JP2003202604A - Electrophoretic display device and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophoretic display device with a simple matrix driving structure, of which the electrophoretic display cell structure is simplified, the production cost is reduced with the aid of a simple process and the accuracy of aligning positions of the cells and driving electrodes is improved. <P>SOLUTION: The electrophoretic display device is provided with a unit pixel which has first electrodes with strip shapes, second electrodes with strip shapes placed on both sides of the first electrodes in parallel with the first electrodes, regions between electrodes with chemical affinities different from those of the first and second electrodes and held between them, a plurality of microcapsules containing a dispersion liquid with a plurality of electrophoretic particles dispersed in an insulating liquid, having shells with a chemical affinity closer to the chemical affinity of the regions between electrodes than to that of the first and second electrodes and aligned on the surfaces of the regions between electrodes and third electrodes extending in a direction intersecting with the first electrodes on the upper side of a plurality of the microcapsules. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electrophoretic display device and a manufacturing method thereof.

[0002]

2. Description of the Related Art Expectations for a reflective display device have been increasing from the viewpoint of reducing power consumption or reducing the burden on the eyes. An electrophoretic display device described in, for example, U.S. Pat. No. 3,668,106 is known as one of the reflective display devices. This electrophoretic display device
A dispersion composed of electrophoretic particles having an electric charge and an insulating liquid, and a pair of electrodes facing each other with the dispersion interposed therebetween,
By applying an electric field to the dispersion liquid via this electrode, the electrophoretic particles are moved to an electrode having a polarity opposite to that of the electric charge to perform display.

The contrasting color of the electrophoretic particles is carried by the above-mentioned insulating liquid in which the dye is dissolved. More specifically, if the electrophoretic particles adhere to the surface of the first electrode close to the observer, the color of the electrophoretic particles is observed, while the electrophoretic particles are on the surface of the second electrode far from the observer. When adhered to, the color of the electrophoretic particles is hidden by the insulating liquid and the color of the insulating liquid is observed.

The electrophoretic display device is, for example, a procedure. of. The. SID (Proc.SID), 1
8, 267 (1977), it has the advantages of wide viewing angle, high contrast and low power consumption, but there is no threshold characteristic between the applied voltage and the display color characteristic. Therefore, each pixel electrode must have a switching element. Standard thin film transistor (TFT) technology used in liquid crystal displays is not applicable due to the high applied voltage required and the high cost due to the complicated process in a clean environment similar to semiconductor manufacturing. Have difficulty. In addition, when a circuit for a switching element of each pixel is separately provided and wired to each pixel electrode, the number of wires becomes large and complicated in an application where the number of pixels is large,
Realization becomes extremely difficult.

To solve this problem, Japanese Patent Laid-Open No. 2001-201
As disclosed in Japanese Patent No. 770, there is an example in which a simple matrix drive is enabled by devising a cell structure.
This electrophoretic display device holds a dispersion liquid composed of electrophoretic particles having a charge and an insulating liquid between a first substrate having three types of electrodes and a second substrate having one type of electrodes. It has a structure. Further, there is a partition wall for providing the control electrode in the cell.

[0006]

As described above, the electrophoretic display device having a high resolution and a large number of pixels has a problem in the pixel driving method. On the other hand, in the simple matrix driving in which the cell structure is devised. Attempts have been made.

In this simple matrix driving, there are many kinds of electrodes, and the shapes of these electrodes are complicated. Also, regarding the shape of the cell that constitutes each pixel, the cell structure is complicated, for example, by processing such as providing a step on the surface of the substrate and providing a partition wall for providing a control electrode in the cell. The complicated electrode or cell structure leads to an increase in the manufacturing cost of the display device without utilizing the features of the simple electrophoretic display device. Further, there is a problem that the partition walls existing in the cell prevent high resolution. Even if the resolution of the display device becomes higher and the cell becomes smaller, the size of the partition wall cannot be made smaller than this, and as a result, the aperture ratio is lowered and the display characteristics are deteriorated.

The present invention has been made in order to solve the above-mentioned problems of the simple matrix driving technique of the conventional electrophoretic display device, and its purpose is to simplify the electrophoretic display cell structure. An object of the present invention is to provide an electrophoretic display device having a simple matrix drive structure in which the manufacturing cost is suppressed by a simple process and the positional accuracy of the arrangement of cells and drive electrodes is improved.

[0009]

In order to achieve the above object, the features of the present invention are: (a) a strip-shaped first electrode;
(B) a strip-shaped second electrode arranged parallel to the first electrode on both sides of the first electrode, and (c) a chemical affinity different from those of the first and second electrodes, The interelectrode region sandwiched between the first electrode and the second electrode and (d) the dispersion liquid in which a plurality of electrophoretic particles are dispersed in the insulating liquid are included, and the chemical affinity of the first and second electrodes is included. A plurality of microcapsules arranged on the surface of the inter-electrode region, having a shell having a chemical affinity closer to that of the inter-electrode region than the conductivity, and (e)
A gist of the present invention is to provide an electrophoretic display device including a unit pixel having a plurality of microcapsules and a third electrode running in a direction intersecting the first electrode.

According to a feature of the present invention, an electrophoretic display having a simple matrix driving structure in which the electrophoretic display cell structure is simplified, the manufacturing cost is suppressed by a simple process, and the positional accuracy of the arrangement of the cells and the driving electrodes is improved. A device can be provided.

In the feature of the present invention, the chemical affinity of the microcapsules is preferably hydrophilic. The chemical affinity indicates whether certain substances are chemically easy to stick to each other or hard to stick to each other chemically. It is well known that water or oil has an affinity, and those that are compatible with water are called hydrophilic or aqueous, and those that repel water are hydrophobic or oily. The “material C having an affinity closer to the chemical affinity of the material B than the chemical affinity of the material A” means that the material C has a characteristic of being more likely to stick to the material B than the material A. Specifically, when the chemical affinity is the degree of hydrophilicity, when the contact angles of the materials A, B, and C with respect to pure water are measured, the contact angle of the material B is higher than the contact angle of the material A. Refers to material C with a contact angle close to the corner.

[0012] Generally, an oily solvent exhibits high insulating properties. Therefore, an oily solvent is preferable as the insulating liquid, and when the oily dispersion is microencapsulated, it is carried out in an aqueous solution, and the water-soluble substance becomes the shell of the microcapsule.

In the feature of the present invention, it is preferable to provide a strip-shaped insulating film layer having a chemical affinity different from that of the microcapsule, the strip-shaped insulating film layer being disposed so as to intersect with the first electrode and the second electrode on the same plane. . In addition to the hydrophilic inter-electrode area for the hydrophilic microcapsules, the strip-shaped hydrophobic insulating films are arranged so as to intersect with each other, whereby the microcapsules can be accurately arranged two-dimensionally. Become.

Another feature of the present invention relates to (a) a strip-shaped first electrode having a chemical affinity different from that of the substrate surface on the substrate surface, and first electrodes on both sides of the first electrode. A step of forming two strip-shaped second electrodes in parallel,
(B) a step of forming an inter-electrode region sandwiched between the first electrode and the second electrode, having a chemical affinity different from that of the first electrode and the second electrode, and (c) an insulating liquid A plurality of microcapsules containing a dispersion liquid in which a plurality of electrophoretic particles are dispersed and having the same or similar shell of chemical affinity as the inter-electrode region sandwiched between the first electrode and the second electrode. A step of arranging the capsules on the surface of the inter-electrode region sandwiched between the first electrode and the second electrode; and (d) a third electrode running on the upper part of the microcapsule in a direction intersecting with the first electrode. A method for manufacturing an electrophoretic display device is characterized by including a step of forming.

According to another feature of the present invention, the electrophoretic display cell structure is simplified, the manufacturing cost is suppressed by a simple process, and the electric precision of the simple matrix drive structure in which the positional accuracy of the arrangement of the cells and the drive electrodes is improved. An electrophoretic display device can be provided.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, first and second embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic,
It should be noted that the relationship between the thickness and the plane dimension, the thickness ratio of each layer, and the like are different from the actual ones. Therefore,
Specific thicknesses and dimensions should be determined in consideration of the following description. Further, it is needless to say that the drawings include portions having different dimensional relationships and ratios.

(First Embodiment) The electrophoretic display device according to the first embodiment of the present invention is as shown in FIG.
Strip-shaped first electrodes 11 arranged on the first substrate 6
And strip-shaped second electrodes 12a and 12b arranged parallel to the first electrode 11 on both sides of the first electrode 11,
The first and second electrodes 11 and 12 have different chemical affinity, and the interelectrode regions 10a and 10b sandwiched between the first electrode 11 and the second electrodes 12a and 12b and the insulating liquid 1 A dispersion liquid 3 in which a plurality of electrophoretic particles 2 having charges of the same polarity are dispersed, and is the same as the inter-electrode regions 10a and 10b between the first electrode 11 and the second electrodes 12a and 12b. Alternatively, a plurality of microcapsules 5a and 5b having shells 4 having similar chemical affinity and arranged on the surface of the interelectrode regions 10a and 10b, and crossing the first electrode on top of the microcapsules 5a and 5b. The unit pixel is composed of the third electrode 13 that runs in the direction. The third electrode 13 is provided on the back surface of the second substrate 7 in FIG.

In the case of the electrophoretic display device having the structure shown in FIG. 1, the observer views the first substrate 6 from the outside of the second substrate 7.
To see the display device towards the second substrate 7 and the third substrate 7.
The electrodes of are transparent. On the first substrate 6, a coloring layer 8 having a contrasting color with the electrophoretic particles 2 and a base thin film 9 made of a hydrophilic material are sequentially arranged.

The power supply circuit 14 is for applying a voltage to the first electrode 11, the second electrodes 12a and 12b, and the third electrode 13, and determines the magnitude, polarity, sequence, etc. of the applied voltage. It can be set freely.

The first electrode 11 and the second electrode 12a, 1
2b consists of a hydrophobic material. Therefore, the microcapsules 5 having the shell 4 made of a hydrophilic material are arranged so as to be substantially on the centers of the surfaces of the hydrophilic interelectrode regions 10a and 10b.

FIG. 2 is a diagram schematically showing a planar configuration of the 2 × 2 pixel portion of the electrophoretic display device according to the first embodiment of the present invention as viewed from the second substrate 7 side. As shown in FIG. 2, the first electrodes 11a, 11b and the second electrodes 12a,
12b and 12c are alternately arranged at predetermined intervals in parallel in the vertical direction of the paper surface, and interelectrode regions 10a, 10 of the base thin film 9 separated by the first and second electrodes thereof.
b, 10c, and 10d are exposed and arranged. The microcapsules 5 have substantially the same size, and are arranged two-dimensionally so that the centers of the microcapsules 5 are substantially the centers of the surfaces of the underlying thin films 10a to 10d exposed in strips. A pixel 15 that is typically shown by being surrounded by a thick frame in FIG. 2 is composed of four 2 × 2 microcapsules 5a to 5d, and the microcapsules 5a and 5c are located on the inter-electrode region 10a and the microcapsule 5b. And 5d are arranged on the inter-electrode region 10b. Although illustration of other pixels is omitted,
Similarly, it is composed of four microcapsules 5. First
Of the third electrode 13a, 1b
3b is formed on the second substrate 7 and constitutes a matrix drive electrode. For example, in the pixel 15 shown in FIG. 2, the third electrode 13a is formed so as to cover most of all the constituent microcapsules 5a to 5d.

Generally, (n pixel columns) × (m pixel rows)
The electrode configuration in the electrophoretic display device of (1) is 2n + 1 pieces of first and second electrodes formed on the first substrate and m formed on the second substrate orthogonal to the first and second electrodes. It is composed of a third electrode of a book, and has a simple matrix structure with n first electrodes and m third electrodes.

Thus, the hydrophilic microcapsules 5
Are hydrophobic first and second, depending on their chemical affinity with each other.
Are easily arranged on the inter-electrode region of the hydrophilic base thin film 9 located between the electrodes.

FIG. 3 is a view of the entire electrode structure according to the first embodiment of the present invention as viewed from the second substrate 7 side.
5 can be arranged in an 8 × 8 matrix, but it goes without saying that the total number of pixels can be arbitrarily determined depending on the application. Also, here, the electrophoretic particles 2
Is used in black and the colored layer 8 is colored in white, but the combination color can be arbitrarily selected as long as it is a contrasting color or a color close to it.

The portion surrounded by a bold line in FIG. 3 in a square corresponds to one pixel. As described above, one pixel is 2 ×.
It is composed of four microcapsules 5 (see FIG. 2). The first electrode 11 and the third electrode 13 that intersect with each other to form a matrix drive electrode are each formed of eight lines corresponding to each pixel 15, and a screen rewriting signal is generated by the drivers 14a and 14c of the power supply circuit. Is applied. For the sake of explanation, for each pixel, the first to eighth pixel rows are arranged from left to right in FIG.
Pixel rows to eighth pixel rows. Each first electrode 11 is from left to right 11a to 11h, and each third electrode 13 is from top to bottom 13a to 13h. There are nine second electrodes 12, all of which are connected, and the same voltage is always applied by the driver 14b of the power supply circuit. And the first electrode 1
The magnitude of the signal voltage to the first, second electrode 12, and third electrode 13, and the time zone are controlled by the controller 14d of the power supply circuit.

The screen of the display device is sequentially rewritten from the first pixel row to the eighth pixel row. 4A and 4B show an example of a voltage application sequence to the first electrode 11 and the third electrode 13.

Prior to the rewriting of each pixel column, as an initialization operation, 0V is applied to all the first electrodes 11a to 11h, 15V is applied to all the third electrodes 13a to 13h, as shown at timing t _{S in} FIG. 15 V is applied to the second electrode 12. In this case, the electrophoretic particles 2 gather on the first electrodes 11a to 11h having the lowest potential. After initialization, the data will be rewritten according to the data to be displayed. Time zones T _{1 to} T _{8 in} FIG. 4 are timings at which the first to eighth pixel columns in FIG. 3 are rewritten in order from the left. FIG. 4A shows a voltage sequence of the first electrodes 11a to 11h corresponding to the first to eighth pixel columns in FIG. Further, FIG. 4B shows a voltage sequence to the third electrodes 13a to 13h corresponding to the first to eighth pixel rows. The electrophoretic particles 2 are held on the first electrodes 11a to 11h with the potential of the first electrodes 11a to 11h set to 0 V until each pixel column is rewritten.

First, the rewriting time period T _{1 of} the first pixel column
In, the voltage of the first electrode 11a is raised to 25V.
At this time, the voltage of the third electrode 13 is set to 0 V when displaying black and 30 V when displaying white. Figure 4
According to the voltage data 13a to 13h in (b), the first to eighth pixel rows of the first pixel column are rewritten as white-black -...- white. Then, when the rewriting is completed, the voltage value of the first electrode 11a is increased to 50V.

[0029] Similarly, the subsequently second to eighth pixel columns, in the corresponding time period _{T 2} to _{T 8,} the first electrode 11b through 11h, and the third electrode 13a to 13h,
A desired voltage is applied to each.

In the pixel of the pixel column whose display has been rewritten, the voltage of the first electrode is 50V, but the voltage of the third electrode is 0V because of the rewriting signal to the pixel of another pixel column. Alternatively, it may be 30 V, and the electrophoretic particles 2 may move from a desired position. For this reason, as shown in FIG. 4A, as the voltage applied to the third electrodes 13a to 13h, the same voltage 15V as that applied to the second electrode 12 is applied in the latter half of the time period for rewriting each pixel column. . In the first embodiment of the present invention, 0V or 30
The rewriting time for V is 10 ms, and the time for setting the intermediate voltage 15 V is 10 ms. By setting the intermediate voltage application time to the third electrode in the latter half of each rewriting time zone, the rewritten electrophoretic particles 2 are slightly moved in a direction different from the desired position in the first half of the rewriting time zone of other pixels. Although it moves, it can be returned to the desired position from the middle again during the application of the intermediate voltage in the latter half. In this way, in the rewritten pixel, the electrophoretic particles 2 reciprocate near the desired position in the rewriting time zone of another pixel column, but as a result, return to the desired position. .

As the final operation of rewriting the screen, the electrophoretic particles 2 are kept at a desired position by keeping the first electrode 11 at 50 V, the third electrode 13 at 15 V, and the second electrode 12 at 15 V for a certain period of time. Settle on the electrode of. In the first embodiment of the present invention, this holding time is 100 ms.

Even if the voltage of each electrode is set to 0 V after the rewriting, the electrophoretic particles 2 are formed as in the conventional electrophoretic display device.
Are held on the electrodes and it is possible to maintain their screen information.

The movement of the electrophoretic particles 2 is shown in FIGS.
Is shown using a cross-sectional view of the pixel 15. Figure 5
Initialization timing t_S, FIG. 6 shows the rewriting time period T₁No
To T ₈In the first half of Figure, Figure 7 shows other pixels after rewriting
Rewriting time zone, and FIG. 8 shows the rewriting time zone T₁Through
T₈Holding period T in the latter half of the period or in the final rewriting operation
_E, The stay position of the electrophoretic particle group 22 in each, and
The moving direction is shown.

The structure shown in FIGS. 5 to 8 is substantially the same as the structure described in FIG. 1, and hydrophilic microcapsules 5a and 5b containing the black electrophoretic particle group 22 therein.
Are arranged between the first substrate 6 and the second substrate 7.
A white colored layer 8 and a base thin film 9 made of a hydrophilic material are sequentially formed on the first substrate 6, and a first electrode 11 and second electrodes 12a, 12b made of a hydrophobic material are formed in a predetermined manner. It is formed on the base thin film 9 at intervals. A transparent third electrode 13 is provided on the second substrate 7 in a direction substantially orthogonal to the first electrode 11 and the second electrode 12.

As described above, the electrophoretic particles 2 having a positive charge are collectively collected on the first electrode 11 (0 V) having the lowest voltage at the timing t _S in FIG. As shown in FIG. 5, the electrophoretic particle groups 22 a and 22 b of the microcapsules 5 a and 5 b that form the pixel with the first electrode 11 interposed therebetween are unevenly distributed on the first electrode 11.
Electrophoretic particle population 22 until the rewriting time comes
a and 22b are held on the first electrode 11.

When a rewriting voltage of 25 V is applied to the first electrode 11 of the rewriting pixel column in the rewriting time period T _{1 to} T ₈ , the electrophoretic particle group 22 of the pixel column has the voltage of the third electrode 13 thereof. Follow to move. When the voltage applied to the third electrode 13 is 30 V, the electrophoretic particle groups 22a and 22b are separated from the first electrode 11 as shown in FIG.
The left and right second electrodes 12a and 1 having the lowest voltage of 15V
Head towards 2b respectively. When the voltage applied to the third electrode 13 is 0V, the electrophoretic particle groups 22a and 22b are the third electrode 1 above which the voltage is the lowest, as shown in FIG. 6B.
Head to 3. Then, while the electrophoretic particle population 22 is moving to a desired position, the potential of the first electrode 11 is raised to 50 V in the middle of the rewriting time zone, and the moving speed of the electrophoretic particle population 22 is accelerated.

In the pixel of the column where the rewriting is completed, the voltage of the first electrode 11 remains maintained at 50 V, but when rewriting the other pixel columns thereafter, the third electrode 13 is rewritten.
Voltage changes to 30V or 0V according to the rewrite data of other pixel columns. At that time, FIG. 7 (a) and (b)
As described above, the electrophoretic particle groups 22a and 22b are slightly moved from their desired positions. However, when the third electrode 13 reaches 15 V in the middle of the rewriting time zone of the other pixel column, the electrophoretic particle groups 22a and 22b are close to the desired positions as shown in FIGS. 8A and 8B, respectively. Return to.

A time period T after rewriting of all pixel columns is completed.
_E , 50 V for the first electrode 11 and 15 V for the third electrode 13
V and 15 V are applied to the second electrode 12 for a certain period of time to fix the electrophoretic particles 2 to desired positions. In white display, as shown in FIG.
2a and 22b gather on the second electrodes 12a and 12b which are the side wall bottoms of the macrocapsules 5a and 5b, respectively. On the other hand, in black display, as shown in FIG. 8B, the electrophoretic particle groups 22a and 22b are divided into macrocapsules 5a and 5b.
Collect along the upper third electrode 13 of each.

As described above, while the entire screen is being rewritten, the electrophoretic particle group 22 reciprocates between the desired position and the intermediate position, and settles at the desired position after the entire screen is rewritten. During rewriting, the electrophoretic particle group 22 is moving, so the image is not stable and becomes a blurry image, but the purpose is to display a still image such as an advertisement display board or electronic paper. It does not matter with a display device that does.

When the electrophoretic particle group 22 is collected on the second electrodes 12a and 12b, the observer can see the colored layer 8
As shown in FIG. 8A, the second electrode 12
The electrophoretic particle groups 22a and 22b on a and 12b are also visible, and the colored layer 8 and the electrophoretic particle groups 22a and 22b are also visible.
You will see a mixed color of gray. In order to prevent this, a shielding layer that shields the electrophoretic particle groups 22a and 22b on the second electrodes 12a and 12b may be provided on the surface of the second substrate 7.

According to the first embodiment of the present invention, a simple matrix drive in which the electrophoretic display cell structure is simplified, the manufacturing cost is suppressed by a simple process, and the positional accuracy of the arrangement of cells and drive electrodes is improved. An electrophoretic display device having a structure can be provided.

In the first embodiment of the present invention, the chemical affinity of the microcapsules 5 is preferably hydrophilic. The chemical affinity indicates whether certain substances are chemically easy to stick to each other or hard to stick to each other chemically. Well known is its affinity for water or oil,
Those that are compatible with water are called hydrophilic or water-based, while those that repel water are called hydrophobic or oil-based. Generally, oily solvents show high insulation. Therefore, an oily solvent is preferable as the insulating liquid 1, and when the oily dispersion liquid 3 is microencapsulated, it is carried out in an aqueous solution, and the water-soluble substance becomes the shell 4 of the microcapsule 5.

Next, a method of manufacturing the electrophoretic display device according to the first embodiment of the present invention will be described with reference to FIGS. The manufacturing method of the electrophoretic display device described below is an example, and it goes without saying that it can be realized by various manufacturing methods other than this, including this modification.

(A) As the first and second substrates 6 and 7, transparent glass plates with a thickness of 1 mm are used. First, the first substrate 6
Barium sulfate (BaSO ₄ ), calcium carbonate (CaCO ₃ ), silicon dioxide (Si
Fine powder such as O ₂ ) mixed with a fluororesin is spin-coated to a thickness of about 0.5 μm. On top of that, a transparent TiO ₂ layer having a hydrophilic property is formed to a thickness of about 0.1 μm.
To form a base thin film 9. Subsequently, ITO having a hydrophobic property is vapor-deposited to a thickness of about 0.5 μm and is etched to form the first electrode 11 and the first electrode 11 as shown in FIG. 9A.
Second electrodes arranged at equal intervals on both sides of the first electrode 11
The electrodes 12a and 12b are formed into strips. In this way, between the first electrode 11 and the second electrodes 12a and 12b, the exposed inter-electrode region 10 on the surface of the underlying thin film 9 is formed.
a and 10b are formed respectively. Further, as shown in FIG. 9B, the strip-shaped third electrode 13 is formed by vapor-depositing transparent ITO on the second substrate 7 to a thickness of about 0.1 μm and etching it. Here, the resolution of the display device is about 30.
0 dpi, the distance between the centers of the first and second electrodes is 4
0 μm and the microcapsule particle size are set to 40 μm.
As described above, the size in which two microcapsules are arranged vertically and two horizontally is one pixel.

(B) Next, the microcapsules 5 are prepared by the coacervation method. First, isoparaffin is used as the insulating liquid 1, and black resin toner (particle size 1 μm) is used as the electrophoretic particles 2, and both are mixed so that the mixing weight ratio of the electrophoretic particles 2 is 10%. Furthermore, in order to improve dispersion stability, a small amount of a surfactant is added to prepare Dispersion Liquid 3. In this case, the surface of the electrophoretic particle 2 is positively charged. Next, 13 parts by weight of the dispersion liquid 3 is added to pure water 10
Emulsify with 0 part by weight and 2 parts by weight of emulsifier with a homogenizer. This emulsified mixed solution was added to 5% gelatin at 40 ° C.
It is dropped into an aqueous solution of gum arabic so that the granular dispersion liquid 3 is dispersed in the aqueous solution. While stirring 10
% Acetic acid is added dropwise to adjust the pH to 3.5. By dropping acetic acid, gelatin reacts with gum arabic to form a polymer film on the surface of the granular dispersion liquid 3. After that, the temperature is lowered to 5 ° C., 37% formalin is added dropwise, and further 10
% NaOH aqueous solution was added dropwise to adjust the pH to 8.5, and the temperature was 50 ° C.
And the polymer film is cured. Then, it is washed with pure water and filtered with a 1 μm filter. Further classification is performed to obtain microcapsules 5 having an average particle size of 40 μm and a small particle size distribution, which are contained in the shell 4 made of a transparent polymer film having hydrophilicity.

(C) Next, water and water-soluble nylon as a binder resin are mixed with the microcapsules 5 prepared by the above method to form an ink. The microcapsule ink is printed on the first substrate 6 through a screen plate in which predetermined openings are two-dimensionally punched. Microcapsule 5
The shell 4 of which is hydrophilic, the first electrode 11 and the second electrode 12a,
Since 12b is hydrophobic and the inter-electrode regions 10a and 10b sandwiched by the first and second electrodes of the underlying thin film 9 are hydrophilic, the desired pattern shown in FIG. 10 is obtained according to the two-dimensional perforation pattern formed on the screen plate. At the position of microcapsule 5a,
5b can be arranged two-dimensionally.

(2) Next, as shown in FIG. 11, the second substrate 7 on which the above-mentioned third electrode 13 is formed is formed on the microcapsules 5 arranged on the first substrate 6 as desired. An electrophoretic display device panel is manufactured by adjusting and adhering it with a thermosetting resin or an ultraviolet curable resin so that the position becomes.

(Modification) FIG. 12 shows an electrophoretic display device according to a modification of the first embodiment of the present invention. By making the first and second electrodes 11 and 12 projecting, the placement accuracy of the microcapsules 5 can be physically improved. As shown in FIG. 12, the first electrodes 11a, 11b, 11c, ... And the second electrodes 11a, 11b, 11c, ... And the second electrodes 11a, 11b, 11c having a height of about 10 to 20 μm are formed by screen printing or gravure printing technology using conductive ink. Electrode 1
2a, 12b, ... Can be manufactured by printing on the first substrate 6. Such protrusion-shaped first and second
When the microcapsules 5 are printed on the substrate 6 having the electrodes, the effect of chemical affinity as well as the physical effect of the electrode shape is added. The microcapsule 5a is between the second electrode 11a and the first electrode 12a, the microcapsule 5b is between the second electrode 12a and the first electrode 11b, and so on. The first electrodes 11b and 11c and the second electrode 12
It is easily aligned between b. As described above, the microcapsules 5 can be arranged with higher accuracy by the simple manufacturing method.
Others are the same as those in the first embodiment of the present invention, and thus duplicated description will be omitted.

(Second Embodiment) FIG. 13 is a plan configuration diagram of an electrophoretic display device according to a second embodiment of the present invention. In the first embodiment of the present invention described above, in order to easily arrange the microcapsules 5, the microcapsules 5 are sandwiched by the hydrophobic first electrode 11 and the second electrode 12 on the first substrate 6. The inter-electrode region 10 of the hydrophilic underlying thin film 9 was formed. In the second embodiment, a hydrophobic insulating film 18 is provided in a direction substantially orthogonal to the first and second electrodes 11 and 12 and the interelectrode region 10 of the underlying thin film 9 sandwiched between these electrodes. This is different from the first embodiment described above. As shown in FIG. 13, the first electrodes 11a, 11b, 11c, ... And the second electrodes 12a, 12b are located at one end of the area where the microcapsules 5 are printed, that is, at the upper end of the paper in this example. 12c, ..., and interelectrode regions 10a, 1 of the underlying thin film sandwiched between these electrodes.
An insulating film 18 having a hydrophobic property is formed and arranged in a direction substantially orthogonal to 0b, ..., 10f ,.
Others are the same as those in the first embodiment, and thus redundant description will be omitted.

In the second embodiment, with respect to the hydrophilic microcapsule 5, the first electrodes 11a, 11b,
11c, the second electrodes 12a, 12b, 11c, and the insulating film 18 are hydrophobic, and the inter-electrode regions 10a, 10b, 10c sandwiched by the first and second electrodes of the base thin film 9 are hydrophilic, so that the screen The microcapsules 5 can be easily two-dimensionally arranged at a desired position according to the two-dimensional perforation pattern formed on the plate.

According to the feature of the second embodiment, the electrophoretic display cell structure is simplified, the manufacturing cost is suppressed by the simple process, and the positional accuracy of the arrangement of the cells and the drive electrodes is improved, and the simple matrix drive structure is provided. The electrophoretic display device can be provided.

A method of manufacturing the first substrate 6 of the electrophoretic display device according to the second embodiment will be described with reference to FIG.
Others are the same as the manufacturing method of the first embodiment,
The duplicate description is omitted. The manufacturing method of the electrophoretic display device described below is an example, and it goes without saying that it can be realized by various manufacturing methods other than this, including this modification.

(A) As the first substrate 6, a transparent glass plate having a thickness of 1 mm is used. First, on the first substrate 6, as a colored layer 8, a fine powder of barium sulfate (BaSO ₄ ), calcium carbonate (CaCO ₃ ), silicon dioxide (SiO ₂ ) or the like mixed with a fluororesin is spin-coated. It is formed to have a thickness of about 0.5 μm, and transparent TiO ₂ having a hydrophilic property is vapor-deposited thereon to a thickness of about 0.1 μm.
Subsequently, ITO having a hydrophobic property is vapor-deposited to a thickness of about 0.5 μm, and the first electrode 11a, 11b, 11c and the second electrode 12a, 12b are etched by etching as shown in FIG. 14 (a). , 12c are formed.

(B) Polyimide resin was formed by spin coating to a thickness of 5 μm, and was etched to obtain the structure shown in FIG.
As shown in (b), a hydrophobic insulating film 18 is formed and arranged at one end of the first substrate 6 in a direction substantially orthogonal to the first and second electrodes 11 and 12.

(C) Similar to the manufacturing method of the first embodiment, the microcapsule ink is printed on the first substrate 6 prepared by the above method through a screen plate having two-dimensionally predetermined openings. . The shell 4 of the microcapsule 5 is hydrophilic, the first electrodes 11a, 11b, 11c, the second electrodes 12a, 12b, 11c, and the insulating film 18 are hydrophobic, and the first and second electrodes of the underlying thin film 9 are Area 1 between the sandwiched electrodes
Since 0a, 10b, ..., 10f are hydrophilic, the microcapsules 5 can be easily two-dimensionally arranged at desired positions shown in FIG. 14C according to the two-dimensional perforation pattern formed on the screen plate. You can do it.

In the second embodiment, the hydrophobic insulating film 18 is formed over the first and second electrodes 11 and 12, but the hydrophobic insulating film 18 is the first insulating film. And the second
Even if it is under the electrodes 11 and 12 of the above, or at least partially in the interelectrode region 10 of the underlying thin film 9 sandwiched between the first and second electrodes 11 and 12, the same effect can be obtained. Is clear.

Further, in the second embodiment, the hydrophobic insulating film 18 is formed at one end of the region of the first substrate 6 on which the microcapsules 5 are printed. The hydrophobic first and second electrodes 11 at arbitrary positions inside the
12 and hydrophilic underlayer thin film 9 sandwiched between these electrodes
The same effect can be obtained by arranging in a direction orthogonal to the inter-electrode region 10.

Further, although the hydrophobic insulating film 18 is formed in a row on the first substrate 6 on which the microcapsules 5 are printed, it is sandwiched between the first and second electrodes 11 and 12, and these electrodes. A plurality of rows may be formed at a predetermined interval in a direction substantially orthogonal to the inter-electrode region of the base thin film 9. As shown in FIG. 15, the first electrodes 11 a, 11 b, 11 are formed on the first substrate 6.
c, the second electrodes 12a, 12b, 12c, and the interelectrode region 10 of the underlying thin film 9 sandwiched between these electrodes.
a, 10b, ..., 9f, and the first and second electrodes 1
1, 12 and a polyimide resin having a hydrophobic property is coated on the microcapsules 5 at intervals of four in a direction substantially orthogonal to the interelectrode region of the underlying thin film 9 sandwiched between these electrodes. Insulating films 18a and 18b are formed and arranged. Thus, the plurality of hydrophobic insulating films 18a, 18a
By forming b in the orthogonal direction, the microcapsule 5 can be accurately arranged and printed at a predetermined two-dimensional position. Here, the insulating film 18 is formed of 4 of the microcapsule 5.
Although it is formed for each piece, it goes without saying that the same effect can be obtained if a plurality of pieces are formed at a predetermined interval.

(Other Embodiments) As described above, the first and second embodiments of the present invention have been described. However, the description and drawings forming a part of this disclosure limit the present invention. Should not be understood to be. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

For example, if a hydrophilic material having a contrasting color is used as the first substrate 6, the colored layer 8 and the base thin film 9 need not be formed and can be omitted, and the colored layer 8 is made of a hydrophilic material. Needless to say, the underlying thin film 9 can be omitted.

In the first and second embodiments, the colored layer 8 plays a role of the contrasting color of the electrophoretic particles 2. However, as another method, the dye is dissolved in the insulating liquid 1. You may make it a contrasting color. In this case, the colored layer 8
Needless to say, can be omitted.

The microencapsulation technique described in the description of the first and second embodiments is the interfacial polymerization method.
In-situ polymerization method, in-liquid curing coating method, phase separation method from organic solution system, melting dispersion cooling method, air suspension method, spray drying method, etc. may be used, and application and form of display medium Needless to say, it can be appropriately selected according to the above.

Further, as the film of the microcapsule,
It has hydrophilic properties, and in addition to gelatin-arabic gum, condensation polymers such as melanin resin, epoxy resin, urea resin, phenol resin and furan resin, styrene-divinylbenzene copolymer, methyl methacrylate-
A thermosetting resin such as a three-dimensional crosslinked vinyl polymer such as a vinyl acrylate copolymer can be appropriately used.

Further, two or more kinds selected from the above-mentioned thermosetting resin and thermoplastic resin may be used to form a multilayer coating film forming the microcapsule. In this case, from the viewpoint of improving the thermal stability of the microcapsules, it is preferable to use a thermosetting resin for the outermost shell of the coating.

For the first and second electrodes, a material having hydrophobic characteristics was used to serve also as the first surface region. However, each electrode is formed of a hydrophilic material such as copper or aluminum. A material having a hydrophobic property may be coated thereon to form the hydrophobic first and second electrode surfaces.

As the insulating film material having a hydrophobic property, a fluorine resin, a dimethyl silicone resin, a sol-gel sintered film of alkoxysilane partially having a Si-alkyl group, an oxidized and baked film of cyclic perhydropolysilazane, etc. can be used. Titanium oxide can be used as a hydrophilic material that can be used as a base thin film material having hydrophilic properties, such as an oxidized and baked film of cyclic polymethylsilazane, a sol-gel sintered film of alkoxysilane, and a coating film of hydrophilic fine particle powder (eg, silica). In the case of using, a UV irradiation process may be appropriately added in order to improve the hydrophilic function. In addition, in the production of ink for microcapsules, a viscosity modifier, a surfactant, a dispersion stabilizer, a leveling agent, a defoaming agent, an antioxidant, etc. are used as an additive in addition to the binder resin, if necessary. Examples of polyvinyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, propylene triol, polytetramethylene glycol, and 1,4-butanediol can be used.

As described above, needless to say, the present invention includes various embodiments and the like not described here. Therefore, the technical scope of the present invention is defined only by the matters specifying the invention according to the scope of claims appropriate from the above description.

[0068]

According to the present invention, the electrophoretic display cell structure is simplified and the manufacturing cost is suppressed by the simple process.
It is possible to provide an electrophoretic display device having a simple matrix drive structure in which the positional accuracy of the arrangement of cells and drive electrodes is improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of an electrophoretic display device according to a first embodiment of the present invention.

FIG. 2 is a plan configuration diagram of the electrophoretic display device according to the first embodiment of the invention.

FIG. 3 is a diagram showing electrode relative positions of the electrophoretic display device according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating a voltage application sequence to electrodes of the electrophoretic display device according to the first embodiment of the present invention.

FIG. 5 is a diagram showing positions of electrophoretic particles in an initialization time zone (S) of a voltage application sequence of the electrophoretic display device according to the first embodiment of the invention.

FIG. 6 is a diagram illustrating movement of electrophoretic particles during a rewriting time period of (a) white and (b) black in a voltage application sequence of the electrophoretic display device according to the first embodiment of the present invention. is there.

FIG. 7 is a diagram showing (a) white and (b) black display microcapsules in a rewriting time zone for another pixel column in the voltage application sequence of the electrophoretic display device according to the first embodiment of the present invention. FIG. 6 is a diagram for explaining the movement of the electrophoretic particles.

FIG. 8 shows electrophoresis in microcapsules displaying (a) white and (b) black in a holding time period (E) of the voltage application sequence of the electrophoretic display device according to the first embodiment of the present invention. It is a figure explaining movement and a position of a particle.

FIG. 9 is a process sectional view explaining the manufacturing method of the electrophoretic display device according to the first embodiment of the invention.

FIG. 10 is a process sectional view explaining the manufacturing method of the electrophoretic display device according to the first embodiment of the invention.

FIG. 11 is a process sectional view explaining the manufacturing method of the electrophoretic display device according to the first embodiment of the invention.

FIG. 12 is a cross-sectional configuration diagram of an electrophoretic display device according to a modification of the first embodiment of the invention.

FIG. 13 is a plan configuration diagram of an electrophoretic display device according to a second embodiment of the invention.

FIG. 14 is a process sectional view explaining the manufacturing method of the electrophoretic display device according to the second embodiment of the invention.

FIG. 15 is a plan configuration diagram of an electrophoretic display device according to a second embodiment of the invention.

[Explanation of symbols]

1 Insulating liquid 2 Electrophoretic particles 3 dispersion 4 shells 5, 5a-5h Microcapsules 6 First substrate 7 Second substrate 8 colored layers 9 Underlayer thin film Area between electrodes 10a to 10f 11, 11a to 11h First electrode 12, 12a to 12c Second electrode 13, 13a to 13h Third electrode 14 power supply circuit 14a Power supply circuit driver for first electrode 14b Power supply circuit driver for second electrode 14c Power supply circuit driver for third electrode 14d Power supply circuit controller 15 pixels 18, 18a, 18b Insulating film 22, 22a, 22b Electrophoretic particle population

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Sadao Kajiura             1st Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa             Inside the Toshiba Research and Development Center (72) Inventor Yukio Kizaki             1st Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa             Inside the Toshiba Research and Development Center F-term (reference) 5C080 AA13 BB05 DD07 DD22 DD27                       DD28 JJ02 JJ04 JJ06

Claims (4)

[Claims] 1. A strip-shaped first electrode, a pair of strip-shaped second electrodes arranged in parallel to the first electrode on both sides of the first electrode, and the first and the second electrodes. Has a different chemical affinity than the second electrode,
An inter-electrode region sandwiched between the first electrode and the second electrode, and a dispersion liquid in which a plurality of electrophoretic particles are dispersed in an insulating liquid are included, and the chemical composition of the first and second electrodes is included. Affinity has a shell having a chemical affinity close to the chemical affinity of the inter-electrode region, a plurality of microcapsules arranged on the inter-electrode region surface, and on top of the microcapsules, An electrophoretic display device comprising: a unit pixel having a third electrode that travels in a direction intersecting with the first electrode. 2. The electrophoretic display device according to claim 1, wherein the chemical affinity of the microcapsules is hydrophilic. 3. A strip-shaped insulating film layer having a chemical affinity different from that of the microcapsules, the strip-shaped insulating film layer being disposed so as to intersect the first electrode and the second electrode on the same plane. The electrophoretic display device according to claim 1 or 2. 4. A strip-shaped first electrode having a chemical affinity different from that of the substrate on the surface of the substrate and a chemical affinity different from the substrate, and the first electrode having a chemical affinity different from that of the substrate on both sides of the first electrode. Forming a pair of strip-shaped second electrodes parallel to the first electrode, and having a chemical affinity different from those of the first and second electrodes,
A step of forming an inter-electrode region sandwiched between the first electrode and the second electrode; and including a dispersion liquid in which a plurality of electrophoretic particles are dispersed in an insulating liquid, the first electrode and the The inter-electrode region in which a plurality of microcapsules having the same or similar chemical affinity shell as the inter-electrode region between the second electrode and the second electrode is sandwiched between the first electrode and the second electrode A method of manufacturing an electrophoretic display device, comprising: a step of arranging on a surface; and a step of forming, on an upper portion of the microcapsule, a third electrode that runs in a direction intersecting with the first electrode. .