Ricoh D014 Service Manual page 956

Process Control
Each f-theta lens has two layers. Because of this, it can correct both beams from the LD
units. Each WTL lens corrects for image distortion.
The polygon mirror turns at high speed. The laser beams are reflected from the polygon
mirror to a pair of mirrors (upper and lower), then to one more mirror and out to the drum
through the dust-shield glass. The polygon mirror has six faces.
The polygon mirror motor rotates at 33,307 (V-C2a) or 41,669 (V-C2b) rpm for full-color and
for black-and-white copying.
Because of its high rotation speed, the mirror continues to turn for about 3 minutes
after the machine is turned off. Allow enough time for the mirror to stop before you
start to remove the polygon motor.
What does MUSIC do?
MUSIC is the Mirror Unit for Skew and Interval Correction. Three MUSIC sensors above
the ITB read three MUSIC sensor patterns made by the machine on the ITB.
The machine uses the results to adjust:
The machine adjusts the start timing for the laser at the start of the main scan. This
adjusts the main scan. If skew is detected in the main scan direction, the machine
adjusts the laser timing and the angles of the 3rd mirrors (Y, M, and C only).
The speed of the drum motors to correct the intervals between the patterns. This
adjusts the sub scan.
If the vertical alignment of the patterns is not correct, or if the intervals are not correct, this
causes color registration errors.
The MUSIC adjustment is done for each color (Y, M, C, K).
D014/D015/D078/D079
CÓPIA NÃO CONTROLADA
6-52
CÓPIA NÃO CONTROLADA
SM