JPH0561075A - Electrophorectic display element - Google Patents

Abstract

PURPOSE:To obtain the electrophorectic display element which can decrease the generation of the discoloration, etc., of a dispersion by the flocculating and settling of electrophorectic particles and by UV rays, heat, etc., in plural block chambers and can maintain the appearance over the entire part. CONSTITUTION:This electrophorectic display element consists of a pair of substrates 1a, 1b, which are disposed to face each other and at least one of which are transparent, electrodes 2a, 2b which are respectively formed on the opposite surfaces 10a, 10b of a pair of the substrates 1a, 1b and at least either of which are transparent, and a light transparent dispersion medium 5 sealed into the sealing space S between a pair of the substrates 1a, 1b and the light shieldable electrophorectic particles 6 dispersed into the dispersion medium 5. The striped or meshed block members 3a, 3b for segmenting the sealing space S to the plural block chambers S1 are interposed in the sealing space S and at least the two adjacent block chambers S1 have a connecting passage 30 which is formed approximately in the middle between a pair of the substrates 1a and 1b and in which the dispersion medium 5 can move.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophoretic display device.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 59-34518 provides an electrophoretic panel which can maintain a uniform gap even when the display area is increased and does not cause uneven distribution or aggregation of pigments (electrophoretic particles). For this purpose, a transparent conductive film is provided on at least one side to form a dispersion system injection part between two opposing substrate films, and the dispersion system injection part is divided into a plurality of compartments by a partition body made of a non-conductive member. There is disclosed a configuration divided into.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
According to the configuration of the electrophoretic panel disclosed in Japanese Patent No. 518, it is possible to prevent the electrophoretic particles from aggregating and settling in the dispersion liquid in the entire display portion, and preventing the display performance from deteriorating. However, when discoloration of the dispersion liquid or the like occurs due to aggregation, sedimentation, or discoloration of the electrophoretic particles due to ultraviolet rays, heat, or the like, which occurs at a position close to the substrate of one of the plurality of compartments, The amount of transmitted light or the amount of reflected light in each compartment changes to cause uneven display of light and dark on the entire display portion (viewing side), which deteriorates the overall appearance.

According to the present invention, in the plurality of compartments, by agglomeration, sedimentation and ultraviolet rays or heat of the electrophoretic particles,
It is an object of the present invention to provide an electrophoretic display element capable of reducing discoloration of a dispersion liquid and maintaining the overall appearance.

[0005]

The electrophoretic display device of the present invention comprises a pair of substrates which are arranged to face each other and at least one of which is transparent, and at least one of which is formed on each of the surfaces of the pair of substrates which face each other. An electrophoretic display device comprising: a transparent electrode; a translucent dispersion medium enclosed in an enclosed space between the pair of substrates; and light-shielding electrophoretic particles dispersed in the dispersion medium. A striped or mesh partition member for partitioning the enclosed space into a plurality of compartments is interposed in the enclosed space, and at least two adjacent compartments are located approximately in the middle between the pair of substrates. It is characterized in that it has a connection passage formed and capable of moving the dispersion medium.

The most significant feature of the present invention is that the at least two adjacent compartments are formed substantially in the middle between a pair of substrates and have a connection passage through which a dispersion medium can move.
Thereby, in the dispersion liquid present in one of the plurality of compartments, even if the aggregation, sedimentation and ultraviolet rays of the electrophoretic particles, discoloration due to heat, etc. occur.
Dispersion liquids in other compartments in which such a phenomenon does not occur move to each other through the connection passages and are mixed with each other, so that the composition becomes a uniform composition as a whole and the above-mentioned problems can be reduced. For this reason,
The electrophoretic display element can prevent deterioration of appearance on the entire viewing side.

As the pair of substrates arranged so as to face each other, one in which both one and the other are transparent, or one in which one is transparent and the other is opaque can be used. As the transparent substrate, a transparent glass plate or a transparent resin flat plate can be used, and these may be slightly colored as long as they have translucency. The distance between the pair of substrates is about 50 to 150 μm. The pair of substrates can be used while being held horizontally or vertically.

At least one of the electrodes formed on the opposite surfaces of the pair of substrates is transparent, and when both of the pair of substrates are transparent, the electrodes should be transparent. Used. The transparent electrode is, for example, I
It can be formed using various transparent conductive materials such as TO (indium tin oxide) and tin dioxide. Further, the transparent electrode can be formed by using various conventionally known vacuum deposition methods, high frequency sputtering methods, spray methods, photoetching methods and the like.

In the following description, the case where a pair of substrates are held horizontally will be described. The partition member has a striped shape or a mesh shape and is interposed in the enclosed space to finely divide the enclosed space in the left-right direction or the front-back direction parallel to the pair of substrates to form a plurality of partitioned chambers. It has a connection passage that connects two adjacent compartments approximately in the middle between a pair of substrates.

This partition member can be installed in a plurality or in a single form. As the installation form composed of a plurality of the plates, for example, two plate-like ones each having a thickness of 40 to 70 μm and formed with through holes or recesses in a stripe shape or a mesh shape, in a direction in which the through holes or recesses face each other. The space of 10 to 20 μm serving as the connection passage may be maintained between the two, and the space may be installed on the opposing surface sides of the pair of substrates for use. In addition, as the installation form of the singular, for example, one end side concave portion and the other end which have a thickness of 80 to 150 μm and face each other with a space of 10 to 20 μm serving as the connection passage inside the center in the thickness direction thereof. It is possible to install and use a plate-shaped member having side recesses integrally formed.

The partition member may be made of a transparent material such as acrylic. The connection passage connects at least two adjacent compartments at approximately the middle between the pair of substrates, and is formed substantially parallel to the pair of substrates. The connection passage has a cross-sectional space and a cross-sectional shape that are large enough to move the dispersion medium existing in the middle of the compartment. The size of the cross-sectional space is, for example, 10 to 20 in the thickness direction of the partition member.
The size in the direction parallel to the substrate is preferably 10 to 30 μm. The cross-sectional shape is preferably square or rectangular, for example.

When the partition member has a stripe shape, it has a stripe hole. The stripe hole is formed by, for example, a frame-shaped peripheral wall portion that forms a partition member, and a plurality of vertical walls that have both ends connected to the peripheral wall portion and that are provided at regular intervals in the left-right direction or the front-back direction parallel to the substrate. .. this is,
A plurality of the enclosed spaces are divided only in the left-right direction or the front-back direction parallel to the substrate. Therefore, it is possible to form a plurality of compartments each having a hole having a wide opening and penetrating in the direction facing the substrate in the left-right direction or the front-back direction parallel to the substrate. The shape of the stripe hole may be, for example, a concentric circle when viewed from the viewing side of the element.

When the partition member has a mesh shape, it has a plurality of mesh holes and recesses. The mesh holes and the recesses are, for example, a frame-shaped peripheral wall portion that forms a partition member, and a plurality of vertical walls that are integrally connected to the peripheral wall portion and that are provided at regular intervals in the left-right direction and the front-back direction parallel to the substrate. In addition to the left-right direction, a plurality of enclosed spaces are also defined in the front-back direction. Therefore, when a mesh-shaped partition member is used, a larger number of partitioned chambers can be formed as compared with the case of a striped member. The shapes of the mesh holes and the recesses are, for example, circular when viewed from the front (visual) side of the element,
A rhombus, a rectangle (quadrangle, rectangle), a triangle, a hexagon, or the like can be used.

The light-transmitting dispersion medium is a non-conductive insulating medium, and may be transparent without coloring or may be slightly colored as long as it has a light-transmitting property. As the light-shielding electrophoretic particles, for example, particles having a color by themselves, such as pigments, or particles having their surfaces colored and coated with a coloring agent can be used. In addition, the electrophoretic particles, when the electrophoretic display element is not driven,
By switching variously between driving when a direct current is applied and driving when an alternating voltage is applied by an artificial operation, the light-shielding electrophoretic particles are naturally dispersed and moved and electrically in the transparent dispersion medium. Forcible dispersion movement is performed to block light transmission or reduce the amount of light transmission for dimming.

[0015]

In the electrophoretic display element of the present invention, at least two adjacent compartments partitioned by the partition member are
It has a connection passage formed almost in the middle between the pair of substrates, through which the dispersion medium can move. For this reason, for example, among a plurality of compartments, in the dispersion medium of one compartment, the electrophoretic particles are aggregated and settled at a position close to the substrate and partially affected by ultraviolet rays of the electrophoretic particles or heat. Even if there is a case where a phenomenon in which the amount of transmitted light or the amount of reflected light to the display portion (viewing side) of the element is different from that of other compartments is going to progress due to discoloration of The dispersion liquid in the other one of the compartments, which does not generate these, moves and mixes with each other by natural convection or forced dispersion with the application of a voltage through the connection passage, and thus the dispersion liquid in each compartment is dispersed. The dispersion state of the electrophoretic particles in the liquid medium and the brightness of the display portion (viewing side) of the element can be made uniform.

Therefore, in the electrophoretic display device divided into a plurality of compartments with the partition member interposed in the enclosed space, the original effect (aggregation and sedimentation of the electrophoretic particles in the dispersion medium is caused in one compartment). In addition to the effect of suppressing and preventing the generation of the entire enclosed space), the dispersion liquid of a plurality of compartments,
It is possible to move and mix with each other through the connection passage, it is possible to suppress the inconvenience that partially occurs in a part of the plurality of compartments, and the entire display portion (viewing side) of the element On the other hand, it is possible to reduce the unevenness of the bright and dark display and maintain a good appearance.

[0017]

【Example】

(Example 1) An electrophoretic display device of Example 1 will be described with reference to Figs. As shown in FIG. 1, the electrophoretic display device includes a first horizontally held pair of substrates.
Glass plate 1a and second glass plate 1b, first transparent electrode 1a and second transparent electrode 2b, mesh-shaped non-conductive first partition member 3a and second partition member 3b, spacer 4, dispersion medium 5 and electrophoretic particles 6.

First glass plate 1a and second glass plate 1b
Is made of a transparent soda-lime glass plate (made by Asahi Glass) having a thickness of 2.0 mm. First transparent electrode 2a and second
As shown in FIG. 1, the transparent electrodes 2b are the first electrodes facing each other.
Inner surface 10a of glass plate 1a and second glass plate 1b
The transparent ITO was vacuum-deposited by ion plating on the inner surface 10b of the to a thickness of about 1000Å.

First partition member 3a and second partition member 3b
Is an acrylic mesh-like one having a thickness t of 100 μm composed of the convex portions and the space portions of both partition members, and the mesh holes 32.
A and 32b have the same shape with a hole diameter L1 of 100 μm and a mesh line width L2 of 10 μm (see FIGS. 5 and 6). The first partition member 3a and the second partition member 3b are attached to the inner surface 10a of the first glass plate 1a and the inner surface of the second glass plate 1b with an adhesive (not shown) via the first transparent electrode 2a and the second transparent electrode 2b. It is adhered and fixed on the surface 10b. Then, as will be described later, the first glass plate 1a and the second glass plate 1b are interposed in the enclosed space S formed by the spacers 4 being interposed, and
The partition member 3a and the second partition member 3b are arranged at positions facing each other with a space h (see FIG. 6) of 10 μm serving as the connection passage 30. The plurality of mesh holes 32
The shapes of a and 32b are substantially square, as shown in FIG. 5, which is a partially enlarged view of the front surface (first glass plate 1a). The mesh holes 32a to be described as representatives are the right and left vertical wall portions 33 extending parallel to the left and right X directions of the first glass plate 1a shown in FIG. 1, and the first glass plate 1a at right angles to the left and right vertical wall portions 33. It is formed by the front and rear vertical wall portions 34 extending parallel to the front and rear Y direction, and penetrates in the vertical Z direction substantially parallel to the transmitted light R2.

As the dispersion medium 5, tetrafluorodiglomoethane (manufactured by Tokyo Kasei) having a specific gravity of 2.187 is used. As the electrophoretic particles 6, a red pigment (manufactured by Ciba Geigy) having a specific gravity of 1.46 was used. This is a particle whose surface is positively charged. Then, a dispersion liquid was prepared in which the concentration of the electrophoretic particles 6 was adjusted to 1% by weight and a slight amount of a dispersion stabilizing surfactant was added.

Then, on the peripheral edge of the inner surface 10a of the first glass plate 1a to which the first partition member 3a is adhered and fixed,
A spacer 4 (polyester manufactured by Toray) having a thickness of 100 μm is placed, and an epoxy adhesive (not shown) is applied around it. After that, the inner surface 10 of the second glass plate 1b to which the second partition member 3b is adhered and fixed is disposed at a position facing the inner surface 10a of the first glass plate 1a, and the epoxy adhesive is cured. Integrated with the first glass plate 1a.

The first glass plate 1a and the second glass plate 1
The first partition member 3a disposed in the enclosed space S between the first partition member 3a and
And the second partitioning member 3b, and each mesh hole 3
The plurality of compartments S1 formed by 2a and 32b and the connection passage 30 are filled with the dispersion liquid and filled with the dispersion liquid. Two types of power sources are connected to the first transparent electrode 2a and the second transparent electrode 2b. That is, the lead wires 71 and 72 that are provided with the DC power supply 7 and transmit the DC voltage are connected, and the lead wires 81 and 82 that are provided with the AC power supply 8 and are used to transmit the AC voltage are connected (FIG. 1). reference).

The electrophoretic display device of the present embodiment thus constructed has the first partition member 3a and the second partition member 3b.
The plurality of compartments S1 defined by and are the first glass plate 1
a and the second glass plate 1b at a substantially intermediate position, the connection passage 30
Are connected to each other by. Therefore, when the electrophoretic display element is not driven, the electrophoretic particles 6 in the dispersion medium 5 are dispersed.
, Even if one of the plurality of compartments S1 attempts to aggregate and settle, as shown in FIG.
The dispersion liquid consisting of the dispersion medium 5 and the electrophoretic particles 6 existing almost in the middle between the first glass plate 1a and the second glass plate 1b inside moves to each other through the connection passage 30 by natural convection and is mixed. By matching, the dispersion state of the electrophoretic particles 6 in the dispersion medium 5 in each compartment S1 can be made substantially uniform. Therefore, when the element is not driven, the brightness of the entire display portion (viewing side) of the element can be made uniform, and the appearance of the element can be favorably maintained without the uneven brightness display.

Here, the first transparent electrode 2a is a negative electrode,
When the second transparent electrode 2b is used as a positive electrode and switching is performed at the time of driving when a direct current voltage of DC100V is applied, as shown in FIG. 1, the electrophoretic particles 6 positively charged in the dispersion medium 5 are stored in the first partition member 3a. In each mesh hole 32a, the first transparent electrode 2a
Is attracted by the electric attraction force of and is rapidly moved to the position shown in FIG. As a result, the second glass plate 1
Incident light R1 incident from the b side is transparent to the second partition member 3
b becomes the transmitted light R2 that has passed through b and the first partition member 3a. Therefore, the brightness of the display portion (viewing side) of the element is darker than that in the non-driving state.

Therefore, the electrophoretic display element when driven by applying this DC voltage is in a uniform light-shielding state in each of the compartments S1 and can display darker than when not driven. Further, when the DC voltage is applied to the electrophoretic display element, or when the element is in a non-driving state for a long time (in one of the plurality of compartments S1, aggregation, sedimentation and sedimentation of the electrophoretic particles 6 occur). In the case where discoloration of the dispersion liquid occurs due to discoloration caused by ultraviolet rays or heat), switching is performed at the time of driving while applying an AC voltage. That is, when an AC voltage (sine wave voltage) of AC500V and a frequency of 500 Hz is applied to the first transparent electrode 2a and the second transparent electrode 2b, each electrophoretic particle 6 is moved by the action of the electric field.
As shown in (4), it moves into the dispersion medium 5 and is dispersed. In this case, the dispersive movement of the electrophoretic particles 6 in the dispersion medium 5 in each compartment S1 due to the electric action is accompanied by the movement of the dispersion medium 5.
The electrophoretic particles 6 and the dispersion medium 5 are connected to each other by the connection passage 3
It is possible to make the dispersion state of the electrophoretic particles 6 in the dispersion medium 5 in each of the partitioned chambers S1 uniform by moving into each of the partitioned chambers S1 through 0 and mixing with each other.

Therefore, the electrophoretic display element when an AC voltage is applied is in a light transmission state in which light is modulated by the light-shielding electrophoretic particles 6 substantially uniformly dispersed in the translucent dispersion medium 5 in each compartment S1. It is possible to make the brightness of the display portion (viewing side) of the element uniform and improve the appearance of the entire display portion (viewing side) of the element. As described above, according to the electrophoretic display element of Example 1, the electrophoretic particles 6 in the dispersion liquid medium 5 in one of the plurality of compartments when the electrophoretic display element is not driven are in contact with the first glass plate 1.
Even if the particles agglomerate and settle on the a side, the connection passage 30 is formed by natural convection or forced dispersion with application of an AC voltage.
It is possible to move and mix with each other through, and the above effect is obtained. In the electrophoretic display element of Example 1, the first glass plate 1 of one of the plurality of compartments S1 is used.
The case where the electrophoretic particles 6 aggregate and settle at a position close to the side a has been described. However, the discoloration of the dispersion medium 5 may occur due to discoloration of the electrophoretic particles 6 due to ultraviolet rays, heat, or the like. However, the same effect can be obtained.

The electrodes of the first transparent electrode 2a and the second transparent electrode 2b may be reversed and the electrophoretic particles 6 having opposite charges may be used. (Embodiment 2) The electrophoretic display element of Embodiment 2 shown in FIG. 7 is arranged in the enclosed space S between the first transparent electrode 2a and the second transparent electrode 2b to form a plurality of compartments S1. Example 1
In place of the first partitioning member 3a having the mesh holes 32a and the second partitioning member 3b having the mesh holes 32b, as shown in FIG. First partition member 3c including
Then, the configuration is the same as that of the first embodiment except that the second partitioning member 3d having the recess 32d is used.

The thicknesses of the bottom wall 320c of the recess 32c and the bottom wall 320d of the recess 32d are the same as those of the first transparent electrode 2.
a as a negative electrode and the second transparent electrode 2b as a positive electrode, DC100
When the DC voltage of V is applied and the switching is performed, the electrophoretic particles 6 positively charged in the dispersion medium 5 are recessed 32 c.
The value is such that it can be sucked by the electric attraction of the first transparent electrode 2a through the bottom wall 320c.

(Embodiment 3) The electrophoretic display device of Embodiment 3 shown in FIG. 9 has a first partition member 3c and a second partition member 3d which are formed separately from each other and have the same shape as in the second embodiment. 1 and 2 are arranged at opposite positions while holding a space h of 10 μm to be the connection passage 30,
As shown by 0, a plurality of hermetically sealed recesses 32e and a connection passage 3 that connects the recesses 32e at approximately the middle in the thickness direction.
The partition member 3e of the integrated type including the first transparent electrode 2a
The structure is the same as that of the second embodiment except that the space S between the first transparent electrode 2b and the second transparent electrode 2b is interposed.

[Brief description of drawings]

FIG. 1 shows that the electrophoretic display device of Example 1 is in a non-driving state, the dispersion mediums of a plurality of compartments are mixed with each other through a central passage by natural convection, and the electrophoretic particles are substantially uniform in the dispersion medium. Vertical cross-sectional view showing the case in a normal state dispersed in

FIG. 2 is a partially enlarged vertical cross-sectional view showing an enlarged state in which dispersion media are mixed with each other through a central passage and electrophoretic particles are prevented from aggregating and settling in FIG.

FIG. 3 is a view showing that the electrophoretic display device of Example 1 is in a driving state in which a DC voltage is applied, and electrophoretic particles are electrically adsorbed to the first transparent electrode of the first transparent substrate for each compartment. Longitudinal sectional view showing light condition

FIG. 4 is a vertical cross-sectional view showing a driving state in which an AC voltage is applied to the electrophoretic display element and the electrophoretic particles electrically repel and are dispersed in the dispersion medium liquid.

5 is a partially enlarged front view showing an enlarged part of the front surface of the first partition member in FIG.

6 is a sectional view taken along the line I-I in FIG.

FIG. 7 is a vertical cross-sectional view showing an electrophoretic display device of Example 2.

FIG. 8 is a vertical cross-sectional view showing a modified example 1 of the first partition member and the second partition member of the electrophoretic display element of Example 2.

FIG. 9 is a vertical sectional view showing an electrophoretic display device of Example 3.

FIG. 10 is a vertical cross-sectional view showing a partition member of the electrophoretic display device of Example 3.

[Explanation of symbols]

1a ... 1st glass plate 1b ... 2nd glass plate 2a ... 1st transparent electrode 2b ... 2nd transparent electrode 3a, 3c ... 1st partition member 3b, 3d ... 2nd partition member 3e ... Partition member 30 ... Connection passage S1 ... Compartment 33 ... Left and right vertical wall portions parallel to the first glass plate and the second glass plate 34 ... Front and rear vertical wall portions parallel to the first glass plate and the second glass plate 4 ... Space 5 ... Light-shielding electrophoretic particles 6 ... Translucent dispersion medium 7 ... DC power supply 8 ... AC power supply

Claims (1)

[Claims] 1. A pair of substrates, which are opposed to each other, at least one of which is transparent, at least one of electrodes, which is respectively formed on the opposite surfaces of the pair of substrates, are transparent, and an encapsulation between the pair of substrates. A translucent dispersion medium enclosed in a space and light-shielding electrophoretic particles dispersed in the dispersion medium;
In the electrophoretic display element, the enclosed space has a stripe-shaped or mesh-shaped partitioning member for partitioning the sealed space into a plurality of partitioned chambers,
An electrophoretic display device, characterized in that at least two adjacent compartments have a connection passage formed substantially in the middle between the pair of substrates and through which the dispersion medium can move.