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US 6,807,384 B2Granted
Image forming apparatus
AssigneeCanon Kabushiki Kaisha
InventorsKazuhiro Okubo, Masahide Kinoshita, Masaki Ojima, Motoki Adachi, Masao Uyama
Life of this patent
Estimating the term…
Abstract
To provide an image forming apparatus improving discharging of a developer from charge providing member for providing charge to the developer remaining on an image bearing member to the image bearing member, the developer is charged from the charge providing member to the image bearing member. When a developer discharging region of the image bearing member is disposed at a charging position, charging member is applied with a voltage having a direct current component of an absolute value equal to or smaller than an absolute value of voltage applied to the charge providing member without an alternating current component.
Claims70
An image forming apparatus comprising:
- an image bearing member;
- charging means for charging the image bearing member at a charging position, said charging means being capable of being applied with a voltage including a direct current component and an alternating current component;
- developing means for developing an electrostatic image formed at the image bearing member by a developer;
- transferring means for transferring an image of the developer formed at the image bearing member to an image receiving member;
- and
- charge providing means provided downstream from the transferring means and upstream from the charging means in a direction of moving the image bearing member for providing a charge to the developer remaining on the image bearing member, said charge providing means being applied with a voltage having a polarity the same as a normal charge polarity of the developer;
- wherein when a developer discharging region of the image bearing member at which the developer is discharged from the charge providing means to the image bearing member is disposed at the charging position, the charging means is applied with a voltage having a direct current component of an absolute value equal to or smaller than an absolute value of the voltage applied to the charge providing means without an alternating current component thereof.
4 more elements
An image forming apparatus comprising:
- an image bearing member;
- charging means for charging the image bearing member at a charging position;
- developing means for developing an electrostatic image formed at the image bearing member by a developer;
- transferring means for transferring an image of the developer formed on the image bearing member to an image receiving member;
- first charge providing means provided downstream from the transferring means and upstream from the charging means in a direction of moving the image bearing member for providing a charge to the developer remaining on the image bearing member, said first charge providing means being applied with a voltage having a polarity reverse to a normal charge polarity of the developer;
- and
- second charge providing means provided downstream from the first charge providing means and upstream from the charging means in the direction of moving the image bearing member for providing a charge to the developer remaining on the image bearing member, said second charge providing means being applied with a voltage having a polarity the same as a normal charge polarity of the developer;
- wherein a surface potential of a region being to constitute a developer discharging region of the image bearing member at which the developer is discharged from the first and the second charge providing means to the image bearing member is set to substantially 0V.
5 more elements
An image forming apparatus comprising:
- an image bearing member;
- charging means for charging the image bearing member at a charging position, said charging means being capable of being applied with a voltage including a direct current component and an alternating current component;
- developing means for developing an electrostatic image formed at the image bearing member by a developer;
- transferring means for transferring an image of the developer formed at the image bearing member to an image receiving member;
- first charge providing means provided downstream from the transferring means and upstream from the charging means in a direction of moving the image bearing member for providing a charge to the developer remaining on the image bearing member, said first charge providing means being applied with a voltage having a polarity reverse to a normal charge polarity of the developer;
- and
- second charge providing means provided downstream from the first charge providing means and upstream from the charging means in the direction of moving the image bearing member for providing a charge to the developer remaining on the image bearing member, said second charge providing means being applied with a voltage having a polarity the same as the normal charge polarity of the developer;
- wherein when a region being to constitute a developer discharging region of the image bearing member discharged with the developer from the first and the second charge providing means to the image bearing member is disposed at the charging position, the charging means is applied with a voltage including an alternating current component and a direct current component an absolute value of which is smaller than absolute values of voltages supplied to the first and the second charge providing means.
5 more elements
An image forming apparatus comprising:
- an image bearing member:
- charging means for charging an image bearing member at a charging position;
- developing means for developing an electrostatic image formed at the image bearing member by a developer;
- transferring means for transferring an image of the developer formed at the image bearing member to an image receiving member;
- first charge providing means provided downstream from the transferring means and upstream from the charging means in a direction of moving the image bearing member for providing a charge to the developer remaining on the image bearing member, said first charge providing means being applied with a voltage having a polarity reverse to a normal charge polarity of the developer;
- and
- second charge providing means provided downstream from the first charge providing means and upstream from the charging means in the direction of moving the image bearing member for providing a charge to the developer remaining on the image bearing member, said second charge providing means being applied with a voltage having a polarity the same as the normal charge polarity of the developer;
- and
- wherein an ON/OFF operation is repeated to respective voltages applied to the first and the second charge providing means such that a first developer discharging region of the image bearing member formed with an electric field for discharging the developer from the first charge providing means to the image bearing member and a second developer discharging region of the image bearing member formed with an electric field for discharging the developer from the second charge providing means to the image bearing member differ from each other.
6 more elements
An image forming apparatus comprising:
- an image bearing member;
- charging means for charging the image bearing member at a charging position, said charging means being capable of being applied with a voltage including a direct current component and an alternating current component;
- developing means for developing an electrostatic image formed at the image bearing member by a developer;
- transferring means for transferring an image of the developer formed at the image bearing member to an image receiving member;
- first charge applying means provided downstream from the transferring means and upstream from the charging means in a direction of moving the image bearing member for providing a charge to the developer remaining on the image bearing member, said first charge providing means being applied with a voltage having a polarity reverse to a normal charge polarity of the developer;
- and
- second charge providing means provided downstream from the first charge providing means and upstream from the charging means in the direction of moving the image bearing member for providing a charge to the developer remaining on the image bearing member, said second charge providing means being applied with a voltage having a polarity the same as the normal charge polarity of the developer;
- wherein a surface potential of a region being to constitute a developer discharging region of the image bearing member discharged with the developer from the first and the second charge providing means to the image bearing member is set to substantially 0V;
- wherein when the developer is discharged from the first and the second charge providing means to the developer discharging region, the first and the second charge providing means are applied with a voltage such that the surface potential of the developer discharging region remains unchanged;
- and
- wherein when the developer discharging region is disposed at the charging position, the charging means is applied with a voltage including a direct current component of substantially 0V without an alternating current component.
8 more elements
Dependencies are inferred from the claim text.