Pf (Pump) Motor Drive Circuit - Epson Stylus Color 400 Service Manual

EPSON Stylus Color 400 Service Manual

2.2.2.7 PF (Pump) Motor Drive Circuit

IC15(LB1845) is used for driving PF(Pump) motor. In the IC, Bi-pola drive PWM current control type
is performed, making it possible to provide stable current to each phase of motor.
Also, it makes possible to change over the reference voltage as drive current settings by making
3 combinations(100%, 66% and 33%), using 4 current setting ports(input). (Refer to 2.1.1.3 for motor
and details about sequence) However, firmware does not drive Micro-step in the Stylus Color 400.
The figure below shows connection diagram of PF(Pump) motor drive circuit.
Figure 2-27. Connection Diagram of PF(Pump) Motor Drive Circuit
Unlike using Uni-Pola drive, there is no cable for GND in the motor since Bi-Pola drive is performed in the
PF motor.(Refer to figure2-10 since carriage motor interior connection diagram has the same connection
as the PF motor's phase connection. This helps to understand the reason why the direction of
current is controlled freely in each phase by the combinations of high/low control signals.
The current control is performed by output port(46 49 pin) of E05B44(IC2), its outer resistance
circuit and driver IC(LB1845). First, firmware possesses 16 ways of current values as current table
out of combinations made by 5 resistance which are connected to the output ports(46 49 pin) in the
gate array. On the other hand, signals which are output by combination of these resistance's on/off
are input in the 26 and 17 pins. HIC is driven at the same standard voltage for each A and B phase.
Actual on/off control to send electricity through the motor is performed by the process that SEN1 and
SEN2 terminals (2 and 13 pin) detect the input signal from the gate array which is monitored by the
interior comparator, confirm the current that actually flew the phase as current value again and
perform the feed back to the on/off. The figure below shows relation between input signal to the
driver IC and motor control.
Figure 2-28.Motor Drive
2-30
Rev.A