JP2002014376A - Image display medium and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display medium and an image display device which can prevent defective display caused by bias of particles enclosed between substrates of the image display medium. SOLUTION: A spacer 26a consisting of a stimuli-sensitive polymer gel expandable and contractable by electric field is formed between a display substrate 20 and a back surface substrate 23. An electrode 21 for controlling a space is embedded respectively in a connecting surface of the spacer 26a and the display substrate 20, and a connecting surface of the spacer 26a and the back surface substrate 23. At the time of forming an image, a voltage control part 12 applies voltage to the electrode 21 for controlling a space to generate the electric field, and the space of the display substrate 20 and the back surface substrate 23 is widened by expanding the spacer 26a. At the time of displaying the image, application of the voltage is released to narrow the space of the display substrate 20 and the back surface substrate 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display medium and an image display apparatus, and more particularly to an image display medium that can be repeatedly rewritten and an image display apparatus that forms an image on the image display medium.

[0002]

2. Description of the Related Art Conventionally, as a rewriteable sheet-like display medium, Twisting Ball Disp has been known.
For example, a lay (two-color coated particle rotating display medium), an electrophoretic display medium, a magnetophoretic display medium, a thermal rewritable display medium, and a liquid crystal having memory properties have been proposed.

[0003] Among these repeatedly rewritable display media, a thermal rewritable display medium and a liquid crystal having a memory property are characterized by being excellent in an image memory property.

[0004] A display medium utilizing electrophoresis and magnetophoresis disperses colored particles movable by an electric field or a magnetic field in a white liquid, and forms an image with the color of the colored particles and the color of the white liquid. It is. For example, the image portion displays the color of the colored particles by attaching the colored particles to the display surface,
In the non-image portion, the colored particles are removed from the display surface, and white is displayed by the white liquid. In a display medium using electrophoresis and magnetophoresis, since the movement of the colored particles does not occur without the action of an electric field or a magnetic field, the display medium has a display memory property.

[0005] Also, Twisting Ball Dis
In the play, the spherical particles having the half surface painted white and the other surface painted black are reversely driven by the action of an electric field. For example, in the image portion, the black surface is on the display surface side, and in the non-image portion, the white surface is the display surface side. The display is performed by applying an electric field such that

According to this method, the particles do not undergo inversion driving unless there is an action of an electric field. Also, inside the display medium, oil exists only in the cavities around the particles, but since it is almost in a solid state,
It is relatively easy to make the display medium into a sheet.

However, a thermal rewritable display medium, a liquid crystal having a memory function, etc. cannot display a display surface of sufficient white like paper, and when an image is displayed, an image portion and a non-image portion are not displayed. Because the contrast is small,
It is difficult to provide a clear display.

In a display medium utilizing electrophoresis and magnetophoresis, white display is excellent with a white liquid, but when displaying the color of colored particles, the white liquid enters gaps between the colored particles. The concentration will drop. Therefore, the contrast between the image part and the non-image part becomes small, and it is difficult to obtain a clear display.

Further, since a white liquid is sealed in these display media, when the display medium is detached from the image display device and handled roughly like paper, the white liquid may leak from the display medium. There is.

[0010] Twist Ball Displa
In the case of y, even if the hemisphere painted white is completely aligned with the display side, the light rays entering the gap between the spheres are not reflected and are lost inside. Can not. Further, the white display becomes grayish due to the influence of light absorption and light scattering in the cavity portion. Further, it is difficult to completely invert the particles, which also causes a decrease in contrast, and as a result, it is difficult to obtain a clear display. Further, since the particle size is required to be smaller than the pixel size, fine particles having different colors must be manufactured for high-resolution display, which requires advanced manufacturing technology. There is also a problem.

For this reason, several display media using toner (particles) have been proposed as new display media for solving the above problems (Japan Har).
dccopy, '99 Transactions, p249-p252, Ja
Pan Hardcopy, '99 fall Preprints,
p10-p13).

These display media include a transparent display substrate,
Two types of particle groups (toners) having different colors and charging characteristics are sealed between the substrate and a rear substrate opposed with a small gap, and an electric field is applied between these substrates according to image information. By doing so, an image is displayed by attaching particles of any color to the display substrate.

According to the particle display medium using the particle group, the particle group does not move unless an electric field acts, so that the image display medium has a memory property. No liquid leakage problem. Since the display between white and black can be switched by 100% in principle, it is possible to display a clear image with high contrast. Further, a two-color image (for example, a black-and-white image) having a high display contrast can be displayed by using particles having a high concealing property. In the following, a display medium using a particle group is simply referred to as an image display medium.

[0014]

However, in the above-described image display medium, the particles between the substrates are biased depending on the orientation in which the image display medium is arranged, and a display defect occurs during repeated use of the image display medium. There is. This is remarkable especially when used vertically, since it is greatly affected by gravity.

In view of the above, it is an object of the present invention to provide an image display medium and an image display device which can prevent a display failure due to a bias of particles sealed between substrates of the image display medium.

[0016]

In order to achieve the above object, an image display medium according to the present invention is characterized in that at least a display side is transparent and a plurality of substrates arranged in a stack are provided. A pair of electrodes provided between substrates facing each other and generating an electric field in a space formed between the substrates by applying a voltage; and at least two types of electrodes sealed between the plurality of substrates and having different colors and charging characteristics. And a support means which is provided between each of the plurality of substrates arranged in a stack and which variably supports the distance between the substrates.

According to the image display medium of the present invention, at least two kinds of particle groups sealed between the substrates are moved to the display substrate side by an electric field formed between the substrates according to the image information. This is a configuration in which an image is displayed on the display substrate by a combination of the colors of the particles. Further, the image display medium of the present invention is provided with support means for variably supporting the distance between the substrates between the substrates. This makes it possible to increase or decrease the distance between the substrates according to the purpose.

In the present invention, the image display medium has two or more substrates stacked and arranged, and at least two types of particle groups are sealed between the substrates. Therefore, for example, when there are two substrates, an image is displayed by the color of the particles sealed in the space sandwiched between the two substrates. When there are three or more substrates, an image is displayed in each of at least two spaces sandwiched between the two substrates by a combination of colors of the encapsulated particles.

Preferably, as described in claim 2,
The support means is configured to widen the interval between the substrates when an electric field is generated between the substrates for writing an image. With this configuration, when the particles frequently move, the space between the substrates is widened, so that the movement of the particles becomes smooth, and the time between when the electric field is formed and when the image is formed on the display substrate is quickly increased. it can.

Further, the supporting means may have a structure in which, when an image is displayed after an image is formed, the distance between the substrates is narrowed so that the particles are difficult to move. With such a configuration, when the particles do not move frequently, the interval between the substrates is narrowed to a distance that makes it difficult for the particles to move. Therefore, the movement of the particles is hindered, and the particles do not easily peel off during image display. In particular, when the image display medium is placed vertically, the bias of particles due to gravity is prevented, and a stable image can be held for a long period of time.

As such a supporting means, for example, as described in claim 3, a spacer member made of a stimuli-responsive elastic material which expands and contracts by stimulation, and a stimulus applying means for applying a stimulus to the spacer member It can be configured to include. The stimulus described in the present invention is, for example, an electric, magnetic, light, temperature, chemical substance, or a factor that causes an environmental change such as pH. The stimulus-responsive stretchable material is provided with such a stimulus. It is a material that expands and contracts and recovers its original state when the stimulus is released.

Since the spacer member is made of a stimuli-responsive stretchable material that expands and contracts by stimulation, when a stimulus is applied from the stimulus applying means, the spacer member expands and contracts and changes the distance between a pair of substrates to be supported.

The spacer member may have a property of expanding when the stimulus is applied by the stimulus applying means, or may have a property of contracting or reducing when the stimulus is applied by the stimulus applying means. In the case of a spacer member having the property of expanding when a stimulus is applied, the stimulus applying means may be configured to apply a stimulus to the spacer member when writing and not to apply a stimulus when not writing. Further, in the case of a spacer member having the property of contracting when a stimulus is applied, the stimulus applying means may be configured so as to apply a stimulus to the spacer member during non-writing and not to apply a stimulus to the spacer member during writing.

The stimulus applying means may be configured to apply stimulus to the spacer member. The stimulus applying means may be integrated with the substrate or may be configured as a unit separate from the substrate.

According to a fourth aspect of the present invention, in the image display medium according to the third aspect, the stimulus-responsive stretchable material is an electric field-responsive material that expands and contracts when an electric field is applied. May be configured to control the state of application of an electric field applied to the spacer member to change the distance between the substrates.

By using an electric field responsive material as the stimulus responsive stretching material, for example, when forming an image display electrode on a substrate of an image display medium by lithography or etching, the electrode for the spacer member is also used. Since it can be formed at the same time, it is preferable from the viewpoint of manufacturing efficiency. In addition, by using a voltage, it is also possible to adopt a configuration in which a voltage applying unit for image formation and a stimulating unit are also used. There is also an effect.

According to a fifth aspect of the present invention, in the image display medium according to the third aspect, the stimulus-responsive stretchable material is a shape memory alloy, and the stimulus applying means includes:
A configuration may be adopted in which the spacer member is heated to change the substrate interval.

Further, as described in the sixth aspect, in the image display medium according to the third aspect, the stimulus-responsive elastic material is an elastic body, and the stimulus imparting means is provided in a surrounding environment of the spacer member. The pressure state may be controlled to change the substrate interval.

Further, in the image display medium according to the first or second aspect, as described in the seventh aspect, the support means is made of an elastic body which supports the substrates at predetermined intervals. A spacer member, and an elliptical columnar cam body arranged so that a rotation axis is parallel to the surface of the substrate; and a driving unit that rotates the cam body to change the substrate interval.
Can be provided.

In the present invention, the space between the substrates is mechanically expanded by the action of the cam body. In the present invention, when the short axis in the cross section of the cam body is arranged perpendicular to the substrate surface, the distance between the substrates is reduced, and when the long axis of the cross-sectional dimension of the cam body is arranged perpendicular to the substrate surface, The distance between the substrates increases.

The spacer member is made of, for example, an elastic body such as rubber or a polymer material, and supports the distance between the substrates variably. For example, the short axis in the cross section of the cam body and the height of the spacer member are made equal, and the long axis of the cross section dimension of the cam body is arranged perpendicular to the substrate surface so that the spacer member expands when the distance between the substrates becomes longer. Or the height of the spacer member is made equal to the long axis in the cross section of the cam body, and the short axis of the cross-sectional dimension of the cam body is arranged perpendicular to the substrate surface so that the spacer member shrinks when the distance between the substrates is reduced. The height of the spacer member is made equal to the intermediate length between the short axis in the cross section of the cam body and the long axis in the cross section of the cam body, and the long axis of the cross section of the cam body is arranged perpendicular to the substrate surface. The spacer member can be configured such that the longer the distance, the longer the spacer member, and the short axis of the cross-sectional dimension of the cam body is arranged perpendicular to the substrate surface, and the shorter the distance between the substrates, the shorter the spacer member.

The driving means changes the longitudinal direction of the cross section of the cam body with respect to the substrate surface by rotating the cam body, and adjusts the distance between the substrates.

Preferably, when an electric field is generated between the substrates for writing an image, the driving means rotates the cam so that the major axis of the cross-sectional dimension of the cam is arranged perpendicular to the substrate surface. When the image is displayed after forming the image, the driving means controls the rotation of the cam so that the short axis of the cross-sectional dimension of the cam is perpendicular to the substrate surface. To be configured.

Preferably, the length of the major axis of the cross-sectional dimension of the cam body is equal to the distance between the substrates at which particles can move smoothly, and the length of the minor axis of the cross-sectional dimension of the cam body is
It is preferable that the distance between the substrates is equal to the distance at which the particles hardly move.

With such a configuration, when the particles frequently move, the particles can move quickly to form a good image. When the particles do not move frequently, the movement of the particles is hindered, and the particles can be prevented from peeling. In particular, when the image display medium is placed vertically, the bias of particles due to gravity is prevented, and a stable image can be held for a long period of time.

Further, in the image display medium according to the first or second aspect, as described in the eighth aspect, the supporting means is a spacer made of an elastic body which variably supports the distance between the substrates. A member may be provided, and a slide unit that slides one of the pair of substrates facing each other among the plurality of substrates in a direction intersecting the surface of the substrate without changing the direction of the substrate surface.

In the present invention, the space between the substrates is mechanically spread by the action of the slide means. In the present invention,
The sliding means slides one of the pair of opposed substrates among the plurality of substrates in a direction intersecting the surface of the substrate without changing the direction of the substrate surface. As a result, the distance between the substrates increases or decreases, so that the spacer member expands and contracts accordingly. The distance between the substrates varies depending on the sliding direction of the substrate with respect to the direction intersecting the surface of the substrate.

Further, according to the present invention, as set forth in claim 9, the image display medium according to any one of claims 1 to 8 is used, and the pair of electrodes is provided in accordance with image information. Image display device having a display control means for applying a voltage between the substrates to generate an electric field between the substrates according to the image information.

According to the present invention, there is provided a display control means for generating an electric field for a pair of electrodes of the image display medium in accordance with image information. Thereby, the particles sealed between the substrates can be moved according to the image information, and an image can be formed by the color of the particles attached to the display substrate side.

The provision of the display control means makes it possible to easily rewrite an image. The display control means may be formed integrally with the image display medium or may be formed separately. In the case of integrally forming, the image can be easily rewritten. Further, in the case where the image display medium is formed separately, the image display medium on which the image is displayed by the display control means can be installed at a desired place away from the display control means. Therefore, the space required for installation can be reduced. Another advantage is that one display control means can be used for a plurality of image display media.

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an example of an embodiment to which an image display medium and an image display device of the present invention are applied will be described in detail with reference to the drawings.

(First Embodiment) As shown in FIGS. 1A and 1B, an image display device according to a first embodiment includes an image display unit 10 and a voltage control unit 12. It is configured. The image display unit 10 has a configuration in which a display-side electrode 22, a spacer 26a, and a back-side electrode 25 are sequentially formed between a transparent display substrate 20 forming an image display surface and a rear substrate 23. Although not shown, the display-side electrode 22
A transparent surface coat layer is formed on the surface of the backside electrode 25 and the backside electrode 25, respectively.

Note that the image display device corresponds to the image display device of the present invention, the image display unit 10 corresponds to the image display medium of the present invention, and the display substrate 20 and the back substrate 23 constituting the image display unit 10 are the same. The display-side electrode 2 corresponds to a plurality of substrates of the invention.
2 and the back electrode 25 correspond to a pair of electrodes of the present invention, and the voltage control unit 12 corresponds to a display control unit of the present invention.

In the first embodiment, as the display substrate 20, for example, length × width × thickness = 50 mm × 50 mm ×
It is composed of a transparent 7059 glass substrate with ITO of about 1.1 mm. Further, the rear substrate 23 is formed of, for example, an epoxy substrate of about 50 mm × 50 mm × 3 mm in length × width × thickness. Also, the display substrate 2
The distance between 0 and the rear substrate 23 is, for example, about 200 μm. Of course, the present invention is not limited to these values.

Between the display substrate 20 and the rear substrate 23,
As shown in FIGS. 2A and 2B, a spacer 26a formed in a lattice shape is provided. This spacer 2
6a is composed of a stimuli-responsive polymer gel that expands and contracts by an electric field. The spacer 26a and the display substrate 2
The gap control electrode 21 is embedded in each of the connection surface between the spacer 26a and the spacer 26a and the back substrate 23.

The voltage control section 12 described later is connected to the interval control electrode 21. The spacer 26a is stimulated by the electric field generated by the voltage applied to the distance control electrode 21 by the voltage control unit 12, and FIG.
The display substrate 20 and the rear substrate 2 are stretched as shown in FIG.
3 is widened. In the present embodiment, the spacer 26a normally has, for example, 70
It has a height of about μm.
A material having a configuration of about m is used. Of course, the present invention is not limited to these numerical values. This spacer 26a
Corresponds to the spacer member of the present invention, and the distance control electrode 21
The voltage controller 12 corresponds to the stimulus applying unit of the present invention.

The spacers 26 a define the unit cells 11, and each unit cell 11 contains colored particles (black particles) 4.
0 and white particles 42 are enclosed. Unit cell 11
Here, as the white particles 42 encapsulated, a titanium oxide-containing cross-linked polymethyl having a volume average particle diameter of 20 μm obtained by mixing fine powder of titania treated with isopropyltrimethoxysilane at a weight ratio of 100 to 0.1 is used. Spherical white particles of methacrylate (Techpolymer MBX-20-White manufactured by Sekisui Chemical Co., Ltd.) were used. As the black particles 40, aerosol A130 fine powder treated with aminopropyltrimethoxysilane was used in a weight ratio of 100 to 0.1%. Spherical black particles of carbon-containing crosslinked polymethyl methacrylate having a volume average particle diameter of 20 μm (Techpolymer MBX-20-Black manufactured by Sekisui Plastics Co., Ltd.) mixed at a ratio of 2 are used.

In the first embodiment, mixed particles obtained by mixing the above-mentioned white particles 42 and black particles 40 at a weight ratio of 2: 1 are contained in the unit cell 11 in the volume of the unit cell 11. About 10% of the amount is sealed. In the present embodiment, the white particles 42 are negatively charged, and the black particles 40 are positively charged.

Here, the image display unit 10 is a unit cell 1
After the mixed particles of about 10% with respect to the volume of 1 are uniformly shaken down into the unit cell 11 through the screen,
The display substrate 20 on which the surface coat layer 24 and the display-side electrode 22 are formed is arranged with the surface coat layer 24 side facing the unit cell 11 and both substrates are pressed and held with a double clip, and the silicon rubber sheet and both sides are placed. It is formed by bringing the substrate into close contact.

A display-side electrode 22 as one of the pair of electrodes of the present invention is provided on the surface of the unit cell 11 on the display substrate 20 side, and a pair of electrodes of the present invention is provided on the surface of the rear substrate 23. The back side electrode 25 is provided as the other side. The display side electrode 22 and the back side electrode 25 are I
The display-side electrode 22 is connected to the voltage controller 12, and the back-side electrode 25 is grounded.

The voltage control section 12 is connected to the interval control electrode 21 and the display-side electrode 22 embedded in the spacer 26a. As described above, the voltage control unit 12 applies a voltage to the interval control electrode 21 to increase the distance between the display substrate 20 and the back substrate 23 and to increase the display-side electrode 22 provided for each unit cell. Are applied in accordance with image information. As a result, an electric field is generated for each unit cell, and the particles in the unit cell 11 move according to the generated electric field to display an image.

For example, when a positive DC voltage of, for example, about +350 V is applied to the display-side electrode 22 by the voltage controller 12, the electric field generated in the unit cell 11 causes the negative charge on the rear substrate 23 side. The white particles 42 move toward the display substrate 20, and the positively charged black particles 40 are electrostatically attracted to the rear substrate 23.

For this reason, only the white particles 42 are uniformly adhered to the display substrate 20 and a good white display (for example, reflection density ≦
0.3) is achieved. At this time, even if the minute amount of the black particles 40 charged to the opposite polarity is present on the display substrate 20 side, the amount of the black particles 40 is small compared to the amount of the white particles 42, so that the display image is hardly affected.

Next, when a negative DC voltage of, for example, about −350 V is applied to the display-side electrode 22 by the voltage control unit 12, the action of the electric field generated in the unit cell 11 causes
The positively charged black particles 40 on the rear substrate 23 side are
The white particles 42 that move to the 0 side and are negatively charged are electrostatically attracted to the rear substrate 23 side.

For this reason, only the black particles 40 are uniformly adhered to the display substrate 20, and a good black display (for example, reflection density ≧
1.6) is achieved. At this time, even if the minute amount of the white particles 42 having the opposite polarity is present on the display substrate 20 side, the amount of the white particles 42 is small compared to the amount of the black particles 40, so that the display image is hardly affected.

Here, the operation of the voltage control section 12 will be described with reference to the flowchart of FIG. First,
In step 100, it is determined whether there is an image writing instruction.

If it is determined in step 100 that an image writing instruction has been issued, the flow advances to step 102 to apply a voltage to the interval control electrode 21. As a result, the spacer 26a is extended, and the distance between the substrates between the display substrate 20 and the rear substrate 23 is increased (see FIG. 1B). The volume of the unit cell 11 increases, and the particles move easily.

In the next step 104, each unit cell is initialized, and particles adhering to the display substrate 20 are separated from the display substrate 20. Thereafter, in step 106, a voltage having a polarity corresponding to each unit cell to be written according to the image data is applied.

For example, in the unit cell 11 to which the positive DC voltage is applied, the white particles 42 move to the display substrate 20 side to display white, and in the unit cell 11 to which the negative DC voltage is applied,
The black particles 40 move to the display substrate 20 side to display black.
In the present embodiment, an image is displayed based on the contrast between white and black for each unit cell 11.

In the next step 108, it is determined whether a predetermined time has elapsed. That is, the time from the application of the voltage of the polarity corresponding to each unit cell according to the image data to the movement of the particles is determined in advance as a predetermined time,
After the elapse of the predetermined time, the movement of the particles is completed, and it can be determined that an image has been formed.

Accordingly, if it is determined in step 108 that the predetermined time has elapsed, the flow shifts to step 110 to cancel the application of the voltage to the interval control electrode 21 to reduce the distance between the substrates (FIG. 1A )reference). This reduces the volume of the unit cell 11 and makes it difficult for the particles to move, so that the particles do not easily peel off.

In the next step 112, the voltage applied to each unit cell is released. As a result, the supply of power is stopped, but the particles adhered to the display substrate 20 continue to adhere to the display substrate 20 due to its own charging characteristics, and the image display state is maintained.

In the first embodiment, the case where all the spacers 26a are made of the stimulus-responsive polymer gel which expands and contracts by the electric field has been described. For example, as shown in FIG. 4, a first spacer 26a formed of a stimulus-responsive polymer gel is not limited to the case where the first spacer 26a is formed of a polymer gel,
It can expand and contract according to the expansion and contraction state of the first spacer 26a,
For example, it is also possible to adopt a configuration in which the second spacer 26b made of an elastic body such as rubber or silicon is combined.

In this case, when a voltage is applied to the interval control electrode 21 by the voltage control section 12, the first spacer 26a expands as shown in FIG. And the second spacer 26b is extended by this pushing force, whereby the distance between the substrates is increased.

Further, the voltage control section 12 controls the distance control electrode 2
When the application of the voltage to 1 is released, the first spacer 26a returns to the original size as shown in FIG.
The second spacer 26b also returns to its original size due to the restoring force,
The distance between the substrates is reduced. Note that the other configuration is the same as the above-described configuration, and the description is omitted.

As described above, in the image display device of the first embodiment, the distance between the substrates is widened at the time of image formation, so that particles can easily move. Since the distance between the particles is narrowed and the particles are hard to move, image formation can be performed quickly, and after the image formation, the particles are not easily peeled off even when the voltage is released, so that power is consumed. Therefore, the display state of the image can be maintained for a long time. Further, even when image formation is repeatedly performed, it is possible to display images stably over time without deteriorating the image.

(Second Embodiment) An image display device according to a second embodiment is an application of the first embodiment,
Only different points from the first embodiment will be described.

First, in the second embodiment, the image display unit 1
The spacer 26c for controlling the distance between the 0 display substrate 20 and the rear substrate 23 is made of a shape memory alloy. In addition, as shown in FIGS. 6A and 6B, the back substrate 23 is provided with a heating element 28 for heating the spacer 26c. The heating element 28 is formed of a resistor, and is connected to the voltage control unit 12. The spacer 26c corresponds to the spacer member of the present invention, and the heating element 28
The voltage controller 12 corresponds to the stimulus applying unit of the present invention.

In the second embodiment, the voltage control section 12 applies a voltage to the heating element 28 provided on the rear substrate 23, whereby the heating element 28 generates heat. It is transmitted to the spacer 26c via the substrate 23,
The heat causes the spacer 26c to be heated and expanded, and the expansion force causes the display substrate 20c to expand as shown in FIG.
And the rear substrate 23 are pushed apart to increase the distance between the substrates.

When the application of the voltage to the heating element 28 by the voltage control unit 12 is released, the heating element 28 is naturally cooled, and the spacer 26c returns to the original size.
The distance between the substrates is reduced (see FIG. 6A). Note that, for example, a device such as a blower that actively cools the heating element 28 may be provided, and when the application of the voltage to the heating element 28 is released, the heating element 28 may be actively cooled. The other configuration is the same as the configuration of the first embodiment described above, and the description is omitted.

As described above, in the image display device of the second embodiment, during image formation, the distance between the substrates is widened so that particles can easily move. Since the distance between the particles is narrowed and the particles are hard to move, image formation can be performed quickly, and after the image formation, the particles are not easily peeled off even when the voltage is released, so that power is consumed. Therefore, the display state of the image can be maintained for a long time.

Also, by forming the spacer 26c of a shape memory alloy and heating it by the heating element 28, there is an advantage that the distance between the substrates can be varied with a relatively simple structure.

The heating element 28 is made of a material (electrothermal conversion element) that generates heat by applying a voltage, but the present invention is not limited to this, and a material that generates heat by light irradiation (photothermal conversion element), etc. Can also be applied.

(Third Embodiment) As shown in FIGS. 7 and 8, an image display unit 10 of an image display device according to a third embodiment comprises a transparent display substrate 20 forming an image display surface, The display-side electrode 22 and the spacer 26
d, the cam 27, and the back electrode 25 are formed in this order. Although not shown, transparent surface coat layers are formed on the surfaces of the display-side electrode 22 and the back-side electrode 25, respectively. The image display device according to the third embodiment includes a drive control unit 13. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description is omitted.

The image display unit 10 corresponds to the image display medium of the present invention, the drive control unit 13 corresponds to the drive unit of the present invention, and the display substrate 20 and the rear substrate 23 constituting the image display unit 10 The display-side electrode 22 corresponds to a plurality of substrates of the invention.
And the rear electrode 25 correspond to a pair of electrodes of the present invention, and the spacer 26d corresponds to a spacer member of the present invention.
Corresponds to the cam body of the present invention.

As shown in FIG. 7, between the display substrate 20 and the rear substrate 23, a spacer 26d and a cam 27 formed in a lattice are provided.

The spacer 26d is made of, for example, a stretchable elastic material such as rubber or silicon.
It is configured such that it can be extended when the distance between the substrate and the rear substrate 23 is increased.

The cam 27 is formed in an elliptic column shape, and the length of the short axis d1 (see FIG. 8A) of the cross section is the thickness of the unit cell when the particles hardly move, that is, when the image is displayed. Is determined so as to be equal to the distance between the substrates (for example, about 70 μm), and the length of the major axis d2 (see FIG. 8 (B)) of the cross section is the thickness of the unit cell when the particles easily move. That is, the distance between the substrates during image formation (for example, 20
(About 0 μm).

A motor M is provided on the cam shaft 27a via a gear 29 (see FIG. 7). The rotational force of the motor M is transmitted to the cam shaft 27a via the gear 29, and the cam shaft 27a The cam 27 rotates with the rotation. The distance between the display substrate 20 and the rear substrate 23 is determined by the diameter of the cross section of the cam 27.

At the time of writing an image, as shown in FIG. 8B, the cam 27 is rotated such that the long axis d2 of the cam 27 is perpendicular to the substrate surface, whereby the spacer 26d for supporting between the substrates is formed. To stretch. Thereby, the unit cell 1
1 becomes large, and particles easily move. After the image formation, as shown in FIG.
7 so that the short axis d1 of the cam 7 is perpendicular to the substrate surface.
7 is rotated so that the spacers 2 supporting between the substrates
6d returns from the expanded state to a state in which the distance between the substrates is reduced. As a result, the volume of the unit cell 11 is reduced, and the particles are hardly peeled off.

In this embodiment, the cam 27 is provided so as to also serve as the spacer 26d. Therefore, the portion where the cam 27 intersects with the spacer 26d is configured so that only the cam shaft 27a penetrates. Of course, the cam 27 can be configured to be provided independently of the spacer 26d defining the unit cell 11 so as to function only to spread the distance between the substrates.

In the third embodiment, the cam 27
Has been described, but a plurality of cams 27 are provided.
May be provided in parallel with each other, or may be provided so as to intersect with each other so as to generate a force for expanding the space between the substrates at some points. In addition, although the case where the cam 27 is provided on the edge of the image display unit 10 has been described, the present invention is not limited to this configuration, and the cam 27 can be provided at a desired position, such as the center, as appropriate.

Further, in the third embodiment, the motor M
Has described the case where the cam 27 is rotated by
Not only the motor M but also various other ones can be used as long as they have a driving force for rotating the cam 27.

For example, as shown in FIG. 9, an electromagnet 30 has a driving force for rotating the cam 27. In this case, one end of the cam 27 is N
The display substrate 20 is configured as a magnet whose pole and the other end are S poles.
The electromagnet 30 is provided along the longitudinal direction of the cam 27 on the outside of the rear substrate 23 and on the outside of the rear substrate 23, respectively.

The electromagnet 30 is connected to, for example, the voltage control unit 12, and when a voltage is applied by the voltage control unit 12, a magnetic field is generated. This magnetic field and the magnetic field of the cam 27 repel, and the cam 27 rotates to a position where the major axis direction is perpendicular to the substrate surface, thereby increasing the distance between the substrates. Also,
By changing the direction of the current applied to the electromagnet 30,
Since the positive and negative are reversed, the direction in which the cam 27 is oriented can also be changed. For example, when the voltage applied to the electromagnet 30 is changed so that the direction of the generated magnetic field is reversed, and the application of the voltage is stopped when the short-axis direction of the cam 27 is rotated to a position perpendicular to the substrate surface, the spacer The rotation of the cam 27 is suppressed by the restoring force of 26d, and the distance between the substrates is reduced. By such control, the direction of the cam 27 with respect to the substrate surface can be changed, and the distance between the substrates can be controlled.

(Fourth Embodiment) The fourth embodiment is an application of the third embodiment. Instead of using a cam, the inside is hollow as shown in FIGS. In this configuration, the distance between the substrates is controlled by expanding or contracting the hollow elastic body 34 by using the closed cylindrical elastic body 34.

The image display device of the fourth embodiment has a structure in which the substrates between the display substrate 20 and the rear substrate 23 of the image display unit 10 are sealed, and as shown in FIG. The pressure control device 36 is connected between the substrates.

As shown in FIGS. 10 and 11, the image display section 10 has a grid-like spacer 26d made of an elastic body between a display substrate 20 and a back substrate 23, and a columnar shape having a hollow inside. A hollow elastic body 34 is provided. The edge between the display substrate 20 and the rear substrate 23 is sealed with a sealing material to prevent the gas inside from leaking.

At the time of writing an image, the pressure between the substrates is reduced by the pressure control device 36 and the gas sealed inside the hollow elastic body 34 is expanded, so that the space between the display substrate 20 and the rear substrate 23 is expanded. Increase the distance (Fig. 1
1 (B)). Thereby, the volume of the unit cell 11 increases, and the particles easily move. After image formation, the pressure between the substrates is returned to the original pressure state by the pressure control device 36, or the pressure inside the hollow elastic body 34 is reduced to a pressure lower than the original pressure state, thereby returning the gas sealed inside the hollow elastic body 34 to the original volume. It is returned or compressed from its original volume to reduce the distance between the substrates (see FIG. 11A). As a result, the volume of the unit cell 11 is reduced, and the particles are hardly peeled off.

As described above, in the fourth embodiment, the distance between the substrates is changed by expanding or contracting the hollow elastic body 34 by changing the pressure state between the substrates. It should be noted that a liquid can be sealed between the substrates and the internal pressure can be controlled by taking the liquid in and out.

As an application example of the fourth embodiment,
By not filling the space between the substrates, filling the inside of the hollow elastic body with a substance having a low vapor pressure, and expanding or expanding or contracting the substance inside the hollow elastic body 34 by an external stimulus, thereby expanding or expanding the hollow elastic body 34. It is also possible to adopt a configuration for controlling the distance between the substrates. In this case, the external stimulus includes heat and light.

(Fifth Embodiment) As shown in FIGS. 12 and 13, an image display unit 10 of an image display device according to a fifth embodiment comprises a transparent display substrate 20 forming an image display surface. A display-side electrode 22 (FIG. 12)
, A spacer 26d (see FIG. 6), two sets of slide rails 31a and 31b, and a rear electrode 25 (FIG. 1).
2 are not shown). Also,
In the image display device according to the fifth embodiment, the display substrate 20
An eccentric cam 35 is provided along one side of the rectangular display substrate 20 in order to increase the distance between the substrate and the rear substrate 23. Although not shown, transparent surface coat layers are formed on the surfaces of the display-side electrode 22 and the back-side electrode 25, respectively. Further, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In the fifth embodiment, the image display section 10 corresponds to the image display medium of the present invention, and the display substrate 20 and the rear substrate 23 constituting the image display section 10 are formed by a plurality of substrates of the present invention. Correspondingly, the display side electrode 22 and the back side electrode 25
Corresponds to the pair of electrodes of the present invention, and the spacer 26d corresponds to the spacer member of the present invention.

Each of the slide rails 31a and 31b has a pair of rail members 3 having inclined surfaces 32 which engage with each other.
3a and 33b. Rail member 33a,
33b are provided on the surface of the display substrate 20 on the unit cell 11 side and the surface of the back substrate 23 on the unit cell 11 side, respectively, as shown in FIG.
The arrangement is determined so that the inclined surfaces 32 engage with each other when they are opposed to each other.

An eccentric cam 35 is provided at one edge of the display substrate 20, and the display substrate 20 is configured to be able to reciprocate linearly by using the eccentric cam 35 as a motor. Note that the slide rails 31a and 31b and the eccentric cam 35 correspond to the slide means of the present invention.

As shown in FIG. 13A, the eccentric cam 35
The state in which the rotating shaft 35a is disposed closest to the display substrate 20 is set as a reference state, and in this reference state, the inclined surfaces 32 of the rail members 33a and 33b are configured to match. In this reference state, the distance between the substrates is the shortest, and this reference state is set before or after image formation.

As shown in FIG. 13B, the eccentric cam 35
The state in which the rotation shaft 35a is located farthest from the display substrate 20 is referred to as an image forming state, and the display substrate 20 is pressed in the direction of arrow Y in FIG. It is. Accordingly, as the display substrate 20 moves in the direction of arrow Y, the inclined surface 32 of the rail member 33a on the display substrate 20 slides in a direction parallel to the inclined surface 32 of the rail member 33b on the back substrate 23 side. Then, the display substrate 20 is pushed obliquely upward along the inclined surface 32 without changing the direction of the substrate surface, and as a result, the distance between the substrates is widened. Thereby, a sufficient interval for the movement of the particles can be ensured during image formation, and thus, by forming an image in this state, good image formation can be performed.

As described above, in the fifth embodiment, the display substrate 20 is linearly moved by rotating the eccentric cam 35 provided along one side of the display substrate 20, thereby connecting the display substrate 20 to the rail member 33a. The distance between the substrates is changed by moving along the inclined surface 32. The rail members 33a, 33 constituting the slide rails 31a, 31b
The shape of b is not limited to this configuration.

(Sixth Embodiment) As shown in FIG. 14, an image display section 10 of an image display device according to a sixth embodiment has a transparent A display-side electrode 22 between the display substrate 20 and the rear substrate 23;
This is a configuration in which a spacer 26d (see FIG. 6) and a rear electrode 25 are sequentially formed. Note that, in the present embodiment, the display substrate 20 forms one surface of the housing 38. In the image display device according to the fifth embodiment, in order to increase the distance between the display substrate 20 and the rear substrate 23, the image display unit 1
A spring member 37 and a cam 27 having a substantially elliptical cross section are formed in a space formed by the rear side of the rear substrate 23 and one surface of the housing 38.
Is provided.

In the sixth embodiment, the spring member 37
Are provided at four corners of the rear substrate 23 and apply a biasing force to the rear substrate 23 in a direction away from the display substrate 20.
The cam 27 is formed in a substantially elliptical column shape, and when the major axis of the cross section is perpendicular to the substrate surface of the rear substrate 23, the distance between the display substrate 20 and the rear substrate 23 is reduced. It is configured so that the distance between the substrates becomes narrower (for example, about 70 μm), and the distance between the substrates becomes equal to the thickness of the unit cell when the particles hardly move. When this happens, the inter-substrate distance between the display substrate 20 and the back substrate 23 increases (for example, 200 μm).
And the distance between the substrates is equal to the thickness of the unit cell when the particles are likely to move.

The shaft of the cam 27 is connected to the motor M via a gear 29 (not shown) as in the third embodiment.
(Not shown), and a motor M (not shown)
Is transmitted to the cam 27 via the gear 29 (not shown), the cam 27 rotates to move the position of the rear substrate, and the distance between the substrates is determined. Note that the motor corresponds to the driving unit of the present invention.

At the time of image writing, as shown in FIG. 14B, the cam 27 is rotated so that the short axis of the cam 27 is perpendicular to the substrate surface, whereby the spacer 26d supporting the space between the substrates is extended. I do. Thereby, the unit cell 11
The volume of the particles increases, and the particles move easily. Also,
After the image formation, as shown in FIG.
The cam 27 is rotated so that the long axis of the substrate is perpendicular to the substrate surface, whereby the rear substrate 23 is pushed up, and the spacer 26d supporting the substrates returns from the expanded state to the original state, and the distance between the substrates is reduced. State. As a result, the volume of the unit cell 11 is reduced, and the particles are hardly peeled off.

In the sixth embodiment, the cam 27
Has been described, but a configuration in which one cam 27 is provided, or three or more cams 27 are provided in parallel with each other, or provided so as to intersect with each other to change the inter-substrate distance at several points. It is also possible to use

Further, in the third embodiment, the motor M
Has described the case where the cam 27 is rotated by
As long as it has a driving force for rotating the cam 27, not only the motor M but also various driving means such as the electromagnet 30 described in the third embodiment can be applied.

As an application of the sixth embodiment, the distance between the substrates of the image display unit 10 may be changed by controlling the pressure state around the image display unit 10 instead of using the cam 27. it can.

For example, the housing 3 for storing the image display unit 10
8 is a highly airtight sealed housing, preferably a space formed by the rear substrate 23 and one surface of the housing 38 is a highly airtight sealed housing, and this sealed housing is a fourth embodiment. The pressure control device 36 described above is connected, and the pressure state in the closed casing is controlled by the pressure control device 36.

In this case, the pressure state of the space formed by the back substrate 23 and one surface of the housing 38 is controlled to
By applying a force in a direction to approach the display substrate 20 or a force in a direction away from the display substrate 20, the spacer 26d is expanded and contracted, and the distance between the display substrate 20 and the rear substrate 23 is controlled.

As described above, in the image display devices according to the first to sixth embodiments, the distance between the display substrate 20 and the rear substrate 23 constituting the image display section 10 can be changed. The display substrate 20 during image formation
The distance between the display substrate 20 and the back substrate 23 can be increased to facilitate the movement of the particles, and after image formation, the distance between the display substrate 20 and the back substrate 23 can be reduced to make the particles hard to move. Therefore, at the time of displaying an image, no matter what angle the image display unit 10 is arranged, the individual particles constituting the formed image are hardly dropped from the display substrate.
It is possible to prevent the particles from being unevenly distributed between the substrates due to the missing particles, and to suppress the deterioration of the image quality such as a defective pixel due to the missing particles. Therefore, even when the image is displayed vertically, the image can be stably displayed over a long period of time.

[0109]

As described above, according to the present invention, there is an effect that an image can be stably displayed over a long period of time.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view illustrating a schematic configuration of an image display device according to a first embodiment of the present invention when displaying an image, and FIG. 1B is a cross-sectional view illustrating a first embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating a schematic configuration during image formation of the image display device according to the embodiment.

FIG. 2A is a perspective view illustrating a configuration of a spacer according to the first embodiment, and FIG. 2B is a top view illustrating a configuration of the spacer according to the first embodiment. FIG.

FIG. 3 is a flowchart illustrating an operation of a voltage control unit according to the first embodiment.

FIG. 4 is an explanatory perspective view showing a configuration of a spacer in the image display device to which the first embodiment is applied;

FIG. 5A is a cross-sectional view illustrating a schematic configuration of an image display device to which the first embodiment is applied when displaying an image, and FIG. 5B is a first embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating a schematic configuration of an image display device according to an embodiment at the time of image formation.

FIG. 6A is a cross-sectional view illustrating a schematic configuration of an image display device according to a second embodiment of the present invention when displaying an image, and FIG. 6B is a cross-sectional view illustrating the second embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating a schematic configuration during image formation of the image display device according to the embodiment.

FIG. 7 illustrates an image display device according to a third embodiment.
FIG. 3 is an explanatory perspective view illustrating a configuration between substrates of an image display unit.

FIG. 8A is a cross-sectional view illustrating a schematic configuration of an image display device according to a third embodiment of the present invention at the time of displaying an image, and FIG. FIG. 2 is a cross-sectional view illustrating a schematic configuration during image formation of the image display device according to the embodiment.

FIG. 9 is an explanatory perspective view showing another configuration example for driving a cam in the third embodiment.

FIG. 10 is a perspective explanatory view illustrating a configuration between substrates of an image display unit in an image display device according to a fourth embodiment.

FIG. 11A is a cross-sectional view illustrating a schematic configuration of an image display device according to a fourth embodiment of the present invention when displaying an image, and FIG. 11B is a cross-sectional view of the fourth embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating a schematic configuration during image formation of the image display device according to the embodiment.

FIG. 12 is an explanatory perspective view showing a configuration of an image display unit in the image display device according to the fifth embodiment.

FIG. 13A is a cross-sectional view illustrating a schematic configuration of an image display device according to a fifth embodiment of the present invention when displaying an image, and FIG. 13B is a cross-sectional view illustrating a fifth embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating a schematic configuration during image formation of the image display device according to the embodiment.

FIG. 14A is a cross-sectional view illustrating a schematic configuration of an image display device according to a sixth embodiment of the present invention when displaying an image, and FIG. 14B is a cross-sectional view illustrating a sixth embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating a schematic configuration during image formation of the image display device according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Image display part 11 Unit cell 12 Voltage control part 13 Drive control part 20 Display board 21 Interval control electrode 22 Display side electrode 23 Back substrate 24 Surface coat layer 25 Back side electrode 26a-26d Spacer 27 Cam 27a Cam shaft 28 Heat generation Body 29 Gear 30 Electromagnet 31a, 31b Slide rail 32 Inclined surface 33a, 33b Rail member 34 Hollow elastic body 35 Eccentric cam 35a Rotation axis 36 Pressure controller 37 Spring member 38 Housing 40 Black particle 42 White particle

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Nobuyuki Nakayama 430 Green Tech Nakai, Nakai-cho, Ashigara-gun, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. Inside (72) Inventor Motohiko Sakemaki 430 Green Tech Nakai, Nakai-cho, Ashigara-kami, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor Horiuchi 430 Green Tech Nakai, Nakai-cho, Ashigara-gun, Kanagawa Fuji Green X (72) Inventor Ken Matsunaga 430 Green Tech Nakai, Nakai-cho, Ashigara-kami, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd.

Claims (9)

[Claims] A plurality of substrates that are transparent at least on a display side and are stacked and arranged; and a pair of electrodes that generate an electric field in a space formed between the substrates by applying a voltage corresponding to image information; At least two types of particle groups that are sealed between a plurality of substrates and have different colors and charging characteristics, and are provided between the plurality of stacked substrates, respectively, and variably support the distance between the substrates. Means, and an image display medium comprising: 2. The image display medium according to claim 1, wherein the support unit increases a distance between the substrates when an electric field is generated between the substrates. 3. The apparatus according to claim 2, wherein the supporting means includes a spacer member made of a stimulus-responsive stretchable material that expands and contracts due to a stimulus, and stimulus applying means that applies a stimulus to the spacer member. The image display medium according to claim 1 or 2. 4. The stimulus-responsive stretchable material is an electric-field-responsive material that expands and contracts when an electric field is applied, and the stimulus applying unit changes the distance between the substrates by controlling an applied state of an electric field applied to the spacer member. The image display medium according to claim 3, wherein 5. The image according to claim 3, wherein the stimulus-responsive elastic material is a shape memory alloy, and the stimulus applying unit changes the substrate interval by heating the spacer member. Display medium. 6. The stimulus-responsive stretchable material is an elastic body, and the stimulus applying unit controls the pressure state of the surrounding environment of the spacer member to change the distance between the substrates. 4. The image display medium according to 3. 7. The support means includes: a spacer member made of an elastic body that supports the distance between the substrates so as to be variable; and an elliptical columnar cam body arranged so that a rotation axis is parallel to a surface of the substrate. 3. A driving means for rotating the cam body to change the substrate interval.
2. The image display medium according to 1. 8. A supporting member, comprising: a spacer member made of an elastic body that variably supports a distance between the substrates; and a direction of one substrate surface of a pair of substrates facing each other among the plurality of substrates is changed. 3. The image display medium according to claim 1, further comprising: a slide unit configured to slide in a direction intersecting with a surface of the substrate. 9. An image display medium according to claim 1, wherein a voltage is applied to said pair of electrodes in accordance with image information, and image information is applied between said substrates. An image display device comprising display control means for generating a corresponding electric field.