Form Of Electric Wave That Flows Into The Motor - Toshiba 1550 Service Manual

– Phase A excitation process –
1
øA becomes "L" level (øA is "H" level).
2
The reference voltage which is determined by a resistance type potential divider of R9, R10 and
R11 is applied to reverse input E for comparator IC1 and non-reverse input B is "L".
Therefore, IC1's output C becomes "L" level.
3 Due to 1 and 2 above, D of IC2 becomes "L" level and F1 becomes ON (conductive state).
4
Electric current flows to coil A from the +24 V power supply and increases gradually.
5 The terminal voltage of the electric current detection resistance R1 increases, and as the B voltage
gets higher than E voltage, C becomes "H" level and F1 becomes OFF.
6
As coils A and A are bipolar wound, the energy accumulated in coil A is induced into coil A and
discharged using coil A. In other words the electric current flows in the direction of DG
diode coil A.
7 The voltage accumulated in capacitor C1 decreases, and when it gets lower than E voltage, C
goes to "L" level and F1 comes ON again to increase the phase A winding electric current.
8
The above ON/OFF operation (constant current chopping) of the electric current for the motor is
repeated (refer to the diagram below).
When exciting phase A, phase øA becomes "L" level, while F2 becomes ON, and a similar operation is
conducted.
1550/1560 OPTICAL
I
OH

Form of electric wave that flows into the motor

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Mar. 1998 © TOSHIBA