Service manual

EPSON Stylus Color 400 Service Manual
Rev.A
2-3
0
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.
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.
+42V
Figure 2-27. Connection Diagram of PF(Pump) Motor Drive Circuit
E05B44(IC2)
Gate Array
+5V
+42V
RS
R1
R2 R3
R4
Ra
Rb
UDN2917(IC14,IC15)
In case of PM motor,
same reference voltage
is input to UDN2917 for
both phase A and B, but
differet reference voltage
is set individually for
phase A and B, in case of
CR motor.
Note:
It varies load resistance
by the control signal and
changes the ratio of partial
pressure.
If feeds back the current
that actually flew in the
coil to the comparator.
Figure 2-28.Motor Drive