3. Controlling the Scanner Motor Brakea. OutlineThe scanner motor is controlled by a braking mechanism so that the scanner may bestopped accurately at home position when it is moved in reverse, free from changes inthe braking characteristics caused by changes in temperature.b. Controlling the Braking MechanismThe distance traveled by the scanner between when braking is applied and when thespeed drops below a specific value is monitored to find out the degree of braking usedto adjust the breaking mechanism (time). The speed of the scanner is monitored in rela-tion to the intervals of scanner motor F signal (M3FG), and the distance of travel is mon-itored in relation to the number of FG signals.• braking too weak (distance after braking is long)Ýcorrect to increase braking• braking too strong (distance after braking is short)Ýcorrect to decrease brakingThe data used to correct braking is not backed up, and therefore is lost when thepower is turned off. A sampling scan is made during the warm-up period to collect brak-ing correction data in preparation for copying operation. (At this time, the degree of brak-ing is made maximum.)Table 3-302 Sampling Scan TimingThe scanning operation normally executed during the warm-up period is prohibited ifthe RDF remains open to ensure safety for the service person. Instead, the degree ofbraking is sampled during the first copying run, by making the degree of braking maxi-mum.A sample scan is made if the copyboard cover open/closed detecting lever ispressed by a tool or the copyboard cover pen/closed sensor (PS5) is blocked. Toavoid injuries, do not service under such conditions.CHAPTER 3 EXPOSURE SYSTEM3-8 COPYRIGHT © 1997 CANON INC. CANON NP6560/NP6360/NP6260 REV. 0 NOV. 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)Caution:Fixing assembly temperature is lessthan 100°C at time of power-onFixing assembly temperature is100°C or more at time of power-onAfter initializing the lens unitAfter end of initial rotation
