Patent ID: 7539453

Claim:
A printer for forming a toner image on a recording medium, comprising: a first printing unit for forming a toner image on a first side of said recording medium and second, third, and fourth printing units, respective ones of said second, third and fourth printing units forming a toner image on said first side of said recording medium; wherein said first printing unit has a first rotation member arranged on said first side of said recording medium and a first transfer unit arranged opposite to said first rotation member for transferring a toner mage onto said first side of said recording medium at a first transfer position; respective ones of said second, third, and fourth printing units having respective ones of second, third, and fourth rotation members arranged on said first side of said recording medium and respective second, third and fourth transfer units arranged opposite to respective ones of said second rotation member for transferring a toner image onto said first side of said recording medium at respective ones of second, third, and fourth transfer position; wherein a first straight line connecting a central point of said first rotation member and said first transfer position is inclined to a perpendicular direction in relation to a second straight line connecting said first transfer position and said second transfer position, and when said recording medium is conveyed between said first transfer position and said second transfer position along said second straight line, said recording medium is conveyed in a wrapping width of W with each rotation member, and said wrapping width W is 5 mm≦W≦25 mm, said wrapping width W being obtained by selecting positions of two conveying rollers for conveying the recording medium respectively installed above and below the first, second, third and fourth printing units and a position of one single wrapping roller for wrapping the recording medium installed between second and third printing units, wherein wrapping the recording medium around the first, second, third, and fourth rotation member is obtained by the one single wrapping roller and the two conveying rollers without requiring any other roller for said wrapping.