EPSON Stylus Color 400 Service Manual 2
Chapter 2
Operating Principles
2.1 OVERVIEW...............................................................................................................1
2.1.1 Printer Mechanism .................................................................................................................... 1
2.1.1.1 Printing Mechanism...................................................................................................... 2
2.1.1.1.1 Printing Process................................................................................................3
2.1.1.1.2 Printing Method.................................................................................................4
2.1.1.2 Carriage Mechanism .................................................................................................... 7
2.1.1.2.1 Paper Gap Adjust Mechanism ........................................................................ 10
2.1.1.3 Paper Feed Mechanism and Pump Mechanism.........................................................11
2.1.1.4 Ink System.................................................................................................................. 14
2.1.1.4.1 Pump Mechanism ........................................................................................... 15
2.1.1.4.2 Cap Mechanism.............................................................................................. 17
2.2 Electrical Circuit Operating Principles................................................................18
2.2.1 C206 PSB/PSE Power Supply Board ..................................................................................... 19
2.2.2 C206 MAIN Board..................................................................................................................... 21
2.2.2.1 Reset Circuits............................................................................................................. 23
2.2.2.2 Sensor Circuits........................................................................................................... 24
2.2.2.3 EEPROM Control Circuits .......................................................................................... 25
2.2.2.4 Timer Circuit............................................................................................................... 26
2.2.2.5 DRAM Control ............................................................................................................ 26
2.2.2.6 Print Head Control Circuit........................................................................................... 27
2.2.2.7 PF (Pump) Motor Drive Circuit ................................................................................... 30
2.2.2.8 CR Motor Drive Circuit ............................................................................................... 31
Chapter2 Operating Principles
2.1 OVERVIEW
This section describes Printer Mechanism, electric circuit board (C206 PSB/PSE, C206 Main, C206PNL
board) of Stylus Color 400.
2.1.1 Printer Mechanism
Unlike previous EPSON Ink Jet printers, printer mechanism of Stylus Color 400 does not have exclusive
mechanism to change over paper feeding and Pumping operation. In stead, this control is done by the
turning direction of paper feed/pump motor and position of carriage at that time. Also, unlike previous print
heads, print head of this printer became one unit combined with black and CMY head. Black head has
64 nozzles, 180 dpi(vertical direction) and CMY head has 21 nozzles, 90 dpi (vertical direction). Also,
since these print head is driven by frequency 14.4Khz, this printer can print double resolution(1440
dpi/100-dpi) than Stylus Color. Following figure2-1 shows outline of printer mechanism.
Carriage Unit
(Prinr Head Unit)
Platen Drive Mechanism
Paper Pickup Mechanism
Pump Drive Mechanism
Timing Belt
Paper Pick Up
Trigger Lever
Pumping Position
Paper Feed Motor
Rev.A
Carriage Motor
Figure 2-1. Stylus Color 400 Printer Mechanism Block Diagram
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EPSON Stylus Color 400 Service Manual
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As major printer mechanisms in the figure 2-1, there are four major mechanisms as they are listed below.
1) Printing mechanism 2) Carriage unit 3) Paper pick up mechanism4) Pump drive mechanism
2.1.1.1 Printing Mechanism
Basic principles of the print head which plays major role of printing mechanism is the same as previous
models; on demand type MACH head method, but there is some difference in the resolution. (Refer to
figure1-1) Also, unlike Stylus Color IIs, 820, 200 automatic correction type, in order to fix the dispersion of
mufti layer piezo electric element which is used for driving each nozzles, it is necessary to input the VH
value written on the side of print head by using exclusive program when you replace print head, control
board, or the printer mechanism.(However, there are no resistor array to decide the VH voltage on the
main control board.) Following explains print head.
PZT
PZT is an abbreviation of Piezo Electric Element. Print signal from C206 board is sent through the
driver board on the print head unit and to the PZT . Then, the PZT pushes the top cavity which has
ink stored, and make the ink discharge from each nozzle located on the nozzle plate.
Cavity Set
Ink which is absorbed from ink cartridge go through the filter and will be stored temporarily in this
tank, which is called “cavity” until PZT is driven.
Nozzle Plate
The board with nozzle holes on the printer head surface is called Nozzle Plate.
Filter
When the ink cartridge is installed, if any dirt or dust around the cartridge needles are
absorbed into the head inside, there is a great possibility of causing nozzle clog and
disturbance of ink flow and finally causing alignment failure and dot-missing. In order to
prevent this, filter is set at cartridge needle below and ink is once filtered here.
Printhead driver board
Ink Cartridge Sensor
Actuator
Cartridge needle
(Ink Cartridge)
PZT
Ink Supply Tube
Cavity set
Nozzle Plate
Figure 2-2. Print Head Sectional Drawing
2-
Filter
Rev.A
Chapter2 Operating Principles
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2.1.1.1.1 Printing Process
Following figures indicate the sectional drawing of normal state and ejecting state of the print head.
(1) Normal State:
When the print signal is not output, PTZ also does not move in the waiting state(normal state).
PZT
Cavity
Ink Course
Nozzle
Figure 2-3. Print Head Normal State
(2) Ejecting State:
When the print signal is output from the C206 main board, IC(IR2C72C:Nozzle Selector) located
on the Print head unit latches the data once by 1-byte unit. Appropriate PZT latched by nozzle
selector is pushed into the cavity by applying common voltage from the C206 main board.
By this operation, ink that is stored in the cavity pops out from nozzles.
Nozzle Plate
Figure 2-4. Print Head Ejecting State
Rev.A
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EPSON Stylus Color 400 Service Manual
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2.1.1.1.2 Printing Method
This section explains printing method of actual printing such as printing text at various resolution
select/printing mode and graphics printing. In order to prevent white or color banding which are peculiar
problem of ink-jet, new Micro-Weave functions are added to the previous Micro-Weave function.
The number of nozzles and printing mode according to the selected resolution are used separately by a
user. The table below shows relation between selected resolution and printing mode.
1) Full Overlap Micro-Weave
2) Part Line Overlap Micro-Weave
3) Micro-Weave: (same as previous control)
Table 2-1. Resolution and Printing mode
Vertical
direction
[dpi]
Printing
mode
Paper feed
pitch
[inch]
Forward
Overlap-
Nozzle
Non
Overlap-
Nozzle
Backward
Overlap-
Nozzle
Not used
Nozzle
360 FOL M/W 15/360
M/W 31/360 ---
720 FOL M/W 15/720
POL M/W 29/720
Note1:
M/W means Micro-Weave.
Note2:
Note3: POL means Part line Overlap Micro- Weave.
Note4:
Following explains operation outlines of new Micro-Weave functions listed above.
[1. Full Overlap Micro-Weave]
In order to print one line at horizontal direction, this printing method is designed to complete a printing
pattern by two-pass carriage operation with two different types of dot. When this two different types of dot
pass one same line twice, it does not print the same dot twice.
FOL means Full Overlap Micro-Weave.
Forward Overlap-Nozzle and backward Overlap -Nozzle are described in the [1.Full Overlap
Mirco-Weave] and [2.Part line Overlap Micro-Weave] below.
The nozzles whose configuration completely match to the black and CMY nozzle are used.
(Usually Micro-Weave type)
Therefore, all nozzles in case of CMY nozzle and #1∼#63 nozzles in the B2 line in case of
black head are its objects. (B1 line is not used at Micro-Weave. Refer to figure1-1 for detail of
nozzle configuration.)
Out of these 4 color nozzle objects, the number of all nozzles which are going to be used are
divided equally into 2 groups.
Paper feeding will be done as many as each number of nozzles which are divided into two
groups and the same number of dots.(for example, if there are two 10-nozzle groups during
360-dpi printing at longitudinal direction, paper feeding of 10/360-inch becomes available.)
At this time, two groups perform Micro-Weave individually and particular lines are passed by
two different nozzles.
#16∼#30
#16∼#30
#30∼#32 #4∼#29 #1∼#3
---
#1∼#31
---
#1∼#15 #31∼#32
--- #32
#1∼#15 #31∼#32
---
Note1)
2-
These nozzles which are divided into two groups must be set and divided in order to
be a pair of odd and even number.
Rev.A
Chapter2 Operating Principles
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Note2)
Two groups which are divided according to each elements will be divided either even dot or
odd dot when particular lines(level direction line) are formed and eventually, these lines will be
completed at selected resolution. Following is a conceptual figure when full overlap microweave orms a particular line.
Nozzle No.#9
Condition: 360-dpi printing
Nozzle: Total 10 nozzle/each color
Nozzle No.#4
Particular line(Completed line)
Figure 2-5. Full Overlap Micro-Weave
Note 3)
If the line which is about to be printed is even line:
If the line which is about to be printed is odd line:
[2.Part Line Overlap Micro-Weave]
This printing method is to perform Micro-Weave printing, overlapping a part of nozzles which are
used for printing. As a result, a part of raster which is overlapped consists of different browse with
different nozzles. The figure below shows 1-line Overlap at 5-dot sending as an example with
explanation on the next page.
The way firmware decides which nozzle becomes even dot or odd dot is determined
as it is described below.
First dot prints odd dot lines and 2nd dot prints even dot lines.
1st dot prints even dot lines and 2nd dot prints odd dot lines. Eventually, horizontal resolution
will be the same resolution as selected one.
360-dpi
Pass1
#1
#2
#3
#4
#5
#6
2
Note1: The paper feed pitch is 5/360-dpi in this figure.
Note2: Mark of and mean overlap nozzle.
3
4
5
6
Raster 1
Raster 10
7
8
9
10
11
Figure 2-6. Part line Overlap Micro-Weave
Rev.A
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EPSON Stylus Color 400 Service Manual
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The difference between Full-Overlap Micro-Weave and Part line Overlap Micro-Weave are following;
Full-Overlap Micro-Weave:
Printing is performed, judging if nozzles are even or odd dot by 2 different dots with all
different rasters.
Part line Overlap Micro-Weave:
After particular nozzles(only#1, and #6 in the figure2-7) are determined as overlap nozzles,
even or odd dot will be determined like Full-overlap Micro-Weave does.
(Forward Overlap Nozzle is determined as even and backward nozzle is odd.)
Also, nozzles other than particular nozzles can print at even and odd dot just by one
nozzle.
1) Overlap Nozzle : Head drive frequency is driven half of the ordinal one like 2)
below.
2) Nozzle other than Overlap nozzle : Head drive frequency is twice as much as overlap nozzle.
Usually, the firmware changes over automatically these full overlap Micro-Weave, Part line Overlap
Micro-Weave, and ordinal Micro-weave according to the selection of resolution. Also, when these three
printing modes are performed by the Stylus Color 400, the printer performs top and bottom margin
process in order to control the overprinting volume as little as possible.
2-
Rev.A
Chapter2 Operating Principles
7
2.1.1.2 Carriage Mechanism
Carriage mechanism is to drive the carriage with print head mounted from left to right or vice versa.
The carriage drive motor in this printer is a 4-phase, 200-pole, stepping motor and is driven by
1-2phase, 2-2phase and W1-2phase drive method. This stepping motor allows the carriage to
move freely to the particular positions which is necessary for various operation, such as paper feeding,
ink absorbing, flashing, ink exchange and cleaning operations. The tables below shows carriage motor
specifications and motor controls at each mode.
Table 2-2. Carriage Motor Specification
Item Description
Motor type 4-phase/200-pole Stepping motor
Drive voltage Range
Internal coi l resistance
Driving speed(frequency) range[csp(pps)]
Control method Bi-Pola Drive
Table 2-3. Motor Control at Each Mode
Mode Driving speed
[CSP]
High speed skip 340 4080 W1-2, 2-2,1-2phase drive*
Printing(Normal) 200 2400 W1-2phase drive
Printing(SLQ) 100 1200 W1-2phase drive
Capping 80 960 W1-2phase drive
Wiping 40 480 W1-2phase drive
Cap(valve release) 20 240 W1-2phase drive
Withdrawal of cap 5 60 W1-2phase drive
42VDC ± 5%
7.8 Ohms ± 10%(per phase under 25 °C
environment)
5(60)∼340(4080)
Drive frequency
[PPS]
Drive method
*Note 1):
Acceleration 1 mode → Acceleration 2 mode → Deceleration 1 mode → Deceleration 2 mode
The reason why plural drive methods exist is that following some sequences described below
exist in the each mode and stable carriage operation and printing are performed individually
by different drive methods. This drive method is especially necessary for high speed skip.
A
/A
C206 MAIN Board
Rotor
Connecter CN6
B
/B
Figure 2-7. CR(PF) Motor Internal Block Diagram
Rev.A
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EPSON Stylus Color 400 Service Manual
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The table below shows W1-2 phase drive sequence at each steps when the rotor of carriage motor
makes one rotation. In the Stylus Color 400, in addition to a function that printing is performed with W1-2
drive phase, high speed skip mode which is a function to skip over the blank from the end of the printing
data to the next data starting point with high seed can be also performed by 2-2 and 1-2 phase drive.
W1-2 phase requires 4 times as much steps as 2-2 phase drive, calculating 2-2 phase as standard.
By using this method, it becomes possible to supply constant stable torque to the motor. As a result, it
also became difficult to be influenced by vibration from the printer mechanism during printing.
Table 2-4. Motor Drive Sequence(W1-2 phase drive)
Sequence
Number
Phase a 10a l1a Current
0010+2/3010+2/3
1001+1/3000+1
2X110000+1
3101-1/3000+1
4110-2/3010+2/3
5100-1X01+1/3
6100-11110
7100-1101-1/3
8110-2/3110-2/3
9101-1/3100-1
10X110100-1
11001+1/3100-1
12010+2/3110-2/3
13000+1101-1/3
14000+1X110
15000+1001+2/3
Phase A Phase B
Phase b 10b l1b Current
Duty
Duty
This W1-2 phase drive (or 2W1-2 phase drive) is called Micro-step and is attached with so called
2/3 • Vref or 1/3 • Vref factor, compared with drive current value (Vref100%) which is supplied at 2-2phase
drive. This Micro-Step allows the rotor to have delicate rotation. In the 2-2 phase drive method, it is usually
required to take 4-step sequence in order to rotate the rotor once. However, in case of W1-2 phase, it is
required to take 16-step sequence(in the table 2-4, sequence 0∼15) which is 4 times more than 2-2 phase
method to do that. Also, in case of 2W1-2 phase drive which can be seen in the Stylus Color etc., it takes
2-step to rotate the rotor once. The table below shows relation of rotation direction of rotor and carriage
proceeding direction.
Table 2-5. Relationship Between Rotor Direction and Carriage Operation
Carriage proceeding
direction
HP→80 column direction
80 column→HP direction
Rotation direction of
Rotor
Looking from rotor output
side, clockwise direction
Looking from rotor output
side, counterclockwise
direction
Drive method Proceeding order of
sequence
2-2, 1-2, W1-2 phase
2-2, 1-2, W1-2 phase
Sequence No.0→15
Sequence No.15→0
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Rev.A
Chapter2 Operating Principles
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The figure below shows the carriage mechanism. The print head as a core of the printing mechanism is
stored in the carriage unit. This print head keeps the tilt of print head in flexible and adjustable structure by
moving the adjustment lever up and down by the tilt adjustment mechanism. (Refer to chapter 4 for more
details) Also, parallelism adjustment lever is mounted on the left and right side of carriage guide shaft and
it adjusts parallelism degree between platen and shaft when this shaft is installed to the printer
mechanism.
After this adjustment is completed and operate PG adjustment lever, it becomes possible to change the
space between the platen surface and the print head surface into 2 phases; either 1.1mm to 1.8mm. It is
possible to vary the space between platen surface and print head by rotating the axis of carriage guide
shaft which itself is decentralized, with the operation of PG lever. This is the mechanism that user can
adjust the appropriate PG value by himself according to the paper thickness or any other environmental
conditions such as paper curl.
Carriage lock mechanism is to prevent the carriage from being left at uncap position for a long time
because of vibration during the printer transport or mishandling by the users. If the carriage is left at uncap
position and uncap state of the print head for long time, an ink on the print head surface gradually
becomes viscosity. As a result, the nozzle will be unable to discharge an ink. To make matters worse, the
holes(crater) of nozzle may be completely clogged by the viscosity ink and it may not be able to return to
the normal condition just by cleaning operation. In order to prevent this, printer goes to carriage lock state
at the following conditions.
After Power OFF operation:
If the power is turned off on the way of printing or any other performance, carriage lock will be
performed in the end after completing initialize operation.
After power ON operation:
After power is turned on and automatic P-On Cleaning is performed, then carriage lock will be
performed. P-On Cleaning is an automatic head cleaning that is performed when the power is
turned on. The timer IC always calculates printer’s power OFF time by the power of lithium battery
mounted on the C206 main board. P-on cleaning function automatically selects the cleaning level
according to the time which the printer is not in used.
After Eject the paper:
After Load/Eject button is pressed and the paper is ejected, if the data is not input, the printer
performs carriage lock and goes to standby state. However, if the paper is loaded to the printer
inside by Load/Eject button, the printer does not perform carriage lock operation.
Paper Feed Motor
Eject Roller
Paper guide(Front)
Carriage home position Sensor
PF Roller
Timing Belt
Carriage Unit
Front Side
Figure 2-8. Carriage Mechanism Top (Viewing)
Carriage Motor
Rear Side
Parallelism
Adjust Lever
Fixing Bush
Carriage
Guide Shaft
Rev.A
2-
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