Abstract: An image forming apparatus of the type producing a single composite color image on a paper which is transported by a belt by transferring image components of different colors to the paper in register with each other. The apparatus reduces with a simple construction the positional deviation of the image components which occurs in an intended direction of paper transport. Recording devices individually adapted for black, cyan, magenta and yellow are arranged side by side. Pattern images for measurement each being associated with a respective one of those colors are formed on the belt. A timing at which each of the pattern images arrives is sensed and counted. The count is compared with a reference value to calculate an amount of deviation. Write start timing signals each being associated with a particular color are generated which are individually variable on the basis of the deviation calculated.

Abstract: A paper feeder is disclosed which has a plurality of trays arranged one above another and a paper feed unit movable up and down to one of the trays selected. To control paper transport speed, a paper sensor is actuated prior to a level sensor during movement of the paper feed unit to a paper feed position, and a paper feed unit drive motor begins to be decelerated in response to an "on" signal of the paper sensor. The amount of papers remaining in any of the trays is detected by counting drive pulses applied to a pulse motor, which is adapted to drive the paper feed unit. After a power source has been turned on, the amounts of remaining papers in all the trays are detected and displayed prior to a copying operation.