Colorant, particles for display device, image display medium and image forming apparatus

1. A colorant comprising a particulate base material and particles having the color strength due to the surface plasmon resonance, the particles being supported on or contained in the particulate base material.

2. The colorant of claim 1 , wherein the particles having the color strength due to the surface plasmon resonance are metal colloid particles.

3. The colorant of claim 2 , wherein the metal colloid particles are gold or silver.

4. The colorant of claim 1 , wherein the particulate base material is an inorganic compound.

5. The colorant of claim 4 , wherein the inorganic compound is at least one compound selected from titanium oxides and zeolite.

6. The colorant of claim 1 , wherein the particulate base material is a polymer compound.

7. The colorant of claim 6 , wherein the polymer compound contains an inorganic white pigment.

8. The colorant of claim 7 , wherein the inorganic white pigment is at least one pigment selected from titanium oxides and zeolite.

9. The colorant of claim 1 , further comprising a coating layer covering the particulate base material.

10. Particles for display device comprising a colorant and a resin, wherein the colorant contains a particulate base material and particles having the color strength due to the surface plasmon resonance, the particles having the color strength due to the surface plasmon resonance being supported on or contained in the particulate base material.

11. An image display medium comprising a pair of substrates disposed so as to face each other and a particle group containing at least two types of display particles, the particle group being sealed in the gap between the pair of substrates, the medium having the characteristics that at least one type among the display particles can be charged positively by external stimulation and at least one other type can be charged negatively by external stimulation, and the color of the display particles which can be charged positively by external stimulation is different from the display particles which can be charged negatively by external stimulation, wherein at least one type of the display particles is particles for display device containing a colorant, and a resin and the colorant contains a particulate base material and particles having the color strength due to the surface plasmon resonance, the particles being supported on or contained in the particulate base material.

12. An image forming apparatus comprising:

an image display medium comprising a pair of substrates disposed so as to face each other and a particle group containing at least two types of display particles, the particle group being sealed in the gap between the pair of substrates, the medium having the characteristics that at least one type among the display particles can be charged positively by external stimulation, and at least one other type can be charged negatively by external stimulation, and the color of the display particles which can be charged positively by external stimulation is different from the display particles which can be charged negatively by external stimulation, wherein at least one type of the display particles is particles for display device containing a colorant and a resin, and the colorant contains a particulate base material and particles having the color strength due to the surface plasmon resonance, the particles being supported on or contained in the particulate base material; and

an electric field generating device that generates an electric field corresponding to image information, the device being interposed between the pair of substrates.