Printhead Operation; Carriage Mechanism - Epson Stylus Photo 870 Service Manual

EPSON Stylus Photo 870/1270
! PZTs (piezoelectric elements) and nozzle plate
Print signals from the C304MAIN board are sent through the driver
board (nozzle selector) on the printhead unit to each PZT. The PZTs
then push against the top of the ink cavity to discharge the ink
from each nozzle on the nozzle plate.
To correct for manufacturing variations in the printhead's PZTs, you
must use the adjustment program to input the printhead ID (written on
top of the printhead) whenever you replace the printhead or main
board.

2.2.2 Printhead Operation

Figure 2-2 and Figure 2-3 on the next page show the normal and
ejecting states of the printhead.
! Normal state
When no print signal is output, PTZ remains in a waiting (normal)
state, as shown in Figure 2-2.
! Ejecting state
When the print signal is output from the C304MAIN board, the IC
located on the printhead unit (IR4C463S: Nozzle Selector) latches
data once per
1-byte unit. An appropriate PZT latched by the nozzle selector is
pushed into the cavity by the common voltage applied from the
main board. Ink stored in the cavity then spurts out from nozzles,
as shown in Figure 2-3.
Ink path PZT
Nozzle
Figure 2-2. Printhead in Normal State
Figure 2-3. Printhead in Ejecting State

2.3 Carriage Mechanism

The carriage mechanism for the EPSON Stylus Photo 870/1270 is
similar to other ink jet printers, except it is driven by a DC motor. The
table below lists the carriage motor specifications.
Table 2-2. Carriage Motor Specifications
Specification
Type Brush-type DC motor
Drive voltage +42 V +/- 5% (DRV IC voltage)
Internal resistance 29.2 ohms +/- 25%
Chapter 2 Technical Overview
Cavity
Nozzle plate
Description
7