JPS5931710B2 - Display device set using magnetic force - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a display device set that utilizes magnetic force, which is a combination of a magnetic panel that can clearly display and erase records using magnetism, and magnetic means that applies a magnetic field to the magnetic panel. be.

Conventionally, such a display device set includes a magnetic panel that changes the color of a dispersion system in which magnetic fine powder is dispersed in a colored liquid dispersion medium by applying a magnetic field to the dispersion system; A magnetic pen that applies the magnetic field is known.

This display device set is made by applying the magnetic field of a magnetic pen to a dispersion system in which fine magnetic powder of a different color from the dispersion medium is dispersed in a dispersion medium colored with a dye or pigment to cause the magnetic fine powder to migrate. This method changes the color of the dispersion system by changing the extent to which the magnetic fine powder in the electrophoresis area is shaded by the dispersion medium, but it has the following major drawbacks.

In other words, when a dispersed system is sealed between two substrates facing each other and a magnetic force is applied by drawing letters or patterns on one of the substrates with a magnetic pen, the magnetic fine powder in the dispersed system is attracted to the magnetic poles. However, the specific gravity of the magnetic fine powder is much higher than the specific gravity of the dispersion medium, so the attracted magnetic fine powder gradually settles over time, so the characters and patterns cannot be retained for a long time. There is.

In addition, all the magnetic fine powder that has been subjected to the magnetic force by the magnetic pen is attracted to the magnetic pen, so even the magnetic fine powder that was far away from the magnetic pen is attracted, resulting in poor sharpness. There were also drawbacks in which only very blurred characters and patterns could be obtained.

In order to prevent the magnetic fine powder from settling, for example, the magnetic fine powder may be made into extremely fine particles, or the magnetic fine powder may be coated with a large amount of low specific gravity resin, etc., so that the apparent specific gravity of the magnetic fine powder is lowered near the dispersion medium. If the magnetic powder is lowered to a lower temperature, the magnetic force acting on the magnetic fine powder will of course be extremely reduced, making it difficult to be attracted to the magnetic pole of the magnetic pen, resulting in the fatal defect that it will not be possible to obtain dark and clear characters and patterns. arise.

Also, when erasing characters and patterns drawn by applying magnetic force from the opposite side of the substrate, the fine magnetic powder is difficult to be attracted to the magnetic poles on the opposite side, so it is difficult to erase them neatly. As such recording and erasing is repeated, the magnetic fine powder becomes suspended in the dispersion system and darkens, making it difficult to record, display, and erase characters and patterns. Until now, a practical magnetic panel has not been available.

The present invention provides an excellent display device set using magnetic force that completely solves the above-mentioned drawbacks, and is composed of (auto)magnetic fine particles, a dispersion medium, a fine particle thickener, and optionally a coloring agent. It is a combination of a magnetic panel in which a plastic dispersion liquid having a yield value of 5 (!Yn?/Cd or more) is sealed between two substrates, and (B) a magnetic means for applying a magnetic field to magnetic fine particles in the plastic dispersion liquid. This is a display device set that uses magnetic force.

Magnetic panels that use a dispersion system in which magnetic fine powder is dispersed in a colored liquid dispersion medium have the fatal flaws mentioned above. Adding particulate thickener to the liquid 5
By creating a plastic dispersion liquid with a yield value of dyne/C77f or higher and using it to create a magnetic panel, it is possible to display clear, high-contrast characters and patterns without any blurring, and the display remains stable for a long time. They have discovered that a magnetic panel can be obtained that can be held and erased cleanly without leaving any stains.

That is, the greatest feature of the present invention is the use of a magnetic fine particle dispersion liquid that has a yield value of 5 dyn1 cd or more by using a fine particle thickener.

The present inventor has discovered that in a dispersion liquid in which magnetic fine particles are dispersed, in order to stably hold the magnetic fine particles with a large specific gravity in a specific position in the dispersion liquid, and to move the magnetic fine particles all at once when they receive a magnetic force of a certain level or more, However, good results cannot be obtained simply by adjusting the viscosity of the dispersion, using dispersion stabilizers or protective colloids, or making the specific gravity of the dispersion medium and magnetic particles the same.Such good performance depends on the dispersion. They discovered that this can be achieved only within a certain range of yield values, and further research revealed that good results can be obtained in dispersions adjusted to a yield value of 5 dyne7/Cd or higher using a fine particle thickener.

When this yield value is smaller than 5 dyn9/Cd, only a vague display is obtained, and the magnetic particles rapidly settle, resulting in misreading or not being able to be read, and the display completely disappears after a period of time. This tendency is most severe when using a dispersion liquid with a yield value of 0 dyr1e/Cd without the addition of a particulate thickener, and decreases when a yield value starts to appear after adding a particulate thickener, but when the yield value is 51 yne/Cd. C
A suitable magnetic panel without the above-mentioned drawbacks can only be obtained when the dispersion liquid is made into a liquid having a particle diameter of d or more.

Therefore, the yield value of the plastic dispersion liquid of the present invention is 5<1ν
It must be 7d or higher. [Yield value] used in the present invention refers to the limit value (minimum value) of stress required to cause the liquid to flow (permanent deformation) by applying stress to the liquid. For example, if the vertical axis is In the liquid flow curve shown in FIG. 6, where the strain rate is D and the horizontal axis is the stress S:. It is expressed by the stress shown at point A.

The magnetic fine particles used in the present invention are black magnetite, γ-
Fine particles of oxide magnetic materials such as hematite, chromium dioxide, and ferrite, and alloy-based metal magnetic materials such as cobalt and nickel, and granulated products of these fine particles can be used. The size of the magnetic fine particles is preferably 10 microns or more in diameter. If the diameter is smaller than 10 microns, it becomes difficult for the magnetic force of the magnetic means to work during recording and erasing.
The electrophoretic properties of the magnetic particles deteriorate, and the magnetic particles become suspended in the dispersion medium, making the magnetic panel appear black and dirty. In addition, even if the diameter of the magnetic fine particles is smaller than 10 microns, the magnetic fine particles aggregate in the dispersion liquid and have an apparent diameter of 10 microns or more, yet a suitable result can be obtained. The magnetic particles are kneaded with a resin solution, dried and then pulverized, or sprayed and dried to bind the magnetic particles together and make the apparent size of the magnetic particles fall within a certain range. It is preferable to granulate the particles so that they are aligned in order to improve migration properties and display clarity. However, from the viewpoint of magnetic sensitivity, the solid content of the resin used for granulation must be 40% by weight or less based on the amount of magnetic fine particles, and preferably 30% by weight or less. The granulated magnetic fine particles produced in this manner are also referred to as magnetic fine particles in the present invention. The dispersion medium can be either a polar dispersion medium such as water or glycols, or a nonpolar dispersion medium such as an organic solvent or oil.

The fine particle thickener used to obtain the yield value is fine powder silicic acid consisting of anhydrous silicic acid, hydrated silicic acid, hydrated calcium silicate, hydrated aluminum silicate, silica powder, diatomaceous earth, organic bentonite, etc., singly or in mixtures. and fine silicates, alumina, ultrafine calcium carbonate, minor calcium carbonate, ultrafine activated calcium carbonate, ground calcium carbonate, hydrous basic magnesium carbonate, barium sulfate,
These fine particle thickeners can be used alone or in combination.

The amount used varies somewhat depending on the type of dispersion medium and thickener, but in general, adding 2% or more for polar dispersion media and 0.5% or more for non-polar dispersion media will give a yield value of 5 dyneCd or more. be able to. The coloring agent is used to impart hiding properties and color tone to the plastic dispersion liquid, and white pigments, other dyes, or pigments can be used. It is preferable to add 10% or less, preferably 3% or less of a coloring agent to the plastic dispersion liquid, because it can increase the contrast between the plastic dispersion liquid and the magnetic fine particles, and as a result, the display can be clearly read. If the amount of colorant is too large, the display made of the magnetic fine powder will become unclear, which is not good. Note that when the fine particle thickener itself has sufficient hiding properties and has a color tone that contrasts with the magnetic fine particles, there is no need to separately add a coloring agent. The distance between the two substrates of the magnetic panel that encloses the plastic dispersion liquid is 0.3 to 20 mm, preferably 0.5 to 2.0 mm.

Within this range, a clear display with high contrast can be obtained, and it can be erased cleanly. In this case, the amount of magnetic fine particles used in the plastic dispersion liquid is 20 parts per 100 parts of the dispersion medium.
must be at least 100%. Below this amount, when characters or patterns are recorded on one substrate using magnetic means, the amount of magnetic fine particles attracted to the substrate side by the magnetic pen is enough to tightly fill the trajectory drawn by the magnetic means without any gaps. As a result, the display becomes discontinuous and broken, resulting in a very inferior magnetic panel. Of the two substrates, it is desirable that the one on which the recorded display is read is transparent, but depending on the application, a translucent substrate can also be used, and various plastics and glasses can be used. The surface substrate does not necessarily need to be transparent, and various plastics, glass, metals, etc. can be used.

These plastics and glasses may be colored or uncolored. Furthermore, it is necessary to prevent the plastic dispersion liquid sealed between the two substrates from flowing out. For this purpose, for example, the periphery between the two substrates is fixed with a plate, sealed with adhesive, or fused. Also, after pasting the substrate on one side of the plate with individual independent cells penetrated,
A plastic dispersion liquid is sealed in each cell and then a substrate is attached to the other side to make a magnetic panel, or a plastic dispersion liquid is sealed in each cell of a plate that is not penetrated but has individual independent cells. After that, by pasting the substrate to make a magnetic panel, you will be able to get a clearer display with higher contrast than when you do not use a multi-cell board. It becomes very stable.
The shape of the cells in this case may be circular or polygonal, but the thinner the partition walls that separate each cell, the better the display with continuity can be obtained, preferably 0.5 m7! It is desirable that the thickness be less than or equal to L thickness. By arranging such cells, for example, in a 7 segment or dot matrix,
Alternatively, by arranging them in a desired character or graphic pattern, a magnetic panel having picture element parts can be made. Magnetic means include a magnetic pen made of a permanent magnet or an electromagnet, a magnetic head, a printing device with permanent magnet figures and letters on its surface, and a magnetic material with holes in the figures and letters and having a magnetic shielding effect. Examples include a combination of a sheet and a magnet that applies a magnetic field through the holes, and a dot matrix wire device having a magnet at the tip of the wire.

These display device sets can be used for children's toys, teaching materials, calligraphy, various games, notice board sets, or underwater record display sets that record without using liquid ink and utilize a record erasing system that is completely stable against water. It can be widely applied as

Next, the present invention will be explained with reference to the drawings. In the display device set shown in FIG. 1, a front substrate 1 and a back substrate 2 made of a transparent polyester film with a thickness of 0.1 mm are arranged at an interval of 1.3 mm, a plastic dispersion liquid 3 is placed between them, and the surroundings are A magnetic panel 5 is formed by enclosing a separator plate 4, and a magnetic pen 7 having a permanent magnet 6 at the tip is combined therewith. The surface of the back substrate 2 of the magnetic panel 5 thus constructed is scanned with an erasing magnet such as a permanent magnet or an electromagnet, and a magnetic field is applied to the plastic dispersion liquid 3 to attract magnetic fine particles to the back substrate 2 side. When the permanent magnet 6 is applied to the surface of the front substrate 1 and the magnetic pen 7 is moved, the magnetic fine particles in the plastic dispersion liquid 3 that were attracted to the back substrate 2 side are attracted by the magnetic pen 7 and moved to the front substrate 1 side. As it moves, a contrast is created in the plastic dispersion liquid 3 and a display is formed. By repeating the above operations, recording, displaying, and erasing on the magnetic panel 5 can be performed any number of times. Note that the permanent magnet 6 of the magnetic pen 7 includes a flexible magnet. This flexible magnet is molded into the shape of the tip of a brush, or rolled into a sheet into a cylinder shape, and when the tip is pressed against the surface of the front substrate 1, a magnetic pen is created that produces handwriting similar to that of a brush. be able to. The display device set shown in FIG. 2 is a combination of a magnetic panel 8 and a magnetic head 9. The magnetic panel 8 has a back substrate 10 and partition walls 11 that form independent cells. Different from 5.

The thus assembled magnetic panel 8 and magnetic head 9 are operated in the same manner as in the previous embodiment to form a display. Third
The display device set shown in the figure is a combination of a magnetic panel 12 and a printing tool 14 having figures and characters formed by a permanent magnet 13 on its surface.

The magnetic panel 12 has a 1.3 mm diameter that passes through independent 4 mm square cells between the front substrate 1 and the back substrate 2.
This differs from the magnetic panels 5 and 8 in that a thick multi-cell plate 15 is provided. After attracting magnetic fine particles to the back substrate 2 side of the magnetic panel 12 produced in this manner in the same manner as the magnetic panels 5 and 8, the permanent magnet 13 of the printing tool 14 is attached to the surface of the front substrate 1. When pressed, the magnetic fine particles in the plastic dispersion liquid 3 that had been attracted to the back substrate 2 side are attracted to the permanent magnet 13 and move to the front substrate 1 side, forming a display of figures and characters corresponding to the permanent magnet 13. . The display device set shown in FIG. 4 includes a magnetic panel 1, a magnetic sheet 17 having holes 16 in the shape of figures and letters, and having a magnetic shielding effect.
and a flat permanent magnet 18.

After attracting magnetic fine particles to the back substrate 2 side of the magnetic panel 1, the magnetic sheet 17 is placed on the surface of the front substrate 1, and then the permanent magnet 18 is pressed against the hole 16 of the magnetic sheet 17. The magnetic fine particles in the plastic dispersion liquid 3, which had been attracted to the 2 side, are attracted to the permanent magnet 18 and move to the front substrate 1 side, and a display corresponding to the hole 16 in the shape of a figure or a letter is formed. In this case, an electromagnet may be used instead of the permanent magnet 18. The display device set in FIG. 5 includes a magnetic panel 19 and a dot matrix wire device 20.
It is a combination of

The magnetic panel 19 has the peripheral edge of the back substrate 21 adhered to the front substrate 1, and the multi-cell plate 1 is placed between the front substrate 1 and the back substrate 21.
This magnetic panel differs from the magnetic panels 5, 8, and 12 in that 5 is provided. The dot matrix wire device 20 has a permanent magnet 2 at the tip.
2, a head 24 which has permanent magnets 22 arranged in a dot matrix and holds the wires 23 so as to be freely retractable, and a control section 25 which individually controls the retraction and retraction of the wires 23. After scanning the surface substrate 1 of the magnetic panel 19 thus produced with an erasing magnet such as a permanent magnet or an electromagnet to apply a magnetic field to the plastic dispersion liquid 3 and attracting the magnetic fine particles to the surface substrate 1 side, When the wire 23 of the dot matrix wire device 20 is projected in a desired character or figure shape and the magnet 22 of the wire 23 is pressed against the back substrate 21, the magnetic fine particles in the plastic dispersion liquid 3 that have been attracted to the front substrate 1 side are removed. is attracted by the magnet 22 and moves toward the back substrate 2, creating a contrast in the plastic dispersion liquid and forming a display. Next, a blending example of the plastic dispersion liquid of the present invention will be shown.

Formulation Example 1 98 parts of Isopa-1M (isoparaffin solvent manufactured by Etsuo Chemical Co., USA), 1.25 parts of Aerosil 200 (fine powder silicic acid manufactured by Nippon Aerosil Co., Ltd.), and Typeque CR-50 (Ishihara Sangyo Co., Ltd.) (Titanium oxide manufactured by Co., Ltd.)
One copy to T. K. The mixture was mixed with a homomixer (wet dispersion machine manufactured by Tokushu Kika Kogyo Co., Ltd.) to form a white liquid.

40 parts of Todakara Ichi KN-320 (manufactured by Toda Kogyo Co., Ltd.) and Epototo YD-017 (manufactured by Tobu Kasei Co., Ltd.).
25 parts of a 40% methyl ethyl ketone solution of solid epoxy resin (manufactured by Co., Ltd.) was kneaded, dried, pulverized, and dispersed to give 10
30 parts of black magnetic fine particles having a mesh size of 0 to 325 were obtained.
The magnetic fine particles were mixed and dispersed in the white liquid to obtain a plastic dispersion liquid. Formulation Example 2 The same procedure as Formulation Example 1 was carried out except that 1.5 parts of Aerosil 200 was used.

Formulation example 3 Formulation example 1 except for using 1.75 parts of Aerosil 200
I did exactly the same thing.

Formulation Example 4 The same procedure as Formulation Example 1 was carried out except that 2.0 parts of Aerosil 200 was used.

Formulation Example 5 The same procedure as Example 1 was carried out except that 4.0 parts of Aerosil 200 was used.

Combination example 6 85 parts of Isopa M and 15 parts of Benzidine Yellow were mixed with T. K
．． After kneading with a homomixer, 30 parts of the same magnetic fine particles as used in Formulation Example 1 were mixed and dispersed thereto to obtain a plastic dispersion liquid.

Blend Example 7 100 parts of mineral spirits, 6 parts of Silnetx P52 (fine powder silicic acid manufactured by Mizusawa Chemical Industry Co., Ltd.), and 1 part of Taipeiku CR-50 (titanium oxide manufactured by Ishihara Sangyo Co., Ltd.) were added to T.
．． K. A white liquid was obtained by kneading with a homomixer.

Next, 3 parts of a 20% aqueous solution of 24 parts of MRM-400 (gamma hematite manufactured by Toda Kogyo Co., Ltd.) and Gohsenol GM-14 (polyvinyl alcohol manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd.)
Knead 0 parts with three rolls, dry and crush, and make 100 parts.
23 parts of brown magnetic fine particles of ~250 meshes were obtained. The magnetic fine particles were mixed and dispersed in the white liquid to obtain a plastic dispersion liquid. Blend example 8 100 parts of mineral spirits, 3 parts of aluminum oxide C (aluminum oxide manufactured by Nippon Aerosil Co., Ltd.), 1 part of Taipeiku R-550 (titanium oxide manufactured by Ishihara Sangyo Co., Ltd.)
Department, Seika First Erotic 1 2200 (Dainichisei Chemical Industry Co., Ltd.)
0.1 part of yellow pigment manufactured by T. K. After kneading with a homomixer, 30 parts of the same magnetic fine particles as used in Example 1 were mixed and dispersed thereto to obtain a plastic dispersion liquid.

Formulation example 9 100 parts of toluene, 3 parts of Esben (organic bentonite manufactured by Hojun Yoko Co., Ltd.), 1 part of Taipei CR-50, Al
1O Red (red pigment manufactured by Dainichiseika Kagyo Co., Ltd.) 0.2
The part is T. K. After kneading with a homomixer, add 100~
A plastic dispersion liquid was obtained by mixing and dispersing 40 parts of 325 mesh stainless steel powder.

Combination example 10 50 parts of water, 50 parts of ethylene glycol, 10 parts of Aerosil 200, 50 parts of Typeque Yellow TY-1
(Yellow pigment manufactured by Ishihara Sangyo Co., Ltd.) 2.5 parts were thoroughly kneaded in a container using a stirring rod to obtain a yellow liquid.

Next, 30 parts of MRMB-450 (magnetite manufactured by Toda Kogyo Co., Ltd.) and Acrypet K-001 (Mitsubishi Rayon
40 parts of a 20% toluene solution of methacrylic resin (manufactured by Co., Ltd.) was kneaded with three rolls, dried, and pulverized to a powder of 100 to 250.
25 parts of mesh black magnetic fine particles were obtained. The magnetic fine particles were mixed and dispersed in the yellow liquid to obtain a plastic dispersion liquid. Formulation example 11 100 parts of water, 10 parts of Aerosil 200, Taipeiku R-
5501 parts were kneaded in a container using a stirring rod to obtain a white liquid.

Next, 36 parts of stainless steel powder (100-325 mesh),
15 parts of a 40% methyl ethyl ketone solution of Epotote YD-014 (a solid epoxy resin manufactured by Tobu Kasei Co., Ltd.) was mixed with 9 parts of Typeque R-550 and 3 parts of AllO Red, dried, and crushed to form 100 to 325 meshes. 35 parts of red magnetic fine particles were obtained. The magnetic fine particles were mixed and dispersed in the white liquid to obtain a plastic dispersion liquid. Formulation Example 12 One part of Isopa MlOO, 14 parts of light calcium carbonate, and 1 part of Taipaque CR-50 were added to T.I. K. After kneading with a homomixer, add the same magnetic fine particles 30 as used in Formulation Example 1 to this.
The components were mixed and dispersed to obtain a plastic dispersion liquid.

Next, the following table shows the results of a test in which a magnetic panel in which a plastic dispersion liquid was prepared according to the above formulation example was combined with a magnetic means.

Note that a magnetic pen was used as the magnetic means. Each test item was tested as follows.

(1) Yield value of dispersion In the present invention, the yield value is measured by a direct method using a Bruckfield type BL viscometer (manufactured by Tokyo Keiki Co., Ltd.), and the method is as follows.

The rotor of the viscometer is immersed in the plastic dispersion liquid, and only the plastic dispersion liquid is passed around the rotor without rotating the rotor.
．． 2r. m. p. When the rotor is rotated at a very slow speed, the spring of the rotor is also twisted, causing the rotor and the plastic dispersion liquid to rotate together, but when the rotor is twisted to a certain angle, burrs begin to occur between the plastic dispersion liquid and the rotor.
At this time, the torsion angle scale of the rotor is measured, and the yield value is calculated from this torsion angle scale, the torsion constant of the rotor spring, and the shape and area of the rotor. The conversion formula is as follows. However, θ is the scale of the measured rotor torsion angle.

(2) Display clarity Permanent magnet equivalent to JISC25O2MPB38O (dimensions 2
．． 0 x 2.0 x 3 mm, magnetization direction 3n direction),
Visually observe the display when recording at a recording speed of 25 (V7l/Sec).

(3) Contrast between display and background Visually observe the difference in brightness between the color of the entire panel (background) and the display recorded in the same manner as the clarity of display in (2).

(4) Display retention A sufficient magnetic field is applied to the panel to perform recording, the panel is left stationary, and the degree of sedimentation of the magnetic particles is visually observed after a certain period of time.

Vibration (once per second, amplitude 200 m) was recorded on the panel in the same way.
? Visually observe the degree of sedimentation of the magnetic particles when n) is added by hand. (5) Migration of magnetic particles The magnetic field applied to the panel is varied and the recorded density (amount of electrophoresed magnetic particles) is visually observed.

As is clear from the above results, the magnetic panel and magnetic pen of the present invention, which are made by filling a dispersion liquid with a yield value of 5φMw'Cd or more, exhibit excellent performance in all test items and are extremely useful. It was hot.

In addition, the yield value (Dyne/C
wL) is shown in the following table.

[Brief explanation of the drawing]

1 to 5 are explanatory diagrams showing each embodiment of a display device set using magnetic force according to the present invention. FIG. 6 is a diagram showing the relationship between strain rate and stress to explain the yield value of a magnetic panel. 3...Plastic dispersion liquid, 5, 8,
12, 19... Magnetic panel, 7, 14, IT,
18, 20... Printing means.

Claims (1)

[Scope of Claims] 1 (A) A plastic dispersion liquid having a yield value of 5 dyne/cm^2 or more consisting of magnetic fine particles, a dispersion medium, a fine particle thickener, and optionally a colorant is sealed between two substrates. A display device set using magnetic force, which is a combination of a magnetic panel and (B) magnetic means for applying a magnetic field to magnetic fine particles in the plastic dispersion liquid. 2. A display device set using magnetic force according to claim 1, wherein the magnetic means is a magnetic pen. 3 Claim 1 in which the magnetic means is a magnetic head
A display device set using magnetic force as described in Section 1. 4. A display device set using magnetic force according to claim 1, wherein the magnetic means is a printing device having permanent magnet figures and characters on its surface. 5. A display device set using magnetic force according to claim 1, wherein the magnetic means comprises a magnetic sheet having holes in the shape of figures or letters and having a magnetic shielding effect, and a permanent magnet. 6. A display device set using magnetic force according to claim 1, wherein the magnetic means is a dot matrix wire device having a magnet at the tip of the wire.