Epson 440 User Manual download pdf (Page 72)

EPSON Stylus Color 440/640/740 Revision A

Chapter 2 Operating Principles 72

2.2.4.5 DRAM Control

In the Dynamic RAM control, output and formation of CAS and RAS

control signals become necessary in addition to the output of CS signal.

The CPU not only controls that but also perform the output of CS signal

of P-ROM. Refresh timing is performed in the CAS Before RAS.

2.2.4.6 Print Head Control Circuit

The print head control circuit of Stylus Color 440/640/740 has following

characteristics.

Common wave form circuit became one HIC.

Slight vibration mode is added.(when the CR motor is

accelerating)

High speed drive 14.4Khz (trapezoidal wave form

Big Nozzle configuration (resolution in the vertical

direction)90dpi

(However, black nozzle is 2 lines structure)

Also, Stylus Color 440/640/740 does not have Micro-dot control as dot

shooting control, but there are two types; Normal-dot and Normal dot-

2dot.Normal-dot-2dot was called Dual Firing in the Stylus Color IIs/820.

These setting/change are controlled automatically by setting of the

printer driver that is determined by the user. The followings are required

conditions to perform the normal-dot 2-dot.

At the OHP, Normal sheet setting (360X360 dpi)

At the ordinary paper and resolution 360X360 dpi setting

The control circuit is considered as 2 divided parts; 1) trapezoidal wave

form generation circuit (common drive circuit) to drive PZT in the head,

and 2) Nozzle-selector drive circuit to determine which nozzle should be

used. The Nozzle-Selector is attached to the head unit just like the

previous models. The common drive circuit is hybridized as one HIC

and mounted on the main control board.

See the following pages for the head drive circuit block diagrams for

each printer.

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Epson 440 User Manual Page 72