JP2002287175A - Twisting ball display sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a twisting ball display sheet which can stably keep an image even when accidental triboelectrification or dissipation of retention charges occurs after the image is written. SOLUTION: The twisting ball display sheet 10 has a translucent sheet 12 having cavities 14 which are regularly formed and arranged, color balls 16 housed in the cavities 14, each having two surfaces with different optical characteristics and electrification characteristics from each other and rotatable by an electric effect, an insulating liquid 18 filling the space between the inner wall faces of the cavities 14 and the color balls 16, and polymer gel particles 26 dispersed in the insulating liquid 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes a cavity filled with an insulating liquid containing a colored ball having partially different charging characteristics. Including text)
And a twisting ball display sheet.

[0002]

2. Description of the Related Art Conventionally, a twisting ball display sheet having a partial cross section as shown in FIG.
11) is known. The sheet 11 comprises a light-transmitting sheet 12 made of a material such as an elastomer. In the translucent sheet 12, a large number of cavities 14 having a spherical inside are arranged regularly (for example, in a lattice). The cavity 14 accommodates a colored ball 16. The cavity 14 is formed slightly larger than the size of the colored ball 16. An insulating liquid 18 is filled between the inner wall surface of the cavity 14 and the colored ball 16.
Each of the cavities 14 forms a pixel in the sheet 11.

[0003] The colored ball 16 has two surfaces having different optical characteristics. Specifically, the colored ball 16 has a white hemisphere 16w on one side and a black hemisphere on the other side. These colors may be colored by separately applying paint or the like to each surface of both hemispheres, or by applying paint or the like only to the surface of one hemisphere, or a material constituting each hemisphere. It may be colored by adding a pigment such as a pigment to each. The colored ball 16
Has a diameter of several tens μm or less, preferably 10 to 20 μm.
m.

The colored ball 16 has two surfaces having different charging characteristics, that is, a white hemisphere surface and a black hemisphere surface. As a result, a dipole moment is generated inside the colored ball 16. As a method of generating the dipole moment as described above, each of the hemispheres 16w, 16w
b, each surface is coated with a film having a different zeta potential, the ball is formed of a ferroelectric material and polarized in a direction opposite to each hemisphere, and each hemisphere 16w, 16b is formed of a material having a different work function. And so on. When a predetermined electric field is applied to the colored ball 16 in which the dipole moment is generated, the colored ball 16 rotates. Here, it is assumed that the white hemisphere 16w has a positive (+) charge and the black hemisphere 16b has a negative (-) charge.

[0005] A method for manufacturing such a sheet 11 or colored balls 16 is disclosed in, for example, US Pat. No. 4,126,85.
4, JP-A-10-214050, JP-A-10-33
No. 3608 and the like, which are known.

In the sheet 11 having the above-described structure, by applying a predetermined electric field before image formation, as shown in FIG. 12, all the colored balls 16 face each white hemisphere 16w in the same direction. It turns and is aligned. Thereby, the sheet 11 is moved upward (X direction, FIG. 13).
), The entire sheet appears white. As shown in FIG. 13, the external electrodes 20 and 2 disposed with the sheet 11 interposed between the sheet 11 in this state.
When an electric field 24 is applied to the desired cavity 14 according to 2,
The negatively charged black hemisphere 16b is attracted to the electrode 20 to which the positive voltage is applied, and the positively charged white hemisphere 16w is attracted to the electrode 2 to which the negative voltage is applied.
Attracted to 2. Thereby, the colored ball 16 becomes
The black hemisphere 16b rotates so as to face the electrode 20, and when the sheet 11 is viewed from above, it appears as a black dot. In this way, a desired image can be displayed on the sheet 11 by selectively rotating a large number of the colored balls 16.

[0007] The image displayed in this manner is held by the colored electrodes 16 being kept from rotating by the held charges applied to the surface of the sheet 11 by the external electrodes 20 and 22.

[0008]

However, in the sheet 11 on which an image is displayed as described above, when an accidental triboelectric charge or loss of the retained charge due to rubbing with a hand or the like occurs, the image display section or the non- There is a problem that the colored ball of the image display unit may rotate, and the image cannot be stably held.

[0009]

In order to solve the above-mentioned problems, a first twisting ball display sheet of the present invention comprises a light-transmitting sheet having cavities arranged in a regular array; Housed in
A colored ball having at least two surfaces having different optical characteristics and charging characteristics and being rotatable by an electric action; an insulating liquid filled between the inner wall surface of the cavity and the colored ball; A reversible volume change substance dispersed in a liquid.

[0010] A second twisting ball display sheet of the present invention comprises a light-transmitting sheet having cavities arranged in a regular array, and at least two light-transmitting sheets housed in the cavities and having different optical characteristics and charging characteristics. A colored ball having two surfaces and rotatable by an electric action, and an insulating liquid filled between the inner wall surface of the cavity and the colored ball, and all or a part of the colored ball is reversible. It is characterized by being composed of a material with a variable volume.

In the first and second twisting ball display sheets according to the present invention, the reversible volume change material may change its volume by heat.

A third twisting ball display sheet according to the present invention comprises a light-transmitting sheet having cavities regularly arranged, and at least two light-transmitting sheets housed in the cavities and having different optical characteristics and charging characteristics. A colored ball rotatable by electric action, and an insulating liquid filled between the inner wall surface of the cavity and the colored ball, wherein at least a part of the inner wall of the cavity is reversible. Characterized by being formed of a dynamic volume change substance.

[0013] In the third twisting ball display sheet of the present invention, the reversible volume change material may change its volume by heat or light.

[0014]

According to the first twisting ball display sheet of the present invention, at the time of writing an image, the reversible volume change substance dispersed in the insulating liquid around the colored balls is contracted. As a result, the frictional resistance with the reversible volume change substance is reduced, and the colored balls are rotatable in the insulating liquid. On the other hand, after completion of the image writing, the reversible volume change substance is expanded so as to be in contact with the surface of the colored ball and the inner wall surface of the cavity. As a result, the colored ball rotated to the state in which the image is displayed is suppressed from rotating due to an increase in the frictional resistance with the reversible volume change substance, and is kept in that state. This is the same for the colored balls in the non-image display section. Therefore, according to the first twisting ball display sheet of the present invention, the colored ball does not rotate and the image is stably held even if accidental triboelectric charge or loss of the retained charge occurs after writing the image. be able to.

In the second twisting ball display sheet of the present invention, all or a part of the colored ball is made of a reversible volume change material. The contact makes it rotatable in the insulating liquid, and after the image writing is completed, the colored ball itself is expanded to make contact with the inner wall surface of the cavity to increase the frictional resistance, thereby suppressing the rotation. Therefore, according to the second twisting ball display sheet of the present invention, the colored ball does not rotate even if there is accidental electrification friction or loss of retained charge after image writing, and the image is stably held. be able to.

In the third twisting ball display sheet of the present invention, at least a part of the inner wall of the cavity is made of a reversible volume changing material, and the inner wall made of the reversible volume changing material is expanded or expanded at the time of image writing. The colored ball is made to be rotatable in the insulating liquid by contracting and making it not contact with the inner wall surface of the cavity, and after the image writing is completed, the inner wall portion is contracted or expanded to make contact with the inner wall surface of the cavity to cause friction. The rotation of the colored ball is suppressed by increasing the resistance. Therefore, according to the second twisting ball display sheet of the present invention, the colored ball does not rotate even if there is accidental electrification friction or loss of retained charge after image writing, and the image is stably held. be able to.

[0017]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Note that components common to the twisting ball display sheet 11 described in the section of the related art will be described using the same reference numerals.

FIG. 1 shows a partial cross section of a twisting ball display sheet 10 of the first embodiment. This sheet 10 is substantially transparent and has a hardness lower than that of a colored ball described later, and causes a thermoplastic elastomer which undergoes reversible deformation.
(Eg, styrene-butadiene-styrene (SBS)) or a translucent sheet 12 made of a material such as a rubber material.
Consists of In the translucent sheet 12, a large number of cavities 14 having a spherical inside are arranged regularly (for example, in a lattice). In the cavity 14, a colored ball 16 is provided.
Is housed. The cavity 14 has a colored ball 16
It is formed slightly larger than the size. The space between the inner wall surface of the cavity 14 and the colored ball 16 is filled with an insulating liquid 18 such as silicone oil.
In the insulating liquid 18, polymer gel particles 26, which are reversible volume change substances, are dispersed. Each of the cavities 14 forms a pixel in the sheet 10.

The colored ball 16 has two surfaces having different optical characteristics. Specifically, the colored ball 16 has a white hemisphere 16w on one side and a black hemisphere on the other side. These colors are colored by including white pigment particles in the polymer that is the constituent material of the white hemisphere 16w and by including black pigment particles in the polymer that is the constituent material of the black hemisphere 16b. As a constituent material of the colored ball 16, styrene resin, styrene-acrylate resin, sodium sulfonated polyester, styrene-methacrylate resin, styrene-methacrylate-acrylic acid terpolymer, or the like is used. The colored ball 16
Has a diameter of several tens μm or less, preferably 10 to 20 μm.
m.

The colored ball 16 has two surfaces having different charging characteristics, that is, a white hemisphere surface and a black hemisphere surface. As a result, a dipole moment is generated inside the colored ball 16. As a method of generating the dipole moment as described above, each of the hemispheres 16w, 16w
b, each surface is coated with a film having a different zeta potential, the ball is formed of a ferroelectric material and polarized in a direction opposite to each hemisphere, and each hemisphere 16w, 16b is formed of a material having a different work function. And so on. When a predetermined electric field is applied to the colored ball 16 in which the dipole moment is generated, the colored ball 16 rotates. Here, it is assumed that the white hemisphere 16w has a positive (+) charge and the black hemisphere 16b has a negative (-) charge.

The polymer gel particles 26 reversibly change in volume, such that when heated, the insulating gel 18 escapes and contracts, and when the temperature returns to normal temperature, the insulating gel 18 absorbs and expands. Having. As a polymer gel material having such properties, a crosslinked polymer having a LCST (lower critical eutectic temperature) is preferable. Specific compounds include [N-
Alkyl-substituted (meth) acrylamide] and N-
Cross-linked product of a copolymer of two or more components such as alkyl-substituted (meth) acrylamide and (meth) acrylic acid and a metal salt thereof, or (meth) acrylamide or alkyl (meth) acrylate, cross-linked product of polyvinyl methyl ether , Methylcellulose, ethylcellulose,
A crosslinked product of an alkyl-substituted cellulose derivative such as hydroxypropylcellulose can be used.

Next, the operation of the seat 10 having the above configuration will be described. The sheet 10 is subjected to a predetermined electric field before image formation, as shown in FIG.
All colored balls 16 are each white hemisphere 16w
Are turned in the same direction. Thereby, when the sheet 10 is viewed from the sheet surface 12a side,
The entire sheet looks white.

At the time of writing an image on the sheet 10 in this state, as shown in FIG. 2, heat is applied to the sheet 10 and external electrodes 20 and 22 sandwiching the sheet 10 interpose the desired cavity 14. An electric field 24 is applied. Due to the heating, the polymer gel particles 26 in the cavity 14 escape from the insulating liquid 18 and contract. Thereby, the frictional resistance with the polymer gel 26 is reduced, and the colored ball 16 is in a rotatable state.

In the colored ball 16 thus rotatable, the negatively charged black hemisphere 16b is moved by the action of the electric field 24 to the electrode 2 to which the positive voltage is applied.
While being attracted to 0, the positively charged white hemisphere 16w is attracted to the electrode 22 to which a negative voltage is applied. As a result, the colored ball 16 becomes the black hemisphere 1
6b is rotated to face the electrode 20, and the sheet surface 1
When viewed from the 2a side, it looks like a black dot. The colored balls 16 rotated by the electric field 24 are connected to the external electrodes 20 and 2.
The rotation of the sheet 10 is suppressed by holding electric charges (shown by + and-) applied to the front surface 12a and the back surface 12b of the sheet 10 and the sheet 10 is held. A desired image can be written on the sheet 10 by selectively rotating the large number of colored balls 16 in this manner.

After the image is written in this manner, the sheet 10 is returned to a generally used environment (normal temperature).
Then, as shown in FIG. 3, the polymer gel particles 26 expand by absorbing the insulating liquid 18 and come into contact with the surface of the colored ball 16 and the inner wall surface of the cavity 14. As a result, the colored ball 16 is prevented from rotating due to an increase in the frictional resistance with the polymer gel particles 26, and is held as it is. Colored ball 16 in this case
Is stronger than that of the case only due to the retained charges. In addition, the colored ball 16 in the non-image portion which did not rotate due to no application of the electric field, ie, the white hemisphere 1
The colored balls 16 with the 6w facing the sheet surface 12a are also held by the swollen polymer gel particles 26 with their rotation suppressed. Therefore, according to the sheet 10, even if accidental triboelectric charging or loss of the retained charge occurs after the image writing, the colored ball 16 does not rotate and the image can be stably retained.

Next, a twisting ball display sheet 10a according to a second embodiment will be described. The difference between the sheet 10a and the sheet 10 of the first embodiment is that, as shown in FIG. 4, the polymer gel particles 26 are not dispersed in the insulating liquid 18, and the entire colored ball 16 is heated by heat. It is made of a polymer gel material that contracts as described above.

In the sheet 10a, when heated at the time of writing an image, the colored ball 16 itself shrinks away from the insulating liquid 18. Thereby, the colored balls 16
Is in a non-contact state with the inner wall surface of the cavity 14, and the frictional resistance is greatly reduced, so that the state becomes rotatable. In this state, by applying an appropriate electric field to the desired cavity 14 in the same manner as described for the sheet 10 of the first embodiment, the coloring ball 16 is rotated to write an image. When the sheet 10a is returned to a generally used environment (normal temperature) after the image writing is completed, the colored ball 16 itself absorbs the insulating liquid 18 and expands as shown in FIG. Be in contact.
As a result, the frictional resistance is greatly increased, so that the rotation of the colored ball 16 is suppressed, and the state is maintained as it is. Therefore, even if the sheet 10a accidentally loses the triboelectric charge or the retained charge after the image writing, the colored ball 16 does not rotate and the image can be stably retained.

In the sheet 10a, the colored balls 1
6 was composed of a polymer gel material,
6 may be made of a polymer gel material. For example,
When only the black hemisphere 16b of the colored balls 16 is made of a polymer gel material, the black hemisphere 16b absorbs the insulating liquid 18 and expands at normal temperature. As a result, FIG.
As shown in (1), the colored ball 16 has an egg-like shape, and both ends thereof come into contact with the inner wall surface of the cavity 14, and the rotation of the colored ball 16 is suppressed.

Next, a twisting ball display sheet 10b according to a third embodiment will be described with reference to FIGS. This sheet 10b, as shown in FIG.
The first sheet 12c and the second sheet 12d are formed by bonding only the sheet peripheral portions (not shown) to each other by, for example, ultrasonic welding. First sheet 12
A partition wall 13a serving as an inner wall of the cavity 14 is formed in c. A gap is formed in the partition wall 13. The gap is filled with the polymer gel 28. The partition wall 13 sandwiching the polymer gel 28 from both sides is made of a relatively soft material and expands and contracts as described later.
Also plays the role of supporting. In the cavity 14,
A colored ball 16 is housed and filled with an insulating liquid 18. Note that the first sheet 12c having the partition wall 13 as described above can be formed by precision fine processing using photolithography, etching, or the like.

The polymer gel 28 of this embodiment absorbs the insulating liquid 18 and expands when heat is applied, while the polymer gel 28 releases and contracts the insulating liquid 18 when the temperature returns to room temperature. Has changing properties. This polymer gel 28
As a two-component polymer gel that is hydrogen-bonded to each other
PN (interpenetrating network structure) and the like are preferable. Specific compounds include an IPN compound composed of a crosslinked product of poly (meth) acrylamide and a crosslinked product of poly (meth) acrylic acid, and a partially neutralized product thereof (one in which acrylic acid units are partially metal-chlorinated); Examples include an IPN body composed of a crosslinked body of a copolymer containing (meth) acrylamide as a main component and a crosslinked body of poly (meth) acrylic acid, and a partially neutralized body thereof.

In the sheet 10b having the above structure, at normal temperature before an image is written, the colored ball 16 is not in contact with the partition wall 13, but is held between the first sheet 12c and the second sheet 12d. I have. Before writing an image, by applying a predetermined electric field, all of the colored balls 16 are turned into a white hemisphere 16w by the first sheet 12c.
It is aligned to the side.

When writing an image on the sheet 10b, heat is applied to the sheet 10b. As a result, as shown in FIG.
8, and the cavity 14 expands in the sheet thickness direction. As a result, the colored ball 16 comes into non-contact with the first sheet 12c and the second sheet 12d, and the frictional resistance is greatly reduced, so that the colored ball 16 becomes rotatable. In this state, an image is written by rotating the colored ball 16 by applying an electric field to the desired cavity 14 in the same manner as described for the sheet 10 of the first embodiment. After the image writing is completed, when the sheet 10b is returned to a generally used environment (normal temperature), the polymer gel 28 contracts by removing the insulating liquid 18, and returns to the state shown in FIG. As a result, both the colored ball 16 that rotates to display an image and the colored ball 16 that does not rotate and display a white background are in contact with the first sheet 12c and the second sheet 12d to increase frictional resistance. , The rotation is suppressed and held. Therefore, the sheet 10b of the present embodiment can also stably hold an image even if accidental triboelectric charging or loss of held charge occurs after writing the image.

In the sheet 10b, the gap between the partition walls 13 is filled with the polymer gel 28. However, as shown in FIG. 9, a part of the partition wall 13 itself, which is the inner wall of the cavity, is filled with the polymer gel 28. You may comprise.

In the sheet 10b, a part of the inner wall of the cavity 14 is made of the polymer gel 28 by filling the gap of the partition wall 13, but as shown in FIG. The inner wall of the cavity 14 may be made of polymer gels 28 (only one may be provided). In this case, the polymer gel 28 has the same property (that is, contracts due to heat) as the polymer gel particles 26 in the sheet 10 of the first embodiment, and between the polymer gels 28 and 28 that have expanded at room temperature. The colored ball 16 is held by being sandwiched. Further, as shown in FIG. 11, the entire inner wall of the cavity 14 is
8 may be used. Also in this case, the polymer gel 28
Has the same properties as the polymer gel particles 26 in the sheet 10 of the first embodiment. Accordingly, the polymer gel 28 contracts by heating to make the colored balls 16 rotatable as shown in FIG. 11, and expands at normal temperature to contact the periphery of the balls to hold the colored balls 16. .

In the meantime, in the sheet 10b, a polymer gel whose volume changes by heat is used, but a polymer gel whose volume changes by light may be used instead. Examples of such a polymer gel compound include polyvinyl methyl ether, a leuco body of triphenylmethane, polystyrene in which leuco hydroxide is partially introduced into a side chain, poly (N, N-dimethylacrylamide), polyacrylamide, and the like. There is. When polyvinyl methyl ether is used, when it is irradiated with infrared rays, it absorbs the insulating liquid 18 and expands. Therefore, by writing an image in a state where the infrared rays are irradiated, the same effect as that of the sheet 10b can be obtained. it can.

In the above embodiment and its modifications, the colored ball 16 having two surfaces having different optical characteristics and charging characteristics (that is, a black-and-white colored and positively and negatively charged ball) 16 is used. For the sheet, a colored ball having three or more surfaces having different optical characteristics and charging characteristics may be used.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a twisting ball display sheet according to a first embodiment.

FIG. 2 is a diagram showing a state when an electric field is applied to a desired cavity of the sheet of FIG. 1 to rotate a colored ball.

FIG. 3 is a view showing a state in which colored balls are held by polymer gel particles in the sheet of FIG. 1;

FIG. 4 is a partial cross-sectional view of a twisting ball display sheet according to a second embodiment.

FIG. 5 is a diagram showing a state in which a colored ball is held in a cavity in the sheet of FIG. 4;

FIG. 6 is a view showing a state in which a colored ball is held in a cavity in a modification of the second embodiment.

FIG. 7 is a partial cross-sectional view of a twisting ball display sheet according to a second embodiment.

FIG. 8 is a view showing a state in which a polymer gel has expanded in the sheet of FIG. 7;

FIG. 9 is a view showing a modification of the third embodiment.

FIG. 10 is a view showing another modification of the third embodiment.

FIG. 11 is a view showing still another modification of the third embodiment.

FIG. 12 is a partial cross-sectional view of a conventional twisting ball display sheet.

FIG. 13 is a diagram showing a state in which an electric field is applied to a desired cavity of the sheet of FIG. 12 to rotate a colored ball;

[Explanation of symbols]

10, 10a, 10b: twisting ball display sheet, 12: translucent sheet, 14: cavity,
Reference numeral 16: colored ball, 16b: black hemisphere, 16w: white hemisphere, 18: insulating liquid, 20, 22: external electrode, 2
4 ... electric field, 26 ... polymer gel particles (reversible volume change substance), 28 ... polymer gel (reversible volume change substance).

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideo Yamaki 2-3-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka Inside Osaka International Building Minolta Co., Ltd. (72) Inventor Shigetaka Yoshida Azuchi, Chuo-ku, Osaka-shi, Osaka Osaka International Building Minolta Co., Ltd. (72) Inventor Shinya Matsuura 2-3-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka

Claims (5)

[Claims] 1. A light-transmitting sheet having cavities regularly formed and arranged, and at least two surfaces housed in the cavities and having different optical characteristics and charging characteristics, and rotatable by an electric action. A colored ball, an insulating liquid filled between the inner wall surface of the cavity and the colored ball, and a reversible volume change substance dispersed in the insulating liquid;
Ball with twisting ball display. 2. A light-transmitting sheet having cavities regularly formed and arranged, and at least two surfaces housed in the cavities and having different optical characteristics and charging characteristics, and are rotatable by an electric action. A colored ball, and an insulating liquid filled between the inner wall surface of the cavity and the colored ball, wherein all or a part of the colored ball is made of a reversible volume changing substance. Sting ball display sheet. 3. The twisting ball display sheet according to claim 1, wherein the reversible volume change material changes its volume by heat. 4. A light-transmitting sheet having cavities regularly formed and arranged, and at least two surfaces housed in the cavities and having different optical characteristics and charging characteristics, and rotatable by an electric action. A colored ball, and an insulating liquid filled between the inner wall surface of the cavity and the colored ball, wherein at least a part of the inner wall of the cavity is formed of a reversible volume change material. And twisting ball display sheet. 5. The twisting ball display sheet according to claim 4, wherein the reversible volume change material changes its volume by heat or light.