Canon iR C3380 series, Service Manual

Page: 231 / 610

Chapter 7
7-21
7.3.8 ARCDAT Control
0013-8492
/ / / / iR C3380i / iR C3380 / iR C2880i / iR C2880
The machine performs abridged D-half control to attain ideal gradation characteristics and to reduce downtime (by the main controller).
1. Start-Up Timing
- when the power is turned on
- during post-rotation executed every 25 prints (*1)
- during return from sleep
*1: When printing an original with an image ratio of 25% or less.
2. Particulars of Control
In the presence of a specific condition, the DC controller forms a patch pattern of each color (Y, M, C, Bk) on the ITB (a single pattern for each color, a total of 4
patterns). Thereafter, the DC controller measures the patch pattern using the patch image sensor (UN14), and sends the result back to the main controller, which in
turn compares it against the abridged D-half reference data backed up in memory and uses the difference as the offset value for D-half.
F-7-28
[1] Patch image data
[2] Density data
[3] Abridged D-half control
[4] Video data
UN16: patch image sensor
3. Flow of Operation
Y
M
C
Bk
D-CON
UN16
ITB
[1]
[3]
Laser Scanner
unit
[4]
M-CON
[2]