Kyocera Mita KM-4530 Service Manual page 302

2BC/D
Drum
1 Laser diodes: Generate the laser beams that form the latent image on the drum.
2 Collimator lenses: Collimate the diffused laser beams emitted from the laser diodes into cylindrical beams.
3 Beam splitter: Refracts the laser beam emitted from one of the laser diodes so that it becomes parallel to the other
laser beam, and sends those two beams to lens 1.
4 Polygon mirror: 6-faced mirror that rotates at approximately 34251.969 rpm. Each face reflects the laser beams
toward the drum in the horizontal (main) scan direction. The motion of the beams across the drum forms one scan
line.
5 Lenses 1, 2, 3 and 4: Maintain scanning speed across the drum and beam diameters constant. These lenses also
correct the vertical alignment of the polygon mirror so that the focal plane of the laser beams are always on the drum.
6 Object mirror: Reflects the laser beams onto the drum surface.
7 BD sensor mirror: Directs a laser beam to the BD sensor to generate the horizontal sync signal.
8 Cylindrical correcting lens: Corrects for the deviation of the laser beam reflected by the BD sensor mirror.
9 BD sensor: Detects the laser beam reflected by BD sensor mirror, and sends the detection signal to the main PCB
(MPCB). The main PCB (MPCB) uses this signal to determine the horizontal scanning signal timing.
0 Glass dust filter: Prevents dust from entering the unit.
The dimensions of the laser beam are as shown in Figure 2-1-22.
Scanning in the main direction is provided by the rotating polygon mirror, while scanning in the auxiliary direction is
provided by the rotating drum, forming a static latent image on the drum.
The static latent image of the letter "A", for example, is formed on the drum surface as shown in Figure 2-1-23. Electrical
charge is dissipated on the area of the drum surface irradiated by the laser.
The focal point of the laser beam is moved line by line, and adjacent lines slightly overlap each other.
µ
65 m
Figure 2-1-22
2-1-20
Figure 2-1-21 Laser scanner unit (2)
µ
70 m
Main
scanning
direction
Auxilary
scanning
direction
: laser beam is on
Figure 2-1-23