Two-sided image forming apparatus

A two-sided image forming apparatus comprising:

• (a) an image carrying member;
• (b) a toner image forming means for forming a toner image on the image carrying member;
• (c) a belt-shaped intermediate transfer body for conveying a transfer material, having a volume resistivity R (Ω·cm) wherein the following expression is satisfied,
• 109≦R<1012;
• (d) a primary transferring means for transferring the toner image on the image carrying member onto the intermediate transfer body or a front face of the transfer material;
• and
• (e) a secondary transferring means for transferring the toner image on the intermediate transfer body onto a rear face of the transfer material,
• wherein the following expression is satisfied,
• 0.12≦I(2)/V≦0.98
• where I(2) (μA) represents an absolute value of a secondary transfer current when the toner image on the intermediate transfer body is transferred to the rear face of the transfer material by the secondary transferring means, and V (mm/sec) represents a moving velocity of the intermediate transfer body.

A two-sided image forming apparatus comprising:

• (a) a first image carrying member;
• (b) a first image forming means for forming a toner image on the first image carrying means;
• (c) a second image carrying member;
• (d) a second image forming means for forming a toner image on the second image carrying means;
• (e) a belt-shaped intermediate transfer body for conveying a transfer material, having a volume resistivity R (Ω·cm) wherein the following expression is satisfied,
• 109≦R<1012;
• (f) a first primary transferring means for transferring the toner image on the first image carrying member onto the intermediate transfer body;
• (g) a second primary transferring means for transferring the toner image on the second image carrying member onto a front face of the transfer material;
• and
• (h) a secondary transferring means for the toner image on the intermediate transfer body onto a rear face of the transfer material,
• wherein the following expressions are satisfied,
• 0.2≦I2(1B)/V≦0.7
• and
• 0.6×I2(1B)≦I(2)≦1.4×I2(1B)
• where I2(1B) (μA) represents an absolute value of a second primary transfer current when the toner image on the second image carrying member is transferred to the front face of the transfer material by the second primary transferring means, I(2) (μA) represents an absolute value of a secondary transfer current when the toner image on the intermediate transfer body is transferred to the rear face of the transfer material by the secondary transferring means, and V (mm/sec) represents a moving velocity of the intermediate transfer body.

A two-sided image forming apparatus comprising:

• (a) a first image carrying member;
• (b) a first toner image forming means for forming a toner image on the first image carrying member;
• (c) a second image carrying member;
• (d) a second toner image forming means for forming a toner image on the second image carrying means;
• (e) a belt-shaped intermediate transfer body for conveying a transfer material, having a volume resistivity R (Ω·cm) wherein the following expression is satisfied,
• 109≦R<1012;
• (f) a first primary transferring means for transferring the toner image on the first image carrying member onto the intermediate transfer body;
• (g) a second primary transferring means for transferring the toner image on the second image carrying member onto a front face of the transfer material;
• and
• (h) a secondary transferring means for transferring the toner image on the intermediate transfer body onto a rear face of the transfer material,
• wherein the following expression is satisfied,
• 0.12≦I(2)/V≦0.98
• where I(2) (μA) represents an absolute value of a secondary transfer current when the toner image on the intermediate transfer body is transferred to the rear face of the transfer material by the secondary transferring means, and V (mm/sec) represents a moving velocity of the intermediate transfer body.

A two-sided image forming apparatus comprising:

• (a) an image carrying member;
• (b) a toner image forming means for forming a toner image on the image carrying member;
• (c) a belt-shaped intermediate transfer body for conveying a transfer material;
• (d) a primary transferring means for transferring the toner image on the image carrying member onto the intermediate transfer body or a front face of the transfer material;
• (e) a secondary transferring means for transferring the toner image on the intermediate transfer body onto a rear face of the transfer material;
• and
• (f) a fixing means for interposing the transfer material to convey and for fixing the toner image transferred on both faces of the transfer material, the fixing means comprising a pair of rotatable fixing members,
• wherein an electric voltage of the same polarity as the transfer material on the both faces of which the toner images are transferred is applied to the fixing member to be in contact with the front face of the transfer material.