IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0617024
(2003-07-11)
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우선권정보 |
JP-2002-209509(2002-07-18) |
발명자
/ 주소 |
- Watanabe,Yasunari
- Adachi,Motoki
|
출원인 / 주소 |
|
대리인 / 주소 |
Fitzpatrick, Cella, Harper &
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인용정보 |
피인용 횟수 :
2 인용 특허 :
4 |
초록
▼
Provided is an image forming apparatus including a unit for controlling each voltage value of peak-to-peak voltages of DC and AC voltages applied to a charging unit for charging an image bearing member, in which a residual charge eliminating unit conducts charge elimination on a surface of the image
Provided is an image forming apparatus including a unit for controlling each voltage value of peak-to-peak voltages of DC and AC voltages applied to a charging unit for charging an image bearing member, in which a residual charge eliminating unit conducts charge elimination on a surface of the image bearing member while at least the charging unit undergoes an application of the AC voltage including the peak-to-peak voltage that is, in the case of setting at Vth a discharge start voltage to the image bearing member when applying the DC voltage to the charging unit, twice or smaller than this discharge start voltage Vth. With this image forming apparatus, it is possible to restrain an occurrence of a defect in an image which is attributable to an instability of a charging potential on the image bearing member by stabilizing a potential on the image bearing member at zero even in a case where the AC voltage applied to the charging unit for the image bearing member is the peak-to-peak voltage that is twice or smaller than Vth.
대표청구항
▼
What is claimed is: 1. An image forming apparatus comprising: an image bearing member; charging means, to which a voltage including an AC voltage is applied, for charging the image bearing member; control means for controlling a peak-to-peak voltage of the AC voltage; developing means for developin
What is claimed is: 1. An image forming apparatus comprising: an image bearing member; charging means, to which a voltage including an AC voltage is applied, for charging the image bearing member; control means for controlling a peak-to-peak voltage of the AC voltage; developing means for developing an electrostatic latent image formed on the image bearing member with a developer; and residual charge eliminating means for conducting charge elimination on the image bearing member, wherein the control means controls the peak-to-peak voltage of the AC voltage which is applied to the charging means during an image forming period, on the basis of both an AC current flowing when applying the AC voltage having a voltage level of the peak-to-peak voltage that is less than twice the discharge start voltage Vth of the image bearing member to the charging means during a non-image forming period and another AC current flowing when applying the AC voltage having a voltage level of the peak-to-peak voltage that is equal to or more than twice the discharge start voltage Vth of the image bearing member to the charging means during a non-image forming period, and wherein the residual charge eliminating means conducts charge elimination on an area on the image bearing member that passes through a charging position of the charging means when applying the AC voltage having a voltage level of the peak-to-peak voltage that is less than twice the discharge start voltage Vth of the image bearing member to the charging means. 2. An image forming apparatus according to claim 1, wherein when applying the AC voltage including the peak-to-peak voltage that is equal to or more than twice the discharge start voltage Vth to the charging means during the non-image forming period, a voltage level of a DC voltage applied to the charging means is OV. 3. An image forming apparatus according to claim 1, wherein while the area on the image bearing member is in a developing position of the developing means, a voltage of such a level that a toner of the developer is not adhered to the image bearing member from the developing means, is applied to the developing means. 4. An image forming apparatus according to claim 1, wherein while the area on the image bearing member is in a developing position of the developing means, a voltage applied to the developing means is OV. 5. An image forming apparatus according to claim 2, wherein while the area on the image bearing member and an area on the image bearing member that is charged by the charging means when the AC voltage having a voltage level of the peak-to-peak voltage that is equal to or more than twice the discharge start voltage Vth of the image bearing member is applied to the charging means during the non-image forming period, are in a developing position of the developing means, a voltage applied to the developing means is fixed. 6. An image forming apparatus according to claim 2, wherein while the area on the image bearing member and an area on the image bearing member that is charged by the charging means when the AC voltage having a voltage level of the peak-to-peak voltage that is equal to or more than twice the discharge start voltage Vth of the image bearing member is applied to the charging means during the non-image forming period, are in a developing position of the developing means, a voltage applied to the developing means is OV. 7. An image forming apparatus according to claim 1, wherein the peak-to-peak voltage of the AC voltage which is applied to the charging means during the image forming period is equal to or more than twice the discharge start voltage Vth. 8. An image forming apparatus according to claim 1, wherein the non-image forming period is a preparatory rotation period of the image bearing member before executing an image formation. 9. An image forming apparatus according to claim 1, wherein the residual charge eliminating means is electrostatic latent image forming means for forming an electrostatic latent image on a surface of the image bearing member that is charged by the charging means. 10. An image forming apparatus according to claim 9, wherein the image bearing member is a photosensitive member, and wherein the residual charge eliminating means is exposure means for conducting exposure on the image bearing member in order to form the electrostatic latent image on the surface of the image bearing member that is charged by the charging means. 11. An image forming apparatus according to claim 1, wherein the residual charge eliminating means conducts charge elimination on the image bearing member on a downstream side of the charging means and an upstream side of the developing means with respect to a moving direction of the image bearing member. 12. An image forming apparatus according to claim 1, wherein the developing means also serves as cleaning means for collecting the developer remaining on a surface of the image bearing member. 13. An image forming apparatus according to claim 1, further comprising transferring means for transferring, onto a material to be transferred, an image that is formed on the image bearing member with the developer. 14. An image forming apparatus according to claim 13, wherein the transferring means also serves as cleaning means for collecting the developer remaining on a surface of the image bearing member. 15. An image forming apparatus according to claim 1, further comprising developer charging quantity control means, disposed further upstream than the charging means and further downstream than the transferring means with respect to the moving direction of the image bearing member, for applying a DC voltage in order to charge a residual developer remaining on the image bearing member to a normal polarity of the developer. 16. An image forming apparatus according to claim 1, wherein the charging means is brought into contact with the image bearing member to charge the image bearing member. 17. An image forming apparatus according to claim 1, wherein the charging means conducts charging by causing discharge between the charging means and the image bearing member. 18. An image forming apparatus according to claim 1, wherein the developing means performs developing by bringing the developer on the developing means into contact with the image bearing member.
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