HP Color LaserJet CM4730 Service Manual - Page 202

COLOR MISREGISTRATION signal LED DRIVE signal DC controller PCB Color misregistration pattern image ETB Color misregistration sensor (R) Pattern image Color misregistration sensor (L) Light emitter (LED) Light receiver (PD) COLOR MISREGISTRATION signal Figure 4-31 Color misregistration detection The DC controller notifies the formatter of each error when the following errors are found during the color misregistration detection. The initial value is reset to the new color misregistration correction value whenever an error occurs. ● Color misregistration sensor abnormality warning: The light receiver does not receive light at all. ● Color misregistration measurement out of range warning: The measurement value is out of specified range. Image stabilization control This controls the variation of the image density caused by an environmental change or deterioration of the photosensitive drum, toner, etc. There are three types of image stabilization control. These controls operate when necessary. ● Environmental change control. The environment condition sensor controls the bias according to the environment conditions. ● Image density control (D-max). The color misregistration sensor (PS12) calibrates the bias value when the image density is at max. ● Image halftone control (D-half). The color misregistration sensor (PS12) calibrates the halftone data in the formatter. 182 Chapter 4 Theory of operation ENWW