Reversible image display medium
First Claim
1. A reversible image display medium comprising:
- two substrates opposed to each other with a gap therebetween;
one or more developer accommodating cells formed between the two substrates, each having a periphery surrounded by a partition wall; and
a dry developer contained in each of the cell(s), wherein the dry developer contains at least two kinds of frictionally chargeable dry developing particles having different chargeable polarities and different optical reflection densities, and whereinthe dry developer has an average charge quantity of 1.0 μ
C/g to 10 μ
C/g as determined by an electric field separation measuring method.
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Accused Products
Abstract
A reversible image display medium accommodates a dry developer in each cell formed between two substrates. The developer contains at least two kinds of frictionally chargeable dry developing particles having different chargeable polarities and different optical reflection densities. An image display can be achieved by forming an electrostatic latent image on one of the substrates to drive the developing particles in an electric field based on the electrostatic latent image. The developing particles are set to an average charge quantity of 1.0 μC/g to 10 μC/g to achieve good image display. Optionally at least one kind of the developing particles are magnetic developing particles having a coercive force of 50 oersteds to 250 oersteds, and optionally having an optical reflection density of 1.0 or more. An amount of small-size developing particles and/or an addition of a third component may be adjusted and volume average particle size ratio of developing particles may be controlled.
25 Citations
18 Claims
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1. A reversible image display medium comprising:
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two substrates opposed to each other with a gap therebetween;
one or more developer accommodating cells formed between the two substrates, each having a periphery surrounded by a partition wall; and
a dry developer contained in each of the cell(s), wherein the dry developer contains at least two kinds of frictionally chargeable dry developing particles having different chargeable polarities and different optical reflection densities, and wherein the dry developer has an average charge quantity of 1.0 μ
C/g to 10 μ
C/g as determined by an electric field separation measuring method.
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2. A reversible image display medium comprising:
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two substrates opposed to each other with a gap therebetween;
one or more developer accommodating cells formed between the two substrates, each having a periphery surrounded by a partition wall; and
a dry developer contained in each of the cell(s), wherein the dry developer contains at least two kinds of frictionally chargeable dry developing particles having different chargeable polarities and different optical reflection densities, and wherein at least one kind, among the two kinds, of the developing particles are magnetic developing particles having a coercive force of 50 oersteds to 250 oersteds.
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3. A reversible image display medium comprising:
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two substrates opposed to each other with a gap therebetween;
one or more developer accommodating cells formed between the two substrates, each having a periphery surrounded by a partition wall; and
a dry developer contained in each of the cell(s), wherein the dry developer contains at least two kinds of frictionally chargeable dry developing particles having different chargeable polarities and different optical reflection densities, and wherein at least one kind, among the two kinds, of the developing particles are magnetic developing particles having an optical reflection density of 1.0 or more. - View Dependent Claims (4)
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5. A reversible image display medium comprising:
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two substrates opposed to each other with a gap therebetween;
one or more developer accommodating cells formed between the two substrates, each having a periphery surrounded by a partition wall; and
a dry developer contained in each of the cell(s), wherein the dry developer contains at least two kinds of frictionally chargeable dry developing particles a and b having different chargeable polarities and different optical reflection densities, and wherein conditions represented by following formula 1 and formula 2 are satisfied concerning the cell;
- View Dependent Claims (6)
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7. A reversible image display medium comprising:
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two substrates opposed to each other with a gap therebetween;
one or more developer accommodating cells formed between the two substrates, each having a periphery surrounded by a partition wall; and
a dry developer contained in each of the cell(s), wherein the dry developer contains at least two kinds of frictionally chargeable dry developing particles having different chargeable polarities and different optical reflection densities, and wherein at least one kind of the dry developing particles are non-magnetic developing particles, and an amount of the non-magnetic developing particles having a particle size of 3 μ
m or less in volume particle size distribution of the non-magnetic developing particles is 0.5 wt % or less.- View Dependent Claims (8)
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9. A reversible image display medium comprising:
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two substrates opposed to each other with a gap therebetween;
one or more developer accommodating cells formed between the two substrates, each having a periphery surrounded by a partition wall; and
a dry developer contained in each of the cell(s), wherein the dry developer contains at least two kinds of frictionally chargeable dry developing particles having different chargeable polarities and different optical reflection densities, and wherein at least one kind of the dry developing particles are magnetic developing particles, and an amount of the magnetic developing particles having a particle size of 4 μ
m or less in volume particle size distribution of the magnetic developing particles is 1 wt. % or less.
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10. A reversible image display medium comprising:
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two substrates opposed to each other with a gap therebetween;
one or more developer accommodating cells formed between the two substrates, each having a periphery surrounded by a partition wall; and
a dry developer contained in each of the cell(s), wherein the dry developer contains at least two kinds of frictionally chargeable dry developing particles having different chargeable polarities and different optical reflection densities, and wherein a third component is added to at least one kind of the dry developing particles, and in each of the third component-added developing particles, an addition proportion of the third component to the developing particles having a particle size of 5 μ
m or less in volume particle size distribution of the developing particles is different from an addition proportion of the third component to the developing particles having a particle size of more than 5 μ
m in the volume particle size distribution such that an adhesion of the particles of 5 μ
m or less in particle size can be reduced to a larger extent than when employing the same addition proportion of the third component to the developing particles of 5 μ
m or less in particle size as the proportion of the third component to the developing particles of more than 5 μ
m in particle size.- View Dependent Claims (11, 12, 13, 17)
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14. A reversible image display medium comprising:
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two substrates opposed to each other with a gap therebetween;
one or more developer accommodating cells formed between the two substrates, each having a periphery surrounded by a partition wall; and
a dry developer contained in each of the cell(s), wherein the dry developer contains at least two kinds of frictionally chargeable dry developing particles having different chargeable polarities and different optical reflection densities, and wherein third components are added to at least one kind of the dry developing particles, and in each of the third component-added developing particles, the third component to be added to the developing particles having a particle size of 5 μ
m or less in volume particle size distribution of the developing particles is different from the third component to be added to the developing particles having a particle size of more than 5 μ
m in the volume particle size distribution such that an adhesion of the particles of 5 μ
m or less in particle size can be reduced to a larger extent than when adding the same third component to the developing particles of 5 μ
m or less in particle size as the third component to be added to the developing particles of more than 5 μ
m in particle size.- View Dependent Claims (15, 16)
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18. A reversible image display medium comprising:
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two substrates opposed to each other with a gap therebetween;
one or more developer accommodating cells formed between the two substrates, each having a periphery surrounded by a partition wall; and
a dry developer contained in each of the cell(s), wherein the dry developer contains at least two kinds of frictionally chargeable dry developing particles having different chargeable polarities and different optical reflection densities, and wherein at least one kind, among the two kinds, of the developing particles are magnetic developing particles, and a ratio of volume average particle size in the two kinds of the dry developing particles (=volume average particle size of the magnetic developing particles/volume average particle size of the other developing particles) is in a range of 0.5 to 10.
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Specification