IMAGE FORMING APPARATUS
First Claim
Patent Images
1. An image forming apparatus, comprising:
- a photoconductor on which an electrostatic latent image is formed;
a charging member configured to charge the photoconductor;
a developing member configured to develop the electrostatic latent image formed on the photoconductor with toner charged to predetermined polarity;
a transfer member configured to form a transfer portion together with the photoconductor and to transfer a toner image from the photoconductor to a recording material in the transfer portion;
a transfer power source configured to apply a voltage of polarity opposite to the predetermined polarity to the transfer member;
a guidance member provided upstream of the transfer portion in a conveyance direction of the recording material, and configured to guide the recording material in contact with a back surface of the conveyed recording material;
an auxiliary power source configured to apply a voltage of the opposite polarity to the guidance member;
a fixing unit configured to fix the toner image transferred from the photoconductor to the recording material; and
a control unit configured to control a potential difference between a surface potential of the photoconductor charged by the charging member and a potential of the guidance member,wherein the image forming apparatus is capable of performing duplex image formation by turning over the recording material in which the toner image is fixed to a first surface by the fixing unit, conveying the recording material to the transfer portion, and transferring the toner image from the photoconductor to a second surface, andwherein when performing the duplex image formation, the control unit controls a potential difference between a surface potential of the photoconductor charged by the charging member and a potential of the guidance member to be smaller during printing on the second surface than during printing on the first surface.
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Accused Products
Abstract
In a configuration in which a voltage of polarity opposite to charging polarity of toner is applied to a conveyance guide, controlling deposition of toner on the conveyance guide has been difficult. When performing duplex image formation, a potential difference between a surface potential of a photoconductive drum charged by a charging roller and a potential of the conveyance guide is smaller during printing on the second surface than during printing on the first surface.
5 Citations
12 Claims
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1. An image forming apparatus, comprising:
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a photoconductor on which an electrostatic latent image is formed; a charging member configured to charge the photoconductor; a developing member configured to develop the electrostatic latent image formed on the photoconductor with toner charged to predetermined polarity; a transfer member configured to form a transfer portion together with the photoconductor and to transfer a toner image from the photoconductor to a recording material in the transfer portion; a transfer power source configured to apply a voltage of polarity opposite to the predetermined polarity to the transfer member; a guidance member provided upstream of the transfer portion in a conveyance direction of the recording material, and configured to guide the recording material in contact with a back surface of the conveyed recording material; an auxiliary power source configured to apply a voltage of the opposite polarity to the guidance member; a fixing unit configured to fix the toner image transferred from the photoconductor to the recording material; and a control unit configured to control a potential difference between a surface potential of the photoconductor charged by the charging member and a potential of the guidance member, wherein the image forming apparatus is capable of performing duplex image formation by turning over the recording material in which the toner image is fixed to a first surface by the fixing unit, conveying the recording material to the transfer portion, and transferring the toner image from the photoconductor to a second surface, and wherein when performing the duplex image formation, the control unit controls a potential difference between a surface potential of the photoconductor charged by the charging member and a potential of the guidance member to be smaller during printing on the second surface than during printing on the first surface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification