COPYRIGHT © 1999 CANON INC. CANON 660/2100 REV.0 FEB. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)V. IMAGE STABILIZATION CORRECTION CONTROLThe machine executes image stabilization correction control to suppress fluctuationsin image density caused by changes in the site environment, changes in the photosensi-tive drum over time, and changes in toner. The control mechanism consists of environ-mental changes correction control, image density correction control, and image gradationcorrection control.A. Environmental Changes Correction ControlThe DC controller PCB identifies the condition of the site based on the machine inter-nal temperature and humidity detection signals from the temperature and humidity sen-sor on the temperature/humidity sensor PCB, and performs the following to ensure opti-mum images:• Determines whether to turn on or off the separation static eliminating bias.• Determines the target density for image density correction control.The copier executes environmental changes correction control at the following timing:• Before starting image density correction control.• Every 30 min after the end of image density correction control.B. Image Density Correction Control (maximum density con-trol)The DC controller PCB draws a density detection pattern for each color on the inter-mediate transfer drum to suit the environmental conditions whose data is obtained as aresult of environmental changes correction control.Then, it checks the density detection pattern using the density sensor to determinethe developing bias and the primary charging bias most likely to ensure stable density forthe color in question.Image density correction control is performed for the following:• At the end of environmental changes correction control at power-on.• At the end of making a specific number of prints.• After returning from power save mode.• When a toner cartridge has been taken out and put back in. (Note 1)• When the drum cartridge has been replaced. (Note 2)• When appreciable changes occurred in the environment as part of environmentalchanges control.CHAPTER 4 IMAGE FORMATION SYSTEM4-21Download free service manual at http://printer1.blogspot.com
