deflecting plate has at least two resin layers having different refractive indexes stacked on each other, and a plurality of resin layers inclined with respect to a horizontal plane of the rear substrate between the resin layers. 2. The reflection type liquid crystal display device according to claim 1, wherein an interface is formed. 5. The reflective liquid crystal display device according to claim 4, wherein the difference between the refractive indices of said two resin layers is substantially constant irrespective of wavelength. 6. A color filter layer according to claim 4, wherein at least one of said two resin layers is a color filter layer.
The reflective liquid crystal display device as described in the above. 7. The reflective liquid crystal display according to claim 1, wherein said optical path deflector is provided on a surface side of said observer side substrate adjacent to said liquid crystal layer. apparatus. 8. The reflection type liquid crystal display device according to claim 2, wherein each of the interfaces has a different inclination angle depending on a position in a display screen. 9. A method for manufacturing an optical path deflecting plate for changing a traveling direction of external light incident from a viewer-side substrate to a back-side substrate of a pair of substrates sandwiching a liquid crystal layer, the method comprising: Preparing a molding die having the following steps: and forming a resin plate using the molding die to form a resin plate having a plurality of triangular prism-shaped projections. . 10. The method of manufacturing an optical path deflecting plate according to claim 10, further comprising a step of forming a resin layer on a surface of said plurality of triangular prism-shaped protrusions on said resin plate.