JP4578888B2 - Image display device - Google Patents

Description

  The present invention relates to an image display device, and more particularly, an image display device in which particles are enclosed in a gap between a pair of substrates arranged opposite to each other, and the particles are moved by an electric field applied between the substrates to display an image. It is about.

Conventionally, for example, as shown in Patent Documents 1 and 2, particles are enclosed in a gap between a pair of substrates arranged opposite to each other, and the particles are moved by an electric field applied between the substrates to display an image. Image display devices are known. Further, in this type of image display device, as disclosed in Patent Document 2, a proposal has been made to improve the stability of particle movement by keeping the humidity of the gas filling the gap below a predetermined value. Yes.
JP 2002-107771 A JP 2003-167278 A

  By the way, in the conventional image display device having the above-described structure, problems such as low repetition durability and difficulty in obtaining stable density contrast and poor image display reproducibility and stability are recognized.

  The present invention has been made in view of the above circumstances, and in an image display device that displays an image by moving particles enclosed in a gap between a pair of substrates by an electric field, repeated durability, image display reproducibility, and image The purpose is to improve the stability of the display.

  In the image display device according to the present invention, as described above, particles are enclosed in a gap between a pair of substrates arranged opposite to each other, and the particles are moved by an electric field applied between the substrates to display an image. In the apparatus, an insulating gas is sealed in the gap.

Here, as the insulating gas, for example, at least one of SF ₆ gas, CO ₂ gas, nitrogen gas, and dry air having a water content of 3000 ppm or less can be preferably used. The pressure of the insulating gas sealed within the gap is a value that exceeded the atmospheric pressure (approximately 0.101 MPa).

  The basic configuration of the image display apparatus of the present invention will be described in detail below.

[Action mechanism]
First, an operation mechanism of this type of image display apparatus will be described. At least two or more kinds of particles sealed in a gap between a pair of substrates arranged opposite to each other are mixed and stirred in a stirring container at a predetermined ratio. In this process of mechanical stirring and mixing, friction charging is performed between the particles and between the particles and the inner wall of the container, and each particle is considered to be charged. Thereafter, the mixed particles are sealed in a gap between the pair of substrates so as to have a predetermined volume filling rate. The encapsulated particles reciprocate between the substrates according to the electric field by switching the polarity of the DC voltage applied between the pair of substrates or by applying the AC voltage (initialization step). Even in the process of this initialization process, each particle is considered to collide and frictionally charge between particles and between the particle and the substrate surface layer. In addition, a desired triboelectric charge amount can be obtained by this initialization process.

  Due to the frictional charging, at least one of the particles is positive (hereinafter, positively charged particles are referred to as first particles), and at least one of the other particles is negative (hereinafter negatively charged particles). Called the second particles), each charged and trying to adhere and agglomerate between the particles due to the Coulomb attractive force between the first and second particles, but the electric field applied at the end of this initialization step. The particles are separated according to the direction of and attached to one substrate.

  Next, by applying an electric field according to the image signal, the first particles and the second particles are separated and moved in accordance with the electric field and are attached to different substrates. That is, the electrostatic force acting on each charged particle by an externally applied electric field is superior to the Coulomb force between each particle, the image force between the particle and the substrate surface, or the force due to the contact potential difference. For example, it is considered that each particle separates and moves to the opposite substrate.

  The particles adhering to the substrate surface are considered to be adhered and fixed to the substrate surface by mirror image force or van der Waals force generated between the substrate surface. Here, when the chargeability of each particle is high, the cohesive force between the particles becomes high and separation becomes difficult. In addition, particles with high chargeability have high adhesion to the substrate surface, and the probability of being fixed to the substrate surface without moving by the applied electric field increases. When the highly charged aggregated particles are separated, there is a possibility of local discharge, and it is considered that the chargeability of each particle becomes unstable.

  On the other hand, when the chargeability of the particles is low and there is almost no difference in chargeability between the first particles and the second particles, the particles are loosely agglomerated without being separated by an electrostatic force due to an external electric field. Keep the state. As described above, in order to separate particles of different polarities by an external electric field, it is important that each particle has an appropriate charge amount and has triboelectric charging characteristics such that there are few reverse polarity chargeable particles. I know that there is.

  Next, when the particles are moved repeatedly with the polarity of the electric field switched, the chargeability of the particles increases due to the friction between the particles and the friction between the particles and the substrate surface. In some cases, the particles may adhere to the substrate surface layer and cannot be separated. At this time, the charge amount of the particle group causing the image unevenness is broad from a high value to a low value. Therefore, in order to maintain the initial operation state, it is considered important that the change in the charging characteristics of the particles is small.

  As a method for controlling the charging, there is a method of controlling by making fine particles such as inorganic oxide fine particles and resin fine particles exist on the particle surface. However, the collision between the first particles and the second particles, or rubbing, Problems such as transfer of fine particles to counterpart particles (first particles or second particles) and / or decrease of charge amount due to transfer to transparent electrode substrate, decrease of display contrast due to change of powder fluidity, etc. Is caused. Avoiding such a change in the positional relationship between the surface of the first particle or the second particle and the fine particle is to maintain the chargeability of the first particle and the second particle and to maintain the fluidity. is important.

  The above description has been made on the assumption that the first particles that are positively charged and the second particles that are negatively charged are each one type. There is no problem even if there are two or more types.

[Particle composition]
The particles in the image display device of the present invention are composed of at least a color material, a charge control agent, and a resin. However, the color material may also serve as a charge control agent. Examples of the color material used in the present invention include the following.

  Examples of the black color material include carbon black, titanium black, magnetic powder, oil black, organic and inorganic dye / pigment black materials. Examples of white color materials include white pigments such as rutile titanium oxide, anatase titanium oxide, zinc white, lead white, zinc sulfide, aluminum oxide, silicon oxide, and zirconium oxide.

  In addition, examples of the chromatic color material include phthalocyanine, quinacridone, azo, condensation, insoluble lake pigments, and inorganic oxide pigments. Specifically, aniline blue, calcoil blue, chrome yellow, ultramarine blue, deyupon oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 185, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3 can be exemplified as a representative one.

  One of the positively and negatively chargeable particles is white, in other words, the colorant in one of the positively and negatively chargeable particles in the present invention is preferably a white color material. By making one particle white, the coloring power and density contrast of the other particle can be improved. At this time, titanium oxide is preferable as a color material for making one of the particles white. By using titanium oxide as the color material, the hiding power can be increased in the range of visible light wavelength, and the density contrast can be further improved.

  As the resin constituting the particles, polyvinyl resins such as polyolefin, polystyrene, acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, vinyl chloride, polyvinyl butyral; vinyl chloride-vinyl acetate copolymer; styrene-acrylic acid Copolymers; straight silicone resins composed of organosiloxane bonds and modified products thereof; fluorine resins such as polytetrafluoroethylene, polyvinyl fluoride, and polyvinylidene fluoride; polyesters, polyurethanes, polycarbonates; amino resins; epoxy resins, etc. . These may be used alone or in combination with a plurality of resins. These resins may be cross-linked. Further, a known binder resin known as a main component for conventional electrophotographic toner can be used for the particles without any problem. In particular, it is preferable to use a resin containing a crosslinking component.

  As the particle sizes of the two colors (for example, white particles and chromatic particles such as blue) that can be positively and negatively charged, it is preferable that the particle sizes and distributions of both particles are substantially equal. By making the particle sizes and distributions of both particles substantially equal, an adhesion state like a so-called two-component developer in which large-sized particles are surrounded by small-sized particles is avoided. A chromatic color density is obtained. If there is a large or small difference between the particle sizes of the two particles, the small particle size particles adhere to the periphery of the large particle size particles, leading to a reduction in the original color density of the large particle size particles, which is not preferable.

  Further, since the color contrast also changes depending on the mixing ratio of the two color particles, it is desirable that the mixing ratio is such that the number of the two color particles is equal or close when the particle diameters are approximately equal. . If the number of particles of two colors deviates greatly, the color of particles having a high ratio becomes strong. However, this is not the case when it is desired to provide contrast between the same color with a dark tone display and a light tone display, or when it is desired to display with a color created by mixing two kinds of particles. The particle diameter of the particles in the present invention cannot be generally described, but in order to obtain a good image, it is preferably about 1 to 100 μm, more preferably about 3 to 30 μm. Dispersion is preferred.

  The shape of the particles is preferably close to a true sphere. In the case of a particle close to a true sphere, the contact between the particles is almost a point contact, and the contact between the particle and the inner surface of the substrate is almost a point contact. Adhesive force based on Waals force is reduced. Therefore, even if the inner surface of the substrate is a dielectric, it is considered that the charged particles can move smoothly in the substrate by the electric field.

  Examples of the method for producing the particles include wet production methods such as suspension polymerization, emulsion polymerization, and dispersion polymerization, which are known as methods for producing electrophotographic toners, and conventional pulverization and classification methods. The particles obtained by the wet manufacturing method are spherical particles, but the particles obtained by the pulverization classification method are irregular particles. In this case, it is desirable to perform heat treatment in order to make the shape of these particles uniform.

[Substrate structure]
The substrate constituting the image display device of the present invention is a pair of opposed substrates, and the particles are enclosed in a gap between the pair of substrates. In the present invention, the substrate is a conductive plate-like body (conductive substrate), and in order to have a function as an image display medium, at least one of the pair of substrates is a transparent conductive substrate that is transparent. It is necessary to be. At this time, the transparent conductive substrate becomes a display substrate.

  The conductive substrate may be conductive, or may be a conductive surface of an insulating support, and may be crystalline or amorphous. Examples of the conductive substrate in which the substrate itself is conductive include metals such as aluminum, stainless steel, nickel, chromium, and alloy crystals thereof, and semiconductors such as Si, GaAs, GaP, GaN, SiC, and ZnO.

  Examples of the insulating support include a polymer film, glass, quartz, and ceramic. Conductive treatment of the insulating support is performed by vapor deposition, sputtering, ion plating, or the like using the metal or gold, silver, copper, etc. mentioned in the specific example of the conductive substrate in which the substrate itself is conductive. A film can be formed.

  As the transparent conductive substrate, a conductive substrate in which a transparent electrode is formed on one surface of an insulating transparent support, or a transparent support having its own conductivity is used. Examples of the transparent support having its own conductivity include transparent conductive materials such as ITO, zinc oxide, tin oxide, lead oxide, indium oxide, and copper iodide.

Insulating transparent supports include transparent inorganic materials such as glass, quartz, sapphire, MgO, LiF, and CaF ₂ , and transparent organic resins such as fluorine resin, polyester, polycarbonate, polyethylene, polyethylene terephthalate, and epoxy. A film or plate-like body, optical fiber, selfoc optical plate or the like can also be used.

  As a transparent electrode provided on one side of the transparent support, a transparent conductive material such as ITO, zinc oxide, tin oxide, lead oxide, indium oxide, copper iodide is used, and by a method such as vapor deposition, ion plating, sputtering, etc. A formed one or a thin one made of metal such as Al, Ni, Au or the like so as to be translucent by vapor deposition or sputtering is used.

  In these substrates, since the surface on the opposite side affects the charged polarity of the particles, it is preferable to provide a protective layer having an appropriate surface state. This protective layer can be selected mainly from the viewpoints of adhesion to the substrate, transparency, and the charge train, as well as low surface contamination. Specific examples of the material for the protective layer include polycarbonate resin, vinyl silicone resin, and fluorine group-containing resin. The resin is selected in such a manner that the constitution of the main monomer of the particles to be used and the difference in frictional charge from the particles are small.

  According to the research of the present inventor, the problem of the conventional apparatus that the repetition durability, the image display reproducibility and the image display stability are inferior is locally between the electrodes when a voltage is applied between the pair of substrates. It has been found that this is caused by the occurrence of electrical breakdown due to electrical discharge, the change of physical properties of particles and the substrate wall due to the electrical discharge, and the generation of active species such as ozone.

  In the image display device of the present invention, in view of the above knowledge, the insulating gas is sealed in the gap between the substrates, so that the discharge between the substrates is suppressed. Therefore, it is possible to prevent dielectric breakdown due to this discharge, change in physical properties of particles and substrate walls, and generation of active species such as ozone, and repeat durability, image display reproducibility and image Display stability can be improved.

  The discharge start voltage (spark voltage) is a function of only the product of the pressure P of the interelectrode gas and the interelectrode distance d according to Paschen's law. According to this law, the higher the pressure P of the interelectrode gas, the higher the discharge start voltage, that is, the less likely discharge occurs. Therefore, if the insulating gas to be sealed is the same, the pressure P is preferably set high. .

  In the conventional apparatus, the air gap between the substrates is filled with atmospheric pressure air. However, even if air exceeding atmospheric pressure (about 0.101 MPa) is sealed instead, discharge can be made difficult to occur. In that case, in general, if the air pressure is about 0.11 MPa or more at 20 ° C., a remarkable discharge suppressing effect can be obtained.

  In addition, instead of filling the space between the substrates with normal air, even if dry air is sealed therein, it is possible to make the discharge difficult to occur. In that case, in general, if dry air having a water content of 3000 ppm or less is used, a remarkable discharge suppressing effect can be obtained.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a partially broken schematic side view showing an image display device according to an embodiment of the present invention. As shown in the figure, this image display device is composed of an image display medium 10 and voltage generation means 20. The image display medium 10 includes a display substrate 8, blue particles 22, white particles 24, a non-display substrate 18, and spacers 26. The display substrate 8 is configured by sequentially laminating the transparent electrode 4 and the protective layer 6 on one side of the transparent support 2. Similarly, the non-display substrate 18 is sequentially laminating the electrode 14 and the protective layer 16 on one side of the support 12. Has been configured. Further, the transparent electrode 4 of the display substrate 8 is connected to the voltage generating means 20, and the electrode 14 of the non-display substrate 18 is grounded.

  Next, details of the image display medium 10 will be described. For example, a 7059 glass substrate with an ITO transparent electrode of 50 mm × 50 mm × 1.1 mm is used for the transparent support 2 and the transparent electrode 4 and the support 12 and the electrode 14 that constitute the outside of the image display medium 10. Note that the support 12 and the electrode 14 on the non-display substrate 18 side are not necessarily transparent. On the inner surface (the surface of the transparent electrode 4 and the electrode 14) in contact with the glass substrate particles, for example, protective layers 6 and 16 are formed by coating polycarbonate resin (PC-Z) with a thickness of 5 μm.

  The spacer 26 is formed such that a square cutout 26 a of 15 mm × 15 mm is provided at the center of a 40 mm × 40 mm × 0.3 mm silicone rubber plate, and a gap 30 is formed between the substrates 8 and 18 after assembly of the device. It is a thing. That is, the spacer 26 is configured by installing the silicone rubber plate provided with the cutout 26a on the surface of the non-display substrate 18 on which the electrode 14 and the protective layer 16 are formed.

  About 15 mg of mixed particles composed of the blue particles 22 and the white particles 24 are screened through the screen into the space formed by the cutouts 26 a of the spacers 26. Thereafter, the display substrate 8 is brought into close contact with the spacer 26 so that the surface on which the transparent electrode 4 and the protective layer 6 are formed faces the non-display substrate 18, and the substrate 8, 18 is pressed and held with a double clip. Then, the spacer 26 and the substrates 8 and 18 are brought into close contact with each other to form the image display medium 10.

When the spacer 26 and the substrates 8 and 18 are brought into close contact with each other as described above, an insulating gas in which CO ₂ gas and nitrogen gas are mixed at a volume ratio of 1: 1 is used as the substrates 8 and 18. It encloses in the space 30 between.

  When a DC voltage of 150 V is applied to the transparent electrode 4 of the display substrate 2 of the image display medium 10 by the voltage generating means 20, a part of the negatively charged white particles 24 on the non-display substrate 18 side has an electric field. When the DC voltage of 500 V is first applied to the display substrate 8 due to the action, many white particles 24 move to the display substrate 8 and the display density is almost saturated. At this time, the blue particles 22 positively charged move to the non-display substrate 18 side. Thereafter, even when the voltage applied by the voltage generating means 20 was set to 0 V, the white particles 24 attached to the display substrate 8 did not move and the display density did not change.

  As a comparative example, an image display device in which the air between the substrates 8 and 18 was filled with air as an ambient atmosphere without sealing the insulating gas was produced. In the image display device of this comparative example, the configuration is the same as that of the above embodiment except that the insulating gas is not sealed.

  In the image display device of the comparative example, dielectric breakdown was observed when a DC voltage of 700 V was applied to the transparent electrode 4. Considering this phenomenon, an electric field is applied to a portion such as a minute void defect or unevenness of the protective layer 6, unevenness of the side wall (inner surface of the spacer 26) between the substrates, unevenness due to particle deviation formed in the blue particle 22 layer, and the like. Concentrated and a small amount of current flows locally above a certain electric field, whereby the insulator constituting the substrates 8 and 18 deteriorates or this local breakdown progresses, leading to dielectric breakdown. it is conceivable that.

  On the other hand, in the image display device according to the present embodiment, no dielectric breakdown was observed even when a DC voltage of 700 V was applied to the transparent electrode 4 in the same manner. Furthermore, in the image display apparatus according to the present embodiment, it has been found that the discharge between the substrates 8 and 18 is also suppressed. Therefore, it is possible to prevent dielectric breakdown due to this discharge, change in physical properties of particles and substrate walls, and generation of active species such as ozone, and repeat durability, image display reproducibility and image Display stability can be improved.

Instead of the above-mentioned mixed gas of CO ₂ gas and nitrogen gas, dry air having a moisture content of 3000 ppm or less at 1.2 atm (about 0.13 MPa) at 20 ° C. is used as the gap 30 between the substrates 8 and 18. Even in the configuration enclosed in the case, basically the same effect as described above can be obtained.

  From the above-mentioned Paschen's law, as the distance d between the electrodes 4 and 14 is increased, the discharge is less likely to occur. However, if the distance d is increased too much, the image display device becomes thicker and the electric field is weakened so that a high drive voltage is obtained. Inconvenience that it is necessary also arises, so it is necessary to set the distance d in consideration of such circumstances. At present, the distance d between the electrodes is about 0.1 to 0.2 mm.

  Here, an example of producing particles used in the image display device of the present invention will be described in detail.

(White particles-1)
a) Preparation of Dispersion A ··· Styrene monomer: 53 parts by weight · Titanium oxide (TYPECR CR63: manufactured by Ishihara Sangyo Co., Ltd.): 45 parts by weight · Charge control agent (COPY CHARGE PSYVP2038: manufactured by Clariant Japan Co., Ltd.): 2 The mixture consisting of parts by weight of the composition was subjected to ball milling using zirconia balls having a diameter of 10 mm for 20 hours to obtain dispersion A.

b) Preparation of Charcoal Cal Dispersion B: Calcium carbonate: 40 parts by weight Water: 60 parts by weight of the mixture was pulverized with a ball mill in the same manner as in the preparation of Dispersion A, and charcoal cal dispersion Liquid B was obtained.

c) Preparation of liquid mixture C: 2% serogen aqueous solution: 4.3 g, charcoal cal dispersion B 8.5 g, 20% saline: Degassing the mixture of 50 g with an ultrasonic disperser The mixture was stirred for 10 minutes and then stirred with an emulsifier to obtain a mixed solution C.

d) Production of particles: 35 g of dispersion A, 1 g of divinylbenzene, and polymerization initiator AIBN (azoisobutyronitrile): 0.35 g is weighed and mixed thoroughly, and deaerated by an ultrasonic disperser. I went for a minute. This was put into the mixed solution C and emulsified with an emulsifier. Next, this emulsified liquid was put into a bottle, and the bottle was filled with silicone soot and sufficiently degassed under reduced pressure, and then nitrogen gas was sealed. And it was made to react at 70 degreeC for 10 hours, and particle | grains were produced. After cooling, this was taken out, and calcium carbonate was decomposed with an excessive amount of 3 mol / l hydrochloric acid, followed by filtration. Then, it was washed with sufficient distilled water, and openings were used: 20 μm and 25 μm nylon sieves were used, and 25 μm particles were permeated and 20 μm particles were not permeated. This was dried to produce white particles-1 having a volume average particle diameter of 23 μm.

(Blue particle-1)
In the above (white particle-1), the step of “a) Preparation of dispersion A” is replaced with the following step, and the subsequent step in (white particle-1) is performed using the obtained dispersion A ′. (Blue particle-1) was produced.

a) Preparation of dispersion A ′: Styrene monomer: 87 parts by weight Blue pigment (Pigment Blue 15: 3, SANYO Cyanine Blue KRO: Sanyo Dye Co., Ltd.): 10 parts by weight Charge control agent (BONTRON E- 84: manufactured by Orient Chemical Co., Ltd.) The mixture consisting of 2 parts by weight of the composition was subjected to ball milling using zirconia balls having a diameter of 10 mm for 20 hours to obtain dispersion A ′.

(White particles-2)
In the above (white particle-1), the charge control agent (COPY CHARGE PSYVP2038: manufactured by Clariant Japan Co., Ltd.) was not used in the step of “a) Preparation of Dispersion A”, and styrene was increased by that amount (2 parts by weight). Except that, white particles-2 were produced in the same manner as white particles-1.

(Blue particle-2)
In the above (white particle-1), the charge control agent (COPY CHARGE PSYVP2038: manufactured by Clariant Japan Co., Ltd.) is not used in the step of “a) Preparation of Dispersion A ′”. Except for the above, operations were performed in the same manner as for blue particle-1, and blue particle-2 was produced.

  White particles and blue particles obtained as described above are mixed to prepare mixed particles, which are used by being enclosed in a space between the substrates. At this time, the blending ratio (number basis) of white particles and blue particles is, for example, white particles: blue particles = 2: 1. In the embodiment described above, for example, mixed particles composed of the white particles-1 and the blue particles-1 are used.

  The obtained mixed particles are sealed in a gap between the substrates (display substrate 8 and non-display substrate 18) arranged oppositely as shown in FIG. 1, and a voltage is applied between the transparent electrode 4 and the electrode 14 to obtain a desired electric field. When acting on the particle group between the display substrate 8 and the non-display substrate 18, the particles 22 and 24 move between the display substrate 8 and the non-display substrate 18. By switching the polarity of the applied voltage, each particle 22, 24 moves in a different direction between the display substrate 8 and the non-display substrate 18, and reciprocates between the display substrate 8 and the non-display substrate 18 by repeatedly switching the voltage polarity. To do. In this process, the particles 22 and the particles 24 are charged with different polarities due to the collision between the particles 22 and 24 and between the particles 22 and 24 and the display substrate 8 or the non-display substrate 18.

  In this example, the white particles-1 are charged positively and the blue particles-1 are charged negatively, and move in different directions according to the electric field between the display substrate 8 and the non-display substrate 18, and the electric field is unidirectional. When fixed, the particles 22 and 24 adhere to the display substrate 8 or the non-display substrate 18, respectively, and a uniform high density and high contrast image without image unevenness is displayed.

  The present invention is not limited to the embodiment described above. For example, as the color of the particles, white and blue are given as examples, but various color combinations can be adopted. However, it is preferred that one of the particles is white. Moreover, the size of each member is merely an example, and various sizes can be appropriately selected according to the purpose of use.

  In the image display device of the present invention, the unit of the configuration is a single cell, and a plurality of cells are arranged in a plane (or divided into planes in the gap between opposing substrates). Or a plurality of display elements. It is also possible to configure a large-screen image forming apparatus having a desired resolution by setting the desired number of cells per vertical and horizontal unit length.

  Furthermore, the present invention can also be applied to an image display apparatus having the configuration described in Patent Document 2 described above, that is, the configuration in which the humidity of the gas filling the gap between the substrates is set to a predetermined value or less.

1 is a partially broken schematic side view of an image display device according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 Transparent support 4 Transparent electrode 6 Protective layer 8 Display substrate 10 Image display medium 12 Support body 14 Electrode 16 Protective layer 18 Non-display substrate 20 Voltage generating means 22 Blue particle 24 White particle 26 Spacer 30 Space

Claims (2)

In an image display device in which particles are enclosed in a gap between a pair of substrates arranged opposite to each other, and the particles are moved by an electric field applied between the substrates, an insulating property at a pressure exceeding atmospheric pressure is provided in the gap. An image display device in which gas is sealed. The insulating gas, SF ₆ gas, CO ₂ gas, the image display apparatus according to claim 1, characterized in that consisting of at least one of nitrogen gas and water content 3000ppm or less of the dry air.

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