Particle for display device, method for manufacturing particle for display device, image display medium and image forming apparatus

1. Particles for forming an image in a display device comprising a positively or negatively chargeable property and color, wherein an abundance ratio of particles within the display device with a major axis to minor axis length ratio of approximately 1.2 or greater is approximately 5% or less by number, and further comprising, as the white colorant, at least two types of titanium oxide having different average particle diameters.

2. Particles for forming an image in a display device comprising a positively or negatively chargeable property and color, wherein an abundance ratio of particles within the display device with a major axis to minor axis length ratio of approximately 1.2 or greater is approximately 5% or less by number, and further comprising, as the white colorant, titanium oxide with a primary particle diameter of approximately 0.1 to 1.0 μm and titanium oxide with a primary diameter of less than approximately 0.1 μm.

3. Particles for forming an image in a display device comprising a positively or negatively chargeable property and color, wherein an abundance ratio of particles within the display device with a major axis to minor axis length ratio of approximately 1.2 or greater is approximately 5% or less by number, and further comprising approximately 1 to 60% by mass of colorant relative to the total mass of the particles for a display device when the specific gravity of the colorant is 1.

4. Particles for forming an image in a display device comprising a positively or negatively chargeable property and color, wherein an abundance ratio of particles within the display device with a major axis to minor axis length ratio of approximately 1.2 or greater is approximately 5% or less by number, and further comprising a master batch pigment as the colorant.

5. An image display medium comprising at least a pair of substrates disposed opposite each other and particle groups comprising at least two or more types of particles enclosed in a space between pair of substrates, at least one type of the two or more types of the particles having a positively chargeable property while the other at least one type of the particles having a negatively chargeable property, the positively and negatively chargeable particles being colored differently from one another,

both the positively and negatively chargeable particles within the image display medium containing particles having a major axis to minor axis length ratio of approximately 1.2 or greater in a proportion of 5% or less by number.

6. An image display medium according to claim 5 , wherein at least one type of the particles of the two or more types of the particles are white particles.

7. An image display medium according to claim 5 , wherein at least one type of the two or more types of the particles are black particles.

8. An image forming apparatus for forming an image on an image display medium comprising at least a pair of substrates disposed opposite each other and particle groups comprising at least two or more types of particles enclosed in a space between pair of the substrates,

at least one type of the two or more types of the particles having a positively chargeable property while the other at least one type of the particles having a negatively chargeable property,

the positively and negatively chargeable particles being colored differently from one another, and

both the positively and negatively chargeable particles within the image forming apparatus containing particles having a major axis to minor axis length ratio of approximately 1.2 or greater in a proportion of 5% or less by number,

wherein the image forming apparatus comprises an electric field generating unit for generating an electric field corresponding to the image between a pair of substrates.