JP2002156664A - Method for displaying image and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a high-quality image by using a reversible static image display medium which can repeatedly display images and by subjecting the medium to the initialization treatment such as erasing images before displaying an image and (or) by allowing the developing particles to easily move for displaying an image. SOLUTION: An image is displayed by using a reversible image display medium D1 which houses a developer DL containing white developing particles WP and black magnetic developing particles BP having triboelectrification property and different electrification polarities and different optical reflection densities from each other in cells 116 between two substrates 111, 112 and which can display an image by applying an electrostatic field according to the image to be formed so as to drive the developing particles. Prior to the image display process and (or) in the image display process, an oscillating magnetic field is applied on the developer DL in the image display medium D1 by using devices IN4 and (or) IN5 which impart magnetic stirring force to generate stirring force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image display method and an image forming apparatus. In particular, the present invention relates to an image display method and an image forming apparatus for displaying an image on a reversible image display medium capable of repeatedly performing image display and image deletion.

[0002]

2. Description of the Related Art Today's image displays include pencils, pens,
Manually write characters and graphics on an image display medium such as paper using paints, etc .; display documents and graphics created by a computer, word processor, etc. on a display such as a CRT display; This is done by, for example, displaying an output on a medium.

Further, a document, a figure, or the like, which is manually created on a medium such as paper, or a document, a figure, or the like on a medium such as paper output by a printer is printed on another medium such as paper using a copying machine or the like. In some cases, a copy is made, or transmitted by a facsimile machine or the like, and copied and output on a medium such as paper at a transmission destination.

[0004]

Among these image displays, characters, characters and the like are displayed on an image display medium such as paper using a pencil, a pen or the like.
Image display for displaying figures, etc., and image display for displaying characters, figures, etc. on an image display medium such as paper by an image forming apparatus such as an electrophotographic system, an ink spraying system, a thermal transfer system, etc., such as a printer, a copying machine, or a facsimile machine. Then, a clear image can be displayed at a high resolution, and the image is easy to see when viewing the image.

However, it is not possible to repeat image display and image deletion on an image display medium such as paper. When writing letters and the like using a pencil, the letters and the like can be erased to some extent with an eraser, but if the letters etc. are thinly written, they will be completely erased if they are written with normal darkness. It is difficult to leave, and it is difficult to reuse a medium, such as paper, on which an image has been displayed, unless the image is also displayed on the back side of the medium on which an image has not been displayed.

[0006] Therefore, a medium such as paper on which an image is displayed is discarded or incinerated after it has been used up, and a lot of resources are consumed. In printers and copiers, consumables such as toner and ink are also consumed. Further, in order to obtain a display medium such as new paper, toner, ink, and the like, resources such as a medium and energy for manufacturing the medium are further required. This is contrary to the demand for environmental load reduction required today.

In this regard, in the image display on a display such as a CRT display, image display and image deletion can be repeated. However, the image displayed on the display has a lower resolution than the image displayed on a paper or the like by a printer or the like, and there is a limit to obtaining a clear and fine image. Since the resolution is low, it is not suitable for displaying a text document mainly composed of characters. A sentence or the like that fits into about one screen is still good, but a sentence or the like that continues over a plurality of screens is difficult to read and sometimes difficult to understand. In addition, eyes are very apt to be tired in long-term visual work due to relatively low resolution and light emission from the display.

As an image display method capable of repeating image display and image deletion, electrophoretic display (EP
D) and twisted ball type display (TBD) have been proposed. More recently, the method introduced in "Japan Hardcopy '99 Transactions PP249-252" has been proposed.

In the electrophoretic display method, a sealed space is formed by arranging two substrates, at least one of which is transparent, at an interval with a spacer interposed therebetween to form a sealed space, in which particles having electrophoretic ability are formed. It is filled with a display liquid dispersed in a dispersion medium of a different color, and displays images in the color of the particles or the color of the dispersion medium by migrating particles in the display liquid in an electrostatic field. is there.

Such a display liquid is usually composed of a dispersion medium such as isoparaffin, fine particles such as titanium dioxide, a dye for imparting color contrast with the fine particles, a dispersant such as a surfactant, and additives such as a charge imparting agent. Is done.

However, in this electrophoretic display,
Since the contrast between the high refractive index particles (inorganic pigment) such as titanium dioxide and the insulating colored liquid is displayed, the degree of concealment of the colored liquid is inevitably low, and the contrast is reduced.

Furthermore, the types of dyes that can be dissolved in a high-concentration nonpolar solvent at a high concentration so as to enable electrophoresis of particles are limited. No black dye is known. Therefore, the background part is inevitably colored, and it is difficult to make the background part white and improve the contrast. When white particles for forming an image are put in the colored liquid, the colored liquid may enter between the substrate and the white particle layer moved to the image observation side substrate, or the colored liquid may be mixed between the white particles. And the contrast is reduced. Also, the resolution of the electrophoretic particles is low because it is difficult for the particles to be uniformly attached to the image observation side substrate.

Further, since the specific gravity difference between the particles and the dispersion medium in the display liquid is very large, and the particles are likely to settle and agglomerate,
The display contrast tends to decrease, and it is difficult to display images stably for a long period of time, and the previous display afterimage tends to occur. Further, the charging of the particles in the liquid greatly changes with time, and in this respect, the image display stability is also poor.

In the twisting ball type display method, a large number of microcapsules in which microspheres treated so that the half and the other half of the surface exhibit mutually different colors or optical densities together with an insulating liquid are held inside. Using an image display medium, a microsphere in the microcapsule is rotated by an electric field or a magnetic force to display an image in a predetermined color.

However, in this twisted ball type display, it is difficult to obtain a good contrast because an image is displayed by microspheres in an insulating liquid in a microcapsule, and in particular, a resolution is lowered because a gap is always formed between the microcapsules. . It is difficult to reduce the size of the microcapsule in order to improve the resolution in manufacturing the capsule.

"Japan Hardcopy '99 Transactions PP249
The image display method introduced in 252252 ”is a method in which two substrates each having an electrode and a charge transport layer laminated thereon are opposed to each other at a predetermined interval to form a sealed space, in which a conductive toner and a conductive toner and a conductive toner are formed. Insulating particles having different colors are enclosed, an electrostatic field is applied to charge and charge the conductive toner, and the conductive toner is moved by Coulomb force to display an image.

However, in the image display method utilizing the charge injection phenomenon, when the charge-injected conductive toner moves,
Insulating particles (for example, white particles that are put together to obtain the background color) hinder the movement of the conductive toner, and some toners stop moving. As a result, sufficient image density and contrast cannot be obtained, and the image display speed decreases. In order to solve this problem, high voltage driving is required. Also, the resolution is limited to the resolution determined by the electrodes. In addition, it is essential to employ an electrode, a charge injection layer, and a conductive toner, and there is a limitation in manufacturing.

Therefore, according to the present invention, image display and image erasure can be repeatedly performed, so that the use of consumables such as an image display medium such as paper and a developer and ink related to the conventional image formation can be reduced. It is an object of the present invention to provide an image display method and an image forming apparatus capable of responding to the reduction of the environmental load of today.

Another object of the present invention is to provide an image display method and an image forming apparatus capable of displaying a high-contrast image with high contrast.

Another object of the present invention is to provide an image display method and an image forming apparatus capable of displaying a high-resolution image with high resolution.

It is another object of the present invention to provide an image display method and an image forming apparatus which are less likely to cause an afterimage and can display a high quality image.

Still another object of the present invention is to provide an image display method and an image forming apparatus capable of displaying images at high speed.

Another object of the present invention is to provide an image display method and an image forming apparatus which require a low drive voltage.

[0024]

The present invention provides the following image display method and image forming apparatus. (1) Image display method Two substrates facing each other with a predetermined gap, and
One or two or more developer storage cells formed between two substrates and surrounded by a partition wall, and a dry developer included in each of the cells, wherein the dry developer includes: At least two types of triboelectrically-charged dry developing particles having different charging polarities and different optical reflection densities are included, and at least one of the at least two types of developing particles is magnetic. Preparing a reversible image display medium which is a developing particle, and applying an electrostatic field corresponding to an image to be formed on the frictionally charged developing particles having opposite polarities in the reversible image display medium to form the developing particles. An image display step of driving and displaying an image, wherein before and / or during the image display step, a magnetic field is externally applied to the developer in the reversible image display medium so that the developer is applied. Stirring power An image display method for magnetic stirring force imparted on. (2) Image forming apparatus: two substrates facing each other with a predetermined gap;
One or two or more developer storage cells formed between two substrates and surrounded by a partition wall, and a dry developer included in each of the cells, wherein the dry developer includes: At least two types of triboelectrically-charged dry developing particles having different charging polarities and different optical reflection densities are included, and at least one of the at least two types of developing particles is magnetic. Image formation using a reversible image display medium, which is a developing particle, to display an image by driving frictionally charged developing particles having opposite polarities in the reversible image display medium in an electrostatic field corresponding to an image to be formed. An apparatus for applying an external magnetic field to a developer in the reversible image display medium before displaying an image on the reversible image display medium and / or in displaying an image on the reversible image display medium. The present At least one and has an image forming apparatus equipped with a magnetic stir force application device exerting stirring force on agent.

According to the image display method and the image forming apparatus of the present invention, an image to be displayed on the developing particles contained in each cell of the reversible image display medium in a state where the particles are triboelectrically charged. By forming an electrostatic field correspondingly, the developing particles are moved by Coulomb force to perform development, and an image is displayed.

The electrostatic field corresponding to the image to be formed can be obtained by providing electrodes on each of the medium constituting substrates, applying a voltage corresponding to the image to be formed between the electrodes, or applying an image to be formed on one of the substrates. Can be formed by forming an electrostatic latent image corresponding to.

The reversible image display medium used in the method and apparatus of the present invention is formed by two substrates facing each other with a predetermined gap therebetween, and is formed between the two substrates and surrounded by a partition wall. Or two or more developer storage cells and a dry developer contained in each cell, wherein the dry developers have at least two types of charge polarities different from each other and optical reflection densities different from each other. Dry developing particles having a triboelectric charging property. Therefore, even after displaying an image once, the image can be erased by applying a different electrostatic field, an alternating electric field, an oscillating magnetic field, or the like, or the image can be rewritten by applying a different electrostatic field. Therefore, there is no need to discard the image display medium on which the image has been displayed. Also,
The developing particles are contained in the cell, and do not require an external supply of the developer. In the image display method and the image forming apparatus according to the present invention using such a reversible image display medium, it is possible to greatly reduce the use of conventional image display media such as paper related to image display and consumables such as a developer. it can.

Further, unlike the conventional electrophotographic image formation, it is not necessary to dissolve and fix the toner on a sheet such as paper with heat, and the image forming energy required for this type of conventional image formation is not required. Can save most.

Thus, it is possible to meet today's environmental load reduction.

According to the image display method and the image forming apparatus of the present invention, the developers contained in the cells have different optical reflection densities (in other words, "different contrast" or "color difference"). Different)) at least two types of developing particles, and the developing particles are dry type developing particles, and the degree of hiding of the other type of developing particles by one type of developing particles is good, so that good contrast is obtained. Can be displayed on the screen.

The developer contained in the cell contains at least two types of mutually triboelectrically chargeable dry developing particles having different charging polarities. When an image is displayed, the developer is charged to the opposite polarity by friction charging. Since the particles move under the Coulomb force, the particles are easy to move, and in this respect, the image can be displayed with good contrast, the afterimage of the previous display hardly occurs, the image can be displayed at a high speed, and further, low voltage driving is possible. .

The dry-developed particles are less likely to settle and agglomerate because no liquid is interposed therebetween, as compared with, for example, the electrophoretic particles in the display liquid used for the electrophoretic image display described above. A decrease in contrast is unlikely to occur, and a long-term stable image display can be performed. Since the sedimentation and aggregation of the developing particles hardly occur, the afterimage of the previous display hardly occurs. Further, since dry development particles have less change over time in charging performance than particles in a liquid, stable image display can be performed for a long time in this respect as well.

Further, compared with the conventional image display by a CRT display or the like, the image can be displayed with a high resolution and easily to the eyes.

In particular, according to the image display method of the present invention, a reversible image display medium in which at least one type of developing particles among at least two types of included developing particles is magnetic developing particles is used. Before the image display step and / or in the image display step, an external magnetic field is applied to the developer in the image display medium to exert a stirring force on the developer.

When a magnetic stirring force is applied to the developer before the image display step, the developer containing the magnetically developed particles is stirred prior to the image display. In addition, it is possible to suppress the uneven distribution of each developing particle in the medium and to make the distribution uniform, and to obtain a good charged state of the developing particles. As a result, a high quality image can be displayed in the subsequent image forming process.

When a magnetic stirring force is applied to the developer in the image display step, the movement of the developing particles to be moved is smoothed by the application of the electrostatic field, so that a high-quality image can be displayed at a high speed with a low voltage drive. be able to.

In the image forming apparatus according to the present invention, the developer in the reversible image display medium may be used before the image is displayed on the reversible image display medium and / or when the image is displayed on the reversible image display medium. At least one magnetic stirring force applying device for applying a magnetic field from outside to exert a stirring force on the developer is provided.

Therefore, when the magnetic stirring force applying device exerts a stirring force on the developer before displaying an image, the developer containing the magnetic developing particles can be stirred by the device prior to displaying the image, whereby In addition, when there is a previous image, the image can be erased to suppress the occurrence of an afterimage, the uneven distribution of the developing particles in the medium and the uniform distribution can be achieved, and a good charged state of the developing particles can be obtained. Thus, high-quality image display can be performed thereafter.

Further, when the magnetic stirring force applying device exerts a stirring force on the developer in displaying an image, the device applies a stirring force to the developing particles to be moved by applying an electrostatic field, thereby causing the developer to move. , And a high-quality image can be displayed at high speed with low voltage driving.

When both such a device for displaying images and such a device for displaying images are provided, a higher quality image can be formed.

Further, in the image display method and the image forming apparatus according to the present invention, since the developer is stirred by magnetic force, the developer can be stirred efficiently.

As a method of applying the magnetic stirring force in the image display method according to the present invention, a developer is prepared by placing a magnetic field generating member on a reversible image display medium and relatively moving the image display medium and the surface of the magnetic field generating member. A method of oscillating the magnetic field strength applied to the device, in other words, generating an oscillating magnetic field (oscillating magnetic field) to exert a stirring force can be exemplified.

In this case, the magnetic field generating member can face at least one side of the reversible image display medium.

In any case, the following case can be exemplified for at least one magnetic field generating member. (A) The relative movement direction between the surface of the magnetic field generating member and the reversible image display medium is a predetermined direction, and the magnetic field generating member is a magnetic field generating member having magnetic poles arranged in the predetermined one direction. (B) The relative movement direction between the surface of the magnetic field generating member and the reversible image display medium is a predetermined direction and a direction crossing the predetermined direction, and the magnetic field generating member has magnetic poles arranged in the transverse direction. Is used. (C) The relative movement direction between the surface of the magnetic field generating member and the reversible image display medium is a predetermined direction, and the magnetic poles are arranged as the magnetic field generating member at a predetermined angle with respect to the predetermined direction. A magnetic field generating member is used. (D) the relative movement direction between the surface of the magnetic field generating member and the reversible image display medium is a predetermined direction, and at least two rows of magnetic poles are arranged as the magnetic field generating member in a direction crossing the predetermined direction; In adjacent magnetic pole rows, N
A magnetic field generating member whose pole position and S pole position are shifted from each other is used.

In any case, the magnetic field generating members may face both surfaces of the reversible image display medium, and the magnetic field generating members facing both surfaces of the medium may be magnetic field generating members having different magnetic pole arrangements.

In any case, the shape of the magnetic field generating member may be any shape such as a rotatable roller shape and a plate shape.

The magnetic stirring device in the image forming apparatus according to the present invention includes a magnetic field generating member facing the reversible image display medium, and a relative movement between the reversible image display medium and the surface of the magnetic field generating member. A device that vibrates the magnetic field applied to the developer (in other words, generates an oscillating magnetic field (oscillating magnetic field)) can be exemplified.

In this case, the magnetic stirring device can be provided with a magnetic field generating member that faces at least one side of the reversible image display medium.

In any case, the following case can be exemplified for at least one magnetic field generating member in at least one magnetic stirring force applying device. (A) The relative movement direction between the surface of the magnetic field generating member and the reversible image display medium is one predetermined direction, and the magnetic field generating member has magnetic poles arranged in the predetermined one direction. (B) The relative movement direction between the surface of the magnetic field generating member and the reversible image display medium is a predetermined direction and a direction crossing the direction, and the magnetic field generating member has magnetic poles arranged in the crossing direction. I have. (C) The relative movement direction between the surface of the magnetic field generating member and the reversible image display medium is a predetermined direction, and the magnetic field generating member is arranged in a direction in which the magnetic poles are arranged at a predetermined angle with respect to the predetermined direction. have. (D) the relative movement direction between the surface of the magnetic field generating member and the reversible image display medium is a predetermined direction;
At least two magnetic pole rows are provided in a direction transverse to the predetermined direction, and adjacent magnetic pole rows have N poles in the magnetic pole row direction.
The pole position and the S pole position are shifted from each other.

In any case, at least one magnetic stirring device has a magnetic field generating member facing both sides of the reversible image display medium, and the magnetic field generating members facing both sides of the medium have different magnetic pole arrangements. You may.

In the image forming apparatus according to the present invention, the shape of the magnetic field generating member may be any of a rotatable roller shape and a plate shape.

[0052]

Embodiments of the present invention will be described below.

The reversible image display medium used in the image display method and the image forming apparatus according to the embodiment of the present invention basically has the following configuration.

That is, two substrates facing each other at a predetermined gap, one or more developer storage cells formed between the two substrates and surrounded by partition walls, and This is a reversible image display medium having a dry developer contained in each cell. The dry developer contains at least two types of dry developing particles having triboelectric charging properties, which have different charging polarities and different optical reflection densities.

According to this reversible image display medium, it is necessary to apply a predetermined electrostatic field corresponding to an image to be displayed on the developing particles while the developing particles contained in each cell are triboelectrically charged. Then, the developing can be performed by moving the developing particles by the Coulomb force acting between the electrostatic field and the charged developing particles, and an image can be displayed with a predetermined contrast.

The electrostatic field can be formed based on the electrostatic latent image by forming an electrostatic latent image on the outer surface of one of the two substrates, for example. The formation of the electrostatic field may be performed simultaneously with the formation of the electrostatic latent image, or may be performed after the formation of the electrostatic latent image. Such an electrostatic field may be applied to a substrate opposite to the substrate on which an electrostatic latent image is formed, for example, by applying a bias voltage simultaneously with or after the formation of the electrostatic latent image, or by applying a bias voltage to the opposite substrate. It is obtained by setting the opposite substrate to a predetermined potential for forming an electrostatic field by grounding or the like.

Various materials can be selected and employed for the partition walls forming the substrate and the cells. As the substrate, a glass substrate, a rigid or flexible synthetic resin substrate, or the like can be employed. A flexible film-like substrate can also be employed.

At least one of the two substrates constituting the medium (the one disposed on the image observing side) should have a light transmitting property so that the displayed image can be visually recognized.

When forming an electrostatic latent image on a substrate, the substrate may be an insulating substrate.

The substrate on the side opposite to the substrate on which the electrostatic latent image is formed (for example, the substrate on the non-image observation side) may or may not be an insulating substrate. When an insulating substrate is used, this may be set to the ground potential, or when it is necessary to apply a bias voltage thereto, the insulating substrate may be left as it is.For example, a conductive film may be formed on the outer surface of the substrate, or the entire substrate may be used. It may be formed of a conductive material or a material containing a conductive material. In this way, the substrate can be easily grounded to a ground potential or a bias voltage can be applied to the substrate if necessary. Further, when the opposite substrate is an insulating substrate and a conductive film is formed on the outer surface thereof, or when the opposite substrate itself is a conductive substrate, there is an effect of shielding charges from other components. In addition, even when the media on which images are displayed are overlapped, the images are less likely to collapse, and the images can be held more stably.

The number, size, shape, distribution, arrangement (regular or irregular) of the developer containing cells are not particularly limited as long as images can be displayed.

A developer movement suppressing member and a spacer for maintaining a gap between the substrates may be provided between the substrates. The partition wall constituting the cell may also serve as the developer movement suppressing member and the spacer.

FIG. 26 exemplifies some forms of the cell CEL in the reversible image display medium D. The medium D shown in FIG. 26A has a plurality of cells having a continuous groove shape arranged in parallel so as to extend in the lateral direction of the medium. FIG.
The medium D of (B) has a plurality of rectangular cells arranged in series in each of the longitudinal direction and the lateral direction of the medium. The medium D in FIG. 26C is arranged in series in the short direction of the medium while being shifted in the longitudinal direction, and has cells arranged in a brick wall shape as a whole. FIG.
The medium D of (D) is arranged in series in each of the longitudinal direction and the lateral direction of the medium, and has a plurality of square cells having a grid pattern as a whole. Medium D in FIG. 26 (E)
Is a single cell having a plurality of inter-substrate spacers in the cell.

In any case, the smaller the cell, the smaller the bias of the developer. However, the ratio occupied by the partition wall increases, and accordingly, the developer storage amount decreases, and the contrast of the image density decreases. The larger the cell, the better the contrast, but the greater the bias of the developer. Therefore, the size of one cell may be such that the bias of the developer is suppressed and a satisfactory contrast is obtained.

In the case where an electrostatic latent image is formed on a substrate during image formation, if the gap between the substrates or the thickness of the substrate is large, the electric field applied to the developer becomes weak, leading to a decrease in contrast. On the other hand, if the gap between the substrates is too small, the amount of developer that can be included is small, and the contrast is low. If the thickness of the substrate is too small, the substrate is easily bent, and uniformity of the gap between the substrates cannot be obtained,
Image unevenness is likely to occur. Therefore, the thickness of the substrate is 5
μm-100 μm, gap between substrates 20 μm-300
μm, and the thickness of the entire medium is suitably 30 μm to 500 μm.

With respect to the frictional charging of the developing particles, the developing particles may be stored in a developer storage cell and then frictionally charged by vibrating the developer particles. However, two or more types of developing particles may be mixed and stirred in advance. The developer particles triboelectrically charged may be accommodated in the cell. This makes it easier to obtain frictionally charged developing particles in a desired state. In any case, the developing particles are triboelectrically charged prior to image display.

In any case, the reversible image display medium is
It may have an electrode or may not have an electrode. When no electrode is provided on the substrate, the medium can be simplified accordingly, and a flexible film substrate or the like can be easily used as the substrate.

As an image display medium having electrodes, an electrode (preferably a transparent electrode) is formed on the inner surface of one substrate having light transmittance, and an electrode facing the electrode is formed on the inner surface of the other substrate. Can be exemplified.

The electrodes on the inner surface of the other substrate may be composed of an individual electrode group formed for each pixel.

For an image display medium having electrodes, leads are connected to the electrodes, and the leads are desirably provided in a non-image display area having a partition wall or the like.

The developer contained in the developer accommodating cell has at least two kinds of different charge polarities and different optical reflection densities (in other words, “different contrast” or “different color”). It is preferable to include dry developing particles. As typical examples, positively chargeable (or negatively chargeable) black particles having light absorbency and negatively chargeable (or positively chargeable) white particles having light reflectivity can be given.

One of the at least two types of developing particles constituting the dry developer may be non-conductive particles. In this case, regardless of whether the image display medium has an electrode or not, the presence of such non-conductive particles allows the two types of developing particles to be easily and reliably triboelectrically charged, and thus provides a good image display. Can be performed.

At least one of the at least two types of developing particles constituting the dry developer is a magnetic developing particle. When the magnetic developing particles are employed in this manner, a magnetic stirring force can be applied to the dry developing particles by a magnetic field in driving the developing particles by the electrostatic field, whereby the developing particles can be smoothly moved by the electrostatic field for image display. Easier to move,
It is possible to further improve the contrast and drive at a lower voltage.

As will be described later, a magnetic stirring force can be applied to the developer before displaying an image, thereby enabling initialization processing such as erasing the previous image.

The stirring of the developer for triboelectric charging of the developing particles contained in the medium can be performed by applying an oscillating magnetic field, applying mechanical vibration, irradiating an ultrasonic wave, or combining two or more of these. .

It should be noted that one type of developing particles may be both non-conductive particles and magnetic particles.

In any case, if the developing particles are too small, the adhesive force becomes extremely large, causing sticking between the developing particles and lowering the developing efficiency. On the other hand, if the developing particles are too small, the charge amount of the particles becomes very large, so that an electric field for moving the particles in displaying an image must be made large, and therefore a high driving voltage is required.

If the size of the developing particles is too large, triboelectric charging cannot be performed well, and a sufficient moving speed of the developing particles cannot be obtained in an electrostatic field for displaying an image, or good contrast cannot be obtained.

In light of these facts and materials for obtaining developing particles having predetermined characteristics, it is appropriate that the non-conductive developing particles have a particle size of 1 μm to 50 μm, and the magnetic developing particles have a particle size of 1 μm to 100 μm. .

The developing particles can be formed from, for example, a binder resin, a colorant, or the like, or a colorant alone.
The following can be used for these. -There is no particular limitation as long as it can disperse a binder resin colorant, a magnetic substance, and the like, and are usually used as a binder. A typical example is a binder resin used for an electrophotographic toner.

For example, polystyrene resin, poly (meth) acrylic resin, polyolefin resin, polyamide resin, polycarbonate resin, polyether resin, polysulfone resin, polyester resin, epoxy resin, urea resin, urethane Resin, urea resin, fluorine resin, silicon resin and copolymers thereof,
A block polymer, a graft polymer, a polymer blend, or the like can be used.

The glass transition point Tg may be quite high,
In some cases, it need not be a thermoplastic resin. -Colorant As the colorant, various organic or inorganic pigments and dyes as shown below can be used.

Examples of the black pigment include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon and the like.

Examples of the yellow pigment include graphite, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navels yellow, naphthol yellow S, banza yellow G, banza yellow 10G, benzidine yellow G, and benzidine. Yellow GR,
There are quinoline yellow lake, permanent yellow NCG, tartrazine lake and the like.

Examples of the orange pigments include red yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, indaslen brilliant orange RK, benzidine orange G, and indaslen brilliant orange GK.

Examples of red pigments include red iron, cadmium red, leadtan, mercury sulfide, cadmium, permanent red 4R, lithol red, pyrazolone red, watching red, calcium salt, lake red D, brilliant carmine 6B, eosin lake, and rhodamine. Lake B, Alizarin Lake, Brilliant Carmine 3B and the like.

The violet pigment includes manganese violet, fast violet B, methyl violet lake and the like.

As blue pigments, navy blue, cobalt blue, alkali blue lake, Victoria blue lake,
Phthalocyanine blue, metal-free phthalocyanine blue,
Phthalocyanine blue partially chlorinated products, Fast Sky Blue, Indaslen Blue BC and the like.

The green subjects include chrome green, chromium oxide, pigment green B, malachite green lake, final yellow green G, and the like.

As white pigments, zinc white, titanium oxide,
Examples include antimony white and zinc sulfide.

The extender includes baryte powder, barium carbonate, clay, silica, white carbon, talc, alumina white and the like.

Various dyes such as basic, acidic, disperse, and direct dyes include nigrosine, methylene blue, rose bengal, quinoline yellow, and ultramarine blue.

These colorants can be used alone or in combination.

Particularly in black and white display, carbon black is preferred as a black colorant, and titanium dioxide is preferred as a white colorant.

In particular, when a white pigment is kneaded with a molten binder resin (binder resin) to obtain a developing particle from the kneaded product, the amount of the white pigment used is determined in order to obtain a sufficient whiteness. To 100 parts by weight of the starting monomer
The amount is desirably 0 parts by weight or more, preferably 20 parts by weight or more, and is desirably 60 parts by weight or less, preferably 50 parts by weight or less in order to ensure sufficient dispersibility of the white pigment. When the amount of the white pigment exceeds 60 parts by weight, the binding property between the pigment and the binder resin and the dispersibility of the pigment deteriorate. On the other hand, when the amount of the white pigment is less than 10 parts by weight, sufficient development particles of other colors cannot be obtained. No concealing properties are obtained.

[0096] Carbon black is preferable as the black colorant. However, in the case where the developing particles are made to have magnetism, magnetic particles such as magnetite and ferrite and magnetic fine particles can be used as the colorant. -Other internal additives As internal additives preferably used other than the binder resin and the colorant, a magnetic substance, a charge control agent, a resistance adjuster and the like can be mentioned. -Charge control agent The charge control agent is not particularly limited as long as it gives charge to the developing particles by triboelectric charging.

Examples of the positive charge control agent include a nigrosine dye, a triphenylmethane compound, a quaternary ammonium salt compound, a polyamine resin, and an imidazole derivative.

Examples of the negative charge control agent include salicylic acid metal complexes, metal-containing azo dyes, oil-soluble dyes containing gold (including metal ions and metal atoms), quaternary ammonium salt compounds, calixarene compounds, and boron-containing compounds. (Boron benzylate complex), nitroimidazole derivatives and the like.

In addition, metal oxides such as ultrafine silica, ultrafine titanium oxide and ultrafine alumina, nitrogen-containing cyclic compounds such as pyridine and derivatives and salts thereof, various organic pigments,
Resins containing fluorine, chlorine, nitrogen and the like can also be used as charge control agents.・ Magnetic substance Magnetic particles and magnetic fine powder can be used for the production of magnetic developing particles. Examples thereof include ferromagnetic elements and alloys and compounds containing these, such as magnetite, hematite, and ferrite. Any known magnetic materials such as alloys and compounds such as iron, cobalt, nickel and manganese, and other ferromagnetic alloys may be used. The shape of these magnetic powders is various, such as a granular shape, a needle shape, and a flake shape, and can be appropriately selected and used. -Resistance adjuster As the resistance adjuster, there are also the same as the above-mentioned magnetic powders and colorants, and it is preferable to use metal oxide, graphite, carbon black, etc. in various shapes such as flake, fiber, powder, etc. Can be.

Next, a production example of the developing particles will be described.

From the binder resin, magnetic powder, colorant, charge control agent, resistance adjuster, and other additives as described above, necessary materials are selected, and after sufficiently mixing them by a predetermined amount, pressurization is performed. Heat kneading with a kneader or a twin-screw kneading device etc.
After cooling, it is roughly pulverized by a hammer mill, a cutter mill or the like. Next, after further pulverizing with a jet mill, an ong mill or the like, the particles are classified using an air classifier or the like until the particles have a predetermined average particle size, thereby obtaining developed particles.

By mixing and stirring the thus obtained particles having different charging polarities and different contrasts (optical reflection densities) at a predetermined ratio, a developer having a predetermined charge amount can be prepared. At this time, a third component (particle) such as a fluidity improver may be added and mixed. -About such fluidizers As fluidity improvers, for example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite Diatomaceous earth, chromium oxide, cerium oxide, red iron oxide, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride and the like.

In particular, fine powders such as silica, aluminum oxide, titanium dioxide and magnesium fluoride are preferable, and a fluidizing agent may be added alone or in combination.

As described above, the formation of an electrostatic field with respect to the developing particles on the reversible image display medium is intended to be displayed on the surface of one of the two substrates (for example, the substrate on the image observation side). An electrostatic latent image corresponding to an image can be formed, or an electrostatic latent image can be formed close to the electrostatic latent image based on the electrostatic latent image. In this case, the formation of the electrostatic field
It may be performed simultaneously with the formation or proximity of the electrostatic latent image, or may be performed after the formation of the electrostatic latent image. The formation of the electrostatic field can be performed, for example, by setting a predetermined potential for forming the electrostatic field on the substrate opposite to the substrate on which the electrostatic latent image is formed. The setting of the predetermined potential can be performed by, for example, applying a bias to the opposite substrate or setting the substrate to the ground potential.

The electrostatic latent image may be formed directly on the medium surface (substrate surface) using, for example, a direct electrostatic latent image forming apparatus, or may be formed outside the medium using an external electrostatic latent image forming apparatus. The electrostatic latent image may be formed by transferring the image onto the medium surface (substrate surface). The electrostatic latent image formed outside the medium using the external electrostatic latent image forming apparatus may be brought close to the medium surface (substrate surface).

As the direct electrostatic latent image forming apparatus, various discharge-type electrostatic latent image forming apparatuses which discharge an electrostatic latent image charge on the medium surface in accordance with an image to be displayed are to be displayed. Various charge-injection-type electrostatic latent image forming apparatuses that charge an electrostatic latent image by injecting a charge into a medium surface according to an image can be exemplified. Examples of the former include an ion flow type device and a multi-stylus type device having an electrostatic recording head in which recording electrodes are arranged in a predetermined direction (for example, a main scanning direction when a substrate is scanned by the device). As an example of the latter, a multi-stylus type device having an electrostatic recording head in which recording electrodes are arranged in a predetermined direction (for example, a main scanning direction when a substrate is scanned by the device) and adjacent control electrodes are arranged adjacent to the recording electrodes. Can be mentioned.

An external electrostatic latent image forming apparatus forms an electrostatic latent image corresponding to an image to be displayed on an electrostatic latent image carrier, and forms the electrostatic latent image on the electrostatic latent image carrier. Is transferred or brought close to the substrate surface. More specifically, an electrostatic latent image corresponding to an image to be displayed is formed on a photoconductor such as a photoconductor, and the electrostatic latent image on the photoconductor is transferred to or close to the substrate surface. And an electrostatic latent image corresponding to an image to be displayed on a dielectric, and the electrostatic latent image on the dielectric is transferred to or brought close to the substrate surface.

In displaying an image, an image forming section in the form of an electric field forming apparatus including any of the electrostatic latent image forming apparatuses can be employed.

Note that for a reversible image display medium having a counter electrode, an electrostatic field for image display can be formed by applying a voltage between the counter electrodes. An electric field forming device for this medium will be exemplified later.

The formation of an electrostatic field with respect to the developing particles in a reversible image display medium without electrodes or a medium having electrodes only on one substrate is performed by arranging electrodes on the outer surface of the medium and applying a voltage via the electrodes. Can also be applied.

Regardless of whether a reversible image display medium with or without electrodes is used, an apparatus for initializing the reversible image display medium such as erasing the previously displayed image before displaying the image is provided. Can be provided.

The initialization processing is performed by, for example, forming an electric field for moving the developing particles constituting the developer contained in the image display medium, applying a stirring force to the developer, or both. I can do it. The application of stirring power
For example, it can be performed by applying an alternating electric field to the developer, applying an oscillating magnetic field, irradiating ultrasonic waves, applying mechanical vibration, or combining these.

Therefore, the image forming apparatus includes, as an initialization apparatus, for example, one comprising an electric field forming apparatus for forming an electric field for moving the developing particles, one comprising a stirrer for applying a stirring force to the developing particles, A device including both a device and a stirring device can be appropriately employed.

For example, under the electric field, one of the two types of developing particles having the same optical reflection density (in other words, “same contrast” or “same color”) is transferred to one substrate side. By collecting and developing the other developing particles having the same optical reflection density on the other substrate side, the image can be erased, and when a new image is formed next time, the developing particles only need to be moved only in the image area. Because it ’s good
As a result, image display is performed smoothly, reliably, and with high quality.

For example, when the developer (developing particles) is stirred before the image is displayed, the image is erased and the generation of an afterimage is suppressed. In addition, the uneven distribution of the developing particles in the medium and the distribution are uniformed. Is achieved and a good charged state of the developing particles is obtained. As a result, high-quality images can be displayed in the subsequent image formation.

An initialization device composed of an electric field forming device for initializing an image display medium includes a pair of electrodes (usually metal) or a dielectric placed with a reversible image display medium interposed therebetween, and a bias voltage applied thereto. And a power supply device for applying the voltage.

In addition, various discharge type electric field forming devices for forming an electric field by discharging to an image display medium, and various charge injection type electric field forming devices for forming an electric field by injecting charges into a reversible image display medium are exemplified. it can. Examples of the former include a corona charging device, an ion flow type electric field forming device, and a multi-stylus type electric field forming device having a head in which electrodes are arranged in a predetermined direction. As the latter example, electrodes are arranged in a predetermined direction. And a multi-stylus type electric field forming apparatus having a head in which adjacent control electrodes are arranged adjacent to the electrodes.

As an initialization device comprising a stirring device,
The following can be exemplified. A device for applying an alternating electric field to a reversible image display medium. A device for applying an oscillating magnetic field to a reversible image display medium. A device that irradiates a reversible image display medium with ultrasonic waves. A device that applies mechanical vibration to a reversible image display medium. A device combining two or more of the above devices.

The initialization device for applying the oscillating magnetic field and the initialization device for applying the alternating electric field can efficiently agitate the developer.

Focusing on the image formation itself, when an image display medium without electrodes or an image display medium having electrodes only on one substrate is adopted, for example, the image to be displayed on the surface of the image display medium (substrate surface) is used. Developer for forming an electrostatic latent image corresponding to image forming an electrostatic field for image display simultaneously with or after the formation of the electrostatic latent image based on the electrostatic latent image May be stirred.

For an image display medium having a counter electrode, a voltage may be applied between the electrodes to form an electrostatic field, and the developer may be stirred simultaneously with the formation of the electrostatic field.

As described above, when the developer is stirred in the image formation (image display) itself, the developing particles move smoothly, so that the contrast can be further improved, the driving voltage can be further reduced, and high-speed image display can be performed.

As for the stirring of the developer in the image formation itself, the same method and apparatus as those of the stirring method and stirring apparatus exemplified in relation to the medium initialization processing can be employed.

When an electrostatic latent image is formed on the surface of the image display medium (substrate surface) in displaying an image, the surface of the medium is uniformly charged to a predetermined potential before the formation of the electrostatic latent image. An electrostatic latent image corresponding to the image to be displayed may be formed. Then, based on the electrostatic latent image, a predetermined electrostatic field corresponding to an image to be displayed on the developer particles in the developer accommodating cell may be formed to move the developer particles to display an image.

The electrostatic latent image on the medium is formed, for example, directly on the surface of the medium charged in the above-described charging step, or by forming the electrostatic latent image formed on the electrostatic latent image carrier outside the medium. It can be formed by transferring and forming on the surface of the medium charged in the charging step.

Even if the charge polarity of the area of the electrostatic latent image formed on the medium is the same as the charge polarity of the charge area by uniform charging of the medium surface prior to the formation of the electrostatic latent image, The polarity may be different, or 0 [V].

When the surface of the image display medium is uniformly charged to a predetermined potential in advance and an electrostatic latent image is written in the charged area, the charged developing particles in the developer storage cells can be moved. . Further, an electrostatic field sufficient to hold the moved developing particles at that position is formed. In other words, if the surface of the image display medium is uniformly charged to a predetermined potential in advance, and then the electrostatic latent image is written in the charged area, the image holding property is improved. This is particularly advantageous in terms of image retention when using a highly fluid developer or a developer whose fluidity is increased by a developer stirring process prior to image display. As a result, a high-quality image with excellent contrast can be stably displayed for a long time.

According to the various reversible image display media described above, a high-contrast, high-resolution, high-quality image can be stably displayed over a long period of time. Further, afterimages are less likely to occur, and therefore, good reversibility is exhibited. In this respect, a high-quality image can be displayed. Further, it is possible to display images at a higher speed, and it is also possible to reduce the driving voltage.

Hereinafter, specific examples of the developing particles and the developer will be described, and specific examples of a reversible image display medium, an image display method, an image forming apparatus, and the like will be described with reference to the drawings. <Developing Particles and Developer> White developing particles WP 100 parts by weight of a thermoplastic polyester resin (softening point 121 ° C., glass transition point 67 ° C.), 40 parts by weight of titanium oxide (CR-50, manufactured by Ishihara Sangyo Co., Ltd.) Zinc salicylate complex (Orient Chemical: Bontron E) as a negative charge control agent
-84) 5 parts by weight were sufficiently mixed with a Henschel mixer, kneaded with a twin-screw extruder, and then cooled. The kneaded product was coarsely pulverized, then pulverized by a jet pulverizer, and classified by wind power to obtain a white fine powder having a volume average particle size of 12 μm. Thereafter, 0.3 parts by weight of hydrophobic silica fine particles (manufactured by Nippon Aerosil Co., Ltd .: Aerosil R-972) were added to the white fine powder,
The mixture was mixed with a Henschel mixer to obtain white developed particles WP. Black developing particles BP Styrene-n-butyl methacrylate resin (softening point 13
100 parts by weight of carbon black (Lion Oil & Fat Co., Ketjen Black) 2
Parts by weight and silica (# 200 manufactured by Nippon Aerosil Co., Ltd.)
1.5 parts by weight and magnetite magnetic powder (RB-BL
After 500 parts by weight (Titanium Industry Co., Ltd.) were sufficiently mixed with a Henschel mixer, the mixture was kneaded with a vented twin-screw kneader.

The kneaded product was cooled, coarsely pulverized by a feather mill, finely pulverized by a jet mill, and classified by an air classifier to obtain black magnetic particles BP having a volume average particle diameter of 25 μm. Preparation of Developer DL 30 g of the white particles and 70 g of each black particle were placed in a polyethylene bottle, and rotated by a ball mill base to obtain 30 g.
Mixing and stirring were performed for a minute to obtain a developer. The white particles were negatively charged and the black particles were positively charged. <Reversible Image Display Medium> Reversible Image Display Medium 11 FIGS. 1 and 2 show an example of a reversible image display medium. FIG.
The medium 11 shown in FIG. 2 includes a first substrate 111 and a second substrate 112. These substrates 111 and 112 face each other with a predetermined gap therebetween. Substrate 11
Partitions 113 are provided between 1 and 112, and a predetermined gap between the two substrates is secured by these partitions 113. That is, the partition 113 is formed of both substrates 111,
Also serves as a spacer between 112. Also, both substrates 111,
112 are connected and fixed to each other by a partition 113.

The first substrate 111 is a transparent substrate, and is formed of, for example, a light transmitting plate such as a transparent glass, a transparent resin film, or the like. This substrate 111 is a substrate on the image observation side.

The partition 113 is also provided with a developer containing cell 116.
(See FIG. 3). That is, the partitions 113 are formed upright on the inner surface of the first substrate 111 in a grid pattern as shown in FIG.
A plurality of developer accommodating cells 116 are formed in a rectangular shape with a part of 13 as a partition wall.

Each partition wall has a width α and a height h, and the interval between adjacent partition walls is pt.

On the inner surface of the first substrate 111, the first electrode 11
4 are formed. The first electrode 114 is a transparent electrode in which a plurality of individual electrodes 114a are arranged in a grid pattern. Each individual electrode is formed of, for example, a transparent ITO film. The individual electrodes 114 a are arranged in each of the cells 116 at substantially the same interval as the thickness α of the wall 113. That is, here, one cell corresponds to one pixel.

The second substrate 112 is not necessarily required to be transparent, but is formed of, for example, a light-transmitting plate such as a transparent glass, a resin film, or the like.

The second electrode 115 is provided on the inner surface of the second substrate 112 facing the first substrate 111. Second electrode 1
Reference numeral 15 is continuous over the entire image display area on the inner surface of the substrate 112. The second electrode 115 is not necessarily a transparent electrode, but may be, for example, indium tin oxide (ITO).
It may be formed on a transparent electrode formed as described above.

Further, a dry developer DL containing white developing particles WP and black developing particles BP triboelectrically charged in each cell.
Is housed.

Each cell is sealed, and the developer DL does not leak from the cell.

The first electrode 1 on the image display medium 11
As shown in FIG. 4, the individual electrodes 114a constituting the semiconductor device 14 are connected to lead portions 110, respectively, and are connected to the electrode selection circuit 117 via these lead portions as shown in FIG.
Connected to. A positive drive voltage generation circuit 118a, a negative drive voltage generation circuit 118b, and a display data control unit 119 are connected to the electrode selection circuit 117. A drive voltage is applied to each of the individual electrodes 114a independently from the electrode selection circuit 117, and a display data control unit 119 is provided with display data output means (not shown, such as a computer, a word processor, and a facsimile). Machine)
The display data is input from the controller and the electrode selection circuit 117 is controlled based on the display data. In other words, these electrode selection circuits and the like constitute an example of an electric field forming apparatus or an image forming apparatus for a reversible image display medium having a counter electrode.

Thus, the bias voltage is applied to the second electrode 115 of the image display medium 11 as, for example, a ground electrode or, if necessary, from a bias power supply (not shown) to the electrode 115, and the second electrode 115 is connected to each of the individual electrodes 114a. In the meantime, a predetermined voltage is applied from the positive drive voltage generation circuit 118a or the negative drive voltage generation circuit 118b via the electrode selection circuit 117 which is controlled so that a desired image is displayed by the display data control unit 119, A predetermined electric field is formed for each pixel. Thus, as shown in FIG.
At L, the developing particles WP and BP move from the state where the developing particles are mixed as shown in FIG. 2 according to the electric field.

According to the medium 11, an image can be displayed, for example, as shown in FIG. In FIG. 5, Bk is a black display portion, and W is a white display portion.

The magnetic stir force applying device IN1 including the magnet plate MG1 and its driving device DR1 shown in FIG. 2 will be described later.

In this specification, the term “magnet plate” is used.
In this case, the “plate” includes various types such as those having high rigidity, those having flexibility, those having a thin sheet shape, and the like. -Reversible image display medium 12, 12 'FIG. 6 shows another example of the reversible image display medium.

The reversible image display medium 12 shown in FIG.
In the medium 11 shown in FIG. 1, at least the first substrate 111 is formed of a material having a light transmitting property and an insulating property, and the individual electrodes 114a are omitted.

The other points are the same as the medium 11 shown in FIG. In FIG. 6A, the same components and portions as those of the medium 11 are denoted by the same reference numerals as those of the medium 11.

The reversible image display medium 1 shown in FIG.
2 ′ is at least the second in the medium 11 shown in FIG.
The substrate 112 is formed of a material having both light transmittance and insulating properties, and the electrode 115 is omitted. In the medium 12 ', the substrate 112 is an image observation side substrate.

The other points are the same as the medium 11 shown in FIG. In FIG. 6B, the same components and parts as those of the medium 11 are denoted by the same reference numerals as those of the medium 11.

According to the medium 12 (or the medium 12 ′), for example, the electrode 115 of the second substrate 112 (the electrode 114 a for the medium 12 ′) is used as the ground electrode, and the first substrate 111 (the medium 12 ′ is the second electrode). A) arranging an electrode on the outer surface of the substrate 112) and selectively applying a voltage corresponding to an image to be formed between the electrode and the ground electrode;
b) directly forming an electrostatic latent image corresponding to the image to be formed,
c) The image carrier on which the electrostatic latent image corresponding to the image to be formed is formed is brought into contact (including proximity), and the image is displayed by applying a developing particle driving electric field to the developer DL based thereon. be able to.

The electrode 115 for the medium 12 and the electrode 114a for the medium 12 'are preferably electrodes having an intermediate resistance value. -Reversible image display medium 13 FIG. 7A shows another example of the reversible image display medium.

The reversible image display medium 13 shown in FIG.
In the medium 11 shown in FIG. 1, at least the first substrate 111 is formed of a material having a light transmitting property and an insulating property, and a first substrate electrode 114 and a second substrate electrode 115 are formed.
Is omitted.

The other points are the same as the medium 11 shown in FIG. 7, the same components and parts as those of the medium 11 are denoted by the same reference numerals as those of the medium 11. -Reversible image display medium 14 FIG. 8A shows another example of the reversible image display medium.

The reversible image display medium 14 shown in FIG.
In the medium 11 shown in FIG. 1, at least the first substrate 111 is formed of a material having a light transmitting property and an insulating property, and a first substrate electrode 114 and a second substrate electrode 115 are formed.
And a partition 113 composed of a plurality of partition walls 113a extending in parallel with the longitudinal side of the medium 14 is employed instead of the lattice-shaped partition (see also FIG. 9). A developer accommodating cell 116 is provided between each adjacent partition wall 113a. Each cell 116 has a developer D containing white developer particles WP and black developer particles BP frictionally charged with each other.
L is accommodated.

At the periphery of the medium 14, both substrates 111,
112 is heat-sealed to form a sealing portion 140. A portion 140a of the sealing portion 140, which is provided at both ends in the longitudinal direction of the vertical partition wall 113a and seals both ends of each cell, also serves as a partition wall forming the cell 116.

As shown in FIG. 9, each partition wall 113a has a width α and a height h, and the interval between adjacent partition walls 113a is pt.
It is formed as.

According to the media 13 and 14, for example, a) an electrostatic latent image corresponding to an image to be formed is directly formed on the first substrate 111, and b) an electrostatic latent image corresponding to an image to be formed is formed. An image can be displayed by bringing the image carrier into contact with (including proximity to) the first substrate 111 and applying a developing particle driving electric field to the developer DL based on the contact. The second substrate 112 may be set to a ground potential or the like as necessary. -Reversible image display medium 15, 15 'FIG. 10 shows another example of the reversible image display medium.

The reversible image display medium 15 (1) shown in FIG.
5 ′) is a medium 13 (14) in which a conductive film 112A is provided on the outer surface of the second substrate 112.

The other points are the same as the medium 13 (14). In FIG. 10, the same components as the medium 13 (14),
Parts are given the same reference numerals as the medium 13 (14).

The image display using the mediums 15 and 15 ′ is performed by, for example, setting the conductive film 112 A to an appropriate potential such as a ground potential, and a) forming an electrostatic latent image corresponding to the image to be formed on the first substrate 1.
B) an image carrier on which an electrostatic latent image according to an image to be formed is formed is brought into contact with (including proximity to) the first substrate 111, and the developer particles are added to the developer DL based thereon. An image can be displayed by applying a driving electric field.

It is to be noted that, instead of providing the conductive film 112A, the second substrate 112 may be a substrate having a conductive material dispersed therein.
This may be set to the ground potential.

As described above, according to each image display medium described with reference to the drawings, image display and image deletion can be repeated. Further, the developing particles WP and BP are contained in the cell, and do not require an external developer supply. Thus, the use of consumables such as a medium such as paper and a developer related to image display in the related art can be significantly suppressed. Further, since image energy does not require heat energy for fusing the toner to the medium as in the related art, the image forming energy can be reduced accordingly. Therefore, it is possible to meet today's environmental load reduction.

Since each of the media 11 to 15 'employs the dry developer DL containing the developing particles WP and BP having different colors, one of the developing particles BP (or BP) is used for the other developing particles BP (or BP). Or WP), the degree of concealment is good, and an image can be displayed with good contrast.

The developing particles W contained in the cell 116
P and BP are frictionally charged to different charging polarities,
In the image display, it is easy to move due to the Coulomb force, and in this regard, the image can be displayed with good contrast, the afterimage of the previous display hardly occurs, the image can be displayed at a high speed, and the driving at a low voltage is possible.

Further, since the dry developer DL is employed as the developer, sedimentation and agglomeration of the developing particles hardly occur.
As a result, a decrease in contrast in image display is small and stable image display can be performed for a long period of time. Since the sedimentation and aggregation of the developing particles hardly occur, the afterimage of the previously displayed image is hardly generated. Since the dry developer DL has little change with time, stable image display can be performed for a long time in this respect as well.

[0164] Any of the media 11 to 15 'can display images with higher resolution than conventional electrophoretic displays and the like. In other media except the medium 11, since the resolution does not depend on the size of the pixel electrode 114a unlike the medium 11, an image can be displayed at a higher resolution.

Also, any of the image display media 11 to 15 ′
Even when an image is formed by using an image forming method, prior to displaying an image on an image display medium (before the image displaying step), in displaying the image (in the image displaying step), or in any of the image displaying step and the image displaying step Also, an external magnetic field can be applied to the developer DL in the image display medium to exert a stirring force on the developer. For example, medium 11
In contrast, a magnetic stirring force applying device IN1 illustrated in FIG. 2 can be used.

That is, prior to the image display, the medium 11
The developer D in the medium is reciprocally oscillated in parallel with the medium 11 by the driving device DR1 on the magnet plate MG1 having the N-pole and the S-pole alternately arranged below the second substrate 112.
When an oscillating magnetic field is applied to L, the developer DL containing the magnetic developing particles BP is agitated, and when a previous image is present, the image is erased to suppress the occurrence of afterimages. And uniform distribution can be achieved, and a good charged state of the developing particles can be obtained. Thus, high-quality image display can be performed thereafter.

The electrodes 114a and 11a facing each other
5 and a reciprocating vibration of the magnet plate MG1 by applying a voltage for image display between the
Applying an oscillating magnetic field to L and exerting a magnetic stirring force on the developer DL containing the magnetic developing particles BP, thereby making the developing particles easy to move, and displaying a high-quality image at high speed, low voltage driving, and so on. Can be.

When an image is displayed by applying a voltage between the electrodes 114a and 115 facing each other as in the medium 11, it is not necessary to consider frictional charging between the magnet plate MG1 and the medium substrate. May contact.

For each of the media 12 to 15 ', the same advantage can be obtained by applying a stirring force to the developer DL using an appropriate magnetic stirring force applying device before and / or during image display.

Next, the media 12, 12 ', 13, 14, 1
An example of displaying an image using 5, 15 'will be described together with an image forming apparatus.

The image forming apparatus shown in FIG. 11A includes a photosensitive drum PC that is driven to rotate in the direction of the arrow in the figure. A scorotron charger CH, a laser image exposing device EX, an eraser lamp IR are provided around the photosensitive drum PC.
Is arranged. An electrode roller R1 that is driven to rotate is disposed below the photosensitive drum PC. Electrode roller R1
Is a developing electrode roller for forming an electrostatic field for image display here. A bias voltage can be applied to the roller R1 from the power supply PW1. The roller R1 has a built-in rotary magnetic pole roller R2 that is driven to rotate (or reciprocates) in the opposite direction to the roller R1. The roller R2 is a kind of a magnetic field generating member, and applies an oscillating magnetic field to the developer in the image display medium to exert a magnetic stirring force when displaying an image. The roller R2 forms an example (IN2) of a magnetic stirring force applying device for image display.

The roller R1 in the image display medium transport direction
The rotating magnetic pole roller R3 is arranged on the further upstream side. The roller R3 is also a magnetic field generating member, and applies an oscillating magnetic field to the developer in the image display medium before displaying an image to exert a magnetic stirring force to initialize the medium. The roller R3 constitutes a magnetic stirring force applying device IN3 for before image display. In addition, on the upstream side of the roller R1, for example, the roller R3
Further downstream, a charger CRH (although not limited thereto, a corona charger here) for uniformly charging the surface of the image display medium to a predetermined potential before displaying an image may be provided.

In this image forming apparatus, the photosensitive drum PC
After the surface is charged by the charger CH, the charged area is image-exposed by the exposure device EX to form an electrostatic latent image EI on the drum PC. On the other hand, the power supply PW1
A bias is applied from. In some cases, the electrode roller R1 may be set to the ground potential.

Then, the electrostatic latent image EI on the photosensitive drum PC
For example, the medium 13 or 14 is fed between the drum and the electrode roller R1 in synchronization with the above. At this time, an oscillating magnetic field is applied to the developer DL in the medium 13 (14) by the rotating magnetic pole roller R3 to stir the developer and perform an initialization process such as erasing the previous image, or to further perform the medium 13 (14). )
Is uniformly charged in advance to a predetermined potential by the charger CRH.

The medium 13 (14) arriving in this way
As an electric field passes between the photosensitive drum PC and the electrode roller R1, an electrostatic field based on the electrostatic latent image EI is formed on the developing particles BP and WP of the developer DL contained in each cell 116. As a result, the developing particles move by Coulomb force acting between the electrostatic field and the charged developing particles. At this time, the developing particles in the medium are easily moved by the action of the oscillating magnetic field applied by the rotating magnetic pole roller R2.

FIG. 7B or FIG. 8B illustrates a state in which the black and white particles WP and BP are mixed in the developer DL as shown in FIG. 7A or FIG. 8A. As described above, the white particles WP and the black particles BP easily move according to the electric field. Thus, an image can be displayed with a predetermined contrast.

After the image is displayed as described above, the charge on the surface of the photosensitive drum PC is erased by the eraser lamp IR in preparation for the next print.

Instead of the magnetic pole roller R2, for example, as shown in FIG. 11B, a magnet plate MG2 may be arranged downstream of the photosensitive drum PC.

This magnet plate MG2 is a kind of a magnetic field generating member, and is another example of the magnetic stirring device (IN4).
Is composed.

The magnet plate MG2 is, as shown in FIG. 20 (shown as MG in FIG. 20), an image display medium (FIG. 2).
0 indicates D. (Cells are indicated by CEL.)
The poles and the S poles are alternately arranged. When the medium 13 (14) moves thereon, an oscillating magnetic field is applied to the developer in the medium to facilitate movement of the developing particles. The magnet plate MG2 may be stationary, but may be reciprocated in the medium transport direction.

Further, instead of the magnet plate MG2, the above-mentioned magnetic pole roller R2 may be disposed at substantially the same position. Magnetic pole roller R2 for image display and magnetic pole roller 3 for before image display
Is a magnetic pole roller of the type shown in FIG. 24 (indicated by RG in FIG. 24), in which N poles and S poles are alternately arranged in the roller rotation direction.

The magnet plate MG1 shown in FIG. 2, the magnet plate MG2, and the magnetic pole rollers R2, R3
Is a type of magnetic field generating member having magnetic poles arranged in the predetermined one direction when the relative movement direction between the surface of the magnetic field generating member and the reversible image display medium is a predetermined one direction.

When a magnet plate (eg, MG1 or MG2) is used, the magnetic developing particles BP in the image display medium
As shown in FIGS. 17 (A) to 17 (D) and FIG. 18 (A), the magnetic plate is attracted to one of the substrates in the image display medium, and tends to form a particle chain. Vibration is caused by the relative movement, whereby the developer is agitated.

In the case of the image forming apparatus shown in FIG. 11B, for example, an image can be displayed on the medium 13 (14) as follows.

That is, after the medium 13 (14) is initialized, an electrostatic latent image is transferred and formed on the surface of the medium 13 (14), and subsequently, the medium 13 (14) on which the electrostatic latent image is formed.
Is passed over the magnet plate MG2, whereby a target image can be finally displayed.

Developer particles BP, W in medium 13 (14)
Although it is difficult for P to move at the stage of forming the electrostatic latent image, P passes over the magnet plate MG2, in other words, the medium 13 (14) on which the electrostatic latent image is formed and the magnet plate MG2.
19A to 19C, the developer in each cell 116 is sequentially subjected to the magnetic stirring force, and an image is sequentially formed for each cell. .

Next, still another modification of the image forming apparatus shown in FIG. 11A will be described with reference to FIGS.

The image forming apparatus shown in FIG.
The image forming apparatus shown in FIG. 1B employs a magnet plate MG3 instead of the rotating magnetic pole roller R3 for displaying an image. The plate MG3 forms a magnetic stirring force applying device IN5. The other points are substantially the same as those of the image forming apparatus shown in FIGS. 11A and 11B.
In FIG. 15A, the same parts and components as those in the image forming apparatus shown in FIG.
The same reference numerals are given as in. Magnet plate M
G3 may be stationary, but may be reciprocally oscillated in the traveling direction of the medium 13 (14).

The image forming apparatus shown in FIG.
In the image forming apparatus of FIG. 5A, the magnet plate MG2 for the image display process is replaced with a belt-shaped magnetic field generating member MG4 that is driven to rotate.

The image forming apparatus shown in FIG.
In the image forming apparatus of FIG. 5A, a rotating magnetic pole roller R2 is incorporated in an electrode roller R1.

The image forming apparatus shown in FIG.
In the image forming apparatus of (A), in order to enhance the stirring effect of the developer, the magnet plates MG3 and MG3 'are made to face both surfaces of the image display medium 13 (14) before the image is displayed, and in the image display step. Are the magnet plates MG2 and M
G2 '.

The image forming apparatus shown in FIG.
In the image forming apparatus shown in FIG. 5B, the belt-shaped magnetic field generating member MG4 and the magnet plate MG2 'are made to face the medium 13 (14) in the image display step.

The image forming apparatus shown in FIG.
In the image forming apparatus shown in FIG. 5C, the magnet plates MG3 and MG3 'are provided on both surfaces of the medium 13 (14) before displaying the image.
And to face.

Each of the magnet plates MG2 'and MG3' may be stationary, but may be reciprocally oscillated in the traveling direction of the medium 13 (14).

When a magnetic field generating member such as a magnet plate faces both sides of the image display medium, the magnetic developing particles BP in the image display medium, as shown in FIG. Each of the substrates is slightly attracted, and vibrates with the relative movement between the magnetic field generating member and the image display medium in such a state that a particle chain is formed for each substrate, thereby causing the developer to move only on one surface of the medium. It is more agitated than if you are facing it.

Regarding a magnetic field generating member such as a magnet plate disposed so as to face both surfaces of the medium 13 (14),
The arrangement of the magnetic poles may be different from each other to further enhance the developer stirring effect.

Images of the media 12 and 12 'and the media 15 and 15' can be formed by the image forming apparatuses shown in FIGS. When forming an image on these, the medium 1
2, the pixel electrode 114a for the medium 12 ', and the conductive film 112A for the mediums 15 and 15', or a bias can be applied thereto.

The magnet plates MG2, MG used for the image display medium for displaying an image based on the electrostatic latent image
2 ′, MG3, MG3 ′, belt-shaped magnetic field generating member MG4
In particular, the magnet plates MG2 ′ and MG facing the substrate (insulating substrate) on the side on which the electrostatic latent image is formed
3 'is arranged away from the substrate to avoid unnecessary triboelectric charging with the substrate.

Next, another example of the magnetic pole arrangement of the magnet plate and the rotating magnetic pole roller will be described with reference to FIGS. 21 to 23 and 25.

FIGS. 21 to 23 show examples of magnetic pole arrangement of the magnet plate.

In the magnet plate MG shown in FIG. 21, when the relative movement direction between the surface of the magnet plate and the reversible image display medium D is a predetermined direction and a direction crossing the direction, the magnetic poles are arranged in the crossing direction. It was done. In this case, the magnet plate MG may be reciprocally oscillated in a direction Sw (for example, a direction perpendicular to) the transverse direction Fw of the reversible image display medium D relative thereto.

When the relative movement direction between the surface of the magnet plate and the reversible image display medium D is one predetermined direction, at least two rows of magnet plates MG in the direction crossing the predetermined one direction are provided. The magnetic poles are arranged, and the N pole position and the S pole position are shifted from each other in the direction of the magnetic pole row in the adjacent magnetic pole row. The magnet plate MG may be stationary, but a direction (for example, a direction orthogonal to) that crosses the relative traveling direction Fw of the reversible image display medium D with respect thereto (for example, a direction orthogonal to Sw).
May be reciprocated.

The magnet plate MG shown in FIG. 23 has a direction that forms a predetermined angle with respect to the predetermined direction when the relative movement direction between the surface of the magnet plate and the reversible image display medium D is defined as a predetermined direction. Are arranged with magnetic poles. The magnet plate MG may be stationary, but may be reciprocally oscillated in the relative traveling direction Fw of the medium D and / or in the direction (for example, orthogonal direction) Sw thereof.

FIG. 25 shows an example of magnetic pole arrangement of a rotating magnetic pole roller. The roller RG has magnetic poles arranged in a direction forming a predetermined angle with respect to the predetermined one direction when a relative movement direction between the roller and the reversible image display medium D is set to a predetermined one direction. is there. Band-shaped north poles and band-shaped south poles are alternately spirally arranged.

These magnet plates and magnetic pole rollers can also be used for either a magnetic stirring device for displaying images or a magnetic stirring device for displaying images.

Various magnetic pole arrangements can also be employed for the belt-shaped magnetic field generating member MG4 shown in FIG.

The image forming apparatus shown in FIG. 12 includes an ion flow type direct electrostatic latent image forming apparatus CR2. Device CR
2 is a corona ion generator c for generating corona ions
2 and corona ions generated in the generating section
3 (or 14) of the writing electrode e2 for leading to the surface of the first substrate 111, and a voltage for leading positive (or negative) corona ions to a pixel corresponding portion of the surface of the substrate 111 in accordance with an image to be displayed. A write electrode control circuit f2 for applying a voltage to the write electrode e2.

The corona ion generator c2 is provided in the shield case c21.
A corona wire c22 is formed by stretching a gold-plated tungsten wire having a diameter of 20 μm, and a positive (or negative) voltage (for example, 4 kV to 10 kV) is applied to this wire from a power source Pc2 to generate corona ions.

The write electrode e2 is connected to the medium 13 (or 1
4) The shield case c2 directed to the first substrate 111
1 and includes an upper electrode e21 and a lower electrode e22, through which a corona ion flow can pass.

The electrode control circuit f2 includes a control power supply Pc21,
Including a bias power supply Pc22 and a control unit f21,
The control unit f21 outputs an ion extraction voltage corresponding to the polarity of ions to be extracted toward the medium 13 to the electrodes e21 and e2.
2 can be applied.

Here, when a positive voltage is applied to the upper electrode e21 and a negative voltage is applied to the lower electrode e21 under the instruction of the control unit f21, positive corona ions can be guided to the medium (FIG. 12A). . When a negative voltage is applied to the upper electrode e21 and a positive voltage is applied to the lower electrode e21, positive corona ions can be confined (FIG. 12B).

Further, an electrode roller R1 is provided so as to face the writing electrode e2, and a bias voltage is applied to the electrode roller R1 from the power supply PW1, or the roller R1 is set to the ground potential. The roller R1 incorporates a magnetic pole roller R2 that is driven to rotate.

Thus, the surface of the medium 13 (or 14) is uniformly charged to a predetermined potential in advance by a charger such as a corona charger, and the medium 13 (or 14) thus pre-charged is moved relative to the apparatus CR2. Moving the electrode roller R1 in the medium feed direction and rotating the magnetic pole roller R2 in the opposite direction while moving the first substrate in accordance with the image to be displayed, under the instruction of the control unit f21. As shown in FIG. 12A, a positive corona ion is led to a predetermined pixel corresponding portion corresponding to an image to be displayed among a plurality of pixel corresponding portions on the surface of the surface 111, and FIG.
As shown in FIG. In this way, an image can be displayed on the medium 13 or 14 as illustrated in FIG. 7B or FIG. 8B.

[0214] Prior to the image display, any of the magnetic stir force imparting devices exemplified above may be used without any hindrance.

It is not always necessary to charge the surface of the medium 13 (14) in advance.

The discharge wire c2 in the device CR2
2 can be replaced by a solid discharge element.

Images can also be formed on the media 12, 12 'and the media 15, 15' by such an image forming apparatus. When an image is formed on these, the medium 12 is
5 for the medium 12 ′ and the electrode 114 a for the medium 12 ′.
For 5 and 15 ', the conductive film 112A is grounded,
Appropriate bias may be applied to these.

Further, the electrostatic latent image forming apparatus CR2 shown in FIG.
Uses the discharge phenomenon, but in addition to these devices,
Various discharge-type electrostatic latent image forming apparatuses can be used.

The image forming apparatus shown in FIG. 13 includes a multi-stylus type direct electrostatic latent image forming apparatus CR3. The device CR3 includes, for example, a multi-stylus head H3 having a plurality of electrodes e3 arranged in the main scanning direction with respect to the medium 15 (or 15 ′) and arranged close to the first substrate 111. A signal voltage is applied to apply an electrostatic latent image charge to a portion corresponding to a pixel on the surface of the first substrate 111 according to an image to be displayed on each electrode e3. Medium 15 (15 ')
For example, a bias is applied to the conductive film 112A of the second substrate 112, for example, or the conductive film 112A is grounded.
Then, the sheet is conveyed relatively to the head H3, whereby an image is displayed.

[0220] Prior to the image display, any of the magnetic stir force imparting devices exemplified above may be used without any problem.

Note that images can be formed on the mediums 12 and 12 'by this image forming apparatus. In that case, medium 1
A bias may be applied to the second electrode 115 or the electrode 114a of the medium 12 'as necessary.

Also, with respect to the media 13 and 14, an image can be formed by this image forming apparatus by bringing an external electrode to which a bias can be applied or grounded into contact with the outer surface of the second substrate 112 as necessary.

The image forming apparatus shown in FIG. 14 includes a charge injection type direct electrostatic latent image forming apparatus CR4. Device CR4
Is a multi-stylus type device having an electrostatic recording head H4 in which a plurality of recording electrodes e4 are arranged in the main scanning direction with respect to the medium, and adjacent control electrodes e41 are arranged adjacent to the recording electrodes e4. This head is arranged, for example, close to the medium, and a voltage of about の of the voltage (recording voltage) required for image recording is sequentially applied to the control electrode e41 of the head H4 sequentially, and the recording voltage of about 1 is applied to the recording electrode e4. By applying an image signal voltage of / 2, an electrostatic latent image can be formed on the medium located immediately below the recording electrodes.

Next, more specific examples of the reversible image display medium and image display using the same will be described. (Reversible image display medium D1) A medium of the same type as the reversible image display medium 14 shown in FIGS. 8 and 9 and formed as follows.

That is, a transparent PET (polyethylene terephthalate) film was formed by heating and pressing to form a plurality of continuous partition walls 113a on a 25 μm thick base portion corresponding to the first substrate 111. The wall thickness (width) α of the continuous partition wall 113a is 30 μm, the height h is 100 μm, and the interval pt between adjacent partition walls is 500 μm.

Next, the developer DL is applied to each of the continuous groove cells 116 between the adjacent partition walls on the substrate 111.
Was put. The developer was added so that the volume ratio of the developer contained to the volume of the continuous grooved cells was 30.

Next, the photocurable adhesive is thinly applied only to the top surface of the wall 113a on each substrate 111, and then the second substrate 11
2 as PET with 25 μm thickness carbon black
A film was adhered to the adhesive on its inner surface. The adhesive was cured by ultraviolet irradiation to bond the film.

Thereafter, the peripheral edges of the first and second substrates 111 and 112 were heat-sealed.

Thus, a medium D1 of the type shown in FIGS. 8 and 9 was obtained. (Image Display Using Medium D1) FIG.
An image was formed by the image forming apparatus of (A).

The surface of the photosensitive drum PC is uniformly charged to about -900 V by the charger CH.
Image exposure was performed from X, the surface potential of the exposed area was attenuated to about −50 V, and an electrostatic latent image EI was formed.

On the other hand, the medium D1 carried in is initialized by the magnet plate MG3, and the surface of the medium D1 is subsequently charged by the pre-image display charger CRH to a polarity opposite to the charging polarity of the photosensitive member surface. It was uniformly charged to + 400V.

Subsequently, the medium D1 was fed between the photosensitive drum PC and the counter electrode roller (transfer roller) R1 in synchronization with the electrostatic latent image EI on the photosensitive drum PC. A roller having a resistance of about 10 ⁸ Ω was used as the roller R1, and a transfer bias of about +1300 V was applied from the power supply PW1.

Thus, on the surface of the medium D1, the image part (black part) is about -300 V, and the background part (white part) is about + 300V.
An electrostatic latent image of about V was transferred and formed.

The medium D1 on which the electrostatic latent image is formed as described above
Is continuously passed above the magnet plate MG2 to exert a stirring action by the oscillating magnetic field on the developer DL in the medium containing the magnetic developing particles BP, thereby facilitating the movement of the developing particles and displaying an image.

Thus, a good image was obtained. (Reversible image display medium D2) A medium of the same type as the reversible image display medium with electrodes 11 shown in FIG. 1 and formed as follows.

That is, a photoresist was applied on the ITO film of the first substrate 111 made of a transparent PET (polyethylene terephthalate) film having a thickness of 50 μm and having a transparent ITO film formed on the entire surface. The photoresist was covered with a photomask having openings formed in a predetermined pattern, exposed from above, subsequently developed and etched, and the remaining photoresist was stripped off. As a result, a 1 mm × 1 mm square pixel electrode 114 a (see FIG. 4) is arranged in a grid pattern with an interval of 0.1 mm, and the first electrode 110 (see FIG. 4) is connected between the pixel electrodes. A pattern was formed.

The square electrode 114 on the first substrate 111
By repeatedly providing a resist on a thick film in portions other than a, a grid-like partition 113 (see FIG. 3) was formed. Partition wall 1
13 (thickness (width) α of each partition wall 113a)
= 0.1 mm, height h = 100 μm, wall interval pt = 1 m
m (corresponding to one side of the individual electrode 114a).

On the other hand, an ITO film was formed as a second electrode 115 on the entire surface of the second substrate 112 made of a transparent PET film having a thickness of 50 μm to a thickness of 500 ° by a sputtering method.

Then, the developer DL was put into each concave portion surrounded by the lattice-like wall 113 of the first substrate 111. The developer was added so that the volume ratio of the developer contained to the volume of the concave portion was 30%.

Next, a light-curing adhesive 119a (see FIG. 1) is applied thinly only on the top surface of the wall 113, and then the ITO electrode 115 side of the second substrate 112 is brought into close contact with the second substrate 112 to cure the adhesive by irradiating ultraviolet rays. Was.

Thereafter, the periphery of the first and second substrates 111 and 112 was sealed with an epoxy resin adhesive 119b (see FIG. 1).

Thus, a medium D2 of the type shown in FIG. 1 was obtained. (Image Display Using Medium D2) For the medium D2, the second electrode 11 was formed using the image forming apparatus shown in FIGS.
5 was set to the ground potential, and a negative voltage was applied to the individual electrode 114a corresponding to the pixel to be displayed in black, and a positive voltage was applied to the individual electrode 114a corresponding to the pixel to be displayed in white. In this way, an image is displayed by applying a voltage corresponding to the display data to each individual electrode 114a. Further, prior to the image display, the developer was initialized by vibrating the magnet plate MG1, and also in the image display, the developing particles were easily moved by vibrating the magnet plate MG1. Thus, a good image could be obtained.

Next, an experiment for confirming the effect of stirring the developer in the image display medium by the magnetic field generating member will be described.

In this experiment, the medium D1 was used, the medium was sandwiched between a pair of electrodes, and a magnet plate was arranged outside the substrate 112 on the side opposite to the image observation side. The magnet plate vibrates reciprocally in parallel with the substrate 112, and has magnetic poles of N pole and S pole alternately arranged in the vibration direction.

Each experiment was performed according to the following procedure (step 1 and step 2).
The number of magnetic poles passing through each part of the developer DL was changed using magnet plates having different magnetic flux densities with respect to 1. Step 1 With the electrode on the substrate 112 side opposite to the image observation side set to the ground potential, the electrode on the image observation side substrate 111 side is
200 V was applied, and the magnet plate was sufficiently reciprocated in parallel with the substrate 112. Thus, an image in which the black magnetic particles BP were unevenly distributed on the image observation side was obtained. When viewed from the image observation side, the entire image is a black image. Step 2 After Step 1, the electrode on the image observation side substrate 111 is +200 V while the electrode on the substrate 112 side is set to the ground potential.
Was applied, and a magnet plate of the same type and arranged similarly was reciprocally oscillated to display an image such that the white developing particles WP were unevenly distributed on the image observation side.

The developer stirring property was evaluated for each experiment. The evaluation was made based on the reflection density of the white portion viewed from the image observation side after step 2. When the maximum reflection density of the white portion is 0.4 or less and the difference between the maximum reflection density and the minimum reflection density of the white portion is 0.2 or less, it is visually good. The others were regarded as poor stirring properties (x).

For measuring the image density, use a reflection densitometer (manufactured by Konica Corporation).
Sakura DENSITMETER PDA-65) was used.

The evaluation results are shown in Table 1 together with the magnetic flux density of the magnet plate for the medium D1 and the number of passing magnetic poles for each part of the developer used in step 2.

[0249]

[Table 1]

Table 1 shows that in order for the developing particles to move smoothly, it is preferable that the magnetic flux density with respect to the medium is 50 gauss or more, and at least two magnetic poles pass through each part of the developer.

[0251]

As described above, according to the present invention, image display and image erasure can be repeatedly performed, so that image display media such as paper, developer,
It is possible to provide an image display method and an image forming apparatus that can reduce the use of consumables such as ink and can respond to today's reduction in environmental load.

Also, according to the present invention, high contrast
An image display method and an image forming apparatus capable of displaying a high-quality image can be provided.

Further, according to the present invention, image display is performed at a higher resolution than a conventional electrophoretic image display medium or twisted ball type image display medium, and based on an electrostatic latent image without using a counter electrode. If possible, it is possible to provide a reversible image display medium capable of displaying an image with higher resolution and higher quality.

Further, according to the present invention, it is possible to provide an image display method and an image forming apparatus which are less likely to cause an afterimage and can display a high quality image.

Further, according to the present invention, it is possible to provide an image display method and an image forming apparatus capable of displaying images at high speed.

Further, according to the present invention, it is possible to provide an image display method and an image forming apparatus which require a low drive voltage.

In particular, the image display method and the image forming apparatus according to the present invention use a reversible image display medium in which at least one type of developing particles among at least two types of encapsulated developing particles is magnetic developing particles. Before the image display step on the display medium and / or in the image display step, an external magnetic field is applied to the developer in the image display medium to exert a stirring force on the developer. When an agitation force is applied, the developer is agitated prior to image display, whereby the image is erased when there is a previous image, and the occurrence of an afterimage is suppressed, and the uneven distribution of each developing particle in the medium is suppressed and distributed. And a good charged state of the developed particles can be obtained, so that a high-quality image can be displayed in the subsequent image forming step. When exerting a magnetic stirring force to the developer in the display step, the motion of the developer particles to be moved by the application of an electrostatic field is smooth, the correspondingly high speed, low voltage driving, it is possible to display a high quality image.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an example of a reversible image display medium with a counter electrode before image display.

FIG. 2 is a cross-sectional view of the medium shown in FIG. 1 in an image display state.

FIG. 3 is a perspective view of a first substrate and a grid-like partition formed on the first substrate in the medium shown in FIG. 1;

FIG. 4 is a plan view of a first substrate and individual electrodes formed on the first substrate in the medium shown in FIG.

FIG. 5 is a diagram showing an example of image display on the medium shown in FIG. 1;

6A is a cross-sectional view of another example of the reversible image display medium, and FIG. 6B is a cross-sectional view of still another example of the reversible image display medium.

7A and 7B show still another example of the reversible image display medium. FIG. 7A is a cross-sectional view of the reversible image display medium before displaying an image, and FIG. It is sectional drawing of an example.

8A and 8B show still another example of the reversible image display medium. FIG. 8A is a cross-sectional view of the reversible image display medium before displaying an image, and FIG. It is sectional drawing of an example.

FIG. 9 is a plan view showing a part of the medium shown in FIG.

FIG. 10A is a sectional view of still another example of the reversible image display medium, and FIG. 10B is a sectional view of still another example of the reversible image display medium.

11A is a diagram showing a schematic configuration of an example of an image forming apparatus including an external electrostatic latent image forming apparatus, and FIG.
FIG. 1B is a diagram illustrating a part of a modification of the image forming apparatus in FIG.

FIG. 12 is a diagram showing a schematic configuration of an example of an image forming apparatus including an ion flow type direct electrostatic latent image forming apparatus.

FIG. 13 is a diagram illustrating a schematic configuration of an example of an image forming apparatus including a multi-stylus type direct electrostatic latent image forming apparatus.

FIG. 14 is a diagram illustrating a schematic configuration of an example of an image forming apparatus including a multi-stylus type electrostatic latent image forming apparatus having adjacent control electrodes.

FIGS. 15A to 15C are diagrams illustrating a schematic configuration of still another example of the image forming apparatus.

FIGS. 16A to 16C are diagrams each showing a schematic configuration of still another example of the image forming apparatus.

17 (A) to 17 (D) are diagrams schematically showing the movement of magnetic developing particles when an oscillating magnetic field is applied with a magnetic field generating member facing one surface of an image display medium.

FIG. 18A shows a state in which an oscillating magnetic field is applied with a magnetic field generating member facing one surface of an image display medium.
(B) is a diagram schematically showing the movement of the magnetic developing particles when an oscillating magnetic field is applied with the magnetic field generating members facing both surfaces of the image display medium.

FIGS. 19A to 19C are diagrams showing a state in which an oscillating magnetic field is applied to an image display medium having an electrostatic latent image formed on the surface to display an image.

FIG. 20 is a diagram showing an example of magnetic pole arrangement in a magnet plate.

FIG. 21 is a diagram showing another example of the magnetic pole arrangement in the magnet plate.

FIG. 22 is a view showing still another example of the magnetic pole arrangement in the magnet plate.

FIG. 23 is a view showing still another example of the magnetic pole arrangement in the magnet plate.

FIG. 24 is a diagram illustrating an example of a magnetic pole arrangement in a rotating magnetic pole roller.

FIG. 25 is a diagram showing another example of the magnetic pole arrangement in the rotating magnetic pole roller.

FIGS. 26A to 26E are diagrams showing examples of a developer accommodating cell in a reversible image display medium, respectively.

[Explanation of symbols]

Reference Signs List 11 reversible image display medium 111 first substrate 112 second substrate 113 partition 113a partition wall α partition wall thickness pt adjacent partition wall interval h partition wall height 114 first electrode 114a individual electrode (pixel electrode) 115th 2 electrode 116 developer storage cell 110 lead section 117 electrode selection circuit 118a positive drive voltage generation circuit 118b negative drive voltage generation circuit 119 display data control section DL developer WP white development particles BP black development particles Bk black display portion W white Display part 12, 12 ', 13, 14, 15, 15', D, D1
Reversible image display medium 140 Sealing part 140a Part of sealing part 120 112A Conductive film CEL Developer storage cell PC Photoconductor drum CH Scorotron charger EX Laser image exposure device IR eraser lamp R1 Electrode roller R2, RG Rotating magnetic pole roller PW1 Bias power supply CRH Charger MG Magnet plate CR2 Ion flow type direct electrostatic latent image forming device c2 Corona ion generator e2 Write electrode f2 Write electrode control circuit c21 Shield case c22 Corona wire Pc2 Power supply e21 Upper electrode e22 Lower electrode Pc21 Control Power supply Pc22 Bias power supply f21 Control unit CR3 Multi-stylus type direct electrostatic latent image forming apparatus e3 Electrode H3 Multi-stylus head CR4 Multi-stylus type electrostatic latent image forming apparatus having adjacent control electrodes e4 Electrode e41 Control electrode H4 Electrostatic recording head IN1 to IN5 Magnetic stirring force applying device MG, MG1, MG2, MG2 ', MG3, MG3' Magnet plate (magnetic field generating member) DR1 Drive device for magnet plate MG1 MG4 Belt-shaped magnetic field generation Element

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akihito Ikebe 2-3-113 Azuchicho, Chuo-ku, Osaka-shi, Osaka Inside Osaka International Building Minolta Co., Ltd. (72) Inventor Masaharu Kanazawa Azuchi, Chuo-ku, Osaka-shi, Osaka Osaka International Building Minolta Co., Ltd., 2-313 Machi (72) Inventor Nozomi Yome 2-3-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka Osaka International Building Minolta Co., Ltd. (72) Inventor Kurita Takaharu 5-2232-3-2-1 Sayama, Osaka Sayama City, Osaka Prefecture F term (reference) 5C094 AA02 AA06 AA44 AA53 BA09 BA75 BA76 BA82 BA84 BA87 BA93 CA19 CA23 EA04 EA05 EA07 EB02 EC04 FB12 FB15 FB16

Claims (16)

[Claims] 1. Two or more substrates facing each other at a predetermined gap, one or two or more developer storage cells formed between the two substrates and surrounded by a partition wall. And a dry developer encapsulated in a cell, wherein the dry developer has at least two types of dry developing particles having triboelectric charging properties having different charging polarities and different optical reflection densities. Preparing a reversible image display medium, wherein at least one of the at least two types of developing particles is a magnetic developing particle; and triboelectrically charging the reversible image display medium to opposite polarities. Applying an electrostatic field corresponding to an image to be formed on the developed developing particles to drive the developing particles to display an image, and before the image displaying step and / or in the image displaying step, Said reversible Image display method and performing a magnetic stirring force imparted on the stirring force by the action of an external magnetic field to the developer of the image display medium developer. 2. The method according to claim 1, wherein the magnetic stir force is applied by causing a magnetic field generating member to face the reversible image display medium and relatively moving the image display medium and the surface of the magnetic field generating member to reduce the magnetic field intensity applied to the developer. 2. The image display method according to claim 1, wherein the method is performed by vibrating. 3. The image display method according to claim 2, wherein said magnetic field generating member is made to face at least one side of said reversible image display medium. 4. A method according to claim 1, wherein a relative movement direction between the surface of the magnetic field generating member and the reversible image display medium is one predetermined direction, and the magnetic field generating member is a magnetic pole in the predetermined one direction. The image display method according to claim 2, wherein a magnetic field generating member in which is arranged is used. 5. The at least one magnetic field generating member, wherein the relative movement direction between the surface of the magnetic field generating member and the reversible image display medium is a predetermined direction and a direction crossing the predetermined direction. 4. The image display method according to claim 2, wherein a magnetic field generating member having magnetic poles arranged in a transverse direction is used. 6. The magnetic field generating member according to claim 1, wherein a relative movement direction between the surface of the magnetic field generating member and the reversible image display medium is a predetermined direction. 4. The image display method according to claim 2, wherein a magnetic field generating member having magnetic poles arranged in a direction forming a predetermined angle is used. 7. The magnetic field generating member according to claim 1, wherein the relative movement direction between the surface of the magnetic field generating member and the reversible image display medium is a predetermined direction, and the magnetic field generating member crosses the predetermined one direction. 4. The image display method according to claim 2, wherein at least two magnetic poles are arranged in the direction, and a magnetic field generating member is used in which adjacent magnetic pole rows have N-pole positions and S-pole positions shifted from each other in the direction of the magnetic pole rows. 8. The magnetic field generating member according to claim 2, wherein said magnetic field generating members face both surfaces of said reversible image display medium, and magnetic field generating members having different magnetic pole arrangements are used as magnetic field generating members facing both surfaces of said medium. The image display method described in 1. 9. A method according to claim 1, wherein: two substrates facing each other with a predetermined gap; one or more developer storage cells formed between the two substrates and surrounded by a partition wall; A dry developer encapsulated in a cell, wherein the dry developer has at least two types of dry developing particles having different charging polarities and different optical reflection densities, and having triboelectric charging properties. A reversible image display medium, wherein at least one of the at least two types of developing particles is a magnetic developing particle, and the reversible image display medium is formed in an electrostatic field corresponding to an image to be formed. An image forming apparatus that displays an image by driving frictionally charged developing particles having opposite polarities within the image forming apparatus, and displays an image on the reversible image display medium before and / or before displaying the image on the reversible image display medium. To display An image forming apparatus comprising: at least one magnetic stirring force applying device for applying a magnetic field to a developer in the reversible image display medium from the outside to apply a stirring force to the developer. 10. The magnetic stirring device for applying a magnetic force includes a magnetic field generating member facing the reversible image display medium, and a relative movement between the surface of the reversible image display medium and the surface of the magnetic field generating member causes the developer to be applied to the developer. The image forming apparatus according to claim 9, wherein the intensity of the applied magnetic field is vibrated. 11. An image forming apparatus according to claim 10, wherein said magnetic stirring device includes said magnetic field generating member facing at least one surface of said reversible image display medium. 12. The apparatus according to claim 1, wherein at least one magnetic field generating member of the at least one magnetic stirrer applies a relative moving direction between the surface of the magnetic field generating member and the reversible image display medium in one predetermined direction. The generating member has magnetic poles arranged in the predetermined one direction.
2. The image forming apparatus according to 1. 13. The at least one magnetic field generating member in at least one magnetic stirrer, wherein the relative movement direction between the surface of the magnetic field generating member and the reversible image display medium is in one predetermined direction and crosses the direction. The image forming apparatus according to claim 10, wherein the magnetic field generating member has magnetic poles arranged in the transverse direction. 14. The apparatus according to claim 1, wherein at least one magnetic field generating member has at least one magnetic field generating member, wherein the relative movement direction between the surface of the magnetic field generating member and the reversible image display medium is a predetermined direction. 12. The image forming apparatus according to claim 10, wherein the generating member has magnetic poles arranged in a direction forming a predetermined angle with respect to the predetermined direction. 15. The method according to claim 15, wherein at least one magnetic field generating member of the at least one magnetic stirrer applies a relative moving direction between a surface of the magnetic field generating member and the reversible image display medium in a predetermined direction. 11. The generating member has at least two magnetic pole rows in a direction crossing the predetermined direction, and in adjacent magnetic pole rows, the N pole position and the S pole position are shifted from each other in the magnetic pole row direction. Or the image forming apparatus according to 11. 16. At least one magnetic stirrer has a magnetic field generating member facing both sides of the reversible image display medium, and the magnetic field generating members facing both sides of the medium have different magnetic pole arrangements. The image forming apparatus according to claim 10, wherein: