Image forming apparatus and elastic roller
View Patent ↗A developing agent image is formed by adhering a developing agent onto an electrostatic latent image formed on an image holding material and transferred onto an image forming medium, thereby forming an image. A resistance value ratio of a resistance value of a transfer member arranged so as to face the image holding material when a voltage 1000 V is applied to the transfer member to a resistance value when a voltage 500 V is applied is set to (0.5≦ratio≦0.89). Likewise, a resistance value ratio of a resistance value when 2000 V is applied to that when 1000 V is applied is set to (0.3≦ratio≦0.88). Since a just enough transfer current can be optimally generated, image quality can be improved and an image forming apparatus which does not need a large-capacity power source and an elastic roller are provided.
1. An image forming apparatus which forms a developer image by making a developer adhere onto an electrostatic latent image formed on an image holding body, further transfers the developer image onto an image forming medium by using a transferring member, then forms an image,
wherein the transferring member has a first resistance value when being added by a voltage of 500 V, a second resistance value when being added by a voltage of 1000 V, and a ratio of the second resistance value to the first resistance value between 0.5 and 0.89.
2. The image forming apparatus according to claim 1 ,
wherein the transferring member further has a third resistance value when being added by a voltage of 2000 V and a ratio of the third resistance value to the second resistance value between 0.3 and 0.88.
3. The image forming apparatus according to claim 1 , wherein the transferring member contains a material with electron conductivity.
4. The image forming apparatus according to claim 3 , wherein the material with electron conductivity includes at least one of carbon black, carbon quality fiber, copper particle, silver particle and nickel.
5. The image forming apparatus according to claim 1 , wherein the transferring member contains a material with ion conductivity.
6. The image forming apparatus according to claim 5 , wherein the material with ion conductivity is alkali metal salt.
7. The image forming apparatus according to claim 1 , wherein the transferring member is added by a power source from 500 V to 2000 V.
8. The image forming apparatus according to claim 1 , wherein the transferring member is a transferring roller.
9. The image forming apparatus according to claim 1 , wherein the transferring member is a transfer belt.
10. An image forming apparatus which forms a developer image by making a developer adhere onto an electrostatic latent image formed on an image holding body, further transfers the developer image onto an image forming medium by using a transferring member, then forms an image,
wherein the transferring member has a first resistance value when being added by a voltage of 2000 V, a second resistance value when being added by a voltage of 1000 V, and a ratio of the second resistance value to the first resistance value between 0.3 and 0.88.
11. An elastic roller constructed by forming an elastic layer around an axis made of a metal, having:
at least one material,
wherein the material has a first resistance value when a voltage of 500 V is added, a second resistance value when a voltage of 1000 V is added, and a ratio of the second resistance value to the first resistance value between 0.5 and 0.89.
12. The elastic roller according to claim 11 ,
wherein the material further has a third resistance value when a voltage of 2000 V is added, and a ratio of the third resistance value to the second resistance value between 0.3 and 0.88.
13. The elastic roller according to claim 11 , wherein the material contains a material with electron conductivity.
14. The elastic roller according to claim 13 , wherein the material with electron conductivity includes at least one of carbon black, carbon quality fiber, copper particle, silver particle and nickel.
15. The elastic roller according to claim 11 , wherein the material contains a material with ion conductivity.
16. The elastic roller according to claim 15 , wherein the material with ion conductivity is alkali metal salt.
17. An elastic roller constructed by forming an elastic layer around an axis made of a metal, having:
at least one material,
wherein the material has a first resistance value when a voltage of 2000 V is added, a second resistance value when a voltage of 1000 V is added, and a ratio of the second resistance value to the first resistance value between 0.3 and 0.88.