JPH0728036A - Display device - Google Patents

Abstract

PURPOSE:To improve the pressure resistance of a display device formed by orienting and dispersing a liquid crystal and polymer with each other and to enable combination with an information input device. CONSTITUTION:In the display device constituted by orienting and dispersing liquid crystal 3 and polymer 5 with each other, a pressure buffer layer 9 and a surface protective layer 11 are arranged. As a result, the display device with the information input device having the good contrast, visibility and pressure resistance is easily produced. The production of the reflection type color large- capacity display with the input information of the pressure resistance type having the good contrast and bright color is possible as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a display device used for a man-machine interface, such as a display unit of an information equipment terminal, a television and a home electric appliance.

[0002]

2. Description of the Related Art In recent years, the need for a bright, power-saving display device that does not use a polarizing plate has increased, and research and development of polymer-dispersed liquid crystal display devices have been active. For example, liquid crystal is encapsulated and dispersed in a polymer (Fig. 2, Japanese Patent Publication No. 3-52843), or liquid crystal and polymer precursor are mixed and polymerized to cause phase separation (US Pat. No. 4,994,204, etc.). .

[0003]

However, these display devices have a problem that sufficient brightness and contrast cannot be obtained. Therefore, recently, a reflective liquid crystal display device in which a polymer and a liquid crystal are aligned and dispersed with each other has been developed (European Patent Publication EP0488116A2). According to this, an extremely bright display with good contrast can be performed. Moreover, since the driving voltage is low and the specific resistance is high, it can be driven by a two-terminal element or a three-terminal element. However, in this display device, the orientation of the polymer particles inside is disturbed by the pressure, and the contrast is lowered. When a rigid protective substrate is placed on the surface to solve this problem, reflection occurs at the substrate interface,
There is also a problem that the display becomes extremely difficult to see. Therefore, the present invention is to solve these problems, and an object of the present invention is to provide a display device that is resistant to external pressure, and further to provide a display device that does not easily become dark even when combined with an information input device. It is an object.

[0004]

The display device of the present invention comprises two
In a display device in which a liquid crystal and a polymer are oriented and dispersed with each other between a pair of substrates with electrodes, a pressure buffer layer and a surface protective layer are arranged on the front side of the substrate sandwiching the liquid crystal and the polymer. An information input device, for example, a touch panel, is also characterized in that it also serves as the surface protection layer. Further, the refractive index difference between the pressure buffer layer and the substrate used is within 0.2. The details will be described below with reference to examples.

[0005]

【Example】

(Example 1) In this example, an example in which a photocurable transparent rubber is used as a pressure buffer layer is shown. FIG. 1 shows a simple cross-sectional view of the display device of this embodiment. First, a panel for enclosing the liquid crystal will be described. A comb-shaped transparent electrode 2 was formed on the substrate 1 on the front side, and its surface was subjected to an alignment treatment. A signal electrode 13 was formed by laminating chromium and tantalum on the substrate 8 on the back side. Next, this surface was anodized to form an insulating layer 12, and a reflective (here, aluminum was used) pixel electrode 7 was formed, and the surface was further subjected to an alignment treatment. Although only three pixels are shown in FIG. 1, 640 × 480 pixels are actually formed in a 4-inch substrate. The two substrates thus prepared were fixed by sticking their peripheries with the electrode surface inside and keeping the distance between the substrates at approximately 5 μm. Next, the liquid crystal and polymer precursor mixture sealed in this gap will be described. MJ901025 as liquid crystal
CB as a chiral component
2.5% of 15 (manufactured by Merck) as a dichroic dye M3
A mixture of 61: SI512: M34 (both manufactured by Mitsui Toatsu Dyestuff Co., Ltd.) was mixed at 2% and used. As a polymer precursor, terphenyl methacrylate was used in an amount of 5% based on the above liquid crystal mixture. The above was mixed by heating and enclosed in the empty panel described above. Then, from the front of the panel at 50 ° C, 3
The polymer was precipitated from the liquid crystal by irradiating with ultraviolet rays of 0 to 400 nm and 3 mW / cm ² . Next, a thermosetting rubber (refractive index 1.5) having a thickness of 0.5 m is provided on the front side of the liquid crystal panel.
Then, a 0.5 mm thick acrylic plate having a non-glare surface was applied as a protective substrate.
The thermosetting rubber was rubberized overnight to complete the display device of this example.

In the display device thus manufactured, the orientation was not disturbed even if a weight of 1 Kg was applied from the surface using a ball-point pen. In contrast, in the display device (see FIG. 2) in which the pressure buffer layer was not sandwiched, the orientation was disturbed at 500 g in the same test. Furthermore, when a non-reflective coating was applied to the surface of this protective substrate, the reflection of scenery was reduced and the visibility was greatly improved.

As the pressure buffer layer, a rubbery material which is transparent and has a refractive index of 1.3 to 1.7 can be generally used. Even if the refractive index is not within this range, reflection at the substrate interface is conspicuous, but there is a pressure buffering effect.

The liquid crystal which can be used in this embodiment is preferably a liquid crystal having a high specific resistance and a high reliability in order to be combined with an active element, and TL202 manufactured by Merck is preferably used as at least one component.

The polymer precursor that can be used in the present embodiment is preferably a compound in which a group having a refractive index anisotropy such as biphenyl, terphenyl and tolan is bonded to a polymerizable group, more preferably biphenyl. It is a derivative of methacrylate, terphenyl methacrylate, and tranmethacrylate.

It is not necessary to use the dichroic dye used in this embodiment, but the use improves the visibility. In that case, it is necessary to use a material having good light resistance, and dichroic dyes such as anthraquinone and pyrene are preferable.

The thickness of the liquid crystal / polymer layer in this embodiment is 3 μm.
To 20 μm, more preferably 4 μ
m to 7 μm is preferable. If it is 3 μm or less, the scattering becomes weak, and if it is 20 μm or more, the active element cannot be driven.

(Embodiment 2) In this embodiment, an information input device (here, a touch panel) is used as a protective substrate, and
An example in which a polymer orientation layer is sandwiched between a three-terminal element substrate and a counter substrate is shown. FIG. 4 is a diagram simply showing a cross section of the display device of this embodiment. An electrostatic capacitance type was used as the information input device, but not limited to this type, various types such as a resistance type, an ultrasonic type, and a light emitting-sensor type can be used. The surface of the information input device was subjected to non-glare processing to prevent the reflection of scenery. Further, in order to prevent reflection at the internal interface of the information input device, a non-reflective coating was applied to the internal interface (this treatment is not necessary).

A display device was completed in the same manner as in Example 1 by using this information input device as a protective substrate in Example 1. In the display device thus manufactured, the orientation of the liquid crystal / polymer layer on the back side was not disturbed even when pen input was performed. Further, it was significantly brighter (about the same as white paper), had a high contrast (contrast = 8: 1), had less surface reflection, and had excellent visibility as compared with the conventional display device with an information input device. Further, since the surface protective layer also serves as the information input device, the weight increase can be suppressed. In this embodiment, the surface of the information input device was not coated with an antireflection coating,
For example, when a friction-resistant and stain-resistant non-reflective coating containing fluorine is applied, the contrast and the visibility are further improved, and the use thereof is less likely to reduce the effect.

(Embodiment 3) This embodiment shows an example in which the present invention is applied to a display device of a simple matrix or static drive. FIG. 6 shows a simple sectional view of a display device in which a pressure buffer layer and a surface protective layer are combined. FIG. 7 shows a simple sectional view of a display device in which a pressure buffer layer and an information input device as a surface protection layer are combined. Example 2 is the same as Example 1 and Example 2 except that the two-terminal element or the three-terminal element is omitted.

As a result, the same effects as those of the first and second embodiments can be obtained in a simple matrix or static drive display device.

(Embodiment 4) In this embodiment, Embodiments 1, 2,
In Example 3, an example in which a gas such as air is used as the pressure buffer layer is shown. FIG. 3 is a diagram simply showing the display device of this embodiment. Since the incident light is reflected between the substrate holding the liquid crystal and the protective substrate, the brightness contrast is reduced, but the pressure buffering effect is great, and the alignment is not disturbed at all until the protective substrate bends and contacts the display element. It was When gas is used as the buffer layer, the antireflection coating is applied to the interface between the substrate and the gas (see FIG. 3) to improve the contrast and visibility. In addition to gas, liquid or the like can be used as well.

(Embodiment 5) In this embodiment, Embodiments 1, 2,
3 shows an example in which a liquid is used as the pressure buffer layer. Here, matching oil was used as the pressure buffer layer. The liquid used here is preferably a non-volatile liquid. When using a liquid, it is necessary to mold the periphery so that the liquid does not leak. The same effect as in Examples 1, 2 and 3 was obtained.

(Embodiment 6) This embodiment is based on Embodiments 1, 2,
An example in which a lateral back-to-back type MIM element substrate is used as the element substrate used in Nos. 4 and 5 will be shown. Since other configurations are the same as those in the previous embodiment, only the element substrate is shown here. FIG. 8 shows the element substrate used in this example. This element has a small element capacity and is a preferable element for driving the liquid crystal / polymer layer used in the present invention. By using this element and combining the above-mentioned examples, a large-capacity display device which is bright and has good contrast and which is strong against external pressure can be manufactured.

The element structure shown here is an example of a lateral back-to-back type MIM element, and if the elements are the same in principle, they can be similarly used.

Other two-terminal elements include PLZT and P
A ferroelectric element having VDF sandwiched between electrodes can also be used.

(Embodiment 7) This embodiment is the embodiment 1, 4, 5
An example using a TFT element substrate as the element substrate used in FIG. Since other configurations are the same as those in the previous embodiment, only the element substrate is shown here. A rough view of the TFT element substrate is shown in the TFT element substrate in FIG. The TFT element can obtain a high voltage applied to the liquid crystal / polymer layer particularly when amorphous silicon is used, and is a preferable element for driving the liquid crystal / polymer layer used in the present invention. By using this element and combining the above-mentioned examples, a large-capacity display device which is bright and has good contrast and which is strong against external pressure can be manufactured.

The TFT element used here may use polysilicon in addition to the one using amorphous silicon,
At this time, since the liquid crystal driver can be built in the element substrate, the display device can be downsized. At this time, if a silicon wafer is used for the element substrate, a TFT and a driver with extremely good characteristics can be formed, and other circuits (for example, a controller circuit) are integrated on the back surface with respect to the surface on which the element is formed. can do.

(Embodiment 8) In this embodiment, Embodiments 1, 2,
3, 4, 5, 6, and 7 show examples in which color filters are combined. FIG. 5 is a simple diagram showing an example of the display device of this embodiment. The color filter may be placed at the position shown in FIG. 5 or may be placed in front of the reflective electrode 7. As for the color of the color filter, three colors of red, blue and green are used here, but other colors may be used (for example, yellow, cyan and magenta). By combining the above example with a color filter, a display device having good pressure resistance including color information can be manufactured.

(Embodiment 9) In this embodiment, Embodiments 1, 2,
An example in which the substrate on which the active element is formed is arranged on the front side and the counter substrate on which the reflective electrode is formed is arranged on the back side is shown for each of 4, 5, 6, 7, and 8. Similar effects were obtained with such a configuration.

[0025]

As described above, according to the present invention, the pressure resistance of the display device can be improved by providing the pressure buffer layer and the surface protection layer. With the present invention, the contrast,
It is possible to easily manufacture a display device with an information input device that has good visibility and pressure resistance, and by combining color filters, a reflective color large-capacity display with a vivid pressure resistant information input device that has good contrast and is bright and vivid It is also possible to manufacture

[Brief description of drawings]

FIG. 1 is a diagram illustrating a simple cross section of a display device according to a first embodiment.

FIG. 2 is a diagram showing a simple cross section of a conventional display device.

FIG. 3 is a diagram showing a simple cross section of a display device in Example 1.

FIG. 4 is a diagram showing a simple cross section of a display device according to a second embodiment.

FIG. 5 is a diagram showing a simple cross section of a display device according to an eighth embodiment.

FIG. 6 is a diagram showing a simple cross section of a display device according to a third embodiment.

FIG. 7 is a diagram showing a simple cross section of a display device according to a third embodiment.

FIG. 8 is a diagram showing a simple cross section of a display device according to a sixth embodiment.

[Explanation of symbols]

 1 substrate 2 electrode 3 liquid crystal 4 dichroic dye 5 polymer 6 anti-reflection coat 7 reflective electrode 8 substrate 9 pressure buffer layer 10 color filter 11 surface protection layer 12 insulating layer 13 signal electrode 14 source electrode 15 gate electrode 16 semiconductor layer 17 Drain electrode 18 Gate insulating layer 19 Touch panel 20 Tantalum layer

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hidehito Iizaka 3-3-5 Yamato, Suwa City, Nagano Seiko Epson Corporation

Claims (5)

[Claims] 1. In a display device in which a liquid crystal and a polymer are dispersed between two substrates with electrodes, the liquid crystal and the polymer are aligned with each other, and a pressure buffer is provided on the front side of the substrate sandwiching the liquid crystal and the polymer. A display device comprising a layer and a surface protection layer. 2. The display device according to claim 1, wherein the surface protection layer also serves as an information input device. 3. The display device according to claim 2, wherein the information input device is a touch panel. 4. The display device according to claim 1, wherein the surface protective layer is subjected to a non-glare treatment. 5. The display device according to claim 1, wherein a difference in refractive index between the pressure buffer layer and the substrate used is within 0.2.