Ribbon Shift Mechanism - Epson LQ-300 Service Manual

Operating Principles

2.1.5 Ribbon Shift Mechanism

This printer can be equipped with a color upgrade kit to print in color. The printer performs color
printing unidirectionally. The option is composed of the color ribbon shift mechanism. The color
ribbon feed mechanism is shared in common with black ribbon feed mechanism, and the shift
mechanism shifts the ribbon cartridge up and down.
Table 2-2 shows the CS motor specifications. The motor control system is open-loop, so that when
the color is being changed, the positioning is controlled by stepping pulse.
Category
Type
Drive Voltage
Coil Resistance
Drive Pulse Freauencv
Excitation Method
The ribbon shift mechanism consists of the color ribbon and color upgrade kit. The color upgrade
kit is composed of the CS motor, ribbon
The 1-inch-wide color ribbon is separated into four equal-width bands of different colors. The
ribbon shift mechanism shifts the ribbon cartridge up and down.
When the color ribbon cartridge is loaded, it is possible to print in up to seven colors. One of the
four colors on the ribbon is selected by the color ribbon cartxidge motion, which inserts
the plastic posts into the slots in the printer mechanism as a fulcrum. Figure 2-9 illustrates the color
shift mechanism. The mechanism
liner motion (up and down) of the color ribbon cartridge, using color shift cam gear.
Any color band can be selected by rotation of the CS motor, using the color home position (the
position of the black color band) as a starting point and reference position. Home position is
recognized by the CS motor stepping pulse. When printer is powered on, the CS motor is first
motor returns one step (yellow+ black), and the motor is stopped. Finally, the motor returns 223
steps (yellow+ black) and stops. This position is home position.
Table 2-5 gives coloring sequences. For halftones, as shown in the table, a color is created by
printing one color on top of another.
I
I
Note: The printer prints the brighter wlor first to prevent the ribbon from being stained,
2-8
Table 2-4. CS Motor Specifications
4-phase, 48-pole, PM-type stepping motor
35 VDC + 10%
150 Q * 5% (per phase, at 25° C or 77° F)
Color shift 500
gear/cam, motor driver IC, and color ribbon sensor.
shift
ribbon cartridge by converting the gear rotation to
Table 2-5. Coloring Sequences
Print Color
First Printing
Black Black
Magenta
Magenta
Cyan Cyan
Yellow
Yellow
Green Yellow
Orange Yellow
I
Violet
Requirement
DDS
Print Ribbon
Second Printing
—
—
—
l –
Cyan
Magenta
Cvan
I
1
portion of
a
l
I
. . . . .