JP2006208478A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device which can prevent flocculation with time, is high in display performance, and is excellent in durability. <P>SOLUTION: The image display device includes at least one or more magnetic liquids on its support. A medium is provided on the supporting body, and the magnetic liquid is moved inside or outside of the medium by magnetism of a magnetic head 14. The magnetic liquid is an ionic liquid including at least an iron ion and an imidazolium ion. The medium is a porous medium 12, and the magnetic liquid is colored. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technical field of an image display device using a magnetic liquid.

With the spread of digital information, attention has been focused on image display devices that display digital images. Conventionally, liquid crystal displays have been widely used as digital information displays. In particular, a reflective liquid crystal display with low power consumption is promising from the viewpoint of mobile suitability, but has a low reflectance because it uses a polarizing plate and a color filter. Therefore, recently, electrophoretic methods, electrochromic methods, electrodeposition methods, and the like have been proposed as methods that enable display close to paper.
However, in these methods, it is difficult to satisfy all of the contrast ratio, response speed, etc., and development of a new image display device is desired.

On the other hand, it has been proposed to apply a magnetic fluid in which fine particles of a magnetic material are dispersed in a liquid to an image display device (see, for example, Patent Document 1).
However, in the method using a magnetic fluid, magnetic fine particles are likely to aggregate over time. Therefore, development of an image display device that is excellent in durability (stability) over time is desired.
Japanese Patent Laid-Open No. 7-146659

  The present invention has been made in view of the above problems, and an object thereof is to provide an image display device having high display performance and excellent durability.

  Under such circumstances, as a result of intensive studies by the inventors, it has been found that the problems of the present invention can be solved by using the following means.

<1> An image display device comprising at least one magnetic liquid on a support.

<2> The image display device according to <1>, wherein a medium is provided on the support, and the magnetic liquid is moved inside or outside the medium by magnetism.

<3> The image display device according to <1> or <2>, wherein the magnetic liquid is an ionic liquid.

<4> The image display device according to any one of <1> to <3>, wherein the magnetic liquid is an ionic liquid having at least iron ions and imidazolium ions.

<5> The image display device according to any one of <1> to <4>, wherein the medium is a porous medium, and the magnetic liquid is colored.

  The present invention can provide an image display device having high display performance and excellent durability.

  Hereinafter, the present invention will be described in detail. In the present specification, “to” indicates a range including numerical values described before and after the values as a minimum value and a maximum value, respectively.

The present invention is an image display device including at least one magnetic liquid on a support.
The magnetic liquid used in the present invention refers to a liquid exhibiting magnetism, and excludes a magnetic fluid in which magnetic fine particles are dispersed with a surfactant or the like. In the magnetic fluid in a dispersed state, it is difficult to keep the dispersed state of the magnetic fine particles stably and easily aggregates over time, whereas the magnetic liquid of the present invention does not contain magnetic fine particles and is stable over time. . Therefore, the image display device of the present invention using a magnetic liquid is excellent in durability.
The magnetic liquid may be at least one paramagnetic material, diamagnetic material, or ferromagnetic material, but is preferably a ferromagnetic material.

  Examples of the magnetic liquid include a concentrated aqueous solution of a magnetic metal salt and an ionic liquid containing an element exhibiting magnetism described below. In particular, when the magnetic liquid is composed of an ionic liquid, it does not volatilize, which is a preferred embodiment from the viewpoint of improving the stability of the element. The ionic liquid means an ionic compound composed of a cationic compound and an anionic compound and is a liquid. An ionic liquid is a volatile compound corresponding to a vapor pressure, whereas an ionic liquid is expected to be used as a solvent for a functional material as a non-volatile liquid having no vapor pressure.

Any ionic liquid may be used in the present invention.
The cationic compound contained in the ionic liquid is preferably an imidazolium salt compound, a pyridinium salt compound, an ammonium salt compound, a phosphonium salt compound, or the like. Specific examples include 1-ethyl-3-methylimidazolium, 1-n-butyl-3-methylimidazolium, 1-ethyl-3-ethylimidazolium, and the like. Preferably, it is an imidazolium salt compound. More preferred are 1-ethyl-3-methylimidazolium salt compounds and 1-n-butyl-3-methylimidazolium salt compounds.
The anionic compound contained in the ionic liquid preferably contains an element that exhibits magnetism. Examples of the element that exhibits magnetism include iron, cobalt, and nickel, and iron is particularly preferable.

Preferably, the anionic compound containing an element that exhibits magnetism is ferric chloride (III) ion (FeCl ₄ ⁻ ), ferric bromide (III) ion (FeBr ₄ ⁻ ), ferric fluoride (III) ion (FeF ₄ ⁻ ), cobalt chloride (III) ion (CoCl ₄ ⁻ ), nickel chloride (II) acid ion (NiCl ₃ ⁻ ), more preferably iron (III) chloride ion (FeCl ₄ ⁻ ). It is.

In the present invention, it is particularly preferable to use an ionic liquid having at least iron ions and imidazolium ions. For example, 1-butyl-3-methylimidazolium chloride, 1-ethyl chloride ferrate 3-methylimidazolium is mentioned, and among these, chloroferrate-1-butyl-3-methylimidazolium is preferable.
Such an ionic liquid can be synthesized according to the method described in “Chemistry Letters, p1590, 2004”.

The magnetic liquid according to the present invention can be colored by adding a colorant as necessary.
When a dye is used as the colorant, any dye may be used. And pigments. When a pigment is used as the colorant, a perylene pigment, a phthalocyanine pigment, an azo pigment, a diketopyrrolopyrrole pigment, a quinacridone pigment, or a titanium oxide pigment can be used, but the invention is not limited thereto.
The content of the dye in the magnetic liquid is preferably 1% by mass or more and 20% by mass or less, and more preferably 1% by mass or more and 10% by mass or less. The content of the pigment is preferably 1% by mass or more and 20% by mass or less, and more preferably 1% by mass or more and 10% by mass or less.
The magnetic liquid colorant according to the present invention is preferably a dye from the viewpoint of stability over time.

  In addition, various additives can be appropriately added to the magnetic liquid according to the present invention.

  Examples of the support that can be used in the image display device of the present invention include a glass substrate, a metal substrate, and a plastic substrate, and a glass substrate or a plastic substrate is preferable.

  Examples of the plastic substrate include triacetyl cellulose (TAC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), syndiotactic polystyrene (SPS), polyphenylene sulfide (PPS), polycarbonate (PC), and polyarylate. (PAr), polysulfone (PSF), polyestersulfone (PES), polyetherimide (PEI), cyclic polyolefin, polyimide (PI) and the like. Polyethylene terephthalate (PET) is preferable.

  The thickness of the plastic substrate in the present invention is not particularly limited, but is preferably 30 μm to 700 μm, more preferably 40 μm to 200 μm, and still more preferably 50 μm to 150 μm. Further, in any case, the haze is preferably 3% or less, more preferably 2% or less, further preferably 1% or less, and the total light transmittance is preferably 70% or more, more preferably 80% or more, and further preferably 90%. That's it.

  For the plastic substrate in the present invention, known plasticizers, dyes / pigments, antistatic agents, ultraviolet absorbers, antioxidants, inorganic fine particles, peeling accelerators, and leveling agents as long as the effects of the present invention are not impaired as necessary. In addition, a resin modifier such as a lubricant may be added.

In the image display device of the present invention, at least one kind of magnetic liquid is contained on the support, in particular, the medium is provided on the support, and the magnetic liquid is magnetophoresed inside or outside the medium by magnetism. Display.
The magnetic liquid is preferably the ionic liquid described above, and particularly preferably an ionic liquid having at least iron ions and imidazolium ions.

The medium is not particularly limited as long as the magnetic liquid can move in and out of the medium and can maintain the state, but a porous medium is preferable from the viewpoint of display performance. The porous medium used in the present invention may be any medium, and examples thereof include cellulose ester, polyimide resin, phenol resin, glass, porcelain material, and metal. Preferably, it is a cellulose ester.
The porosity of the porous medium may be in any range as long as the magnetic liquid can be moved and retained, but is preferably 30% to 80%, and more preferably 40% to 70%. .
The thickness of the porous medium is preferably 50 μm to 300 μm, and more preferably 100 μm to 200 μm.

  The display method in the image display apparatus of the present invention is performed by causing a magnetic liquid to be magnetized into or out of the medium by magnetism. Magnetism may be applied to the entire surface of the display screen, or a magnetic head may be scanned. Further, the image display medium of the present invention may be conveyed in a fixed magnetic head. The image display device of the present invention may be either reversible display or irreversible display, but is preferably reversible display. A single color display may be used, or a multi-color display in which the color is changed for each place may be used.

When the medium is a porous medium and the magnetic liquid is colored, in the image display device of the present invention, a state in which the colored magnetic liquid is present on the surface of the porous medium and the magnetic inside or the back surface of the porous medium are present. Display can be performed by reversibly changing the state in which the liquid is present by magnetophoresis. FIG. 1 outlines the display method of the image display apparatus of the present invention.
FIG. 1A shows a display state. Since the colored magnetic liquid 10 is present on the surface of the porous medium 12 on the viewer side, it is colored. On the other hand, FIG. 1B shows a non-display state. Since the colored magnetic liquid 10 exists inside the porous medium 12 or on the back surface of the porous medium as viewed from the observer, no color is displayed.

Although the structural example in the image display apparatus of this invention is shown in FIG. 2, this invention is not limited by this.
In FIG. 2, the porous medium 12 is provided as a common area extending over the entire display screen, but the porous medium 12 may be provided separately. In the case where the porous medium 12 is provided as a common area, the partition 18 is provided on the porous medium 12 so that the magnetic field generated by the magnetic head 14 or the like hardly affects the adjacent magnetic liquid. It is preferable to do. Further, a protective film 16 is provided on the upper part of the partition wall 18.
When a magnetic field is generated from the protective film 16 side by the magnetic head 14 or the like, the colored magnetic liquid 10 moves to the space 20 partitioned by the partition wall 18 and the protective film 16 and exhibits a color. When a magnetic field is generated on the porous medium 12 from the side opposite to the protective film 16, the colored magnetic liquid 10 moves to the inside of the porous medium 12 and is scattered by light scattering of the space 20 and the protective film 16. The color disappears.

  The material of the partition wall 18 is not particularly limited, but a polymer such as polymethyl methacrylate or polystyrene can be used. The height of the partition wall 18 (the distance between the porous medium 12 and the protective film) is not particularly limited, but is preferably 10 μm to 200 μm, more preferably 20 μm to 100 μm. Although the thickness in particular of the partition 18 is not restrict | limited, 5 micrometers-100 micrometers are preferable, More preferably, they are 5 micrometers-20 micrometers. Although the arrangement | positioning space | interval of the partition 18 is not restrict | limited in particular, 50 micrometers-500 micrometers are preferable, More preferably, they are 80 micrometers-200 micrometers.

The protective film 16 can also have a function as a support. The material of the protective film 16 is not particularly limited, but those exemplified as the support are preferable, and in particular, a glass substrate or a plastic substrate subjected to uneven surface scattering processing is preferable. Further, in order to impart water repellency, light resistance, and oil repellency to the protective film 16, a water repellent, a oil repellant, an antireflection film, a UV cut film, or the like may be applied to the surface of the protective film 16.
Although the thickness in particular of the protective film 16 is not restrict | limited, 10-300 micrometers is preferable, More preferably, it is 10-200 micrometers.

  The image display device of the present invention can be suitably used as a display device for digital information, a computer, a clock, a calculator, and the like.

  The present invention will be described more specifically with reference to the following examples. The materials, reagents, substance amounts and ratios, operations, and the like shown in the following examples can be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention is not limited to the following specific examples.

<Example 1>
The colored magnetic liquid, 1-butyl-3-methylimidazolium ferrate, was synthesized according to the method described in the literature (Chemistry Letters, page 1590, 2004).

A schematic diagram of the produced image display apparatus is shown in FIG.
As the porous medium 12, a micro filter manufactured by Fuji Photo Film was used. The colored magnetic liquid 10 was applied on the microfilter and allowed to stand, thereby allowing the colored magnetic liquid to penetrate into the porous film so as to be 20 g / m ² .
On the porous medium 12, a partition wall 18 made of polymethylmethacrylate (Mortex) was provided. A glass substrate (manufactured by Asahi Glass Co., Ltd.) subjected to uneven surface scattering processing was installed on the upper part of the partition wall 18. In order to impart water repellency to the glass substrate surface, a water repellent (Cytop, manufactured by Asahi Glass Co., Ltd.) was applied.

When a magnetic head is applied to this image display device from the glass substrate side so that a magnetic field of H = 2, 10 kG (1T) is applied, the magnetic field is visually colored to black from the scattered white background. Behavior was observed. That is, it was confirmed that the display material of the present invention undergoes magnetic field migration in the porous medium by the action of the magnetic field, and as a result, is colored.
Next, when a magnetic head was placed on the back side of the glass substrate of the image display device and a magnetic field was applied, a behavior of changing from a colored state to a scattered white background was observed. When the colored magnetic liquid moves into the porous medium by magnetophoresis, a space is created between the uneven portion of the upper transparent glass and the porous medium, and as a result, light is scattered by the uneven portion of the upper glass substrate. Based on the scattered white background was observed.

  When this operation was repeated 100 times, no deterioration in display performance was observed especially visually, and it was confirmed that the image display device in this example was excellent in repeated stability.

It is the schematic which shows the display method of the image display apparatus of this invention, (A) shows a display state, (B) shows a non-display state. It is a schematic diagram which shows the structural example of the image display apparatus of this invention. It is a schematic diagram of the image display apparatus in an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Colored magnetic liquid 12 Porous medium 121 Porous medium 14 which colored magnetic liquid penetrate | infiltrated 14 Magnetic head 16 Protective film 161 Glass substrate 162 Water-repellent film 18 Partition 20 Space

Claims (5)

  An image display device comprising at least one magnetic liquid on a support.   The image display apparatus according to claim 1, further comprising a medium on the support, wherein the magnetic liquid is moved inside or outside the medium by magnetism.   The image display device according to claim 1, wherein the magnetic liquid is an ionic liquid.   4. The image display device according to claim 1, wherein the magnetic liquid is an ionic liquid having at least iron ions and imidazolium ions. 5.   The image display device according to claim 1, wherein the medium is a porous medium, and the magnetic liquid is colored.

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