JP2003248243A - Image display manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent particles from splashing in manufacturing a dry type image display and retain sufficient initial charge quantity on the particles. <P>SOLUTION: In an image display, particles 3, 4 are sealed between two opposed substrates 1, 2 at least one of which has light transmissivity, the particles 3, 4 consist of two or more kinds of particles having different color and are formed in groups of two kinds, the two kinds of each group have different triboelectrification characteristics, an electrostatic field is provided to the particles 3, 4 from an electrode pair provided between the two substrates, and the two kinds of particles 3, 4 of each group are made to fly and move by Coulomb force to display an image. In manufacturing the image display, at least the one substrate of the two substrates 1, 2 is coated with the two kinds of particles 3, 4 of each group by the electrostatic powder coating method and the particles 3, 4 are then sealed between the two substrates 1, 2. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an image display device, and more particularly, to a reversible image display device (image display medium) capable of repeatedly displaying an image by utilizing flight movement of particles due to Coulomb force. ) Related to the manufacturing method.

[0002] In recent years, with the increase of environmental awareness such as making a paper palace, a research on an electronic paper display that can display a desired image on a display substrate by using electric force and can be rewritten is also being conducted. Has been done a lot. Especially famous for this electronic paper technology is
Liquid phase types such as an electrophoretic type and a thermal rewritable type (for example, see Non-Patent Document 1). However, in the liquid phase type, particles migrate in the liquid, so that the response speed becomes slow due to the viscous resistance of the liquid. Due to problems, a dry type having a structure in which insulating color particles are enclosed between opposed substrates as shown in FIG. 3 has recently been attracting attention.

[0003]

[Non-Patent Document 1] Zhao, 3 foreigners, "New Toner Display Device (I)", July 21, 1999,
Annual Meeting of the Imaging Society of Japan (83 times in total) “Japan Hardcop
y'99 ”, p.249-252

[0004]

However, the manufacturing method for the dry type is not generally established,
A method of uniformly and evenly and smoothly enclosing particles (groups), which is a particularly important point, between substrates has hardly been constructed. Here, if the encapsulation of particles does not satisfy the above conditions, problems such as color unevenness, image defects, unevenness in image response speed due to nonuniform substrate gap, and increase in drive voltage occur.

Examples of the method for enclosing the particles between the substrates include, for example, a roll coater coating method in which the powder is stretched over the substrate, and the powder is suspended in the air by stirring, air blowing, or the like, and passes through the substrate. Although a particle dipping method or the like in which the particles are applied onto the substrate by such a method is conceivable, in the roll coater application method, since the particles are difficult to adhere to the substrate, insufficient filling amount (application amount) and uneven concentration occur. In addition, in addition to the particle dipping method, the particles are less likely to adhere to the substrate, so that the filling amount is likely to be insufficient, and in addition,
2 because the particles are not so firmly fixed to the substrate
Neither method is sufficient, because shocks when stacking the substrates and scattering or displacement of laminated particles due to wind pressure are likely to occur.

From the above, it is an object of the present invention to provide a method of manufacturing an image display device capable of uniformly and evenly and smoothly enclosing two or more kinds of powder between opposed substrates.
More specifically, the powder is evenly and evenly coated on one or both substrates, and even when the two substrates are superposed, the particles are not scattered or the powder layer is displaced. An object is to provide a method for manufacturing an image display device.

[0007]

According to the method of manufacturing an image display device of the present invention which achieves the above-mentioned object, at least one of the two facing each other is colored between two substrates having a light transmitting property. 2 or more types of particles with different
An electric field is applied from the electrode pair provided between the two substrates to the particles, each of which has a different triboelectrification characteristic from each other.
When manufacturing an image display device for flying and moving particles of two kinds to display an image, two kinds of particles of each set are applied onto at least one of the two substrates by an electrostatic powder coating method. It is characterized in that it is sealed between the two substrates after coating.

According to the method of manufacturing an image display device of the present invention, since an electrostatic adhesion force is generated between the particles as powder and the substrate by the electrostatic powder coating method, a desired amount is obtained. Particles can be uniformly coated on the substrate, and since the particle layer is fixed by the electric image force between the substrate and the substrate after coating, there is no scattering or deviation of the particles when the substrates are stacked. Can be prevented.

Here, the electrostatic powder coating method is a coating method in which a solid powder coating material is attached to the surface of an object to be coated by using static electricity. According to this coating method, the object to be coated is A uniform and dense powder coating layer can be formed on the surface by electric image force. The electrostatic powder coating method is an electrostatic spray method in which powder coating material is charged and discharged from an electrostatic spray gun, and is caused to fly by air force and electric field force to adhere to an object by electric image force. And air is blown from the bottom plate of the perforated plate provided with the electrodes to form a fluidized bed of the powder coating material and a floating layer of charged powder particles above the fluidized bed in the fluidized tank. There is an electrostatic fluidized dipping method in which a powder coating material is adhered by an electric image force through a coating material. And the electrostatic spray method,
Corona charging method that charges the powder discharged from the electrostatic spray gun with the corona generated at the tip of the spray gun, and charges the powder discharged from the electrostatic spray gun by friction with the electrode inside the spray gun. There is a tribo charging method that allows the charging, and a hybrid charging method that combines them.

In the method of manufacturing an image display device of the present invention, the particles are coated on the substrate instead of the powder coating material by the electrostatic powder coating method. Any of the above methods may be used.

The above two or more kinds of particles may be mixed and applied, but since the triboelectric charging characteristics of the two kinds of particles of each set are different, when they are combined, the polarities are opposite to each other. Since there is a possibility of coagulation due to Coulomb force before, it is preferable to apply two kinds of particles of each set one by one. The two or more kinds of particles may be applied to only one of the two substrates or both of them. First, the two or more kinds of particles are applied to only one of the two substrates. Is preferred, and then the substrate is superposed on the other substrate on which no particles are applied to encapsulate the particles, which is preferable because the manufacturing process can be facilitated.

Preferably, when the two or more types of particles are coated on one of the two substrates by the electrostatic powder coating method, the polarities of the electric charges of the two or more types of particles are set. Make them the same.

For example, when two kinds of powders are laminated on a substrate by electrostatic powder coating, one kind of powder is positively charged and the other kind of powder is negatively charged to a negative electrode. However, if lamination is carried out by this method, coulombs between particles cause agglomeration of the powder, resulting in loss of uniform distribution and smoothness. Therefore, it is preferable that two or more kinds of powders are applied to the same substrate by electrostatic powder coating, and all the powders are charged with the same polarity when they are laminated.

It is preferable that the potential applied to the particles to be applied first is lower than the potential applied to the particles to be applied next and laminated on the layer of the particles applied first.

This is because when the charge amount of the particles in the first layer is too large, the electric image force between the particles in the substrate and the surface of the substrate becomes too strong, and the adhesive force is strong even when an electric field is applied to the particles in the first layer. This is because the particles may not move from the surface of the substrate due to the excess of the particles. On the other hand, for the next layer, the first layer already exists, so even if the charge amount during coating is large, Adhesion does not become too strong, on the contrary, if the amount of charge during coating is small, the adhesion to the substrate surface is too weak, and when the other substrate is piled up, scattering of particles and deviation of the particle layer occur. This is because it tends to occur.

However, when the lamination is carried out by the above-mentioned method, there are cases where cohesion and repulsion of particles occur due to interaction such as Coulomb force and intermolecular force between particles, resulting in loss of uniformity and smoothness. In such a case, the two types of particles of each set are applied to the two substrates by electrostatic powder coating, one type for each substrate, and the above-mentioned process is performed at the time of the application. The potential applied to the particles is preferably 40 KV or less. By doing so, in addition to preventing the particles from agglomerating and repulsing, even if the electric image force between the surface of the substrate and the particles becomes too strong due to the excessive charge of the particles, an electric field is applied to the particles. It can also prevent particles from becoming stuck on the substrate surface.

In the method for manufacturing an image display device of the present invention, a spacer for leaving a predetermined gap between the two substrates is held on at least one of the two substrates. preferable. With this configuration, it is possible to easily secure a predetermined gap between the two substrates.

Further, in the method for manufacturing an image display device of the present invention, it is preferable that a partition wall for partitioning cells of the cell group is provided on at least one of the two substrates. In this way, it is possible to easily secure a partition wall for partitioning the cells of the cell group between the two substrates.

Further, in the method for manufacturing an image display device of the present invention, the average particle diameter of the particles is 0.1 μm or more and 5
The thickness is preferably 0 μm or less, and it is preferable that the electrodes forming the electrode pair are provided on the inner surfaces of the two substrates so as to face each other, and at least one of the two substrates is a transparent electrode glass. Alternatively, it is preferably formed of a transparent electrode resin, and further, it is preferable that encapsulation of the particles between the two substrates is performed in an environment of a relative humidity of 60% RH or less.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a method for manufacturing an image display device of the present invention will be described in detail below. In the embodiment described below, two types of particles having different colors and triboelectrification characteristics, for example, white particles 3 having positive triboelectrification characteristics and negative triboelectrification characteristics are provided between two substrates 1 and 2 as shown in FIG. And the black particles 4 having particles are divided into a plurality of cells in a matrix array by a lattice-like spacer 5 having a height of 50 μm which also functions as a partition wall interposed between the substrates, and each cell has two types of particles 3, 4 The present invention is not limited to this embodiment, though it is a method for manufacturing a dry image display device D in which a predetermined gap is provided between the substrates 1 and 2 with the spacer 5 provided therein. Not something.

In this embodiment, a transparent substrate 1 as two substrates and a counter substrate 2 are both provided on a glass substrate.
A conductive transparent glass substrate having TO (indium tin oxide) vapor-deposited thereon was used, and a spacer 5 which also functions as a partition wall for a plurality of cells was provided by an inkjet method on only one substrate 2. Further, as the white particles 3 having a positive frictional charging property, titanium oxide is used as a white pigment and a quaternary ammonium salt compound is used as a charge control agent, and polymerized particles of styrene acrylic resin (spherical particles having an average particle size of 8 μm). As black particles 4 having negative triboelectrification characteristics, black polymerized toner for electrophotography (average particle size 8
μm spherical particles) were used. Then, white particles 3 having positive triboelectric charging characteristics and black particles 4 having negative triboelectric charging characteristics.
When and were laminated on a substrate and sealed between the substrates, specifically, it was performed as in each of the following examples.

[0022]

In EXAMPLE examples to coated particles on a substrate using a such corona-type electrostatic powder coating apparatus shown in FIG. 2, the coating method, the one, the substrate of direction without spacers 5 Only 1 was coated with white particles 3 and black particles 4 in this order.
In the figure, reference numeral 6 is a corona electrostatic spray gun, 7 is a conductive plate that is grounded and supports the substrate, 8 is a device for supplying particles as powder, and 9 is a power source. That is, in Example 1, as shown in FIG. 2, a corona electrostatic spray gun 6 was used to apply a corona voltage of −30 kV to the white particles 3 to form a layer of the first white particles 3 on the substrate 1. After coating, a corona voltage of −60 kV was applied to the black particles 4 to stack a second layer of the black particles 4 on the first layer.

By superposing the other substrate 2 provided with the spacer 5 on the substrate 1 on which the particle layers are laminated and fixing the adhesive surfaces of the two substrates 1 and 2 with resin from the sides, It was possible to manufacture the image display device D in which the two types of particles 3 and 4 were enclosed. This image display device D has a voltage of 10
When an alternating voltage of 0 V and a frequency of 2 Hz was applied to produce a reverse image on the entire surface, a clear reverse image without unevenness was confirmed after 3 seconds.

[0024]

As is apparent from the above description, according to the method of manufacturing an image display device of the present invention, an electrostatic adhesion force is generated between the particles and the substrate by the electrostatic powder coating method. Since the desired amount of particles can be evenly coated on the substrate, and the layer of the particles is fixed by the electric image force between the substrate and the substrate after coating, when the substrates are superposed. It is possible to prevent scattering and deviation of particles.

According to the method of manufacturing the image display device of the present invention, the two different colors are formed by the electrostatic powder coating method.
Of the two types of particles of each set of two or more types of particles, positive electric charge is applied to positive triboelectrically charged particles and negative charge is applied to negative triboelectrically charged particles. After coating on at least one of the substrates, the particles are sealed between the two substrates, so that the particles can retain a sufficient initial charge amount.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a dry image display device manufactured by an embodiment of a method for manufacturing an image display device of the present invention.

FIG. 2 is an explanatory diagram showing an example of an electrostatic powder coating method used in the manufacturing method of the above embodiment.

FIG. 3 is an explanatory diagram illustrating a conventionally known dry image display device.

[Explanation of symbols]

1 transparent substrate 2 Counter substrate 3 white particles 4 Black particles 5 spacers 6 Corona type electrostatic spray gun 7 Conductive plate 8 Particle feeder 9 power supplies

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yakushiji Manabu             3-2-6 Ogawahigashi-cho, Kodaira-shi, Tokyo (72) Inventor Koji Takagi             3-21-33-, Miyauchi, Nakahara-ku, Kawasaki-shi, Kanagawa             304 (72) Inventor Yoshitomo Masuda             3-5-28 Shinmeidai, Hamura-shi, Tokyo (72) Inventor Takahiro Kawagoe             1302-57 Aobadai, Tokorozawa, Saitama Prefecture

Claims (9)

[Claims] 1. Particles of two or more kinds having different colors, which are enclosed between two substrates having at least one facing each other and having a light-transmitting property, and are made into groups of two kinds, and An electric field is applied to the particles of which two types have different triboelectrification characteristics from an electrode pair provided between the two substrates to fly and move the two types of particles of each set to display an image. In manufacturing the image display device, the two types of particles of each set are applied on at least one of the two substrates by an electrostatic powder coating method, and then the two types of particles are applied between the two substrates. A method for manufacturing an image display device, characterized in that 2. When the two or more types of particles are coated on one of the two substrates by the electrostatic powder coating method, the two or more types of particles have the same charge polarity. The method of manufacturing an image display device according to claim 1, wherein 3. The potential applied to the particles to be applied first is
3. The method of manufacturing an image display device according to claim 2, wherein the potential is lower than the potential applied to the particles to be applied next and laminated on the layer of the particles applied first. 4. The spacer according to claim 1, further comprising a spacer for holding a predetermined gap between the two substrates, the spacer being held on at least one of the two substrates. The method for manufacturing the image display device according to any one of the above. 5. The image according to claim 1, wherein a partition wall for partitioning cells of the cell group is provided on at least one of the two substrates. Manufacturing method of display device. 6. The average particle size of the particles is set to 0.1 μm or more and 50 μm or less, according to any one of claims 1 to 5.
The method for manufacturing an image display device according to any one of 1 to 3 above. 7. The manufacturing of an image display device according to claim 1, wherein electrodes forming the electrode pair are provided on the inner surfaces of the two substrates so as to face each other. Method. 8. The image display device according to claim 1, wherein at least one of the two substrates is made of transparent electrode glass or transparent electrode resin. Method. 9. The image display device according to claim 1, wherein encapsulation of the particles between the two substrates is performed in an environment of a relative humidity of 60% RH or less. Manufacturing method.