JP4657639B2 - Image forming method for image display panel - Google Patents

Description

  According to the present invention, an image display medium is sealed between opposing substrates, at least one of which is transparent, a voltage is applied to an electrode provided on the substrate side, an electric field is applied to the image display medium, and the image display medium is moved to move the image. The present invention relates to an image forming method for an image display panel that displays the image.

  2. Description of the Related Art Conventionally, image display devices using techniques such as an electrophoresis method, an electrochromic method, a thermal method, and a two-color particle rotation method have been proposed as image display devices that can replace liquid crystal (LCD).

  Compared to LCDs, these conventional technologies have advantages such as a wide viewing angle close to that of ordinary printed materials, low power consumption, and a memory function. It is considered as a technology that can be used for mobile phones, and is expected to expand to image display for mobile terminals, electronic paper, and the like. Particularly recently, an electrophoretic method in which a dispersion liquid composed of dispersed particles and a colored solution is encapsulated and disposed between opposing substrates has been proposed and is expected.

  However, the electrophoresis method has a problem that the response speed becomes slow due to the viscous resistance of the liquid because the particles migrate in the liquid. Furthermore, since particles with high specific gravity such as titanium oxide are dispersed in a solution with low specific gravity, it is easy to settle, and it is difficult to maintain the stability of the dispersed state, and there is a problem of lack of image repetition stability. . Even when microencapsulation is performed, the cell size is set to the microcapsule level, and the above-described drawbacks are hardly made to appear, and the essential problems are not solved at all.

  On the other hand, a method in which conductive particles and a charge transport layer are incorporated into a part of a substrate without using a solution is proposed instead of an electrophoresis method using behavior in a solution (see, for example, Non-Patent Document 1). ). However, the structure is complicated because the charge transport layer and further the charge generation layer are arranged, and it is difficult to inject the charges into the conductive particles.

As one method for solving the various problems described above, a cell isolated from each other by a partition is formed between two opposing substrates, at least one of which is transparent, and an image display medium is sealed in the cell. 2. Description of the Related Art An image display panel that displays an image by applying an electric field to an image display medium and moving the image display medium is known.
趙 Kuniori and three others, “New Toner Display Device (I)”, July 21, 1999, Annual Meeting of the Imaging Society of Japan (83 times in total) “Japan Hardcopy'99” Proceedings, p.249-252

  In the above-described conventional image display panel, a display pattern electrode formed in an image display portion on the substrate and a lead electrode serving as a lead wiring from the display pattern electrode are provided on the substrate. When a glass substrate is used, it is difficult to wire the lead electrode from the display pattern electrode to the back side of the substrate using a through hole like a copper-clad laminate. Since the same voltage as that of the display pattern electrode is applied to the extraction electrode, the image display medium is inverted also in the portion of the extraction electrode other than the display pattern portion, resulting in a significant deterioration in display quality.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming method for an image display panel that solves the above-described problems, eliminates image disturbance caused by an extraction electrode, and improves display quality. is there.

Image forming how the display panel of the present invention provides an electric field to at least one of sealed image display medium between the substrates of transparent counter, the image display medium by applying a voltage to electrodes provided on the substrate side Then, in the image forming method of the image display panel for displaying the image by moving the image display medium, the electrode on one substrate side is used as a display pattern electrode, a lead electrode serving as a lead wiring from the display pattern electrode, and A display pattern electrode corresponding to the display pattern electrode on the one substrate side, the electrode on the other substrate side comprising a background electrode provided on a portion other than the display pattern electrode and a portion other than the lead electrode, These display pattern electrodes are integrally connected to the connection electrodes and the portions other than the display pattern electrodes and correspond to at least one substrate-side extraction electrode. Min was composed of the independent electrodes configured in a portion including, after the normal image forming process, by applying a sufficient voltage to the display is rewritten to the independent electrodes, image by image disturbance of lead electrode portions It is characterized by reducing the deterioration of quality.

  Further, as a preferred example of the image forming method of the image display panel of the present invention, the electrode on the other substrate side is replaced with a display pattern electrode corresponding to the display pattern electrode on the one substrate side, and a display pattern electrode. A lead-out electrode to be a lead-out line, and a portion other than the display pattern electrode, which is an independent electrode configured in a portion including a portion corresponding to the lead-out electrode on at least one substrate side; and The image display medium may be a particle group or a powder fluid.

  In the image forming method of the image display panel of the present invention, the electrodes are divided in advance into the image display pattern electrode part (segment electrode part) and the lead electrode and the other (background part including the lead line of the counter substrate). In an image display panel prepared so that a separate voltage can be applied, by applying a voltage below a threshold value that does not change the display to the independent electrode during the image forming process (first invention), or By applying a voltage sufficient for rewriting the display to the independent electrode after the normal image forming process (second invention), it is possible to reduce the image quality degradation due to the image disturbance of the extraction electrode portion.

  First, a basic configuration of an image display panel that is an object of the present invention will be described. In the image display panel used in the present invention, an electric field is applied to two types of image display media (particle group or powder fluid) sealed between two opposing substrates and having different charging characteristics. Along with the applied electric field direction, the image display medium charged at a low potential toward the high potential side is attracted by the force of the electric field or the Coulomb force, and is charged at a high potential toward the low potential side. The image display medium is attracted by an electric field force, a Coulomb force, or the like, and the image display medium is reciprocated by a change in the electric field direction due to the potential switching, thereby displaying an image. Therefore, it is necessary to design the image display panel so that the image display medium moves uniformly and can maintain stability during repetition or storage. Here, the force applied to the particles or powder fluid used as the image display medium is not only the force attracted by the Coulomb force between the particles or powder fluid, but also the image power, intermolecular force, liquid crosslinking force with the electrode or substrate. , Gravity and so on.

An example of an image display panel which is an object of the present invention will be described based on FIGS. 1 (a) and (b) to FIGS. 2 (a) and 2 (b).
In the example shown in FIGS. 1 (a) and 1 (b), two or more kinds of image display media 3 having different colors (here, white particles 3W and black particles 3B) are provided outside the substrates 1 and 2. Depending on the electric field applied from (not shown), the substrate is moved vertically with respect to the substrates 1 and 2 and the black particles 3B are visually recognized by the observer to display black, or the white particles 3W are visually recognized by the observer. White display. In the example shown in FIG. 1B, in addition to the example shown in FIG. 1A, partition walls 4 are provided, for example, in a lattice shape between the substrates 1 and 2 to define display cells.
In the example shown in FIGS. 2A and 2B, two or more kinds of image display media 3 having different colors (here, white particles 3W and black particles 3B are shown) are provided on the substrate 1 and the substrate 2. In accordance with the electric field generated by applying a voltage between the electrode 6 and the electrode 6 provided on the substrate, the substrate is moved perpendicularly to the substrates 1 and 2, and the black particles 3B are visually recognized by the observer, or black display is performed. The white particles 3W are visually recognized by an observer to display white. In the example shown in FIG. 2B, in addition to the example shown in FIG. 2A, partition walls 4 are provided, for example, in a lattice form between the substrates 1 and 2 to define display cells.
The above description can be similarly applied to the case where the white particles 3W are replaced with the white powder fluid and the black particles 3B are replaced with the black powder fluid.

  The image forming method of the image display panel according to the present invention is characterized in that, when an image is displayed on the image display panel having the above-described configuration, the electrode on one substrate side is drawn out from the display pattern electrode and the display pattern electrode. Consists of a lead electrode serving as wiring and a background electrode provided in a portion other than the display pattern electrode and a portion other than the lead electrode, and corresponds to at least the lead electrode on the one substrate side on the other substrate side An independent electrode is formed at a position, and a voltage below a threshold value that does not change the display is applied to the independent electrode during the image forming process (first invention), or after the normal image forming process, By applying a voltage sufficient to rewrite the display on the electrode (second invention), it is possible to reduce degradation of image quality due to image disturbance in the extraction electrode portion. That. Hereinafter, this feature will be described.

  FIGS. 3A and 3B are diagrams for explaining electrodes used in the image forming method of the image display panel of the present invention. In the example shown in FIGS. 3A and 3B, segment electrodes (so-called 7 segments) for displaying the numeral 8 are shown.

  As shown in FIG. 3A, the electrode 5 on one substrate 1 (for example, glass substrate) side is composed of 7-segment display pattern electrodes 11-1 to 11-7 and display pattern electrodes 11-1 to 11-1. The segment electrodes SEG1 to SEG7 for image display are constituted by the lead electrodes 12-1 to 12-7 serving as lead wirings from 11-7. Further, a common electrode (background electrode) COM3 as a background is provided in a portion other than the display pattern electrodes 11-1 to 11-7 and a portion other than the lead electrodes 12-1 to 12-7. An insulation interval 13 is provided between the segment electrodes SEG1 to SEG7 and the common electrode COM3.

  The electrode 6 on the other substrate 2 (for example, glass substrate) side is, as shown in FIG. 3B, the display pattern electrode 21-corresponding to the display pattern electrodes 11-1 to 11-7 constituting the electrode 5. The common electrode COM1 is composed of 1 to 21-7 and the connection electrode 22 in which the display pattern electrodes 21-1 to 21-7 are integrally continuous. Further, a common electrode (independent electrode) COM2 is provided in a portion other than the display pattern electrodes 21-1 to 21-7 and the connection electrode 22, that is, a portion other than the common electrode COM1. An insulation interval 23 is provided between the common electrode COM1 and the common electrode COM2.

  A case where the number “5” is actually displayed using the image display panel using the electrodes having the structure shown in FIGS. 3A and 3B will be described. As the image display medium 3, an image display panel using the white particle group 3W and the black particle group 3B having inversion characteristics as shown in FIG. 4 was used in any of the following descriptions. Here, the writing voltage (same as the threshold voltage) of the white particle group 3W is −V, and the writing voltage (same as the threshold voltage) of the black particle group 3B is + V.

  FIG. 5 is a diagram for explaining an example of a conventional image forming method in the image display panel. In the conventional image forming method shown in FIG. 5, one electrode 5 has the same configuration as that shown in FIG. 3A, and the other electrode 6 is a common electrode COM4 that covers the whole. In this conventional example, in order to display the number “5” from a white state where nothing is displayed, a write voltage + V is applied to SEG1, SEG3, SEG4, SEG6, SEG7, and SEG2, SEG5, COM3 are displayed. , 0 is applied to COM4. In this case, the display pattern electrodes 11-1, 11-3, 11-4, 11-6, and 11-7 of SEG1, SEG3, SEG4, SEG6, and SEG7 are not only reversed to display black, Even the lead electrodes 12-1, 12-3, 12-4, 12-6, and 12-7 are reversed to display black. As a result, the display quality of the image is remarkably deteriorated.

  FIG. 6 is a view for explaining an example in the first invention of the image forming method of the present invention in the image display panel. In the first invention of the present invention shown in FIG. 6, in order to display the numeral “5” from a white state where nothing is displayed, first, the electrode 5 on one substrate 1 is not subjected to the conventional technique. As in the example, the write voltage + V is applied to SEG1, SEG3, SEG4, SEG6, and SEG7. At the same time, for the electrode 6 on the other substrate 2 side, a voltage 0 is applied to COM1, and a common electrode COM2 for applying a voltage to portions other than the display pattern electrodes 21-1 to 21-7 is applied to, for example, Then, a voltage + V / 2 that is 1/2 of the write voltage + V is applied.

  In this example, the portion of the common electrode COM2 only takes a voltage of ± V / 2, and is a value equal to or lower than the threshold voltage V from the inversion characteristics of FIG. 4, so that the extraction electrodes 12 constituting the segment electrodes SEG1 to SEG7 The display of -1 to 12-7 is not reversed and white display continues. As a result, the display quality of the image is not deteriorated. Note that the portion where the lead electrodes 12-1 to 12-7 of the electrode 5 and the connection electrode 22 of the electrode 6 cross is inverted to black because a threshold voltage + V is applied, but is a small region compared to the whole. Therefore, there is no particular problem in terms of image quality.

  FIG. 7 is a view for explaining an example in the second invention of the image forming method of the present invention in the image display panel. In the second invention of the present invention shown in FIG. 7, in order to display the numeral “5” from a white state where nothing is displayed, first, an image is obtained by a normal method similar to the conventional example shown in FIG. Once formed. At that time, as shown in FIG. 5, the portions corresponding to the extraction electrodes 12-1, 12-3, 12-4, 12-6, and 12-7 are in a state of being inverted to black.

  In this example, a voltage 0 is then applied to SEG1 to SEG7 and COM3 for the electrode 5 on one substrate 1 side, and a voltage 0 is applied to COM1 for the electrode 6 on the other substrate 2 side. At the same time, a write voltage + V is applied to COM2. As a result, the write voltage −V is applied to the portions corresponding to the extraction electrodes 12-1, 12-3, 12-4, 12-6, and 12-7. As a result, the portions corresponding to the extraction electrodes 12-1, 12-3, 12-4, 12-6, and 12-7, which are black, reinvert to white and become white with the same color as the surroundings. In this example as well, as in the example shown in FIG. 6, black remains at the portion where the lines cross, but this is not a problem in terms of image quality because it is a smaller area than the whole.

  When the first invention of the present invention shown in FIG. 6 is compared with the second invention of the present invention shown in FIG. 7, when an image display panel having a non-steep threshold characteristic as shown in FIG. In the first invention of the present invention, when ± V / 2 is applied, the portion becomes gray instead of white, whereas in the second invention of the present invention shown in FIG. Kept. From the above, when using the image display medium 3 whose display reversal applied voltage threshold is not steep, in the first invention shown in FIG. 6, there is a possibility that a slight display reversal occurs and the display quality deteriorates. Even in this case, the second invention of the present invention shown in FIG. On the other hand, the second invention of the present invention shown in FIG. 7 has more image forming steps than the first invention of the present invention shown in FIG. Therefore, it is preferable to select and use the first invention and the second invention according to the demands of image quality and process.

  Hereinafter, each member which comprises the image display panel used as the object of this invention is demonstrated.

  As for the substrate, at least one of the substrates is a transparent substrate 2 on which the color of the image display medium can be confirmed from the outside of the panel, and a material having high visible light transmittance and good heat resistance is preferable. The substrate 1 may be transparent or opaque. Examples of substrate materials include polymer sheets such as polyethylene terephthalate, polyethersulfone, polyethylene, polycarbonate, polyimide, and acrylic, flexible materials such as metal sheets, and flexible materials such as glass and quartz. There are no inorganic sheets. The thickness of the substrate is preferably from 2 to 5000 μm, more preferably from 5 to 2000 μm. If it is too thin, it will be difficult to maintain the strength and the uniformity of the distance between the substrates. There is an inconvenience.

  Electrode forming materials for electrodes provided on the substrate side include metals such as aluminum, silver, nickel, copper, and gold, conductive metal oxides such as ITO, indium oxide, conductive tin oxide, and conductive zinc oxide, polyaniline, Examples thereof include conductive polymers such as polypyrrole and polythiophene, which are appropriately selected and used. As a method for forming an electrode, a method of forming the above-described materials into a thin film by sputtering, vacuum deposition, CVD (chemical vapor deposition), coating, or the like, or mixing a conductive agent with a solvent or a synthetic resin binder. A method of applying is used. The electrode provided on the viewing substrate side needs to be transparent, but the electrode provided on the back substrate side does not need to be transparent. In any case, the above-mentioned material that is conductive and capable of pattern formation can be suitably used. Note that the electrode thickness is not particularly limited as long as the conductivity can be secured and the light transmittance is not hindered, and is preferably 3 to 1000 nm, preferably 5 to 400 nm. The material and thickness of the electrode provided on the back substrate side are the same as those of the electrode provided on the viewing substrate side described above, but need not be transparent. In this case, the external voltage input may be superimposed with direct current or alternating current.

  The shape of the partition 4 provided as needed is optimally set according to the type of image display medium involved in the display, and is not limited in general. However, the width of the partition is 2 to 100 μm, preferably 3 to 50 μm. Is adjusted to 10 to 500 μm, preferably 10 to 200 μm. In forming the partition walls, a both-rib method in which ribs are formed on each of the opposing substrates and then bonded, and a one-rib method in which ribs are formed only on one substrate are conceivable. In the present invention, any method is preferably used.

  As shown in FIG. 9, the display cells formed by the partition walls made up of these ribs are exemplified by a square shape, a triangular shape, a line shape, a circular shape, and a hexagonal shape as viewed from the substrate plane direction. The shape and the mesh shape are exemplified. It is better to make the portion corresponding to the cross section of the partition wall visible from the display side (the area of the frame portion of the display cell) as small as possible, and the sharpness of the image display increases. Examples of the method for forming the partition include a mold transfer method, a screen printing method, a sand blast method, a photolithography method, and an additive method. Among these, a photolithography method using a resist film and a mold transfer method are preferably used. In any method, the present invention can be suitably used.

  Next, the powder fluid as an image display medium used in the image forming method of the present invention will be described. As for the name of the powder fluid as the image display medium of the present invention, the present applicant has obtained the right of “Electronic Powder Fluid (registered trademark)”.

  The “powder fluid” in the present invention is a substance in an intermediate state of both fluid and particle characteristics that exhibits fluidity by itself without borrowing the force of gas or liquid. For example, liquid crystal is defined as an intermediate phase between a liquid and a solid, and has fluidity that is a characteristic of liquid and anisotropy (optical properties) that is a characteristic of solid (Heibonsha: Encyclopedia) . On the other hand, the definition of particle is an object with a finite mass even if it is negligible, and is said to be affected by gravity (Maruzen: Physics Encyclopedia). Here, even in the case of particles, there are special states of gas-solid fluidized bed and liquid-solid fluids. When gas is flowed from the bottom plate to the particles, upward force is applied to the particles according to the velocity of the gas. Is a gas-solid fluidized bed that is in a state where it can easily flow when it balances with gravity, and it is also called a liquid-solid fluidized state that is fluidized by a fluid (ordinary) Company: Encyclopedia). As described above, the gas-solid fluidized bed body and the liquid-solid fluid are in a state of using a gas or liquid flow. In the present invention, it has been found that a substance in a state of fluidity can be produced specifically without borrowing the force of such gas and liquid, and this is defined as powder fluid.

  That is, the pulverulent fluid in the present invention is in an intermediate state having both the characteristics of particles and liquid, as in the definition of liquid crystal (liquid and solid intermediate phase), and is the characteristic of the above-mentioned particles. It is a substance that is extremely unaffected and exhibits a unique state with high fluidity. Such a substance can be obtained in an aerosol state, that is, a dispersion system in which a solid or liquid substance is stably suspended as a dispersoid in a gas, and the solid substance is used as a dispersoid in the image display device of the present invention. Is.

The image display panel which is the object of the present invention exhibits high fluidity in an aerosol state in which solid particles are stably suspended as a dispersoid as an image display medium, for example, as an image display medium between opposing substrates, at least one of which is transparent. The powder fluid is sealed, and such powder fluid can be easily and stably moved by Coulomb force or the like by applying a low voltage.
As described above, for example, the powder fluid used in the present invention is a substance in an intermediate state between fluid and particles, which exhibits fluidity by itself without borrowing the force of gas or liquid. This powder fluid can be in an aerosol state in particular, and in the image display device of the present invention, a solid substance is used in a state of relatively stably floating as a dispersoid in the gas.

  Next, particles as an image display medium used in the image forming method of the present invention will be described. The particles can contain a charge control agent, a colorant, an inorganic additive, and the like, if necessary, in the resin as the main component, as in the conventional case. Examples of resins, charge control agents, colorants, and other additives will be given below.

  Examples of the resin include urethane resin, urea resin, acrylic resin, polyester resin, acrylic urethane resin, acrylic urethane silicone resin, acrylic urethane fluororesin, acrylic fluororesin, silicone resin, acrylic silicone resin, epoxy resin, polystyrene resin, styrene Acrylic resin, polyolefin resin, butyral resin, vinylidene chloride resin, melamine resin, phenol resin, fluororesin, polycarbonate resin, polysulfone resin, polyether resin, polyamide resin and the like can be mentioned, and two or more kinds can be mixed. In particular, acrylic urethane resin, acrylic silicone resin, acrylic fluororesin, acrylic urethane silicone resin, acrylic urethane fluororesin, fluororesin, and silicone resin are suitable from the viewpoint of controlling the adhesive force with the substrate.

  The charge control agent is not particularly limited. Examples of the negative charge control agent include salicylic acid metal complexes, metal-containing azo dyes, metal-containing oil-soluble dyes (including metal ions and metal atoms), and quaternary ammonium salt systems. Examples thereof include compounds, calixarene compounds, boron-containing compounds (benzyl acid boron complexes), and nitroimidazole derivatives. Examples of the positive charge control agent include nigrosine dyes, triphenylmethane compounds, quaternary ammonium salt compounds, polyamine resins, imidazole derivatives, and the like. In addition, metal oxides such as ultrafine silica, ultrafine titanium oxide, ultrafine alumina, nitrogen-containing cyclic compounds such as pyridine and derivatives and salts thereof, various organic pigments, resins containing fluorine, chlorine, nitrogen, etc. are also charged. It can also be used as a control agent.

  As the colorant, various organic or inorganic pigments and dyes as exemplified below can be used.

Examples of the black colorant include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon and the like.
Examples of blue colorants include C.I. I. Pigment blue 15: 3, C.I. I. Pigment Blue 15, Bituminous Blue, Cobalt Blue, Alkaline Blue Lake, Victoria Blue Lake, Phthalocyanine Blue, Metal-free Phthalocyanine Blue, Phthalocyanine Blue Partial Chlorides, Fast Sky Blue, Indanthrene Blue BC and the like.
Examples of red colorants include bengara, cadmium red, red lead, mercury sulfide, cadmium, permanent red 4R, risor red, pyrazolone red, watching red, calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, Alizarin Lake, Brilliant Carmine 3B, C.I. I. Pigment Red 2 etc.

Yellow colorants include yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral first yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa Yellow G, Hansa Yellow 10G, Benzidine Yellow G, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake, C.I. I. Pigment Yellow 12 etc.
Examples of green colorants include chrome green, chromium oxide, pigment green B, C.I. I. Pigment Green 7, Malachite Green Lake, Final Yellow Green G, etc.
Examples of the orange colorant include red yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK, C.I. I. Pigment Orange 31 etc.
Examples of purple colorants include manganese purple, first violet B, and methyl violet lake.
Examples of white colorants include zinc white, titanium oxide, antimony white, and zinc sulfide.

  Examples of extender pigments include barite powder, barium carbonate, clay, silica, white carbon, talc, and alumina white. Examples of various dyes such as basic, acidic, disperse, and direct dyes include nigrosine, methylene blue, rose bengal, quinoline yellow, and ultramarine blue.

Examples of inorganic additives include titanium oxide, zinc white, zinc sulfide, antimony oxide, calcium carbonate, lead white, talc, silica, calcium silicate, alumina white, cadmium yellow, cadmium red, cadmium orange, titanium yellow, Examples include bitumen, ultramarine blue, cobalt blue, cobalt green, cobalt violet, iron oxide, carbon black, manganese ferrite black, cobalt ferrite black, copper powder, and aluminum powder.
These pigments and inorganic additives can be used alone or in combination. Of these, carbon black is particularly preferable as the black pigment, and titanium oxide is preferable as the white pigment.

  Further, the particles as the image display medium of the present invention preferably have a uniform average particle diameter d (0.5) in the range of 0.1 to 50 μm. If the average particle diameter d (0.5) is larger than this range, the display is not clear, and if it is smaller than this range, the cohesive force between the particles becomes too large, which hinders the movement of the particles.

Furthermore, in the present invention, regarding the particle size distribution of each particle, the particle size distribution Span represented by the following formula is less than 5, preferably less than 3.
Span = (d (0.9) −d (0.1)) / d (0.5)
(However, d (0.5) is a numerical value expressing the particle diameter in μm that 50% of the particles are larger than this and 50% is smaller than this, and d (0.1) is a particle in which the ratio of the smaller particles is 10%. (Numerical value expressed in μm, and d (0.9) is a numerical value expressed in μm for a particle diameter of 90% or less.)
By keeping Span within a range of 5 or less, the size of each particle is uniform, and uniform particle movement becomes possible.

  Furthermore, regarding the correlation between the particles, the ratio of d (0.5) of the particles having the minimum diameter to d (0.5) of the particles having the maximum diameter among the used particles is set to 50 or less, preferably 10 or less. It is essential.

The particle size distribution and the particle size can be obtained from a laser diffraction / scattering method or the like. When laser light is irradiated onto particles to be measured, a light intensity distribution pattern of diffracted / scattered light is spatially generated, and this light intensity pattern has a corresponding relationship with the particle diameter, so that the particle diameter and particle diameter distribution can be measured. .
Here, the particle size and particle size distribution in the present invention are obtained from a volume-based distribution. Specifically, using a Mastersizer2000 (Malvern Instruments Ltd.) measuring instrument, particles are introduced into a nitrogen stream, and the attached analysis software (software based on volume-based distribution using Mie theory) The diameter and particle size distribution can be measured.

  The charge amount of the image display medium naturally depends on the measurement conditions, but the charge amount of the image display medium in the image display panel is almost the initial charge amount, the contact with the partition wall, the contact with the substrate, and the charge decay with the elapsed time. In particular, it was found that the saturation value of the charging behavior of the image display medium is the dominant factor.

Furthermore, in the present invention, when a particle group or a powder fluid is used as the image display medium, it is important to manage the gas in the voids surrounding the image display medium between the substrates, which contributes to improved display stability. Specifically, it is important that the relative humidity at 25 ° C. is 60% RH or less, preferably 50% RH or less, more preferably 35% RH or less with respect to the humidity of the gas in the gap.
This void portion refers to the electrodes 5 and 6 and the image display medium (particles) from the portion sandwiched between the opposing substrate 1 and substrate 2 in FIGS. 1 (a), 1 (b) to 2 (a), (b). It refers to the gas portion in contact with the so-called image display medium, excluding the group or powdered fluid 3) occupied portion, the partition 4 occupied portion (if present), and the device seal portion.
The gas in the gap is not limited as long as it is in the humidity region described above, but dry air, dry nitrogen, dry argon, dry helium, dry carbon dioxide, dry methane, and the like are preferable. This gas needs to be sealed between the panel substrates so that the humidity is maintained. For example, filling of the image display medium, assembly of the substrate, etc. are performed in a predetermined humidity environment. It is important to apply a sealing material and a sealing method that prevent moisture from entering.

The distance between the substrates in the image display panel that is the object of the image forming method of the present invention is not limited as long as the image display medium can be moved and the contrast can be maintained, but is usually adjusted to 10 to 500 μm, preferably 10 to 200 μm. Is done.
The volume occupation ratio of the image display medium in the space between the opposing substrates is preferably 5 to 70%, more preferably 5 to 60%. If it exceeds 70%, the movement of the image display medium is hindered. If it is less than 5%, the contrast tends to be unclear.

  Image display panels subject to the image forming method of the present invention include display units of mobile devices such as notebook computers, PDAs, mobile phones, handy terminals, electronic papers such as electronic books and electronic newspapers, signboards, posters, blackboards, etc. It is suitably used for display boards for electronic bulletin boards, calculators, home appliances, automobile supplies, card display parts such as point cards and IC cards, electronic advertisements, electronic POPs, electronic price tags, electronic musical scores, and display parts for RF-ID devices. It is done.

(A), (b) is a figure which shows an example of the panel for image display used as the object of this invention, respectively. (A), (b) is a figure which shows the other example of the panel for image displays used as the object of this invention, respectively. (A), (b) is a figure for demonstrating the electrode used with the image formation method of the image display panel of this invention, respectively. It is a graph for demonstrating the inversion characteristic of the image display panel used as the object of this invention. It is a figure for demonstrating an example of the conventional image forming method in an image display panel. It is a figure for demonstrating an example in 1st invention of the image formation method of this invention in an image display panel. It is a figure for demonstrating an example in 2nd invention of the image formation method of this invention in an image display panel. It is a graph for demonstrating the inversion characteristic of the image display panel whose threshold characteristic is not steep. It is a figure which shows an example of the shape of the partition in the image display panel used as the object of this invention.

Explanation of symbols

1, 2 Substrate 3 Image display medium (particle or powder fluid)
3W white particles (white powder fluid)
3B Black particles (black powder fluid)
4 Partitions 5 and 6 Electrodes 11-1 to 11-7, 21-1 to 21-7 Display pattern electrodes 12-1 to 12-7 Lead electrodes 13, 23 Insulation intervals 22 Connection electrodes SEG1 to SEG7 Segment electrodes COM1 to CON7 Common electrode

Claims (2)

An image in which an image display medium is sealed between opposing substrates, at least one of which is transparent, an image is displayed by moving the image display medium by applying a voltage to an electrode provided on the substrate side and applying an electric field to the image display medium. In an image forming method for a display panel, one substrate side electrode is a display pattern electrode, a lead electrode serving as a lead wiring from the display pattern electrode, and a portion other than the display pattern electrode and a portion other than the lead electrode A display electrode corresponding to the display pattern electrode on the one substrate side, a connection electrode integrally connecting these display pattern electrodes, and And an independent electrode formed in a portion other than the display pattern electrode and including a portion corresponding to the lead-out electrode on at least one substrate side. And, after the normal image forming process, by applying a sufficient voltage to replace display on the independent electrode wrote, image display, characterized in that to reduce the image quality degradation due to image disturbance of lead electrode portions Panel image forming method. The image forming method for an image display panel according to claim 1, wherein the image display medium is a particle group or a powder fluid.

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