JPH0728055A - Liquid crystal display device and manufacturing method thereof - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a highly reliable reflective liquid crystal display device having a wide viewing angle regardless of the position of a light source, and having a superior display screen in which display defects are unlikely to occur, and a manufacturing method thereof. A scanning-side electrode plate 1 is provided with an electrode composed of two layers of a patterned metal thin film 12 and a transparent thin film 13 arranged on the substrate 11 on the other hand, while the signal-side electrode plate 2 is provided. The transparent electrode 25 and the light scattering layer 24 are provided on the substrate 21 of FIG. Since the light reflected from the metal thin film 12 is scattered by the light scattering layer 24, the viewing angle is increased. Further, since the metal thin film 12 is covered with the transparent thin film 13, its deterioration is prevented and reliability is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflective liquid crystal display device and a method of manufacturing the same, and more particularly to a liquid crystal display having a wide viewing angle regardless of the position of a light source and an excellent display screen with improved screen display reliability. The present invention relates to a device and a manufacturing method thereof.

[0002]

2. Description of the Related Art Generally, a liquid crystal display device is constructed by sandwiching a liquid crystal between two electrode plates having transparent electrodes. The liquid crystal is driven by applying a voltage between the transparent electrodes. The screen is displayed by controlling the plane of polarization of the light that passes through and controlling the transmission / non-transmission by the polarizing film.

In order to obtain a sufficient brightness for displaying on such a liquid crystal display device, a backlight type or light guide type built-in lamp type light source (lamp) is arranged on the side or side of the liquid crystal display device. Type liquid crystal display devices are widely used.

This transmissive liquid crystal display device consumes a large amount of power due to the lamp and has a power consumption that is not much different from other display devices (CRT, PDP, etc.) other than the liquid crystal display device, and is low in power consumption and portable. The original characteristic of the liquid crystal display device that it is possible is impaired.

On the other hand, the reflection type liquid crystal display device uses room light or external light as the transmitted light of the liquid crystal display device, does not have a built-in lamp and is an ideal display device of low power consumption. It is lightweight and convenient to carry.

In such a reflection type liquid crystal display device, the room light and the room light are uniformly distributed on the entire surface of the electrode plate (scanning side electrode plate) on the side opposite to the position of the observer observing the display device. It is usual that a metal thin film that reflects extraneous light is provided, or a reflective film is uniformly provided on the entire surface of another substrate and disposed on the back surface of the substrate. For example, in a color display liquid crystal display, a metal reflective film is provided on the base material of the scanning side electrode plate, and a transparent electrode is provided on the metal reflective film via a color filter layer for coloring transmitted light to perform the scanning. It was used as a side electrode plate.

A method has also been proposed in which a metal reflective film is formed in the same pattern as the above-mentioned electrodes for driving liquid crystal and is used as this liquid crystal driving electrode.

[0008]

However, in the back electrode plate having the metal reflection film uniformly on the entire surface of the substrate of the scanning side electrode plate, the metal reflection film and the transparent electrode are formed through the minute defects of the color filter layer. When the multiple transparent electrodes are electrically connected to the metal reflective film,
There is a problem that when a voltage is applied to one of the electrodes, the other electrode is also driven through the metal reflection film to cause a display defect.

Further, even when a metal reflection film is formed on the back surface of the scanning-side electrode plate, the metal reflection film is easily scratched in the electrode plate manufacturing process or the liquid crystal display device manufacturing process, and the scratch is a display defect. Was the cause of.

When the metal reflection film is formed in the same pattern as the above electrodes for driving the liquid crystal and is used as the electrode for driving the liquid crystal, room light and external light are directly reflected by the patterned metal reflection film. Since the reflected light does not occur at the portion where the metal reflection film does not exist, the reflected light may not be observed depending on the incident angle and the position of the observer, and the display screen may become dark, resulting in a limited viewing angle. Had the problem. Further, when an inexpensive aluminum thin film is used as the metal reflection film, the aluminum is liable to form a hydrate or an oxide to easily cause a display defect, so that it lacks reliability in terms of moisture resistance and the like. .

Furthermore, since the reflection film is provided on the scanning side electrode plate on the side opposite to the observer's position, the screen formed by the liquid crystal appears on the reflection film and appears double. Also had.

The present invention has been made by paying attention to such a problem, and an object of the present invention is that a viewing angle is wide regardless of the position of a light source and a display defect occurs on an excellent display screen. An object is to provide a difficult and highly reliable reflective liquid crystal display device and a manufacturing method thereof.

[0013]

That is, the invention according to claim 1 includes an electrode plate provided with a scanning side electrode for driving liquid crystal, and another electrode plate provided with a signal side electrode. In the liquid crystal display device composed of the liquid crystal sandwiched between the two electrode plates, the scanning-side electrode plate is composed of a patterned metal thin film on the substrate and a transparent thin film arranged to cover the metal thin film. On the other hand, the signal-side electrode plate is provided with two layers of a transparent electrode and a light-scattering layer on the substrate.

In such a liquid crystal display device, incident light such as room light and external light is reflected by the patterned metal thin film, scattered by the light scattering layer of the signal side substrate, and emitted. Therefore, the scattered light can be observed regardless of the position of the incident light source, and the viewing angle is significantly increased.

Further, since the metal thin film is covered with the transparent thin film, the metal thin film is not deteriorated, and therefore display defects are not generated, and the reliability of the liquid crystal display device can be remarkably increased. Become. In addition to this, since the transparent thin film is in contact with the metal thin film, it is possible to significantly reduce the resistance value thereof, and it is also possible to prevent crosstalk between electrodes and improve display uniformity. Become.

Claims 2 and 3 are invented for such technical reasons. That is, the invention according to claim 2 is characterized in that, in the liquid crystal cover device according to claim 1, the metal thin film has the same pattern as the transparent thin film in the effective display region of the liquid crystal display device,
On the other hand, the invention according to claim 2 is the liquid crystal display device according to claim 1, wherein in the effective display area of the liquid crystal display device,
It is characterized in that the metal thin film is composed of a large number of rectangular patterns arranged regularly.

In the invention according to claims 1 to 3, glass, ceramics, plastic films, plastic boards, etc. can be used as the base material of the scanning side electrode plate, and it may be transparent, black, white or other colors. It may be colored. If a black substrate is used, it is possible to improve the contrast of the display screen by forming a black stripe and preventing reflection of a light beam incident on a portion where the metal thin film does not exist. . In particular, when the metal thin film is formed in the same rectangular pattern as the pixel, it is possible to completely prevent the reflected light from the portion other than the pixel. Further, in the case of a semi-transmissive reflection type liquid crystal display device in which a lamp is built in the liquid crystal display device in preparation for use in a dark dark room with little indoor light, a transparent one is preferable.

In the invention according to claims 1 to 3,
As the metal thin film, in addition to a single layer, a multi-layered thin film formed by laminating two or more kinds of metals can be used.
In addition to inexpensive aluminum, a metal thin film having a high visible light reflectance such as silver, aluminum alloy, magnesium, and nickel alloy can be used as the metal constituting the single-layer thin film. It is also possible to laminate a thin film of chromium or the like on the aluminum thin film to improve the adhesion with the transparent thin film.

In the invention according to claims 1 to 3,
As the light-scattering layer, those containing as a main component a transparent resin and a scattering material dispersed in the transparent resin and having a refractive index different from that of the transparent resin can be used. The generated light rays are refracted and reflected at the interface between the transparent resin and the scattering material to change the emission direction thereof. Then, when the fine particle-like scattering material is dispersed in the transparent resin, this refraction and reflection are repeated, so that the light is emitted substantially uniformly in all directions as a whole.

The inventions according to claims 4 to 5 are made based on such a technical background. That is, the invention according to claim 4 is the liquid crystal display device according to any one of claims 1 to 3, wherein the light scattering layer has a transparent resin and a refractive index of the transparent resin dispersed in the transparent resin. A light scattering material having a different refractive index is contained as a main component, and the invention according to claim 5 is the liquid crystal display device according to claim 4, wherein the light scattering material has a diameter of 1 μm.
It is characterized by comprising the following fine particles.

In the invention according to claim 4 or 5, the transparent resin is preferably a resin that withstands heat and the like at the time of manufacturing a liquid crystal display device and has a high visible light transmittance.
Epoxy-based and urethane-based resins can be used, and specifically polymethyl acrylate resin can be used. Further, as will be described later, when the light scattering layer contains a coloring material, it is desirable that patterning can be performed by a photolithography method. As such a resin, an acrylic resin or an epoxy resin having photosensitivity is exemplified. it can.

Further, as the light scattering material, in addition to inorganic fine particles such as titanium oxide, zirconium oxide, lead oxide, aluminum oxide, silicon oxide, magnesium oxide, zinc oxide, barium sulfate, etc., refraction different from the refractive index of the above transparent resin is used. It is possible to specify resin fine particles having a certain ratio.

The polarization plane of the light refracted at the interface between the light scattering material and the transparent resin and transmitted through the light scattering material is rotated to deteriorate the display quality of the liquid crystal display device (the rotation of the polarization plane causes a display). An amorphous material having no birefringence is desirable as the light scattering material in order to prevent the light transmittance of the polarizing film on the front surface of the device from changing and the contrast of the screen from lowering.

The invention according to claim 6 is made under such circumstances, that is, the invention according to claim 6 is
The liquid crystal display device according to claim 4 or 5, wherein the light scattering material is made of an amorphous material.

As such an amorphous material, for example,
Examples thereof include polyvinylbenzene and polytetrafluoroethylene.

In the liquid crystal display device according to the first to sixth aspects, in the case of color display, a color filter layer for coloring transmitted light may be provided on the signal side electrode plate. At this time, a coloring material may be added to the light scattering layer to allow the light scattering layer to directly function as a color filter layer, or a color filter layer may be provided separately from the light scattering layer.

The inventions according to claims 7 and 8 are invented in order to meet such a demand, and the invention according to claim 7 is the liquid crystal display device according to any one of claims 4 to 6. The layer contains a coloring material for coloring transmitted light. On the other hand, the invention according to claim 8 is the liquid crystal display device according to any one of claims 1 to 6. A color filter layer for coloring transmitted light is provided between the transparent electrode and the transparent electrode.

In the invention according to claim 7, as the coloring material, a well-known organic pigment which has been conventionally applied to the color filter layer can be applied, and for example, phthalocyanine green or the like can be used as the green pigment.

In the invention according to claim 8, a known color filter layer can be applied to the color filter layer. For example, a pigment dispersion method color filter formed by using a photosensitive resin in which an organic pigment is dispersed and a photolithography process, a dyeing method color filter formed by dyeing a resin with a dye, an offset printing method, an intaglio offset printing method, or a flexographic method. A printing method color filter formed by a printing method such as a printing method. If necessary, an overcoat layer of organic resin or silicon oxide may be formed on the color filter layer.

In the inventions according to claims 7 and 8, the color material or the color filter layer can use the three primary colors of light, namely red, green and blue. In addition to this, cyan and magenta are also available. , Yellow, and the like (complementary colors of the above three primary colors of light), and white in addition to these four or more colors can also be used.

In the invention according to claims 1 to 8,
As the transparent thin film, an ITO thin film formed by adding tin oxide as a dopant to indium oxide, a thin film formed by adding zirconium oxide, titanium oxide, magnesium oxide, or the like to indium oxide, or aluminum oxide in zinc oxide. It is possible to use a thin film to which is added, or a multilayer thin film in which an indium oxide thin film and the above ITO are laminated. Then, after forming these transparent thin films, they can be processed into the above electrode shape by etching and patterning according to a photolithography process. Incidentally, when the metal thin film and the transparent thin film are etched after forming the metal thin film and the transparent thin film, the metal thin film is etched more largely because the etching rate of the metal thin film is faster than the etching rate of the transparent thin film, and a predetermined pattern is formed. You may not get it. In order to avoid this and accurately form the metal thin film and the transparent thin film having the desired pattern, the substrate temperature is set to 18
A transparent thin film having a high etching rate and being substantially amorphous is formed by keeping it at a low temperature of 0 ° C. or lower, and then this transparent thin film is etched and patterned, and the transparent thin film thus patterned is used as an etching resist. It is desirable to etch and pattern the thin film. The transparent thin film thus formed can be improved in conductivity and visible light transmittance by being patterned by an electrode pattern and then heated and oxidized.

The invention according to claim 9 is based on such a reason, and relates to a method for manufacturing a liquid crystal display device according to claims 1 to 8.

That is, according to the ninth aspect of the invention, the electrode plate having the scanning side electrode for driving the liquid crystal, the other electrode plate having the signal side electrode, and the both electrode plates are provided. In a method of manufacturing a liquid crystal display device including a sandwiched liquid crystal, a metal thin film is formed on a substrate of a scanning side electrode plate, and a substantially amorphous transparent conductive film is formed on the metal thin film. Then, the transparent conductive film and the metal thin film are sequentially etched and patterned by photolithography to manufacture a scanning side electrode plate, and a liquid crystal is sandwiched between the scanning side electrode plate and the signal side electrode plate thus obtained. It is characterized by doing.

In the invention according to claims 1 to 9, on the transparent thin film of the scanning side electrode plate or the transparent electrode of the signal side electrode plate,
As an insulating film, SiO ₂ , MgO, MgF ₂ , ZrO ₂ ,
An inorganic oxide film such as CeO ₂ may be formed.

[0035]

According to the present invention, the scanning-side electrode plate is provided with an electrode composed of two layers of a metal thin film and a transparent thin film arranged so as to cover the metal thin film, on the other side. ,
Since the signal-side electrode plate includes two layers of a transparent electrode and a light-scattering layer on the substrate, incident light such as room light and external light is reflected by the patterned metal thin film, and the light-scattering layer of the signal-side substrate It is scattered by and emitted. Therefore, the scattered light can be observed regardless of the position of the incident light source, and the viewing angle is significantly increased.

Further, since the metal thin film is covered with the transparent thin film, the metal thin film is not deteriorated, and therefore display defects are not generated, and the reliability of the liquid crystal display device can be remarkably increased. Become. In addition, since the transparent electrode is in contact with the thin metal film, the resistance value can be remarkably reduced, crosstalk between the electrodes can be prevented, and the display uniformity can be improved. Become.

According to the invention of claim 9, a metal thin film is formed on the substrate of the scanning electrode plate, and a substantially amorphous transparent conductive film is formed on this metal thin film. Next, since the transparent electrode and the metal thin film are sequentially etched and patterned by photolithography to manufacture the scanning-side electrode plate, it is possible to accurately form the metal thin film and the transparent thin film having a desired pattern.

[0038]

【Example】

(Embodiment 1) As shown in FIG. 1, a liquid crystal display device according to this embodiment has a scanning side electrode plate 1 having a glass substrate 11 having a thickness of 0.7 μm, and a width of 310 μm and a pitch of 330 μm on the glass substrate 11. 0.1 μm thick aluminum thin film 12 provided in a striped pattern, and the aluminum thin film 1 having the same pattern as the aluminum thin film 12
2 and a transparent thin film 13 having a thickness of 0.24 μm, which is aligned and laminated on the signal side electrode plate 2.
A glass substrate 21 of 7 mm, an organic black stripe 22 of 1.0 μm in thickness provided in a stripe shape of 25 μm in width on a portion other than the pixels on the glass substrate 21, and colored in red, green and blue respectively. Printing method color filter layers 23R, 23G and 23B provided in stripes between the black stripes (however, the ends are overlapped on the black stripes), and the aluminum thin film 12 pattern of the scanning side electrode plate 1 The light-scattering layer 24 provided in the same stripe shape and the transparent film having a thickness of 0.24 μm provided in a stripe shape having a width of 95 μm and a pitch of 110 μm (direction orthogonal to the aluminum thin film 12 pattern of the scanning side electrode plate 1). Composed of the electrode 25,
The scanning-side electrode plate 1 and the signal-side electrode plate 2 are integrated by interposing a liquid crystal 3 therebetween and sealing them in the peripheral portion.

The light-scattering layer 24 is formed by dispersing titanium oxide fine particles of anatase structure having an average particle diameter of 0.1 μm in a negative photosensitive resin having a phenol novolac epoxy resin as a skeleton.

The liquid crystal display device according to this example is manufactured by the following steps. That is, first, an aluminum thin film 12 having a thickness of 0.1 μm and a thickness of 0.24 μm are formed on the substrate 11 of the scanning-side electrode plate 1 by sputtering.
And the ITO thin film 13 were formed uniformly over the entire surface. At this time, the substrate 11 was continuously formed at about room temperature without heating. Next, a resist film was formed on the ITO thin film 13 in a pattern of the scanning side electrode according to a known photolithography process, and the ITO thin film 13 was etched and patterned with diluted hydrochloric acid at 25 ° C. for about 1 minute. The aluminum thin film 12 was etched in the same pattern as the ITO thin film 13 with a mixed acid of phosphoric acid / acetic acid / nitric acid at 40 ° C. Then, after that, heat treatment was performed at 250 ° C. for 1 hour to oxidize the ITO thin film 13. IT by this heat treatment
The resistance value of the O thin film 13 decreases and the sheet resistance is about 0.4 Ω /
□, which is 1/20 or less of the case of the ITO thin film 13 single layer before the heat treatment. At the same time, the visible light transmittance of the ITO thin film 13 was improved, and crystallization occurred. Further, along with this heat treatment, aluminum oxide was formed at the end of the aluminum thin film 12, and its corrosion resistance was improved.

The signal side electrode plate 2 is the glass substrate 21.
After forming the black stripe 22 on the above, the red, green, and blue inks of SMX-CF-SME manufactured by Toyo Ink Mfg. Co., Ltd. were used, respectively, and printed by an intaglio offset printing method to obtain color filter layers 23R, 23G, 23B was formed. Next, titanium oxide fine particles having an anatase structure having an average particle diameter of 0.1 μm are dispersed in a negative photosensitive resin having a phenol novolac epoxy resin as a skeleton, and applied on the color filter layers 23R, 23G, and 23B. The film was exposed and developed through a photomask, heated and hardened to form the light scattering layer 24. Then ITO thin film 2
5 was formed into a thick film by sputtering and patterned according to a photolithography process to form a transparent electrode 25.

(Embodiment 2) In the liquid crystal display device according to this embodiment, as shown in FIG. 2, the scanning side electrode plate 4 has a thickness of 0.7.
μ glass substrate 41 and 310 on the glass substrate 41.
.mu.m.times.95 .mu.m provided in a rectangular pattern and a thickness of 0.
It is composed of an aluminum thin film 42 of 15 μm and a transparent electrode 43 of 0.24 μm thickness which is provided in a stripe pattern with a width of 320 μm and a pitch of 330 μm so as to cover the aluminum thin film 42, while the signal side electrode plate 4 is thick. A glass substrate 51 having a thickness of 0.7 mm and a film thickness of about 2 provided on the glass substrate 51 in a stripe shape having a width of about 110 μm.
μm colored light scattering layers 53R, 53G, 53B and width 10
A transparent electrode 55 having a thickness of 0.2 μm and provided in a stripe pattern (direction orthogonal to the aluminum thin film 42 pattern of the scanning side electrode plate 4) having a pitch of 0 μm and a pitch of 110 μm. Side electrode plate 2
The liquid crystal 3 is interposed between the two and sealed at the peripheral portion to be integrated.

The colored light scattering layers 53R, 53G, 5
3B is composed of a printing ink containing 10 to 30% by weight of an organic pigment and about 4% by weight of polytetrafluoroethylene fine particles having a particle diameter of 0.3 μm or less as a light scattering material. The effective area resistance of the transparent electrode 43 is about 1Ω / □.

[0044]

According to the present invention, it is possible to observe the scattered light regardless of the position of the incident light source, the viewing angle is significantly increased, and the reliability of the liquid crystal display device is increased. Is possible. According to the invention of claim 9, the metal thin film and the transparent electrode can be accurately formed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a liquid crystal display device according to an embodiment of the present invention.

[Explanation of symbols]

 1 Scanning Side Electrode Plate 11 Glass Substrate 12 Aluminum Thin Film 13 Transparent Thin Film 2 Signal Side Electrode Plate 21 Glass Substrate 22 Organic Black Stripe 23 Color Filter Layer 24 Light Scattering Layer 25 Transparent Electrode 3 Liquid Crystal 4 Scanning Side Electrode Plate 41 Glass Substrate 42 Aluminum Thin Film 53 transparent electrode 51 glass substrate 53R, 53G, 53B colored light scattering layer 55 transparent electrode

Claims (9)

[Claims] 1. An electrode plate provided with a scanning-side electrode for driving a liquid crystal, another electrode plate provided with a signal-side electrode, and a liquid crystal sandwiched between these two electrode plates. In the liquid crystal display device according to the first aspect, the scanning side electrode plate includes an electrode composed of two layers of a patterned metal thin film on the substrate and a transparent thin film arranged to cover the metal thin film, while the signal side electrode plate is However, the liquid crystal display device is provided with two layers of a transparent electrode and a light scattering layer on the substrate. 2. The liquid crystal cover device according to claim 1, wherein the metal thin film has the same pattern as the transparent thin film in the effective display area of the liquid crystal display device. 3. The liquid crystal display device according to claim 1, wherein in the effective display area of the liquid crystal display device, the metal thin film is formed of a large number of regularly arranged rectangular patterns. 4. The liquid crystal display device according to claim 1, wherein the light scattering layer comprises a transparent resin and light having a refractive index different from that of the transparent resin dispersed in the transparent resin. A liquid crystal display device comprising a scattering material as a main component. 5. The liquid crystal display device according to claim 4, wherein the light scattering material is composed of fine particles having a diameter of 1 μm or less. 6. A liquid crystal display device according to claim 4, wherein the light scattering material is made of an amorphous material. 7. The liquid crystal display device according to claim 4, wherein the light scattering layer contains a coloring material that colors transmitted light. 8. The liquid crystal display device according to claim 1, further comprising a color filter layer for coloring transmitted light between the light scattering layer and the transparent electrode. . 9. An electrode plate provided with a scanning-side electrode for driving a liquid crystal, another electrode plate provided with a signal-side electrode, and a liquid crystal sandwiched between these two electrode plates. In the method for manufacturing a liquid crystal display device, a metal thin film is formed on the substrate of the scanning side electrode plate, a substantially amorphous transparent conductive film is formed on the metal thin film, and then these are formed by photolithography. A liquid crystal display characterized in that a transparent conductive film and a metal thin film are sequentially etched and patterned to manufacture a scanning side electrode plate, and liquid crystal is sandwiched between the scanning side electrode plate and the signal side electrode plate thus obtained. Device manufacturing method.