JPH07181521A - Display element and its production - Google Patents

Abstract

PURPOSE:To obtain a display element capable of making color display by changing chiral pitches at every small pixel for displaying colors in one pixel and a process for production of such element. CONSTITUTION:Electrode groups 2 are formed on a substrate 1 and thereafter, a photopolymerizable resin is applied thereon and is exposed to form partition walls 10 between pixels. Electrode groups 7 are formed on a substrate 8 facing thereto. The electrode side surfaces of both substrates are subjected to an orientation treatment. Next, a chiral component is dissolved in a methyl ethyl keton and is applied on the pixels on the electrodes 2 formed on the substrate 1. At this time, the concn. of the chiral components is changed by every small pixel in the pixels. Namely, the concn. of the chiral components is changed and the chiral components are applied in such a manner as to attain the pitches to reflect red/green/blue with the small pixels desired to display red/green/blue. The chiral pitch is changed for each of the respective pixels and the partition walls are disposed between the pixels varying in the chiral pitch, by which the display element capable of making bright color display with high reliability is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure and a manufacturing method of a display device used in an information equipment terminal such as a computer, a television, an advertising board and the like.

[0002]

2. Description of the Related Art In recent years, along with the miniaturization and portableness of information equipment, a power saving technology for the device is being developed for long-term use with a battery. In particular, when a liquid crystal display device is used in the display part of the device, a device without a backlight is being actively developed. Among them, polymer dispersed liquid crystal (P
The development of DLC) is remarkable. For example, a display of a type that controls light scattering, such as one in which a liquid crystal and a polymer are dispersed with each other, or one that uses light scattering by applying an electric field to a liquid crystal / polymer layer, is being developed (Japanese Patent Publication No. 3-52).
843, Applied Physics Lette
rs 60 (25) 22 June 1992, JP-A-4-227684, etc.). A technique for improving visibility by mixing a dichroic dye in a liquid crystal has also been developed. However, such a technique cannot provide sufficient contrast.
Further, when a dichroic dye is used, the dye remains in the polymer, and sufficient brightness and contrast cannot be obtained. There is also a problem that a combination with an active element is indispensable for displaying a large capacity. Therefore, as a display device that solves these problems, a technique has been developed in which a conventional chiral nematic phase transition is used, and a polymer matrix is combined with this to provide a memory property (JAPAN DISPLAY '92).
Proceedings page 73).

[0003]

However, in this technique, although the technique in colorization is suggested, it is not disclosed. Furthermore, the manufacturing method is not shown.

Therefore, the present invention is to solve such a problem, and an object of the present invention is to change the chiral pitch for each small pixel for displaying a color in one pixel so that a color display can be achieved. The present invention provides a possible display device and a manufacturing method thereof.

[0005]

A display device and a method for manufacturing the same according to the present invention include a plurality of pixels each including a plurality of small pixels, in which a layer in which a chiral liquid crystal and a polymer are oriented and dispersed is arranged between two substrates. In the provided display element, the chiral pitch is changed according to the color displayed in the small pixel in each pixel.

The wavelength of light reflected by the display element is 40
It is characterized by being 0 nm to 700 nm.

Further, a partition is provided between the small pixels.

Further, a light absorbing layer is arranged on the back side of the liquid crystal and the polymer layer as seen from the observer.

The surface of the display element is subjected to a non-glare treatment and / or an antireflection treatment.

Further, a partition wall for separating the small pixels is provided on at least one of the substrates holding the liquid crystal / polymer layer.
Further, each small pixel is coated or arranged with an amount of the chiral component that determines the chiral pitch of the liquid crystal, the opposing substrates are bonded together, then the liquid crystal and the polymer precursor are sealed, and the chiral component is heated in the liquid crystal. It is characterized in that the polymer precursor is polymerized after it is melted and reaches a desired chiral pitch.

Further, when applying the chiral component,
It is characterized in that the chiral component is dissolved in a solvent.

The present invention will be described in detail below with reference to examples.

[0013]

【Example】

(Embodiment 1) FIG. 1 shows a simple partial sectional view of a display device of this embodiment. First, a panel for enclosing a liquid crystal / polymer precursor will be described. After forming the electrode group 2 on the substrate 1, the photopolymerizable resin M6200 (manufactured by Toagosei Kagaku Co., Ltd.)
The coating was applied to a thickness of μm and exposed to form partition walls between pixels. Further, the electrode group 7 was formed on the substrate 8 facing this.
The electrode side surfaces of these both substrates were subjected to orientation treatment. Next, substrate 1
R101 as a chiral component on the electrode 2 formed above
1 (manufactured by Merck & Co.) was dissolved in methyl ethyl ketone and applied on the pixels (Fig. 1 (A)). At this time, the density of the chiral component was changed for each small pixel in the pixels. That is, a small pixel that wants to display red has a pitch that reflects red (650 nm), and a small pixel that wants to display green has green (520 nm).
In a small pixel that wants to display blue in a pitch that reflects light, the density of the chiral component is changed and applied so that the pitch reflects blue (450 nm).
Then, it was dried at 80 ° C. and bonded to the counter substrate 8 (FIG. 1A).

A liquid crystal / polymer precursor mixture was enclosed in this (FIG. 1 (I)). This liquid crystal / polymer precursor mixture will be described. BL007 (Merck) as liquid crystal,
As the polymer, M6200 was used, and the mixture was liquid crystal: polymer precursor = 98: 2. This is sealed in the above-mentioned empty panel, heated to dissolve out the chiral component, and after reaching a desired chiral pitch, ultraviolet rays (350 nm, 3.
The polymer precursor was polymerized by irradiation with 5 mW / cm2) (Fig. 1 (u)).

Next, a non-glare treatment and an antireflection treatment were applied to the display surface side of this liquid crystal element. Further, a light absorption layer was formed on the back surface side of this display element. Specifically, black paint was applied. Of course, a black film may be attached.

The electro-optical characteristics of each small pixel of the display element thus manufactured were measured and shown in FIG. Here, a photomultiplier tube was arranged in the vertical direction on the surface of the display element, light was made incident from a direction inclined by 20 ° with respect to this, and the reflected light was measured. After applying a rectangular wave having a pulse width of 20 mS and a peak value from 0 V on the horizontal axis of FIG. The solid line indicates that the reflectance was measured while increasing the peak value of the rectangular wave after applying a 45 V pulse in advance to a dark state before measurement. The dashed line was measured by measuring the reflectivity while increasing the peak value of the rectangular wave after applying a 35 V pulse to make it bright. Note that 100% on the vertical axis is the brightness when white paper is placed instead of the display element. According to FIG. 2, it can be seen that when the electric field after applying 45 V is 0, the state is dark, and when the electric field after applying 35 V is 0, the state is bright. That is, it has a memory property. Therefore, time-division driving is possible and large capacity display is possible. In this embodiment, a matrix type electrode structure similar to that of a normal STN display device is used, and 640 × 40
A display of 0 was possible. The drive waveform is shown in FIG. A pulse of 30 V is applied to the scanning electrodes at intervals of 1/400 duty. In order to make the transparent state in synchronization with the scanning signal, the peak value when combined is 35V, and to make it the scattering absorption state, the peak value when combined is 25V. Is applied to the signal electrode. Here, the driving waveform is made alternating in order to prevent electrolytic corrosion due to the direct current of the electrodes and decomposition of the liquid crystal, but it is of course also possible to drive with a direct current or a pulsating waveform. Further, even if the composite waveform is not as shown in FIG. 3, a drive waveform that applies an electric field that causes the liquid crystal to respond in the selection period in principle and holds the alignment state of the liquid crystal in the non-selection period is used. be able to. Since the response speed of the device is about 10 mS, it took 4 seconds to form one screen.

The liquid crystal used in the present invention may be any liquid crystal having a nematic phase. When a liquid crystal having a large birefringence is used, the degree of scattering in the scattering absorption state can be improved.

Regarding the chiral component, a liquid crystal of 400 n is used.
Any object having a force capable of twisting at a pitch capable of reflecting light of m to 700 nm can be similarly used. However, since it is necessary to mix a large amount, it is necessary to use a material that takes a liquid crystal phase after mixing.

Regarding the polymer precursor, methacrylic acid,
Polymeric groups such as acrylic acid and epoxy, and alkyl,
Phenyl, biphenyl and the like can be included in the side chain or main chain. For example, Aronix and Reseda macromonomer manufactured by Toagosei Co., Ltd., KAYAR manufactured by Nippon Kayaku Co., Ltd.
AD and KAYAMER, Nopcomer manufactured by San Nopco, SICOMET and Photomer, Epotote manufactured by Tohto Kasei Co., Neotote, Toprene and Duptote, Epicoat manufactured by Yuka Shell Co., Adeka Resin, Adekaputomer and Adeka Opton, Three Bond Co. 2200 series manufactured by Showa Polymer Co., Ltd., Lipoxy and Spirac manufactured by Showa High Polymer Co., Ltd., products of Nippon Polyurethane, and the like can be used. The content of the polymer precursor is preferably 1% by weight to 10% by weight. If it is less than this, there is no memory. On the other hand, if it is more than this, the driving voltage becomes high, which is not practical.

Regarding the polymerization conditions, it is necessary to optimize the temperature, light intensity and wavelength depending on the polymer precursor used.

Although the thickness of the liquid crystal / polymer layer is 5 μm here, it is preferably between 4 μm and 10 μm. If it is too thin, the memory property deteriorates, and if it is too thick, the drive voltage increases.

Even if the surface of the display element is not subjected to the antiglare treatment or the antireflection treatment, it is effective. (Embodiment 2) In this embodiment, an example in which the partition wall 10 is formed of a sealant in Embodiment 1 has been shown. First, an empty cell for enclosing the liquid crystal will be described. The comb-shaped electrode groups 2 and 7 were formed on the substrate 1 and the substrate 8, and the surfaces thereof were oriented. Further, a UV-curable sealant having a spacer of 5 μm mixed was printed between and around the electrodes 7 on the substrate 8. Next, according to the pattern of the electrodes of the electrode group 7 on the substrate 1, red,
A methyl ethyl ketone solution in which the concentration of the chiral component R1011 was adjusted in order so that the chiral pitch was blue and green was printed and dried. The substrate 8 and the substrate 1 were attached so that the electrode groups were orthogonal to each other (see FIG. 4). Next, ultraviolet rays were irradiated to cure the sealant. The liquid crystal / polymer precursor mixture shown in Example 1 was enclosed in this empty panel, and a display element was produced in the same manner as in Example 1. The same effect as in Example 1 was obtained.

The same members and conditions as in Example 1 can be used as the members and manufacturing conditions. (Example 3) In this example, a method of printing a chiral component and a sealant on the substrate 8 side in Example 2 will be described. FIG. 5 shows a conceptual diagram of the method for manufacturing the display element of this example. The electrode group 7 was formed on the substrate 8 and the surface was subjected to orientation treatment. The shape of the electrode group 7 is sequentially printed with the chiral component solutions of three different concentrations used in Example 2 and dried. Next, a sealant having a spacer of 5 μm mixed was printed on the gap and the periphery of the electrode group 7. This substrate 8 was bonded to the substrate 1 on which the electrode group 2 was formed and subjected to the alignment treatment so that the electrode groups were orthogonal to each other. Thereafter, a liquid crystal / polymer precursor mixture was enclosed and irradiated with ultraviolet rays in the same manner as in Example 1 to produce a display device. The same effect as in Example 1 was obtained.

The same members and conditions as in Example 1 can be used as the members and the manufacturing conditions. (Embodiment 4) In this embodiment, an example is shown in which a partition wall is formed in advance and a chiral liquid crystal that reflects the color to be displayed is enclosed in each small pixel. FIG. 6 shows a method of manufacturing the display element of this example. First, an empty cell for enclosing the liquid crystal will be described.
The comb-shaped electrode groups 2 and 7 were formed on the substrate 1 and the substrate 8, and the surfaces thereof were oriented. Further, a UV-curable sealant having a spacer of 5 μm mixed was printed between and around the electrodes 7 on the substrate 8. The substrate 8 and the substrate 1 were laminated so that the electrode groups were orthogonal to each other. A liquid crystal polymer precursor mixture having the following three types of chiral pitch was enclosed in this empty panel. Liquid crystal BL007 (manufactured by Merck): Polymer precursor M7100 (manufactured by Toagosei Kagaku) =
With 97: 3 as the base, 8.5% of R1011 is mixed to reflect red, 9% of R1011 is mixed to reflect green, and R1011 is mixed to reflect blue. A mixture of 0.5% was prepared. The three types of liquid crystal / polymer precursor mixtures were sequentially enclosed in the above empty panel. Specifically, as shown in FIG. 6, by enclosing one type of liquid crystal and dividing it by A in FIG. 6 of the panel to create an encapsulation port for the next liquid crystal, and encapsulating the next liquid crystal, further in FIG. B
Divide by and enclose the next liquid crystal. After enclosing all the liquid crystals in this manner, ultraviolet rays were irradiated to polymerize the polymer precursor. A non-glare treatment and an antireflection treatment were applied to the display side surface of this display element, and a light absorbing agent was applied to the back side surface to complete the display element. The display performance was similar to that in Example 1.

The first embodiment can be used for the members to be used, manufacturing conditions and the like.

[0026]

As described above, according to the present invention, it is possible to provide a highly reliable display device capable of bright color display by changing the chiral pitch for each pixel and providing partition walls between the pixels having different chiral pitches. It was Further, as a manufacturing method thereof, the display device of the present invention can be easily manufactured by applying the chiral component to the substrate in advance.

By using the present invention, a bright full-color reflective display device can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a simple partial cross-sectional view of a display element according to a first embodiment.

FIG. 2 is a diagram showing electro-optical characteristics of the display element in Example 1.

FIG. 3 is a drive waveform diagram when time-divisionally driving the display element according to the first embodiment.

FIG. 4 is a partial sectional view showing a method of manufacturing a display element according to a second embodiment.

FIG. 5 is a partial cross-sectional view showing the method of manufacturing the display element according to the third embodiment.

FIG. 6 is a partial sectional view showing a method of manufacturing a display element according to a fourth embodiment.

[Explanation of symbols]

 1 substrate 2 electrode 3 liquid crystal / polymer precursor layer 4 liquid crystal / polymer layer 5 chiral component layer 7 electrode 8 substrate 9 light absorption layer 10 partition wall 11 non-glare layer and antireflection layer

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hidehito Iizaka Seiko Epson Co., Ltd. 3-3-5 Yamato, Suwa City, Nagano Prefecture (72) Inventor Yutaka Tsuchiya Seiko Ecson 3-3-5, Suwa City, Nagano Prefecture Within the corporation

Claims (7)

[Claims] 1. A display element comprising a plurality of pixels each comprising a plurality of small pixels in which a layer in which a chiral liquid crystal and a polymer are oriented and dispersed is arranged between two substrates, and display is carried out in each of the small pixels. A display element characterized in that the chiral pitch is changed according to the color. 2. The wavelength of light reflected by the display element is 400.
The display element according to claim 1, wherein the display element has a thickness of from nm to 700 nm. 3. The display device according to claim 1, wherein a partition is provided between the small pixels. 4. The display device according to claim 1, wherein a light absorption layer is arranged on the back side of the liquid crystal and the polymer layer when viewed from an observer. 5. The display element according to claim 1, wherein the surface of the display element is subjected to a non-glare treatment and / or an antireflection treatment. 6. A partition for isolating the small pixels is provided on at least one of the substrates holding the liquid crystal / polymer layer, and each small pixel is coated with a chiral component in an amount that determines the chiral pitch of the liquid crystal. After arranging them, the opposing substrates are bonded together, and then the liquid crystal and the polymer precursor are sealed, and the chiral component is dissolved in the liquid crystal by heating, and the polymer precursor is polymerized at the desired chiral pitch. A method for manufacturing a display device having a feature. 7. The method of manufacturing a display element according to claim 6, wherein the chiral component is dissolved in a solvent when the chiral component is applied.