JPH0331891A - Magnetic powder migration multicolor display device - Google Patents

Abstract

PURPOSE:To realize a multicolor display at low cost by massproduction by coating magnetic powder of large size which is large in magnetic permeability and magnetic powder of small size which is small in magnetic permeability in different colors, and providing a sizing net between a couple of substrates where the mixed white turbid liquid of both the kinds of magnetic powder is sealed. CONSTITUTION:When a write information signal is inputted to a driving circuit 12, the circuit 12 sends an excitation signal to a driving transistor(TR) 11 to drive a write electromagnet 10. When such an exciting current that the magnetic powder 1 of large size which is large in magnetic permeability is attracted and the magnetic powder of small size which is small in magnetic permeability is not attracted is supplied to the electromagnet 10, the magnetic powder 1 of large size painted in red moves in the white turbid liquid and is arrayed on the sizing net 7, so that a red pattern is observed through a surface substrate 9. Then when an exciting current which attracts even the magnetic powder 2 of a small size is supplied to the electromagnet 10, the magnetic powder 2 of small size painted in black passes through the sizing net 7 and is arrayed on the reverse surface of the surface substrate 9 to make a black display. For erasure, a rod magnet 14 for erasure on the back surface of a back substrate 4 is moved to attract both of the magnetic powder 1 and magnetic powder 2 to the substrate 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to large-sized display devices, and more particularly, to multicolor electrophoretic display devices that use magnetic particles to display high-contrast bit images.

[Prior Art] Conventionally known magnetic particle migration display devices have a structure in which black magnetic particles are mixed into a white turbid liquid and written using an array of electromagnets. I have no messenger.

[Problem to be Solved by the Invention] The problem to be solved by the present invention is to provide a structure that enables display of at least two or more colors in a magnetic particle migration display device that displays using magnetic particles. and
An object of the present invention is to propose a multicolor magnetophoretic display device that solves the above-mentioned problems using a comparatively inexpensive and efficient method.

[: Means for Solving Problem A J In order to solve the above problem, the magnetophoresis multicolor display device of the present invention uses fine-grained magnetic particles and large-grained magnetic particles having a particle size several times or more larger than the fine-grained magnetic particles. This white turbid liquid is sealed between a non-magnetic front substrate and a non-magnetic back substrate, a movable writing electromagnet array is arranged roughly on the front substrate, and a bar-shaped column is placed behind the back substrate. An erasing permanent magnet is arranged, and the fine-grained magnetic powder and the large-grained magnetic powder are small so that they have different colors. is provided inside the surface substrate at a position corresponding to several times the particle diameter of the fine-grained magnetic powder, and the magnetic permeability of the υl-diameter magnetic powder is much larger than the magnetic permeability of the fine-grained magnetic powder. It is characterized by being made of a combination of magnetic materials.

[Function] As described above, the magnetic particle migration display device of the present invention utilizes two types of magnetic particles with different particle sizes. The other magnetic powder should also have a distinctive color scheme.Generally, the magnetic powder with a large particle size is colored by electrodeposition, vapor deposition, spraying, penetrating coloring, or reactive coloring. Select the magnetic powder material so that the magnetic permeability is much larger than that of small magnetic particles.

The purpose of providing a difference in magnetic permeability is simply to differentiate the magnitude of magnetic force in a uniform magnetic field, so a material with a large absolute value of magnetic permeability is not necessarily required. Therefore, if you want to produce large-grained magnetic powder and fine-grained magnetic powder based on the same material, it is possible to lower the average magnetic permeability per volume by kneading resin etc. into the fine-grained magnetic powder. It is. As described above, when a magnetic field is applied to two or more types of magnetic particles with large differences in magnetic permeability, the lines of magnetic force concentrate on the material with high magnetic permeability, and as a result, a relatively large magnetic force acts on the large-sized magnetic particles with high magnetic permeability. , this large-sized magnetic powder is first moved in the turbid liquid by being attracted by the magnetic field. However, the size of the particle directly affects the fluid resistance.1. Furthermore, since the weight varies, it cannot be said that large particle diameter magnetic particles are easy to move. Therefore, in order for the large-grain magnetic particles to move ahead of the fi-diameter magnetic particles, the above-mentioned difference in magnetic permeability must be large enough to compensate for the handicaps of volume and electric charge. For this reason, it is advantageous that the specific gravity of the material for the large particle size magnetic powder is smaller than the specific gravity for the fine particle size magnetic powder.

As mentioned above, large-sized magnetic particles start moving first, so selective movement (pulling) of magnetic particles is possible by appropriately selecting the magnitude of the applied magnetic field. Therefore, large-sized magnetic particles are not allowed to pass through.・If a mesh mesh that allows fine-grained magnetic particles to pass through is placed in the suspension as a sizing net, only the fine-grained magnetic particles can move freely from the front substrate to the back substrate regardless of the sizing net. By arranging the particle sizer net at an appropriate distance from the transparent surface substrate, large-sized magnetic particles captured by the particle sizer net can be clearly seen through the turbid liquid, and the distance between the particle sizer net and the surface substrate can be clearly seen. It is possible to have fine-grained magnetic powder present in the gaps between the two.

The non-magnetic surface substrate is a transparent flat plate made of glass or plastic, and a surface treatment layer that is easily charged, such as polyimide, which easily generates electrostatic force between magnetic particles, is deposited or coated on the inner surface to enhance the retention of magnetic particles. Form by a method such as attaching. The back substrate does not need to be transparent, but must be made of the same (non-magnetic) material.The inner surface of this back substrate should also be provided with the above-mentioned surface treatment layer.Also, the material of the particle sizing net should be a resin material that easily retains magnetic particles. or apply polyimide, etc.

First, an example will be given of the operation of displaying red and black on a white surface. In this case, the large-sized magnetic particles are colored red, the fine-sized magnetic particles are colored black, and the cloudy liquid is literally white (and cloudy to the extent that it cannot be seen up to the back substrate). Write electromagnet arrays are arranged on the surface at a sufficiently fine pitch, and a drive circuit is provided to individually excite each write electromagnet. The write electromagnet supplied with an excitation current attracts the large red magnetic particles held on the back substrate and holds them on the sizing net.In this case, the sizing net sufficiently covers the surface substrate. If the net is placed close to the net, the red magnetic powder will be seen through the surface substrate without being affected by the cloudy liquid at all.Of course, if the sizing net is also transparent, the contrast will be further improved.

7. If the write electromagnet is supplied with an excitation current sufficient to attract fine magnetic particles from the drive circuit, it will attract both black and red magnetic particles, but the black fine magnetic particles will pass through the sizing net and be dispersed. The red magnetic particles are hidden behind the black and cannot be seen, so they are displayed as black. A write electromagnet that does not carry an excitation current does not attract magnetic particles, so you will see the white of the cloudy liquid. In this way, the write electromagnet array is selectively driven according to the pattern desired to be displayed, and when writing of one row is completed, it is moved one pitch to write the next row. In this way, a pattern consisting of black, red and black is written on the entire display surface. Erasing is carried out by moving a sufficiently strong erasing permanent magnet rod from the rear surface to simultaneously attract and hold both the black and red magnetic particles inside the rear substrate. It goes without saying that it is desirable that the writing boron array and the erasing permanent magnet described above be moved electrically.

Hereinafter, the present invention will be explained based on Examples.

[Example] FIG. 1 is a cross-sectional view of a magnetic particle migration multicolor display device according to the present invention in an 11" x 1 configuration.

The large-grain magnetic powder 1 and the fine-grain magnetic powder 2 are retained on the surface treatment layer 5 inside the rear substrate 4, as shown in the erased state. These magnetic particles are mixed into the cloudy liquid 3, and in order to prevent the enclosed magnetic particles from being concentrated in one place between the back substrate 4 and the front substrate 90, a honeycomb-like grid-like separation wall 6 is inserted into a sizing net 7. and the rear substrate 40. The particle sizing net 7 is a mesh size that does not allow the large-sized magnetic particles 1 to pass through, but allows the fine-sized magnetic particles 2 to pass through, and is arranged near the surface substrate 9. If this particle size sizing net 7 comes into close contact with the surface substrate 9, the fine magnetic particles 2 will not be held inside the surface substrate 9. 2. Fine particle size magnetic powder in the form of a honeycomb or grid pattern.
It also plays the role of separating so that they do not exist unevenly. 1
0 is a write electromagnet, and 11 is a driving transistor for the electromagnet. The writing electromagnets 10 are arranged at a pitch according to the display purpose, but relatively speaking, the display purpose cannot be achieved unless the pitch is sufficiently large compared to the busy diameter of the large particle diameter magnetic powder 1. . The pattern generator 13 is a circuit that generates characters and pictures to be displayed in the form of an information string corresponding to one dot of the writing electromagnet, and the signal information necessary for one write cycle is sent to the drive circuit 12 to set the timing. The drive circuit 12 supplies an excitation signal to the drive transistor 11. This drive circuit 12 is formed from a simple shift register and latch circuit. If you want to erase the display pattern, erase it by sliding the erasing permanent magnet 14 on the back 11i substrate.Although not shown in the drawing, in order to seal the cloudy liquid 3 between both thread plates, Needless to say, a sealing portion is provided around the substrate.

FIG. 2 is a graph showing the magnetic field movement characteristics of two types of magnetic particles used in the display device of the present invention.

A curve 15 is a curve of the magnetic field movement characteristic of the large particle size magnetic powder 1, and a curve 16 is a curve of the magnetic field movement characteristic of the fine particle size magnetic powder 2. 2
There is a deviation in the magnetic field movement characteristic curve of seed magnetic particles as shown in Figure 2, and if the writing electromagnet is excited with a strength that generates magnetic field A at the position inside the substrate on the opposite side, large particle diameter magnetic particles 1
If only the magnetic field B moves and is excited with a strength that generates a magnetic field B,
Both magnetic particles move. The threshold value of this movement characteristic is determined by the coercive force on the substrate surface and the magnetic properties of the magnetic particles.In the case of erasing, a permanent magnet capable of generating a magnetic field C may be brought close to the opposite position. - Once erased, the permanent magnets will grow from the substrate surface and will not interfere with the next writing. As can be seen from this embodiment, once writing or erasing is performed on the magnetic particle migration display device, the display can be maintained as is.

[Effects of the Invention] As described above, the magnetophoresis multicolor display device of the present invention has the following effects:
Since power is consumed only when writing, it is suitable for purposes that display the same pattern for a relatively long period of time, such as advertising signboards and bulletin boards. However, in the past, only monochrome display was possible, which had the disadvantage that it could not be used sufficiently for purposes such as advertisements. Originally, magnetic particle phoresis display devices had high contrast, but the magnetic particle phoresis display device of the present invention Color display devices can display two or more colors, so they can bring out good contrast more effectively.
It is the best display device for various long-term display purposes, and its industrial use effect is great.

[Brief explanation of drawings]

Figure 1 shows the configuration of the magnetic particle migration multicolor display device of the present invention +1 Jr.
It is a front view. FIG. 2 is a graph showing the magnetic field movement characteristics of magnetic particles used in the magnetic particle migration multicolor display device of the present invention.・・・・・・・・・Large particle size magnetic powder・・・・・・Fine particle size magnetic powder・・・・・・Cloudy liquid・・・・・・Back substrate・・・・・・・・Separation wall・・・・Grain sizing net・・・Strut・・・Surface substrate 0・・・・・Write Included electromagnet 5...Large particle size magnetic powder movement curve 6...Fine particle size magnetic particle movement curve

Claims (1)

[Claims] A fine-grained magnetic powder, a large-grained magnetic powder having a particle size several times larger than the fine-grained magnetic powder, and a cloudy liquid containing both magnetic particles are sealed between a transparent non-magnetic front substrate and a non-magnetic back substrate, In the display body for moving magnetic particles, which includes a movable write electromagnet array arranged on the front substrate and a bar-shaped erasing permanent magnet arranged behind the rear substrate, the large particle diameter magnetic particles and the fine particle diameter magnetic particles are arranged. Color-coating is applied to at least one of the magnetic particles so that they are different colors that stand out from each other, and a mesh size sizing net that does not allow only the large-sized magnetic particles to pass is placed inside the surface substrate to match the number of particles of the fine-sized magnetic particles. 1. A magnetic particle migration multicolor display device, characterized in that the magnetic particle migration multicolor display device is made of a combination of magnetic materials provided at positions corresponding to twice the size of the magnetic particles, such that the magnetic permeability of the large particle size magnetic particles is much larger than the magnetic permeability of the fine particle size magnetic particles.