Controlling The Blanking Exposure Lamp (Led); Outline; Controlling The Activation In Reduce Mode; Controlling The Activation In Direct Mode - Canon NP6251 Service Manual

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E. Controlling the Blanking Exposure Lamp (LED)

The 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 not

exposed, potential control is not on, and AE mode is off so as to prevent adhesion of

excess toner to the photosensitive drum.

The six LEDs at the rear and the six LEDs at the front are turned on at all times.

When the original is exposed in Reduce mode, as many LEDs (rear) as suited to the

selected 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 copy

When the original is exposed in Direct mode, as many LEDs as suited at both front

and 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 Direct

mode, a non-image width (Table 4-105) is created at both rear and front (standard frame

The non-image width may be set to 0 mm in service mode.

4. Controlling the Activation in Sheet Frame Erase Mode

LEDs are turned on so as to prevent adhesion of toner in widths of about 7 mm

around the edges of the copy paper in sheet frame erase mode. The width remains the

same regardless of the selected reproduction ratio.

When using the multifeeder, you may specify a copy paper size or 'free': if you

specify a size, frame erasing will be executed to suit the size; if you select 'free', on

the other hand, frame erasing will be executed using the maximum size (297

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CANON NP6350/NP6251 REV. 0 JULY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)

CHAPTER 4 IMAGE FORMATION SYSTEM

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