Continuous recording medium friction-conveying mechanism in image forming apparatus

In an image forming apparatus comprising an image recording section including a photosensitive member on which a toner image is formed electrophotographically, a charging member for uniformly charging said photosensitive member, an optical member for forming an electrostatic latent image on said photosensitive member and a developing member for developing said latent image with toner to provide a toner image, recording medium conveying means for friction-conveying a continuous recording medium, and a transfer section for transferring said toner image to said recording medium,

• the improvement wherein said recording medium conveying means includes friction-conveying means for interposing therebetween and conveying said recording medium, which is provided downstream of said transfer section with respect to a recording medium conveying direction and comprises two rollers located on both edges of said recording medium which are outside an image transfer area and a roller disposed on a back side of a surface of said recording medium onto which an image is to be transferred, said two rollers each have pressing means by which said two rollers are pressed against said roller, and each of said pressing means has a pressing force of not less than .mu.d.multidot.Fq/(.mu.r.multidot.cos .theta.) relative to an attraction Fq between said recording medium and said photosensitive member, on an assumption that .theta. is an angle between a tangential direction of said photosensitive member and said recording medium conveying direction in said transfer section, .mu.d is a coefficient of friction between said recording medium and said photosensitive member, and .mu.r is a coefficient of friction between said recording medium and said roller.

An image forming apparatus comprising:

• a line sensor for detecting a position where a reference edge of a recording medium is present;
• line sensor output processing means which judges the position of said reference edge of said recording medium in cooperation with said line sensor to provide a recording medium reference edge position signal;
• a recording medium position correction means control device which finds a recording medium position correction value from an output of said line sensor output processing means to output a control signal;
• and
• recording medium position correction means disposed upstream of an image recording section with respect to a recording medium conveying direction for correcting the position of said reference edge on receiving said control signal from said recording medium position correcting means control device.

An image forming apparatus comprising:

• a line sensor disposed upstream of an image recording section with respect to a recording medium conveying direction for detecting a position where a reference edge of a recording medium is present;
• mask means adjustable in position for shielding a portion of a detection window of said line sensor;
• a recording medium position correction means control device which finds a recording medium position correction value from an output of said line sensor to output a control signal;
• and
• recording medium position correction means disposed upstream of the image recording section with respect to the recording medium conveying direction for correcting a position of said reference edge on receiving said control signal of said recording medium position correction means control device.