Epson Stylus Photo 950, Service Manual

Page: 28 / 191

EPSON Stylus PHOTO 950 Revision A
OPERATING PRINCIPLES Printer Mechanism 28
2.2.2 Carriage Mechanism
The carriage mechanism consists of components such as a carriage motor (CR motor),
carriage guide shaft, platen gap adjustment mechanism, parallelism adjustment
mechanism and a carriage lock mechanism.
2.2.2.1 Carriage Motor (CR Motor)
The carriage mechanism used in this printer uses a DC motor as the drive source, in the
same way as in previous models. The specifications for the DC motor used to drive the
carriage mechanism are shown below.
The CR motor in previous models was a stepping motor, and the position of the
carriage unit was controlled by means of open loop control. However, this printer
employs closed loop control via the DC motor and a linear encoder to control the
carriage speed and position in order to provide the same stable printing quality as the
EPSON Stylus PHOTO 890.
At the same time, the CR motor is also used to generate the basic signal (PTS signal)
that is used to regulate the ink ejection timing (See "CR Motor Driver Circuit" on page
50 for details on the CR motor control circuit.)
Figure 2-3. Carriage Mechanism (TOP VIEW)
During printing, the carriage unit is moved within the printing area by the CR motor
along the carriage guide shaft of the printer mechanism.
Table 2-2. Carriage Motor Specification
Items Specifications
Type
DC motor
Drive Voltage
+42 +/- 5 % (DRV IC voltage)
Coil Resistance
23.0
Ω
+/- 25 % (per phase at 25 degree)
Inductance
24.0 mH +/- 25% (1KH 1VmA)
Drive Method
PWM drive, Constant current chopping
Driver IC
A3958
Parallelism
adjustment
bushing
CR guide
shaft
CR motor
Platen surface Carriage
unit
CR guide shaft
Linear scale