Claims
- 1. A negative developing agent comprising a negative magnetic toner particle including a carrier and a negative magnetic toner containing a coloring agent, a magnetic powder and a binder resin; a negative conductive silica; an inorganic oxide and not containing a charge control agent.
- 2. The negative developing agent according to claim 1, wherein said negative conductive silica consists of a silica fine powder covered with a mixture of tin oxide and antimony.
- 3. The negative developing agent according to claim 1, wherein said negative conductive silica has a 50% volume diameter of 0.02 to 2 μm, and a resistivity of 50 to 500 Ω·cm, and is added in an amount of 0.05 to 2% by weight.
- 4. The negative developing agent according to claim 1, wherein a magnetic powder is added in an amount of 20 to 60% by weight based on the total weight of said toner particle.
- 5. The negative developing agent according to claim 1, wherein said inorganic oxide has a volume average diameter of 4 to 20 nm and is added in an amount of 0.1 to 1% by weight based on the total weight of said toner particle.
- 6. An image forming apparatus, comprising:at least one image carrier; a developing device having a hollow cylindrical rotatable sleeve for holding a developing agent and a developing roller including a magnetic roller having a plurality of magnetic poles and rotatable independent of said sleeve, said developing agent including a negative magnetic toner containing a carrier and a negative magnetic toner particle having a magnetic powder and a binder resin, a negative conductive silica, and an inorganic oxide does not contain a charge control agent; a transfer device, a cleaning device, said developing device, transfer device and cleaning device being arranged to face said image carrier in the order mentioned; and a fixing device arranged downstream of said transfer device and having a pair of fixing rollers.
- 7. The image forming apparatus according to claim 6, wherein said negative conductive silica consists of a fine silica powder covered with a mixture of tin oxide and antimony.
- 8. The image forming apparatus according to claim 6, wherein a toner specific concentration of said toner to said carrier falls within a range of between 20 and 60%.
- 9. The image forming apparatus according to claim 6, wherein said negative conductive silica has a 50% volume diameter of 0.02 to 2 μm, and a resistivity of 50 to 500 Ω·cm, and is added in an amount of 0.05 to 2% by weight.
- 10. The image forming apparatus according to claim 6, wherein a magnetic toner is added in an amount of 20 to 60% by weight based on the total weight of said toner particle.
- 11. The image forming apparatus according to claim 6, wherein said inorganic oxide has a volume average diameter of 4 to 20 nm and is added in an amount of 0.1 to 1% by weight based on the total weight of said toner particle.
- 12. A negative developing agent comprising a negative magnetic toner particle including a carrier and a negative magnetic toner containing a coloring agent, a magnetic powder and a binder resin; a negative conductive silica; and an inorganic oxide, wherein the negative developing agent does not contain a charge control agent, and wherein said magnetic powder is substantially contained inside said negative magnetic toner.
- 13. The negative developing agent according to claim 12, wherein the coloring agent and the binder resin are substantially contained inside said negative magnetic toner.
- 14. The negative developing agent according to claim 12, wherein the negative conductive silica is attached to an exterior surface of the negative magnetic toner.
- 15. The negative developing agent according to claim 12, wherein the inorganic oxide is attached to an exterior surface of the negative magnetic toner.
Priority Claims (1)
Number |
Date |
Country |
Kind |
11-266951 |
Sep 1999 |
JP |
|
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-266951, filed Sep. 21, 1999, the entire contents of which are incorporated herein by reference.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
6183927 |
Magome et al. |
Feb 2001 |
B1 |
Foreign Referenced Citations (2)
Number |
Date |
Country |
3-256052 |
Nov 1991 |
JP |
11-194525 |
Jul 1999 |
JP |