20 June 2005 LASER EXPOSURE
6-49
Detailed
Descriptions
6.6.2 AUTO POWER CONTROL (APC)
The LD driver on the LDDR drives the laser diode. Even if a constant electric
current is applied to the laser diode, the intensity of the output light changes with
the temperature. The intensity of the output decreases as the temperature
increases.
In order to keep the output level constant, the LDDR monitors the electrical current
passing through the photodiode (PD). Then it increases or decreases the current to
the laser diode as necessary, comparing it with the reference level. This auto
power control is done just after the machine is turned on and during printing while
the laser diode is active.
The reference levels are adjusted on the production line. Do not touch the variable
resistors on the LDDR in the field.
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