Epson 2200 Service Manual - Page 41

EPSON Stylus PHOTO 2100/2200 Revision B 2.2.1 Carriage Mechanism The Carriage mechanism consists of the Carriage motor (CR motor), Carriage guide shafts A (main shaft), B (sub shaft), Platen gap adjustment mechanism, Carriage lock mechanism, and others. 2.2.1.1 Carriage Motor (CR Motor) Like the one of the conventional Stylus PHOTO 2000P, the Carriage mechanism of this product uses a DC motor as a drive source. The following indicates the Carriage driving DC motor specifications. Table 2-2. CR Motor Specifications Item Type Drive voltage Winding resistance Inductance Drive method Drive IC Specifications DC motor with brushes +42V +/- 5%(voltage applied to driver) 23.0Ω +/- 15% 24.0mH +/- 25% PWM, constant-current chopping A3958 The CR motor of the conventional model uses a stepping motor, and the carriage unit position was controlled by open loop control. To stabilize the printing quality and ensure silent operation, however, this product adopts the DC motor and linear encoderbased closed loop control like the Stylus PHOTO 2000P to control the Carriage speed and position. Also, the conventional DAC control was changed to PWM control. Simultaneously, the basic signal (PTS signal) is generated to time ink discharge. Driven by the CR motor, the Carriage unit moves within the printing area along the Carriage guide shaft of the printer mechanism during printing. PG change spring lever Release lever Release connect lever Linear encoder Intermittent Gear 24, 30 Photo coupler CR motor Carriage unit CR guide shaft A Figure 2-2. Carriage Mechanism CR guide shaft B Using low-cost DC motors, this product grasps the variations of the torque constants, coil resistances and power supply board output voltages of the individual DC motors adequately to carry out heat generation control according to individual differences. The variations of the torque constant, coil resistance and power supply board output voltage of the motor are measured in a CR variation measurement sequence when the CR mechanical load is in the initial status (Max. 150g.cm) and saved into the EEPROM (AC). 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) according to the variations (individual differences) measured in this sequence. Further, 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 6C, 6D in a power-on or IC change sequence. However, if 14 is saved at the EEPROM 6C and 05 at 6D, Fatal error will occur since too large load is applied to the CR drive system. Accordingly, not only the mechanical load but also the variations of the motor and like are taken into consideration to correct the drive current value of the CR motor. In addition, a heating value is calculated from the CR drive current value, and when the specified heating value is reached, wait time (0.3s to 7.9s) is provided per CR path for printing. OPERATING PRINCIPLES Printer Mechanism 41