Fig. 3-33; Drum Unit; Toner Cartridge- Page 67

CHAPTER 3  THEORY OF OPERATION

3-25

  2.3.2

Toner sensor

Detects if there is toner in the toner cartridge.  The toner sensor at the left side emits light
through the window on the left side of the toner cartridge, then the toner sensor at the right
side receives it when the toner is low.  They also detect whether or not the drum unit is
installed.  (The toner cartridge is installed in the drum unit.)

Fig. 3-33

2.4

Drum Unit

  2.4.1

Photosensitive drum

Generates the latent electrostatic image and develops the image on the drum surface.

  2.4.2

Primary charger

Forms a uniform charge on the drum surface.

(1) Corona 

wire

Generates the ion charge on the drum.

(2) Grid

Spreads the ion charge evenly over the drum surface.

  2.4.3

Transfer roller

Transfers the toner image to the paper from the drum surface.

  2.4.4

Cleaner

Removes the paper dust or dirt on the surface of the photosensitive drum.

2.5

Toner Cartridge

Develops the electrostatic latent image on the photosensitive drum with toner and forms the
visible image.

Toner sensor

(light emission)

Toner sensor
(light reception)