Image forming unit and image forming device
View Patent ↗An image forming unit has a rotatable electrostatic latent image carrier, a charge member positioned to contact the electrostatic latent image carrier and charge a surface of the electrostatic latent image carrier, and a developing part, which supplies a developer to the electrostatic latent image carrier for obtaining a developer image. The charge member includes a conductive elastic layer and a surface layer formed on a circumferential surface of the conductive elastic layer. The surface layer contains particles having an average particle size of 5 μm-20 μm; and a ratio of a surface area per unit area of the surface layer is in a range from 1.5 to 3.0.
1. An image forming unit, comprising:
a rotatable electrostatic latent image carrier;
a charge member that is positioned to contact the electrostatic latent image carrier and that charges a surface of the electrostatic latent image carrier; and
a developing part that supplies a developer to the electrostatic latent image carrier for obtaining a developer image, wherein
the charge member includes a conductive elastic layer and a surface layer formed on a circumferential surface of the conductive elastic layer;
the surface layer contains particles having an average particle size of 5 μm-20 μm;
a ratio of a surface area per unit area of the surface layer is in a range from 1.5 to 3.0,
the ratio of the surface area per unit area of the surface layer is calculated from a formula Ss/Sa; and
the surface area of the surface layer is Ss and the area of the surface layer is Sa.
2. The image forming unit according to claim 1 , wherein the surface layer is composed with a binder resin and the particles, and the particles are contained in a dispersed manner in the surface layer.
3. The image forming unit according to claim 1 , wherein when the diameter of the particles is D,
a ten-point average roughness of the surface layer Rz is D/2 or greater, and
a maximum height Ry of the surface layer is 2D or less.
4. The image forming unit according to claim 1 , wherein
an outer shape of the charge member is cylindrical,
a shaft extends along an axis of the charge member; and
the conductive elastic layer is formed on an outer circumference of the shaft.
5. The image forming unit according to claim 1 , wherein a surface layer is formed on the outer circumferential surface of the conductive elastic layer.
6. The image forming unit according to claim 1 , wherein an intermediate layer is formed between the conductive elastic layer and the surface layer.
7. The image forming unit according to claim 1 , wherein the particles contain at least any one of carbon black, metal, a metallic oxide and an ionic compound.
8. The image forming unit according to claim 1 , wherein the electrostatic latent image carrier is a photosensitive drum.
9. An image forming unit, comprising:
an electrostatic latent image carrier, wherein an electrostatic latent image is formed on a surface of the electrostatic latent image carrier; and
a rubber roller that contacts the electrostatic latent image carrier, wherein
the rubber roller has an axial shaft, a conductive elastic layer formed about an outer circumference of the shaft, and a surface layer formed on an outer-circumferential surface of the conductive elastic layer;
the surface layer contains particles, which have an average particle size of 5 μm-20 μm, in a dispersed manner;
a ratio of a surface area per unit area of the surface layer is in a range from 1.5 to 3.0;
the ratio of the surface area per unit area of the surface layer is calculated from a formula Ss/Sa; and
the surface area of the surface layer is Ss and the area of the surface layer is Sa.
10. The image forming unit according to claim 9 , wherein the surface layer is composed with a binder resin and the particles, and the particles are contained in a dispersed manner in the surface layer.
11. The image forming unit according to claim 9 , wherein
when the diameter of the particles is D,
a ten-point average roughness of the surface layer Rz is D/2 or greater, and
a maximum height Ry of the surface layer is 2D or less.
12. The image forming unit according to claim 9 , wherein the surface layer is formed on the outer-circumferential surface of the conductive elastic layer.
13. The image forming unit according to claim 9 , wherein at least an intermediate layer is formed between the conductive elastic layer and the surface layer.
14. The image forming unit according to claim 9 , wherein the particles contain at least any one of carbon black, metal, a metallic oxide and an ionic compound.
15. The image forming unit according to claim 9 , wherein the electrostatic latent image carrier is a photosensitive drum.
16. The image forming unit according to claim 1 , wherein the image forming unit is part of an image forming device that includes:
a carrying part that carries a sheet;
a transfer part that transfers the developer image onto the sheet from the image forming unit;
a fusing part that fuses the developer image transferred onto the paper by the transfer part; and
an ejector that ejects the sheet on which the developer image is fused.
17. The image forming unit according to claim 1 , wherein
the surface area being Ss includes a surface area that includes asperity created with particles being dispersed on the surface area; and
the area being Sa is a flat surface area that excludes the asperity created with the particles.
18. The image forming unit according to claim 9 , wherein
the surface area being Ss includes a surface area that includes asperity created with particles being dispersed on the surface area; and
the area being Sa is a flat surface area that excludes the asperity created with the particles.