Image forming apparatus with cleaning mechanism for charging electrode

An image forming apparatus, comprising:

• a movable image bearing member;
• means for electrically charging said image bearing member to a first potential;
• latent image forming means for forming a latent image with use of said charging means;
• developing means for developing the latent image formed by said latent image forming means with toner electrically charged to a polarity the same as a polarity of the first potential;
• image transfer means contactable to a back side of a transfer material at a transfer position to transfer a toner image provided by said developing means from said image bearing member to the transfer material;
• voltage application means for applying a voltage to said image transfer means, said voltage application means applying a voltage having a polarity the same as that of the toner to said image transfer means during non-transfer action by said transfer means;
• and
• means for providing a second potential for that portion of said image bearing member which is to be presented to the transfer position during said voltage application by said voltage application means, wherein the second potential is different from the first potential,
• wherein said different second potential is lower than an absolute value of the first potential,
• wherein said different potential providing means provides a potential having an absolute value for said portion of said image bearing member, the absolute value being smaller than an absolute value of a voltage applied to said image transfer means by said voltage applying means during non-transfer action.

An image forming apparatus, comprising:

• a movable image bearing member;
• charging means for electrically charging said image bearing member to a first potential;
• latent image forming means for forming a latent image on said image bearing member with use of said charging means;
• developing means for developing the latent image formed by said latent image forming means with toner;
• image transfer means contactable to a back side a transfer material at a transfer position to transfer a toner image provided by said developing means from said image bearing member to the transfer material;
• potential application means for applying to said image transfer means a second potential during non-transfer action of said image transfer means to form an electric field to transfer the toner from said transfer means to said image bearing member, and a third potential during transfer action of the image transfer means;
• and
• means for providing said image bearing member with such a potential that a difference between the second potential and a potential of that portion of said image bearing member which is to be presented to the transfer position during application of the second potential, is larger than a potential difference between the second potential and the first potential and the potential of that portion of the image bearing member is different from the first potential and is remote from the first potential in a direction opposite from a polarity of the electric charge of the toner.

An image forming apparatus, comprising:

• a movable image bearing member for bearing a latent image and a developed image from the latent image;
• a charging electrode contactable to said image bearing member at a charging position;
• potential application means for applying a voltage to said electrode, said potential application means applying to said electrode a first potential when an image area of said image bearing member is in said charging position, and a second potential when a non-image area of said image bearing member is in said charging position;
• and
• means for providing said image bearing member with such a potential that a potential difference between the second potential and a potential of that portion of said image bearing member which is to be presented to the charging position during application of the second potential, is larger than a potential difference between the second potential and a high potential of the latent image constituted by the high potential and a low potential, wherein by the first mentioned potential difference, an electric field effective to transfer toner from said charging electrode to said image bearing member is formed.

An image forming apparatus, comprising:

• a movable image bearing member;
• charging means for electrically charging said image bearing member to a first potential;
• latent image forming means for forming a latent image on said image bearing member with use of said charging means;
• developing means for developing the latent image formed by said latent image forming means with toner;
• image transfer means contactable to a back side of a transfer material at a transfer position to transfer a toner image provided by said developing means from said image bearing member to the transfer material;
• potential application means for applying to said image transfer means a second potential during non-transfer action of said image transfer means to form an electric field to transfer the toner from said transfer means to said image bearing member, and a third potential during transfer action;
• means for providing a fourth potential for that portion of said image bearing member which is to be presented to the transfer position during the second potential application by said potential application means, wherein an absolute value of the fourth potential is lower than that of the first potential;
• wherein said transfer means is press-contacted to said image bearing member with a pressure not more than 300 g/cm.sup.2.

An image forming apparatus, comprising:

• a movable image bearing member;
• charging means for electrically charging said image bearing member to a first potential;
• latent image forming means for forming a latent image on said image bearing member with use of said charging means;
• developing means for developing the latent image formed by said latent image forming means with toner;
• image transfer means contactable to a back side of a transfer material at a transfer position to transfer a toner image provided by said developing means from said image bearing member to the transfer material;
• potential application means for applying to said image transfer means a second potential during non-transfer action of said image transfer means to form an electric field to transfer the toner from said transfer means to said image bearing member, and a third potential during transfer action;
• means for providing a fourth potential for that portion of said image bearing member which is to be presented to the transfer position during the second potential application by said potential application means, wherein the fourth potential is different from the first potential;
• wherein said transfer means has a rubber hardness of not greater than 30 degrees (JISA).

An image forming apparatus, comprising:

• a movable image bearing member;
• image forming means for forming a toner image on said image bearing member;
• image transfer means contactable to a back side of an image transfer material at a transfer position to transfer the toner image from said image bearing member to the transfer material;
• electric field forming means for forming an electric field between said image bearing member and said transfer means, said electric field forming means forming a first electric field effective to transfer the toner from said transfer means to said image bearing member and a second electric field bearing a direction opposite to that of the first electric field, when the transfer material is not present at the transfer position.

An image forming apparatus, comprising:

• a movable image bearing member;
• means for electrically charging said image bearing member to a first potential;
• toner image forming means for forming a toner image on said image bearing member;
• image transfer means contactable to a back side of a transfer material at a transfer position to transfer the toner image from said image bearing member to the transfer material;
• potential application means for applying a second potential to said transfer means when the transfer material is not at the transfer position;
• potential providing means for providing a third potential for that portion of said image bearing member which is to be presented to the transfer position during the second potential application by said potential applying means, the third potential is different from the first potential and is remote from the first potential in a direction opposite from a polarity of the electric charge of the toner.

An image forming apparatus, comprising:

• a movable image bearing member;
• means for electrically charging said image bearing member to a first potential;
• toner image forming means for forming a toner image on said image bearing member;
• image transfer means contactable to a back side of a transfer material at a transfer position to transfer the toner image from said image bearing member to the transfer material;
• potential application means for applying a second potential to said transfer means when the transfer material is not at the transfer position;
• potential providing means for providing a third potential for that portion of said image bearing member which is to be presented to the transfer position during the second potential application by said potential applying means, wherein a first electric field is formed during potential application by said potential applying means at the transfer position by the second and third potentials, the first electric field being effective to transfer the toner from said transfer means to said image bearing member, and wherein a second electric field is formed at the transfer position by the first and second potential, and wherein said first electric field is more effective to transfer the toner from said transfer means to said image bearing member than said second electric field.