JP2003344849A - Liquid crystal display element and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display element with which excellent color display is obtainable by making a difference in appearance between color display in a reflective mode and color display in a transmissive mode little. <P>SOLUTION: The liquid crystal display element is constructed by placing a liquid crystal layer between a transparent substrate located on the observer's side and a transparent substrate 1 located on the rear surface side. A first color filter layer 2, a transflective film 3 and a second color filter layer 4 are successively laminated and disposed from the transparent substrate 1 side between the transparent substrate 1 located on the rear surface side and the liquid crystal layer. A surface of the transflective film 3 is roughened. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device capable of color display in both reflective mode and transmissive mode and a method for manufacturing the same.

[0002]

2. Description of the Related Art Generally, a liquid crystal display element that constitutes a liquid crystal display is a non-emission type, and thus requires external irradiation light. As the externally radiated light used in the liquid crystal display, external light such as sunlight or a backlight provided in the liquid crystal display is often used.

In the case of a liquid crystal display for a vehicle, a liquid crystal display for a mobile phone, etc., it is characterized in that there is a large variation in the use environment in relation to the externally radiated light from darkness at night to direct sunlight. The design of a liquid crystal display capable of coping with the fluctuation of the external irradiation light is required.

As a liquid crystal display which is effective for use in the case where there is a large fluctuation in the externally radiated light, a transmissive display system (hereinafter, referred to as a transmissive display system) which utilizes illumination from the back surface of the liquid crystal display element when the use environment is dark. Mode), and when the environment is bright, it reflects the external light and adopts a reflective display system (hereinafter, reflective mode), which is a semi-transmissive function that has both transmissive and reflective functions. One using a reflective liquid crystal display element has been developed, and in recent years, many liquid crystal display elements for color display have also been developed.

Here, the structure of a conventional general transflective color liquid crystal display element will be briefly described.

In the transflective color liquid crystal display element, a transparent substrate located on the front side (front side) which is the observer side and a transparent substrate located on the back side (rear side) which is the observer side are provided. The two transparent substrates are arranged in parallel with each other with a space therebetween, and the outer peripheries thereof are sealed with a sealing material.

A transparent common electrode is disposed on the lower surface of the front transparent substrate so as to be in close contact therewith, and below the transparent common electrode, a liquid crystal is formed according to a voltage applied between the electrodes. An alignment film that controls the alignment of molecules is arranged so as to be in close contact. Further, a polarizing film is provided on the upper surface of the front transparent substrate.

On the other hand, a semi-transmissive reflective film is provided on the upper surface of the rear transparent substrate, and a color filter layer is provided on the upper surface. A transparent segment electrode is arranged on the upper surface of the color filter layer, and an alignment film is arranged so as to be in close contact with the upper surface. Also,
A polarizing film is arranged outside the rear substrate.

A backlight unit having a light source and a light guide plate for emitting the light of the light source toward the liquid crystal display element is disposed on the lower surface of the rear transparent substrate.

A liquid crystal is enclosed in an enclosed space surrounded by the two transparent substrates and a sealing material, and further, in order to keep the space between the front substrate and the rear substrate accurately and accurately, both orientations are set. A plurality of spherical or columnar spacers are interposed between the films.

[0011]

The color display in the color liquid crystal display device having such a configuration is shown in the explanatory view of FIG. 4, and in the reflection mode utilizing the external light incident from the front side, the rear side is used. Since the external light is reflected by the semi-transmissive reflection film 3 provided on the upper surface of the transparent substrate 1, the light passes through the color filter layer 6 twice and is visible to the user. On the other hand, in the transmissive mode that uses the light from the light source arranged below the rear transparent substrate 1, the light passes through the semi-transmissive reflective film 3 and passes through the color filter layer 6 once. , Will be visually recognized by the user.

As described above, when the color display in the reflective mode and the color display in the transmissive mode differ in the number of times the light passes through the color filters, the optical path lengths passing through the color filters differ, so that the appearance of the color display also differs. The problem occurs.

The present invention has been made to solve the above problems.
It was obtained as a result of earnest efforts, and the purpose is to reduce the appearance difference between the color display in the reflective mode and the color display in the transmissive mode, and to obtain a good color display. A liquid crystal display device is provided.

Further, in the liquid crystal display device having the above-mentioned structure, if the surface of the semi-transmissive reflection film is a mirror surface, when the light source is a point light source, the display image cannot be recognized in a direction other than the specular reflection direction, and characters are not recognized. Blurring may occur or the reflectance may decrease. Therefore, in order to provide the liquid crystal display element with a light diffusing function, a liquid crystal display element having a structure in which a diffusion film is provided on the lower surface of the semi-transmissive reflective film has been developed.

The inventors of the present invention have also developed a liquid crystal display element having a structure in which the diffusion film is omitted and the liquid crystal display element has a light diffusing function.

[0016]

In order to achieve the above-mentioned object, a liquid crystal display device according to claim 1 of the present invention has a transparent substrate located on the observer side and a transparent substrate located on the back side. A liquid crystal display element in which a liquid crystal layer is disposed on a transparent substrate and a liquid crystal layer between the transparent substrate and the liquid crystal layer, the first color filter layer, the semi-transmissive reflective film, and the second transparent film. The color filter layers are sequentially stacked and arranged, and the surface of the semi-transmissive reflective film on the side of the transparent substrate located on the observer side is a rough surface.

According to the liquid crystal display element of the present invention, for example,
By making the film thicknesses of the first color filter layer and the second color filter layer approximately the same, it is possible to make the appearance of the color display visually recognized by the user in the reflection mode and the transmission mode substantially the same. Further, the unevenness formed by roughening the surface of the semi-transmissive reflective film makes it possible to maintain the light diffusivity with respect to the reflected light.

A liquid crystal display element according to a second aspect of the present invention is the liquid crystal display element according to the first aspect, wherein the first color filter layer on the transparent substrate side located on the observer side is provided. By forming unevenness on the surface and forming the semi-transmissive reflective film on the surface of the semi-transmissive reflective film to have substantially the same thickness, the surface of the semi-transmissive reflective film on the transparent substrate side located on the observer side is roughened. It is characterized by being

According to the liquid crystal display element of the present invention, the semi-transmission made of metal in which the unevenness formed in advance on the surface of the substrate on which the metal film is disposed is made to have substantially the same film thickness by the vapor deposition method or the sputtering method. It is possible to easily and surely affect the surface of the reflective film.

The liquid crystal display element according to claim 3 is the liquid crystal display element according to claim 2, wherein the filler mixed in the forming agent of the first color filter layer
The liquid crystal display element according to claim 4, wherein the surface of the first color filter layer is provided with irregularities.
The filler has a particle size larger than the film thickness of the first color filter layer.

According to the liquid crystal display device of these inventions, it is possible to easily and reliably form the unevenness on the front surface of the first color filter layer.

The liquid crystal display device according to claim 5
The manufacturing method is one of the two transparent substrates that sandwich the liquid crystal layer.
Between the transparent substrate located on the back side and the liquid crystal layer, this
From the transparent substrate side, the first color filter layer, semi-transmissive reflection
The film and the second color filter layer are sequentially stacked and arranged.
Of the semi-transmissive reflective film on the transparent substrate side on the observer side
Liquid crystal display device having a structure in which light diffusivity is imparted to the surface
And a first color mixture containing a filler.
Using a filter layer forming agent, a transparent substrate located on the viewer side
The first color filter having unevenness on the plate-side surface
A layer is formed, and a semi-transmissive reflective film with a substantially uniform thickness is formed on the upper surface of the layer.
By stacking the forming materials, it is transparent on the viewer side.
Form a semi-transmissive reflective film with unevenness on the surface that will be the substrate side
It is characterized by

According to the method of manufacturing a liquid crystal display element of the present invention, the uneven shape formed on the surface of the semi-transmissive reflective film can be easily and reliably adjusted by the mixing amount of the filler and the particle size of the filler. it can.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION A liquid crystal display device of the present invention and a method for manufacturing the same will be described below. The description of the same components as those of the conventional color liquid crystal display element will be omitted.

FIG. 1 shows a first example of a liquid crystal display device according to the present invention.
It is explanatory drawing which shows the principal part in embodiment, and respond | corresponds to FIG. 4 explaining the conventional structure.

The liquid crystal display device according to the present embodiment is arranged between the transparent substrate 1 located on the rear side and the liquid crystal layer (not shown) among the two transparent substrates made of glass or the like which sandwich the liquid crystal layer. The first color filter layer 2, the semi-transmissive reflective film 3, and the second color filter layer 4 having substantially the same thickness as the first color filter layer 2 are sequentially stacked from the rear side.

In the color display in the color liquid crystal display device having such a structure, in the reflection mode utilizing the external light incident from the front side, the semi-transmissive reflection film 3 provided on the upper surface of the transparent substrate 1 on the rear side. Since the outside light is reflected by, the light passes through the second color filter layer 4 twice,
It is visible to the user.

In the transmissive mode utilizing light from a light source arranged on the lower surface of the rear substrate, the light passes through the first color filter layer 2, then through the semi-transmissive reflective film 3, and further, It passes through the second color filter layer 4 and is visually recognized by the user.

As described above, in this embodiment, since the first color filter layer 2 and the second color filter layer 4 are formed to have substantially the same thickness, the thickness of these color filters is d. The optical path in both the reflection mode and the transmission mode is about 2d.

In the color liquid crystal display device having such a structure, the optical path lengths in the reflective mode and the transmissive mode can be made substantially the same, so that the color display visually perceived by the user is also substantially the same in appearance. Can be
It has good visibility.

In the present embodiment, the first color filter layer and the second color filter layer are formed to have substantially the same thickness to adjust the color to be visually recognized by the user. Even when the film thicknesses of the first color filter layer and the second color filter layer are different from each other, the first color filter layer and the second color filter layer can be formed by darkening the color of the filter layer formed to be thin. By adjusting the color of the filter layer, the color visually recognized by the user can be made substantially equal.

As shown in FIG. 2, the liquid crystal display element according to this embodiment has a structure in which the semi-transmissive reflective film 3 is provided with light diffusivity.

That is, in the color liquid crystal display element of this embodiment, the surface of the semi-transmissive reflective film 3 on the front side, that is, the interface with the second color filter layer 4 is a rough surface. The unevenness is formed by roughening the surface of the reflective film 3 so that the reflected light has a light diffusing property.

More specifically, the semi-transmissive reflective film 3 is generally formed by depositing a metal film of Al, Ag or the like by a vapor deposition method or a sputtering method. It is difficult to roughen the surface of the semi-transmissive reflective film 3 in advance when forming the film by the vapor deposition method or the sputtering method, and the surface of the formed metal film is roughened in a later step. However, even if the metal film is a thin film, there are technical difficulties. From this point of view, a method is used in which the surface on the side of the substrate on which the metal film is provided is formed in advance in an uneven shape, and the metal semi-transmissive reflection film 3 is formed on this uneven surface by vapor deposition or sputtering. It is easier and more efficient to do. Therefore, in this embodiment, as shown in FIG.
As shown in, the surface of the first color filter layer 2 on which the semi-transmissive reflective film 3 is laminated is roughened to have an uneven shape.

FIG. 3 is an explanatory view showing a concrete example in which the surface of the first color filter layer 2 is formed in an uneven shape. In this embodiment, the unevenness is formed in the surface of the first color filter layer 2. As a method, this first color filter layer 2
The filler 5 having a particle size larger than the film thickness of the first color filter layer 2 is mixed into the forming agent forming the film, and the forming agent of the first color filter layer 2 is spin-coated on the substrate. In this case, a method is used in which the upper part of the filler 5 is projected on the surface of the first color filter layer 2 to spread the unevenness on the surface of the first color filter layer 2.

Then, the semi-transmissive reflective film 3 made of metal is formed on the roughened first color filter layer 2 having irregularities formed on its surface, and the second color filter layer 4 is further formed thereon. To do.

In the first color filter layer 2 and the second color filter layer 4, one pixel forming a color image is composed of a color filter of one dot of red R, green G and blue B. .

If the method of using the filler 5 is adopted as the method of roughening the surface of the first color filter layer 2,
The concavo-convex shape can be easily and reliably adjusted by the mixing amount of the filler 5 and the particle size of the filler 5.

The roughened surface of the semi-transmissive reflective film has a ten-point average roughness (RzD) of 0.5 to 5 μm, an uneven pitch (Sm) of 5 to 30 μm, and a haze value of 20 to 50. It is desirable that the range is set. Further, the filler 5 is
It is also possible to use the one containing the pigment of the color filter in which the filler 5 is mixed.

As a method of roughening the surface of the first color filter layer 2, in addition to the method of using the above-mentioned filler 5, after the first color filter layer 2 is formed, irregularities are formed on the surface by sandblasting. Method or as a material for the first color filter layer 2, an acrylic resin or the like having heat shrinkability is used. After forming the first color filter layer 2 with this material, the first color filter layer 2 is heated to form wrinkles in the first color filter layer 2. A method of forming irregularities on the surface of the surface by generation can be exemplified.

Next, a concrete example will be shown.

In the present embodiment, the particle size of 3 μm is contained in the forming agent of the first color filter layer 2 made of the photosensitive resin of each color in which the pigments of red R, green G and blue B are dispersed.
15wt of plastic beads as the filler 5 of m
% Mixed. By spin-coating this mixed solution to a film thickness of 2 μm, patterning is performed in a predetermined pattern for each color of red R, green G, and blue B, and the first color filter having irregularities due to the filler 5 on the surface thereof. Layer 2 was formed.

Thereafter, a silver reflection film having a thickness of 5 nm is formed on the upper surface of the first color film layer 2 by a sputtering method,
The transflective film 3 was formed.

When the roughened shape of the surface of the substrate (semi-transmissive reflective film) at this time is measured, RzD = 1.5 μm, Sm =
It was 15 μm and the haze value was 35.

Then, the second color filter layer 4 is formed at a position corresponding to the first color filter layer 2 of each color so that the thickness thereof is the same as that of the first color filter layer 2 of 2 μm. . As the forming agent for the second color filter layer 4, the same forming agent as for the first color filter layer 2 was used, but it goes without saying that the filler 5 was not mixed.

In the reflection mode, the color liquid crystal display device having such a structure reflects the outside light by the semi-transmissive reflection film, so that the light passes through the second color filter layer 4 twice and is used. Visible to people.

In the transmission mode using light from a light source arranged on the lower surface of the rear substrate, the light passes through the first color filter layer 2 and then through the semi-transmissive reflective film, and further, It passes through the second color filter layer 4 and is visually recognized by the user. In the present embodiment, the first color filter layer 2 and the second color filter layer 4 are formed to have substantially the same thickness. Therefore, if the thickness of these color filters is d, even in the reflection mode. Also in the transmission mode, the optical path lengths thereof are substantially equal to each other, which is about 2d.

When the color liquid crystal display element having such a structure is incorporated in a liquid crystal display device, there is no difference in chromaticity at the time of display in both the reflection mode and the transmission mode, and the appearance is substantially the same. You can get it.

Further, in the color liquid crystal display element having such a structure, since light diffusivity can be obtained on the surface of the semi-transmissive reflective film on which irregularities are formed, a diffusion layer is formed like a conventional liquid crystal display element. Since it is not necessary to form another resin in another step, the cost can be reduced.

When the filler 5 is not colored as desired and colorless and transparent plastic beads are used, as long as the filler is disposed, the color of the filler is different between the transmission mode and the reflection mode. It will be different. However, as a whole, since the area of the portion where the filler 5 is not provided is larger than the area of the portion where the filler 5 is provided, as a color to be visually recognized by the user,
Compared with the conventional one, there is no significant difference in the visible color tone between the transmission mode and the reflection mode, and the conventional problems can be reduced.

[0051]

As described above, according to the liquid crystal display device of the present invention, there is no difference in chromaticity at the time of display in both transmission modes, and it is possible to obtain a substantially identical appearance. By forming unevenness on the surface of the semi-transmissive reflective film and imparting light diffusivity, it is not necessary to form a diffusion layer in a separate step using a different resin like a conventional liquid crystal display element, It is possible to reduce costs.

Further, in the method for manufacturing a liquid crystal display element of the present invention, the uneven shape formed on the surface of the semi-transmissive reflective film can be easily and reliably adjusted by the mixing amount of the filler and the particle size of the filler. There is an effect such as being able to.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a main part and an optical path length in an embodiment of a liquid crystal display element according to the present invention.

FIG. 2 is an explanatory diagram showing a semi-transmissive reflective film, a first color filter layer and a second color filter layer in an embodiment of a liquid crystal display element according to the present invention.

FIG. 3 is an explanatory diagram showing a specific example in which the surface of the first color filter layer is formed in an uneven shape.

FIG. 4 is an explanatory diagram showing a main part and an optical path length in a conventional liquid crystal display element.

[Explanation of symbols]

1 (rear side) transparent substrate 2 First color filter layer 3 Semi-transmissive reflective film 4 Second color filter layer 5 filler

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshikazu Mori             Hiroshima Opto, 91, Yotsunuki-cho, Miyoshi City, Hiroshima Prefecture             Within the corporation F-term (reference) 2H042 AA26 BA02 BA15 BA20                 2H091 FA02Y FA15Y FA16Y FB06                       FB13 FC02 GA06 GA08 GA16                       LA15 LA16

Claims (5)

[Claims] 1. A liquid crystal display device comprising a liquid crystal layer disposed between a transparent substrate located on the viewer side and a transparent substrate located on the back side, wherein the transparent substrate and the liquid crystal layer located on the back side. The first color filter layer, the semi-transmissive reflective film, and the second color filter layer are sequentially laminated from the transparent substrate side between them, and the semi-transparent substrate positioned on the observer side is the semi-transparent side. A liquid crystal display device, wherein the surface of the transflective film is rough. 2. Observation by forming irregularities on the surface of the first color filter layer on the side of the transparent substrate located on the observer side, and forming the semi-transmissive reflection film on the surface of the irregularities to have substantially the same thickness. The liquid crystal display element according to claim 1, wherein a surface of the semi-transmissive reflective film on the transparent substrate side located on the human side is a rough surface. 3. The liquid crystal display element according to claim 2, wherein unevenness is formed on the surface of the first color filter layer by the filler mixed in the forming agent of the first color filter layer. . 4. The liquid crystal display element according to claim 3, wherein the filler has a particle size larger than a film thickness of the first color filter layer. 5. The first color filter layer and the semi-transmissive reflective film are provided between the transparent substrate located on the back side of the two transparent substrates sandwiching the liquid crystal layer and the liquid crystal layer from the transparent substrate side. A method of manufacturing a liquid crystal display device having a structure in which second color filter layers are sequentially stacked and arranged, and light diffusion is imparted to the surface of the semi-transmissive reflective film on the transparent substrate side located on the observer side. By using a first color filter layer forming agent mixed with a filler, the first color filter layer having irregularities on the surface which is the transparent substrate side located on the observer side is formed, and the upper surface thereof is substantially uniform. Manufacturing of a liquid crystal display device characterized by forming a semi-transmissive reflective film having unevenness on the surface of the transparent substrate side facing the viewer by laminating materials for forming a semi-transmissive reflective film having different thicknesses. Method.