Cr Motor Drive Circuit - Epson Stylus Color 400 Service Manual

2.2.2.8 CR Motor Drive Circuit

In the CR motor, the same LB1845(IC15) as the PF motor has is used. 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 performs Micro-step driving in the Stylus Color 400.
The figure below shows carriage motor drive circuit.
Figure 2-29. Connection Diagram CR 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
CR 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, 10 resistance which are connected to the output port(60 61pin,
63 70pin) of the gate array divide each current values of phase A and B in the CR motor.
The firmware possesses 16 different ways of current values individually 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
independently in the 26 and 17 pins. HIC is driven at the different standard voltage for each phase A and
B.
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. (Refer to figure 3-31 since it is same as the one of PF motor)
Rev.A
Chapter2 Operating Principles
2-31