E. Controlling the Blanking Exposure Lamp (LED)1. OutlineThe blanking exposure lamp is a LED array consisting of 134 LEDs.All 134 LEDs turns on when the blanking exposure lamp activation signal (BLKON)generated by the DC controller goes ‘0’ while the drum is rotating but the original is notexposed, potential control is not on, and AE mode is off so as to prevent adhesion ofexcess toner to the photosensitive drum.The six LEDs at the rear and the six LEDs at the front are turned on at all times.2. Controlling the Activation in Reduce ModeWhen the original is exposed in Reduce mode, as many LEDs (rear) as suited to theselected reproduction ratio are turned on to remove the image in the non-image area.Some LEDs at the front are also turned on at this time to suit the size of the copypaper.3. Controlling the Activation in Direct ModeWhen the original is exposed in Direct mode, as many LEDs as suited at both frontand rear are turned on to remove the image in the non-image area.When a default-size copy paper is used to make a default-size copy or in Directmode, a non-image width (Table 4-105) is created at both rear and front (standard frameerasing).The non-image width may be set to 0 mm in service mode.4. Controlling the Activation in Sheet Frame Erase ModeLEDs are turned on so as to prevent adhesion of toner in widths of about 7 mmaround the edges of the copy paper in sheet frame erase mode. The width remains thesame regardless of the selected reproduction ratio.Reference:When using the multifeeder, you may specify a copy paper size or ‘free’: if youspecify a size, frame erasing will be executed to suit the size; if you select ‘free’, onthe other hand, frame erasing will be executed using the maximum size (297 × 432mm).COPYRIGHT © 1997 CANON INC. CANON NP6350/NP6251 REV. 0 JULY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)CHAPTER 4 IMAGE FORMATION SYSTEM4-19
