JP3135065B2 - Display method and display device using magnetophoresis - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a display method and a display device using magnetophoresis.

[Prior Art] A typical display method uses an electronic blackboard, which moves a writing instrument such as a board marker in a X or Y direction on a panel such as a whiteboard while responding to input information. To record and display predetermined characters and figures. However, this display method has problems such as the use of consumables such as writing instruments, and the removal of dry powder of the board marker when erased. Therefore, it is possible to easily display and erase on a relatively large screen without using writing instruments. A display method using magnetism has attracted attention. As a display method using such magnetism, for example, the following method has been proposed.

A display cell is formed between the magnetic recording sheet and the transparent sheet, a dispersion liquid in which magnetic particles are dispersed is sealed in the cell, and a magnetic latent image is formed on the magnetic recording sheet using a magnetic head.
A method in which magnetic particles are attracted by magnetophoresis using the magnetic latent image to produce a contrast between a non-magnetized portion and a display (Japanese Patent Publication No. 56-852).

A display cell is formed between the magnetic recording sheet and the transparent sheet, a dispersion liquid in which foil-like reflective magnetic particles are dispersed is sealed in the cell, and a magnetic head is used to form a magnetic latent image on the magnetic recording sheet. A method in which reflective magnetic particles are oriented by this magnetic latent image to form a contrast as in the case of liquid crystal and display is performed (Japanese Patent Laid-Open No. 61-233425).

A display panel is formed between at least two sheets having a transparent display surface, and a magnetic panel is used in which a dispersion liquid in which black magnetic particles are dispersed in a white medium is sealed. Magnetic particles are gathered on the opposite side (back side) of the surface, the display surface is kept in a state where the magnetic particles are concealed by the white dispersion medium, and then the display surface is applied with a magnetic field from a display surface using a magnetic pen made of magnet. A method in which the magnetic particles gathered on the side are subjected to magnetophoresis on the surface to perform display with a contrast between the white dispersion medium and the black magnetic particles (JP-A-59-21)
No. 4700).

[Problems to be solved by the invention]

However, the conventional display method using magnetism has the following problems.

Since the above-mentioned display methods use a magnetic recording sheet and a magnetic head, it is difficult to enlarge the screen, and the application is limited to a small one such as a card. In addition, since the magnetic particles used in the display methods (1) and (2) have a large specific gravity, sedimentation and separation are likely to occur, and the display becomes unstable. Also, since the magnetic particles take on a brownish or black color, they are limited to white / black display.

The above display method uses a magnetic pen composed of a simple magnet without using a magnetic recording sheet or a magnetic head, and here, a display panel has a side and a depth of about 2 mm on the entire surface of a transparent plastic. A honeycomb-shaped cell is formed and a dispersion of a white pigment and magnetic particles is sealed in the cell. First, the entire magnetic particles are sucked and moved to the back side by a uniform magnetic field for erasing from the back side, and the front side is used. Is formed by concealing with a white pigment and then applying a display or recording magnetic field from the display surface side with a magnetic pen made of magnets to migrate the magnetic particles from the back side and display. Screening is also possible.

However, this also has the following disadvantages.

(I) Since normal magnetic particles have a large specific gravity, if the display panel is kept vertical, sedimentation and separation will occur at the bottom of the honeycomb cell.

(Ii) Since the magnetic particles have a black or black-brown color, the display is limited to black / white display.

(Iii) Since the total amount of magnetic particles sealed in the honeycomb-shaped cell is sucked and moved by the magnetic field from the back surface to the front surface in a nodular form, the minimum unit of display is determined by the size of the cell,
No higher resolution can be obtained.

The present invention has solved the drawbacks of the prior art, has enabled a large-screen display, has no display instability due to sedimentation as described above, and has enabled color display. It is an object to provide a display method and a display device using magnetism.

[Means for solving the problem]

In order to achieve the above object, according to the present invention, a dispersion liquid of microcapsules in which a display cell is formed between two sheet-like supports having at least a transparent display surface, and a magnetic fluid is encapsulated in the cell. Is provided, and the display is performed with a contrast between the microcapsules and the dispersion liquid by applying a magnetic field to cause the microcapsules to perform magnetophoresis.

According to the present invention, at least the display surface is transparent.
After the microcapsules enclosing the magnetic fluid encapsulated in the display cell formed between the two sheet-like supports are sucked and moved to the back side by the erasing magnet arranged on the back side, the recording magnet is moved from the front side. A display method is provided, in which a display is performed by causing an image to be suction-moved by acting.

Further, according to the present invention, a recording means for applying a recording magnetic field and a dispersion of microcapsules containing a magnetic liquid in a display cell formed between at least two sheet-like supports having a transparent display surface. A display device is provided, comprising: a display panel filled with a liquid; and erasing means for applying an erasing magnetic field to the display panel from the back surface.

Further, according to the present invention, there is provided a display method or a display device in which the inclusion of the microcapsule enclosed in the cell is a colored magnetic fluid.

 Hereinafter, the present invention will be described in detail.

The present invention is a display method and a display device suitable for a relatively large screen such as an electronic blackboard, and is achieved by using a microencapsulated magnetic fluid instead of conventional magnetic particles for a magnetic material sealed in a display cell. Is what is done.

This magnetic fluid includes magnetite, manganese ferrite, nickel ferrite, cobalt ferrite, barium ferrite, nickel zinc ferrite of 200 mm or less,
Oil-based colloid in which the surface of ferromagnetic fine particles such as manganese zinc ferrite and magnesium zinc ferrite is coated with a long-chain unsaturated fatty acid such as oleic acid or linoleic acid, hydrophobized and dispersed in aliphatic hydrocarbon, aromatic hydrocarbon, etc. There is an aqueous-based colloidal solution in which a solution is hydrophobized as described above and further hydrophilized with an anionic or nonionic surfactant and dispersed in water. Unlike ordinary suspensions, these colloidal solutions have excellent dispersibility without solid-liquid separation such as sedimentation or aggregation due to gravity or a magnetic field, and the liquid itself exhibits a homogeneous and strong magnetic behavior. Has features.

The present invention uses a microcapsule containing the above magnetic fluid instead of the magnetic particles used in the conventional magnetic panel as described above. Specifically, at least two sheets having a transparent display surface are used. A display cell is formed between the support members, and a dispersion liquid in which microcapsules containing a magnetic fluid are dispersed in a white dispersion medium is sealed in the cell to form a magnetic display panel.

In the display method using this magnetic display panel, first, a uniform magnetic field is applied from the back side by an erasing magnet to attract and collect the entire microcapsule containing the magnetic fluid on the back side, and the display side is concealed by a white dispersion medium. Then, a display magnetic field is applied from the front side with a magnetic pen made of magnet, and the microcapsules gathered on the back side are magnetophoresed on the front side to display with a contrast between the white dispersion medium and the microcapsules. Is what you do.

A specific example of the dispersion liquid sealed in the display cell will be described.

(A) First, a microcapsule showing a magnetophoresis is a magnetic fluid emulsified and dispersed in an aqueous resin solution for a capsule coating by a simple or complex coacervation method from an aqueous gelatin / gum arabic solution when the magnetic fluid is oil-based. A well-known microencapsulation method such as a method of forming a resin film around droplets, or in the case of an aqueous base, a phase separation method from an organic solution of a resin for a capsule film or an interfacial polymerization method applicable to both oily and aqueous solutions. Created. In addition, as the colored magnetic fluid encapsulated in the microcapsules, in the case of a warm color system such as yellow or red, the magnetic substance itself is formed of a magnesium zinc ferrite exhibiting reddish brown and a yellow / red dye solution; In the case of a cool color such as blue, a solution formed of manganese zinc ferrite and a black / blue dye solution (in the case of black, no dye may be used) can be suitably used.

(B) In addition, as a white dispersion medium for forming a background of a display panel by subjecting the microcapsules to magnetophoresis, a white pigment such as zinc oxide or titanium oxide is dispersed in the presence of a dispersant in an aqueous system or a ball mill or the like. Those finely dispersed in oil-based solvents such as aliphatic hydrocarbons and aromatic hydrocarbons are used.

(C) The dispersion to be sealed in the display cell is as described in (a) above.
Can be obtained by mixing the microcapsules obtained in step (b) with the white dispersion medium obtained in step (b). When the microcapsule inclusions in step (a) are oily, the dispersion in step (b) is a water-based capsule slurry. When the inclusions in (a) are aqueous, and when the dispersion in (b) is combined with an oil-based dispersion, the capsule slurry liquid and the white dispersion medium are easily stirred and mixed. It can be manufactured only by doing. Of course, when the capsule slurry liquid obtained in (a) is dried by spray drying or the like and taken out as capsule powder, as (b), any of water-based and oil-based can be dispersed and used. In consideration of the permeability of the capsule film, it is preferable to disperse the oil-based magnetic fluid-containing capsule in an aqueous white dispersion medium, and conversely, to disperse the aqueous magnetic fluid-containing capsule in an oil-based white dispersion medium, because of excellent stability.

The display dispersion liquid in which the microcapsules containing the magnetic fluid thus obtained are dispersed is used by being enclosed in a display cell.

〔Example〕

FIG. 1 is a sectional view showing a configuration of a display device according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a magnetic display panel, and a display cell (for example, a honeycomb) is provided between a support 11 and a sheet-like (including a plate-like) support 11 and 12 having a transparent display side via an appropriate spacer 13.
The cell 14 is formed, and a liquid in which microcapsules 142 containing a magnetic fluid are dispersed in a white dispersion medium 141 is sealed in the cell 14.

This microcapsule 142 is, as shown in FIG.
A magnetic fluid 144 in which ultrafine magnetic powder 143 having a particle size of 200 ° or less is dispersed in a colloidal state as an inclusion is coated on a capsule film 145.

The display method using the magnetic display panel 1 is as follows. First, the erasing magnet 2 is moved in the direction of arrow A from the back side and an erasing magnetic field is applied, so that the whole of the microcapsules 142 in the display cell 14 is exposed on the back side. Suction and assemble, then pen tip 3
By moving the magnetic pen 3 holding the magnet 32 from 1 on the display surface according to character / graphic information, for example, as indicated by an arrow B, the microcapsules 142 gathered on the back side are magnetized on the front side to be colored. An arbitrary color display is performed by the contrast exhibited by the microcapsules 142 containing the ionic magnetic fluid and the white dispersion medium 141.

FIG. 3 is a cross-sectional view of a conventional display device shown for comparison, in which a display cell 14 is formed via a spacer 13 between sheet-like supports 11 and 12 having a transparent display side.
The liquid 1400 in which the magnetic particles 1420 are dispersed in a white dispersion medium 1410 is enclosed in 14 to constitute the magnetic display panel 1. Here, as the magnetic particles 1420, brown or black particles are used.

The display method using the magnetic display panel 1 is as follows. First, the erasing magnet 2 is moved from the back surface of the magnetic display panel 1 as shown by the arrow A, and the magnetic pen 3 holding the display magnet 32 over the entire magnetic particles is first moved by the arrow B. By moving the magnetic particles as described above, the magnetic particles at that portion are subjected to magnetophoresis on the surface side to display only one color.

〔The invention's effect〕

According to the present invention, by using a magnetic display panel, consumables such as markers are not required, and at the same time, erasure powder damage can be eliminated. By using a magnetic fluid having a lower specific gravity than the normal magnetic particles as the magnetic particles to be subjected to the magnetophoresis, problems such as sedimentation and separation can be solved, and stable and fast response display can be achieved.

In addition, the microcapsules enclosing the magnetophoretic particles with a magnetic fluid do not agglomerate and behave by the magnetic field unlike ordinary magnetic particles. Regardless, high-resolution display can always be achieved.

Furthermore, by encapsulating and using a colored magnetic fluid, it is possible to display an image in which normal display is limited to black / white as an arbitrary color display.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the structure of a display device according to an embodiment of the present invention, FIG. 2 is a sectional view showing the structure of a microcapsule,
FIG. 3 is a sectional view showing the structure of a conventional display device. DESCRIPTION OF SYMBOLS 1 ... Magnetic display panel 2 ... Magnet for erasing 3 ... Magnetic pen 11, 12 ... Sheet support 13 ... Spacer 14 ... Display cell 141 ... White dispersion medium 142 ... Microcapsule 143 ... Ultra Fine magnetic powder 144: Magnetic fluid 145: Capsule coating

Continuation of front page (58) Fields investigated (Int.Cl. ⁷ , DB name) G09F 9/30-9/46 G02F 1/167 G02F 1/19 B43L 1/00 G11B 5/62-5/82

Claims (5)

(57) [Claims] 1. A display cell is formed between at least two sheet-like supports having a transparent display surface, a dispersion of microcapsules containing a magnetic fluid is sealed in the cells, and a microcapsule is applied by applying a magnetic field. A display method, wherein a display is performed by contrasting a microcapsule with a dispersion liquid by magnetizing the capsule. 2. A microcapsule enclosing a magnetic fluid encapsulated in a display cell formed between at least two sheet-like supports having a transparent display surface at least on the back side by an erasing magnet arranged on the back side. A display method characterized in that, after the suction movement, a display is performed by causing the recording magnet to act from the front side to perform image-wise suction movement. 3. The display method according to claim 1, wherein the inclusion of the microcapsules enclosed in the cell is a colored magnetic fluid. 4. A recording means for applying a recording magnetic field, and a dispersion liquid of microcapsules enclosing a magnetic fluid in a display cell formed between two sheet-like supports having at least a transparent display surface. A display device comprising: a display panel comprising: a display panel; and an erasing means for applying an erasing magnetic field to the display panel from a back surface. 5. The display device according to claim 4, wherein the inclusion of the microcapsules sealed in the cell is a colored magnetic fluid.