Ricoh FT4460, Service Manual, Page: 127 / 413

28 February 1989
10.3.1 Phase Control
In the phase control mode, the fusing lamp receives ac power constantly. The
amount of power is regulated by the width of the trigger pulse. The wider the
trigger pulse (C1), the more ac power the lamp receives (D1); therefore, the
temperature increases.
As the temperature rises, the LOW trigger pulse becomes narrower (C2) and
less power is applied to the lamp (D2); therefore, the heating effect
decreases.
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