JP2007025372A - Method for driving panel for information display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for driving a panel for information display by which successful information display is constantly performed without deterioration of display quality level of information such as an image. <P>SOLUTION: In the method for transferring a display medium to display the information such as the image by enclosing the display medium between two substrates at least one of which is transparent and impressing an electric field to the display medium from a pair of opposite electrodes comprised of a line electrode provided to the opposite electrode, drive conditions are varied so that a display state becomes the optimal according to a display state of the panel for display. Specifically, data about temporal change based on display frequencies of the panel for information display is preliminarily collected, the drive conditions are varied according to the display frequencies or a sensor which detects the display state is incorporated into the panel for information display and the drive conditions are varied according to detection results by the sensor. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  According to the present invention, a display medium is sealed between two substrates, at least one of which is transparent, and an electric field is applied to the display medium from a pair of counter electrodes formed by line electrodes provided on the opposing substrates. It is related with the drive method of the information display panel which displays information by moving.

  2. Description of the Related Art Conventionally, information display devices using techniques such as electrophoresis, electrochromic, thermal, and two-color particle rotation have been proposed as information display devices that 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 information 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. In addition, 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 that the stability of repeated information display is lacking. ing. 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 uniformly inject the charge into the conductive particles.

As one method for solving the various problems described above, a cell that is isolated from each other by a partition wall is formed after sealing a display medium between two opposing substrates, at least one of which is transparent. An information display panel that encapsulates a display medium and then applies an electric field to the display medium from a pair of counter electrodes formed by line electrodes provided on opposing substrates and moves the display medium to display information such as an image It has been known.
趙 Kuniaki 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 information display panel described above, when displaying information such as an image, the initial information display panel is tuned to determine an optimum driving condition, and thereafter, driving is performed under the same condition. For this reason, when the characteristics of the information display panel change over time, the driving conditions that were optimal at the initial stage are not optimal, and there is a problem that the display quality of information such as images on the information display panel deteriorates.

  An object of the present invention is to solve the above-mentioned problems and to provide a method for driving an information display panel capable of always displaying good information without deteriorating the display quality of information such as images. is there.

  According to the information display panel driving method of the present invention, an electric field is applied to a display medium from a pair of counter electrodes formed by line electrodes provided on opposing substrates, in which a display medium is sealed between two substrates at least one of which is transparent. In the information display panel drive method for displaying information such as images by moving the display medium, the drive conditions are changed so that the display state is optimized according to the display state of the information display panel It is characterized by making it.

  As a preferred example of the method for driving the information display panel of the present invention, the display medium is configured by combining two types of display media having different charging characteristics and optical reflectance, and the information display panel in advance. The time-dependent data based on the number of display times is collected, the driving condition is changed according to the number of display times based on the time-dependent data, and a sensor that detects the display state is incorporated in the information display panel. The drive conditions are changed according to the results, and the drive conditions to be controlled are erase voltage, erase pulse ON time, erase pulse OFF time, erase pulse application count, write voltage, write pulse ON time, write pulse OFF Time, the number of times the write pulse is applied, or a combination thereof, and the drive condition is comprised of an erase condition and a write condition. The control of the conditions, the constant erase conditions, be carried out by changing only the write condition, there is.

  According to the present invention, the drive condition is changed so as to optimize the display state according to the display state of the information display panel. Based on the data of the change over time, the driving condition is changed according to the number of display times, or a sensor for detecting the display state is incorporated in the information display panel, and the driving condition is set according to the detection result by the sensor. Since it is changed, it is possible to always display good information without degrading the display quality of information such as images.

  First, a basic configuration of an information display panel that is an object of the present invention will be described. In the information display panel which is the subject of the present invention, an electric field is applied to a display medium sealed between two opposing substrates from a pair of opposing electrodes formed by line electrodes provided on the opposing substrates. Along with the applied electric field direction, the charged display medium is attracted by the electric field force or Coulomb force, etc., and the display medium changes the moving direction by the electric field direction change due to the potential switching, thereby displaying information such as an image. Made. Therefore, it is necessary to design the information display panel so that the display medium can move uniformly and maintain stability when rewriting the display repeatedly or when displaying the display information continuously. Here, as the force applied to the particles constituting the display medium, in addition to the force attracted by the Coulomb force between the particles, an electric image force with the electrode and the substrate, an intermolecular force, a liquid cross-linking force, gravity and the like can be considered.

  An example of an information display panel that is an object of the present invention will be described with reference to FIGS. 1 (a) and (b) to FIGS. 3 (a) and 3 (b).

  In the example shown in FIGS. 1A and 1B, at least two kinds of display media 3 (here, white display medium particles 3Wa) having at least one kind of particles and having different optical reflectance and charging characteristics. A white display medium 3W consisting of a group of particles and a black display medium 3B consisting of a particle group of black display medium particles 3Ba) are formed of a pair of line electrodes 5 and 6 provided outside the substrates 1 and 2. Depending on the electric field applied from the counter electrode, the substrate is moved perpendicularly to the substrates 1 and 2 so that the black display medium 3B is visually recognized by the observer and black display is performed, or the white display medium 3W is visually recognized by the observer. White display. In the example shown in FIG. 1B, in addition to the example shown in FIG. 1A, a partition 4 is provided between the substrates 1 and 2, for example, in the form of a lattice to form a cell. In addition, in FIG. 1B, the partition in front is omitted.

  In the example shown in FIGS. 2A and 2B, at least two or more types of display media 3 (here, white display medium particles 3Wa) having different optical reflectance and charging characteristics composed of at least one type of particles. A white display medium 3W made up of a group of particles and a black display medium 3B made up of particles of a black display medium particle 3Ba) are composed of a line electrode 5 provided on the substrate 1 and a line electrode 6 provided on the substrate 2. In accordance with the electric field generated by applying a voltage between the pair of electrodes to be moved, the substrate 1 and 2 are moved vertically and the black display medium 3B is visually recognized by the observer to display black, or The white display medium 3 </ b> W is visually recognized by an observer to perform white display. In the example shown in FIG. 2B, in addition to the example shown in FIG. 2A, for example, a partition 4 is provided between the substrates 1 and 2 to form a cell. Further, in FIG. 2 (b), the front partition is omitted.

  In the example shown in FIGS. 3A and 3B, at least two kinds of display media 3 (here, white display medium particles 3Wa) having different optical reflectivity and charging characteristics composed of at least one kind of particles. A white display medium 3W made up of a group of particles and a black display medium 3B made up of a group of particles 3Ba for black display medium) from a pair of opposing line electrodes 5 and 6 arranged outside the substrates 1 and 2). Depending on the applied electric field, the substrate is moved perpendicularly to the substrates 1 and 2 so that the black display medium 3B is visually recognized by the observer to display black, or the white display medium 3W is visually recognized by the observer. Display is in progress. In the example shown in FIG. 3B, in addition to the example shown in FIG. 3A, for example, a partition 4 is provided between the substrates 1 and 2 to form a cell. Moreover, in FIG.3 (b), the partition in front is abbreviate | omitted. Further, in the information display panel that does not have the line electrodes 5 and 6 integrally as in this example, as shown in FIGS. By providing 6, the present invention can be achieved.

  The above description is similarly applied to the case where the white display medium 3W including the particle group is replaced with the white display medium including the powder fluid and the black display medium 3B including the particle group is replaced with the black display medium including the powder fluid. I can do it.

  FIG. 4 is a diagram for explaining an example of a circuit configuration for carrying out the method for driving the information display panel of the present invention. In the example shown in FIG. 4, 11 is an information display panel configured as described above, 12 is a driver for driving the information display panel 11, 13 is a power supply device capable of supplying a variable voltage, and 14 is for information display. A controller for controlling the driving of the panel 11.

  In the example shown in FIG. 4, the controller 14 supplies a driving condition to be changed to the driver 12 so that the display state of the information display panel 11 is optimal, and supplies the voltage for that to the driver 12 via the power supply device 13. 12 is supplied. The driver 12 generates a column voltage and a row voltage from the supplied voltage according to the supplied driving condition, and the column voltage and the row voltage are used as an example for the one row electrode in the information display panel 11 having a simple matrix configuration. Supplied to the other column electrode. For example, the column voltage and the row voltage generated by the driver 12 are set by controlling driving conditions such as a voltage value to be supplied, a voltage application time, a voltage application frequency, or a combination thereof in accordance with the display frequency. .

  The information display panel driving method of the present invention is used to set driving conditions in the controller 14 in the circuit configuration shown in FIG. Hereinafter, the method for driving the information display panel of the present invention will be described in detail.

  First, the change with time of the display state of the information display panel, which is the premise of the present invention, will be described. FIG. 5 is a diagram for explaining the transition of the change in threshold characteristics in the information display panel that is the subject of the present invention. In the example shown in FIG. 5, an example of white display and black display at N1, N2, N3, and N4 (repetition count: N1 <N2 <N3 <N4) when the display is repeated under the same driving conditions is shown as the optical density. The relationship with the drive voltage is shown. From the example shown in FIG. 5, it can be seen that when the applied voltage is gradually increased and the threshold value of the voltage changing from white display to black display is obtained, the threshold value changes as the number of times of display increases. FIG. 6 is a diagram for explaining the relationship between the change in threshold value and the display quality shown in FIG. Here, it can be seen that when the threshold voltage value is lower than the threshold voltage value when the optimum display state is given, the display quality is deteriorated due to crosstalk as shown in FIG. On the other hand, when the threshold voltage value is higher than the threshold voltage value when the optimum display state is given, it is understood that the display quality is deteriorated due to insufficient driving force as shown in FIG.

  Therefore, it can be seen that if the drive condition is initially set as in the prior art and the display rewriting is continued under the drive condition as it is, the display quality is changed. In the present invention, paying attention to the fact that the threshold value of the driving voltage that changes with time explained in FIGS. 5 and 6 varies by changing various driving conditions, the various driving conditions are changed according to the display state. The above problem was solved by controlling the threshold of the drive voltage so as to always be in the optimum state shown in FIG.

  That is, in the present invention, the driving conditions are changed so that the display state is optimized according to the display state of the information display panel. As a specific control method, it is possible to preliminarily take data of changes over time based on the number of display times of the information display panel and change the driving conditions according to the number of display times based on the data of change over time. As another specific control method, a sensor for detecting the display state can be incorporated in the information display panel, and the drive condition can be changed according to the detection result by the sensor. In any case, the present invention can be suitably implemented. FIG. 7 is a diagram for explaining an example in which the drive condition is changed according to the detection result by the sensor. In FIG. 7, a light emitting unit 21 made of LED and a light receiving unit 22 made of a photosensor are arranged at both ends of the information display panel 11. In this state, a test pattern (solid black, solid white, crosstalk) is periodically displayed on the information display panel 11, the light from the light emitting unit 21 is applied to the panel 11, and the reflected light is received by the light receiving unit 22. The display quality can be maintained by detecting the panel state at that time from the amount of reflected light and performing feedback control.

  Next, drive conditions to be changed in the method for driving the information display panel of the present invention will be described. FIG. 8 is a diagram for explaining each driving condition used in the method for driving the information display panel of the present invention. In the present invention, as shown in FIG. 8, the drive conditions to be controlled are erase voltage, erase pulse ON time, erase pulse OFF time, erase pulse application count, write voltage, write pulse ON time, write pulse OFF. It is preferable to use one of time, the number of times of writing pulse application, or a combination thereof.

  FIG. 9 is a diagram for explaining the relationship between the strengths of the driving forces in the driving conditions described above. The threshold value described above is determined by the balance between the erase strength and the write strength. Here, the strength of erasing and writing means a driving force applied to a display medium composed of particles or powder fluid in the information display panel. By controlling the applied voltage, the ON time, the OFF time, and the number of times of application determined in accordance with the example shown in FIG. 9 or a combination thereof, the threshold value increases when erasing is strong or writing is weak, and vice versa. The value is low. Actual control can be set by considering these relationships.

  Since the threshold value is determined by the balance of both erasing and writing, it becomes difficult to perform optimum tuning if the driving conditions are changed. Therefore, for example, it is desirable to find an optimum condition by keeping the erase condition constant and tuning only the write condition. For example, when tuning an information display panel with a lowered threshold, the erasing condition is fixed, the write voltage (constant), the write ON time (down), the write OFF time (up), and the number of write applications By controlling the driving conditions such as (constant), the threshold value can be increased and display quality can be maintained.

  In the above-described example, the present invention has been described by changing the threshold value. However, in addition to the threshold value, the rising slope and the solid display (the state where no crosstalk is applied) also change. Considering these also, the present invention can be more suitably implemented.

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

  As for the substrate, at least one substrate is the transparent substrate 2 from which the color of the display medium 3 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, polyethylene naphthalate, polyethersulfone, polyethylene, polycarbonate, polyimide, and acrylic, flexible materials such as metal sheets, and glass and quartz. An inorganic sheet having no flexibility is mentioned. 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 spacing uniformity between the substrates, and if it is thicker than 5000 μm, it will be a thin information display panel. Is inconvenient.

  As an electrode forming material of the electrode provided in the information display panel, metals such as aluminum, silver, nickel, copper, and gold, conductive metal oxides such as ITO, indium oxide, conductive tin oxide, and conductive zinc oxide, Examples include conductive polymers such as polyaniline, 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. The method of apply | coating is used. The electrode provided on the viewing side (display surface side) substrate needs to be transparent, but the electrode provided on the back side substrate 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 side substrate are the same as those of the electrode provided on the display surface side substrate described above, but need not be transparent. In this case, the external voltage input may be superimposed with direct current or alternating current.

  The partition 4 provided on the substrate as required is optimally set depending on the type of display medium involved in display, and is not limited in general. However, the width of the partition is 2 to 100 μm, preferably 3 to 50 μm. The height of the partition wall is adjusted to 10 to 500 μm, preferably 10 to 200 μm. As shown in FIG. 10, the cells formed by the partition walls made of these ribs are illustrated in a square shape, a triangular shape, a line shape, a circular shape, and a hexagonal shape as viewed from the substrate plane direction. And a mesh shape. It is better to make the portion corresponding to the cross section of the partition wall visible from the display surface side (the area of the cell frame) as small as possible, and the display becomes clearer.

  Next, the powder fluid used as a display medium in the information display panel that is the subject of the present invention will be described. As for the name of the powder fluid used in the information display panel of the present invention, the present applicant has obtained the right of “Electronic Powder Fluid (registered trademark): Registration No. 4636931”.

  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, in a dispersion system in which a solid or liquid substance is stably suspended as a dispersoid in a gas, and the solid substance is regarded as a dispersoid in the information display panel of the present invention. To do.

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

Next, display medium particles (hereinafter also referred to as particles) constituting the display medium in the information display panel of the present invention will be described. The display medium particles are composed of the display medium particles as they are to form a display medium, or are combined with other particles to form a display medium, or adjusted and configured to become a powder fluid to form a display medium. Or used.
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 chrome yellow, 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 chrome yellow, 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.

As extender pigments, barite powder, barium carbonate, clay, silica, white carbon,
There are 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 of the present invention preferably have an average particle diameter d (0.5) in the range of 0.1 to 20 μm and are uniform and uniform. 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 the display medium can be moved uniformly.

  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. Even if the particle size distribution Span is reduced, particles with different charging characteristics move in opposite directions, so that the particle size is close to each other and each particle can be easily moved in the opposite direction by the equivalent amount. This is within this range.

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 display medium particles naturally depends on the measurement conditions, but the charge amount of the display medium particles in the information display panel is almost the same as the initial charge amount, the contact with the partition walls, the contact with the substrate, and the elapsed time. It was found that depending on the charge decay, the saturation value of the charging behavior of the particles for the display medium is a dominant factor.

  As a result of intensive studies, the inventors of the present invention have been able to evaluate the range of proper charging characteristics of display medium particles by measuring the charge amount of display medium particles using the same carrier particles in the blow-off method. I found it.

Furthermore, in the dry information display panel, it is important to manage the gas in the voids surrounding the display medium, 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.
1A, 1B, 3A, and 3B, the gaps are defined by the electrodes 5 and 6 (the electrodes are placed on the inside of the substrate). Gas portion in contact with the so-called display medium, excluding the occupied portion of the display medium 3 (particle group or powdered fluid), the occupied portion of the partition wall 4 (when the partition wall is provided), and the seal portion of the information display panel. Shall be pointed to.
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 in an information display panel so that the humidity is maintained, for example, filling a display medium, assembling an information display panel in a predetermined humidity environment, It is important to apply a sealing material and a sealing method that prevent moisture from entering from the outside.

The distance between the substrates in the information display panel of the present invention is not limited as long as the 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.
In the case of a dry information display panel, the volume occupancy of the display medium in the space between the opposing substrates is preferably 5 to 70%, more preferably 5 to 60%. When it exceeds 70%, the movement of the display medium is hindered, and when it is less than 5%, the contrast tends to be unclear.

  Information display panels subject to the driving method of the present invention include display units of mobile devices such as notebook computers, PDAs, mobile phones, and handy terminals, electronic papers such as electronic books and electronic newspapers, signboards, posters, and blackboards. For bulletin boards, calculators, home appliances, automobile supplies, etc., card displays such as point cards, IC cards, electronic advertisements, electronic POPs, electronic shelf labels, electronic price tags, electronic musical scores, RF-ID device displays, etc. Preferably used.

(A), (b) is a figure which shows an example of the information display panel used as the object of this invention, respectively. (A), (b) is a figure which shows the other example of the information display panel used as the object of this invention, respectively. (A), (b) is a figure which shows the further another example of the information display panel used as the object of this invention, respectively. It is a figure for demonstrating an example of the circuit structure which implements the drive method of the information display panel of this invention. It is a figure for demonstrating transition of the change of the threshold value characteristic in the information display panel used as the object of this invention. It is a figure for demonstrating the relationship between the change of the threshold value shown in FIG. 5, and display quality. It is a figure for demonstrating an example at the time of changing a drive condition according to the detection result by a sensor. It is a figure for demonstrating each drive condition used with the drive method of the information display panel of this invention. It is a figure for demonstrating the relationship of the strength of the driving force in the driving condition shown in FIG. It is a figure which shows an example of the shape of the partition in the information display panel used as the object of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Substrate 3 Display medium 3W White display medium 3Wa White display medium particle 3B Black display medium 3Ba Black display medium particle 4 Partition 5, 6 Electrode 11 Information display panel 12 Driver 13 Power supply device 14 Controller 21 Light emitting part 22 Light receiving Part

Claims (6)

  A display medium is sealed between two substrates, at least one of which is transparent, and the display medium is moved by applying an electric field to the display medium from a pair of counter electrodes composed of line electrodes provided on the opposing substrates. In the method for driving an information display panel for displaying information such as an image, the driving condition is changed so that the display state is optimized in accordance with the display state of the information display panel. Method.   The method for driving an information display panel according to claim 1, wherein the display medium is configured by combining two types of display media having different charging characteristics and optical reflectance.   3. The information display according to claim 1, wherein data of a change with time based on the number of times of display of the information display panel is taken in advance, and the driving condition is changed according to the number of times of display based on the data of the change with time. Panel drive method.   The method for driving an information display panel according to claim 1 or 2, wherein a sensor for detecting the display state is incorporated in the information display panel, and the drive condition is changed according to the detection result of the sensor.   The drive condition to be controlled is one of erase voltage, erase pulse ON time, erase pulse OFF time, erase pulse application count, write voltage, write pulse ON time, write pulse OFF time, write pulse application count, or The method for driving an information display panel according to claim 1, which is a combination thereof. 6. The driving condition includes an erasing condition and a writing condition, and the driving condition is controlled by making the erasing condition constant and changing only the writing condition. A method for driving the described information display panel.

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