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US 2003/0228166 A1Published application
Image forming apparatus
AssigneeCanon Kabushiki Kaisha
InventorsKen Nakagawa, Koichi Otaka
Life of this patent
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Abstract
An image forming apparatus including a movable image bearing member, a charging member disposed opposed to the image bearing member, a transfer member for transferring a toner image from the image bearing member onto a recording material, and potential control means far changing a potential gradient on the image bearing member at a position corresponding to an end of the recording material in a direction opposite from a charge polarity of the toner with respect to a direction opposite from a movement direction of the image bearing member.
Claims13
An image forming apparatus, comprising:
- a movable image bearing member,
- a charging member disposed opposed to said image bearing member,
- a transfer member for transferring a toner image from said image bearing member onto a recording material, and
- potential control means for changing a potential gradient on said image bearing member at a position corresponding to an end of the recording material in a direction opposite from a charge polarity of the toner with respect to a direction opposite from a movement direction of said image bearing member.
1 more element
An image forming apparatus, comprising:
- a movable image bearing member,
- a charging member disposed opposed to said image bearing member,
- a transfer member for transferring a toner image from said image bearing member onto a recording material,
- a power supply for applying a voltage to said transfer member, and
- potential control means for changing a potential gradient on said image bearing member at a position corresponding to an end of the recording material in a direction opposite from a charge polarity of the toner with respect to a direction opposite from a movement direction of said image bearing member,
- wherein said transfer member and said image bearing member form a transfer nip having a width W, and
- with respecto to a movement direction of the recording material, the following relationships are satisfied:
- V2−V1>V3−V4 when the toner has a negative charge polarity, and
- V2−V1<V3−V4 when the toner has a positive charge polarity,
- wherein V1 represents a voltage applied to said transfer member when a leading and of said recording material is located upstream from an upstream end of the transfer nip by W;
- V2 represents a voltage applied to said transfer member when the leading end of said recording material is located downstream from the upstream end of the transfer nip by W;
- V3 represents a voltage applied to said transfer member when a trailing end of said recording material is located upstream from a downstream end of the transfer nip by W;
- and V4 represents a voltage applied to said transfer member when the trailing end of said recording material is located downstream from the downstream end of the transfer nip by W.
10 more elements
An image forming apparatus, comprising:
- a movable image bearing member,
- a charging member disposed opposed to said image bearing member,
- a transfer member for transferring a toner image from said image bearing member onto a recording material,
- a power supply for applying a voltage to said transfer member, and
- potential control means for changing a potential gradient on said image bearing member at a position corresponding to an end of the recording material in a direction opposite from a charge polarity of the toner with respect to a direction opposite from a movement direction of said image bearing member,
- wherein said transfer member and said image bearing member form a transfer nip having a width W, and
- with respect to a movement direction of the recording material, the following relationships are satisfied:
- (V2−V1)/2W>(V4−V3)/2W>E3, and
- (V2−V1)/2W>|E3|,
- wherein V1 represents a voltage applied to said transfer member when a leading and of said recording material is located upstream from an upstream end of the transfer nip by W;
- V2 represents a voltage applied to said transfer member when the leading end of said recording material is located downstream from the upstream end of the transfer nip by W;
- V3 represents a voltage applied to said transfer member when a trailing end of said recording material is located upstream from a downstream end of the transfer nip by W;
- V4 represents a voltage applied to said transfer member when the trailing end of said recording material is located downstream from the downstream end of the transfer nip by W:
- and E3 represents a maximum of the potential gradient having a polarity opposite from the charge polarity of the toner.
11 more elements
Dependencies are inferred from the claim text.