Epson Stylus Scan 2000, Service Manual

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EPSON Stylus Scan 2000 Revision A
Operating Principles Electrical Circuit Operating Principles 56
2.5.2.5 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.
2.5.2.6 Printhead Control Circuit
The printhead control circuit of EPSON Stylus Scan 2000 has following
characteristics.
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Common wave form circuit became one HIC.
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Slight vibration mode is added.(when the CR motor is accelerating)
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High speed drive 14.4Khz (trapezoidal wave form
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Big Nozzle configuration (resolution in the vertical direction) 90dpi
(However, black nozzle is 2 lines structure)
Also, EPSON Stylus Scan 2000 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 following are required conditions to perform the normal-
dot 2-dot.
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At the OHP, Normal sheet setting (360 X 360 dpi)
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At the ordinary paper and resolution 360 X 360 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.