Image forming apparatus
AssigneeCanon Kabushiki Kaisha
InventorNaoki Kanno
Life of this patent
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Abstract
A control unit changes the polarity of a potential of an intermediate transfer member in a primary transfer portion by changing the polarity of voltage to be applied to a secondary transfer member, and applies first voltage in a first step of forming an image on a recording material by transferring a toner image. A detection device detects the presence/absence of the recording material at a timing when a rear end of the toner image reaches a second position which is upstream of a secondary transfer portion on a conveyance path of the toner image. The control unit determines a timing to switch the voltage to be applied to the secondary transfer member from the first voltage to second voltage having polarity opposite to that of the first voltage, based on the detection result by the detection device.
Claims13
An image forming apparatus, comprising:
- an image bearing member that bears a toner image;
- an intermediate transfer member onto which the toner image is primarily transferred from the image bearing member in a primary transfer portion that contacts the image bearing member;
- a secondary transfer member that constitutes, together with the intermediate transfer member, a secondary transfer portion, and secondarily transfers the toner image from the intermediate transfer member to a recording material in the secondary transfer portion;
- and
- a control unit that controls voltage to be applied to the secondary transfer member, wherein
- the control unit changes polarity of a potential of the intermediate transfer member in the primary transfer portion by changing polarity of the voltage to be applied to the secondary transfer member, applies a first voltage in a first step of forming an image on the recording material by transferring the toner image, and applies a second voltage having polarity opposite to that of the first voltage, in a second step, and
- in the transition from the first step to the second step, the control unit applies the second voltage to the secondary transfer member after the recording material and the toner image pass through the secondary transfer portion in the first step.
An image forming apparatus, comprising:
- an image bearing member that bears a toner image;
- an intermediate transfer member onto which the toner image is primarily transferred from the image bearing member in a primary transfer portion that contacts the image bearing member;
- a secondary transfer member that constitutes, together with the intermediate transfer member, a secondary transfer portion, and secondarily transfers the toner image from the intermediate transfer member to a recording material in the secondary transfer portion;
- a detection device that detects the presence/absence of a recording material at a first position which is upstream of the secondary transfer portion on a conveyance path of the recording material;
- and
- a control unit, wherein
- the control unit changes polarity of a potential of the intermediate transfer member in the primary transfer portion by changing polarity of voltage to be applied to the secondary transfer member, and applies a first voltage in a first step of forming an image on the recording material by transferring the toner image,
- the detection device detects the presence/absence of the recording material at a timing when a rear end of the toner image reaches a second position which is upstream of the secondary transfer portion on a conveyance path of the toner image, and
- based on the detection result by the detection device, the control unit determines a timing when the voltage to be applied to the secondary transfer member is switched from the first voltage to a second voltage having polarity opposite to that of the first voltage.
Dependencies are inferred from the claim text.