Epson CX3810 - Stylus Color Inkjet, Service Manual

Page: 39 / 171

EPSON Stylus CX3700/CX3800/CX3805/CX3810/DX3800/DX3850 Revision A
OPERATING PRINCIPLES Printer Mechanism 39
2.2.3 Carriage Mechanism
The Carriage Mechanism consists of Carriage Unit (including the Print Head, CR
Encoder Board and PW Sensor), CR Motor, Timing Belt and CR Scale etc.
Following figure shows you each component for the CR Mechanism.
2.2.3.1 Carriage Mechanism
The following DC motor controls the CR Mechanism on this printer.
Close loop control based on the CR Motor (DC Motor) and CR Encoder has
advantages in stabilized print quality.
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Heat generation control
Using low-cost DC motors, this product grasps the variations of the torque
constants, coil resistances and power supply voltages of the individual DC motors
adequately to carry out heat generation control according to individual differences.
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CR variation measurement sequence
The variations of the torque constant, coil resistance and power supply voltage of
the motor are measured in a CR variation measurement sequence when the CR
mechanical load is in the initial status and saved into the EEPROM. According to
the variations (individual differences) measured in this sequence, the voltage is
corrected to make the drive current value constant (without an individual
difference).
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CR measurement sequence
To set the appropriate drive current value according to the variation of the CR
mechanical load, the mechanical load is measured in a CR measurement sequence
and saved into the EEPROM in a power-on or I/C change sequence. A fatal error
will occur if too much load is applied to the CR drive system.
The above control and sequences correct the drive current value of the CR Motor
according to not only the mechanical load but also the variations of the motor and like.
In addition, the resultant CR drive current value is used to calculate a heating value,
and when the specified heating value is reached, wait time is provided per CR path for
printing.
Figure 2-5. Carriage Mechanism
Table 2-1. Carriage Motor specification
Items Specifications
Type DC motor with brushes
Drive Voltage 42V (DC) ± 5% (voltage applied to driver)
Armature resistance 29.1
Ω
± 10% (per phase at 25 degrees)
Inductance 20.1mH ± 25%
Drive Method PWM, constant-current chopping
Driver IC A6627
Carriage Unit
CR Motor
Carriage Guide Shaft Timing Belt
CR Scale CR Encoder Sensor PW Sensor