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IMAGE STABILIZATION CONTROL CF5001 Ver.1.0 Sep. 2003
2-66
II UNIT EXPLANATION
14. IMAGE STABILIZATION CONTROL
14.1 Toner density control
The purpose of this control is to correct the reference value of toner density for each color against variable
factors of the image density such as environmental factors.
A. Explanation of the operation
The charging amount of toner changes depending on the environmental factors such as the temperature
and humidity.
And in proportion to the length of time since developer was last used, toner tends to be hard to get
charged.
The reference value of toner density is varied to correct these change in the charging amount of toner.
B. Timing of the operation
• When the environmental factors such as the temperature and/or humidity change.
• For each elapsed hour of the use of developer
14.2 Dmax control
The purpose of the Dmax control is to set the highest image density for each color to the reference level.
The Dmax control is carried out by the gamma sensor (PS11), drum motors /Y, /M, /C and /K (M14, M15,
M16 and M17), transfer belt motor (M18), 1st transfer pressure/release motor (M19) and the developing
motors /Y, /M, /C and /K (M20, M21, M22 and M23), and controlled by the printer control board (PRCB).
Related sensors include the temperature/humidity sensor (TEMP/HUM).
A. Explanation of the operation
With a patch image created on the transfer belt at the maximum exposure amount, each density is read by
the gamma sensor (PS11). This operation is repeated several times while changing a developing bias
value each time. The developing bias value obtained when the density reaches the reference level is
stored as an optimum developing bias value of the machine and developing is made at this developing bias
value.
B. Timing of the operation
• When the main switch (SW2) is turned on for the first time in 6 hours or more after it was turned off.
• When the job starts 6 hours or more after the SW2 has been turned on.
• Every 1,000 pages of output. However at the time of completion of the job, when the 1,000th page is
contained in the job.
• When the humidity has changed more than 30 % RH from the value measured at the last operation.