JPH04175196A - Color display method and apparatus utilizing magnetic migration and magnetic pen used therein - Google Patents

Abstract

PURPOSE:To perform display rich in data quantity by a method wherein two or more kinds of magnetic particles different in magnetic characteristics and hue are contained in the cells of a magnetic display panel and a magnetic pen variable in acting magnetic field intensity is used to the magnetic particles to selectively subject the particles to magnetic migration. CONSTITUTION:A dispersion 140' of two or more kinds of colored magnetic particles 142, 143 different in hue and magnetic characteristic (saturation magnetization) is sealed in display cells 140 to form a color magnetic display panel 10. Magnetic pens 30, 40 each generating a magnetic field having intensity sufficient to selectively subject the colored magnetic particles 142,143 in the display cells 140 to magnetic migration are used to apply an erasing magnetic fields to the rear of the magnetic display panel 10. By this method, display rich in data quantity can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color display method using magnetophoresis, a color display device, and a magnetic pen used therefor.

[Conventional technology]

A typical display method uses an electronic blackboard, in which a writing instrument such as a board marker is moved in the x and y directions on a panel such as a white board, and predetermined characters and characters are displayed according to input information. It is used to record and display figures, etc. However, this display method has problems such as the use of consumables such as a writing instrument and the dry powder of the board marker when erased, so it is possible to easily display and erase on a relatively large screen without using a writing instrument. Display methods using magnetism are attracting attention. As display methods using such magnetism, the following methods have been proposed, for example.

■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 of attracting magnetic particles by magnetophoresis using this magnetic latent image and creating a contrast between the non-magnetized portion and displaying the image (Japanese Patent Publication No. 56-852).

■A display cell is formed between the magnetic recording sheet and the transparent sheet, a dispersion liquid containing foil-shaped reflective magnetic particles is filled in the cell, and a magnetic latent image is formed on the magnetic recording sheet using a magnetic head. A method of displaying by forming a magnetic latent image, orienting reflective magnetic particles using this magnetic latent image, and producing contrast as in the case of liquid crystal (Japanese Unexamined Patent Publication No. 61-233425).

■A display cell is formed between two sheets with at least a transparent display surface, and a magnetic panel is filled with a dispersion liquid of black magnetic particles dispersed in a white medium. Magnetic particles are gathered on the opposite side (back side) from the display surface, and the display surface is rippled with a white dispersion medium.
Then, by applying a display magnetic field from the display surface side with a magnetic pen made of a magnet, the magnetic particles gathered on the back surface are magnetophoretically moved to the surface, and the white dispersion medium and the black magnetic particles are separated. Method of displaying with contrast (Japanese Unexamined Patent Publication No. 59
-214700, etc.).

[Problem to be solved by the invention]

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

Since the above display methods (1) and (2) use a magnetic recording sheet and a magnetic head, it is difficult to increase the screen size, and the application is limited to small items such as cards. Furthermore, since the magnetic particles exhibit a brown to black color, white/black display is limited.

The display method (■) above uses a magnetic panel and a magnetic pen instead of a magnetic recording sheet and magnetic head, so it is possible to enlarge the screen. It has the disadvantage that it is limited to white/black display because it exhibits a brownish to black color.

On the other hand, color display is desired in order to improve the quality and quantity of displayed information.

SUMMARY OF THE INVENTION An object of the present invention is to provide a display method and a display device that can overcome the drawbacks of the prior art and can display a large screen and also display in color.

[Means to solve the problem]

In order to achieve the above object, according to the present invention, a display cell is formed between two sheet-like supports having at least transparent display surfaces, and a display cell is formed with different magnetization characteristics and hue or tone. A dispersion of two or more types of magnetic particles is enclosed, and the magnetic particles are generated using two or more magnetic pens with different magnetic field strengths acting on the magnetic particles or one magnetic pen with variable working magnetic field strength. A color display method is provided, which is characterized in that color display is performed by selectively performing magnetophoresis.

Further, according to the present invention, a display cell is formed between two sheet-like supports having at least transparent display surfaces, and two or more types of display cells having different magnetization characteristics and hues or tones are formed in the cell. There is provided a color display device comprising a display panel sealed with a dispersion of magnetic particles and an erasing means for applying an erasing magnetic field to the display panel from the back surface.

Furthermore, according to the present invention, a magnetic pen for the color display device has a magnet that generates a magnetic field of a predetermined strength, and a mechanism that can change the position of the magnet in the axial direction within the magnetic pen. is provided.

The present invention will be explained in detail below.

The present invention relates to colorization and color display methods for magnetic display panels that can be applied to display devices with relatively large screens such as electronic whiteboards, and relates to a method for colorizing magnetic display panels and displaying colors in display cells of magnetic display panels. A color display is achieved by enclosing a dispersion of two or more types of magnetic particles having different magnetic properties, applying magnetic fields of different strengths to the magnetic display panel, and causing the magnetic particles to selectively migrate magnetophoresis.

The method for coloring the magnetic particles used in the present invention includes (1) a method in which the surface of the magnetic particles is coated with a white opaque pigment and then colored with a desired dye, pigment, etc. Publication No. 59-197047, No. 60-6952
(i) Magnetic fine particles are dispersed in a binder solution, granulated by a spray-try method, etc., and then the surface is coated with titanium white (titanium oxide white pigment). A method of coating and further dyeing or coloring it with a pigment (e.g. European Patent Publication No. 75,346); (iii) coating ultra-fine (approximately 200 Å or less) magnetic particles exhibiting optical transparency with a dye or pigment, etc. Direct coloring method (U.S. Pat.
Various methods are possible, such as a method in which spherical or elliptic spherical iron powder of ~12 μm is dispersed together with a dye and pigment in a binder resin, and then pulverized (US Pat. No. 4,803.143, etc.).

In addition, in the above, the magnetic particles include iron, nickel,
Particles such as cobalt, magnetite, manganese ferrite, nickel ferrite, barium ferrite, nickel ferrite, copper lead ferrite, macan zinc ferrite, magnesium zinc ferrite, etc. are used. Do t. In other words, these particles are colored to a desired color tone (leaving as is if they are black), and colored magnetic particles with different magnetization characteristics can be created by changing the composition ratio of magnetic particles and binder or dye and pigment as shown below. Obtainable.

Next, a method for producing colored magnetic particles with different magnetization properties will be described.

(a) Iron pentacarbonyl (U.S. Patent Box 4,803.1)
Iron powder having a saturation magnetization of 153 emu/g and having a particle size of 2 to 7 μm [11 (average particle size: 4 pm)] obtained by spray-drying iron powder (see No. 43) at a wall temperature of 250° C. was prepared. Next, 0.3 g of antioxidant and 30 g of ethylene-vinyl acetate copolymer resin
12 g of titanium oxide, 18 g of copper phthalocyanine and 90 g of the above iron powder are dissolved in 500 g of methylene chloride.
By spray-drying this dispersion at an ambient temperature of 50°C, the particles have a particle size of 10 to 15 μm and a saturation magnetization of 5.
Blue magnetic particles of 2 emu/g were obtained.

(b) Same as above (a) except that titanium oxide was replaced with zinc oxide and copper phthalocyanine was replaced with red disperse dye.
g of red magnetic particles were obtained.

(c) Green magnetism with a particle size of lO to 16 Plffl and a saturation magnetization of 50 emu/g in the same manner as in (a) above except that 6 g of zinc oxide and 6 g of stearic acid were used for titanium oxide and 20 g of phthalocyanine green was used for copper phthalocyanine. Particles were obtained.

(d) In the above (a), the antioxidant, titanium oxide and copper phthalocyanine are removed, and iron powder is further replaced with an average particle size of 0.
．． 10g of ferrite powder with saturated magnetization of 81emu# in 2μ river
Black magnetic particles with a particle size of 10-12 μm and a saturation magnetization of 20 emu/g were obtained in exactly the same manner except that .

In addition, in the above, the saturation magnetization of each magnetic particle is a magnetic field of 160
This is a measurement value of KA/m using a magnetic balance.

In the present invention, a color magnetic display panel is formed by sealing the dispersion of two or more colored magnetic particles having different hues or tones and magnetization characteristics (saturation magnetization) in a display cell. , a magnetic pen that generates a magnetic field strong enough to selectively cause the colored magnetic particles in the display cell to undergo magnetophoresis (a single pen may be used as long as it applies magnetic fields of different strengths to the magnetic particles, A large-area color display can be realized by using a combination of two or more of them) and an erasing means that applies an erasing magnetic field from the back side of the magnetic display panel.

〔Example〕

FIG. 1 is a sectional view showing the configuration of a color display device according to an embodiment of the present invention. In the figure, 1o is a color magnetic display panel, and the display side is a transparent sheet-like (including plate-like) support + 1
0 and! A display cell +40 is formed between 20 and 20 with a suitable spacer 130 interposed therebetween, and in this cell 140, the red magnetic particles 142 obtained in (b) above and the above are placed in a white dispersion medium 141 in which titanium oxide or the like is dispersed. It is constructed by enclosing a liquid 140' in which approximately equal amounts of the black magnetic particles 143 obtained in (d) are dispersed.

In the color display method using this color magnetic display panel 10, the moon magnet 2 is first erased from the back surface of the color magnetic display panel 1o.
0 (approximately 80 θ Gauss) in the direction of the arrow to apply an erasing magnetic field and collect all the magnetic particles in the cell 140 on the back side. Next, when the magnetic pen 30, which has a relatively weak magnet 320 with a magnetic force of about 400 Gauss held at the tip of the pen 310, is moved by an arrow B with respect to the display surface of the color magnetic display panel 10, the saturation magnetization becomes 50 emu/g.
Only the red magnetic particles 142 selectively move to the surface side by magnetophoresis, and a red display is performed in that part.

In addition, the magnet 420 has a strong magnetic field J of about 1000 Gauss.
When the magnetic pen 40 held at the tip of the pen 410 is moved by arrow C, there are red magnetic particles 142 and black magnetic particles! Since both particles of No. 43 simultaneously magnetophorese and move toward the surface side, they appear black on the panel surface side, and a black display is performed. As described above, according to the device shown in FIG. 1, it is possible to display two colors of red/black: red when using the magnetic pen 30 with a small magnetic force, and black when using the magnetic pen 40 with a large magnetic force.

In the above example, a two-color display of red/black was possible, but if the blue magnetic particles obtained in (a) above were used in place of the red magnetic particles +42 in exactly the same way, a two-color display of blue/black could be achieved. Furthermore, if the green magnetic particles obtained in step (c) above are used in place of the second red magnetic particle, two-color display of green/black becomes possible. Furthermore, by appropriately selecting dyes and pigments, it is possible to display multiple colors of desired hues or tones other than those mentioned above.

Next, the embodiment shown in FIG. 2 has a magnetic pen 30 having a relatively weak magnet 320 and a strong magnet 4.
20 magnetic pens 40 are used respectively, whereas one magnetic pen 50 is used to perform the same operations as those described above. This magnetic pen 50
has a strong magnet 50 inside, and by moving the strong magnet 520 up and down to change the distance from the color display panel 10, it can be placed in the same state as the magnetic pens 30 and 40 in FIG.
30', 40').

In the color display method using this, first, by moving the erasing magnet 20 from the back side of the display panel 0 in the direction of arrow A, all the magnetic particles in the cell +40 are gathered on the back side. Next, from the display surface side, about 1,000 screws integrated with the shaft rod 540 are placed in the holder 530 having the cover 510 at the tip.
The strong Gauss magnet 520 is normally pushed upward by the spring 550 (state 30'), and when the notch 590 is pressed, the notch hole 56 of the holder 530 is pressed.
The hook 570 is attached to the 0, and the magnet 520 is attached to the leading edge)
Then, when the release button 580 is pressed, the cover 510 and the magnet 520 can form a gap as shown in (30'') using the magnetic pen 50. When the notch 590 is pressed (40'), characters can be drawn. , according to the graphic information. Then, a strong magnetic field acts directly and both the red magnetic particles 142 and the black magnetic particles 143 undergo magnetophoresis at the same time, resulting in a black display. In addition, when the gear is held at the tip of the magnet (30') and moved by arrow C according to the text and graphic information, the magnetic field acting on the magnetic particles is weak, so the saturation magnetization is 50e.
[mu/g and large red magnetic particles] Only 42 selectively undergoes magnetophoresis and is displayed in red. In this way, one magnetic pen 50 with movable magnet 520 can display two colors of red and black.

However, the magnet movable/cent mechanism here is only one example, and is not limited to this. For example, one magnetic pen has an electromagnet built into it, and by changing the applied voltage at any time via a changeover switch, the electromagnet can be used as both a strong magnet and a relatively weak magnet. It may be.

FIG. 3 is a sectional view of a conventional display device shown for comparison, in which a display cell 14 is formed between sheet-like supports 11 and 12 whose display side is transparent with a spacer 13 interposed therebetween. Inside, magnetic particles 14 are contained in a white dispersion medium 141.
A magnetic display panel 1 is constructed by enclosing a liquid 140 in which 2 is dispersed. Here, the magnetic particles 142 used are brown to black.

In the display method using this magnetic display panel 1, the erasing magnet 2 is moved from the back side of the magnetic display panel l in the direction of arrow A' to collect all the magnetic particles on the back side, and then the pen 3
By moving the magnetic pen 3, which holds a display magnet 32 at the tip of the pen 1, in the direction of arrow B', the magnetic particles in that area are magnetophoretically moved to the surface side, thereby displaying only one color. In this conventional device, instead of brown or black magnetic particles as magnetic particles +42, (a), (b
), (c), and (d), color display is possible by using colored magnetic particles, but even in that case, the display is limited to one color, and multicolor display as in the present invention is not possible. It cannot be done.

〔Effect of the invention〕

According to the present invention, the following effects can be obtained.

■ Two or more types of magnetic particles with different magnetic properties and hues or tones are included in the cells of the magnetic display panel, and each magnetic particle is selectively selected using a magnetic pen with variable magnetic field strength. By causing magnetophoresis to occur, two or more colors can be displayed, making it possible to display a rich amount of information.

■ Display using magnetophoresis eliminates the problem of consumption of writing instruments such as display markers and the generation of dry marker powder when erasing.

■When displaying colors using a magnetic display panel whose display color is limited to one color, is it necessary to use markers of different colors to write on the magnetic display panel?According to the present invention,
It is possible to display colors with just one magnetic display panel, and there is no need to use consumables such as markers.

■Furthermore, if the magnetic field strength can be varied with one magnetic pen, one magnetic pen can be used for two colors with a single touch, making it more economical and easier to operate than a pen with separate magnetic pens. It is also excellent in sex.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of a display device and a magnetic pen according to an embodiment of the present invention, FIG. 2 is a sectional view showing the structure of a display device and a magnetic pen according to another embodiment of the present invention, and FIG. FIG. 3 is a sectional view showing the configuration of a conventional display device and magnetic pen. 10・Color magnetic display panel 20・・Erasing magnet 3θ, 40.50 Magnetic pen 110, 120 Sheet-like support 130・Spacer 140・・Display cell +41・White dispersion medium 142, 143・Colored magnetic particles 320, 420 .520 Magnet patent applicant Rico Co., Ltd. -

Claims (3)

[Claims] (1) A display cell is formed between two sheet-like supports with at least transparent display surfaces, and a dispersion of two or more types of magnetic particles having different magnetization characteristics and hues or tones is disposed within the cell. By enclosing the magnetic particles and scanning the magnetic particles with two or more magnetic pens each having a different magnetic field strength or one magnetic pen with a variable working magnetic field strength, the magnetic particles can be selectively magnetophoretically migrated. A color display method characterized by displaying. (2) A display cell is formed between two sheet-like supports with at least transparent display surfaces, and a dispersion of two or more types of magnetic particles having different magnetization characteristics and hues or tones is disposed within the cell. What is claimed is: 1. A color display device comprising: a display panel in which a color display panel is enclosed; and erasing means for applying an erasing magnetic field to the display panel from the back side. (3) A magnetic pen for a color display device according to claim 2, comprising a magnet that generates a magnetic field of a predetermined strength, and a mechanism that can vary the position of the magnet in the axial direction within the magnetic pen.