JPH07181458A - Production of display device and driving method of display device - Google Patents

Abstract

PURPOSE:To realize sufficient brightness and contrast and to easily produce a display device by previously forming a layer of dichromatic dyestuff on the surface of a substrate, introducing a layer of a mixture composed of liquid crystals and high polymer precursors thereon and polymerizing the high polymer precursors, thereby dissolving the dichromatic dyestuff into the liquid crystals. CONSTITUTION:The layer of the dichromatic dyestuff 4 is previously formed on the surface of at least one sheet of the substrate 8 in production of the display device formed by clamping a composite layer composed of the liquid crystals 10 contg. the dichromatic dyestuff 4 and the high polymers 5 between the substrates 1 and 8 having active elements 6 or electrodes layer. The layer consisting of the mixture composed of the liquid crystals 10 and the high polymer precursor's thereafter introduced into the layer of the dichromatic dyestuff 4. The high polymer precursors 10 are then polymerized by UV rays and the dichromatic dyestuff 4 is dissolved into the liquid crystals by heating. Namely, the dichromatic dyestuff 4 is previously applied on the substrate 8, by which the taking in of the dichromatic dyestuff 4 into the high polymers at the time of polymerizing the high polymer precursors 10 is suppressed and the brightness of the display is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to information equipment terminals, televisions,
The present invention relates to a method for manufacturing a display device used for a public notice plate 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 Letter
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. In addition, a technology has also been developed in which, when colorization is performed, a liquid crystal containing a dichroic dye for displaying the three primary colors is sealed in each pixel that displays the three primary colors so as not to reduce the brightness.

[0003]

However, the conventional technique has a problem that when a dichroic dye is used, the dye remains in the polymer and sufficient brightness and contrast cannot be obtained. In addition, when colorization is performed, liquid crystals containing different dyes must be enclosed in adjacent pixels, which poses a problem that encapsulation is extremely difficult. Further, as a driving method of a color display device, a driving method capable of performing sufficient color display has not been presented. Therefore, the present invention is to solve such a problem, and an object of the present invention is to achieve sufficient brightness and contrast in a display device including a dichroic dye and a liquid crystal compound composite layer. An object of the present invention is to provide a method for easily manufacturing a color display device.

Another object of the present invention is to apply an electric field to a plurality of pixels each having a reflective layer on the back surface and comprising an oriented liquid crystal / polymer composite layer containing dichroic dyes having different color tones. Accordingly, in the driving method of the display device for displaying a color image, a new driving method for performing white display, black display and color display is provided.

[0005]

A method of manufacturing a display device according to the present invention may have an active element or an electrode layer.
In a method of manufacturing a display device having a structure in which a liquid crystal and polymer composite layer containing a dichroic dye is sandwiched between two substrates, a dichroic dye layer is formed on at least one substrate surface,
After that, a layer composed of a mixture of liquid crystal and a polymer precursor is introduced on the layer of the dichroic dye, and the polymer precursor is further polymerized by ultraviolet rays or electron beams, and then the dichroic dye is heated or left to stand. Is dissolved in the liquid crystal.

The liquid crystal and the polymer are oriented and dispersed in each other.

Furthermore, the surface of at least one of the substrates, which is in contact with the liquid crystal, is subjected to an alignment treatment.

Further, a partition wall is provided between adjacent pixels in at least one direction, and the dichroic dyes are arranged in different colors.

Further, a display device having a reflective layer on the back surface and displaying a color image by applying an electric field to a plurality of pixels composed of an oriented liquid crystal / polymer composite layer containing dichroic dyes having different color tones is provided. In the driving method, a voltage higher than the saturation voltage (Vsat) that the liquid crystal responds is applied when displaying white, and a voltage lower than the threshold voltage (Vth) that responds to the liquid crystal is applied when displaying black. In order to display a color image, a voltage between Vsat and Vth is applied.

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

[0011]

【Example】

Example 1 In this example, an example in which the present invention is applied to a case of a particle orientation dispersion type black and white display device which may be connected to each other will be described. FIG. 1 briefly shows a method for manufacturing the display device of the present invention. A description will be given along this line.

First, as shown in FIG. 1A, the active element and the electrode 7 were formed on the substrate 8 and the electrode surface was subjected to orientation treatment. A methyl ethyl ketone solution containing 10% by weight of a dichroic dye (a mixture of M361: SI512: M137 = 15: 17: 4 manufactured by Mitsui Toatsu Dye Co., Ltd.) was spin-coated on this surface, and dried at 80 ° C. for 30 minutes. This board 8
The substrate 1 with the electrode 2 that had been subjected to the orientation treatment was fixed with the electrode surface facing inward with a gap of 5 μm maintained, to obtain an empty panel. The liquid crystal / polymer precursor mixture shown below was enclosed in this empty panel.

TL205 (Merck) 9 as liquid crystal
Chiral component R1011 (made by Merck) at 9.2% by weight
Was used as a mixture of 0.8% by weight. 95% by weight of this liquid crystal was mixed with 3.3% by weight of terphenyl methacrylate and 1.7% by weight of terphenyl dimethacrylate as polymer precursors. This is sealed in the empty panel produced earlier, and ultraviolet rays (300 nm to 400 nm,
(3.5 mW / cm2) was irradiated for 10 minutes (see FIG. 1 (I)).

Next, this panel is heated to 60 ° C. to dissolve the dichroic dye 4 in the liquid crystal (see FIG. 1 (u)), and the display side surface is subjected to non-glare treatment and anti-reflection treatment to obtain a display device. Was completed.

The electro-optical characteristics of this display device are shown by the solid line in FIG. How to take the characteristics will be described. First, light was incident from a direction inclined by 20 ° from the normal line of the display device surface, and reflected light in the normal line direction was detected by a photomultiplier tube. While increasing the voltage applied to the display device, the brightness of the reflected light was displayed as a 100-percentage ratio with respect to the case of white paper.

The liquid crystal used in this embodiment is preferably one having a large birefringence, and when used in combination with an active element, one having a large specific resistance is preferable.

The dichroic dye used in this embodiment is preferably one having a dissolution rate in the liquid crystal as small as possible, but a large solubility. That is, it is preferable that the liquid crystal does not melt when it is sealed in the empty panel, but melts after polymerizing the polymer.

The chiral component used in this example can be used in amounts and kinds other than those shown here depending on the application.

The polymer precursor used in this example is preferably one having a birefringence as large as possible, and more preferably,
Those having biphenyl, terphenyl, or quarterphenyl in the side chain or main chain, and the polymerized portion is methacrylate,
Acrylate, crotonate, cinnamate, epoxy and the like can be used.

In the panel constituent member used in this embodiment, first, the substrate and the electrodes must be transparent at least on the front side, and the electrode 7 formed on the back substrate is preferably reflective. With this configuration, double display can be avoided. The active element used in this embodiment is MIM.
Although it is an element, a lateral MIM element, a back-to-back MIM element, a ferroelectric element or the like can also be used. The substrate on which the active element is formed may be the substrate 1. Further, the effect of the present invention can be obtained without using such an active element.

The surface of the display device may not be subjected to non-glare treatment or antireflection treatment.

In the alignment treatment, the electrode surface may be rubbed directly with a cloth or the like, or an alignment film may be formed and rubbed.

COMPARATIVE EXAMPLE 1 In Example 1, an example is shown in which the dichroic dye is dissolved in the liquid crystal in advance and the dichroic dye layer is not formed on the substrate 8. In Example 1, the liquid crystal 9
Dichroic dye (M361: SI51 for 6.4% by weight)
2: M137 = 1.5% by weight: 1.7% by weight: 0.4% by weight). All other conditions were the same as in Example 1. A display device was manufactured in this manner, and its electro-optical characteristics are shown as a broken line in FIG.

(Embodiment 2) This embodiment shows an example in which the present invention is applied to the case of a display device capable of color display. FIG. 3 briefly shows a method for manufacturing the display device of the present invention. A description will be given along this line.

First, as shown in FIG. 3A, a reflective electrode 7 is formed on a substrate 8, a resist layer is formed to a thickness of 5 μm, the electrode is exposed from the back surface, and the unexposed portion is exposed. Was peeled off to form the partition wall 9. After that, an alignment treatment is applied along the partition walls, and M8 as a red dichroic dye is formed on the pixels between the partition walls.
6, M137 as a blue dichroic dye and 10% by weight of a mixture of M361 and M137 as a green dichroic dye.
It was applied as a methyl ethyl ketone solution. 80 ° C
And dried for 30 minutes. A substrate 1 with an electrode 2 having an active element 2 applied with an ultraviolet curable resin M6200 (manufactured by Toagosei Kagaku Co., Ltd.) on the surface of the partition wall 9 formed on the substrate 8 in contact with the opposite substrate and the periphery of the substrate to perform orientation treatment. Was fixed with the electrode surface facing inward while maintaining a gap of 5 μm, and was irradiated with ultraviolet rays to be bonded. Here, the liquid crystal / polymer precursor mixture shown in Example 1 was enclosed in this gap.

Further, from the substrate 1 side, ultraviolet rays (300 nm
(-400 nm, 3.5 mW / cm2) was irradiated for 10 minutes (see FIG. 3 (I)).

Next, this panel is heated to 60 ° C. to dissolve the dichroic dye 4 in the liquid crystal (see FIG. 3 (U)), and the display side surface is subjected to anti-glare treatment and anti-reflection treatment to carry out the present embodiment. An example color display was manufactured. In this embodiment, 640 × 480 pixels were formed for each color and the screen data of the computer was displayed. As a result, a bright color display similar to that of the display device manufactured in the first embodiment could be performed.

Although an MIM element was used as the active element formed on the substrate 1, an MIM element other than the configuration shown here is used.
An element such as a lateral MIM element or a back-to-back MIM element, a TFT element, or a ferroelectric element can be similarly used. The substrate on which the active element is formed may be the reflective substrate side. Further, the effect of the present invention can be obtained without forming an active element.

The liquid crystal used in this embodiment is preferably one having a large birefringence, and when used in combination with an active element, one having a large specific resistance is preferable.

The dichroic dye used in this example is preferably one having a dissolution rate in the liquid crystal as small as possible, but a large solubility. That is, it is preferable that the liquid crystal does not melt when it is sealed in the empty panel, but melts after polymerizing the polymer. The colors are not necessarily red, blue and green, but colors that can reproduce natural colors, such as yellow,
Cyan or magenta may be used.

The chiral component used in this example can be used in amounts and kinds other than those shown here depending on the application.

The polymer precursor used in this example is preferably one having a birefringence as large as possible, and more preferably,
Those having biphenyl, terphenyl, or quarterphenyl in the side chain or main chain, and the polymerized portion is methacrylate,
Acrylate, crotonate, cinnamate, epoxy and the like can be used.

In the panel constituent member used in this embodiment, first, the substrate and the electrodes must be transparent at least on the front side, and the electrode 7 formed on the back substrate is preferably reflective. With this configuration, double display can be avoided.

In the alignment treatment, the electrode surface may be rubbed directly with a cloth or the like, or an alignment film may be formed and rubbed.

The surface of the display device may not be subjected to non-glare treatment or antireflection treatment.

The substrate on which the partition wall 9 is formed may be the front substrate.

Example 3 In this example, an example in which the present invention was applied to the case where a network matrix type was used as the liquid crystal / polymer layer was shown. The same as Example 1 except for the liquid crystal / polymer precursor mixture to be enclosed. The liquid crystal used was RDP21111 manufactured by Rodec, and the polymer precursor was M6200 manufactured by Toagosei Co., Ltd., each of which was 90:10.
And benzophenone as a polymerization initiator.
Wt% was added. This mixture was sealed in the empty panel shown in Example 1 and was exposed to ultraviolet rays (300 to 400 nm, intensity of 100).
mW / cm2, 20 seconds) to polymerize the polymer precursor to form a network matrix, and to dissolve the dichroic dye in the liquid crystal by heat treatment, and further to scatter white light on the back surface of the display device. White paper was placed as a layer, and the display side surface was subjected to antiglare treatment and antireflection treatment to obtain a display device. The empty panel used in this example does not require the alignment treatment performed in Example 1. The electro-optical characteristics of the display device thus manufactured are shown by the solid line in FIG.

The polymer precursor used here is a bifunctional polymerizable substance having a slender liquid crystallinity, and includes Aronix and Reseda macromonomer manufactured by Toagosei Kagaku Co., Ltd., KAYARAD and KAYAMER manufactured by Nippon Kayaku Co., and San Nopco. Nopcomer, SICOMET and Photomer,
Tohto Kasei's Epotote, Neotote, Toprene and Dap Tote, Yuka Shell's Epicoat, Asahi Denka's Adeka Resin, Adeka Optimer and Adeka Opton, ThreeBond's 2200 series, Showa Polymer's Lipoxy and Spyrac The products of Nippon Polyurethane Co., Ltd. and substances similar thereto can be used.

Instead of the white paper arranged on the back surface, a scattering reflection plate (for example, a metal plate having a rough surface or a film in which metal or the like is dispersed and applied) may be used. The white paper or the light-scattering reflector may also serve as the electrode 7.

The antiglare treatment or the antireflection treatment may not be applied.

Comparative Example 2 Here, as a comparative example of Example 3, an example will be described in which a dichroic dye is premixed with a liquid crystal and a polymer precursor. Liquid crystal RDP21111 (9
5.6% by weight) as a dichroic dye M361: SI51
2: M137 = 1.5: 1.7: 0.4 (all are wt%) and 0.8 wt% of the chiral component R1011 are mixed and sealed in an empty panel in Example 1 in which the dye layer is not formed. Polymerization was performed by ultraviolet rays in the same manner as in Example 3, and then white paper was placed on the back surface of the display device to measure electro-optical characteristics (see broken line in FIG. 4).

(Embodiment 4) This embodiment shows an example in which the present invention is applied to the case of a gel network alignment type black and white display device. Basically the same as in Example 1, but
Different materials are used as the polymer precursor, and a bifunctional polymer precursor having an elongated liquid crystal property is used. TL as liquid crystal
203 (Merck) 99.2 wt% chiral component R
A mixture obtained by mixing 0.81% by weight of 1011 (manufactured by Merck) was used. 96% by weight of this liquid crystal was mixed with 3% by weight of Philips C6H as a polymer precursor and 1% by weight of Irgacure 184 (manufactured by Ciba-Geigy) as a polymerization initiator. This was sealed in the empty panel produced in Example 1, and ultraviolet rays (300 nm to 400 nm, 3.5 nm) were applied from the substrate 1 side.
mW / cm2) was irradiated for 10 minutes.

Next, this panel is heated to 60 ° C., the dichroic dye 4 is dissolved in the liquid crystal, and the surface on the display side is subjected to antiglare treatment and antireflection treatment to manufacture the black and white display device of this embodiment. did.

The electro-optical characteristics of this display device are shown by the solid line in FIG.

The polymer precursor used here is preferably a bifunctional polymerizable substance having elongated liquid crystallinity, such as biphenyl diacrylate and its derivatives, Aronix and Reseda macromonomers manufactured by Toagosei Kagaku, and Nippon Kayaku. KAYARAD and KAYAMER, San Nopco's Nopcomer, SICOMET and Photomer, Tohto Kasei's Epotote, Neotote, Toprene and Duptote, Yuka Shell's Epicoat, Asahi Denka's Adeka Resin, Adeka Optimer and Adeka Opton, ThreeBond. 2200 series manufactured by Showa Kogyo Co., Lipoxy and Spirac manufactured by Showa High Polymer Co., Ltd., products of Nippon Polyurethane Co., Ltd., and substances similar thereto can be used.

The surface of the display device may not be subjected to non-glare treatment or antireflection treatment.

COMPARATIVE EXAMPLE 3 In Example 4, an example is shown in which the dichroic dye is dissolved in the liquid crystal in advance and the dichroic dye layer is not formed on the substrate 8. In Example 4, the liquid crystal 9
Dichroic dye (M361: SI51 for 6.4% by weight)
2: M137 = 1.5% by weight: 1.7% by weight: 0.4% by weight). All other conditions were the same as in Example 4. A display device was manufactured in this manner, and its electro-optical characteristics are shown as a broken line in FIG.

Example 5 In this example, the polymer is a network matrix type polymer, and an example in which the present invention is applied to a display device capable of color display will be described. A display device was manufactured basically by the same method and conditions as those shown in the second embodiment. However, the liquid crystal / polymer precursor shown in Example 3 was used, and ultraviolet rays (300 to 400 n) were used.
m, intensity 100 mW / cm2, 20 seconds) to polymerize the polymer precursor, then heat to dissolve the dichroic dye in the liquid crystal, and subject the display side surface to antiglare treatment and antireflection treatment. A color display device of this example was manufactured.
In this example, 640 × 480 pixels were created for each color and the screen data of the computer was displayed. As a result, bright color display comparable to that of the display device manufactured in Example 3 could be performed.

In this embodiment, it is not necessary to align the liquid crystal and the polymer under no electric field, so that it is not necessary to perform the alignment treatment on the substrate surface.

The surface of the display device may not be subjected to non-glare treatment or antireflection treatment.

Example 6 In this example, an example in which the present invention is applied to a display device capable of color display in the form of gel network in which polymers are oriented will be shown. A display device was manufactured basically by the same method and conditions as those shown in the second embodiment. However, the liquid crystal / polymer precursor was prepared in Example 4
UV irradiation (300 to 400 nm, intensity 3.5 mW / cm2, 10 minutes) is used to polymerize the polymer precursor, and then heated to dissolve the dichroic dye into the liquid crystal, The display side surface was subjected to anti-glare treatment and antireflection treatment to manufacture a color display device of this example. In this example, 640 × 480 pixels were formed for each color and the screen data of the computer was displayed. As a result, bright color display similar to that of the display device manufactured in Example 4 could be performed. The surface of the display device may not be subjected to non-glare treatment or antireflection treatment.

(Embodiment 7) In this embodiment, a driving method of a color display device as shown in Embodiments 2 and 6 in which white display is performed by light scattering when an electric field is applied and dark display is obtained by dye absorption when no electric field is applied. An example will be described. Especially here
A driving method will be described for the display device having the configuration as shown in FIG. FIG. 6 qualitatively shows the electro-optical response of each pixel of red, blue and green shown in FIG. The vertical axis represents the brightness of each color of each pixel. According to this, the reflectance is extremely low below Vth and displayed as dark (black) regardless of the color tone of the added dichroic dye, and it is displayed as white due to light scattering when a voltage of Vsat or higher is applied. That is, normal driving without gradation (Vth and Vsat
It is not possible to perform color display with the driving method of selecting (1). Therefore, in the present embodiment, attention is paid to the fact that such a display device can produce the color tone of the added dichroic dye by applying an intermediate voltage between Vth and Vsat. A voltage in the middle of Vsat was applied. Moreover, the brightness of the color of each pixel could be freely changed by changing the voltage applied between Vth and Vsat (see FIG. 6).

In this embodiment, MIM is used as an active element.
FIG. 7 shows a specific example of the voltage applied to the display device when the element is used. FIG. 7 shows a composite waveform of two types of waveforms applied to the common electrode and the segment electrode of the display device. FIG. 7A shows a voltage modulation method, in which white is displayed by applying a voltage (here, 30 V) that causes the liquid crystal to sufficiently respond, and black is displayed by applying a voltage that does not cause the liquid crystal to respond (here, 25 V). , And the electric field in the middle (here, 27.5
By applying V), the color of each pixel, that is, red, blue,
I was able to display green. Further, FIG. 7 (i) shows a pulse width modulation method, which is a voltage (30
V) is applied to display white, a voltage (25V in this case) that does not cause the liquid crystal to respond is applied to display black, and the pulse width is changed between 30V and 25V to display the color of each pixel, that is, red. , Blue, green could be displayed.

However, as can be seen from the above description, it is different from the color display of a color display device in which a normal transmission type color filter is combined. That is,

[0055]

[Table 1]

The correspondence is as follows. Therefore, if the normally used drive circuit is directly connected, correct color reproduction cannot be performed. It is necessary to process the color signal in order to reproduce the correct color. Specifically, the same color display as that of a normal color display device can be performed by driving the voltage with the maximum saturation voltage as the upper limit. To display bright white, a voltage of Vsat or higher may be applied to all pixels.

[0057]

As described above, according to the present invention, by coating the dichroic dye on the substrate in advance, it is possible to minimize the incorporation of the dichroic dye into the polymer when polymerizing the polymer precursor. The brightness of the display could be improved. Further, in a driving method of a display device including pixels including dichroic dyes having different color tones, V
By applying a voltage between th and Vsat, color display was possible. With the present invention, it is possible to fabricate bright black and white or color reflective display devices.

[Brief description of drawings]

FIG. 1 is a diagram simply illustrating a manufacturing method of a display device according to a first exemplary embodiment.

FIG. 2 is a diagram showing electro-optical characteristics of the display devices of Example 1 and Comparative Example 1.

FIG. 3 is a diagram simply illustrating a manufacturing method of the display device according to the second embodiment.

FIG. 4 is a diagram showing electro-optical characteristics of display devices of Example 3 and Comparative Example 2.

5 is a diagram showing electro-optical characteristics of display devices of Example 4 and Comparative Example 3. FIG.

FIG. 6 is a diagram showing electro-optical characteristics of the display device of Example 6.

FIG. 7 is a diagram showing drive waveforms of a display device of Example 7.

[Explanation of symbols]

 1 substrate 2 electrode 3 liquid crystal 4 dichroic dye 5 polymer 6 MIM element 7 electrode 8 substrate 9 partition wall 10 liquid crystal / polymer precursor

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

Claims (6)

[Claims] 1. A method of manufacturing a display device having a structure in which a composite layer of a liquid crystal containing a dichroic dye and a polymer is sandwiched between two substrates which may have active elements or electrode layers,
A dichroic dye layer is formed on the surface of at least one substrate, and then a layer composed of a mixture of liquid crystal and a polymer precursor is introduced on the dichroic dye layer, and then ultraviolet or electron beam is applied. A method for producing a display device, comprising polymerizing a polymer precursor and then heating or leaving it to dissolve the dichroic dye in the liquid crystal. 2. The method for manufacturing a display device according to claim 1, wherein the liquid crystal and the polymer are oriented and dispersed in each other. 3. The method for manufacturing a display device according to claim 2, wherein the surface of at least one of the substrates, which is in contact with the liquid crystal, is subjected to an alignment treatment. 4. The method of manufacturing a display device according to claim 1, wherein the liquid crystal and the polymer are randomly dispersed in each other. 5. The method of manufacturing a display device according to claim 1, wherein partition walls are provided between adjacent pixels in at least one direction, and the dichroic dyes are arranged in different colors. 6. An electric field is provided to a plurality of pixels comprising a liquid crystal / polymer composite layer having a reflective layer on the back side of the liquid crystal / polymer layer as viewed from the user and containing dichroic dyes having different color tones. In a method of driving a display device that displays a color image by applying a voltage, a voltage equal to or higher than a saturation voltage (Vsat) that the liquid crystal responds to is applied when displaying white, and a liquid crystal response is applied when displaying black. A method of driving a display device, wherein a voltage between Vsat and Vth is applied to display a color image by applying a voltage equal to or lower than a threshold voltage (Vth).