Color image forming apparatus

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. The pattern images of the respective colors are each generated by using a write start timing associated with the color as a reference, and the pattern to be provided by any of the recording devices is outputted on a downstream side of the belt relative to the pattern to be provided by another recording device which is located downstream of the first-mentioned recording device.