JP2001265262A - Manufacturing equipment for electrophoretic display devices - Google Patents

Abstract

[PROBLEMS] To easily and uniformly arrange charged electrophoretic particles in a dispersion liquid in each display element even when a gap between two substrates is extremely small and a flexible substrate or the like is used. Provided is a manufacturing apparatus for a high-quality electrophoretic display device. SOLUTION: This is an apparatus for manufacturing an electrophoretic display device having at least a substrate having charged electrophoretic particles, a dispersion medium in which the electrophoretic particles are dispersed, and an electrode, wherein the electrophoretic particles 12 are dispersed. Storage means 14 for storing the dispersion liquid 13, a means 17 for stirring the dispersion liquid, a substrate holding means 19 for holding a substrate 18 in the dispersion liquid, and a voltage applied to an electrode formed on the substrate. An electrophoretic display device manufacturing apparatus, comprising: means 110 for applying charged particles to deposit charged electrophoretic particles on electrodes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for manufacturing an electrophoretic display device. More specifically, the present invention relates to an apparatus for manufacturing an electrophoretic display device in which display is performed by moving electrophoretic particles between electrodes.

[0002]

2. Description of the Related Art In recent years, with the development of information equipment, needs for low power consumption and thin display devices have increased, and research and development of display devices meeting these needs have been actively conducted. Among them, the liquid crystal display device is capable of electrically controlling the arrangement of liquid crystal molecules and changing the optical characteristics of the liquid crystal, and has been actively developed and commercialized as a display device capable of meeting the above needs.

[0003] However, these liquid crystal display devices have not yet sufficiently solved the difficulty in seeing characters on the screen due to the angle at which the screen is viewed or reflected light, and the visual burden caused by flickering and low brightness of the light source. For this reason, research on a display device with a small burden on vision is being actively studied.

[0004] Reflective display devices are expected from the viewpoints of low power consumption and reduction of the burden on the eyes. As one of them,
Harold D. An electrophoretic display device invented by Lees et al. (US Pat. No. 3,612,758) is known. In addition, an electrophoretic display device is disclosed in JP-A-9-185087.

FIG. 2 shows the above-mentioned conventional electrophoretic display device and its operating principle. The electrophoretic display device 25 is composed of a charged electrophoretic particle 23 and an insulating liquid 2 in which a coloring dye is dissolved.
4 and a pair of electrodes 21 and 22 facing each other with the dispersion layer interposed therebetween. By applying a voltage to the dispersion layer via the electrodes 21 and 22, the electrophoretic particles 23
Is attracted to an electrode having the opposite polarity to the charge of the particle itself. The display shows the color of the migrating particles 23 and the migrating particles 2
Insulating liquid 24 in which a coloring dye different from the hue 3 is dissolved
Is done by the color.

That is, when the first electrode 21 is used as a negative electrode and the second electrode 22 is used as a positive electrode, the positively charged electrophoretic particles 23 move to the surface of the first electrode 21 close to the observer, and 2
1 and the color of the migrating particles 23 is displayed (FIG. 2).
(B)).

Conversely, when the first electrode 21 is a positive electrode and the second electrode 22 is a negative electrode, the positively charged particles 23 move to the surface of the second electrode 22 far from the observer, and The color of the coloring pigment which adheres and is contained in the insulating liquid 24 is displayed (see FIG. 2A).

Recently, an electrophoretic display device having a novel structure has been reported (JP-A-11-202804). Unlike the conventional electrophoretic display device, the electrophoretic display device performs display by moving the charged electrophoretic particles in the horizontal direction with respect to the substrate. Electrodes for driving the charged electrophoretic particles are formed by lamination on one of the substrates, and the display emits light or dark depending on how the electrophoretic particles spread due to a difference in the electrode area as viewed from the display surface. The feature of this method is that the display utilizes the spread of the charged electrophoretic particles, so that a transparent dispersion can be used. Therefore, by using a color filter layer or the like, colorization can be performed relatively easily. In addition, since the two electrodes are formed on one substrate, the problem of alignment of the two electrodes and mounting of wiring and the like are simplified.

Since the display on the electrophoretic display device largely depends on the concentration of the charged electrophoretic particles dispersed in the dispersion, the charged electrophoretic particles are uniformly dispersed over the entire display surface in order to obtain a high-quality display. Need to be done. As a device for dispersing charged electrophoretic particles in a conventional electrophoretic display device, there are the following two methods.

First, after two substrates are bonded together with a certain gap, the pressure is reduced, then the substrates are immersed in a dispersion liquid in which charged electrophoretic particles are dispersed, and the pressure is returned to normal pressure to reduce the gap. This is an apparatus for injecting a dispersion liquid in which charged electrophoretic particles are dispersed (Japanese Patent Laid-Open No. 11-38898).

Second, the one-sided substrate on which one electrode is formed is placed in the fluid reservoir on which the counter electrode is formed,
This is a device for injecting a suspension medium in which charged electrophoretic particles are dispersed and applying a certain electric field to attach the charged electrophoretic particles to the electrode on one side substrate. This apparatus is the apparatus shown in FIG. 3 (Japanese Patent Publication No. Hei 8-502599).

[0012]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. 11-3 is disclosed.
In JP-A-8898, there is no problem when the gap between the substrates is large, but when the gap is reduced, a phenomenon that the flow of the charged electrophoretic particles becomes worse with respect to the flow of the dispersion liquid appears, and the charged electrophoretic particles near the injection port appear. However, there has been a problem that the concentration of the compound becomes high and uniform dispersion becomes difficult.

On the other hand, in the method disclosed in Japanese Patent Application Laid-Open No. 8-502599, charged electrophoretic particles can be adhered over the entire surface of the substrate 32 using the apparatus 31 shown in FIG. However, since the adhesion amount of the charged electrophoretic particles greatly depends on the gap length between the electrode of the substrate 32 and the electrode 33 on the device side, the flexible substrate is used as the substrate for the electrophoretic display device, and the concentration of the charged electrophoretic particles is increased. There is a problem that the distribution becomes non-uniform. Further, in this method, an electrode 33 having the same area as the area of the substrate 32 to which the charged electrophoretic particles are attached has to be prepared on the apparatus side, which is a major problem in terms of mass productivity and manufacturing cost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has been described in connection with manufacturing an electrophoretic display device.
Manufacture of high-quality electrophoretic display devices that can easily and uniformly arrange charged electrophoretic particles in a dispersion liquid in each display element even when the gap between two substrates is extremely small or when a flexible substrate is used It is intended to provide a device.

[0015]

That is, the production apparatus of the present invention is the following invention. The present invention is an apparatus for manufacturing an electrophoretic display device having at least a charged electrophoretic particle, a dispersion medium in which the electrophoretic particle is dispersed, and a substrate on which electrodes are formed, wherein the charged electrophoretic particles are dispersed. Storage means for storing the obtained dispersion, means for agitating the dispersion, substrate holding means for holding a substrate in the dispersion, and electrophoresis by applying a voltage to an electrode formed on the substrate. An apparatus for manufacturing an electrophoretic display device, comprising: means for depositing particles on an electrode.

The above-described manufacturing apparatus of the present invention is characterized in that it further comprises storage means for two or more dispersions having different concentrations of charged electrophoretic particles. Further, the substrate holding means has a function of transporting the substrate and a mechanism for swinging and rotating the substrate. Further, the production apparatus further comprises a means for measuring the concentration of the dispersion in which the charged electrophoretic particles are dispersed.

Further, the manufacturing apparatus further comprises means for measuring the concentration of the charged electrophoretic particles collected on the substrate. Furthermore, the means for applying a voltage to the electrode is continuously performed while switching the polarity between positive and negative.

According to the manufacturing apparatus of the present invention, charged electrophoretic particles can be uniformly attached to a substrate on which two opposing electrodes are formed on the same substrate, and the apparatus is located at a position facing the substrate. Because there is no need to arrange the side electrode,
At the same time, the process of attaching charged electrophoretic particles can be performed on many substrates, which is very excellent in terms of mass productivity and manufacturing cost.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
FIG. 1 is a schematic sectional view showing an example of the apparatus for manufacturing an electrophoretic display device according to the present invention. The electrophoretic display device manufacturing apparatus 11 of the present invention includes a dispersion 13 in which charged electrophoretic particles 12 are dispersed.
And a second container 1 holding a dispersion 15 containing no charged electrophoretic particles 12.
6 and a stirring means 1 for stirring these dispersions 13 and 15
7, a substrate holding means 19 for holding a substrate 18, and a voltage applying means 1 for applying a voltage to electrodes formed on the substrate.
At least 10.

More preferably, the substrate holding means 19 has a function of transporting and swinging the substrate 18.
Further, a first concentration detecting means 111 for detecting the concentration of the charged electrophoretic particles 12 collected on the electrode;
It has a second concentration detecting means 112 for measuring the concentration of the charged electrophoretic particles 12 therein, and a control means 113 for centrally controlling these means.

As the material of the first and second containers 14 and 16, if the material does not elute impurities affecting the electrophoretic particles 12 and the dispersion liquid 13, a material such as glass, various resins, and metals can be used. Is also good.

The stirring means 17 may be any means capable of stirring the liquid. Usually, the mixture is stirred using a stirrer or the like, but the mixture may be stirred by circulating the liquid using a liquid feed pump or the like.

The substrate holding means 19 has a function of securely holding the substrate 18, and preferably has a transport function. More preferably, the held substrate 18 is
It has the function of swinging inside. The swing may be any movement such as front and rear, left and right, up and down, and rotation of the substrate 18. The substrate holding means 19 can hold one or more substrates 18.

As a usable substrate material, in addition to glass and a hard thick-film plastic material, a thin film of polyethylene terephthalate, polyimide, polycarbonate, polyphenylene sulfide or the like having a thickness of several tens μm is used.
m can be used. The reason why such a thin and flexible substrate can be used is that there is no need to use a counter electrode, and it is not necessary to consider the gap between the substrates.

The voltage applying means 110 applies a voltage to the electrodes formed on the substrate 18, and usually applies a voltage of about 0 to 200V. Also for two electrodes,
Both AC and DC can be applied, but AC is preferably used. In the case of alternating current, there is no particular limitation on the frequency, but usually about 0.1 to 10 Hz is used. There is no particular limitation on the voltage application waveform. By changing voltage application conditions such as voltage, frequency, and applied waveform, the amount of charged electrophoretic particles deposited can be easily controlled.

The optical density detecting means 111 for detecting the concentration of the charged electrophoretic particles 12 collected on the electrode detects the optical density when the charged electrophoretic particles 12 are driven by applying an AC voltage to the electrode on the substrate. Is what you do. As a detection method,
Any device that can measure optical density may be used.

The concentration detecting means 112 for measuring the concentration of the charged electrophoretic particles 12 in the dispersion liquid 13 is provided in the first container 14. The concentration of the charged electrophoretic particles 12 in the dispersion liquid 13 that is reduced by the deposition of the charged electrophoretic particles 12 on the substrate 17 is detected. Any detection method may be used as long as the density can be measured. This means may be provided in the second container 16 as well.

Control means 1 for centrally controlling the above means
As 13, a personal computer or the like is usually used. It has a function of intensively performing control for depositing desired charged electrophoretic particles on the electrode, such as control of holding, transporting and swinging of the substrate, control of voltage application conditions, detection and correction of the concentration of charged electrophoretic particles, and the like.

An electrophoretic display device can be manufactured using the present device as follows. The first container is filled with a dispersion in which the charged electrophoretic particles are dispersed. In the second container,
Fill the dispersion without charged electrophoretic particles. A substrate manufactured by a method disclosed in Japanese Patent Application Laid-Open No. 11-202804 or the like is placed on the substrate holding means. Two electrodes are stacked on the substrate, the electrodes are connected to a voltage application circuit, and the substrate is immersed in the dispersion of the first container.
Next, a voltage is applied between the electrodes. Next, an AC voltage is applied. During the application of the voltage, the solution on the electrode surface of the substrate is made to constantly flow by the substrate holding means or the solution stirring means, so that a fresh liquid is always supplied onto the electrode.
After the charged electrophoretic particles are sufficiently deposited on the electrodes, the substrate is transported to the second container while the voltage is being applied, the substrate is immersed in the second solution, and the voltage is applied alternately to the positive and negative sides, and the excessive charged electrophoresis is performed. Remove particles, poorly charged electrophoretic particles, etc. By this operation, charged electrophoretic particles having uniform characteristics can be uniformly arranged in each display element. Next, the substrate is lifted, and the contrast on the electrode is determined by the substrate concentration detecting means. If the contrast is sufficient, the operation is terminated, and the process proceeds to a post-process for assembling the display device such as bonding the second substrate. As a post-process, replenishment of the electrophoretic dispersion medium, sealing with the display surface side substrate, installation and connection of an electric circuit, and the like were performed to complete the electrophoretic display device.

If it is determined that the contrast is insufficient or the uniformity is low, the step of attaching charged electrophoretic particles and the step of removing irregular particles may be performed a plurality of times.

[0031]

Embodiments of the present invention will be described below.

Example 1 An electrophoretic display device was manufactured using the manufacturing apparatus of the present invention shown in FIG. Dispersion (trade name: Isopar, manufactured by Exxon Corporation) containing aliphatic hydrocarbon as a main raw material has an average particle diameter of 1 to 2
A liquid in which black electrophoretic particles of about μm and a charge control agent were dispersed was placed in a first container. As the positive charge control agent,
Naphthenic acid metal salts (cobalt, manganese, iron, etc.), zirconium octenoate and the like are used, and as the negative charge controlling agent, lecithin, calcium petroleum sulfonate, calcium alkylbenzene sulfonate, sodium dioctyl sulfonate, alkyl alanine and the like are used. Can be

Next, a dispersion containing no charged electrophoretic particles was placed in a second container. In each of the first and second containers, the dispersion was slowly stirred with a magnetic stirrer. The substrate has a length of 300 mm, a width of 200 mm, and a thickness of 120 μm.
Was used. The substrate on which the electrodes were formed was placed on substrate holding means, and the electrodes were connected to a voltage application circuit. As the voltage, a rectangular wave of ± 80 V was applied at a frequency of 1 Hz. This substrate was placed in a first container, and held for 10 minutes while rocking the substrate back and forth by the substrate holding means, thereby depositing charged electrophoretic particles on the electrodes. During these steps, the concentration of the charged electrophoretic particles in the first container was constantly measured by the second concentration detecting means. After the deposition of the charged electrophoretic particles, the substrate was transferred to the second container while applying a voltage. The charged electrophoretic particles were driven in the second container for 5 minutes.

After driving, the substrate was pulled up, and the concentration of the charged electrophoretic particles collected on the electrode was measured by the first concentration detecting means. As a result of the measurement, a sufficient contrast was obtained, and thus the deposition of the charged electrophoretic particles was terminated.

All of these process controls were performed using a controller. After the completion of the deposition, another transparent substrate was bonded to the substrate on which the electrodes were formed so as to sandwich the charged electrophoretic particles and the dispersion. The gap between the substrates was 30 μm. Further, as a post-process, replenishment of a dispersion medium for electrophoresis, sealing with a display surface side substrate, installation and connection of an electric circuit, and the like were performed to complete an electrophoretic display device.

When the display of the manufactured electrophoretic display device was performed, the contrast distribution in the plane was very uniform despite the very small gap.

[0037]

As described above in detail, when the manufacturing apparatus of the present invention is used, particularly in the case of manufacturing an electrophoretic display device, when a gap between two substrates is very small, or when a flexible substrate or the like is used. Even in the case of using, the charged electrophoretic particles in the dispersion can be easily and uniformly arranged in each display element, and a high-quality electrophoretic display device can be manufactured. Further, since an electrode facing the device side is not required, mass productivity and manufacturing cost are extremely superior to those of the conventional device.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an example of an apparatus for manufacturing an electrophoretic display device according to the present invention.

FIG. 2 is an explanatory diagram showing the principle of a conventional electrophoretic display device.

FIG. 3 is an explanatory view showing the principle of a conventional apparatus for manufacturing an electrophoretic display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Manufacturing apparatus of electrophoretic display device 12 Charged electrophoretic particles 13 Dispersion medium 14 First container 15 Dispersion liquid 16 Second container 17 Stirring means 18 Substrate 19 Substrate holding means 110 Voltage applying means 111 First optical density detecting means 112 Second concentration detecting means 113 Control means 21, 22 Electrode 23 Positive charge electrophoretic particles 24 Insulating liquid 25 Electrophoretic display

Claims (6)

[Claims] 1. An apparatus for manufacturing an electrophoretic display device including at least charged electrophoretic particles, a dispersion medium in which the electrophoretic particles are dispersed, and a substrate on which electrodes are formed,
Storage means for storing a dispersion liquid in which the charged electrophoretic particles are dispersed; means for stirring the dispersion liquid; substrate holding means for holding a substrate in the dispersion liquid; and a voltage applied to an electrode formed on the substrate. And a device for applying charged particles to deposit charged electrophoretic particles on the electrodes. 2. The apparatus for manufacturing an electrophoretic display device according to claim 1, wherein said manufacturing apparatus has storage means for two or more dispersion liquids having different concentrations of charged electrophoretic particles. 3. An apparatus for manufacturing an electrophoretic display device according to claim 1, wherein said substrate holding means has a function of transporting the substrate and a mechanism for swinging and rotating the substrate. 4. The apparatus for manufacturing an electrophoretic display device according to claim 1, wherein said manufacturing apparatus further comprises a means for measuring the concentration of a dispersion in which charged electrophoretic particles are dispersed. 5. The apparatus for manufacturing an electrophoretic display device according to claim 1, wherein said manufacturing apparatus further comprises means for measuring the concentration of charged electrophoretic particles collected on a substrate. 6. The apparatus for manufacturing an electrophoretic display device according to claim 1, wherein the means for applying a voltage to the electrodes is continuously performed while switching the polarity between positive and negative.