| 摘要 |
PURPOSE:To attain an accurate image density control by precisely detecting the density of a pattern image and the density of a surface. CONSTITUTION:A reflection type photosensor PSN detects the quantity of reflected light obtained by irradiating the pattern image on a charged body and the quantity of reflected light obtained by irradiating a no-image area on the charged body and the supplementation of toner to a developing unit is controlled according to the correlation between both the quantities of reflected light. At this time, the pattern image is formed in specific image formation conditions wherein the output of the sensor PSN becomes the output of an area where variation in the detected value with the density is high. Consequently, the sensor sensitivity is high and the pattern image density can accurately be detected. The no-image area corresponding to the surface part is formed in the specific image formation conditions which are smaller in surface staining than that in the image formation conditions, so neither carrier sticking nor excessive surface staining is generated. |
