Operating Principles

2.1 Overview

This section describes the operating principles of the printer mechanism and electrical circuit boards. The Stylus COLOR 580 has only the following two circuit boards and dose not have control panel:

□ Power supply board:C367 PSB/PSE

NOTE: *1): C379MAIN-B board is used for the product in the first mass production and it will be changed to C3 79MAIN-C board at an early date. The major difference is that C379MAIN-C has one chip CPU which include the ASCI function. This section describes the operation principle of C379MAIN-C.

2.1.1 Printer Mechanism

The printer mechanism for Stylus C0L0R 580 is designed newly. But, the basic component of the printer mechanism is same as previous product. This printer consists of Print Head, Carriage Mechanism, Paper Feeding Mechanism, Paper Loading Mechanism, Ink System (Pump Mechanism, Cap Mechanism, and Carriage Lock Mechanism).

Like other EPS0N ink jet printers, the Stylus C0L0R 580 is equipped with two stepping motors; one for ASF, Paper feeding/ Pump mechanism, and one for CR mechanism. ASF unit uses rear entry front eject system. This ASF unit is also designed newly and single LD roller loads the paper to the printer mechanism.

For cap assembly, Stylus C0L0R 580 uses valveless mechanism; new design for this model.

Printhead Circuit Driver
Figure 2-1. Printer Mechanism block diagram

2.1.2 Printhead

The print head uses a new developed U-CHIPS head and Stylus COLOR 580 can perform multiple shot printing and variable printing. Printheads nozzle configuration is as follows.

■ 48 nozzles x 1 row: Black (nozzle pitch of the row: 1/120 inch)

■ 45 nozzles x 1 row: Color (nozzle pitch of the row: 1/120 inch)

In the one row for the color, 15 nozzles are assigned for each yellow, magenta, cyan color)

The basic operating principles of the printhead, which plays a major role in printing, are the same as previous models; on-demand method which uses PZT (Piezo Electric Element). In order to uniform the amount of ejecting ink, the printhead has its own head ID (6 digits for this printhead) which adjust PZT voltage drive features. The printhead stores the head ID to EEPROM and generates appropriate PZT drive voltage to prevent amount of ink from varying by printheads.

Following explains printhead basic components.

PZT is an abbreviation of Piezo Electric Element. Certain amount of voltage expands and contracts PTZ. The drive wave generated on MAIN board drives PZT and PZT pushes the top cavity which has ink stored to discharge the ink from each nozzle on the nozzle plate.

The ink absorbed from the ink cartridge goes through the filter and then is stored temporarily in this tank called "cavity" until PZT is driven.

The board with nozzle holes on the printhead surface is called Nozzle Plate.

When the ink cartridge is installed, if any dirt or dust around the cartridge needle is absorbed into the head, there is a great possibility of causing nozzle clog and disturbance of ink flow, and finally causing alignment failure and dot missing. To prevent this problem, a filter is set below the cartridge needle, where ink is filtered.

Epson Inkjet Head Circuit
Figure 2-2. Printhead Sectional Drawing

2.1.2.1 Printing Process

This section explains the process in which the printheads of On-Demand inkjet printers eject ink from each nozzle.

1. Normal State:

When no printing signal is sent from PC, or no PZT drive voltage is applied, PZT does not change shape, therefore PZT does not squeeze the cavity. Ink pressure inside the cavity is kept normal. (Refer to Figure 2-3.)

2) Ejecting State:

When the print signal is output from the C379MAIN-C board, IC (Nozzle Selector) located on the printheads unit latches data once by 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. By this operation, ink stored in the cavity spurts out from nozzles.(Refer to Figure 2.1.2.2.)

□ Multiple shot printing

This printing mode is developed to improve the print quality on plain paper or transparencies in low resolution. The multiple shot printing mode uses normal dot and the number of dot shots varies from 1 shot to maximum 4 shots depending on the print data to enable sharp image output even in a low resolution.

□ Variable dot printing

This printing mode is developed to improve the print quality on exclusive paper. This mode is basically the same as variable dot printing mode used on other products /; micro dot, middle dot, and large dot compose this mode. Print dot size varies according to print data and this mode enables even sharper image output on exclusive paper.

PZT drive voltage

PZT drive voltage

Figure 2-3. Printhead printing process 2.1.2.2 Printing Method

For print dot system, Stylus COLOR 580 has the following two kinds of printing modes.

■ Multiple shot printing

■ Variable dot printing

The above two printing modes are automatically selected depending on the media and the resolution setting of the printer driver. The following explains each printing mode.

2.1.3 Carriage Mechanism

The carriage mechanism consists of Carriage motor (CR motor), Carriage unit (including printhead), CR timing belt, CR guide shaft, CR guide frame, CR home & I/C detector (HP/PE/IC sensor) etc. The carriage mechanism moves the carriage back and forth according to the drive from the carriage motor. The following stepping motor is mounted to drive CR mechanism. (See the table below.)

Table 2-1. Carriage Motor Specification

Items

Specifications

Type

4-Phase/ 48-Pole PM Stepping motor

Drive Voltage

+42 V +/ - 5% (DRV IC voltage)

Coil Resistance

10.8 Q +/ - 10% (per phase at 25 degree)

Inductance

15 mH +/ - 20%(1KH 1 VmA)

Drive Method

Bi-Polar drive

Driver IC

+2 0

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