JP4529351B2 - Image display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reflective image display device, and more particularly to an image display device using an image display medium that can be rewritten repeatedly by driving colored particles by an electric field.
[0002]
[Prior art]
In order to display a color image in a conventional image display device using colored particles, a method of arranging a color filter on the display substrate side has been common. However, this method has a problem that the whiteness and the resolution of the monochrome image are lowered. Therefore, the present inventors have proposed a method of performing color display without impairing the monochrome display image quality by coloring the back substrate surface and performing color display with the back substrate in addition to color display with colored particles (for example, patents). Reference 1).
[0003]
In this method, in addition to displaying the color of the colored particles by attaching the conventional colored particles to the display substrate, the colored particles are moved and assembled in the horizontal direction with respect to the substrate surface to retract the colored particles at a desired site, and are transparent. The color of the back substrate surface is displayed through a display substrate.
[0004]
[Patent Document 1]
JP 2002-169191 A
[0005]
[Problems to be solved by the invention]
However, in the above prior art, only the binary display of displaying the color of the colored particles or the color of the back substrate can be performed, and the display density cannot be changed. For this reason, for example, when white particles and black particles are used as the particles, and a cell whose back substrate is colored R (red), G (green), and B (blue) is one pixel, the maximum is one pixel. Only eight colors (white, black, red, green, blue, cyan, magenta, yellow) can be displayed, and the color display performance is not sufficient.
[0006]
In order to display more colors, the number of cells per pixel may be increased. However, the resolution is lowered, the roughness of the image is conspicuous, and the display quality is deteriorated.
[0007]
The present invention has been made in view of the above problems, and an object of the present invention is to provide an image display device capable of displaying more colors without reducing the resolution.
[0008]
[Means for Solving the Problems]
  In order to solve the above-mentioned problem, the invention described in claim 1 includes a display substrate having at least translucency, a back substrate facing the display substrate, a colored portion provided on the back substrate side, and the display substrate. A charged particle group that is movably enclosed between the substrates by an electric field formed by a voltage applied between the back substrate and the substrate and has a color different from the color of the colored portion, and a display side provided on the display substrate side An image display medium comprising: an electrode; and a back side electrode composed of an inner electrode and an outer electrode provided on the back substrate side;The display side electrode is grounded,When displaying by the color of the charged particle group, the DC voltage or the first alternating voltage isInsideelectrodeas well asAboveOutsideelectrodeEach ofWhen the display by the color of the colored portion is applied to the second alternating voltage,in frontInner electrodeInAppliedAnd grounding the outer electrodeAnd a voltage applying means for changing at least one of the number of cycles, the frequency, and the voltage value of the second alternating voltage according to image information.
[0009]
  According to the present invention, the image display medium is different in color from the colored portion between the display substrate and the back substrate.ElectrificationThe particle group is encapsulated.ElectrificationThe particle group is enclosed so as to be movable between the substrates by an electric field formed by a voltage applied between the substrates. The coloring portion may be provided on the back substrate or may be provided separately from the back substrate, but the back substrate may also serve as the coloring portion. That is, the back substrate itself may be colored, and the color of the back substrate material itselfElectrificationIt may be different from the color of the particle group.
[0010]
  Note that the display substrate has a light-transmitting property, and can be formed of, for example, a glass substrate that is transparent, translucent, or colored and transparent, or a dielectric such as an insulating resin. Also,ElectrificationAs the particles, for example, insulating particles or conductive particles can be used. In addition, an electrode for forming an electric field between the display substrate and the back substrateThe image display medium includes a display-side electrode provided on the display substrate side, and a back-side electrode including an inner electrode and an outer electrode provided on the rear substrate side. These electrodesMay be provided on the opposing surface of the display substrate and the back substrate, respectively, on the surface opposite to the opposing surface of the display substrate and the back substrate, that is, on the outer surface, or in the substrate. May.
[0011]
  ElectrificationWhen there is one kind of particle group,ElectrificationAn image can be displayed with the contrast between the particles and the color of the colored portion. As described in claim 4, a plurality of types having different colors and charging characteristicsElectrificationWhen using particle swarms, different typesElectrificationParticle contrast orElectrificationAn image can be displayed based on the contrast between the particle group and the colored portion. Further, as described in claim 5, white and blackElectrificationBy using the particle group, it is possible to display an achromatic color and display with high whiteness and blackness.
[0012]
  The display side electrode is grounded,The voltage application means applies the DC voltage or the first alternating voltage when performing display by the color of the charged particle group.Insideelectrodeas well asAboveOutsideelectrodeEach ofApply to. For example, when displaying the color of the positively charged charged particle group, a negative DC voltage is applied to the display substrate side. Alternatively, for example, a first alternating voltage of about several cycles is applied, and the final pulse is set to a negative voltage. Thereby, the positively charged charged particle group moves to the display substrate side.
[0013]
  Meanwhile, negatively chargedElectrificationWhen displaying the color of the particle group, a positive DC voltage is applied to the display substrate side. Alternatively, for example, a first alternating voltage of about several cycles is applied, and the final pulse is set to a positive voltage. This caused a negative chargeElectrificationThe particle group moves to the display substrate side. In this way, the desiredElectrificationThe color of the particle group can be displayed. Even after the application of voltage is stopped, due to the adhesion force such as mirror image force or van der Waals force.ElectrificationThe particles remain attached to the display substrate or the back substrate, and the image display is maintained.
[0014]
  In addition, when performing display by the color of the colored portion, the voltage application means uses the second alternating voltage for moving the charged particle group to the surroundings as the second alternating voltage.in frontInner electrodeInAppliedAnd grounding the outer electrodeTo do. Thereby, the charged particle group moves to the periphery, the colored portion is exposed, and the color of the colored portion can be visually recognized from the display substrate side.
[0015]
  The relationship between the cycle number, frequency, and voltage value of the second alternating voltage and the display density of the colored portion is such that the display density increases as the cycle number, frequency, and voltage value increase. This moves in the parallel direction as the number of cycles, frequency and voltage increases.ElectrificationIt is considered that the amount of particles increases, and as a result, the degree of exposure of the colored portion increases and the display density of the colored portion increases.
[0016]
Therefore, when applying the second alternating voltage, the voltage application means changes at least one of the cycle number, frequency, and voltage value according to the image information (density information). As a result, the color of the colored portion can be controlled in gradation, that is, density, and more colors can be displayed.
[0017]
According to a second aspect of the present invention, the voltage applying unit changes at least two of the cycle number, frequency, and voltage value of the second alternating voltage according to image information. For example, when a nonlinear part exists in the relationship between the cycle number of the second alternating voltage and the display density, the nonlinear part can be corrected to be linear by appropriately changing the frequency and voltage value, for example. it can. As a result, the number of gradations can be increased.
[0018]
  According to a third aspect of the present invention, the voltage application means applies the DC voltage or the first alternating voltage in advance before switching the display when switching the gradation display by the color of the colored portion.Insideelectrodeas well asAboveOutsideelectrodeEach ofAnd the charged particle group is moved to the display substrate side so that the color of the charged particle group is displayed.
[0019]
  According to this invention, before switching the gradation display according to the color of the colored portion, the DC voltage or the first alternating voltage is previously applied to the DC voltage or the first alternating voltage.Insideelectrodeas well asAboveOutsideelectrodeEach ofThe charged particle group is moved to the display substrate side to change the display surface to the same color so that the color of the charged particle group is displayed. That is, since display switching is performed from a state where the arrangement state of the charged particle groups is uniform, more stable gradation display can be performed.
[0020]
  The first1The alternating voltage is not particularly limited in frequency or voltage value, and is the same as the first alternating voltage or the second alternating voltage as long as the charged particle group is moved and the arrangement state of the charged particle group is made uniform. The frequency and the voltage value may be used.
[0021]
The invention according to claim 6 is characterized in that the colored portion includes a region colored in red, green, and blue. Thereby, various colors can be displayed.
[0022]
The invention according to claim 7 is characterized in that the colored portion includes a region colored in yellow, magenta, and cyan. As described above, various colors can be displayed by including the colored portion in yellow, magenta, and cyan that are complementary to red, green, and blue.
[0023]
The invention according to claim 8 is characterized in that the back substrate and the colored portion have light transmittance, and further includes a backlight for irradiating light to the back substrate and the colored portion.
[0024]
According to the present invention, the color of the colored portion can be displayed more clearly by irradiating the back substrate with the light of the backlight.
[0025]
  The invention according to claim 9 is characterized in that the back substrate is transparent and the colored portion is provided behind the back substrate.
  According to the present invention, by providing the colored portion separately and independently behind the back substrate, other colors can be easily displayed simply by replacing the colored portion. In addition, the configuration of the image display medium can be simplified, and manufacturing can be facilitated..
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0027]
As shown in FIG. 1, the image display apparatus 10 includes an image display medium 12 and a voltage application unit 14 as voltage application means. In FIG. 1, only one cell (pixel) is schematically shown for the sake of simplicity. By configuring an image display medium having a large number of cells, a desired image can be displayed.
[0028]
In the image display medium 12, a gap member 20 is provided between a transparent display substrate 16 that forms an image display surface and a back substrate 18, and positively charged black particles 22 are formed in cells formed by the gap member 20. In addition, negatively charged white particles 24 are enclosed.
[0029]
The display substrate 16 has a configuration in which a transparent display side electrode 28 and a transparent insulating layer 30 are formed on a transparent substrate 26. The back substrate 18 has a configuration in which an electrode layer 38 including a back electrode composed of an inner electrode 34 and an outer electrode 36, a coloring portion 40, and a transparent insulating layer 42 are formed on a substrate 32. As shown in FIG. 1B, the inner electrode 34 is made of a rectangular copper thin film, and the outer electrode 36 is made of a rectangular ring-shaped copper thin film.
[0030]
In the present embodiment, as an example, the inner electrode 34 is a 0.9 mm × 0.9 mm square, the outer electrode 36 is a rectangular ring having a width of about 0.1 mm, and the gap between the inner electrode 34 and the outer electrode 36 is 0.03 mm. did.
[0031]
The display-side electrode 28 is grounded, and the inner electrode 34 and the outer electrode 36 are connected to the voltage application unit 14 so that a voltage is applied independently according to image information. .
[0032]
In the present embodiment, the display substrate 16 is produced by using a transparent ITO substrate as the substrate 26 and the display-side electrode 28, for example, and coating the surface with, for example, polycarbonate to form the insulating layer 30. Further, the gap member 20 having a height of 300 μm was formed on the display substrate 16 by so-called photolithography.
[0033]
The back substrate 18 is formed by forming an inner electrode 34 and an outer electrode 36 made of a copper foil film on a substrate 32 made of a glass epoxy substrate, and forming a colored portion 40 (for example, magenta) thereon by printing. Was prepared by forming an insulating layer 42 made of polycarbonate.
[0034]
Then, the two substrates were overlapped so that the electrode surfaces of the substrates face each other, and positively charged black particles 22 and negatively charged white particles 24 were enclosed between the substrates to produce the image display medium 12.
[0035]
In this embodiment, a case where a so-called active matrix method in which a voltage is applied independently for each pixel is used as a voltage application method will be described.
[0036]
In such an image display device 10, when performing white display as shown in FIG. 2, the voltage application unit 14 applies a negative DC voltage (for example, −200 V) to each of the inner electrode 34 and the outer electrode 36. Applied for a predetermined time (for example, 20 msec). As a result, the negatively charged white particles 24 on the back substrate 18 side move to the display substrate 16 side due to the action of the electric field generated between the substrates, and are positively charged on the display substrate side 16 side, as shown in FIG. The black particles 22 thus moved move toward the back substrate 18 and display white. Further, even when an alternating voltage of, for example, several cycles is applied as the first alternating voltage and the final pulse is a negative voltage, the white display state can be similarly obtained.
[0037]
On the other hand, when performing black display as shown in FIG. 3, the voltage application unit 14 applies a positive DC voltage (for example, +200 V) to each of the inner electrode 34 and the outer electrode 36 for a predetermined time (for example, 20 msec). . As a result, the positively charged black particles 22 on the back substrate 18 side move to the display substrate 16 side due to the action of the electric field generated between the substrates, and are negatively charged on the display substrate side 16 side, as shown in FIG. The white particles 24 thus moved move toward the back substrate 18 and display black. Further, for example, an alternating voltage of about several cycles is applied as the first alternating voltage, and the black pulse can be similarly displayed even when the final pulse is a positive voltage.
[0038]
Even after the application of the voltage is stopped, the particles remain attached to the display substrate 16 or the back substrate 18 due to adhesion force such as mirror image force or van der Waals force, and the display state is maintained.
[0039]
As shown in FIG. 4, when the black particles 22 and the white particles 24 are retracted to the outside of the cell and the color of the coloring portion 40 is displayed, the voltage application portion 14 causes the inner electrode 34 to have a second alternating shape. A voltage (for example, ± 200 V, frequency 200 Hz, cycle number 50) is applied, and the outer electrode 36 is grounded. As a result, as shown in FIG. 4, the black particles 22 and the white particles 24 move in a direction parallel to the substrate surface, and gather on the grounded outer electrode 36 side, that is, between the substrates where no electric field is generated. Therefore, almost no particles are present on the inner electrode 34, and the color of the colored portion 40 can be viewed from the display substrate 16 side.
[0040]
In addition, when the second alternating voltage is applied to the inner electrode 34 and the outer electrode 36 from this state, the particles gathered on the outer electrode 36 are dispersed to return the particle distribution to a uniform state. Can do.
[0041]
Here, FIG. 5 shows the relationship between the number of cycles of the second alternating voltage and the display density of the colored portion 40 when the frequency is constant (200 Hz) and the amplitude is constant (± 200 V), and FIG. 6 shows the voltage application time. FIG. 7 shows the relationship between the frequency of the second alternating voltage and the display density of the colored portion 40 when the amplitude is constant (200 msec) and the amplitude is constant (± 200 V). FIG. 7 shows a constant frequency (200 Hz) and a constant number of cycles (30 The relationship between the amplitude of the second alternating voltage and the display density of the colored portion 40 in the case of (time) is shown. The display density was measured using X-Rite 404 (manufactured by X-Rite).
[0042]
5-7, it turns out that the area | region where the display density of the color of the coloring part 40 becomes high gradually exists as the cycle number of the 2nd alternating voltage, a frequency, and an amplitude increase.
[0043]
As shown in FIG. 5, the display density is substantially constant when the number of cycles of the second alternating voltage is in the range of 0 to 10 and in the range of 40 or more, but the number of cycles increases in the range of 10 to 40 cycles. Accordingly, the display density increases almost linearly.
[0044]
Further, as shown in FIG. 6, the display density is substantially constant in the range of the frequency of the second alternating voltage from 0 to 50 and in the range of 200 or more, but as the frequency increases in the range of 50 to 200, the frequency is increased. The display density increases almost linearly.
[0045]
Further, as shown in FIG. 7, the display density is substantially constant when the amplitude of the second alternating voltage is in the range of 0 to 100 and in the range of 500 or more, but as the frequency increases in the range of 100 to 500, as shown in FIG. The display density increases almost linearly.
[0046]
Accordingly, at least one of the relationship between the number of cycles of the second alternating voltage and the display concentration, the relationship between the frequency of the second alternating voltage and the display concentration, and the relationship between the amplitude of the second alternating voltage and the display concentration. By controlling at least one of the cycle number, frequency, and amplitude of the second alternating voltage within a range having linearity using the two relationships, the color gradation control, that is, density control of the coloring portion 40 is performed. be able to.
[0047]
For this reason, the voltage application unit 14 controls at least one of the number of cycles, the frequency, and the amplitude of the second alternating voltage according to the image information, and controls the gradation of the color of the coloring unit 40. In particular, when the gradation control is performed by controlling the number of cycles or the frequency of the second alternating voltage, the gradation control can be performed with a voltage value sufficient to move the particles. Is preferable since the display density is high and there is almost no unevenness in display density.
[0048]
In this way, the voltage application unit 14 controls the color density of the coloring unit 40 by changing at least one of the cycle number, frequency, and amplitude of the second alternating voltage according to the image information. Gradation control can be performed without lowering.
[0049]
Note that the color gradation control of the coloring unit 40 may be performed by controlling at least two of the cycle number, frequency, and amplitude of the second alternating voltage in accordance with the image information. For example, the nonlinear part in the relationship between the cycle number of the second alternating voltage and the display density can be corrected so that the nonlinear part becomes linear by appropriately changing the frequency and voltage value. As a result, the dynamic range can be expanded.
[0050]
Moreover, when switching the gradation display by the color of the coloring part 40, it is preferable to switch the display after the white display state or the black display state is once set. This makes it possible to perform more stable gradation display in which display switching is performed from a state where the arrangement state of the particle groups is uniform.
[0051]
In addition, as shown in FIG. 7, the colored portion 40 has a configuration in which a colored portion 40Y colored yellow, a colored portion 40M colored magenta, and a colored portion 40C colored cyan are regularly arranged. A back side electrode composed of the display side electrode 28, the inner electrode 34 and the outer electrode 36 may be provided corresponding to each colored portion, and the cells 44Y, 44M and 44C may be formed for each colored portion. Then, as shown by the dotted lines in FIG. 9, one pixel is constituted by the cells 44Y, 44M, and 44C, and the particle movement of an arbitrary cell and the display density of the colored portion are controlled according to the color image information. Colors can be displayed. Further, instead of yellow, magenta, and cyan, red, green, and blue colored portions that are complementary to each other may be used.
[0052]
Further, the substrate 32, the electrode layer 38, and the insulating layer 42 of the back substrate 18 are made transparent, and the colored portions 40Y, 40M, and 40C are translucent. As shown in FIG. It is good also as a structure which provided the backlight 46 in the back. In this case, by irradiating the back substrate 18 with light from the backlight 46 and retracting desired cell particles to the surroundings, the color of the colored portion of the cell can be displayed brighter. Also, as shown in FIG. 11, R (Y + M) can be displayed, for example, by retracting the particles in the adjacent cells 44Y and 44M to the surroundings.
[0053]
Further, as shown in FIG. 12, the back substrate 18 is made transparent, and the coloring portion 40 is not provided in the back substrate 18 but is provided separately from the back substrate 18 and is arranged behind the back substrate 18. Also good. Thereby, it is possible to easily display other colors simply by replacing the coloring unit 40. Further, the production of the image display medium 12 can be facilitated.
[0054]
In the present embodiment, the present invention is applied to an image display apparatus using an image display medium having a configuration in which a rectangular inner electrode 34 and a rectangular ring-shaped outer electrode 36 are provided for one cell and one kind of coloring portion is provided. However, the present invention is not limited to this. For example, as described in Japanese Patent Application No. 2002-250214 proposed by the present inventors, an image using an image display medium having a configuration in which colored portions of a plurality of types of colors are regularly arranged in one cell. The present invention can also be applied to a display device.
[0055]
FIG. 13A shows the configuration of one cell of such an image display medium 50. The image display medium 50 includes a gap member 56 for maintaining a constant gap between the transparent display substrate 52 on the image display side and the colored rear substrate 54 facing the transparent display substrate 52 with a minute gap. For example, negatively charged white particles 58 and positively charged black particles 60 having different charging characteristics are enclosed.
[0056]
The back substrate 54 has a configuration in which a glass substrate 62, an ITO conductive film 64, a white reflective layer 66, and a colored layer 68 are laminated.
[0057]
FIG. 13B shows a plan view of the back substrate 54. As shown in FIG. 13B, in the colored layer 68, a rectangular red colored portion 68R, a rectangular green colored portion 68G, and a rectangular blue colored portion 68B are regularly arranged. .
[0058]
FIG. 14 shows a schematic configuration of an image display device 70 using the image display medium 50. The image display device 70 includes an image display medium 50, a voltage application unit 72, and an electrode head 74. In FIG. 14, the image display medium 50 and the electrode head 74 are shown for one cell.
[0059]
The voltage application unit 72 controls the electrode head 74 based on the image information input from the image input device 75.
[0060]
As shown in FIG. 15, the electrode head 74 is configured by arranging isolated electrodes 76 to which a voltage can be independently applied in one row at a predetermined interval. An image is formed by applying a voltage to the isolated electrode 76 in accordance with image information while moving the electrode head 74 along the display surface of the image display medium 50 as shown in FIG.
[0061]
Next, an image display method of the image display medium 50 will be described.
[0062]
From the white display state shown in FIG. 14, when the isolated electrodes 76A and 76C of the electrode head 74 are grounded and a pulse voltage of, for example, −200 V is applied to the isolated electrode 76B, the section on the colored portion 68G is shown in FIG. Then, the black particles 60 move to the display substrate 52 side. Further, when a pulse voltage of, for example, +200 V is applied to the isolated electrode 76B, the display state shown in FIG. 17 can be returned to the white display state shown in FIG.
[0063]
Similarly, a black and white image with high contrast can be displayed by applying a +200 V or −200 V pulse voltage to an arbitrary isolated electrode 76 in accordance with image information.
[0064]
Further, when the isolated electrodes 76A and 76C of the electrode head 74 are grounded and an alternating voltage of ± 200 V and a frequency of 200 Hz is applied to the isolated electrode 76B, as shown in FIG. 18, white particles 58 in the section on the colored portion 68G are obtained. In addition, the black particles 60 move to the sections on the colored portions 68R and 68B and almost no longer exist, and the color green of the colored portion 68G can be visually recognized from the display substrate 52 side.
[0065]
Further, when the isolated electrode 76C of the electrode head 74 is grounded and an alternating voltage is applied to the isolated electrodes 76A and 76B, as shown in FIG. 19, the white particles 58 and the black particles 60 in the sections on the colored portions 68R and 68G are formed. After moving to the section on the colored portion 68B, it almost disappears, and the Y color combining the R color and the G color, which are the colors of the colored portions 68R and 68G, is displayed.
[0066]
Even in the image display device having such a configuration, when displaying the color of the colored portion, the gradation control of the color of the colored portion is performed by controlling at least one of the cycle number, frequency, and amplitude of the alternating voltage described above. Can be performed.
[0067]
In addition to the configuration in which a voltage is applied while moving the electrode head 74 in a predetermined direction, a plurality of line-shaped back side electrodes having the same shape are provided on the back substrate 54 corresponding to the colored portions 68R, 68G, 68B. In addition, when the image display medium 50 is viewed in plan, a plurality of line-shaped display side electrodes orthogonal to the back side electrodes may be provided on the display substrate 52 to drive a so-called passive matrix (simple matrix).
[0068]
In the present embodiment, the case where two types of particles are used has been described. However, the present invention is not limited to this, and one type or three or more types of particles may be used.
[0069]
【The invention's effect】
According to the present invention, there is an effect that more colors can be displayed without reducing the resolution.
[Brief description of the drawings]
FIG. 1A is a schematic configuration diagram of an image display device, and FIG. 1B is a plan view showing an arrangement of coloring portions and electrode layers.
FIG. 2 is a schematic configuration diagram of an image display device.
FIG. 3 is a schematic configuration diagram of an image display device.
FIG. 4 is a schematic configuration diagram of an image display device.
FIG. 5 is a graph showing the relationship between the cycle number of the alternating voltage and the display density of the color of the colored portion.
FIG. 6 is a graph showing the relationship between the frequency of the alternating voltage and the display density of the color of the colored portion.
FIG. 7 is a graph showing the relationship between the amplitude of the alternating voltage and the display density of the color of the colored portion.
FIG. 8 is a cross-sectional view of an image display medium.
FIG. 9 is a diagram showing an arrangement of cells.
FIG. 10 is a cross-sectional view of an image display medium.
FIG. 11 is a cross-sectional view of an image display medium.
FIG. 12 is a cross-sectional view of an image display medium having a configuration in which a coloring portion and a back substrate are separated.
13A is a cross-sectional view of an image display medium, and FIG. 13B is a plan view of a back substrate.
FIG. 14 is a schematic configuration diagram of an image display device.
FIG. 15 is a schematic configuration diagram of an electrode head.
FIG. 16 is a diagram for explaining scanning of an electrode head.
FIG. 17 is a schematic configuration diagram of an image display device.
FIG. 18 is a schematic configuration diagram of an image display device.
FIG. 19 is a schematic configuration diagram of an image display device.
[Explanation of symbols]
10 Image display device
12 Image display media
14 Voltage application section
16 Display board
18 Back substrate
20 Gap member
22 Black particles
24 white particles
26 and 32 substrates
28 Display side electrode
30, 42 Insulating layer
34 Inner electrode
36 outer electrode
38 Electrode layer
40 Coloring section
46 Backlight

Claims (9)

Formed by a display substrate having at least translucency, a rear substrate facing the display substrate, a colored portion provided on the rear substrate side, and a voltage applied between the display substrate and the rear substrate. A charged particle group different in color from the colored portion, a display-side electrode provided on the display substrate side, an inner electrode provided on the back substrate side, An image display medium comprising a back-side electrode composed of an outer electrode;
The display-side electrode is grounded, and when displaying by the color of the charged particle group, a DC voltage or a first alternating voltage is applied to each of the inner electrode and the outer electrode , and depending on the color of the colored portion when performing the display, the grounding the second is applied before Symbol inner electrode an alternating voltage and the outer electrode, the number of cycles the second alternating voltage, frequency, and at least one of image information of the voltage value Voltage applying means to be changed according to,
An image display device comprising:   The image display apparatus according to claim 1, wherein the voltage applying unit changes at least two of the cycle number, frequency, and voltage value of the second alternating voltage according to image information. The voltage application means applies the DC voltage or the first alternating voltage to each of the inner electrode and the outer electrode in advance before switching the display when switching the gradation display by the color of the colored portion. The image display device according to claim 1, wherein the charged particle group is moved toward the display substrate so that the color of the charged particle group is displayed.   The image display device according to claim 1, wherein the charged particle group is a plurality of types of charged particle groups having different colors and charging characteristics.   The image display apparatus according to claim 4, wherein the plurality of types of charged particle groups include white and black charged particle groups.   The image display device according to claim 1, wherein the colored portion includes a region colored in red, green, and blue.   The image display device according to claim 1, wherein the coloring portion includes a region colored with yellow, magenta, and cyan.   The back substrate and the colored portion have light transmittance, and further includes a backlight for irradiating the back substrate and the colored portion with light. The image display device according to item 1.   9. The image display device according to claim 1, wherein the back substrate is transparent, and the colored portion is provided behind the back substrate. 10.

Images