Image recorder with microstep driven motor transport

Claim 1

An image forming apparatus for forming in series a plurality of images on a photosensitive film of the long roll type comprising: feeding means for feeding the film; discharging means for discharging an image-recorded film; transporting means interposed between said feeding means and said discharging means for transporting the film from said feeding means to said discharging means; a stepping motor for driving said transporting means; a microstep driver for controllably driving said stepping motor in a plurality of microsteps constituting one step unit of said stepping motor; imaging means for scanning and exposing the film being transported by said transporting means in a direction normal to a film transporting direction; wherein a pitch between adjacent images to be formed in series on the film is a multiple of an integer of a film transport distance covered by the single step unit of said stepping motor; said transporting means includes a platen roller driven and rotated by said stepping motor, said platen roller having a diameter predetermined to be of a multiple of an integer value of said film transport distance covered by one step unit of said stepping motor; and wherein said platen roller is mounted on a drive shaft of said stepping motor, said diameter: R of the platen roller, said pitch: P of the adjacent images to be formed in series on the film being represented by the following expression: R=(1/N)×(P/π)×(360/A) where N is an integer value and A is a step angle of said stepping motor.