An ink jet recording apparatus provides a plurality of recording heads arranged in a scanning direction, each having a plurality of nozzles arranged substantially perpendicular to the scanning direction, and records by discharging ink from the nozzles onto a recording medium by application of drive signals. A first and a second layshaft are arranged to define a second and a third axis of rotation, respectively. In addition, provided is an apparatus and method for correcting gain and offset of the thermal images to be identical to each other and ensuring uniformity by using a process module separately from two thermal imaging cameras. The programmable element is capable of comparing the external reference signal with the rotational speed of the rotor and, consequently, controls the rotor circuitry based upon the comparison of the external reference signal and the rotational speed of the rotor.